JP7718195B2 - Fastening tool - Google Patents

Description

The present invention relates to a fastening tool in which a driver bit is engaged with a screw, the driver bit is used to press the screw against an object to be fastened, and the driver bit is rotated to screw in the screw.

A portable tool known as a driving machine uses the air pressure of compressed air supplied by an air compressor or the combustion pressure of gas to drive connecting fasteners loaded in a magazine one after another from the tip of a driver guide.

A tool that rotates a bit to tighten a screw and moves the bit in the direction of tightening the screw has previously been proposed: a pneumatic screw driver that uses an air motor to rotate the bit and air pressure to move it in the direction of tightening the screw (see, for example, Patent Document 1).

A screw driver has also been proposed in which a spring is compressed by the driving force of a motor that rotates the screw, and the screw is driven in by the bias of the spring (see, for example, Patent Document 2).

Patent No. 5262461 Patent No. 6197547

With both air-powered screw drivers and spring-loaded screw drivers, the driver bit can move toward the object being fastened even when there is no screw, potentially causing the driver bit to collide with the object.

The present invention was developed to solve these problems, and aims to provide a fastening tool that can control the movement of the driver bit in a direction approaching the object to be fastened based on the presence or absence of a screw.

In order to solve the above-mentioned problems, the present invention is a fastening tool comprising a bit holding portion that detachably holds a driver bit and is rotatable in the circumferential direction of the driver bit and movable in the axial direction, a motor that rotates the bit holding portion and moves the bit holding portion along the axial direction, and a control portion that controls the axial position of the bit holding portion with the amount of rotation of the motor, wherein the control portion limits the output of the motor when it detects a load on the motor that is rotated in one direction to move the bit holding portion toward the object to be fastened, and stops the rotation of the motor when it determines that there is no screw based on the load on the motor.

In this invention, when it is determined that there are no screws based on the load on the motor, the motor stops rotating and the forward movement of the driver bit attached to the bit holder is restricted.

This invention allows the driver bit to be controlled to move closer to the object to be fastened based on whether or not a screw is present.

FIG. 2 is a side cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. FIG. 2 is a top cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. FIG. 2 is a front cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. FIG. 2 is an exploded perspective view showing an example of the internal structure of the fastening tool of the present embodiment. 1 is a perspective view showing an example of a fastening tool according to an embodiment of the present invention; 1 is a perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; 1 is a perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; 1 is a cross-sectional perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; 1 is a cross-sectional perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; 1 is a cross-sectional perspective view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention; 1 is a top cross-sectional view showing an example of a configuration of a main part of a fastening tool according to an embodiment of the present invention. FIG. 2 is a top cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. FIG. 2 is a top cross-sectional view showing an example of the internal structure of the fastening tool of the present embodiment. FIG. 10 is a cross-sectional view showing an example of a detachable holding mechanism. FIG. 10 is a cross-sectional view showing an example of a detachable holding mechanism. FIG. 10 is a perspective view showing an example of a detachable holding mechanism. FIG. 10 is a perspective view showing an example of a detachable holding mechanism. FIG. 2 is a perspective view showing an example of a screw feed portion and a nose portion of the present embodiment. FIG. 2 is a perspective view showing an example of the fastening tool of the present embodiment, as viewed from the rear. FIG. 2 is a perspective view showing an example of the fastening tool of the present embodiment, as viewed from the rear. FIG. 2 is a perspective view showing an example of the fastening tool of the present embodiment, as viewed from the rear. FIG. 2 is a perspective view illustrating an example of a setting unit. 1 is a block diagram showing an example of a fastening tool according to an embodiment of the present invention; 10A and 10B are side cross-sectional views showing an example of the operation of the fastening tool of the present embodiment. 10A and 10B are cross-sectional top views showing an example of the operation of the fastening tool of the present embodiment. 4 is a flowchart showing an example of an operation of the fastening tool according to the present embodiment. FIG. 4 is a cross-sectional view showing a fastened state of the screw. FIG. 4 is a cross-sectional view showing a fastened state of the screw. FIG. 4 is a cross-sectional view showing a fastened state of the screw. 10A and 10B are explanatory views showing an example of an operation for setting standby positions of a holding member and a moving member in a first initialization operation. 10A and 10B are explanatory views showing an example of an operation for setting standby positions of a holding member and a moving member in a first initialization operation. 10A and 10B are explanatory views showing an example of an operation for setting standby positions of a holding member and a moving member in a first initialization operation. 10A and 10B are explanatory views showing an example of an operation for setting standby positions of a holding member and a moving member in a first initialization operation. 10A and 10B are explanatory views showing an example of an operation of moving a holding member and a moving member to a standby position in a second initialization operation. 10A and 10B are explanatory views showing an example of an operation of moving a holding member and a moving member to a standby position in a second initialization operation. 10A and 10B are explanatory views showing an example of an operation of moving a holding member and a moving member to a standby position in a second initialization operation. 10 is a flowchart showing an example of an operation for selecting a first initialization operation and a second initialization operation. 10 is a flowchart showing a modified example of the operation of the fastening tool of the present embodiment. 10 is a graph showing the relationship between the output of the contact switch unit and the control of the bit rotating motor and the bit moving motor. 10 is a flowchart showing another modified example of the operation of the fastening tool of the present embodiment. 10 is a graph showing the relationship between the load and the control of the bit rotation motor. 10 is a graph showing the relationship between the load and the control of the bit rotation motor. 10 is a flowchart showing another modified example of the operation of the fastening tool of the present embodiment. 10 is a graph showing the relationship between the rotation speed of a bit rotating motor and a bit moving motor under feedback control. 10 is a graph showing the relationship between the moving speed of a screw caused by the rotation of a bit rotating motor under feedback control and the moving speed of a driver bit caused by a bit moving motor. 10 is a flowchart showing another modified example of the operation of the fastening tool of the present embodiment. 10 is a graph showing the relationship between the load and the control of the bit moving motor. 10 is a graph showing the relationship between the load and the control of the bit moving motor. 10 is a flowchart showing another modified example of the operation of the fastening tool of the present embodiment.

The following describes an embodiment of the fastening tool of the present invention with reference to the drawings.

<Configuration example of fastening tool according to this embodiment>
Fig. 1A is a side cross-sectional view showing an example of the internal structure of the fastening tool of this embodiment, Fig. 1B is a top cross-sectional view showing an example of the internal structure of the fastening tool of this embodiment, Fig. 1C is a front cross-sectional view showing an example of the internal structure of the fastening tool of this embodiment, Fig. 2A is an exploded perspective view showing an example of the internal structure of the fastening tool of this embodiment, and Fig. 2B is an external perspective view showing an example of the fastening tool of this embodiment.

The fastening tool 1 of this embodiment includes a bit holding unit 3 that holds a driver bit 2 rotatably and axially movably, a first drive unit 4 that rotates the driver bit 2 held by the bit holding unit 3, and a second drive unit 5 that axially moves the driver bit 2 held by the bit holding unit 3.

The fastening tool 1 also includes a screw storage section 6 in which the screw 200 is stored, a screw feed section 7 that feeds the screw stored in the screw storage section 6, and a nose section 8 that is pressed against the object to be fastened and from which the screw 200 is ejected.

Furthermore, the fastening tool 1 includes a tool body 10 and a handle 11. The fastening tool 1 also includes a battery mounting portion 13 at the end of the handle 11, to which a battery 12 can be detachably attached.

The fastening tool 1 has a tool body 10 that extends in one direction along the axial direction of the driver bit 2, as indicated by arrows A1 and A2, and a handle 11 that extends in another direction that intersects with the extension direction of the tool body 10. The direction in which the tool body 10 extends, i.e., the axial direction of the driver bit 2, as indicated by arrows A1 and A2, is defined as the front-to-back direction of the fastening tool 1. The direction in which the handle 11 extends is defined as the up-to-down direction of the fastening tool 1. Furthermore, the direction perpendicular to the extension direction of the tool body 10 and the extension direction of the handle 11 is defined as the left-to-right direction of the fastening tool 1.

The first drive unit 4 is located at the rear, on one side of the tool body 10, across the handle 11. The second drive unit 5 is located at the front, on the other side of the tool body 10, across the handle 11.

The screw storage section 6 stores multiple screws 200 connected by connecting bands, forming a spirally wound connected screw.

Figures 3A and 3B are perspective views showing an example of the main configuration of a fastening tool according to this embodiment, Figures 4A to 4C are cross-sectional perspective views showing an example of the main configuration of a fastening tool according to this embodiment, and Figure 5 is a top cross-sectional view showing an example of the main configuration of a fastening tool according to this embodiment, showing details of the bit holding unit 3 and first drive unit 4. Next, the bit holding unit 3 and first drive unit 4 will be described with reference to each figure.

The bit holding unit 3 is an example of a tool holder, and includes a holding member 30 that detachably holds a driver bit 2, which is an example of a tool, a rotation guide member 31 that supports the holding member 30 so that it can move forward and backward along the axial direction of the driver bit 2, as indicated by arrows A1 and A2, and rotates together with the holding member 30, a moving member 32 that moves the holding member 30 forward and backward along the rotation guide member 31, and a biasing member 33 that biases the moving member 32 backward as indicated by arrow A2.

The holding member 30 is composed of, for example, a cylindrical member whose outer diameter is slightly smaller than the inner diameter of the rotary guide member 31 and which can be inserted inside the rotary guide member 31. The holding member 30 has an opening 30a at its front end along the axial direction of the driver bit 2, whose shape matches the cross-sectional shape of the driver bit 2. The holding member 30 is provided with a detachable holding mechanism 30c in the opening 30a that detachably holds the driver bit 2. The opening 30a of the holding member 30 is exposed to the inside of the rotary guide member 31, and the driver bit 2 is removably inserted into the opening 30a.

The rotary guide member 31 extends in the direction of extension of the tool body 10, i.e., in the front-to-rear direction indicated by arrows A1 and A2 along the axial direction of the driver bit 2. The rotary guide member 31 is cylindrical, with the retaining member 30 fitted inside, and its front end is rotatably supported via a bearing 34a, an example of a bearing, on a metal front frame 10b provided on the front side of a resin case 10a that forms the exterior of the tool body 10. The rear end of the rotary guide member 31 is connected to the first drive unit 4.

The rotation guide member 31 has grooves 31a formed on two radially opposing sides, extending in the front-to-rear direction indicated by arrows A1 and A2 along the axial direction of the driver bit 2. The rotation guide member 31 penetrates the holding member 30 radially, and connecting members 30b protruding from both sides of the holding member 30 fit into the grooves 31a, connecting the rotation guide member 31 to the holding member 30 via the connecting members 30b.

The holding member 30 has a hole that penetrates perpendicular to the rotational direction of the driver bit 2, and the connecting member 30b is inserted into this hole and fixed in place with a pin 30f. The connecting member 30b is a cylindrical member with an oval cross-section.

The longitudinal direction of the oval shape of the connecting member 30b is oriented along the extension direction of the groove 31a, which is parallel to the axial direction of the driver bit 2 as indicated by arrows A1 and A2, and the lateral direction of the oval shape is oriented perpendicular to the extension direction of the groove 31a as indicated by arrows B1 and B2, i.e., along the rotational direction of the rotation guide member 31. The width of the oval shape's lateral direction, i.e., the width along the rotational direction of the rotation guide member 31, of the connecting member 30b is slightly smaller than the width of the groove 31a along the same direction.

As a result, the connecting member 30b inserted into the groove 31a is supported in the groove 31a so as to be movable along the axial direction of the rotary guide member 31. Furthermore, movement of the connecting member 30b in the rotational direction relative to the rotary guide member 31 is restricted between one side surface or the other side surface of the groove 31a, which is aligned with the extension direction of the groove 31a. Therefore, as the rotary guide member 31 rotates, the connecting member 30b is pressed against one side surface or the other side surface of the groove 31a depending on the rotational direction of the rotary guide member 31, and is subjected to a circumferential force from the rotary guide member 31 in the rotational direction.

Therefore, when the rotary guide member 31 rotates, the connecting member 30b is pressed into the groove 31a of the rotary guide member 31, causing the holding member 30 to rotate together with the rotary guide member 31. Furthermore, the connecting member 30b is guided by the groove 31a of the rotary guide member 31, causing the holding member 30 to move back and forth along the axial direction of the driver bit 2.

The moving member 32 is an example of a transmission member and includes a first moving member 32a that rotates together with the holding member 30 and moves the holding member 30 back and forth along the rotation guide member 31, a second moving member 32c that is supported by the first moving member 32a via a bearing 32b and pushes the first moving member 32a via the bearing 32b, and a buffer member 32d attached to the rear side of the second moving member 32c.

The first moving member 32a is composed of, for example, a cylindrical member whose inner diameter is slightly larger than the outer diameter of the rotary guide member 31 and is placed on the outside of the rotary guide member 31. The first moving member 32a is connected to the holding member 30 via a connecting member 30b that protrudes from the groove portion 31a of the rotary guide member 31, and is supported so that it can move along the axial direction of the rotary guide member 31.

Bearing 32b is an example of a bearing, and is inserted between the outer periphery of first moving member 32a and the inner periphery of second moving member 32c. First moving member 32a constitutes a bearing inner ring holding member that holds the inner ring of bearing 32b, and second moving member 32c constitutes a bearing outer ring holding member that holds the outer ring of bearing 32b. The inner ring of bearing 32b is supported on the outer periphery of first moving member 32a so as to be unable to move in the rotational or axial direction, and the outer ring is supported on the inner periphery of second moving member 32c so as to be unable to move in the rotational or axial direction.

As a result, the second moving member 32c is connected to the first moving member 32a via the bearing 32b, with its movement in the forward and backward directions along the axial direction restricted. The second moving member 32c also rotatably supports the first moving member 32a via the bearing 32b.

Therefore, as the second moving member 32c moves back and forth along the axial direction, the first moving member 32a is pushed by the second moving member 32c via the bearing 32b, and moves back and forth along the axial direction together with the second moving member 32c. Furthermore, the first moving member 32a is rotatable relative to the second moving member 32c, which is non-rotatable relative to the rotation guide member 31.

In this example, the biasing member 33 is composed of a coil spring and is placed outside the rotation guide member 31 between the front frame 10b, which is provided on the front side of the case 10a of the tool body 10, and the second moving member 32c of the moving member 32, and abuts against a spring seat 32f arranged to contact the end face of the outer ring of the bearing 32b. The biasing member 33 is compressed when the moving member 32 moves forward as indicated by arrow A1, and applies a force to the moving member 32 that pushes it backward as indicated by arrow A2.

The first drive unit 4 includes a bit rotation motor 40 driven by electricity supplied from the battery 12, and a reduction gear 41. The bit rotation motor 40 is an example of a motor or first motor, and the shaft 40a of the bit rotation motor 40 is connected to the reduction gear 41, and the shaft 41a of the reduction gear 41 is connected to the rotation guide member 31. The first drive unit 4 has a configuration in which the reduction gear 41 utilizes a planetary gear, and the bit rotation motor 40 is arranged coaxially with the rotation guide member 31, the holding member 30, and the driver bit 2 held by the holding member 30.

The first drive unit 4 has a bit rotation motor 40 and a reducer 41 attached to a metal rear frame 10c provided on the rear side of the case 10a of the tool body 10, and the shaft 41a of the reducer 41 is supported by the rear frame 10c via a bearing 42. The rear end of the rotation guide member 31 is connected to the shaft 41a of the reducer 41, and the shaft 41a is supported by the rear frame 10c via the bearing 42, so that the rotation guide member 31 is rotatably supported via the bearing 42, which is an example of a bearing.

The bit holder 3 and first drive unit 4 are assembled together by connecting the front frame 10b and rear frame 10c with a connecting member 10d extending in the front-to-rear direction, and the front frame 10b is fixed to the case 10a of the tool body 10 with screws 10e.

The front end of the rotary guide member 31 of the bit holding unit 3 is supported via bearings 34a on the front frame 10b, which is fixed to the front side of the case 10a of the tool body 10, and the rear end of the rotary guide member 31 is supported via the shaft 41a of the reducer 41 and bearings 42 on the rear frame 10c, which is fixed to the rear side of the case 10a. Therefore, the rotary guide member 31 of the bit holding unit 3 is rotatably supported on the tool body 10.

As a result, the first drive unit 4 rotates the rotary guide member 31 using the bit rotation motor 40. When the rotary guide member 31 rotates, the holding member 30 that holds the driver bit 2 rotates together with the rotary guide member 31 as the connecting member 30b is pressed against the groove portion 31a of the rotary guide member 31.

The bit holder 3 has a guide member 32g attached to the second movable member 32c. The connecting member 10d has a pair of guide walls 10g spaced apart slightly larger than the diameter of the guide member 32g. By inserting the guide member 32g between the pair of guide walls 10g, the pair of guide walls 10g face the circumferential surface of the guide member 32g.

As a result, the second moving member 32c is able to move in the forward and backward directions indicated by arrows A1 and A2 along the axial direction of the driver bit 2, with the guide member 32g being guided by the connecting member 10d, while its rotation following the rotation guide member 31 is restricted.

Figures 6A and 6B are top cross-sectional views showing an example of the internal structure of the fastening tool of this embodiment, showing details of the second drive unit 5. Next, the second drive unit 5 will be described with reference to each figure.

The second drive unit 5 includes a bit moving motor 50 driven by electricity supplied from the battery 12, and a reducer 51. The bit moving motor 50 is an example of a motor or second motor, and the shaft 50a of the bit moving motor 50 is connected to the reducer 51, and the shaft 51a of the reducer 51 is connected to a pulley 52, which is an example of a transmission member. In the second drive unit 5, the pulley 52 is supported on the tool body 10 via a bearing 53. In the second drive unit 5, the shaft 50a of the bit moving motor 50 is arranged along the extension direction of the handle 11.

The second drive unit 5 has one end of a linear wire 54, an example of a transmission member, connected to a pulley 52, and the wire 54 is wound around the pulley 52 as the pulley 52 rotates. The other end of the wire 54 is connected to a wire connecting portion 32h provided on the second moving member 32c of the moving member 32.

As a result, the second drive unit 5 rotates the pulley 52 using the bit movement motor 50 and winds up the wire 54, moving the second moving member 32c forward as indicated by arrow A1. As the second moving member 32c moves forward, the first moving member 32a of the bit holding unit 3 is pushed via the bearing 32b, and the first moving member 32a moves forward along the axial direction together with the second moving member 32c. As the first moving member 32a moves forward, the holding member 30, which is connected to the first moving member 32a via the connecting member 30b, moves forward, and the driver bit 2 held by the holding member 30 moves forward as indicated by arrow A1.

The second drive unit 5 is positioned offset to one side of the approximate center in the left-right direction of the fastening tool 1 so that the tangent direction of the portion of the pulley 52 around which the wire 54 is wound is aligned with the extension direction of the rotary guide member 31. In other words, the center of the pulley 52, in this example the shaft 50a of the bit movement motor 50, is offset to one side relative to the rotary guide member 31, and when viewed axially of the pulley 52, the portion 52a of the pulley 52 around which the wire 54 is wound overlaps with the rotary guide member 31.

Furthermore, as shown in Figures 6A and 6B, the wire 54 between the pulley 52 and the second moving member 32c is parallel to the axial direction of the rotary guide member 31 in the radial direction of the pulley 52, and as shown in Figure 1A, the pulley 52 and other components are positioned so that the wire 54 is also parallel to the axial direction of the rotary guide member 31 in the axial direction of the bit moving motor 50, which is perpendicular to the radial direction of the pulley 52.

Furthermore, when the wire 54 is wound around the pulley 52 in overlapping layers, the distance from the center of the pulley 52 to the wire 54 changes depending on the number of turns, and therefore the amount of movement of the driver bit 2 when the pulley 52 makes one rotation changes. Also, the angle between the direction in which the wire 54 extends between the pulley 52 and the second moving member 32c and the direction in which the driver bit 2 moves along the axial direction of the rotation guide member 31 changes.

Therefore, the diameter, etc. of the pulley 52 are set so that the amount of rotation α of the pulley 52 required to move the driver bit 2 a predetermined amount is less than 360°.

As a result, when the pulley 52 winds the wire 54 to move the driver bit 2 a predetermined distance, the wire 54 does not overlap and overlaps with the pulley 52, as shown in Figure 6B, preventing the driver bit 2 from moving an inaccurate distance. Furthermore, changes in the parallelism between the direction in which the wire 54 extends between the pulley 52 and the second moving member 32c and the direction in which the driver bit 2 moves along the axial direction of the rotation guide member 31 are prevented.

Therefore, the relationship between the amount of rotation of the bit movement motor 50 and the amount of movement of the holding member 30 is one-to-one throughout the entire movable range of the holding member 30, and by controlling the amount of rotation of the bit movement motor 50, it is possible to control the amount of movement of the holding member 30 along the axial direction of the rotation guide member 31. In other words, by controlling the amount of rotation of the bit movement motor 50, it is possible to control the amount of movement of the driver bit 2 attached to the holding member 30.

In addition, regardless of the amount of winding of the wire 54, the tension applied to the wire 54 is always parallel to the movement direction of the driver bit 2 along the axial direction of the rotation guide member 31, thereby preventing a decrease in the movement of the driver bit 2 and the transmission efficiency of the force used to push the screw 200 via the driver bit 2.

This allows the wire 54 between the pulley 52 and the second moving member 32c to extend linearly along the direction of movement of the moving member 32, suppressing the increase in load when the wire 54 is wound around the pulley 52 and when the wire 54 is pulled out from the pulley 52.

In addition, because the wire 54 is flexible enough to be wound around the pulley 52, it cannot push against the second moving member 32c to move the moving member 32 backward. Therefore, a biasing member 33 is provided that compresses when the moving member 32 moves forward as indicated by arrow A1, and applies a force to the moving member 32 that pushes the moving member 32 backward as indicated by arrow A2. This allows the pulley 52 to wind up the wire 54, moving the driver bit 2 forward, and allowing the driver bit 2 to move backward after moving forward.

The holding member 30 that holds the driver bit 2 is supported so as to be movable in the front-to-rear direction relative to the rotary guide member 31 and rotates together with the rotary guide member 31 by the engagement between the connecting member 30b provided on the holding member 30 and the groove portion 31a provided on the rotary guide member 31.

Therefore, by arranging the bit rotation motor 40 coaxially with the rotation guide member 31, the holding member 30, and the driver bit 2 held by the holding member 30, it is possible to realize a configuration in which the driver bit 2 is rotated and moved in the forward and backward directions without moving the bit rotation motor 40 in the forward and backward directions.

In a configuration in which the bit rotation motor 40 is arranged coaxially with the driver bit 2, a feed screw can be used to convert the rotational movement of the bit rotation motor 40 into forward and backward movement of the driver bit 2.

However, with a configuration that uses a feed screw, the driver bit 2 cannot move forward a large distance per motor rotation, so even if the motor rotation speed is increased, it is difficult to increase the movement speed of the driver bit 2.

In fastening tool 1, the movement speed of driver bit 2 needs to be increased to shorten the time it takes for driver bit 2 to press screw 200 against the object to be fastened. However, with a configuration that uses a feed screw, it is difficult to shorten the time it takes for driver bit 2 to press screw 200 against the object to be fastened.

In contrast, in a configuration in which the holding member 30 that holds the driver bit 2 is supported so as to be movable forward and backward relative to the rotation guide member 31, and the second drive unit 5 rotates the pulley 52 to wind up the wire 54 and move the holding member 30 forward, the movement speed of the driver bit 2 can be increased according to the rotation speed of the bit movement motor 50. This reduces the time it takes for the driver bit 2 to press the screw 200 against the object to be fastened.

Figures 7A and 7B are cross-sectional views showing an example of a detachable holding mechanism, and Figures 8A and 8B are perspective views showing an example of a detachable holding mechanism, showing details of detachable holding mechanism 30c. Next, detachable holding mechanism 30c will be described with reference to these figures.

The detachable holding mechanism 30c includes a ball 30d exposed within the opening 30a and a spring 30e that biases the ball 30d in the direction of exposure within the opening 30a. The spring 30e is composed of an annular leaf spring and is fitted onto the outer periphery of the holding member 30.

When the insertion portion 20 of the driver bit 2 is inserted into the opening 30a of the holding member 30, the ball 30d of the detachable holding mechanism 30c is pushed by the insertion portion 20, deforming the annular spring 30e in a direction that increases the diameter of the spring 30e, and retracting toward the outer periphery of the holding member 30.

When the driver bit 2 insertion portion 20 is inserted into the opening 30a of the holding member 30 until the groove 20a formed on the outer periphery of the insertion portion 20 faces the ball 30d, the ball 30d, biased by the spring 30e, fits into the groove 20a. This prevents the driver bit 2 from accidentally coming out of the holding member 30.

Furthermore, when a force greater than a predetermined value is applied in the direction of removing the driver bit 2 from the holding member 30, the ball 30d retracts while deforming the annular spring 30e in a direction that increases its diameter, allowing the driver bit 2 to be removed from the holding member 30.

When the insertion portion 20 of the driver bit 2 is inserted into or removed from the opening 30a of the holding member 30, the ball 30d retreats toward the outer periphery of the holding member 30. Therefore, a space for the ball 30d to retreat to is required on the outer periphery of the holding member 30. However, the holding member 30 is inserted inside the cylindrical rotation guide member 31, and no space for the ball 30d to retreat to is available between the outer periphery of the holding member 30 and the inner periphery of the rotation guide member 31.

Furthermore, if a difference in diameter between the holding member 30 and the rotation guide member 31 is set to ensure a space for the ball 30d to retreat between the outer periphery of the holding member 30 and the inner periphery of the rotation guide member 31, the outer diameter of the holding member 30 cannot be reduced due to the fixed radial dimension of the driver bit 2, so the outer diameter of the rotation guide member 31 must be increased. This results in an increase in the size of the device.

In contrast, the rotary guide member 31 is provided with a groove 31a that guides the connecting member 30b. The groove 31a penetrates the rotary guide member 31 from the inner periphery to the outer periphery, and extends in the axial direction of the rotary guide member 31.

The detachable holding mechanism 30c is therefore arranged so that the ball 30d is aligned with the groove 31a of the rotary guide member 31. That is, the holding member 30 is arranged so that the connecting member 30b and the ball 30d of the detachable holding mechanism 30c are coaxially aligned along the axial direction of the rotary guide member 31. As a result, the ball 30d of the detachable holding mechanism 30c is exposed to the groove 31a of the rotary guide member 31 when the rotary guide member 31 and the holding member 30 rotate, or when the holding member 30 moves axially relative to the rotary guide member 31.

Therefore, when the insertion portion 20 of the driver bit 2 is inserted into or removed from the opening 30a of the holding member 30, the ball 30d, which retreats toward the outer periphery of the holding member 30, enters the groove 31a of the rotation guide member 31.

As a result, the holding member 30 is inserted into the cylindrical rotation guide member 31, ensuring space for the ball 30d of the detachable holding mechanism 30c to retreat. Furthermore, by using the groove 31a into which the connecting member 30b fits as a space for the ball 30d to retreat, the area of the opening provided in the rotation guide member 31 is reduced, ensuring strength.

Furthermore, there is no need to increase the diameter difference between the holding member 30 and the rotation guide member 31 to ensure space for the ball 30d to retreat between the outer periphery of the holding member 30 and the inner periphery of the rotation guide member 31, thereby preventing the device from becoming too large.

Figure 9 is a perspective view showing an example of the screw feed unit and nose unit of this embodiment, showing details of the screw feed unit 7 and nose unit 8. Next, the screw feed unit 7 and nose unit 8 will be described with reference to each figure.

The screw feed unit 7 includes a screw feed motor 70, a pinion gear 71 attached to the shaft of the screw feed motor 70 via a reducer, a rack gear 72 that meshes with the pinion gear 71, and an engagement unit 73 that is connected to the rack gear 72 and engages with the connecting screw fed from the screw storage unit 6.

The screw feed unit 7 supports a rack gear 72 that can move up and down along the feed direction of the connecting screw. When the screw feed motor 70 rotates forward and reverse, the engagement portion 73 that engages with the connecting screw moves up and down, feeding the connecting screw.

The nose portion 8 receives the screws 200 from the screw feed unit 7 and includes an injection passage 80 through which the driver bit 2 passes, a contact member 81 that has an injection port 81a that communicates with the injection passage 80 and comes into contact with the object to be fastened, a contact arm 82 that moves back and forth in conjunction with the contact member 81, and an adjustment unit 83 that regulates the amount of movement of the contact arm 82. The nose portion 8 also includes a cover member 88 that can be opened and closed to cover the path along which the screws 200 pass from the screw storage unit 6 to the injection passage 80.

The fastening tool 1 is constructed by assembling the components that make up the injection passage 80, contact member 81, and contact arm 82 to form the nose section 8, which is fixed to the front frame 10b and nose body section 10f that make up the tool body 10. The fastening tool 1 also includes a contact switch section 84 that is activated when pressed by the contact arm 82.

The nose portion 8 supports the contact member 81 so that it can move in the forward and backward directions indicated by arrows A1 and A2, and the contact arm 82 moves in the forward and backward directions in conjunction with the contact member 81. The contact member 81 of the nose portion 8 is biased forward by a biasing member (not shown), and the contact member 81, which is pressed against the object to be fastened and moves rearward, is then biased forward by the biasing member.

When the contact member 81 of the nose portion 8 is pressed against the object to be fastened, the contact arm 82 moves rearward, and the amount of movement of the contact arm 82 until the contact switch portion 84 is activated is adjusted by the adjustment portion 83. The contact switch portion 84 is activated or deactivated when pressed by the contact arm 82. In this example, the state in which the contact switch portion 84 is not pressed by the contact arm 82 and is inactivated is referred to as the off state of the contact switch portion 84, and the state in which the contact switch portion 84 is activated by being pressed by the contact arm 82 is referred to as the on state of the contact switch portion 84.

Next, the configuration related to the control and operation of the fastening tool 1 will be described with reference to the various figures. The fastening tool 1 is equipped with a trigger 9 that receives operation, and a trigger switch unit 90 that is activated by operating the trigger 9. The trigger 9 is provided on the front side of the handle 11 and is configured to be operable with the fingers of the hand holding the handle 11. The trigger switch unit 90 is activated when pressed by the trigger 9.

The trigger switch unit 90 is switched between activated and deactivated when pressed by the trigger 9. In this example, the trigger switch unit 90 is in an inactive state when the trigger 9 is not operated and the trigger 9 does not press the trigger switch unit 90, and is referred to as "off." The trigger switch unit 90 is in an activated state when the trigger 9 is operated and pressed by the trigger 9, and is referred to as "on."

The fastening tool 1 is equipped with a control unit 100 that controls the first drive unit 4, the second drive unit 5, and the screw feed unit 7 based on the outputs of a trigger switch unit 90 that is activated by operating the trigger 9 and a contact switch unit 84 that is activated by being pressed by a contact member 81.

The control unit 100 is composed of a circuit board on which various electronic components are mounted, and is located in the circuit board storage section 111, which is provided on the back side of the screw storage section 6, between the screw storage section 6 and the handle 11.

In power tools that are used by holding the handle in the hand, a storage compartment for screws and other consumables is located at the front of the handle. To be able to grip the handle with the hand, there needs to be enough space between the handle and the storage compartment for the fingers to fit in.

The fastening tool 1 therefore utilizes the space between the screw storage section 6 and the handle 11 to provide a board storage section 111 on the back side of the screw storage section 6.

For power tools that are used by holding the handle in the hand, a configuration has been proposed in which the battery is attached to the bottom of the handle and a circuit board is provided between the handle and the battery. With this configuration, the vertical dimension of the power tool increases along the extension direction of the handle.

In contrast, by providing the board storage section 111 on the back side of the screw storage section 6, the vertical dimension of the fastening tool 1, which is aligned with the extension direction of the handle 11, is prevented from expanding. Furthermore, because the screw storage section 6 stores spirally wound connecting screws, the surface of the screw storage section 6 facing the handle 11 is approximately circular. This ensures the capacity of the board storage section 111 while preventing the fastening tool 1 from becoming larger.

Figures 10A to 10C are perspective views from the rear showing an example of a fastening tool according to this embodiment, and Figure 11 is a perspective view showing an example of a setting unit, showing details of the setting unit 110. Next, the setting unit 110 will be described with reference to each figure.

The fastening tool 1 is equipped with a second drive unit 5 that moves the driver bit 2 forward and backward along the axial direction. The second drive unit 5 is driven by a bit movement motor 50, and a moving member 32 connected by a wire 54 to a pulley 52 driven and rotated by the bit movement motor 50, and a holding member 30 connected to the moving member 32, move forward along the axial direction of the driver bit 2 along a rotation guide member 31.

As a result, the movement amount (advancement amount) of the driver bit 2 can be controlled by controlling the rotation amount of the bit movement motor 50. In other words, by rotating the bit movement motor 50 in conjunction with the rotation of the bit rotation motor 40, which rotates the driver bit 2 in the direction to fasten the screw 200, the amount of advancement of the driver bit 2, which moves forward in response to the screw 200 as it is fastened, can be controlled by the rotation amount of the bit movement motor 50, and the stopping position of the driver bit 2 along the axial direction can be controlled.

The fastening tool 1 is therefore equipped with a setting unit 110 that sets the advance amount of the driver bit 2. The setting unit 110 is an example of a setting means, and is configured to allow any setting value to be selected from multiple setting values, or to allow any setting value to be selected continuously.

In this example, the setting unit 110 is configured so that a setting value is selected using the operation unit 110a, which is made up of buttons. Alternatively, the operation unit 110a may be configured so that a setting value is selected using a rotary dial. The setting unit 110 may also be configured to display the selected setting value by using a label or engraving, or by using a display unit 110b, such as an LED, to enable the operator to easily grasp the current setting value.

The setting section 110 is provided on both the left and right sides of the surface facing the handle 11 in the board storage section 111 provided on the back side of the screw storage section 6.

This makes it possible to see the setting section 110 from both the left and right sides of the handle 11 when viewing the fastening tool 1 from the rear.

When the handle 11 is held in the hand, the side of the screw storage section 6 facing the handle 11 faces the operator holding the fastening tool 1. Therefore, by providing the setting section 110 on the side of the board storage section 111 on the back side of the screw storage section 6 facing the handle 11, the display section 110b on the setting section 110 is more easily visible. This reduces the possibility that the operator will miss the display. The information displayed on the display section 110b includes the set screw depth, which is determined by the advancement amount of the driver bit 2, as well as the power ON/OFF status, the selected operating mode from the various selectable operating modes, the presence or absence of screws, the amount of remaining screws, and the presence or absence of any abnormalities.

In addition, when the handle 11 is held in one hand, the operation unit 110a, such as the buttons on the setting unit 110, is easily visible. Therefore, while holding the handle 11 in one hand, the operation unit 110a can be operated with the other hand while visually checking the operation unit 110a, ensuring reliable operation.

Furthermore, the board storage section 111 houses the board that constitutes the control unit 100. By mounting the switches that constitute the operation unit 110a and the lamps that constitute the display unit 110b on the surface of this board facing the handle 11, it is possible to omit a board for the setting unit 110 separate from the control unit 100.

Figure 12 is a block diagram showing an example of a fastening tool according to this embodiment. As described above, the fastening tool 1 includes a second drive unit 5 that moves the driver bit 2 back and forth along the axial direction, and the second drive unit 5 is driven by a bit movement motor 50. The holding member 30 to which the driver bit 2 is attached is connected to a movement member 32, which is connected by a wire 54 to a pulley 52 that is driven to rotate by the bit movement motor 50. The holding member 30 and movement member 32 then move forward along the axial direction of the driver bit 2 along the rotation guide member 31.

As a result, the control unit 100 can control the amount of movement (advancement) of the driver bit 2 by controlling the amount of rotation of the bit movement motor 50. In other words, by rotating the bit movement motor 50 in conjunction with the rotation of the bit rotation motor 40, which rotates the driver bit 2 in the direction of fastening the screw 200, the amount of advancement of the driver bit 2, which moves forward in response to the screw 200 as it is fastened, can be controlled by the amount of rotation of the bit movement motor 50, thereby controlling the stopping position of the driver bit 2 along the axial direction.

The control unit 100 also sets the rotation amount of the bit movement motor 50, which determines the advance amount of the driver bit 2, in the setting unit 110. Furthermore, the control unit 100 controls whether or not to drive the bit movement motor 50 of the second drive unit 5 and the bit rotation motor 40 of the first drive unit 4 based on the combination of on/off of the contact switch unit 84 and on/off of the trigger switch unit 90.

<Example of operation of the fastening tool according to this embodiment>
FIG. 13A is a side cross-sectional view showing an example of the operation of the fastening tool of this embodiment, FIG. 13B is a top cross-sectional view showing an example of the operation of the fastening tool of this embodiment, and FIG. 14 is a flowchart showing an example of the operation of the fastening tool of this embodiment. Next, the fastening operation of the fastening tool of this embodiment will be described with reference to each figure.

When the fastening tool 1 is in a standby state, as shown in Figure 1A, the tip of the driver bit 2 is located at standby position P1 behind the injection passage 80, and the screw 200 can be supplied to the injection passage 80.

In step SA1 of FIG. 14, the control unit 100 sets the rotation amount of the bit movement motor 50, which determines the advance amount of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact member 81 is pressed against the object to be fastened, the contact switch unit 84 is pressed by the contact arm 82, the contact switch unit 84 is turned on in step SA2, the trigger 9 is operated, and the trigger switch unit 90 is turned on in step SA3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SA4 and drives the bit movement motor 50 of the second drive unit 5 in step SA5.

When the bit movement motor 50 is driven to rotate in one direction, the forward direction, the pulley 52 rotates in the forward direction, causing the wire 54 to be wound around the pulley 52. As the wire 54 is wound around the pulley 52, the second moving member 32c connected to the wire 54 is guided by the rotation guide member 31 and moves forward along the axial direction. When the second moving member 32c moves forward, the first moving member 32a is pushed by the second moving member 32c via the bearing 32b, and moves forward along the axial direction together with the second moving member 32c while compressing the biasing member 33.

When the first moving member 32a moves forward, the holding member 30, which is connected to the first moving member 32a by the connecting member 30b, moves forward along the axial direction of the driver bit 2, with the connecting member 30b guided by the groove 31a of the rotation guide member 31.

As a result, the driver bit 2 held by the holding member 30 moves forward in the direction indicated by arrow A1, engaging with the screw 200 supplied to the injection port 81a of the nose portion 8 and moving the screw 200 forward, pressing it against the object to be fastened.

When the bit rotation motor 40 is driven to rotate in one direction, the forward direction, the rotation guide member 31 rotates in the forward direction. When the rotation guide member 31 rotates in the forward direction, the connecting member 30b connected to the holding member 30 is pressed against the groove portion 31a of the rotation guide member 31, causing the holding member 30 to rotate together with the rotation guide member 31.

As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction (clockwise) and screws it into the object to be fastened. The control unit 100, in conjunction with the operation of the first drive unit 4 to rotate the driver bit 2 and screw the screw into the object to be fastened, moves the driver bit 2 forward using the second drive unit 5 based on the load on the bit rotation motor 40, the rotation speed of the bit rotation motor 40, the load on the bit movement motor 50, the rotation speed of the bit movement motor 50, etc., causing the driver bit 2 to follow the screw being screwed into the object to be fastened.

When the control unit 100 determines in step SA6 that the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position P2 as shown in Figures 13A and 13B, it stops driving the bit rotation motor 40 in step SA7, stops the forward rotation of the bit movement motor 50 in step SA8, and then reverses the bit movement motor 50 in step SA9.

When the bit movement motor 50 rotates in the other direction, that is, in the reverse direction, the pulley 52 rotates in the reverse direction, causing the wire 54 to be pulled out from the pulley 52. When the wire 54 is pulled out from the pulley 52, the second moving member 32c moves forward, causing the compressed biasing member 33 to expand and push the second moving member 32c backward.

The second moving member 32c is pushed rearward by the biasing member 33, and is guided by the rotation guide member 31 to move rearward along the axial direction. When the second moving member 32c moves rearward, the first moving member 32a is pulled by the second moving member 32c via the bearing 32b, and moves rearward along the axial direction together with the second moving member 32c.

When the first moving member 32a moves rearward, the holding member 30, which is connected to the first moving member 32a by the connecting member 30b, moves rearward along the axial direction of the driver bit 2, with the connecting member 30b guided by the groove 31a of the rotation guide member 31.

In step SA10, the control unit 100 reverses the bit moving motor 50 to the initial position where a predetermined amount of wire 54 is pulled out from the pulley 52, and when the holding member 30 and moving member 32 move backward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SA11.

The moving member 32 is provided with a cushioning member 32d made of rubber or the like on the rear side of the second moving member 32c, which prevents the second moving member 32c from directly hitting the rear frame 10c when it moves rearward, thereby reducing noise and damage. When the trigger switch 90 is turned off, the control unit 100 rotates the screw feed motor 70 in one direction to lower the engagement portion 73. When the engagement portion 73 has lowered to a position where it engages with the next screw 200, the control unit 100 reverses the rotation of the screw feed motor 70 to raise the engagement portion 73 and supply the next screw 200 to the injection passage 80.

Figures 15A to 15C are cross-sectional views showing the screw fastening state. Figure 15A shows the so-called flush state in which the head 201 of the screw 200 is neither raised above nor buried in the surface of the object 202 to be fastened. Figure 15B shows the state in which the head 201 of the screw 200 is raised above the object 202 to be fastened. Figure 15C shows the state in which the head 201 of the screw 200 is buried in the object 202 to be fastened.

When the tip of the driver bit 2 reaches the operation end position P2, if the screw 200 is a flat head screw, the advancement amount of the driver bit 2 is preferably set so that the surface of the head 201 of the screw 200 is flush with the surface of the object 202 to be fastened, as shown in FIG. 15A. Note that the screw 200 is not limited to flat head screws. For pan head, bind, truss, and other types of screws, the advancement amount of the driver bit 2 is preferably set so that the seating surface of the head 201 of the screw 200 comes into contact with the surface of the object 202 to prevent the head 201 of the screw 200 from floating above the object 202.

When the tip of the driver bit 2 reaches the operation end position P2, if the head 201 of the screw 200 is floating above the object 202 to be fastened, as shown in FIG. 15B, the movement amount (advancement amount) of the driver bit 2 is set by the setting unit 110, and the number of rotations (amount of rotation) of the bit movement motor 50 is increased to increase the amount of advancement of the driver bit 2 and advance the operation end position P2. On the other hand, if the head 201 of the screw 200 is embedded in the object 202 to be fastened, as shown in FIG. 15C, the movement amount (advancement amount) of the driver bit 2 is set by the setting unit 110, and the number of rotations (amount of rotation) of the bit movement motor 50 is decreased to decrease the amount of advancement of the driver bit 2 and move the operation end position P2 back.

As mentioned above, the movement amount (advancement amount) of the driver bit 2 is determined by the number of rotations (amount of rotation) of the bit movement motor 50. Starting from standby position P1, which is the initial position of the driver bit 2, the bit movement motor 50 is rotated the amount of rotation set in the setting unit 110, and then the operation end position P2 is controlled by stopping or reversing the rotation of the bit movement motor 50. This makes it possible to adjust the tightening depth.

In this way, the standby positions of the holding member 30 to which the driver bit 2 is attached and the moving member 32 that moves the holding member 30 are set so that the tip position of the driver bit 2 held by the holding member 30 can move forward a predetermined amount based on the rotation amount of the bit moving motor 50, with a predetermined standby position P1 as the reference. The operation of setting the standby positions of the holding member 30 and the moving member 32 is referred to as the first initialization operation.

Then, before the driving and fastening operations begin, the holding member 30 and moving member 32 are moved to a set standby position, and the positions of the holding member 30 and moving member 32 are controlled by the amount of rotation of the bit moving motor 50, based on the standby position. The holding member 30 and moving member 32 are then advanced a predetermined amount (advancement amount) from the set standby position to perform the fastening operation. The operation of moving the holding member 30 and moving member 32 to the standby position set in the first initialization operation is referred to as the second initialization operation.

The standby positions of the holding member 30 and the moving member 32 during the first initialization operation can be set using a sensor or by using the maximum position within the range of forward and backward movement of the holding member 30 and the moving member 32 as a reference. If a sensor is used, the standby position is set to the position detected by the sensor or a position moved a specified distance from the detected position.

Furthermore, when using the maximum position in the range of forward and backward movement, the holding member 30 and the moving member 32 are set to a position moved a specified amount from the front end position or rear end position as the standby position.

Figures 16A to 16D are explanatory diagrams showing an example of the operation for setting the standby positions of the holding member and the moving member during the first initialization operation. Next, the operation for setting the standby positions of the holding member 30 and the moving member 32 will be described. Note that Figures 16A to 16D show an example of the operation for setting the standby positions using the maximum position within the range of forward and backward movement of the holding member 30 and the moving member 32.

As shown in FIG. 16A, the control unit 100 rotates the bit moving motor 50 in one direction, the forward direction, from a state in which the holding member 30 and the moving member 32 are in any position. When the bit moving motor 50 rotates forward, the wire 54 is wound around the pulley 52, causing the moving member 32 and the holding member 30 connected to the moving member 32 to move forward along the axial direction of the driver bit 2, along the rotation guide member 31.

As shown in FIG. 16B, when the bit moving motor 50 rotates forward until the holding member 30 and the moving member 32 move to the front end position PF, which is one of the end positions, the control unit 100 stops the forward rotation of the bit moving motor 50 and moves the holding member 30 and the moving member 32 to the front end position PF.

Next, the control unit 100 rotates the bit moving motor 50 in the other direction, that is, the reverse direction. When the bit moving motor 50 rotates in the reverse direction, the wire 54 is pulled out from the pulley 52, causing the biasing member 33 to push the moving member 32 rearward, and the moving member 32 and the holding member 30 connected to the moving member 32 move rearward along the axial direction of the driver bit 2, along the rotation guide member 31.

As shown in FIG. 16C, when the bit moving motor 50 rotates in the reverse direction until the holding member 30 and the moving member 32 reach the rear end position PE, which is the other end position, the control unit 100 stops the reverse rotation of the bit moving motor 50 and moves the holding member 30 and the moving member 32 to the rear end position PE by the biasing force of the biasing member 33.

The control unit 100 acquires the movement amount of the holding member 30 and the moving member 32 from the front end position PF to the rear end position PE as the total distance L1. The movement amount from the front end position PF to the rear end position PE is calculated from the rotation amount of the bit moving motor 50.

The control unit 100 presets the movement amount of the holding member 30 and the moving member 32 from the standby position to the front end position PF as the target movement amount L2. The control unit 100 sets the difference between the total distance L1 from the front end position PF to the rear end position PE and the preset target movement amount L2 as the standby position movement amount L3 and stores this. The standby position movement amount L3 is the movement amount of the holding member 30 and the moving member 32 from the rear end position PE.

As shown in FIG. 16D, the control unit 100 rotates the bit moving motor 50 in the forward direction, moving the holding member 30 and moving member 32 forward from the rear end position PE. After rotating the bit moving motor 50 in the forward direction a number of rotations (amount of rotations) equivalent to the standby position movement amount L3, the control unit 100 stops the forward rotation of the bit moving motor 50, moves the holding member 30 and moving member 32 to the standby position, and moves the tip of the driver bit 2 held by the holding member 30 to the standby position P1.

When moving the holding member 30 and the moving member 32 to the front end position PF and the rear end position PE, it is desirable to drive them at a low speed that does not affect the durability of the tool, for example, when the second moving member 32c hits the buffer member 32d.

Figures 17A to 17C are explanatory diagrams showing an example of the operation of moving the holding member and moving member to a standby position during the second initialization operation. Next, we will explain the operation of moving the holding member 30 and moving member 32 to a preset standby position.

As shown in FIG. 17A, the control unit 100 rotates the bit moving motor 50 in the other direction, that is, the reverse direction, when the holding member 30 and moving member 32 are in any position. When the bit moving motor 50 rotates in the reverse direction, the wire 54 is pulled out from the pulley 52, and the moving member 32 is pushed rearward by the biasing member 33. The moving member 32 and the holding member 30 connected to the moving member 32 move rearward along the axial direction of the driver bit 2, along the rotation guide member 31.

As shown in FIG. 17B, when the bit moving motor 50 rotates in the reverse direction until the holding member 30 and the moving member 32 reach the rear end position PE, the control unit 100 stops the reverse rotation of the bit moving motor 50 and moves the holding member 30 and the moving member 32 to the rear end position PE by the biasing force of the biasing member 33.

As shown in FIG. 17C, the control unit 100 rotates the bit moving motor 50 in the forward direction, moving the holding member 30 and moving member 32 forward from the rear end position PE. After rotating the bit moving motor 50 in the forward direction a number of rotations (amount of rotations) equivalent to the standby position movement amount L3, the control unit 100 stops the forward rotation of the bit moving motor 50, moves the holding member 30 and moving member 32 to the standby position, and moves the tip of the driver bit 2 held by the holding member 30 to the standby position P1.

In the first initialization operation described in Figures 16A to 16D, the operation of setting the standby positions of the holding member 30 and the moving member 32 is performed, for example, at the factory when the product is shipped, without user operation, and the standby position movement amount L3 is stored in advance.

On the other hand, in the second initialization operation described in Figures 17A to 17C, the operation of moving the holding member 30 and the moving member 32 to the standby position based on the standby position movement amount L3 is preferably performed each time the fastening tool 1 is powered on in order to ensure stable fastening operations.

Therefore, the system is configured to allow selection between a first initialization operation and a second initialization operation, which are initialization operations related to the standby positions of the holding member 30 and the moving member 32.

Figure 18 is a flowchart showing an example of the operation for selecting the first initialization operation and the second initialization operation.

When the control unit 100 is powered on in step SB1 of FIG. 18, it selects the initialization operation to be performed in step SB2. If the control unit 100 selects the first initialization operation, it performs the first initialization operation described above in FIGS. 16A to 16D in step SB3, setting the standby positions of the holding member 30 and the moving member 32. If the control unit 100 selects the second initialization operation, it performs the second initialization operation described above in FIGS. 17A to 17C in step SB4, moving the holding member 30 and the moving member 32 to their standby positions based on the standby position movement amount L3. After performing the second initialization operation, the control unit 100 performs the normal fastening operation in step SB5 in accordance with the flowchart of FIG. 14, etc.

As described above, in the first initialization operation, the holding member 30 and the moving member 32 are moved at a low speed from the front end position PF to the rear end position PE to obtain the total distance L1 from the front end position PF to the rear end position PE. The movement amount from the rear end position PE, determined so that the movement amount from the front end position PF is equal to the predetermined target movement amount L2, is set as the standby position movement amount L3 and recorded in memory on a circuit board (not shown) that constitutes the control unit 100. This eliminates various mechanical variations, such as dimensional differences within tolerances, and allows the standby positions of the holding member 30 and the moving member 32 to be set to a fixed position from the front end position PF, for example.

Furthermore, in the second initialization operation, the holding member 30 and the moving member 32 are moved from the rear end position PE to the standby position according to the standby position movement amount L3 each time the power is turned on for user use, thereby minimizing the movement amount of the holding member 30 and the moving member 32. Furthermore, in the second initialization operation, the tip of the driver bit 2 is positioned at the standby position P1 behind the injection passage 80, and the second initialization operation can be performed with the screw 200 supplied to the injection passage 80.

As described above, the movement amount (advancement amount) of the driver bit 2 is determined by the number of rotations (amount of rotations) of the bit movement motor 50, starting from the standby position of the holding member 30 and the moving member 32, i.e., the standby position P1 of the driver bit 2. Therefore, if the standby positions of the holding member 30 and the moving member 32, i.e., the standby position P1 of the driver bit 2, vary, the tightening depth set by the setting unit 110 will vary.

In contrast, by performing the second initialization operation each time the power is turned on, the bit movement motor 50 is rotated by the amount of rotation set by the setting unit 110, starting from the standby position of the holding member 30 and the moving member 32, i.e., the standby position P1 of the driver bit 2, thereby enabling accurate adjustment of the screw tightening depth.

Figure 19 is a flowchart showing a modified example of the operation of the fastening tool of this embodiment, and Figure 20 is a graph showing the relationship between the output of the contact switch unit and the control of the bit rotation motor and bit movement motor. Next, with reference to these figures, another example of the fastening operation of the fastening tool of this embodiment will be described. In this modified example, the output of the contact switch unit 84 detects whether the fastening tool 1 is lifting up relative to the object to be fastened, and the bit rotation motor 40 and bit movement motor 50 are controlled.

When the fastening tool 1 is in a standby state, as shown in Figure 1A, the tip of the driver bit 2 is located at standby position P1 behind the injection passage 80, and the screw 200 can be supplied to the injection passage 80.

In step SC1 of Figure 19, the control unit 100 sets the rotation amount of the bit movement motor 50, which determines the advance amount of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact member 81 is pressed against the object to be fastened, the contact arm 82 presses the contact switch unit 84, the contact switch unit 84 turns on in step SC2, the trigger 9 is operated, and the trigger switch unit 90 turns on in step SC3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SC4 and drives the bit movement motor 50 of the second drive unit 5 in step SC5.

When the bit movement motor 50 is driven to rotate in one direction, the forward direction, the pulley 52 rotates in the forward direction, winding the wire 54 around the pulley 52, and the second moving member 32c moves the moving member 32 connected to the wire 54, and the holding member 30 connected to the moving member 32 by the first moving member 32a, in the forward direction.

As a result, the driver bit 2 held by the holding member 30 moves forward in the direction indicated by arrow A1, engaging with the screw 200 supplied to the injection port 80 of the nose portion 8 and moving the screw 200 forward, pressing it against the object to be fastened.

Furthermore, when the bit rotation motor 40 is driven and rotates in one direction, the forward direction, the holding member 30 rotates together with the rotation guide member 31.

As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction (clockwise) and screws it into the object to be fastened. The control unit 100, in conjunction with the operation of the first drive unit 4 to rotate the driver bit 2 and screw the screw into the object to be fastened, moves the driver bit 2 forward using the second drive unit 5 based on the load on the bit rotation motor 40, the rotation speed of the bit rotation motor 40, the load on the bit movement motor 50, the rotation speed of the bit movement motor 50, etc., causing the driver bit 2 to follow the screw being screwed into the object to be fastened.

When the control unit 100 determines in step SC6 that the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position P2, it stops driving the bit movement motor 50 in step SC7.

When the control unit 100 stops driving the bit moving motor 50 in step SC7, it determines in step SC8 whether the contact switch unit 84 is on. If the contact switch unit 84 is on, the control unit 100 determines that the fastening tool 1 has not risen in a direction away from the fastening object, and to end the fastening operation, it stops the forward rotation of the bit rotation motor 40 in step SC9 and reverses the bit moving motor 50 in step SC10.

When the bit moving motor 50 rotates in the other direction, that is, in the reverse direction, the pulley 52 rotates in the reverse direction, causing the wire 54 to be pulled out from the pulley 52, and the second moving member 32c is pushed by the biasing member 33, causing the moving member 32 and the holding member 30 connected to the moving member 32 by the first moving member 32a to move backward.

In step SC11, the control unit 100 reverses the bit moving motor 50 to the initial position where a predetermined amount of wire 54 is pulled out from the pulley 52, and when the holding member 30 and moving member 32 move backward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SC12.

In step SC8, if the contact switch unit 84 is off, the control unit 100 determines that the fastening tool 1 is floating away from the object to be fastened, and continues to drive the bit rotation motor 40 to rotate in the forward direction while stopping the drive of the bit movement motor 50.

As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction, further screwing it into the object to be fastened, and the fastening tool 1 moves in a direction approaching the object to be fastened. This causes the fastening tool 1 to move relative to the contact arm 82, which presses the contact switch unit 84, turning it on. When the contact switch unit 84 is on, the control unit 100 executes the processing of steps SC9 to SC12 described above to end the fastening operation, stops the bit rotation motor 40, and reverses the bit movement motor 50 to return the driver bit 2 to its standby position.

In addition, while the contact switch unit 84 is turned off and the bit movement motor 50 is stopped, the control unit 100 performs a control operation known as a braking operation to prevent the bit movement motor 50 from rotating due to an external force while the bit rotation motor 40 is being rotated in the forward direction. This maintains the holding member 30, the moving member 32, and the driver bit 2 held by the holding member 30 stopped at the operation end position P2.

However, while the bit movement motor 50 is stopped and the bit rotation motor 40 is being rotated in the forward direction, the operator applies force to the fastening tool 1 in the direction that presses it against the object to be fastened, thereby tightening the screw 200. Therefore, even if the bit movement motor 50 is braked, the force applied by the operator may cause the holding member 30, the moving member 32, and the driver bit 2 held by the holding member 30 to move backward from the operation end position P2.

The control unit 100 then detects whether the bit moving motor 50 is rotating in the reverse direction in step SC13. If it detects that the bit moving motor 50 is rotating in the reverse direction, it returns to step SC5, rotates the bit moving motor 50 in the forward direction, moves the holding member 30 and the moving member 32 forward, and returns the driver bit 2 to the operation end position P2. It then stops the forward rotation of the bit moving motor 50 and performs a braking operation.

In order for the contact arm 82 to switch the contact switch unit 84 on and off, the contact arm 82 must move a predetermined amount. Therefore, as described above, in step SC8, when the contact switch unit 84 is detected to be off and the bit movement motor 50 is stopped, the bit rotation motor 40 continues to rotate in the forward direction until the contact switch unit 84 switches from off to on, and the positions of the holding member 30 and the moving member 32 may fluctuate during the movement of the contact arm 82. Therefore, it is desirable to provide a detection unit that detects the position of the contact arm 82. Note that a single motor may be used to rotate the bit holding unit 3 and move the bit holding unit 3 axially, and the control unit 100 may control the timing of stopping the drive of the single motor based on whether the contact switch unit 84 is activated.

FIG. 21 is a flowchart showing another modified example of the operation of the fastening tool of this embodiment, and FIG.
22A and 22B are graphs showing the relationship between the load and the control of the bit rotation motor. Next, with reference to these figures, another modification of the fastening operation of the fastening tool of this embodiment will be described. In this modification, the load applied to the bit rotation motor 40 is detected and the bit rotation motor 40 is controlled.

When the fastening tool 1 is in a standby state, as shown in Figure 1A, the tip of the driver bit 2 is located at standby position P1 behind the injection passage 80, and the screw 200 can be supplied to the injection passage 80.

In step SD1 of FIG. 21, the control unit 100 sets the rotation amount of the bit movement motor 50, which determines the advance amount of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact member 81 is pressed against the object to be fastened, the contact switch unit 84 is pressed by the contact arm 82, the contact switch unit 84 is turned on in step SD2, the trigger 9 is operated, and the trigger switch unit 90 is turned on in step SD3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SD4 and drives the bit movement motor 50 of the second drive unit 5 in step SD5.

When the bit movement motor 50 is driven to rotate in one direction, the forward direction, the pulley 52 rotates in the forward direction, winding the wire 54 around the pulley 52, and the second moving member 32c moves the moving member 32 connected to the wire 54, and the holding member 30 connected to the moving member 32 by the first moving member 32a, in the forward direction.

As a result, the driver bit 2 held by the holding member 30 moves forward in the direction indicated by arrow A1, engaging with the screw 200 supplied to the injection port 80 of the nose portion 8 and moving the screw 200 forward, pressing it against the object to be fastened.

Furthermore, when the bit rotation motor 40 is driven and rotates in one direction, the forward direction, the holding member 30 rotates together with the rotation guide member 31.

As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction (clockwise) and screws it into the object to be fastened. The control unit 100, in conjunction with the operation of the first drive unit 4 to rotate the driver bit 2 and screw the screw into the object to be fastened, moves the driver bit 2 forward using the second drive unit 5 based on the load on the bit rotation motor 40, the rotation speed of the bit rotation motor 40, the load on the bit movement motor 50, the rotation speed of the bit movement motor 50, etc., causing the driver bit 2 to follow the screw being screwed into the object to be fastened.

In step SD6, the control unit 100 determines whether the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and whether the tip of the driver bit 2 has reached the set operation end position P2. If the control unit 100 determines that the rotation amount of the bit movement motor 50 has not reached the set value selected by the setting unit 110, it detects the load on the bit rotation motor 40 in step SD7, and if it detects a predetermined load, it controls the bit rotation motor 40 in step SD8.

Differences in the rotation speed of the driver bit 2 occur depending on the load on the bit rotation motor 40, and if the current and voltage values applied to the bit rotation motor 40 are the same, the higher the load on the bit rotation motor 40, the slower the rotation speed. Therefore, the control unit 100, as a fluctuation detection unit that detects factors that cause fluctuations in the rotation speed of the bit rotation motor 40, detects the load on the bit rotation motor 40, and reduces the output of the bit rotation motor 40 by, for example, lowering the voltage value applied to the bit rotation motor 40 or the current value flowing through the bit rotation motor 40 when the load on the bit rotation motor 40 is lower compared to when the load is higher.

As a result, when the load on the bit rotation motor 40 is light, the rotation speed of the bit rotation motor 40 is reduced, preventing the rotation speed from becoming too high compared to when the load is high, and preventing differences in the rotation speed of the bit rotation motor 40 due to the magnitude of the load on the bit rotation motor 40. This prevents variations in the speed at which the screws 200 are fastened.

When the control unit 100 determines in step SD6 that the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position P2, it stops driving the bit rotation motor 40 in step SD9, stops the forward rotation of the bit movement motor 50 in step SD10, and then reverses the bit movement motor 50 in step SD11.

When the bit moving motor 50 rotates in the other direction, that is, in the reverse direction, the pulley 52 rotates in the reverse direction, causing the wire 54 to be pulled out from the pulley 52, and the second moving member 32c is pushed by the biasing member 33, causing the moving member 32 and the holding member 30 connected to the moving member 32 by the first moving member 32a to move backward.

In step SD12, the control unit 100 reverses the bit moving motor 50 to its initial position where a predetermined amount of wire 54 is pulled out from the pulley 52, and when the holding member 30 and moving member 32 move backward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SD13.

In controlling the reduction of the output of the bit rotation motor 40, as shown in Figure 22A, after a predetermined load is detected, the output may be reduced so that a constant rotation speed is maintained until the driver bit 2 moves to the operation end position and the bit rotation motor 40 rotates.Alternatively, as shown in Figure 22B, after a predetermined load is detected, the output may be gradually reduced so that a target rotation speed is maintained until the driver bit 2 moves to the operation end position and the bit rotation motor 40 rotates.

Fluctuation in the power supply voltage causes differences in the rotation speed of the driver bit 2, with the lower the power supply voltage, the slower the rotation speed. Therefore, the control unit 100, acting as a fluctuation detection unit that detects factors that cause fluctuations in the rotation speed of the bit rotation motor 40, detects the power supply voltage, and when the power supply voltage is high, the output of the bit rotation motor 40 is reduced compared to when the power supply voltage is low.

As a result, when the power supply voltage is high, the rotation speed of the bit rotation motor 40 is reduced compared to when the power supply voltage is low, thereby preventing differences in the rotation speed of the bit rotation motor 40 due to fluctuations in the power supply voltage. This prevents variations in the speed at which the screws 200 are fastened.

In addition, the control unit 100 may set a target rotation speed for the bit rotation motor 40, detect the rotation speed of the bit rotation motor 40, compare the detected rotation speed of the bit rotation motor 40 with a preset target rotation speed of the bit rotation motor 40, and control the bit rotation motor 40 so that the target rotation speed is achieved.

Now, reducing the rotational speed of the bit rotation motor 40 causes a decrease in the speed at which the screw is fastened into the object to be fastened. On the other hand, during the process of stopping the bit rotation motor 40 after the screw has been fastened to the target screw fastening depth set by the setting unit 110, the driver bit 2 continues to rotate, fastening the screw into the object to be fastened, until the rotation of the bit rotation motor 40 completely stops. For this reason, the faster the rotational speed of the bit rotation motor 40 immediately before it stops, the more the screw will be fastened beyond the target.

As such, the reason why the quality of screw tightening work is reduced due to differences in the rotational speed of the bit rotation motor 40 is due to the rotational speed of the bit rotation motor 40 just before it stops rotating. Therefore, the desired effect can be achieved if the rotational speed of the bit rotation motor 40 is constant, eliminating the influence of load, just before the movement amount (advancement amount) of the holding member 30 and the moving member 32 reaches the target screw tightening depth set in the setting unit 110.

The load on the bit rotation motor 40 increases when the screw begins to be tightened into the object to be fastened, but the load varies depending on the material of the object to be fastened, etc. Therefore, after the load detection described above for controlling the rotation speed of the bit rotation motor 40, the rotation speed of the bit rotation motor 40 is controlled based on the load, power supply voltage, etc., until the target screw tightening depth is reached.

The control unit 100 may be provided with a timer, and after a predetermined time has elapsed since the bit rotation motor 40 started to rotate (forward), the control unit 100 may execute the above-mentioned control of the rotation speed of the bit rotation motor 40 based on the load, power supply voltage, etc. Furthermore, the control unit 100 may be provided with a position detection unit that detects the positions of the holding member 30 and the moving member 32, and after the holding member 30 and the moving member 32 reach a predetermined position, the control unit 100 may execute the above-mentioned control of the rotation speed of the bit rotation motor 40 based on the load, power supply voltage, etc. The predetermined positions of the holding member 30 and the moving member 32 for controlling the rotation speed of the bit rotation motor 40 are set between the position where the above-mentioned load for controlling the rotation speed of the bit rotation motor 40 is detected and the position where the target screw drive depth is reached.

Furthermore, in a method of setting a target rotational speed for the bit rotating motor 40 and controlling the output, it is possible that the target screw tightening depth will be reached before the rotational speed of the bit rotating motor 40 decreases to the target rotational speed, due to factors such as the length of the control implementation period. Therefore, braking control of the bit rotating motor 40 may be performed during control to decrease the rotational speed of the bit rotating motor 40 to the target rotational speed. For example, if there is a large deviation between the target rotational speed of the bit rotating motor 40 and the detected actual rotational speed, braking control of the bit rotating motor 40 may be performed until the deviation between the actual rotational speed and the target rotational speed falls within a specified range, and once this deviation falls within the specified range, control may be performed to decrease the rotational speed of the bit rotating motor 40 to the target rotational speed.

Furthermore, if the driver bit 2 disengages from the screw after reaching the target screw drive depth, the screw will not be further tightened even if the driver bit 2 rotates. Therefore, after the driver bit 2 has advanced until it reaches the target screw drive depth, the bit movement motor 50 may be reversed before the bit rotation motor 40 stops rotating. Furthermore, a single motor may be used to rotate the bit holder 3 and move it axially, and the control unit 100 may detect factors that cause fluctuations in the rotational speed of the single motor, such as the load on the motor, and control the motor accordingly.

Figure 23 is a flowchart showing another modified example of the operation of the fastening tool of this embodiment, Figure 24A is a graph showing the relationship between the rotational speeds of the bit rotation motor and the bit movement motor under feedback (FB) control, and Figure 24B is a graph showing the relationship between the screw movement speed due to the rotation of the bit rotation motor under feedback (FB) control and the driver bit movement speed due to the bit movement motor. Next, with reference to these figures, another modified example of the fastening operation of the fastening tool of this embodiment will be described. In this modified example, the screw movement speed due to the rotation of the bit rotation motor 40 and the driver bit movement speed due to the bit movement motor 50 are synchronized by feedback control.

When the fastening tool 1 is in a standby state, as shown in Figure 1A, the tip of the driver bit 2 is located at standby position P1 behind the injection passage 80, and the screw 200 can be supplied to the injection passage 80.

In step SE1 of Figure 23, the control unit 100 sets the rotation amount of the bit movement motor 50, which determines the advance amount of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact member 81 is pressed against the object to be fastened, the contact switch unit 84 is pressed by the contact arm 82, the contact switch unit 84 is turned on in step SE2, the trigger 9 is operated, and the trigger switch unit 90 is turned on in step SE3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SE4 and drives the bit movement motor 50 of the second drive unit 5 in step SE5.

When the bit movement motor 50 is driven to rotate in one direction, the forward direction, the pulley 52 rotates in the forward direction, winding the wire 54 around the pulley 52, and the second moving member 32c moves the moving member 32 connected to the wire 54, and the holding member 30 connected to the moving member 32 by the first moving member 32a, in the forward direction.

As a result, the driver bit 2 held by the holding member 30 moves forward in the direction indicated by arrow A1, engaging with the screw 200 supplied to the injection port 80 of the nose portion 8 and moving the screw 200 forward, pressing it against the object to be fastened.

Furthermore, when the bit rotation motor 40 is driven and rotates in one direction, the forward direction, the holding member 30 rotates together with the rotation guide member 31.

As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction (clockwise) and screws it into the object to be fastened. The control unit 100 rotates the driver bit 2 with the first drive unit 4 to rotate the screw into the object to be fastened, and moves the driver bit 2 forward with the second drive unit 5, causing the driver bit 2 to follow the screw being screwed into the object to be fastened.

In step SE6, the control unit 100 determines whether the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and whether the tip of the driver bit 2 has reached the set operation end position P2. If the control unit 100 determines that the rotation amount of the bit movement motor 50 has not reached the set value selected by the setting unit 110, it detects the load on the bit movement motor 50 in step SE7, and if it detects a predetermined load, it acquires the rotation speed of the bit rotation motor 40 and the rotation speed of the bit movement motor 50 in step SE8.

In step SE9, the control unit 100 calculates the rotational speeds of the bit rotation motor 40 and the bit movement motor 50 based on the rotational speeds of the bit rotation motor 40, the rotational speeds of the bit movement motor 50, the gear ratio of the reducer, etc., so that the movement speed of the screw 200 moving forward as the screw 200 is fastened into the object by the rotation of the bit rotation motor 40, and the movement speed of the holding member 30 and the moving member 32 moving forward by the rotation of the bit movement motor 50, and the driver bit 2 attached to the holding member 30, approximately match as shown in FIG. 24B.

In step SE10, the control unit 100 controls the bit movement motor 50 in this example using feedback control based on the rotation speed of the bit rotation motor 40, the rotation speed of the bit movement motor 50, the gear ratio of the reducer, etc. For example, control is performed by increasing or decreasing the PWM output to the bit movement motor 50 to adjust the rotation speed.

When the control unit 100 determines in step SE6 that the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position P2, it stops driving the bit rotation motor 40 in step SE11, stops the forward rotation of the bit movement motor 50 in step SE12, and then reverses the bit movement motor 50 in step SE13.

When the bit moving motor 50 rotates in the other direction, that is, in the reverse direction, the pulley 52 rotates in the reverse direction, causing the wire 54 to be pulled out from the pulley 52, and the second moving member 32c is pushed by the biasing member 33, causing the moving member 32 and the holding member 30 connected to the moving member 32 by the first moving member 32a to move backward.

In step SE14, the control unit 100 reverses the bit moving motor 50 to its initial position where a predetermined amount of wire 54 is pulled out from the pulley 52, and when the holding member 30 and moving member 32 move backward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SE15.

The feedback control described above is required after the screw 200 comes into contact with the object to be fastened and the load on the bit rotation motor 40 and bit movement motor 50 changes. Therefore, control when feedback control is not being performed is designated as the first control mode, and control when feedback control is being performed is designated as the second control mode. The first control mode is executed before a predetermined load is detected by either the bit rotation motor 40 or the bit movement motor 50, or both. Then, when a predetermined load is detected by either the bit rotation motor 40 or the bit movement motor 50, or both, the first control mode is switched to the second control mode, and the second control mode is executed. This reduces delays in work time.

Furthermore, as a means of improving feedback control responsiveness and achieving more stable work quality, the acceleration/deceleration limit value for the bit movement motor 50 may be changed between when feedback control is being executed after load detection and when feedback control is not being executed before load detection. Normally, when PWM output is performed on the motor, control is executed to prevent the acceleration current, particularly at startup, from becoming excessive by limiting the acceleration amount per unit time in order to stabilize the motor output. However, if the above-mentioned feedback control is executed while limiting the acceleration at startup of the bit movement motor 50, the PWM output generated by the feedback control will be limited and applied to the bit movement motor 50, resulting in poor responsiveness to feedback control. Therefore, it is desirable to set the acceleration limit amount larger during feedback control than when the motor is started without feedback control.

Figure 25 is a flowchart showing another modified example of the operation of the fastening tool of this embodiment, and Figures 26A and 26B are graphs showing the relationship between the load and the control of the bit moving motor. Next, with reference to these figures, another modified example of the fastening operation of the fastening tool of this embodiment will be described. In this modified example, the load applied to the bit moving motor 50 is detected and the bit moving motor 50 is controlled.

When the fastening tool 1 is in a standby state, as shown in Figure 1A, the tip of the driver bit 2 is located at standby position P1 behind the injection passage 80, and the screw 200 can be supplied to the injection passage 80.

In step SF1 of Figure 25, the control unit 100 sets the rotation amount of the bit movement motor 50, which determines the advance amount of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact member 81 is pressed against the object to be fastened, the contact arm 82 presses the contact switch unit 84, the contact switch unit 84 turns on in step SF2, the trigger 9 is operated, and the trigger switch unit 90 turns on in step SF3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SF4 and drives the bit movement motor 50 of the second drive unit 5 in step SF5.

When the bit movement motor 50 is driven to rotate in one direction, the forward direction, the pulley 52 rotates in the forward direction, winding the wire 54 around the pulley 52, and the second moving member 32c moves the moving member 32 connected to the wire 54, and the holding member 30 connected to the moving member 32 by the first moving member 32a, in the forward direction.

As a result, the driver bit 2 held by the holding member 30 moves forward in the direction indicated by arrow A1, engaging with the screw 200 supplied to the injection port 80 of the nose portion 8 and moving the screw 200 forward, pressing it against the object to be fastened.

Furthermore, when the bit rotation motor 40 is driven and rotates in one direction, the forward direction, the holding member 30 rotates together with the rotation guide member 31.

As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction (clockwise) and screws it into the object to be fastened. The control unit 100 rotates the driver bit 2 with the first drive unit 4 to rotate the screw into the object to be fastened, and moves the driver bit 2 forward with the second drive unit 5, causing the driver bit 2 to follow the screw being screwed into the object to be fastened.

In step SF6, the control unit 100 determines whether the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and whether the tip of the driver bit 2 has reached the set operation end position P2. If the control unit 100 determines that the rotation amount of the bit movement motor 50 has not reached the set value selected by the setting unit 110, it detects the load on the bit movement motor 50 in step SF7, and if it detects a predetermined load, it controls the bit movement motor 50 in step SF8.

When the bit movement motor 50 is driven, the holding member 30 and the moving member 32 move forward, pressing the screw 200 against the object to be fastened. In order to prevent excessive impact, the bit rotation motor 40 operates at the maximum output within the expected range and does not reduce the fastening speed. At the same time, the output of the bit movement motor 50 is limited by reducing the voltage applied to the bit movement motor 50, reducing the current flowing through the bit movement motor 50, etc.

When the ratio of the advance of the driver bit 2 per rotation of the bit movement motor 50 to the advance of the screw per rotation of the bit rotation motor 40 becomes low, the advance of the driver bit 2 caused by the bit movement motor 50 cannot keep up with the advance of the screw caused by the bit rotation motor 40, resulting in cam-out. On the other hand, when the ratio of the advance of the driver bit 2 per rotation of the bit movement motor 50 to the advance of the screw per rotation of the bit rotation motor 40 becomes high, the advance of the driver bit 2 caused by the bit movement motor 50 greatly exceeds the advance of the screw caused by the bit rotation motor 40, requiring the operator to exert excessive force to press the fastening tool 1 toward the object to be fastened.

Therefore, it is preferable that the target value for the output limit be a ratio of the driver bit 2 advancement amount per rotation of the bit movement motor 50 to the screw advancement amount per rotation of the bit rotation motor 40, which is approximately 0.8 to 5 times. This prevents cam-out from occurring and also prevents excessive impact when the screw 200 is pressed against the object to be fastened, without the operator needing to use excessive force to press the fastening tool 1 toward the object to be fastened.

In addition, when the load on the bit movement motor 50 that occurs after contact between the object to be fastened and the screw 200 is detected, the output of the bit movement motor 50 is limited, thereby slowing down the holding member 30 and the moving member 32 when the screw 200 is pressed against the object to be fastened, thereby achieving further impact suppression effects.

In controlling the output of the bit movement motor 50, as shown in FIG. 26A, after a predetermined load is detected, the output of the bit movement motor 50 may be limited so that the bit movement motor 50 maintains a constant rotational speed until the bit rotation motor 40 rotates and the driver bit 2 moves to the end of operation position. Also, as shown in FIG. 26B, the bit movement motor 50 rotates forward at a first rotational speed until the predetermined load is detected. After the predetermined load is detected, the bit movement motor 50 rotates forward at a lower second rotational speed to reduce the impact when the screw 200 is pressed against the object to be fastened. Furthermore, after a predetermined buffer time has elapsed during which the impact when the screw 200 is pressed against the object to be fastened is reduced, the output may be limited so that the driver bit 2 maintains a constant rotational speed until the bit rotation motor 40 rotates and the driver bit 2 moves to the end of operation position at a third rotational speed that is slower than the first rotational speed but faster than the second rotational speed.

Fluctuation in the power supply voltage causes differences in the movement speed (forward speed) of the holding member 30 and the moving member 32; the higher the power supply voltage, the faster the movement speed, making it more likely that excessive impact will occur when the screw 200 is pressed against the object to be fastened. Therefore, the control unit 100 detects the power supply voltage, and when the power supply voltage is high, it reduces the output of the bit moving motor 50 compared to when the power supply voltage is low.

This prevents differences in the rotational speed of the bit movement motor 50 due to fluctuations in the power supply voltage. This prevents excessive impact when the screw 200 is pressed against the object to be fastened, and also prevents variations in the speed at which the screw 200 is pressed against the object to be fastened.

When the control unit 100 determines in step SF6 that the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position P2, it stops driving the bit rotation motor 40 in step SF9, stops the forward rotation of the bit movement motor 50 in step SF10, and then reverses the bit movement motor 50 in step SF11.

When the bit moving motor 50 rotates in the other direction, that is, in the reverse direction, the pulley 52 rotates in the reverse direction, causing the wire 54 to be pulled out from the pulley 52, and the second moving member 32c is pushed by the biasing member 33, causing the moving member 32 and the holding member 30 connected to the moving member 32 by the first moving member 32a to move backward.

In step SF12, the control unit 100 reverses the bit moving motor 50 to the initial position where a predetermined amount of wire 54 is pulled out from the pulley 52, and when the holding member 30 and moving member 32 move backward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SF13.

Figure 27 is a flowchart showing another modified example of the operation of the fastening tool of this embodiment. Next, with reference to the respective figures, another modified example of the fastening operation of the fastening tool of this embodiment will be described. In this modified example, the load on the bit moving motor 50, etc. is detected, and driving when there is no screw is suppressed.

When the fastening tool 1 is in a standby state, as shown in Figure 1A, the tip of the driver bit 2 is located at standby position P1 behind the injection passage 80, and the screw 200 can be supplied to the injection passage 80.

In step SG1 of Figure 27, the control unit 100 sets the rotation amount of the bit movement motor 50, which determines the advance amount of the driver bit 2, based on the setting value selected by the setting unit 110. When the contact member 81 is pressed against the object to be fastened, the contact switch unit 84 is pressed by the contact arm 82, the contact switch unit 84 is turned on in step SG2, the trigger 9 is operated, and the trigger switch unit 90 is turned on in step SG3, the control unit 100 drives the bit rotation motor 40 of the first drive unit 4 in step SG4 and drives the bit movement motor 50 of the second drive unit 5 in step SG5.

When the bit movement motor 50 is driven to rotate in one direction, the forward direction, the pulley 52 rotates in the forward direction, winding the wire 54 around the pulley 52, and the second moving member 32c moves the moving member 32 connected to the wire 54, and the holding member 30 connected to the moving member 32 by the first moving member 32a, in the forward direction.

As a result, the driver bit 2 held by the holding member 30 moves forward in the direction indicated by arrow A1, engaging with the screw 200 supplied to the injection port 80 of the nose portion 8 and moving the screw 200 forward, pressing it against the object to be fastened.

Furthermore, when the bit rotation motor 40 is driven and rotates in one direction, the forward direction, the holding member 30 rotates together with the rotation guide member 31.

As a result, the driver bit 2 held by the holding member 30 rotates the screw 200 in the forward direction (clockwise) and screws it into the object to be fastened. The control unit 100 rotates the driver bit 2 with the first drive unit 4 to rotate the screw into the object to be fastened, and moves the driver bit 2 forward with the second drive unit 5, causing the driver bit 2 to follow the screw being screwed into the object to be fastened.

In step SG6, the control unit 100 determines whether the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and whether the tip of the driver bit 2 has reached the set operation end position P2. If the control unit 100 determines that the rotation amount of the bit movement motor 50 has not reached the set value selected by the setting unit 110, then in step SG7, it detects the load on either the bit rotation motor 40 or the bit movement motor 50, or both. When a predetermined load is detected as the screw 200 is pressed against the object to be fastened, the bit movement motor 50 continues to rotate in the forward direction until the rotation amount of the bit movement motor 50 reaches the set value selected by the setting unit 110.

When the control unit 100 determines in step SG6 that the rotation amount of the bit movement motor 50 has reached the set value selected by the setting unit 110 and that the tip of the driver bit 2 has reached the set operation end position P2, it stops driving the bit rotation motor 40 in step SG8, stops the forward rotation of the bit movement motor 50 in step SG9, and then reverses the bit movement motor 50 in step SG10.

When the bit moving motor 50 rotates in the other direction, that is, in the reverse direction, the pulley 52 rotates in the reverse direction, causing the wire 54 to be pulled out from the pulley 52, and the second moving member 32c is pushed by the biasing member 33, causing the moving member 32 and the holding member 30 connected to the moving member 32 by the first moving member 32a to move backward.

In step SG11, the control unit 100 reverses the bit moving motor 50 to the initial position where a predetermined amount of wire 54 is pulled out from the pulley 52, and when the holding member 30 and moving member 32 move backward to a position where the tip of the driver bit 2 returns to the standby position P1, the control unit 100 stops the reverse rotation of the bit moving motor 50 in step SG12.

When the bit rotation motor 40 and bit movement motor 50 are rotated in the forward direction when there is no screw 200 in the injection port 80, the screw 200 is not pressed against the object to be fastened, and therefore the load on the bit rotation motor 40 and bit movement motor 50 does not increase. Therefore, even if the driver bit 2 attached to the holding member 30 moves forward a specified amount based on the length of the smallest screw 200 to be loaded, if the specified load is not detected, it can be determined that there is no screw 200.

Then, in step SG13, the control unit 100 determines whether the bit movement motor 50 has rotated a specified amount based on the length of the smallest screw 200 to be loaded, the specified amount of idling detection by which the driver bit 2 attached to the holding member 30 advances. If the control unit 100 determines that the specified load has not been detected by either the bit rotation motor 40 or the bit movement motor 50, or both, and that the bit movement motor 50 has rotated the specified amount of idling detection, it determines that there are no screws 200 and issues an error notification in step SG14. Furthermore, the control unit 100 stops driving the bit rotation motor 40 and bit movement motor 50 by processing steps SG8 to SG12 described above.

The control unit 100 may detect the load on either the bit rotation motor 40 or the bit movement motor 50, or both, based on changes in the current flowing through the motor, excluding changes in current that occur when the motor is started. Alternatively, the control unit 100 may detect the load on either the bit rotation motor 40 or the bit movement motor 50 based on changes in voltage across the motor, excluding changes in voltage that occur when the motor is started. A single motor may be used to rotate the bit holder 3 and move the bit holder 3 axially, and the control unit 100 may detect the load on the single motor and suppress driving it when no screws are present.

1: Fastening tool, 10: Tool body, 10a: Case, 10b: Front frame, 10c: Rear frame, 10d: Connecting member, 10e: Screw, 10f: Nose body, 11: Handle, 12: Battery, 13: Battery mounting portion, 2: Driver bit, 3: Bit holding portion, 30: Holding member, 30a: Opening, 30b: Connecting member, 31: Rotation guide member, 31a: Groove portion, 32: Moving member, 32a: First moving member, 32b: Bearing, 32c: Second moving member, 33: Pressing member, 34a: Bearing, 4: First drive unit, 40: Bit rotation motor (motor, first motor), 40a: Shaft, 41 ...Reduction gear, 41a...shaft, 42...bearing (bearing), 5...second drive unit, 50...bit movement motor (motor, second motor), 50a...shaft, 51...reduction gear, 51a...shaft, 52...pulley (transmission member), 53...bearing, 54...wire (transmission member), 6...screw storage unit, 7...screw feed unit, 70...screw feed motor, 71...pinion gear, 72...rack gear, 73...engagement unit, 8...nose unit, 80...injection passage, 81...contact member, 81a...injection port, 82...contact arm, 83...adjustment unit, 84...contact switch unit, 9...trigger, 90...trigger switch unit, 100...control unit, 110...setting unit

Claims (8)

a bit holding portion that detachably holds a driver bit and is rotatable in a circumferential direction of the driver bit and movable in an axial direction;
a motor that rotates the bit holding portion and moves the bit holding portion along an axial direction;
a control unit that controls the axial position of the bit holding unit by the rotation amount of the motor,
The control unit limits the output of the motor when detecting a load applied to the motor that is rotated in one direction to move the bit holding unit toward the object to be fastened,
The fastening tool stops rotation of the motor when it is determined that there is no screw based on the load applied to the motor . The fastening tool according to claim 1 , wherein, when the control unit stops the rotation of the motor, the control unit causes the motor to rotate in another direction to move the bit holding unit in a direction away from the object to be fastened. The fastening tool according to claim 1 or 2, wherein the control unit notifies the user of an abnormality when the rotation of the motor is stopped. The fastening tool according to any one of claims 1 to 3, wherein the control unit determines whether or not a screw is present based on a load applied to the motor, and stops rotation of the motor when it determines that a screw is not present. The fastening tool according to claim 4, wherein the control unit determines whether a screw is present or not based on a movement amount based on a minimum screw length and a load applied to the motor when the bit holding unit moves in one direction. The fastening tool according to any one of claims 1 to 5, wherein the load on the motor is detected by a change in current flowing through the motor, excluding a change in current that occurs when the motor is started. The fastening tool according to any one of claims 1 to 5, wherein the load applied to the motor is detected by a change in voltage applied to the motor, excluding a voltage change that occurs when the motor is started. The motor includes a first motor that rotates the bit holding portion;
a second motor that moves the bit holding portion along the axial direction,
The fastening tool according to any one of claims 1 to 7, wherein the control unit stops the rotation of the first motor and the second motor based on either or both of a load applied to the first motor that rotates the bit holding unit in one direction to fasten a screw, or a load applied to the second motor that rotates in one direction to move the bit holding unit toward an object to be fastened.