JP2000288742A - Calibration method of fixed welding gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily correct the deviation in the installation position of a fixed welding gun with excellent accuracy in simulation. SOLUTION: In the calibration method of a fixed welding gun, a jig 30 for calibration having at least three targets 31-33 is fitted between gun chips 11 and 12 of a fixed welding gun 10. The position of the targets 31-33 is taught by a robot tool 51, a work simulation program in which the position of these targets is taught is incorporated in a simulation device and regenerated to correct the deviation between the design position of the targets and the teaching position of the targets taught by the robot tool 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating a stationary welding gun which corrects a displacement of an installation position of the stationary welding gun.

[0002]

2. Description of the Related Art As a welding gun for performing spot welding on a work such as a panel material of an automobile body, for example, as shown in FIG. The welding gun 10 of the spot welding apparatus of the formula (1) is used.

The stationary welding gun 10 shown in FIG. 7 has a C-shaped gun arm 13.
Gun tips 11 and 12 (hereinafter, also simply referred to as tips) as welding electrodes are attached to the tips of. The chips 11 and 12 forming a pair move closer to and away from each other by the action of air pressure using, for example, an air cylinder (not shown).
It is set by this air cylinder.

At the time of welding, a welding gun 10 in which a work set on a positioning jig (not shown) is fixedly installed.
After the workpiece is moved toward
Spot welding is performed by sandwiching the sheet with a desired pressing force therebetween and supplying current in this state.

[0005]

The above-mentioned conventional stationary spot welding apparatus is often used together with an assembling jig, and its welding gun 10 is fixedly installed. In assembling, the displacement of the installation position of the welding gun 10 has not been corrected.

However, in practice, when the welding gun 10 is installed, an error in the installation position of the welding gun 10 occurs. For this reason, when the work set on the positioning jig is carried in using, for example, a robot, not only the spot welding position varies, but also an excessive space margin is required to avoid interference between the welding gun and the work. There was a problem that had to be taken.

As a solution to this problem, a gun tip 11, 1 of a welding gun 10 of an actual machine fixed and installed by a robot tool as a teaching tool (not shown).
It is conceivable to correct the position of the welding gun 10 in the simulation of the welding operation by teaching both the two end points. That is, first, the distance between the tips of the fixedly installed welding gun 10 of the actual machine is set to a predetermined fully open state, for example, and a robot tool is provided at both ends of the gun tips 11 and 12 having predetermined absolute accuracy. To teach these two points. At this time,
Measure the distance between gun tips with a caliper or the like. And
A simulation program of the welding operation by the welding gun 10 in which two points are taught is taken into a simulation device (not shown), reproduced, and a frame is created at each taught point in the simulation. The frame here is the coordinates of the tip of the tool at each teaching point.

On the other hand, the welding gun 10 previously set at the design value coordinates in the simulation is fully opened, and a frame is created at each of the design points at both ends of the gun chips 11 and 12. It should be noted that the distance between the frames at this time matches the previously measured distance between the gun chips. Then, the position of the welding gun 10 in the simulation is moved so that the frame at each teaching point and the frame at each design point overlap. By doing so, it is possible to correct the deviation between the actual installation position and the design position at both ends of the gun tips 11 and 12 of the welding gun 10.

However, even if such a stationary welding gun is calibrated, the following problems that cannot be solved have become apparent. That is, in the above-mentioned calibration method, since the installation position is adjusted at two points on the space (the two tips of the gun chips 11 and 12), the rotation direction about the axis connecting these two points (the direction of the arrow in the drawing) Cannot be corrected.
Therefore, in this method, the approach direction of the workpiece moved toward the stationary welding gun 10 cannot be adjusted, and in the worst case, the welding gun may interfere with the workpiece. .

In this method, since it is necessary to teach that a predetermined absolute accuracy is obtained, the opening degree of the gun chips 11 and 12 is determined in advance. Calibration cannot be performed unless it is in a state (for example, full open or half open), and it is necessary to check whether a predetermined distance between the gun chips has been reached during the calibration work, which is extremely inconvenient.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to accurately and easily correct the displacement of the installation position of a stationary welding gun within a simulation. It is an object of the present invention to provide a method for calibrating a stationary welding gun.

[0012]

The object of the present invention is achieved by the following means.

(1) A calibration jig having at least three targets is attached to a stationary welding gun, the position of the target is taught by a teaching tool, and a work simulation program in which the position of the target is taught is simulated. A method for calibrating a stationary welding gun, wherein the calibration is performed by taking in a device and reproducing the same, and correcting a deviation between a design position of the target and a teaching position of the target taught by the teaching tool.

(2) A step of mounting a calibration jig having at least three targets between a pair of welding electrodes which are movable toward and away from each other of the stationary welding gun, and the position of the target is set by a teaching tool. Teaching, and loading the work simulation program in which the position of the target is taught into the simulation device, and reproducing the loaded work simulation program by the simulation device,
At each teaching point of the target, a step of creating a frame on the simulation, at each design point of the target obtained in advance, a step of creating a frame on the simulation, Correcting the positional deviation in the simulation so that the frame and the frame at each of the design points overlap each other.

(3) The calibration jig includes a rod-like member sandwiched between the pair of welding electrodes, and an extension member connected to the rod-like member and extending substantially vertically from a central portion thereof. The calibration method for a stationary welding gun according to the above (2), wherein the targets are provided near both ends of the rod-shaped member and near a distal end of the distraction member.

(4) The calibration of the stationary welding gun according to the above (3), wherein the rod-shaped member is configured to be extendable and contractable, and a connecting position of the extension member with respect to the rod-shaped member is adjustable. Option.

(5) The calibration jig is sandwiched between the pair of welding electrodes such that the extension direction of the extension member substantially coincides with the opening direction of the arm of the stationary welding gun. (3) The method for calibrating a stationary welding gun according to the above (3).

(6) The stationary welding gun according to (2), wherein the position of the stationary welding gun in the simulation is moved so that the frame at each of the teaching points and the frame at each of the design points overlap. How to calibrate a welding gun.

[0019]

According to the present invention, the following effects can be obtained for each claim.

According to the first or second aspect of the present invention, it is possible to accurately correct a spatial error between the actual installation position of the stationary welding gun and the position in the simulation. Therefore, it is possible to appropriately perform the simulation of the welding operation, to increase the degree of freedom in the process design, and to reliably prevent a situation in which the stationary welding gun interferes with the work when the work is carried in, for example. Become.

Further, by attaching a calibration jig having a target to the welding gun, a predetermined positional accuracy of the target can be obtained. Even in the state of the opening degree, the calibration work can be easily performed by freely setting according to the calibration jig.

According to the third aspect of the present invention, the size of the gun and the movement stroke between the chips are different, and the C type or X
It can be easily applied to all stationary welding guns such as those having different types such as types.

According to the fourth aspect of the present invention, each target can be easily set to a desired positional relationship.

According to the fifth aspect of the present invention, by mounting the extension member on the welding gun with the extension direction constant, the position of the target with respect to the welding gun can be fixed, and more favorable calibration can be performed. Work becomes possible.

According to the sixth aspect of the present invention, there is an advantage that the work of correcting the displacement can be easily performed and the simulation of the welding work can be easily checked.

[0026]

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

FIG. 1 is a view showing a schematic configuration of an apparatus for using a method of calibrating a stationary welding gun according to an embodiment of the present invention, and FIG. 2 is a jig for calibration shown in FIG. (A) is a front view, (B)
Is a right side view thereof. Members common to those shown in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The stationary welding gun 10 shown in FIG. 1 is a welding gun of a stationary spot welding apparatus, and is installed on a base (not shown) fixed to the floor.

The welding gun 10 has a C-shaped (C-shaped) gun arm 13.
Is provided with a fixed-side gun tip 11 and a movable-side gun tip 12 which is paired with the fixed-side gun tip 11 and welds a work (not shown) such as a panel material. The movable gun tip 12 is fixed to the fixed gun tip 11.
An air cylinder (not shown) for advancing and retreating toward is mounted on the gun arm 13. It is also possible to move the two gun chips 11, 12 toward and away from each other by using a servomotor.

In the present embodiment, a calibration jig 30 is attached to a stationary welding gun 10 for use. The calibration jig 30 has three targets 31 to 33. At least three of these targets are required, but may be further added for confirmation or the like.

As shown in FIG. 2, the calibration jig 30 has a rod-shaped member 34 sandwiched between a pair of gun chips 11 and 12 and is connected to the rod-shaped member 34 so as to extend substantially vertically from the center thereof. And an extension member 35 that extends.

The rod-shaped member 34 includes a single screw shaft 36 having a male screw portion formed on the outer peripheral surface thereof, and blocks 37, 37 having female screw portions screwed to both ends of the screw shaft 36. have. These screw shaft 36 and block 37,
The screw portions 37 are formed, for example, at a pitch of 0.5 mm, and can finely adjust the distance between the blocks 37. Further, the distraction member 35 is
The cylindrical portion 38 has a through-hole in the center of which the fourth screw shaft 36 is inserted, and an arm portion 39 erected on the outer peripheral surface of the cylindrical portion 38. The fixing screws 43 are screwed inward from the outer peripheral surface of the cylindrical portion 38, and the cylindrical portion 38 is slid and moved to extend the distraction member 35.
After fine adjustment of the position of the connection with the rod member 34, the relative positions of the two can be fixed by the fixing screws 43, 43.

Concave portions 40, 40 are formed at substantially the center of the side surfaces of the blocks 37, 37 of the rod-shaped member 34, and X-shaped marking lines 41 are formed on the bottom surfaces of the concave portions 40, 40. . An X-shaped marking line 42 is also inserted near the distal end of the arm 39 of the distraction member 35. The intersections of these marking lines 41 and 42 constitute the first to third targets 31 to 33. As described above, since the bar-shaped member 34 is configured to be extendable and contractable, and the continuous position of the extension member 35 with respect to the bar-shaped member 34 is adjustable, the respective targets 31 to 33 can be easily positioned in a desired positional relationship. Can be set.

Each of the blocks 37, 3 of the rod-shaped member 34
7, a conical concave portion 43 is formed on the tip end surface. The tips of both gun tips 11 and 12 are fitted into the respective conical recesses 43 and 43 so that the calibration jig 30 is sandwiched between the gun tips 11 and 12.

Such a calibration jig 30
By using the method, it is possible to easily cope with all stationary welding guns such as those having different gun sizes and different movement strokes between chips, and those having different models such as C type and X type.

On the other hand, the targets 31 to 31 of the calibration jig 30 attached to the stationary welding gun 10 of the actual machine are used.
A robot tool 51 as a teaching tool is provided for teaching the position of the 33. This robot tool 5
1 is attached to the tip of the robot axis of the robot 50, and can take an arbitrary position and posture within a predetermined range of space.

Next, a method for calibrating a stationary welding gun will be described with reference to the flowchart of FIG.

First, a calibration jig 30 having targets 31 to 33 is provided between a pair of gun tips 11 and 12 of a stationary welding gun 10 which can move close to and away from each other.
Is mounted so that the calibration jig 30 is sandwiched (S1). At this time, the extension direction of the extension member 35 of the calibration jig 30 is set so as to substantially coincide with the opening direction of the arm 13 of the stationary welding gun 10. By attaching the extension member 35 to the welding gun 10 while keeping the extension direction of the extension member 35 constant, the position of the third target 33 with respect to the welding gun 10 can be fixed, and a better calibration operation can be performed. Become. Here, the calibration jig 30 is 3
Since the dimensions are measured by the dimension measuring device, a predetermined absolute accuracy is guaranteed.

Thereafter, the positions of the targets 31 to 33 of the calibration jig 30 are taught by the robot tool 51 (S2). Since the dimensions of the robot tool 51 have already been measured by the three-dimensional measuring device, it is not necessary to consider the error of the tool tip point.

Then, as shown in FIG.
The work simulation program in which the positions 1 to 33 are taught is taken into the simulation device 60 (S
3) The display unit 6 is reproduced by the simulation device 60 and
1 and frames F1 to F3 are created by simulation at the teaching points of the targets 31 to 33 (S4). In the simulation, the same reference numerals are given to the members as those of the actual machine.

When the installation position of the actual machine is the same as the design position set in advance in the robot simulation, these frames F1 to F3 are provided with the tip points of the gun chips 11 and 12 and the calibration jig. Although the target is created at the design position of the target 31 to 33 obtained from the position data of the 30 targets 31 to 33, it is actually created in a slightly separated space because of a deviation.

Next, as shown in FIG. 5, frames F4 to F6 are created by simulation at the respective design points of the target obtained in advance as described above (S5).

Finally, as shown in FIG. 6, the stationary welding gun 10 in the simulation is set such that the frames F1 to F3 created at the respective teaching points and the frames F4 to F6 created at the respective design points overlap. Is moved (S6).
The two-dot chain line in the drawing indicates the welding gun before the movement. Thereby, it is possible to correct the deviation of the installation position of the actual machine in the simulation. If the position of the stationary welding gun 10 is corrected by moving it in this way,
There is an advantage that the work of correcting the displacement can be easily performed, and the work simulation can be easily checked.

As described above, according to the stationary welding gun calibration method according to the present embodiment, the spatial error between the actual installation position of the stationary welding gun and the position in the simulation is specifically set within 2 mm. It is possible to accurately correct the positional deviation when the welding gun is installed. Therefore, it is possible to appropriately perform the simulation of the welding operation, to increase the degree of freedom in the process design, and to reliably prevent a situation in which the stationary welding gun interferes with the work when the work is carried in, for example. Become.

Further, by mounting the calibration jig having the target on the welding gun, a predetermined positional accuracy of the target can be obtained. Even in the state of the opening degree, the calibration work can be easily performed by freely setting according to the calibration jig.

The embodiments described above are not described to limit the present invention, and various modifications can be made by those skilled in the art within the technical concept of the present invention.

For example, in the above embodiment, the case where the calibration jig 30 is mounted so as to be sandwiched between the gun chips 11 and 12 has been described, but the present invention is not limited to such an embodiment. Instead, it is only necessary to mount the calibration jig 30 so as to obtain a predetermined accuracy. For example, the calibration jig 30 can be mounted and fixed on the gun chip 11 on the fixed side.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an apparatus for using a calibration method for a stationary welding gun according to an embodiment of the present invention.

2A is a front view, and FIG. 2B is a right side view of the calibration jig shown in FIG. 1;

FIG. 3 is a flowchart showing a method for calibrating a stationary welding gun.

FIG. 4 is a diagram showing a state in which a work simulation program in which the position of a target is taught is taken into a simulation device and reproduced, and a frame is created at each taught point.

FIG. 5 is a diagram illustrating a state in which a frame is created at each design point of a target obtained in advance.

FIG. 6 is a diagram showing a state in which the position of the stationary welding gun is moved so that a frame created at each teaching point and a frame created at each design point overlap each other.

FIG. 7 is an elevational view showing a stationary welding gun.

[Explanation of symbols]

 Reference Signs List 10: stationary welding gun, 11, 12: gun tip (welding electrode), 30: calibration jig, 31-33: target, 34: rod-shaped member, 35: extension member, 51: robot tool (teaching tool) , 60: simulation device, F1 to F6: frame.

Claims (6)

[Claims] 1. A stationary jig for mounting a calibration jig having at least three targets,
The position of the target is taught by a teaching tool, a work simulation program in which the position of the target is taught is loaded into a simulation device and played back, and the design position of the target and the teaching of the target taught by the teaching tool are taught. A method for calibrating a stationary welding gun, comprising correcting a deviation from a position. 2. A step of mounting a calibration jig having at least three targets between a pair of welding electrodes which are movable toward and away from each other of a stationary welding gun, and the position of the targets is adjusted by a teaching tool. Teaching, and loading the work simulation program in which the position of the target has been taught into the simulation device, playing back the loaded work simulation program with the simulation device, and performing each of the teaching points of the target on the simulation. A step of creating a frame, a step of creating a frame on a simulation at each design point of the target obtained in advance, and a step of overlapping the frame at each teaching point and the frame at each design point. Stain Calibration method of stationary type welding gun, characterized in that and a step of correcting the positional deviation in the configuration. 3. The calibration jig has a rod-shaped member sandwiched between the pair of welding electrodes, and an extension member connected to the rod-shaped member and extending substantially vertically from a central portion thereof. 3. The calibration method for a stationary welding gun according to claim 2, wherein the targets are provided in the vicinity of both ends of the rod-shaped member and in the vicinity of the tip of the distraction member. 4. The method for calibrating a stationary welding gun according to claim 3, wherein the rod-shaped member is configured to be extendable and contractable, and a position where the extension member is connected to the rod-shaped member is adjustable. 5. The calibration jig is sandwiched between the pair of welding electrodes such that a direction of extension of the extension member substantially coincides with an opening direction of an arm of the stationary welding gun. The method for calibrating a stationary welding gun according to claim 3, characterized in that: 6. The stationary welding gun according to claim 2, wherein a position of the stationary welding gun in a simulation is moved so that a frame at each of the teaching points and a frame at each of the design points overlap. Calibration method.