JP2008260110A - Work gripping device and work gripping method - Google Patents

Abstract

Provided is a workpiece gripping device that can grip a workpiece having different characteristics without exchanging a hand, and can grip a workpiece even when a gap between the workpiece and a surrounding object is narrow, and further, a workpiece supply posture is not limited.
A robot grips a workpiece with a hand. The hand includes a hand main body, four finger portions, and a finger portion adjusting mechanism that is provided on the hand main body and changes the relative posture and interval between the four finger portions. Each finger part is provided with the 4th table 21 supported by the finger part adjustment mechanism, and the rod-like finger 22 provided in this 4th table so that advancement / retraction was possible.
[Selection] Figure 4

Description

  The present invention relates to a workpiece gripping apparatus and a workpiece gripping method. Specifically, the present invention relates to a workpiece gripping apparatus and a workpiece gripping method for gripping a workpiece.

  Conventionally, an automobile is manufactured by combining a large number of parts. Specifically, for example, a plurality of robots are arranged on the production line, the work is transported along the production line, and parts to be attached to the work are accommodated in a box-shaped bucket, and the bucket is supplied to each robot. To do. Each robot grips a part in the bucket and attaches it to a workpiece to be transported on the production line.

  By the way, in order to operate the production line efficiently, a plurality of vehicle types are produced on one production line. On the other hand, there are many cases where characteristics such as the shape and the position of the center of gravity are greatly different depending on the type of vehicle even if the parts have the same function. Therefore, by preparing a hand with the optimal structure for each part, and selecting and mounting the optimal hand according to the characteristics of the part to be installed, a part with different characteristics can be obtained with one robot. Holding.

In addition, as a shape of the hand, a configuration has been proposed in which a finger of the hand is formed in a substantially square shape, and the workpiece is held so as to hold the workpiece with the substantially square-shaped finger (see Patent Document 1).
JP 2006-7337 A

  However, in the conventional method, since hands are frequently exchanged, there is a problem in that work efficiency is lowered and cycle time is prolonged, resulting in an increase in manufacturing cost. Therefore, there is a demand for the development of a workpiece gripping device that can grip a workpiece having a different shape and center of gravity without changing the hand.

  The hand holds the workpiece in the bucket. The conventional hand is designed according to the characteristics such as the shape of the part and the position of the center of gravity, and the posture of the workpiece in the gripped state is determined in advance. As a result, there is a problem that it is necessary to place the work in the bucket at a predetermined position in a predetermined posture, and management of the manufacturing process becomes complicated. Therefore, the development of a workpiece gripping device that does not limit the supply posture has been demanded.

  Furthermore, in the structure of the hand shown in Patent Document 1, when the gap between the workpiece and the bucket wall surface or the partition is small, there is a problem that the finger interferes with the bucket wall surface or the partition.

  The present invention can grip a workpiece having different characteristics without exchanging the hand, and can grip even when a gap between the workpiece and a surrounding object is narrow, and further, a workpiece gripping apparatus and a workpiece gripping device in which the supply posture of the workpiece is not limited It aims to provide a method.

  A workpiece gripping apparatus (for example, a robot 1 described later) according to the present invention is a workpiece gripping apparatus that grips a workpiece (for example, a mirror 60 and a sash 70 described later) with a hand (for example, a hand 11 described later), Are a hand main body (for example, a hand main body 14 to be described later), a plurality of finger portions (for example, a finger portion 20 to be described later), and a relative posture and interval between the plurality of finger portions provided on the hand main body. Finger part adjusting means (for example, a finger part adjusting mechanism 30 described later), and the plurality of finger parts are each supported by the finger part adjusting means (for example, a fourth table described later). 21) and a rod-like finger (for example, a finger 22 described later) provided on the table so as to be able to advance and retreat.

  According to the present invention, by gripping a work using a bar-like finger like a chopstick, even a work having a different shape and center of gravity can be gripped stably. Accordingly, since a single workpiece gripping device can grip and work on different workpieces without exchanging hands, the equipment for transporting workpieces can be simplified in configuration and manufacturing costs can be reduced.

  Because the fingers can be gripped close to the workpiece on the tip side of the fingers, when gripping or releasing the workpiece, even if there is a bucket wall or partition, the finger is unlikely to interfere with the surrounding walls or partition of the workpiece , Work efficiently.

  Further, since the workpiece is gripped in the most stable state, the posture of the workpiece in the gripped state is not limited, so the posture of supplying the workpiece is not limited. Therefore, it is not necessary to be very nervous about the positioning accuracy of the workpiece supply.

  In this case, the apparatus further includes a finger unit adjusting unit and a control unit (for example, a control device 13 to be described later) for controlling the fingers, and the control unit is configured to relatively move the plurality of tables according to the shape of the workpiece. It is preferred to optimize the attitude and spacing, and the protruding dimensions of the fingers from the table.

  According to the present invention, the relative posture and interval between the plurality of tables and the protruding dimensions of the fingers from the table are optimized according to the shape of the workpiece, so that the workpiece can be stably held.

  The work gripping method of the present invention is a work gripping method of gripping a work with a hand, wherein the hand is provided with a plurality of finger portions, and each finger portion is further provided with a table and a bar-like finger, and the finger portions While changing the relative attitude | position and space | interval of these tables, it hold | grips a workpiece | work by moving the said finger forwards or backwards from the said table, It is characterized by the above-mentioned.

  According to the present invention, there are effects similar to those described above.

  According to the present invention, by gripping a workpiece using a bar-like finger like a chopstick, it is possible to stably grip a workpiece having a different shape and center of gravity. Accordingly, since a single workpiece gripping device can grip and work on different workpieces without exchanging hands, the equipment for transporting workpieces can be simplified in configuration and manufacturing costs can be reduced. Since the finger can approach and grip the workpiece on the tip side of the finger, when gripping or releasing the workpiece, even if there is a wall or partition of the bucket, the finger is less likely to interfere with objects around the workpiece, making it efficient Can work well. Further, since the workpiece is gripped in the most stable state, the posture of the workpiece in the gripped state is not limited, so the posture of supplying the workpiece is not limited. Therefore, it is not necessary to be very nervous about the positioning accuracy of the workpiece supply.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a robot 1 as a workpiece gripping device of the present invention.

  The robot 1 grips a workpiece accommodated in a bucket and attaches the gripped workpiece to another workpiece conveyed on the production line. The robot 1 controls a base 10 provided on a floor surface, a hand 11 for gripping a workpiece, an arm 12 for changing the posture of the hand 11 and a position in a three-dimensional space, and the hand 11 and the arm 12. And a control device 13 as a control means.

FIG. 2 is a perspective view showing the configuration of the hand 11.
The hand includes a hand main body 14, four finger portions 20, and a finger portion adjusting mechanism 30 as finger portion adjusting means provided on the hand main body 14 to change the relative posture and interval between the four finger portions 20. .

The finger part adjusting mechanism 30 includes a pair of multi-joint arms 31 provided on the lower surface of the hand main body 14, a pair of multi-joint arms 32, and the pair of multi-joint arms 32 moving forward and backward toward the pair of multi-joint arms 31. A pair of slide mechanisms 33 to be moved.
Here, the direction perpendicular to the lower surface of the hand body 14 is taken as the Z axis, the direction in which the pair of articulated arms 31 are arranged is taken as the X axis direction, and the moving direction of the articulated arm 32 is taken as the Y axis.

FIG. 3 is a partially enlarged perspective view of the hand 11.
Each of the slide mechanisms 33 includes a motor 331 provided in the hand main body 14 and a feed screw mechanism 332 connected to the motor 331 and screwed into a first table 41 (to be described later) of the articulated arm 32.

The hand main body 14 is provided with a slide rail (not shown), and the first table 41 of the multi-joint arm 32 is provided with a slide guide 333 fitted to the slide rail.
According to the slide mechanism 33, the articulated arm 32 can be advanced and retracted with respect to the articulated arm 31 through the feed screw mechanism 332 by driving the motor 331.

Hereinafter, although the multi-joint arm 32 will be described, the multi-joint arm 31 has the same configuration as the multi-joint arm 32.
The articulated arm 32 includes a first table 41, a second table 42 that can rotate with respect to the first table 41, and a third table 43 that can rotate with respect to the second table.

The second table 42 can be rotated about the Z-axis direction as a rotation axis by the first rotation mechanism 44.
The first rotation mechanism 44 is fixed to the second table 42 and a motor 441 provided on the first table 41 and having the Z-axis direction as a rotation axis, a spur gear 442 attached to the rotation shaft of the motor 441, and the second table 42. A spur gear 443 that meshes with the spur gear 442.

The first table 41 is provided with a bearing portion 444 that rotatably holds the shaft portion of the spur gear 443.
According to the first rotation mechanism 44, the second table 42 can be rotated with respect to the first table 41 via the spur gear 442 and the spur gear 443 by driving the motor 441.

The third table 43 has a long shape extending in the Z-axis direction, and can be rotated by the second rotation mechanism 45 about the Y-axis direction as a rotation axis.
The second rotation mechanism 45 includes a pair of motors 451 provided on the third table 43 and having the Y-axis direction as a rotation axis, a bevel gear 452 attached to each rotation shaft of the pair of motors 451, a second A bevel gear 453 that is fixed to the table 42 and meshes with the bevel gear 452. By using the two motors 451 in this way, the second rotating mechanism 45 can obtain a high torque.

The third table 43 is provided with a bearing portion 454 that rotatably holds the shaft portion of the bevel gear 453.
According to the second rotation mechanism 45, the third table 43 can be rotated with respect to the second table 42 via the bevel gear 452 and the bevel gear 453 by driving the motor 451.

The finger unit 20 includes a fourth table 21 that can rotate with respect to the third table 43 of the articulated arm 32, and a rod-like finger 22 that is provided on the fourth table 21 so as to be able to advance and retract.
The fourth table 21 can be rotated by the third rotation mechanism 46 about the Y-axis direction as a rotation axis.

  The third rotation mechanism 46 is fixed to the fourth table 21 and is provided on the third table 43 and has a motor 461 whose rotation axis is the Z-axis direction, a bevel gear 462 attached to the rotation shaft of the motor 461, and the fourth table 21. A bevel gear 463 that meshes with the bevel gear 462.

The third table 43 is provided with a bearing portion 464 that rotatably holds the shaft portion of the bevel gear 463.
According to the third rotating mechanism 46, the fourth table 21 can be rotated with respect to the third table 43 via the bevel gear 462 and the bevel gear 463 by driving the motor 461.

The finger 22 can be advanced and retracted along the Z-axis direction by an advance / retreat mechanism 23.
The advance / retreat mechanism 23 includes a motor 231 provided on the fourth table 21 and a pinion gear 232 attached to the motor 231.

A rack 233 is formed in the finger 22 along the length direction, and the pinion gear 232 meshes with the rack 233. Further, a pressure sensor (not shown) for detecting an external force is provided on the distal end side of the finger 22, and this pressure sensor is connected to the control device 13 described above. The tip side of the finger 22 is coated with rubber to prevent damage to the workpiece.
According to the advancing / retracting mechanism 23, the finger 22 can protrude and retract with respect to the fourth table 21 via the pinion gear 232 and the rack 233 by driving the motor 231.

  The control device 13 optimizes the relative posture and interval between the fourth tables 21 of the finger unit 20 and the protruding dimension of the fingers 22 from the fourth table 21 according to the characteristics of the workpiece. Specifically, the hand 11 is operated based on a pressure value detected by a pressure sensor provided on the finger 22.

FIG. 4 is a perspective view showing the operation of the hand 11.
The articulated arm 32 can be moved along the first axis A, which is the linear movement axis in FIG. 4, by the slide mechanism 33, and the second table 42 is swung in FIG. 4 by the first rotation mechanism 44. It can rotate with respect to the 1st table 41 by making the 2nd axis | shaft B which is an axis | shaft into a rotation center. The third table 43 can be rotated with respect to the second table 42 about the third axis C, which is the pivot axis in FIG. 4, by the second rotating mechanism 45. The rotation mechanism 46 can rotate with respect to the third table 43 about the fourth axis D, which is the pivot axis, in FIG. Further, the finger 22 is movable along the fifth axis E, which is a linear motion axis in FIG.

The main functions of the first axis A to the fifth axis E are as follows.
By moving along the first axis A, the finger 22 can be moved to a position where the workpiece can be easily gripped. By rotating around the second axis B, the direction in which the fingers 22 are gripped can be adjusted. With the rotation about the third axis C and the fourth axis D, the gripping operation can be performed by adjusting the interval between the fingers 22 while keeping the fingers 22 parallel to each other. In particular, since the third axis C rotates with a higher torque than the fourth axis D, a larger gripping force can be obtained by rotating around the third axis C than when rotating around the fourth axis D. Can do.
By moving along the fifth axis E, it is possible to correspond to the height of the workpiece or approach the workpiece even when the clearance between the workpiece and the bucket is narrow. Further, by retracting the finger 22 along the fifth axis E, any finger 22 can be excluded from the gripping operation.

Next, a work gripped by the robot 1 will be described.
Examples of the workpiece include a shape that is particularly long in a predetermined direction and a thin plate shape. The workpieces having such a shape are accommodated together in a bucket. Examples of the work that is long in the predetermined direction include sash, molding, garnish, and lining.
In addition, the workpiece has a shape that is not particularly long in a predetermined direction, that is, a cube shape or a rectangular parallelepiped shape. Such a shaped work is provided with a partition in the bucket, and is accommodated one by one in a space surrounded by the partition. Examples of the cube-shaped workpiece include a mirror, an outer handle, a speaker, and a lock.

  As a method of gripping these workpieces with the robot 1, a method of gripping the workpiece by sandwiching the center of gravity of the workpiece with fingers (hereinafter referred to as a first gripping method) and a method of gripping the workpiece at a plurality of points (hereinafter referred to as a second method). Is called a gripping method).

In the first gripping method, since the center of gravity of the work is sandwiched between the fingers, at least two fingers are required.
In the second gripping method, one part of the workpiece is sandwiched by at least two fingers, and another part is gripped by the remaining fingers. Therefore, in this case, at least four fingers are necessary.

  When the number of fingers is three, for example, if there is a protrusion in the vicinity of the center of gravity of the workpiece, the center of gravity of the workpiece cannot be sandwiched between the fingers, and the workpiece may be rotated. Further, even when there are gaps for inserting fingers only at the four corners of the bucket in a state where the workpiece is housed in the box-shaped bucket, the center of gravity of the workpiece may not be sandwiched by the three fingers. Therefore, in the robot 1, four fingers 22 are provided, and the finger 22 is moved forward and backward by driving the advance / retreat mechanism 23, so that the finger 22 is selectively used according to the gripping method.

First, an operation for gripping a workpiece by the first gripping method will be described.
As shown in FIG. 5, the workpiece 50 has a substantially cross shape in plan view, and has a long base portion 501 and a protruding portion 502 provided at a substantially center of the base portion 501 and extending in a direction substantially orthogonal to the base portion 501. And comprising. This work 50 is accommodated in a bucket 51.
The bucket 51 has a box shape with the top opened, and includes a rectangular bottom portion 511 and a wall portion 512 erected on the periphery of the bottom portion 511.
When the workpiece 50 is accommodated in the bucket 51, four gaps 513 are formed between the periphery of the workpiece 50 and the wall portion 512 of the bucket 51.

  In the first gripping method, as shown in FIG. 5, the four fingers 22 are respectively inserted in the vicinity of the corners of the gap 513 of the bucket 51, and then the inserted fingers 22 are inserted into the base portion 501 of the workpiece 50. By moving toward the center, the center of gravity of the workpiece 50 is sandwiched between the four fingers 22.

When there is a protrusion on one end side of the workpiece, the operation for gripping the workpiece is as follows.
That is, as shown in FIG. 6, a protruding portion 502 is provided on one end side of the base portion 501 of the workpiece 50A. When the workpiece 50 </ b> A is accommodated in the bucket 51, the protrusion 502 is positioned near the corner of the bucket 51 in the gap 513 </ b> A.
Therefore, the finger 22 to be inserted into the gap 513A is inserted not near the corner of the gap 513A but near the center of the base 501 of the workpiece 50A.

Next, an operation for gripping a workpiece by the second gripping method will be described.
As shown in FIG. 7, in the second gripping method, the configuration of the workpiece 50 and the bucket 51 is the same as that of the first gripping method.
In this second gripping method, as shown in FIG. 7, first, the four fingers 22 of the hand 11 are each inserted into the gap 513 of the bucket 51. Next, the two fingers 22 positioned on one end side of the base portion 501 are moved toward the center line of the base portion 501 (indicated by a one-dot chain line in FIG. 7), thereby holding the one end side of the workpiece 50. Similarly, the two fingers 22 positioned on the other end side of the base portion 501 are moved toward the center line of the base portion 501, thereby sandwiching the other end side of the workpiece 50.

As a specific example of the first gripping method, an operation of gripping a mirror will be described.
The mirror is asymmetric in shape and has the larger depth dimension among the parts attached to the door. In addition, the medium parts are large and heavy. Furthermore, since the design property is high, it is necessary not to damage the outer surface.

As shown in FIG. 8, the bucket 61 has a box shape with the top opened, and includes a rectangular bottom portion 611 and a wall portion 612 erected on the periphery of the bottom portion 611. Further, the bucket 61 is provided with a partition 613 that partitions the internal space into three, and a mirror 60 is accommodated in each partitioned space.
The mirror 60 includes a mirror main body 601 to which a mirror is attached, and a support portion 602 provided on the mirror main body 601. A concave portion 603 is formed in a connection portion between the mirror main body 601 and the support portion 602 (see FIG. 9).

First, two of the four fingers 22 are arranged in the vicinity of the recess 603 of the mirror 60, and the remaining two are arranged in the mirror main body 601 of the mirror 60.
From this state, by moving the four fingers 22 toward the center of gravity of the mirror 60, the mirror 60 is held by the hand 11 as shown in FIG. 8, and then the hand 11 is lifted as shown in FIG. Then, the mirror 60 is lifted.

A procedure for gripping the sash will be described as a specific example of the second gripping method.
As shown in FIG. 10, the bucket 71 has a box shape with the top opened, and includes a rectangular bottom portion 711 and a wall portion 712 erected on the periphery of the bottom portion 711.
The sash 70 has a long shape with a substantially U-shaped cross section, and a plurality of sashes 70 are arranged in the bucket 71 so as to extend along the short direction of the bucket 71. In this state, the gap between the adjacent sashes 70 is narrow, and even if the finger 22 is lowered from above, the finger 22 does not reach the lower end side of the sash 70.

First, as shown in FIG. 10, two of the four fingers 22 are inserted into the gap between both ends of the sash 70 and the bucket 71.

  Next, as shown in FIG. 11, the two inserted fingers 22 are hooked on both ends of the sash 70 to raise the sash 70, and the side of the sash 70 that is opened in a substantially U-shape is directed upward. . Subsequently, when these two fingers 22 are moved toward the center side of the sash 70, the sash 70 faces upward, so that the tip of the finger 22 reaches the lower end side of the sash 70.

  Next, the remaining two fingers 22 are arranged at positions facing each other with the sash 70 sandwiched between the already inserted fingers 22, and the fingers 22 facing each other are brought closer to each other as shown in FIG. Then, the sash 70 is gripped by the hand 11. Then, as shown in FIG. 13, the hand 11 is raised and the sash 70 is lifted.

According to this embodiment, there are the following effects.
(1) By gripping the workpiece using the rod-like fingers 22 like chopsticks, it is possible to stably grip a workpiece such as the mirror 60 or the sash 70 having a different shape or center of gravity. Accordingly, since one robot 1 can grip and work on different workpieces without exchanging the hand 11, the manufacturing cost can be reduced with a simple configuration of the equipment for transporting the workpieces.

  (2) Since the workpieces such as the mirror 60 and the sash 70 can be gripped close to the tip end side of the finger 22, the wall portions 612 and 712 of the buckets 61 and 71 and the partition when the workpiece is gripped or released. Even if there is 613, the finger 22 is less likely to interfere with these wall portions 612 and 712 and the partition 613, and work can be performed efficiently.

  (3) Since the workpieces such as the mirror 60 and the sash 70 are gripped in the most stable state, the posture of the workpiece in the gripped state is not limited, so the posture of supplying the workpiece is not limited. Therefore, it is not necessary to be very nervous about the positioning accuracy of the workpiece supply.

  (4) Since the relative posture and interval between the fourth tables 21 and the projecting dimensions of the fingers 22 from the fourth table 21 are optimized according to the shape of the work such as the mirror 60 and the sash 70, the work Can be held stably.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

It is a figure which shows schematic structure of the workpiece | work holding apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows the structure of the hand of the workpiece | work holding apparatus which concerns on the said embodiment. It is a partial expansion perspective view of the hand of the workpiece holding device according to the embodiment. It is a perspective view which shows operation | movement of the hand which concerns on the said embodiment. It is a top view for demonstrating the 1st holding | grip method with the hand which concerns on the said embodiment. It is a top view for demonstrating the modification of the 1st holding | grip method with the hand which concerns on the said embodiment. It is a top view for demonstrating the 2nd holding | grip method with the hand which concerns on the said embodiment. It is a perspective view which shows the state which hold | gripped the mirror with the hand which concerns on the said embodiment. It is a perspective view which shows the state which lifted the mirror with the hand which concerns on the said embodiment. It is a perspective view which shows the state which inserted the finger which concerns on the said embodiment in the clearance gap between a sash and a bucket. It is a perspective view which shows the state which moved the finger which concerns on the said embodiment to the both ends side of a sash. It is a perspective view which shows the state which hold | gripped the sash with the hand which concerns on the said embodiment. It is a perspective view which shows the state which lifted the sash with the hand which concerns on the said embodiment.

Explanation of symbols

1 Robot (work gripping device)
11 hand 13 control device (control means)
14 Hand body 20 Finger part 21 Fourth table 22 Finger 30 Finger part adjusting mechanism (finger part adjusting means)
60 mirror (work)
70 Sash (work)

Claims (3)

A workpiece gripping device for gripping a workpiece with a hand,
The hand includes a hand main body, a plurality of finger parts, and a finger part adjusting means that is provided in the hand main body and changes a relative posture and interval between the plurality of finger parts,
Each of the plurality of finger portions includes a table supported by the finger portion adjusting means, and a bar-like finger provided on the table so as to be able to advance and retreat. The workpiece gripping device according to claim 1,
And further comprising control means for controlling the finger part adjusting means and the fingers,
The control means optimizes a relative posture and interval between the plurality of tables and a protruding dimension of the fingers from the table according to the shape of the workpiece. A workpiece gripping method for gripping a workpiece with a hand,
A plurality of finger portions are provided on the hand, and further, a table and a bar-like finger are provided on each finger portion,
A workpiece gripping method, wherein the workpiece is gripped by changing a relative posture and interval between the tables of the finger portion and moving the finger forward and backward from the table.

Images