JP2015229201A - Robot hand switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot hand switching device that reduces step change loss due to a shortened switching time, facilitates the avoidance of interference with a work environment, and has inexpensive system configuration.SOLUTION: A robot hand switching device according to the invention comprises: a driving source; a cam attached to the driving source; a lower rotation plate attached to the rotation shaft of the driving source; support posts provided at both ends of the rotation plate; a linear guide mounted on each support shaft; a cam follower rotated along the cam face of a cam; and a robot hand mounting part provided on each linear guide. The rotation shaft of the driving source is rotated, thereby, the cam follower is guided along the cam face by the linear guides, and a component gripping part mounted on the robot hand mounting part is rotated and moved upward/downward.

Description

  The present invention relates to a robot hand switching device for gripping a plurality of parts in a robot used in a production line or the like.

In recent years, with the diversification of customer demand and the globalization of the market, there has been a demand for variety-variable production that can cope with rapid changes in varieties and quantities. In response to this, there is an urgent need to develop an automated system for variable-variable production. In particular, highly versatile robots have been introduced into many production lines. In addition, various robot hand switching devices have been proposed in order to grip a wide variety of parts with a single robot.
As an example, there is a device that has a plurality of component gripping portions and switches the rotation of the component gripping portion by a cam mechanism or a turret hand (for example, Patent Documents 1 and 2). In addition, there is a hand switching device that handles gripping of a plurality of parts by exchanging the tip and hand of a robot arm with a detachable exchange (for example, Patent Document 3). Furthermore, a multi-fingered hand having a structure similar to that of a human hand has been developed (for example, Patent Document 4). In this case, by controlling the degree of bending of the finger by the drive source, it is possible to grip various types of parts without performing hand switching.

JP 2001-053492 A (page 4, left 14-28 line, FIG. 3) Japanese Unexamined Patent Publication No. 2000-334688 (Left page 4, lines 4-9, FIG. 1) Japanese Utility Model Laid-Open No. 7-11289 (page 1 left line 5-11, FIG. 1) JP 2008-178939 A (left side, lines 4 to 13, line 1 of FIG. 1)

As described above, production corresponding to the rapid fluctuation of the product type and quantity is required, and the gripping hand is switched in accordance with the shape of the part, so that reduction of the setup change loss is an issue. In addition, since a plurality of gripping hands are arranged, it is also a problem that it is easy to avoid interference with the work environment and can be configured with an inexpensive system.
In Patent Document 1, a plurality of suction nozzles and a nozzle holder for supporting the nozzles are attached to the periphery of the end face cam via a cam follower. Further, each of the end face cam and the nozzle holder is provided with a drive source, and the projecting surface of the end face cam is rotated to the position of the component by the drive source attached to the end face cam, and then attached to the nozzle holder. The nozzle holder is driven and rotated by the drive source, the suction nozzle to be used is rotated to the protruding surface of the end face cam, and the nozzle is switched. The switching device is installed between the conveyor and the pallet and used as a part of the component supply device. As described above, the rotational movement and switching are performed by the two drive sources, and a plurality of parts are gripped and carried. For this reason, the nozzle can be switched and the gripping component can be rotated and moved, which has the effect of reducing the setup change loss. On the other hand, since two drive sources are used, the apparatus becomes large. Therefore, it is difficult to avoid interference with the work environment, and the system configuration is expensive.

  Patent Document 2 has a turret structure, and multiple types of gripping hands can be gripped by arranging multiple types of gripping hands on the turret and rotating the gripping hands according to the part shape. It is. On the other hand, hands other than those in use are arranged in a horizontal direction or obliquely upward with respect to the used hands, so that it is difficult to avoid interference with the work environment as well as interference with the work. For this reason, when using as few as two gripping hands, the apparatus becomes large. Therefore, it is difficult to avoid interference with the work environment.

  Patent Document 3 has a mechanism that allows a plurality of gripping hands to be attached and detached by attaching a hand attaching / detaching adapter via a hand main body provided at the tip of a robot arm. The attachment / detachment method is performed by fitting the convex piston of the main body part and the concave cavity of the adapter part to form an air cylinder structure, and whether or not air is supplied. Switching hands can be shortened because the hand can be changed only by moving the piston up and down. On the other hand, when multiple gripping hands are required, the replacement hand is placed in a separate space, so that it takes time to move to pick up the hand in addition to the hand switching time, resulting in setup change loss. End up.

  Patent Document 4 has an articulated structure similar to a human finger. The number of fingers is composed of 3 to 4, and gripping is enabled by controlling the angle of each joint according to a plurality of parts having different shapes. Therefore, it is one of the advantages that a variety of products and a plurality of parts can be gripped without switching or replacing hands. However, in order to control the angle of each joint according to the part shape, a drive source is required for each joint, so that the equipment cost increases.

  The present invention has been made to solve the above-described problems, and is a robot hand that can easily avoid interference with the work environment, can reduce a setup change loss due to shortened switching time, and has a low system configuration. The purpose is to obtain a switching device.

  A robot hand switching device according to the present invention includes a drive source, a cam attached to the drive source, a lower rotary plate attached to a rotation shaft of the drive source, posts provided at both ends of the rotary plate, A linear guide mounted on the cam, a cam follower rotated along the cam surface of the cam, and a robot hand mounting portion provided on the linear guide. The cam follower is rotated by rotating the rotation shaft of the drive source. Moves along the cam surface, and the robot hand mounting portion is guided by a linear guide to rotate and move the robot hand mounting portion up and down.

  According to the present invention, since the rotation axis of the drive source and the robot hand are provided in parallel, it is easy to avoid interference in the work environment, and the rotation and lifting operations can be performed simultaneously with one drive source. It is possible to shorten the switching time of multiple hands, and it is small and can easily avoid interference with the workpiece, and the cam follower has no upper restraint and there is play. Even if it commits, the hand itself is not broken.

It is a conceptual diagram which shows the whole structure of the robot hand switching apparatus in Embodiment 1 of this invention. It is a front view which shows the principal part structure of the robot hand switching apparatus by Embodiment 1 of this invention. It is a front view explaining the use condition of the robot hand switching apparatus in Embodiment 1 of this invention. It is sectional drawing of the groove | channel cam and cam follower which are the principal parts of the robot hand switching apparatus in Embodiment 2 of this invention. It is a front view which shows the robot hand switching device in Embodiment 3 of this invention. It is the schematic explaining the view of the sliding resistance of the cam surface and cam follower in Embodiment 3 of this invention.

Embodiment 1
Hereinafter, the present invention will be described with reference to FIGS.
In addition, in each figure, the same code | symbol shall show the same or an equivalent part.

  FIG. 1 is a conceptual diagram showing a robot hand switching device according to Embodiment 1 of the present invention. A robot hand switching device 11 is attached to a robot arm 12 via a joint portion 13. As an example, the robot arm 12 is a horizontal articulated robot composed of a total of four axes including a linear motion axis J1 and three rotation axes J2, J3 and J4 parallel to the linear motion axis J1. Cite. A chuck-type gripping hand 14 a and a suction-type gripping hand 14 b are attached to both ends of the robot hand switching device 11.

Next, the detailed structure of the robot hand switching device 11 will be described with reference to FIG.
In the figure, a drive source 21 at the center of the apparatus is attached to an end face cam 22. The end face cam 22 is attached to the joint portion 13 at the distal end of the robot arm 12 via the right strut 26a, the left strut 26b, and the joint portion 27. A lower rotary plate 28 is attached to the rotation shaft of the drive source 21, and a right support plate 29 a and a left support plate 29 b for supporting a right linear guide 25 a and a left linear guide 25 b (not shown) are attached to both ends of the lower rotary plate 28. Is provided. In order to increase the rigidity, a rib 30 is attached to the right support plate 29a, the left support plate 29b, and the lower rotary plate 28, and an upper rotary plate 31 is attached to the right support plate 29a and the left support plate 29b. On each block of the right linear guide 25a and the left linear guide 25b, a right hand mounting portion 24a and a left hand mounting portion 24b are mounted. A right cam follower 23a and a left cam follower 23b are attached to the right hand attachment portion 24a and the left hand attachment portion 24b, respectively. The lower rotary plate 28, the support plates 29a and 29b, and the upper rotary plate 31 are integrally rotated by the drive source 21, and accordingly, the cam followers 23a and 23b are guided to the linear guides 25a and 25b and the end face cam 22. Will move up and down.
The robot hand is attached to the right hand attachment portion 24a and the left hand attachment portion 24b.

Next, description will be made with reference to FIG. 3 showing a usage state of the robot hand switching device 11.
In the figure, a conveyor 32 and a conveyor support part 33 are installed on the left side of the robot hand switching device 11, and a pallet 34 and a pallet support part 35 are installed on the right side. The conveyor 32 and the pallet 34 are arranged at different levels. A plurality of types of parts are conveyed on the conveyor 32. As an example, two types of parts 36 and 37 are shown. The part 36 is a flat part that cannot be chucked. The part 37 is a part that can be chucked.

Next, the operation will be described.
The robot hand switching device 11 moves to the position of the part to be grasped by the four axes of the robot arm 12. The robot hand switching device 11 switches between the chuck-type gripping hand 14a and the suction-type gripping hand 14b according to the part shape. The robot hand is switched when the chuck-type gripping hand 14a and the suction-type gripping hand 14b are rotated and moved up and down. The rotating shaft of the drive source 21 rotates, and the lower rotary plate 28, right support plate 29a, left support plate 29b, right linear guide 25a, left linear guide 25b, right hand mounting portion 24a, left hand mounting portion 24b, right The cam follower 23a, the left cam follower 23b, and the upper rotating plate 31 rotate simultaneously. Simultaneously with the rotation by the end face cam 22, the right cam follower 23a, the left cam follower 23b, the right hand mounting portion 24a and the left hand mounting portion 24b move up and down while sliding on the right linear guide 25a and the left linear guide 25b. Further, as shown in FIG. 3, a plurality of types of parts flowing on the conveyor 32 are gripped by the chuck-type gripping hand 14a and the suction-type gripping hand 14b, and are rotated and moved onto the pallet 34 having a different level. The gripping hand is switched simultaneously with the rotational movement.

According to such a configuration, the rotation shaft of the drive source 21, the chuck-type gripping hand 14a, and the suction-type gripping hand 14b can be attached in parallel. Therefore, it is possible to switch the robot hands without complicatedly arranging the robot hands that are not used, and it is easy to avoid interference in the work environment. Further, since the raising / lowering operation can be performed together with the rotation operation of the drive source 21, the switching time can be shortened, and the loss in the setup change can be reduced. Further, since the number of the drive sources 21 is one, the robot hand switching device 11 can have a small, lightweight, and inexpensive system configuration. Furthermore, since the cam followers 23a and 23b are not restrained in the upward direction and there is play even if a positioning error occurs, the robot hand is not damaged by the control error in the vertical direction.
It goes without saying that the number of robot hands attached can be expanded by increasing the diameter of the end face cam 22.

Embodiment 2. FIG.
In the second embodiment, as shown in FIG. 4, a groove cam 41 formed by forming a continuous groove on the side wall of the cylindrical body is used. Since the second embodiment is the same as the first embodiment except for the groove cam 41, the description of the entire structure is omitted here.
In FIG. 4, a right cam follower 23 a and a left cam follower 23 b are attached to the groove portion of the groove cam 41. Accordingly, the right cam follower 23 a and the left cam follower 23 b are restrained in the vertical direction by the upper and lower cam surfaces of the groove cam 41. The upper surface of the groove cam 41 is pressed by the upper rotary plate 31 and does not fall off.

Next, the operation will be described.
By rotating the drive source 21, the right cam follower 23 a and the left cam follower 23 b roll on the cam surface of the groove cam 41, and the rotation operation and the elevation operation are performed simultaneously.
On the other hand, since the right cam follower 23a and the left cam follower 23b are restrained in the vertical direction by the upper and lower cam surfaces by using the groove cam 41, the right cam follower 23a and the left cam follower 23b leave the cam surface even if the rotational speed is increased. The phenomenon of floating in the air does not occur. Therefore, the robot hand can be switched at a higher speed, and the switching time can be shortened. Further, by being restricted in the vertical direction, it can be attached not only to a horizontal articulated robot such as the robot arm 12 but also to a 6-axis robot arm, and the application range can be expanded.

Embodiment 3 FIG.
FIG. 5 shows a robot hand switching device according to Embodiment 3 of the present invention, in which a tension spring 51 is mounted between the right hand mounting portion 24a, the left hand mounting portion 24b and the upper rotating plate 31. . (The spring 51 on the left hand mounting portion 24b side is not shown because it does not appear in the drawing)
Next, the operation will be described.
The tension spring 51 lifts the right hand mounting portion 24a and the left hand mounting portion 24b. In addition, the tension spring 51, the right hand mounting portion 24a, the left hand mounting portion 24b, and the upper rotating plate 31 rotate with the rotation of the rotation shaft of the drive source 21.

In order to explain the effect of the tension spring 51, consider the case where the tension spring 51 is not provided.
As shown in FIG. 6, the load torque of the cam surface 61 and the cam follower 23 cannot be ignored. Load torque is calculated from the formula of force balance and moment balance.
It can be asked. Here, the distance from the center of the rotation axis of the drive source 21 to the cam follower 23 is d [m], the radius of the cam follower 23 is r [m], the reduction ratio of the drive source 21 is i, and the mass of the robot hand is m [kg]. ], The rolling friction coefficient is μ [m], the inclination angle is θ [deg], the gravitational acceleration is g [m / s ² ], the circumference of the cam surface is l ₁ , and the elevation distance is l ₂ .

On the other hand, by attaching the tension spring 52, the force applied to the cam surface can be made smaller than the gravity mg due to its own weight (mg-F) by using the restoring force (F> 0) of the spring. Since the apparent weight is reduced from m 1 to m ′ (<m), the load torque TL is reduced to m ′ / m times from Equation 1.
Further, since the sliding resistance is reduced, the load on the cam surface can be reduced, the durability of the cam is increased, and the life of the cam mechanism can be extended. Further, by using a constant load spring as the tension spring 52, it is needless to say that the apparent weight can be made uniform regardless of the hand lifting position, and the effect can be further exhibited. Furthermore, it goes without saying that the weights of both hands can be canceled by using the groove cam 41 instead of the end face cam 22.

In the above embodiment, the end face cam 22 or the groove cam 41 is used to configure the robot hand switching device. However, a linear cam that can slide the cam follower 23 in the vertical direction with rotation is used. May be.
In the present invention, the tension spring 51 is described as an example. However, if a restoring force works in a direction that reduces the force applied by the hand's own weight to the cam surface, an elastic body such as a compression spring is used. However, it goes without saying that the same effect can be obtained.
Further, the chuck-type gripping hand 14a and the suction-type gripping hand 14b are described as examples of the switching hands, but it goes without saying that the combination is free and the same effect can be obtained.
Furthermore, the present invention is not limited to the above embodiment, and can be appropriately modified and omitted without departing from the scope of the invention.

11: Robot hand switching device, 12: Robot arm,
13: Joint part, 14a: Chuck-type gripping hand,
14b: Suction type gripping hand, 21: Drive source, 22: End face cam,
23a, 23b: cam follower, 24a, 24b: hand mounting part,
25a, 25b: linear guide, 26a, 26b: support,
27: Joint part, 28: Lower rotating plate, 29a, 29b: Support plate,
30: Rib, 31: Upper rotating plate, 32: Conveyor,
33: Conveyor support part, 34: Pallet, 35: Pallet support part,
36, 37: Parts 41: Groove cam, 51: Robot hand switching device,
52: Extension spring 61: Cam surface.

Claims (6)

  Drive source, cam attached to the drive source, lower rotary plate attached to the rotation shaft of the drive source, support posts provided at both ends of the rotary plate, and linear guide attached to the support posts And a cam follower rotated along the cam surface of the cam, and a robot hand mounting portion provided on the linear guide, and rotating the rotation shaft of the drive source, the cam follower is A robot hand switching device characterized by moving along a cam surface and guiding a robot hand mounting portion by a linear guide to rotate and move the robot hand mounting portion up and down.   The robot hand switching device according to claim 1, wherein the cam is an end face cam.   The robot hand switching device according to claim 1, wherein the cam is a groove cam.   A rotating plate is provided on the top of the support column, and an elastic body that generates a restoring force in a direction that can reduce the force applied to the cam surface is attached between the upper rotating plate and the robot hand mounting portion. The robot hand switching device according to claim 2 or 3.   The robot hand switching device according to claim 4, wherein the elastic body is a constant load spring, and the pressing force against the cam due to the weight of the robot hand is canceled.   The robot hand switching device according to any one of claims 1 to 5, wherein a pair of the cam followers rotated along the cam surface of the cam is paired.