JPH1199494A - Robot hand for spot welding and work holding method by this robot hand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold even works different in shapes without enlarging and increasing cost of a device. SOLUTION: It is possible to hold a work by a welding gun 3 and two clamp units 13 at three points after welding the work by the spot welding gun 3. A clamp chip 67 of the clamp unit 13 has a spherical surface on its head end and electrode chips 21, 23 have also spherical surfaces on their head ends in the same way, and accordingly, it is possible to hold the work regardless of its shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding robot hand having a spot welding gun and clamping means for gripping a workpiece, and a method of gripping a workpiece by the robot hand.

[0002]

SUMMARY OF THE INVENTION An object of the present invention is to enable a workpiece having a different shape to be gripped without increasing the size and cost.

[0003]

In order to achieve the above object, according to the present invention, a spot welding gun is provided on a hand base attached to a tip shaft of a robot, and a workpiece to be welded by the spot welding gun. Are provided, and the three clamp means have a spherical holding structure in which the positional relationship between the holding portions corresponds to three vertices of a triangle, and the work is held and fixed from both sides. Section.

According to the robot hand for spot welding having such a configuration, the work spot-welded by the spot welding gun is gripped by three clamping means and transported to the next step. At this time, each clamping means has a spherical shape. The workpiece is clamped and fixed by the clamping section.

According to a second aspect of the present invention, in the configuration of the first aspect, one of the three clamping means is also used as a spot welding gun.

According to the above construction, the work welded by the spot welding gun is clamped and fixed by the spot welding gun and the other two clamping means.

According to a third aspect of the present invention, in the configuration of the second aspect of the present invention, the two clamping means are configured to avoid interference with the workpiece at the workpiece gripping position for gripping the workpiece and at the time of welding work by the spot welding gun. The workpiece can be moved between a retreat position and a position farther from the spot welding gun than the work holding position.

According to the above configuration, during welding work on the workpiece by the spot welding gun, the two clamping means are located at the retracted positions away from the spot welding gun, so that interference with the workpiece is avoided, and the spot-welded workpiece is removed. At the time of gripping, the workpiece is brought close to the spot welding gun to a workpiece gripping position and grips the workpiece together with the spot welding gun.

According to a fourth aspect of the present invention, in the configuration of the first or second aspect, each of the clamping means is individually arranged such that a relative position with respect to other clamping means can be displaced when gripping a workpiece. It has an equalizing mechanism.

According to the above arrangement, the relative position of each clamp means with respect to the other clamp means is changed by the equalizing mechanism, so that the clamp means easily follows the shape or posture of the work.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, each of the equalizing mechanisms includes a brake mechanism for fixing a relative position with respect to another clamping means while gripping the work.

According to the above configuration, by locking the brake mechanism of the equalizing mechanism in a state where the work is gripped by the clamp means, the relative positions of the respective clamp means are fixed, and the gripping posture during the transfer of the work is stabilized.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect of the present invention, each of the clamping means is provided with an encoder for detecting a posture of the work in a state of gripping the work in which the equalizing mechanism is fixed by the brake mechanism. The operation of the robot is controlled so that the workpiece is in a normal posture based on the detected data.

According to the above construction, the posture of the work in the state of gripping the work, to which the equalizing mechanism is fixed by the brake mechanism, is detected by the encoder, and the robot is controlled based on the detected data to correct the work to the normal posture. Is done.

According to a seventh aspect of the present invention, after a workpiece is spot-welded with a spot welding gun provided on a robot tip shaft,
The workpiece is gripped by three gripping portions located at the vertices of a triangle between the spot welding gun and two clamping means having spherical clamping portions for clamping and fixing the workpiece from both sides.

According to the above-described work holding method, the work after spot welding is clamped and fixed by the three-point support by the spot welding gun and the two clamping means having the spherical clamping portion. The work can be gripped and transported to the next process.

[0017]

According to the first aspect of the present invention, the work to be spot-welded by the spot welding gun is conveyed while being gripped by the three clamping means. Since the work is clamped and fixed by three-point support corresponding to the three vertices of the triangle, it is possible to grip a work of various shapes and improve versatility.

According to the second aspect of the present invention, when a workpiece is gripped, a spot welding gun is also used as a clamping means in addition to the two clamping means, so that one dedicated clamping means is not required, and the robot hand is not required. Can be reduced in size.

According to the third aspect of the present invention, at the time of welding work on the workpiece by the spot welding gun, interference with the workpiece can be avoided by setting the two clamping means to the retracted position away from the spot welding gun. it can.

According to the fourth aspect of the present invention, since each clamp means changes its relative position with respect to other clamp means by the equalizing mechanism when gripping the work, it easily follows the shape or posture of the work. be able to.

According to the fifth aspect of the present invention, the relative position of each clamp means holding the work is fixed by the brake mechanism of the equalizing mechanism, so that the work holding posture is stabilized and the work is reliably transported. be able to.

According to the sixth aspect of the present invention, the posture of the work in the state of gripping the work with the equalizing mechanism fixed by the brake mechanism is detected by the encoder, and the robot is controlled based on the detected data so that the work can be made regular. Since the posture is corrected, it is effective for work requiring positioning accuracy, such as setting a gripped work on a jig.

According to the seventh aspect of the present invention, the workpiece after spot welding is clamped and fixed by the three-point support of the spot welding gun and two clamping means having spherical clamping portions, so that the workpiece has various shapes. The work can be gripped, and versatility can be improved.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a robot hand for spot welding showing one embodiment of the present invention. A hand base 7 is provided between the robot tip shaft 1 and a welding transformer 5 attached to a spot welding gun (hereinafter, simply referred to as a welding gun) 3. The hand base 7 has a tip shaft fixing surface 9 to which the tip (lower end) of the robot tip shaft 1 is fixed.
A transformer fixing surface 11 at the end of the tip shaft fixing surface 9 opposite to the welding gun 3, which is bent downward in the figure to fix the rear end of the welding transformer 5 to the lower inner surface; A clamp holding arm 15 protrudes from the end opposite to the transformer fixing surface 11 of the shaft fixing surface 9 to both left and right sides, and holds a clamp unit 13 as a clamp unit described later.

The welding gun 3 has a fixed-side gun arm 17 and a movable-side gun arm 19.
Electrode tips 21 and 23 are provided at the tip of 19 respectively. The gun arms 17 and 19 have base ends mounted on holders 25 and 27, respectively, and the lower holder 2
5 is a bracket 29 attached to the welding transformer 5
The holding member 27 on the upper side is supported rotatably about a support shaft 31 provided at the front end of the bracket 29.

A cylinder mounting bracket 33 is provided on the upper surface of the welding transformer 5, and a gun pressurizing cylinder 35 is rotatably mounted on the cylinder mounting bracket 33 via a pin 37. The piston rod 39 of the gun pressurizing cylinder 35 is rotatably mounted via a pin 43 on a bracket 41 provided on the holder 27 on the upper side. Is rotated in the direction of arrow A about the center, and spot welding is performed between the electrode tips 21 and 23, and the workpiece W is also provided with a function of holding and fixing the work W.

Clamp holding arm 15 of hand base 7
Has a bent portion 45 bent downward, and the bending portion 45 has a swinging piece 49 that can swing around a hinge 47 as a fulcrum.
Is provided. The bent portion 45 has a slit 51 into which the upper end of the swinging piece 49 is inserted, and a lower end corner on the transformer fixing surface 11 side is formed in an R shape. Swing displacement is possible.

An actuator mounting bracket 53 is provided at the upper end of the bent portion 45 on the R-shaped side. A swing actuator 55 is rotatably mounted on the mounting bracket 53 via a pin 56. ing.
The piston rod 57 of the swing actuator 55
Is pivotally mounted via a pin 61 to a bracket 59 provided on the transformer fixing surface 11 side of the rocking piece 49 so that the rocking piece 49 is moved in the direction of arrow B by the operation of the swing actuator 55. Rocks.

At the lower end of the swinging piece 49, a clamp actuator 63 is mounted.
Drives the pair of clamp arms 65 so that the clamp tips 67 provided on the mutually opposing sides of the distal ends move closer to and away from each other. The clamp tip 67 has a spherical end portion, and the workpiece W is sandwiched and fixed by the spherical portion, and together with the electrode tips 21 and 23 having a function of gripping the workpiece W described above, the clamp portion 67 has a spherical holding portion. Constitute. The three gripping portions (holding portions) including the electrode tips 21 and 23 and the two clamp tips 67 have a mutual positional relationship corresponding to three vertices of a triangle, respectively.

FIG. 2 is a sectional view showing the internal structure of the clamp actuator 63.
Reference numeral 3 denotes a first piston 71 slidable in the left-right direction at a central position in the body 69, and a second piston provided on the outer periphery of the first piston 71 and relatively movable in the same direction as the first piston 71. 73 are accommodated. Each of the pair of clamp arms 65 has a protruding portion 65a protruding at a base end in a direction facing each other. The left end of the first piston 71 in the drawing is connected to the protruding portion 65a via a shaft 75, and the clamp arm 65 rotates about the support shaft 77 by the movement of the first piston 71. Second piston 73
Pressing piece 79 attached to the end of the
Are in a state where they can contact the side roller 80 provided on the rear end side of the clamp arm 65.

Between the rear end of the first piston 71 and the cap 81, a first pressure chamber 83 is formed.
A second pressure chamber 85 is formed between the outer periphery of 3 and the body 69.

In the state shown in FIG. 2, when air is supplied to the second pressure chamber 85 through the air port 87 and air is discharged from the first pressure chamber 83 through the air port 89, the first piston 71 is moved in the figure. At the same time as the rightward movement, the second piston 73 moves leftward in the drawing, whereby the clamp arm 65 moves so that the clamp tips 67 at the tip end approach each other as shown in FIG. W is ready to be gripped.

Conversely, from the state of FIG. 3, air is supplied to the first pressure chamber 83 through the air port 89 and the second pressure chamber 8
When the air is discharged from the air port 5 through the air port 87, the first piston 71 moves to the left in the figure and the second piston 73 moves to the right in the figure. The arm 65 moves in the direction in which the clamp tips 67 move away from each other, and returns to the state shown in FIG.

In the spot welding robot hand having the above-described configuration, the workpiece W spot-welded by the welding gun 3 is gripped at three places of the two clamping units 13 and the welding gun 3, and is conveyed to the next step. . When performing spot welding, the swing actuator 55 is driven from the state shown in FIG. 1 and its piston rod 57 is retracted upward in FIG. 1 so that the swinging piece 49, the clamp actuator 63, the clamp arm 65, etc. The swing movement of the clamp unit 13 is performed rearward, so that the welding operation can be performed without the clamp unit 13 being in the way.

After the spot welding, the swing actuator 55 is driven so that the piston rod 57 advances downward, and the clamp unit 13 swings forward so as to be in the state shown in FIG. In this state, the clamp actuator 63 is driven from the state shown in FIG. 2 to the state shown in FIG. 3 to clamp and fix the work W with the clamp tip 67, and the operation of the gun pressing cylinder 35 in the welding gun 3 as well. As a result, the gun arm 19 is
Move downward from the state away from the
23, the work W is clamped and fixed.

In the two clamp units 13, the tips of the clamp tips 67 are spherical, and the tips of the electrode tips 21 and 23 of the welding gun 3 are also spherical, and the work W is held at these three points. Since it is gripped, there is no need to change the gauge for each work as in the case of using a gauge that matches the shape of the work, and it can flexibly respond to the shape of the work and has high versatility It has become. Further, since the welding gun 3 is used as one of the clamping means, the size and cost of the robot hand can be reduced as compared with the case where three dedicated clamping means are provided.

FIG. 4 is a perspective view of a spot welding robot hand showing another embodiment of the present invention, and FIG. 5 is a side view of the same. In the spot welding robot hand, a hand base 97 is provided between a robot tip shaft 91 and a welding transformer 95 attached to a welding gun 93, as in the case of FIG. The hand base 97 has a tip shaft fixing surface 9 to which the tip (lower end) of the robot tip shaft 91 is fixed.
9 and a transformer fixing surface 111 to which the rear end of the welding transformer 95 is mounted on the inner surface of the lower end side of the tip shaft fixing surface 99, which is bent downward at the end opposite to the welding gun 93 in the drawing.
And a clamp unit holding piece 115 that protrudes from the end opposite to the transformer fixing surface 111 of the tip shaft fixing surface 99 to both right and left sides and holds a clamp unit 113 as a clamp unit described later.

The welding gun 93 is mounted on the fixed-side gun arm 11.
7 and the tip of the movable-side gun arm 119 are provided with electrode tips 121 and 123, respectively.
17 and 119 have their base ends attached to holders 125 and 127, respectively. The upper holding member 127 is rotatably supported by a lower holding member 125 about a support shaft (not shown) provided at the tip of a bracket 129 attached to the welding transformer 95, whereby the gun arm 11 is
Numeral 9 is movable in a direction approaching and moving away from the gun arm 117. The holding tool 127 and the lower holding tool 125
Are the electrode tips 12 at the tips of the gun arms 117 and 119.
While the workpiece W is gripped by the workpieces 1 and 123, the workpieces W can be integrally rotated with each other.
An equalizing mechanism that functions so that a relative position with respect to another clamping means can be displaced when a workpiece is gripped. The rotation position of the holders 125 and 127 is determined by the rotary encoder 131 provided at the tip of the bracket 129.
Can be detected by the rotary encoder 13.
1 is provided with a brake mechanism for fixing the gun arms 117 and 119 at appropriate rotation positions.

The gun pressurizing cylinder 133 for driving the movable gun arm 119 is provided with a bracket 13 at the tip of a support piece 135 projecting obliquely upward from the lower holder 125.
7 and the piston rod 139
Of the bracket 1 provided on the holder 127 on the upper side
41 is rotatably connected via a pin 143.

The clamp unit holding piece 115 is provided with a swinging piece 149 that can swing with the hinge 147 as a fulcrum. The clamp unit holding piece 115 is
A slit 151 into which the base end of the base 49 is inserted is formed, and a tip corner on the transformer fixing surface 111 side is formed in an R shape, so that it can be turned to the transformer fixing surface 111 side from the state of FIG. I have.

A bracket 153 is formed so as to protrude from the corner of the rocking piece 149 on the side of the transformer fixing surface 111 at the side of the transformer fixing surface. Is provided with an actuator mounting bracket 155 protruding therefrom. A swing actuator 15 is attached to the actuator mounting bracket 155.
7 is rotatably mounted via a pin 159, and the tip of a piston rod 161 of the swing actuator 157 is rotatably mounted on the bracket 153 via a pin 163.
7. The clamp unit 1 including the rocking piece 149 by the operation of 7.
13 is one clamp unit 11 in FIG.
As shown in the plan view of FIG.
Swinging in the direction of arrow C about.

The clamp unit 113 is mounted on the frame 16
The frame 165 includes a central portion 165a that extends vertically, and upper and lower arms 165b and 165c that extend in parallel with the tip shaft fixing surface 99 at both upper and lower ends of the central portion 165a. Upper arm 165
The upper and lower ends of two guide rods 167 are connected and fixed to a portion of the lower arm 165c protruding toward the swinging piece 149, and the guide rod 167 is slidable vertically with respect to the swinging piece 149. Supported. Springs 169 and 171 are interposed on the upper side and lower side of the swinging piece 149 of the guide rod 167, respectively, and the overall elasticity of the springs 169 and 171 causes the entire clamp unit 113 for the swinging piece 149 to move. Are held elastically at the positions shown in FIG. Thus, the structure in which the clamp unit 113 is elastically held so as to be movable in the vertical direction corresponds to an equalizing mechanism that functions so that the relative position with respect to other clamping means can be displaced when gripping the work. I do.

A linear encoder 175 provided with a brake mechanism, which is movable up and down along a guide rail 173 formed on the side of the central portion 165a, is provided at an end of the tip of the swinging piece 149 opposite to the bracket 153. Is provided.

Upper arm 165 of frame 165
At the tip of the part protruding on the side opposite to the rocking piece 149 of b,
The clamp actuator 177 is mounted. A clamp tip 181 is formed at the tip of the piston rod 179 of the clamp actuator 177, and the lower arm 1
A clamp tip 183 that clamps and fixes the work W with the clamp tip 181 is provided at an end of the 65 c protruding on the opposite side to the swinging piece 149.

In the spot welding robot hand as shown in FIG. 4, the work W spot-welded by the welding gun 93 is connected to the two clamping units 113 and the welding gun 93 in the same manner as in FIG. And transport to the next process. When performing spot welding, the swing actuator 157 is driven to move the clamp unit 113 including the rocking piece 149 from the state shown in FIG. 4 and the state shown by the solid line in FIG. The piston rod 161 is retracted so as to swing backward, so that the welding operation can be performed without the clamp unit 113 being in the way.

After spot welding, the swing actuator 157 is driven so that the piston rod 161 advances, and the clamp unit 113 is swung forward so as to be in the state shown by the solid line in FIGS. In this state, the clamp actuator 177 is driven,
The workpiece W is clamped and fixed by the clamp tips 181 and 183, and also in the welding gun 93, the operation of the gun pressurizing cylinder 133 causes the gun arm 119 to rotate downward from a state in which the gun arm 119 is separated from the gun arm 117 and rotate. , 123 mutually clamp and fix the work W.

In the two clamp units 113, as in FIG. 1, the tips of the clamp tips 181 and 183 are spherical, and the tips of the electrode tips 121 and 123 of the welding gun 93 are also spherical. Since the work W is gripped by these three points, there is no need to change the gauge for each work as in the case of using a gauge that matches the shape of the work. It can respond flexibly and has high versatility. Further, since the welding gun 93 is used as the clamping means, the size and cost of the robot hand can be reduced as compared with the case where three dedicated clamping means are provided.

Further, in the spot welding robot hand shown in FIG. 4, the welding gun 93 is rotatable around the supporting shaft (not shown) provided with the rotary encoder 131 together with the gun pressurizing cylinder 133. As for the clamp unit 113, since the guide rod 167 can move up and down with respect to the swinging piece 149, FIG.
As shown in (2), even if the work W is bent in a crank shape, it can be gripped and has extremely high versatility.

When the workpiece W is gripped, the gripping posture is maintained by operating the brake mechanism of the rotary encoder 131 and the linear encoder 175.
This ensures that the workpiece is gripped when transported.

As shown in FIG. 8, when the posture of the gripped work W is inclined with respect to the normal horizontal state, the rotary encoder 131 and the linear encoder 175 change the inclination. By detecting and feeding back to the robot, the inclination can be corrected as shown in FIG. 9 and a horizontal state can be obtained. This is particularly effective when positioning accuracy is required, such as setting the work W on a jig.

[Brief description of the drawings]

FIG. 1 is a perspective view of a robot hand for spot welding showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an internal structure of a clamp actuator used in the robot hand of FIG.

FIG. 3 is a cross-sectional view showing a state in which a workpiece of the clamp actuator of FIG. 2 can be gripped.

FIG. 4 is a perspective view of a robot hand for spot welding showing another embodiment of the present invention.

FIG. 5 is a side view of the robot hand for spot welding of FIG. 4;

FIG. 6 is a plan view around one clamp unit in FIG. 4;

FIG. 7 is a side view showing a state in which a workpiece of another shape is being gripped by the spot welding robot hand of FIG. 4;

8 is a side view showing a state in which the work is held in an inclined state in the robot hand for spot welding of FIG. 4;

9 is a side view showing a state where the work is gripped in a regular horizontal state in the robot hand for spot welding of FIG. 4;

[Explanation of symbols]

1,91 Robot tip shaft 3,93 Spot welding gun (clamping means) 7,97 Hand base 13,113 Clamp unit (clamp) 21,23,121,123 Electrode tip (spherical holding portion) 67,181,183 Clamp tip (spherical holding portion) 131 Rotary encoder 175 Linear encoder W Work

Claims (7)

[Claims] 1. A spot welding gun is provided on a hand base attached to a tip shaft of a robot, and three clamping means for gripping a workpiece to be welded by the spot welding gun are provided. A robot hand for spot welding, wherein mutual positional relations respectively correspond to three vertexes of a triangle, and a spherical holding portion for holding and fixing the work from both sides is provided. 2. The spot welding robot hand according to claim 1, wherein one of the three clamping means is also used by a spot welding gun. 3. The two clamping means are a work holding position for holding a work, and a retreat position farther from the spot welding gun than the work holding position so as to avoid interference with the work during welding work by the spot welding gun. 3. The robot hand for spot welding according to claim 2, wherein the robot hand is movable between and. 4. The apparatus according to claim 1, wherein each of the clamping means has an equalizing mechanism individually so that a relative position with respect to another clamping means can be displaced when gripping the work. The robot hand for spot welding as described. 5. The spot welding robot hand according to claim 4, wherein each of the equalizing mechanisms has a brake mechanism for fixing a relative position with respect to another clamping means while holding the workpiece. 6. An encoder for detecting the posture of a work in a state where the work is gripped, wherein the equalizing mechanism is fixed by a brake mechanism, and the work is brought into a normal posture based on the detection data of the encoder. 6. The spot welding robot hand according to claim 5, wherein the operation of the robot is controlled. 7. A spot welding gun provided on a tip end shaft of a robot for spot welding a work, and two clamps having the spot welding gun and a spherical holding portion for holding and holding the work from both sides. A method for gripping a workpiece by a robot hand, comprising gripping the workpiece with three gripping portions located at the vertices of a triangle.