WO2020161881A1 - Lapping jig, lapping device, and lapping method - Google Patents

Abstract

Provided is a lapping technique with which it is possible to carry out lapping with a whole form processing tool through flexible adjustment of a retention orientation of a ball screw nut. This lapping jig is provided with: a jig base which is disposed in a fixed manner on a rotational center axis; and a tracing retention part which is mounted to the jig base and which holds a ball screw nut while changing the orientation of the ball screw nut with respect to the jig base by tracing, in an outer surface of a whole form processing tool, a processing region where the grinding of a thread groove takes place in sliding contact with the thread groove.

Description

Lapping jig, lapping device, and lapping method

The present invention relates to the holding of a ball screw nut when the thread groove of the ball screw nut is ground and lapped with a shaping tool.

Conventionally, there is a ball screw mechanism as one of the drive mechanisms equipped on industrial robots. The ball screw nut used in this ball screw mechanism has a spiral screw groove in which a ball rolls. The thread groove is formed into a predetermined shape by cutting and then finished to a final size by grinding with a shaping tool, so-called lapping.

This lapping process is performed using a lapping device as shown in Patent Document 1, for example. In the device described in Patent Document 1, the ball screw nut is held by chuck means (corresponding to the “lapping jig” of the present invention) having three chuck claws. Further, at the upper position of the chuck means, the lap bar having the shaft structure (corresponding to the “molding tool of the present invention”) is rotated with the axis of the lap bar aligned with the central axis of rotation extending in the vertical direction. While being reciprocally movable in the vertical direction. Then, the rotating lap bar is screwed into the ball screw nut held by the chuck means at a predetermined rotation speed and a predetermined feed rate, whereby lapping is performed.

JP-A-2002-292520 (FIG. 7)

As described above, in the lapping device of Patent Document 1, the ball screw nut is fixedly held by the chuck means, and the lap bar moves up and down along the rail extending in the vertical direction. That is, in the lapping apparatus, the lapping process is performed on the assumption that the axis of the ball screw nut held by the chuck means coincides with the axis (rotation center axis) of the lap bar. Therefore, for example, when at least one of the holding attitude of the ball screw nut by the chuck means and the installation attitude of the lap bar is improper, the axes of the two are misaligned and do not match, and lapping can be performed with sufficient machining accuracy. Have difficulty. In particular, when the ball screw nut is distorted due to the heat treatment performed between the cutting process and the grinding process, the holding posture of the ball screw nut by the chuck means becomes unsatisfactory, which cannot be dealt with by the conventional device.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a lapping technique that can flexibly adjust the holding posture of a ball screw nut to favorably perform lapping with a shaping tool.

A first aspect of the present invention holds a ball screw nut that is reciprocally moved in a first direction while rotating around a rotation center axis extending in a first direction, in which a thread groove is ground and lapped by a shaping tool. It is a lapping jig that is fixedly mounted on the rotation center axis, and is attached to the jig base and slidably contacts the thread groove on the outer surface of the forming tool to grind the thread groove. The present invention is characterized by including a copy holding portion that holds the ball screw nut while changing the posture of the ball screw nut with respect to the jig base in accordance with the processing area being processed.

A second aspect of the present invention is a lapping apparatus that grinds and laps a thread groove of a ball screw nut with a shaping tool having a shaft structure extending in a first direction, and is the lapping jig. , A tool driving unit that reciprocates the shaping tool in a first direction with respect to a ball screw nut held by a lapping jig while rotating the shaping tool about a rotation center axis extending in the first direction. It is characterized by that.

Furthermore, a third aspect of the present invention is a lapping method in which a thread groove of a ball screw nut is ground and lapped with a shaping tool having a shaft structure extending in a first direction, and the lapping jig is used. The first step of holding the ball screw nut and the ball screw nut held by the lapping jig in the first direction while rotating the forming tool in the first direction while rotating the forming tool around the rotation center axis extending in the first direction. And a second step of moving it back and forth.

According to the invention thus constituted, the ball screw nut is reciprocally moved in the first direction with respect to the ball screw nut while rotating the die processing tool around the rotation center axis extending in the first direction. The thread groove is ground and lapped. At the time of this lapping, the ball screw nut is held while changing the posture of the ball screw nut in accordance with the processing area in which the thread groove is ground by sliding contact with the thread groove on the outer surface of the shaping tool. .. Therefore, lapping is performed in a state where the axis of the shaping tool and the axis of the ball screw nut are aligned.

As described above, the lapping jig that holds the ball screw nut while changing the attitude of the ball screw nut according to the processing area where the thread groove is ground by sliding contact with the thread groove on the outer surface of the die-cutting tool. Lapping is done using a tool. Therefore, it is possible to flexibly adjust the holding posture of the ball screw nut and satisfactorily perform the lapping with the shaping tool.

It is a figure which shows 1st Embodiment of the lapping apparatus which concerns on this invention. It is a perspective view which shows the lapping jig used with the lapping apparatus shown in FIG. It is a block diagram which shows the electric constitution of the lapping apparatus shown in FIG. It is a figure which shows typically operation|movement of the lapping jig during lapping. It is a figure which shows the operation|movement of the lapping jig 2 before and after lapping typically. 3 is a flowchart showing a procedure of lapping by the lapping device shown in FIG. 1. It is a figure which shows typically the procedure of lapping by the lapping apparatus shown in FIG. It is a figure which shows typically the additional procedure of lapping by the lapping apparatus which concerns on 2nd Embodiment of this invention.

FIG. 1 is a diagram showing a first embodiment of a wrapping device according to the present invention. FIG. 2 is a perspective view showing a lapping jig used in the lapping device shown in FIG. Further, FIG. 3 is a block diagram showing an electrical configuration of the lapping device shown in FIG. The lapping apparatus 1 includes a machining tool 100 in a state in which an axial center AX1 of a general-purpose machining tool (hereinafter simply referred to as “machining tool”) 100 having a shaft structure extending in the vertical direction Z is aligned with a rotation center axis AR. The thread groove 201 of the ball screw nut 200 (hereinafter, simply referred to as "nut 200") held by the lapping jig 2 by reciprocating in the Z direction while rotating about the rotation center axis AR is ground by the processing tool 100. Then, lap finishing is performed. Note that, in FIGS. 1 and 2, XYZ rectangular coordinate axes are shown in order to clarify the directional relationship of each drawing. In these drawings, the vertical direction Z corresponds to an example of the "first direction" of the present invention, the arrow Z1 in the Z direction points in the outward direction of the machining tool 100, and the arrow Z2 in the Z direction indicates. The processing tool 100 faces the backward direction. XYZ rectangular coordinate axes are shown in FIGS. 1 and 2 by the vertical direction Z and the horizontal directions X and Y orthogonal to the Z direction. The Y direction corresponds to an example of the “second direction” of the present invention, the arrow Y1 in the Y direction faces the left side of the lapping device 1 when viewed from the front side, and the arrow Y2 in the Y direction indicates the lapping. It faces the right side of the device 1. Further, the X direction corresponds to an example of the “third direction” of the present invention, the arrow X1 in the X direction faces the front side of the lapping apparatus 1, and the arrow X2 in the X direction indicates the back side of the lapping apparatus 1. Looking to the side. Further, the arrow R in FIG. 1 indicates the rotation direction of the processing tool 100.

As shown in FIG. 1, the wrapping device 1 is erected on a base 3, a ball screw nut support device 4 mounted on the upper front side of the base 3, and an upper rear side of the base 3. An upper support base 5, an elevating head 7 supported by the upper support base 5 via an elevating device 6, and a rotation drive device 8 provided on the elevating head 7. Of these, the ball screw nut supporting device 4 is configured such that the table 42 is moved up and down in the vertical direction Z by operating the operating lever 41. The lapping jig 2 is fixed to the upper surface of the table 42, and the nut 200 can be detachably held by the lapping jig 2. The detailed structure and operation of the lapping jig 2 will be described later.

Above the lapping jig 2 that holds the nut 200, as shown in FIG. 1, an elevating head 7 is provided so as to be capable of reciprocating in the vertical direction Z, and is vertically moved by an elevating device 6. The lifting device 6 includes a pair of left and right slide rails 61, 61 attached to the front surface (X1 direction side) of the upper support 5 extending in the vertical direction Z as shown in FIG. 1 (only the Y2 direction side is shown in FIG. 1). A slider 62 supported by these slide rails 61 so as to be able to move up and down, a ball screw nut 63 attached to a central portion of the slider 62 in the left-right direction Y, and a vertical direction penetrating the ball screw nut 63. The ball screw shaft 64 extends in the direction Z, and the lifting motor 65 connected to the upper end of the ball screw shaft 64 and the like. Then, the lifting motor 65 is rotated forward in response to a command from the control device 9 that controls the entire lapping device 1, and the lifting head 7 configured as follows is moved in the outward direction (Z1 direction side). The reverse rotation makes it possible to move the elevating head 7 in the backward direction (Z2 direction side).

As shown in FIG. 1, the elevating head 7 includes a spindle housing 71 mounted on the front surface of a slider 62, and a cylindrical spindle 72 rotatably supported by a bearing (not shown) inside the spindle housing 71. , A tap chuck 73 attached to the spindle 72 and the like. Weight canceling weights 75 are connected to both ends of the spindle housing 71 through wires 74. The wire 74 is laid over pulleys 76, 76 provided on the upper end of the upper support 5 to connect the weight 75 housed in the upper support 5 and the spindle housing 71.

The upper end of the spindle 72 projects upward from the upper end of the spindle housing 71, and the lower end of the spindle 72 projects downward from the lower end of the spindle housing 71. A rotation driving device 8 for rotating the processing tool 100 is connected to the upper end of the spindle 72. The rotary drive device 8 includes a speed reducer 82 attached to a support plate 81 extending forward (X1 direction side) from an upper end of a spindle housing 71, and a rotary drive motor 83 mounted on the speed reducer 82. A belt type transmission device 84 for transmitting power from the speed reducer 82 to the upper end of the spindle 72. Therefore, it is possible to rotate the spindle 72 around the rotation center axis AR by operating the rotation driving motor 83 in response to a command from the control device 9.

At the lower end of the spindle 72, although not shown in FIG. 1, a tapered socket is formed so as to open downward, and a tapered shank of the tap chuck 73 is attached. Then, the upper end of the processing tool 100 is gripped by the tap chuck 73, and the processing tool 100 is mounted on the tap chuck 73 with the axis AX1 aligned with the rotation center axis AR. Then, according to a command from the control device 9, the rotation driving motor 83 operates to rotate the processing tool 100 around the rotation center axis AR, and the lifting motor 65 operates to move the processing tool 100 in the vertical direction. It reciprocates in Z, that is, moves in the Z axis. By rotating the machining tool 100 about the rotation center axis AR and reciprocating in the vertical direction Z in this manner, the abrasive grains adhered to the outer surface of the machining tool 100 by electrodeposition, adhesion or the like are screw grooves 201 of the nut 200. Grind. In this way, lapping of the nut 200 can be performed. While the lapping is being performed, the nut 200 follows the outer surface of the machining tool 100, and the axis AX2 (see FIGS. 2 and 6) of the nut 200 has the rotation center axis AR (machining), as will be described below. The posture of the nut 200 can be adjusted so as to coincide with the axis AX1) of the tool 100. On the other hand, before and after lapping, the nut 200 is held by the lapping jig 2 in a predetermined initial posture. The configuration and operation of the lapping jig 2 that holds the nut 200 in this way will be described with reference to FIGS. 2, 4A, and 4B.

4A and 4B are partial cross-sectional views of the lapping jig shown in FIG. 2, FIG. 4A schematically shows the operation of the lapping jig 2 during lapping, and FIG. 4B shows the lapping jig 2 before and after lapping. The operation of is schematically shown. As shown in FIGS. 2, 4A, and 4B, the lapping jig 2 includes a jig base 21 fixedly arranged on the upper surface of the table 42 on an extension line of the rotation center axis AR of the machining tool 100, and later. As will be described in detail, a copy holding portion 22 that holds the nut 200 while changing the posture of the nut 200 with respect to the jig base 21 according to the shape of the outer surface of the processing tool 100 is provided.

The jig base 21 is a frame body having a frame shape in a plan view from vertically above (Z2 direction side), and the nut 200 is held by the nut holding member 23 in the central space thereof. In the present embodiment, the nut holding member 23 has a jig base 231 and a support frame 232, and the jig base 231 holding the nut 200 is supported by the support frame 232 while being surrounded from the horizontal direction. There is. Then, in order to displace the nut holding member 23 and adjust the posture of the nut 200, the copying holding portion 22 is configured as follows, and a tilt adjusting function for adjusting the tilt posture of the nut 200 with respect to the rotation center axis AR. And a horizontal adjustment function of adjusting the horizontal position of the nut 200 with respect to the rotation center axis AR.

The copy holding unit 22 has a gimbal mechanism 24 including a movable frame 240, a first swing support shaft 241, and a second swing support shaft 242. More specifically, the movable frame 240 is a frame body having a frame shape like the jig base 21, and is arranged so as to surround the nut holding member 23 in the central space of the jig base 21 from the horizontal direction. First swing support shafts 241 are provided between the movable frame 240 and the jig base 21 at two positions separated in the Y direction. As shown in FIGS. 4A and 4B, each of these two rocking support shafts 241 has an inner bush 241a, a slide shaft 241b, and a connecting pin 241c, and the nut 200 held by the nut holding member 23 They are arranged symmetrically across. Therefore, the configuration of the first swing support shaft 241 on the Y2 direction side will be described here, and the description on the Y1 direction side will be omitted.

On the side wall of the jig base 21 on the Y2 direction side, a through hole is provided in the Y direction at a substantially central position in the X direction, and a cylindrical inner bush 241a is inserted in the Y direction in the through hole. A slide shaft 241b is slidably inserted into the hollow portion of the inner bush 241a in the Y direction with respect to the inner bush 241a. A through hole is formed in the slide shaft 241b in the Y direction. The connecting pin 241c is inserted into the through hole from the Y2 direction side toward the Y1 direction side, and the tip end thereof is connected to the side wall of the movable frame 240 on the Y2 direction side. The first swing support shaft 241 is provided on the Y1 direction side as well as on the Y2 direction side. Therefore, the movable frame 240 is allowed to swing around the Y direction with respect to the jig base 21 by these two first swing support shafts 241, and the movable frame 240, the slide shaft 241b, and the connecting pin 241c are integrated. It is slidable in the Y direction.

Further, the second swing support shaft 242 is provided between the movable frame 240 and the nut holding member 23 at two positions separated in the X direction. As shown in FIGS. 4A and 4B, each of these two swing support shafts 242 has an inner bush 242a, a slide shaft 242b, and a connecting pin 242c, and the nut 200 held by the nut holding member 23 They are arranged symmetrically across. Therefore, here, the configuration of the second swing support shaft 242 on the X2 direction side will be described, and the description on the X1 direction side will be omitted.

On the side wall of the movable frame 240 on the X2 direction side, a through hole is provided in the X direction at a substantially central position in the Y direction, and a cylindrical inner bush 242a is inserted in the X direction in the through hole. A slide shaft 242b is slidably inserted in the hollow portion of the inner bush 242a in the X direction with respect to the inner bush 242a. A through hole is formed in the slide shaft 242b in the X direction. The connecting pin 242c is inserted into the through hole from the X2 direction side toward the X1 direction side, and the tip portion thereof is on the X2 direction side of the support frame 232. Is connected to the side wall. A second swing support shaft 242 is provided on the X1 direction side as well as on the X2 direction side. Therefore, the two second swing support shafts 242 allow the support frame 232 to swing about the movable frame 240 around the X direction, and the support frame 232, the slide shaft 242b, and the connecting pin 242c are integrally formed. It is slidable in the X direction.

As described above, in the present embodiment, by providing the gimbal mechanism 24, it is possible to tilt the nut holding member 23 with respect to the rotation center axis AR and change the tilted posture of the nut 200. Further, the first swing support shaft 241 and the second swing support shaft 242 have a slide bearing structure in the Y direction and the X direction, respectively, and function as the "moving mechanism" of the present invention, and the nut holding member 23 is moved in the Y direction. And can be moved in the X direction. That is, the horizontal position of the nut 200 with respect to the rotation center axis AR can be changed by the moving mechanism. Therefore, as shown in FIG. 4A, when the movable frame 240 and the support frame 232 can be freely displaced, the outer surface of the machining tool 100 is brought into sliding contact with the thread groove 201 of the nut 200 to perform lapping, and grinding is performed. When the process is executed, the nut 200 tilts or horizontally moves along the outer surface of the processing tool 100. Therefore, as shown in FIG. 6 described later, the posture of the nut 200 can be adjusted so that the axis AX2 of the nut 200 matches the rotation center axis AR (axis AX1 of the machining tool 100). In the present specification, a mode in which the posture of the nut 200 can be changed by following the machining tool 100 in this manner is referred to as a “copy setting mode”.

Here, if you consider only lapping, it is possible to set the lapping jig 2 to the copy setting mode at all times. However, workability when the nut 200 is mounted on the lapping jig 2 is secured, a phase is secured when the processing tool 100 is inserted into the thread groove 201 of the nut 200 to execute the lapping, and the nut 200 is removed after the lapping is completed. In consideration of workability at the time, it is desirable to position the nut 200 at an initial position suitable for securing a phase before and after lapping and to restrict the displacement of the nut 200 from the initial position. Therefore, in the present embodiment, in addition to the above-mentioned copying setting mode, an "initial setting mode" for positioning the nut 200 at the initial position and restricting the displacement from the initial position is provided, and a mode switching mechanism 25 for switching these is provided. ing.

The mode switching mechanism 25 has an air cylinder 251 that positions and fixes the nut 200 at the initial position in the X direction, and an air cylinder 252 that positions and fixes the nut 200 at the initial position in the Y direction. Corresponding to the piston portion 251p of the air cylinder 251, the through holes 211, 2401 and the recessed portion 2321 are provided on the Y1 direction side wall portions of the jig base 21, the movable frame 240 and the support frame 232, respectively, and the nut 200 is at the initial position. When positioned, they line up in the Y direction. Therefore, even if the movable frame 240 and the support frame 232 are displaced in the X direction with respect to the jig base 21 following the machining tool 100, the piston portion 251p of the air cylinder 251 is operated in response to a command from the control device 9. The movable frame 240 and the support frame 232 are returned to their initial positions in the X direction by extending in the Y2 direction. That is, when the piston portion 251p enters the through holes 211, 2401 and the recess 2321, the jig base 21, the movable frame 240 and the support frame 232 are skewered in the Y direction by the piston portion 251p, and in the process, the state shown in FIG. 4A. To the state shown in FIG. 4B, the nut 200 is positioned at the initial position in the X direction.

Also, positioning in the Y direction is the same as in the X direction. That is, corresponding to the piston portion 252p of the air cylinder 252, the through hole 212 and the recessed portion 2402 are provided on the wall portion of the jig base 21 and the movable frame 240 on the X2 direction side, respectively, and when the nut 200 is located at the initial position. Are aligned linearly in the X direction. Therefore, even if the movable frame 240 and the support frame 232 are displaced in the Y direction with respect to the jig base 21 following the machining tool 100, the piston portion 252p of the air cylinder 252 is moved in response to a command from the control device 9. By extending in the X1 direction side, the movable frame 240 and the support frame 232 are returned to the initial position in the Y direction. That is, the jig base 21 and the movable frame 240 are skewered in the X direction by the piston portion 252p due to the piston portion 252p entering the through hole 212 and the concave portion 2402, and in the process, the state shown in FIG. 4A to the state shown in FIG. 4B. Then, the nut 200 is positioned at the initial position in the Y direction.

By the extension operation of the air cylinders 251 and 252 in this way, as shown in FIG. 4B, the piston portions 251p and 252p enter and the nut holding member 23 is positioned at the initial position in the horizontal direction. As a result, in design, the axis of the nut 200 held by the nut holding member 23 (reference numeral AX2 in FIGS. 2 and 6) coincides with the rotation center axis AR of the machining tool 100 within a certain range. Simultaneously with such positioning operation, horizontal movement and inclination of the nut 200 with respect to the rotation center axis AR are restricted at that position, that is, the gimbal mechanism 24 is locked (initial setting mode).

On the contrary, the contraction operation of the air cylinders 251 and 252 causes the piston portions 251p and 252p to retract into the through holes 211 and 212 of the jig base 21, respectively, as shown in FIG. 4A, and the gimbal mechanism 24 is unlocked. It When the machining tool 100 is inserted into the thread groove 201 of the nut 200 to reciprocate in order to perform lapping in this state, the nut 200 moves horizontally with respect to the rotation center axis AR and tilts along the machining tool 100. Then, the outer surface of the machining tool 100 appropriately slides in contact with the thread groove 201 in a state where the axis AX2 of the nut 200 matches the rotation center axis AR (axis AX1 of the machining tool 100) (copy setting mode). Then, the thread groove 201 is satisfactorily ground by the abrasive grains attached to the outer surface of the processing tool 100 as the processing tool 100 reciprocates.

A control device 9 is provided to control the lapping device 1 configured as described above. The control device 9 includes an arithmetic processing unit 91 configured by a CPU (Central Processing Unit). A storage unit 92, a motor control unit 93, a cylinder control unit 94, an external input/output unit 95, a display unit 96, and an input unit 97 are connected to the arithmetic processing unit 91, respectively. Then, the arithmetic processing section 91 controls each part of the apparatus according to a program stored in advance in the storage section 92 to execute the lapping.

The motor control unit 93 drives a lifting motor (Z-axis motor) 65 to move the machining tool 100 up and down, and drives a rotation driving motor (R-axis motor) 83 to rotate the machining tool 100 around the rotation center axis AR. Rotate to. Further, the motor control unit 93 provides the arithmetic processing unit 91 with the current value when driving and controlling the motors 65 and 83 as information relating to the motor torque. Therefore, the arithmetic processing unit 91 can detect with high accuracy whether or not the rotation of the processing tool 100 is abnormal based on the information.

The cylinder control section 94 expands and contracts the piston sections 251p and 252p by controlling the compressed air given to the air cylinders 251 and 252, and switches the mode between the initial setting mode and the copy setting mode.

The external input/output unit 95 is a so-called interface and is configured to receive detection signals output from various sensors 951 provided in the lapping apparatus 1. These detection signals include a signal from the proximity sensor 951a that detects the position of the tap chuck 73, and the arithmetic processing unit 91 can detect the presence or absence of a floating abnormality in the tap chuck 73 based on the signal. Has become.

The display unit 96 is composed of a liquid crystal display device or the like having a display screen, and displays the state of the wrapping device 1 on the display screen. The input unit 97 is composed of a keyboard and the like, and is adapted to receive an external input by a manual operation of an operator.

In the lapping apparatus 1 configured as described above, the program stored in the storage unit 92 is read out to the arithmetic processing unit 91, and the arithmetic processing unit 91 controls each unit of the device as follows to finish the lapping of the nut 200. Is executed. Hereinafter, lapping by the lapping apparatus 1 will be described with reference to FIGS. 4A, 4B, 5 and 6.

FIG. 5 is a flowchart showing a procedure of lapping by the lapping device shown in FIG. Further, FIG. 6 is a diagram schematically showing a procedure of lapping by the lapping device shown in FIG. White arrows in columns (a), (b), and (d) of the figure show a state in which the gimbal mechanism 24 is locked by the extension operation of the air cylinders 251 and 252. The broken line in the column (c) indicates a state in which the gimbal mechanism 24 is unlocked by the contraction operation of the air cylinders 251 and 252, and the horizontal movement operation and tilting operation of the nut 200 with respect to the rotation center axis AR are free. ing.

The operator sets the nut 200 on the lapping jig 2 with the one end surface 202 of the nut 200 before lapping facing the processing tool 100 (corresponding to an example of the "first step" of the present invention). At this time, each part of the lapping apparatus 1 is located at the origin position. That is, as shown in FIG. 1, the processing tool 100 attached to the elevating head 7 is positioned vertically above the lapping jig 2, that is, at the origin position P1 (FIG. 6) apart from the lapping jig 2 in the Z2 direction while the rotation is stopped. ing. In the lapping jig 2, the air cylinders 251 and 252 extend (FIG. 4B) and lock the gimbal mechanism 24. This prevents horizontal movement and inclination of the nut holding member 23 with respect to the rotation center axis AR, and facilitates mounting of the nut 200 on the nut holding member 23 by an operator.

When the setting of the nut 200 on the lapping jig 2 is completed, the operator gives a command to start lapping to the control device 9 via the input unit 97. In response to this, the arithmetic processing unit 91 of the control device 9 controls each part of the device as follows to perform lapping of the nut 200. First, the elevating motor (Z-axis motor) 65 is operated to lower the machining tool 100 from the origin position P1 to the position P2 immediately above the nut 200 as shown in the column (a) of FIG. 6 (step S1). The descent of the processing tool 100 is executed at a relatively high speed, while the rotation of the processing tool 100 is stopped.

When the descent to the position P2 immediately above is completed, the lifting motor 65 slows down the rotation speed and switches the descent speed of the processing tool 100 to a low speed. Further, the rotation driving motor (R-axis motor) 83 operates in synchronization with the low speed descent to start the normal rotation of the processing tool 100 (step S2). Here, "normal rotation" means a direction in which the thread groove 201 is ground and lapped by the abrasive grains attached to the outer surface of the processing tool 100 while the processing tool 100 is being lowered, and is opposite to "normal rotation". The “reverse rotation” means a direction in which the thread groove 201 is ground and lapped by the abrasive grains attached to the outer surface of the processing tool 100 while the processing tool 100 is raised.

In this way, when the machining tool 100 is lowered while being rotated in the forward direction, as shown in the column (b) of FIG. 6, the tip of the machining tool 100 slides on the Z2 direction side end of the nut 200 to form the thread groove 201. And the phase matches, and it enters. At this time, when the axial center AX1 of the machining tool 100 and the axial center AX2 of the nut 200 are largely deviated from each other or when the tip of the machining tool 100 is out of phase with the thread groove 201, the machining tool 100 is On the other hand, a problem that a large torque is applied in the rotation direction (R-axis direction) (R-axis torque abnormality) and a problem that the tap chuck 73 connected to the processing tool 100 expands and contracts more than expected (floating abnormality) occur. To do. If the operation is executed with these problems occurring, defective lapping, shortening of the life of the processing tool 100, device failure, etc. are caused. Therefore, in the present embodiment, as shown in the column (b) of FIG. 6, the processing tool 100 descends to a preset initial insertion position P3 and the initial insertion amount (for example, about 1/3 of the nut 200 is inserted). The current value of the lifting motor 65 is monitored to monitor the R-axis torque abnormality and the proximity sensor 951a monitors the floating abnormality until the nut 200 is inserted into the nut 200 (step S3, S4). .. Here, in order to detect the R-axis torque abnormality, the torque applied to the processing tool 100 may be directly measured by the torque sensor. Further, the sensor for detecting the floating abnormality is not limited to the proximity sensor 951a, and any position detection sensor can be used.

When at least one of the R-axis torque abnormality and the floating abnormality is detected in step S3, the control device 9 stops the lifting motor 65 and the rotation driving motor 83 and stops the device due to the occurrence of an abnormality on the display unit 96. Notify (step S5). The operator who confirms this alarm notification operates the lifting motor 65, the rotation driving motor 83, and the like through the input unit 97 to return the processing tool 100 to the origin position P1 while trying to eliminate the above-mentioned abnormality, and thereby the respective parts of the apparatus are changed. Return to origin. When the abnormality is eliminated and the preparation for the retry of lapping is completed, the operator operates the input unit 97 to give a restart command to the control device 9. When this restart command is received ("YES" in step S6), the controller 9 returns to step S1 and retries the lap finishing.

On the other hand, when the initial insertion of the machining tool 100 is completed without causing the R-axis torque abnormality and the floating abnormality (“YES” in step S4), the air cylinders 251 and 252 contract (FIG. 4A), and the gimbal mechanism. The lock of 24 is released (step S7). At this time, when the axial center AX2 of the nut 200 held by the nut holding member 23 matches the rotation center axis AR of the processing tool 100, the nut holding member 23 does not move and its position is maintained. .. On the other hand, when they do not coincide with each other, the nut holding member 23 horizontally moves and/or inclines with respect to the rotation center axis AR following the outer surface of the machining tool 100, and as a result, is held by the nut holding member 23. The axis AX2 of the rotating nut 200 coincides with the rotation center axis AR of the machining tool 100.

After unlocking the gimbal mechanism 24, rotation of the machining tool 100 and reciprocating movement in the Z direction (hereinafter referred to as "rotation reciprocating movement of machining tool 100") are started at a rotation speed and a movement speed suitable for lapping (step). S8). That is, the processing tool 100 is rotated in the normal rotation and lowered in the Z1 direction at a speed suitable for lapping, so that the central region 101 (column (c) in FIG. 6) of the outer surface of the processing tool 100 in the Z direction. ) Is in sliding contact with the thread groove 201 as the “processing area” of the present invention, and the thread groove 201 is ground by the abrasive grains attached to the central area 101. On the contrary, the machining tool 100 is rotated in the reverse direction and moves upward in the Z2 direction, so that the central region 101 is brought into sliding contact with the thread groove 201, and the thread groove 201 is ground by the abrasive grains attached to the central area 101. .. When the working tool 100 that rotates in the forward and reverse directions reciprocates in this way, the thread groove 201 of the nut 200 follows the outer surface of the working tool 100, and horizontal movement and tilting with respect to the rotation center axis AR are appropriately performed to allow the nut 200 to rotate. Lapping is performed in a state where the center AX2 coincides with the rotation center axis AR of the processing tool 100 (corresponding to an example of the "second step" of the present invention).

　There is a possibility that R-axis torque abnormality will occur while lapping is performed in this way. Therefore, in the present embodiment, the arithmetic processing unit 91 monitors the occurrence of the R-axis torque abnormality based on the current value of the lifting motor 65 while the number of times of the reciprocating rotation is repeated by the value pointed out by the operator in advance. (Steps S9 and S10). Then, when the R-axis torque abnormality occurs (“YES” in step S9), the arithmetic processing unit 91 temporarily stops the driving of the lifting motor 65 and the rotation driving motor 83 to rotate the machining tool 100 back and forth. Is interrupted, and then the reverse driving is performed at a low speed by a constant amount. For example, if an R-axis torque abnormality occurs while the machining tool 100 is being rotated in the normal direction and is being lowered in the Z1 direction, the machining tool 100 is rotated in the reverse direction by a certain amount and raised in the Z2 direction. On the other hand, if the R-axis torque abnormality occurs while the machining tool 100 is being rotated in the reverse direction and being raised in the Z2 direction, the machining tool 100 is rotated in the normal direction by a certain amount and lowered in the Z1 direction. After that, the process returns to step S8, and the reciprocating rotation of the processing tool 100 is restarted.

When the number of rotational reciprocating movements of the processing tool 100 reaches the indicated value and the lapping of the nut 200 is completed (“YES” in step S10), the processing tool 100 is rotated in the reverse direction while being raised in the Z2 direction, and the origin is obtained. After returning to the position P1 (step S12), the rotation and movement of the processing tool 100 are stopped. In the lapping jig 2, the air cylinders 251 and 252 extend (FIG. 4B) and lock the gimbal mechanism 24. In this way, a series of processes for one nut 200 is completed.

As described above, in the present embodiment, the center of rotation of the nut holding member 23 follows the central region 101 (corresponding to the “machining region” of the present invention) in which the thread groove 201 is ground on the outer surface of the machining tool 100. It is horizontally moved and tilted with respect to the axis AR. Accordingly, during lapping, the posture of the nut 200 is adjusted such that the axis AX2 of the nut 200 matches the rotation center axis AR of the processing tool 100. Therefore, the thread groove 201 can be ground in a state where the axis of the machining tool 100 and the axis of the nut 200 are aligned, and the lapping of the nut 200 by the machining tool 100 can be performed with high accuracy.

Moreover, since the lapping is performed in a state where the axis AX1 of the machining tool 100 and the axis AX2 of the nut 200 are aligned, an extra external force, for example, bending stress acts on the machining tool 100 during lapping. Can be prevented, and the life of the processing tool 100 can be extended.

Also, when the nut 200 is set on the lapping jig 2, the mode switching mechanism 25 switches to the initial setting mode. That is, the gimbal mechanism 24 is locked and the nut 200 held by the nut holding member 23 is positioned at the initial position. In this state, the nut 200 can be stably set on the lapping jig 2.

Further, it is necessary to insert the tip of the processing tool 100 into the nut 200 while matching the phase with the thread groove 201 before performing lapping by the rotational reciprocating movement of the processing tool 100, but in the present embodiment, the initial setting mode is maintained. The initial insertion described above is performed as it is. Therefore, it is possible to stably perform the initial insertion while restricting the displacement of the nut 200.

Furthermore, after finishing the lapping, the mode switching mechanism 25 returns the copying setting mode to the initial setting mode. Therefore, the lapped nut 200 can be stably removed from the lapping jig 2.

In the above-described embodiment, the rotation center axis AR corresponds to an example of "the rotation center axis extending in the first direction" of the present invention. Further, the combination of the lifting device 6 and the rotation drive device 8 functions as the "tool drive unit" of the present invention. Further, the end surface 202 of the nut 200 on the Z2 direction side corresponds to an example of the "one end surface of the ball screw nut" of the present invention, and the end surface 203 of the nut 200 on the Z1 direction side of the "other end surface of the ball screw nut" of the present invention. Corresponds to an example.

Note that the present invention is not limited to the above embodiment, and various modifications can be made to the above without departing from the spirit of the present invention. For example, in the above-described embodiment, the rotary reciprocating movement is performed the specified number of times, for example, 2N times, to perform the lapping only when the one end surface 202 of the nut 200 faces the processing tool 100. However, similar to the first embodiment. After performing the lapping, the lapping jig 2 may be turned upside down, and the lapping may be performed with the other end surface 203 of the nut 200 facing the processing tool 100 as shown in FIG. 7 (second embodiment). form). By thus performing the lapping in two different modes, the finishing accuracy can be further improved. Further, regarding the number of times of reciprocating rotation in the second embodiment, N times are performed with the one end surface 202 of the nut 200 facing the processing tool 100 and N times with the other end surface 203 of the nut 200 facing the processing tool 100. It may be configured to be performed once.

Further, in the above-described embodiment, in addition to the tilting function in which the copy holding portion 22 tilts the nut holding member 23 with respect to the rotation center axis AR to change the tilted posture of the nut 200, the nut holding member 23 is moved in the Y direction and the X direction. A moving function is added to change the horizontal posture of the nut 200 by horizontally moving the nut 200 to the rotation center axis AR. As a modified example, only a moving mechanism that shifts the nut holding member 23 in the X direction may be added, or conversely, only a moving mechanism that shifts the nut holding member 23 in the Y direction may be added.

In addition, the copy holding unit 22 is configured to have only a moving function of moving the nut holding member 23 in the Y direction and the X direction and horizontally shifting the nut holding member 23 with respect to the rotation center axis AR to change the horizontal posture of the nut 200. Good.

Further, in the above embodiment, the Z direction, the Y direction and the X direction which are orthogonal to each other are set as the “first direction”, the “second direction” and the “third direction” of the present invention. The direction may be set as the “first direction” of the present invention, and the remaining two directions may be set as the “second direction” and the “third direction”, respectively. Further, it is not essential that the “first direction”, the “second direction” and the “third direction” of the present invention are orthogonal to each other, and they may be set to intersect with each other.

The present invention can be applied to all lapping techniques for grinding and lapping the thread groove of a ball screw nut with a shaping tool.

1... Lapping device 2... Lapping jig 6... Lifting device (tool drive unit)
8... Rotation drive device (tool drive unit)
21... Jig base 22... Copy holding part 23... Nut holding member 24... Gimbal mechanism 25... Mode switching mechanism 100... (Form) Processing tool 101... Central area (processing area)
200... (Ball screw) Nut 201... Thread groove 202... (One side) End surface 203... (Other side) End surface 240... Movable frame 241... First swing support shaft 242... Second swing support shaft AR... Rotation center axis AX1... Shaft center (of processing tool) AX2... (Shaft center of ball screw nut) X... Horizontal direction (third direction)
Y: Left-right direction (second direction)
Z: vertical direction (first direction)

Claims (11)

A lapping jig for holding a ball screw nut, which is reciprocally moved in the first direction while rotating around a rotation center axis extending in the first direction and whose thread groove is ground and lapped by a shaping tool. ,
A jig base fixedly arranged on the rotation center axis,
The posture of the ball screw nut with respect to the jig base, which is attached to the jig base and follows the processing area in which the thread groove is ground by slidingly contacting the thread groove on the outer surface of the shaping tool. A lapping jig for holding the ball screw nut while changing the value. The lapping jig according to claim 1,
The copy holding portion holds a nut holding member for holding the ball screw nut, and the nut holding member around a second direction intersecting the first direction and around a third direction intersecting the first direction and the second direction. And a gimbal mechanism that swings a member to change the inclination of the ball screw nut with respect to the rotation center axis. The lapping jig according to claim 2,
The gimbal mechanism is
Movable frame,
A first unit provided at two locations separated from each other in the second direction between the jig base and the movable frame to support the movable frame with respect to the jig base so as to be swingable around the second direction. Swing support shaft,
A second portion provided between the movable frame and the nut holding member so as to be separated from each other in the third direction so as to support the nut holding member with respect to the movable frame so as to be swingable around the third direction. A lapping jig having a swing support shaft. The lapping jig according to claim 3,
A lapping jig in which the first swing support shaft is slidably provided in the second direction with respect to the jig base integrally with the movable frame. The lapping jig according to claim 3 or 4, wherein
A lapping jig in which the second swing support shaft is provided slidably in the third direction with respect to the movable frame integrally with the nut holding member. The lapping jig according to claim 1,
The copy holding portion holds the nut holding member holding the ball screw nut, and the nut holding member in a second direction intersecting the first direction and a third direction intersecting the first direction and the second direction. A lapping jig having a moving mechanism that moves and shifts the position of the ball screw nut in a plane including the second direction and the third direction. The lapping jig according to any one of claims 2 to 6,
The second direction is a direction orthogonal to the first direction,
A lapping jig in which the third direction is a direction orthogonal to the first direction and the second direction. The lapping jig according to any one of claims 1 to 7,
An initial setting mode in which the displacement of the ball screw nut is regulated while the ball screw nut held by the copy holding portion is positioned at a preset initial position with respect to the jig base; and the displacement of the ball screw nut. The lapping jig further includes a mode switching mechanism for switching between the copy setting mode for releasing the regulation of No. 1 and allowing the change of the posture of the ball screw nut. A lapping device for grinding and lapping a thread groove of a ball screw nut with a shaping tool having a shaft structure extending in a first direction,
A lapping jig according to any one of claims 1 to 8,
A tool that reciprocates the shaping tool in the first direction with respect to the ball screw nut held by the lapping jig while rotating the shaping tool about a rotation center axis extending in the first direction. A lapping device comprising: a drive unit. A lapping method for grinding and lapping a thread groove of a ball screw nut with a shaping tool having a shaft structure extending in a first direction,
A first step of holding the ball screw nut by the lapping jig according to any one of claims 1 to 8;
Reciprocating the shaping tool in the first direction with respect to the ball screw nut held by the lapping jig while rotating the shaping tool about a rotation center axis extending in the first direction; A lapping method comprising two steps. The wrapping method according to claim 10, wherein
The first step is a step of holding the ball screw nut in a state where one end surface of the ball screw nut in the first direction faces the shaping tool.
The second step is
A step of reciprocating the shaping tool with one end face of the ball screw nut facing the shaping tool;
Inverting the lapping jig to position the lapping jig such that the other end surface of the ball screw nut in the first direction faces the shaping tool.
Lapping method, in which the other end surface of the ball screw nut is moved back and forth with the other end surface facing the forming tool.

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