JP2012096305A - Bracket for robot arm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bracket for a robot arm capable of accurately positioning an operating member.SOLUTION: The bracket 4 for the robot arm includes a shaft-like member 6 fixed to a tip of the robot arm 1. The shaft-like member 6 has a vertically extended body 7, and a lower flange 9 hanging from a lower end of the body 7 over the surrounding thereof. The bracket 4 for the robot arm includes a movable plate 12. A through-hole 15 is formed at the movable plate 12. The body 7 of the shaft-like member 6 is inserted into the through-hole 15, and the movable plate 12 is disposed above the lower flange 9. An upper face of the lower flange 9 is provided with six steel balls 11 protruded upward from the upper face of the lower flange. The movable plate 12 is elastically urged downward by a coil spring 18, and supported by the steel balls 11 from below.

Description

  The present invention relates to a bracket for attaching an action member (such as a clamp mechanism for holding a workpiece) acting on a workpiece to a robot arm.

  Small articulated robots, which are a type of industrial robot, are used, for example, as welding robots for welding steel plates and transfer robots for carrying in and out machined objects in production plants for automobiles and automobile parts. ing.

  FIG. 4 is a schematic sectional view of a conventional robot arm bracket.

  The robot arm bracket 101 is fixed to the wrist shaft 100 extending in the vertical direction at the tip of the robot arm. The robot arm bracket 101 is fixed to the lower end of the wrist shaft 103 and has a substantially cylindrical fixed cylindrical portion 102 extending in the vertical direction. The robot arm bracket 101 is fixed to the lower end of the fixed cylindrical portion 102 and is fixed to a substantially circular plate having a horizontal posture. A plate 103 and a substantially disc-shaped movable plate 104 facing the fixed plate 103 from below are provided.

  A through hole 105 is formed at the center of the fixed plate 103. Six holding holes 106 are formed at equiangular intervals around the center of the fixed plate 103 at the peripheral edge of the lower surface of the fixed plate 103. A steel ball 107 is rotatably held in each holding hole 106.

  A receiving hole 108 having a V-shaped cross section is formed on the upper surface of the movable plate 104 at a position facing each steel ball 107. A support bolt 109 is fixed to the central portion of the movable plate 104. The support bolt 109 extends above the movable plate 104, is inserted through the through hole 105, and protrudes into the fixed cylindrical portion 102. A coil spring 110 is interposed between the upper end of the support bolt 109 and the fixed plate 103 in a compressed state. Due to the elastic force of the coil spring 110, the movable plate 104 is biased toward the fixed plate 103, the steel balls 107 are fitted into the receiving holes 108, and the movable plate 104 is positioned with respect to the fixed plate 103.

  For example, an industrial robot provided with the robot arm bracket 101 plays a role as a welding robot by attaching a welding torch as an action member acting on a workpiece to the movable plate 104. Since the movable plate 104 is elastically supported by the fixed plate 103 via the coil spring 110, for example, when the welding torch contacts another member during movement, the movable plate 104 is inclined with respect to the fixed plate 103. It is displaced to. Therefore, if a means for detecting the displacement of the movable plate 104 is provided, the operation of the welding robot can be stopped in response to the detection of the displacement of the movable plate 104, and the welding torch is forcibly moved. This can prevent the wrist shaft 103 from being damaged.

Japanese Utility Model Publication No. 62-131791

  However, since the welding torch is attached to the movable plate 104 and the movable plate 104 is elastically supported by the fixed plate 103 via the coil spring 110, the welding torch is moved when the welding torch is moved to a predetermined position. There is a possibility that the position of the welding torch cannot be accurately positioned at a predetermined position due to shaking with the movable plate 103.

  The objective of this invention is providing the bracket for robot arms which can position an action member accurately.

  In order to achieve the above object, the present invention provides a bracket for attaching an action member acting on a workpiece to a robot arm, a main body portion fixed to the tip of the robot arm and extending in the vertical direction, and a lower end portion of the main body portion. A shaft-shaped member having a flange projecting from the periphery, at least three protrusions provided on the upper surface of the flange and projecting upward with respect to the upper surface, and an insertion through which the main body of the shaft-shaped member is inserted A movable plate having a hole, disposed above the flange, supported from below by the protrusion, and to which the working member is attached; and a biasing member that elastically biases the movable plate downward It is characterized by providing.

  The robot arm bracket includes a shaft-like member fixed to the tip of the robot arm. The shaft-shaped member has a main body portion extending in the vertical direction and a flange projecting from the lower end portion of the main body portion to the periphery thereof. The robot arm bracket includes a movable plate. An insertion hole is formed in the movable plate. The main body portion of the shaft-like member is inserted into the insertion hole, and the movable plate is disposed above the flange. Then, at least three protrusions projecting upward from the upper surface are provided on the upper surface of the flange. The movable plate is elastically urged downward by the urging member and is supported from below by the protrusion.

  Thereby, the movable plate is fixed to the flange of the shaft member by the biasing force of the biasing member. Therefore, when the action member is attached to the movable plate and the action member is moved to a predetermined position, the action member can be prevented from shaking with the movable plate, and the action member can be accurately positioned at the predetermined position. .

  Further, when the action member comes into contact with another member during the movement, the movable plate is displaced against the biasing force of the biasing member. Therefore, if a means (sensor, switch, etc.) for detecting the displacement of the movable plate is provided, the operation of the robot arm can be stopped in response to the detection of the displacement of the movable plate. It is possible to prevent the robot arm from being damaged by being forcibly moved.

  The main body portion of the shaft-shaped member is preferably formed in a cylindrical shape. Thereby, the wiring for the electric power feeding to an action member, etc. can be connected to an action member through the main-body part of a shaft-shaped member.

  According to the present invention, the action member attached to the movable plate can be accurately positioned at a predetermined position, but the action of the robot arm can be stopped when the action member comes into contact with another member during the movement. It is possible to prevent the robot arm from being damaged by forcibly moving the action member.

FIG. 1 is a plan view of a robot arm bracket and a clamp mechanism attached thereto according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the robot arm bracket and the clamp mechanism shown in FIG. 1 and shows a state in which the workpiece is held horizontally. FIG. 3 is a cross-sectional view of the robot arm bracket and the clamp mechanism shown in FIG. 1 and shows a state in which the workpiece collides with another member during conveyance and the workpiece is inclined. FIG. 4 is a schematic sectional view of a conventional robot arm bracket.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view of a robot arm bracket and a clamp mechanism attached thereto according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the robot arm bracket and the clamp mechanism shown in FIG. 1 and shows a state in which the workpiece is held horizontally. FIG. 3 is a cross-sectional view of the robot arm bracket and the clamp mechanism shown in FIG. 1 and shows a state where the workpiece collides with another member during the movement and the workpiece is inclined.

  As shown in FIGS. 2 and 3, a wrist shaft 2 extending in the vertical direction is provided at the tip of the robot arm 1 so as to be movable up and down. The wrist shaft 2 is a cylindrical hollow shaft, and a flange 3 projecting to the periphery is formed at a lower end portion thereof. A clamp mechanism 5 for holding the workpiece W is attached to the wrist shaft 2 via a robot arm bracket 4.

  The robot arm bracket 4 includes a shaft-like member 6. The shaft-shaped member 6 includes a cylindrical main body portion 7 extending in the vertical direction, an upper flange 8 projecting from the upper end portion of the main body portion 7 to the periphery, and a lower flange 9 projecting from the lower end portion of the main body portion 7 to the periphery. It has one. The shaft-like member 6 is attached to the wrist shaft 2 by fixing the upper flange 8 to the flange 3 of the wrist shaft 2.

  On the upper surface of the lower flange 9, six holding holes 10 are formed at equal intervals (at equal angular intervals) in the circumferential direction of the main body portion 7. A steel ball 11 is rotatably held in each holding hole 10. The upper half portion of the steel ball 11 protrudes upward with respect to the upper surface of the lower flange 9 as a protrusion.

  A movable plate 12 is provided above the lower flange 9. As shown in FIG. 1, the movable plate 12 includes a plate body portion 13 having a substantially rectangular shape in plan view, and an extension extending from the two adjacent corner portions of the plate body portion 13 on a diagonal extension of the plate body portion 13. It is in the form of a thin plate integrally having the portion 14.

  A circular insertion hole 15 is formed in the center of the plate body 13 as shown in FIGS. The body portion 7 of the shaft-like member 6 is inserted into the insertion hole 15 with play.

  On the lower surface of the plate body 13, a receiving hole 16 having a pentagonal cross section (home base shape) opened downward is formed at a position facing each steel ball 11.

  On the upper surface of the plate body 13, a spring accommodating portion 17 having a substantially U-shaped cross section is formed at the same position as each steel ball 11 in plan view. A coil spring 18 is accommodated in the spring accommodating portion 17. The upper end portion of the coil spring 18 is fixed to the upper flange 8 of the shaft-like member 6, and is interposed between the upper flange 8 and the bottom portion of the spring accommodating portion 17 in a compressed state. The movable plate 12 is biased downward by the elastic force of the coil spring 18, the inner surface of the receiving hole 16 of the movable plate 12 abuts on the steel ball 11, and the movable plate 12 is elastically supported by the steel ball 11. Yes.

  Two positioning holes 19 are formed on the upper surface of the workpiece W. Positioning pins 20 are provided at the distal ends of the extending portions 14 of the movable plate 12 so as to correspond to the positioning holes 19. The positioning pin 20 extends downward from the extending portion 14. The movable plate 12 is positioned with respect to the workpiece W by fitting the positioning pins 20 into the positioning holes 19.

  The clamp mechanism 5 includes a plurality of upper clamp members 21. A plurality of clamping portions 22 are formed on the workpiece W. The upper clamp member 21 is provided corresponding to each clamping portion 22, is attached to the plate main body portion 13 of the movable plate 12, and extends downward from the plate main body portion 13.

  The clamp mechanism 5 includes a rotary cylinder 23 and a lower clamp member 24. The rotary cylinder 23 is attached to the plate body 13 of the movable plate 12 such that the rod 26 extends downward from the cylinder body 25. The lower clamp member 24 is fixed to the distal end portion of the rod 26 of the rotary cylinder 23. The lower clamp member 24 is formed in a thin plate shape that extends in the direction orthogonal to the advancing / retreating direction of the rod 26 from the distal end portion of the rod 26.

  When the workpiece W is held by the clamp mechanism 5, the robot arm 1 is moved, and the movable plate 12 is placed on the workpiece W so that each upper clamp member 21 faces the clamping portion 22 of the workpiece W vertically upward. It is arranged at a predetermined position above. Thereafter, the wrist shaft 2 is lowered, and each upper clamp member 21 is pressed against the clamping portion 22. At this time, the lower clamp member 24 is retracted to a position where it does not contact the workpiece W. When the upper clamp member 21 is pressed against the holding portion 22, the lower clamp member 24 is disposed at a position facing the one holding portion 22 from below by the rotation of the rod 26 of the rotary cylinder 23. Then, the lower clamp member 24 is pressed against the clamping portion 22 by contraction of the rod 26 of the rotary cylinder 23. As a result, the clamping part 22 is clamped by the upper clamp member 21 and the lower clamp member 24, and the holding of the workpiece W by the clamp mechanism 5 is achieved.

  A micro switch 27 is attached to the robot arm bracket 4. Specifically, a support member 28 having an L-shaped cross section is fixed to the upper flange 8 of the shaft-shaped member 6 and extends in the horizontal direction from the upper surface thereof and bends downward. As shown in FIG. 2, the microswitch 27 is configured such that the movable plate 12 is in a horizontal posture, and the actuator 29 at the tip is opposed to the outer surface of the spring accommodating portion 17 with a minute gap, or The support member 28 is supported by a portion extending in the vertical direction so that the actuator 29 comes into contact with the outer surface of the spring accommodating portion 17.

  For example, the work W machined by the machine tool is transferred to another machine tool by the actions of the robot arm 1 and the clamp mechanism 5. The workpiece W or the clamp mechanism 5 (lower clamp member 24) may collide with another member during conveyance due to a teaching mistake with respect to the control device that controls the movement of the robot arm 1 or the like. When the workpiece W or the clamp mechanism 5 collides with another member, the movable plate 12 is displaced from the horizontal posture to the inclined posture together with the workpiece W, as shown in FIG. By this displacement, the outer surface of the spring accommodating portion 17 is strongly pressed by the actuator 29 of the micro switch 27, and the micro switch 27 is turned on. When the micro switch 27 is turned on, in response thereto, it is determined that the workpiece W or the clamp mechanism 5 has collided with another member, and the operation of the robot arm 1 is stopped.

  As described above, the robot arm bracket 4 includes the shaft-like member 6 fixed to the tip of the robot arm 1. The shaft-like member 6 has a main body portion 7 extending in the vertical direction and a lower flange 9 projecting from the lower end portion of the main body portion 7 to the periphery thereof. Further, the robot arm bracket 4 includes a movable plate 12. An insertion hole 15 is formed in the movable plate 12. The main body 7 of the shaft-like member 6 is inserted into the insertion hole 15, and the movable plate 12 is disposed above the lower flange 9. And on the upper surface of the lower flange 9, six steel balls 11 projecting upward from the upper surface are provided. The movable plate 12 is elastically biased downward by a coil spring 18 and supported from below by a steel ball 11.

  Thereby, the movable plate is elastically fixed to the lower flange 9 of the shaft-like member 6 by the biasing force of the coil spring 18. Therefore, when the clamp mechanism 5 is attached to the movable plate 12 and the clamp mechanism 5 is moved to a predetermined position above the workpiece W, the clamp mechanism 5 can be prevented from shaking together with the movable plate 12. Can be accurately positioned at a predetermined position.

  Further, when the micro switch 27 is turned on due to the displacement of the movable plate 12, in response to this, it is determined that the workpiece W or the clamp mechanism 5 has collided with another member, and the operation of the robot arm 1 is stopped. Thereby, the wrist shaft 2 and the like can be prevented from being damaged by the robot arm 1 being forcibly moved after the workpiece W or the clamp mechanism 5 collides with another member.

  The main body portion 7 of the shaft-like member 6 is formed in a cylindrical shape. The wrist shaft 2 is a cylindrical hollow shaft. Thereby, the wiring for supplying power to the rotary cylinder 23 can be connected to the rotary cylinder 23 by passing through the wrist shaft 2 and the main body portion 7 of the shaft-like member 6, and drawing downward from the main body portion 7. Therefore, the wiring to the rotary cylinder 23 can be easily routed.

  Although one embodiment of the present invention has been described above, various design changes can be made to this embodiment within the scope of the matters described in the claims.

1 Robot arm 4 Robot arm bracket 5 Clamp mechanism (working member)
6 Shaft-shaped member 7 Body 9 Lower flange (flange)
11 Steel balls (protrusions)
12 Movable plate 15 Insertion hole 18 Coil spring (biasing member)
20 Positioning pin (action member)
21 Upper clamp member (action member)
23 Rotary cylinder (working member)
24 Lower clamp member (action member)

Claims (2)

A bracket for attaching an action member acting on a workpiece to a robot arm,
A shaft-like member having a flange fixed to the tip of the robot arm and extending in the vertical direction and a flange projecting from the lower end of the main body,
At least three protrusions provided on the upper surface of the flange and projecting upward with respect to the upper surface;
A movable plate having an insertion hole through which the main body portion of the shaft-shaped member is inserted, disposed above the flange, supported from below by the protrusion, and to which the action member is attached;
A robot arm bracket including a biasing member that resiliently biases the movable plate downward.   The robot arm bracket according to claim 1, wherein the main body portion of the shaft-shaped member is formed in a cylindrical shape.

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