JPS60170576A - Automatic positioning system for welding parts - Google Patents

Abstract

PURPOSE:To perform automatic arc welding with high accuracy by guiding welding parts to a desired welding target position by the cooperative operation of an arc welding robot and a handling robot. CONSTITUTION:A handling robot HR sets a work W to a target position on a surface plate 21 and a welding robot WR detects the work position. When the work W is off the target position, the deviation is calculated and is fed to the control device of the HR which resets the work W to the target position. The HR releases the work W under gripping and transports the other welding part to be welded to the set work W to the mounting position on the work W already set on the plate 21 by using a gripping mechanism 25. Whether the fresh work is set in the normal position or not is detected by the sensor of the welding robot WR and if there is a deviation, the deviation is calculated and the positioning of the fresh work to be attached is performed. Tack welding by the welding robot WR is then executed.

Description

[Detailed description of the invention] The present invention is an automatic arc welding robot (hereinafter referred to as a welding robot).
An automatic positioning system for welded parts that automatically guides the welded parts to the desired welding target position by linking the robot and the handling robot that transports the welded parts to perform highly accurate automatic arc welding. It is related to.

Welding processes such as can manufacturing work can be broadly divided into board cutting (gas cutting), bevel processing, assembly, and tacking, and consist of one welding operation and one rework/finishing operation. Of all the work, the introduction of robots and automation of actual welding has progressed considerably.
Other processes, especially assembly and tacking, are currently mostly performed manually.

For example, when automatically temporarily attaching parts such as a heat dissipation fin mounting foot terminal block to a motor frame, as shown in Fig. 1, after transporting the motor body frame a to the front of the parts handling robot C using a roller converter b, , transfer device d transfers motor body 7+/-mu a to roller conveyor b.
It is taken out from there, moved to the working position of the bozishna e, and held by the positioner e. The welding robot f moves the welding robot f at this position while pressing the heat dissipating fins and other parts carried by the parts handling robot C onto the motor main body frame a fixed in a fixed position at a fixed position on the outer peripheral surface of the motor main body frame a. Temporary work is done. When the temporary welding work is completed, the component handling robot C leaves to the standby position, and the welding robot f performs the main welding.

When performing such temporary attachment work, the accuracy of the mounting position of the welded parts such as heat dissipation fins is affected by ■ positioning accuracy of the positioner ■ positioning accuracy of the parts handling robot ■ accuracy of the supply position of the parts, etc. It is necessary to extremely strictly control all the accuracy just to perform temporary attachment, and such equipment brings about a significant cost increase, making the equipment expensive and preventing automation from being achieved.

By linking with the pot, the cent position of the welded part can be guided to the desired target position for highly accurate positioning, thereby improving the positioning accuracy of peripheral equipment and the parts handling robot itself, and further improving the parts handling robot. The purpose of the present invention is to provide an automatic positioning system for welding parts that enables automatic arc welding with high mounting position accuracy even if the positioning accuracy of the welded parts supplied to the machine is rough. , a handling robot that transports the welding part to the welding position and holds and fixes the welding part at that position, a welding robot that moves according to a taught work trajectory and welds the welding part to the workpiece, and a handling robot that performs welding by the handling robot. means for transporting the part to the welding position; means for driving the welding robot to detect the current position of the welding part using a sensor installed at the tip of its wrist; and means for correcting the current position of the welding part by driving the handling robot in a direction in which the deviation is reduced. A positioning device is provided.

Next, an embodiment of the present invention using a wire earth sensing method will be described in detail with reference to the accompanying drawings starting from FIG.

Here, FIG. 2 is a perspective view showing the schematic structure and arrangement of a handling robot and a welding robot that can be used in the above embodiment of the present invention, and FIG. 3 is a block diagram of a control circuit that can be used in the above embodiment. Figure 4 is a flowchart showing the general process of tacking work, No. 51! g
1(a) and (b) are flowcharts showing the working procedure of the automatic positioning system according to the above embodiment, and FIG.
) and (b) are schematic side views of the positional relationship between the workpiece and the torch, showing the work content of the same positioning system.

First, the rough work procedure for tacking will be explained with reference to FIGS. 2 and 4.

Temporary attachment work is performed on the surface plate 21 shown in Fig. 2.
A welding robot 1-W-R is placed on one side of the surface plate 21 so as to be able to move freely (in the X direction). rail 23
A handling robot H-R is suspended on a trolley 24 that runs along this guide rail, and a gripping mechanism 25 provided at the tip of the wrist of the handling robot H-H allows it to be moved near the surface plate 21. A workpiece W, which is a type of welding part, placed on the material storage area is grasped and the surface plate 21 is
Transport and cent to the top. When the handling robot H-R sets the workpiece W at the target position on the surface plate 21, it stops while gripping it, and then the welding robot (W-R) detects the workpiece position and moves the workpiece from the target position. If there is a deviation, the deviation is calculated and sent to the control device of the handling robot H-H, which drives the handling robot H-R to reset the workpiece W to the target position. Various means for detecting the workpiece position can be used, such as an eddy current sensor method or an image sensor method.
In the example described later, the welding wire is brought into contact with the workpiece,
A case will be described in which a wire grounding method is adopted in which the position of the workpiece is detected by detecting its conduction state. When the workpiece W is thus set at the normal target position, the handling robot HR releases its grip on the workpiece W and welds the other welding part, the workpiece W' ( (not shown) is transported from each workpiece storage area to the mounting position on the workpiece W that has already been placed on the surface plate 21 using the gripping mechanism 25 as described above, and this new workpiece W' The sensor of the welding robot (.)W-R detects whether or not the welding robot is centered, and if there is a deviation, the deviation is calculated to determine the position of the workpiece W' to be attached. Detection of the workpiece position and elimination of deviations thereof are performed in all necessary directions, including the X direction, Y direction, and Z direction. In this way, both works lol, lol
When the positioning of ' is completed, the handling robot H-
While continuing to hold the work W' to be attached by H, the welding robot performs temporary attachment.

Next, the above handling robot H-R and welding robot, 7)
The WR signal system will be explained with reference to FIG. In FIG. 3, 1 is a large workpiece such as a motor body frame, 1' is a small workpiece attached to the large workpiece 1, and the large workpiece 1 is positioned at the upper part of the surface plate 21 at -1
This shows the state set to . The example shown in FIG. 3 shows a state in which tack welding is performed on a fillet groove-shaped weld between a large workpiece 1 and a small workpiece 1', but the present invention is of course applicable to various other applications. Applicable to grooves.

3 is a torch drive mechanism, and a predetermined arm 3.3 of the handling robot H-R. A welding torch 4 is held via a wrist mechanism 3 and a wrist mechanism 3. This torch drive mechanism 3 includes a torch 4
can be moved along the melting direction of the welding target (in the case shown, the direction perpendicular to the plane of the paper, which is the X direction), and in the horizontal direction in any plane orthogonal to the welding line direction It can be freely moved in the Y and vertical directions.

The welding wire 5 is supplied to the torch 4 by means of a feeding means, for example, a feeding motor 6 which is capable of forward and reverse rotation. The feeding of the welding wire 5, the current and voltage to be applied to the wire, and the conditions necessary for welding are controlled by a welding condition setting circuit 7. A torch drive control circuit 8 controls the drive of the torch drive device 3, that is, the movement of the torch 4. This torch drive control circuit 8 stores the welding position and operation of the torch 4 in the spatial coordinate system X, Y, and Z, which have been previously taught by input or a teaching device, as digital signals. At the same time, the work program for detecting the position of the workpiece and tacking the parts that should be handled by the welding robot in the flowchart shown in Figure 5 is stored in the ROM.
-1 is stored. 9 is small work 1' of torch 4
This detection circuit detects the actual position of the welding wire 5 when the tip of the welding wire 5 comes into contact with the workpiece 1 or 1'. 10 is an arithmetic circuit, which is connected to the welding condition setting circuit 7. Torch drive control circuit 8 and detection circuit 9
．． Together with ROM-1, it constitutes a set of microcomputers.

Furthermore, the handling robot H-R has three freedoms: running the cart 24 (in the Y direction), moving in the X direction on the cart 24, and moving in the vertical direction (Z direction) by expanding and contracting the suspension arm 26 (Fig. 2). In addition to the gripping mechanism 25, the gripping operation (α direction), the swinging operation (−β direction), and the turning operation (Y
All these controls are achieved by the arithmetic unit 11, and its processing program is stored in the ROM-2.
is stored in

That is, 12X, 12y, and 12□ are motor control circuits for controlling the rotational speed of motors MX, My, and Mz, which control the transportation functions in the X direction, Y direction, and Z direction in the handling robot 1-HR, respectively. The gripping mechanism 25 is positioned by driving the motors M, , My, and M2 based on the target position signal output from the device 11. Also 12α, 12β,
12T is a motor control circuit for driving a motor Ma=Ms 1My that causes the gripping mechanism 25 to perform an opening/closing operation (α direction), a swinging operation (β direction), and a turning operation (Y direction), respectively. .

Further, the arithmetic devices 10 and 11 are synchronized by mask computers M, -C connected to a recalculation device,
Deviation information calculated in the calculation device 10 is transferred from the calculation device 10 to the calculation device 11 with or without passing through the master computer MC.

Next, using the welding robot W.R and the handling robot I].R having the above configurations, a workpiece position correction operation within the coordinate system 77 plane will be described with reference to FIGS. 5 and 6.

Here 31.32. ... indicates the number of the processing procedure (step). The following explanation is about the work of positioning and temporarily attaching the small work 1' to the large work 1 that has already been positioned at a predetermined position as shown in FIG. Regarding the positioning of the workpiece 1, wire earth sensing described later may be performed using the contact line between the surface plate 2, the large cedar tree, and the workpiece 1 as a reference, so the explanation thereof will be omitted here. First, as shown in FIG. 5(a), in steps 31 and 32, the handling robot.

(motors 12X, 12y...12
2 drive), take out the small workpiece 1' from the material storage area,
Guide it to the target cent position on the big workpiece 1. At this time, due to a positioning error of the small workpiece 1' in the material storage area, a deviation during the gripping operation by the gripping mechanism 25, and a positioning error of the handling robot, the small workpiece 1'
The cent position does not necessarily match the target cent position with high precision. This deviation is corrected in the processing from 83 onwards.

Subsequently, in steps 33 and below, the welding robot W/R is driven, and in S3. In S4, the tip of the wire 5 protruding from the torch 4 of the welding robot (W-R) is shown in FIG. 6(a) or (
Guide to the welding start point P1 as shown in b). At this time, if the workpiece is displaced in the Z direction (height direction), the positions and relationships will be as shown in Figure 6(a), and if the small workpiece 1' is displaced in the Y direction, is shown in Figure 6 (b
). Here, the wire tip point at the target set position is indicated by Pw. Next, in S5 and S6, the welding wire feed motor 6 is turned on.

Then, the tip of the welding wire 5 held by the torch 4 is let out forward from the initial position WPw. The tip of the welding wire 5 is located on the vertical surface 1a of the small workpiece 1' or on the horizontal surface I of the large workpiece 1.
When it comes into contact with either one of I, at point g, the voltage applied to the welding wire 5 is grounded to the welding object 1 or 1'. This ground is detected by a detection circuit 9. The detection circuit 9 outputs a ground detection signal to the torch drive control circuit 8. In Fig. 6(a), the contact point g is the small workpiece 1'
It is vertically offset by Xt from the welding corner where it contacts the large workpiece 1, and is also horizontally offset by 12y in FIG. 6(b). When the torch drive control circuit 8 receives the earth detection signal from the detection circuit, it issues a command to the welding condition setting circuit 7 to stop the wire feeding mortar (S7), thereby stopping the feeding of the welding wire 5.

Next, move the torch 4 vertically in the +Z direction to move the tip of the welding wire 5 from point g to point h at L2 (0,5 to 1
(within the dragon) (S8). At this time, if the detection signal of the detection circuit 9 remains ON, the initial position of the torch 4 is in the state shown in FIG. 6(a), and the detection signal is OFF.
If it becomes F, it can be determined that the initial position of the torch 4 is in the state shown in FIG. 6(b) (S9).

When the ground detection signal remains ON at point h because the workpiece is vertically displaced as shown in Figure 6(a),
Move the torch 4 horizontally in the -Y direction, move the tip of the welding wire 5 slightly by Ly (within 0.5 to 1) from point h to point i, and turn off the ground detection signal (st, o
, 311).

Next, the torch 4 is vertically lowered to move the tip of the welding wire 5 from point i toward the desired proper welding position point j. When the tip of the welding wire 5 reaches point j, the detection circuit 9 is turned on (S12, 513). The torch drive control circuit 8 stops the movement of the torch 4 in response to the ground detection signal from the detection circuit 9. At this point, the torch 4 is adjusted to an appropriate position P0 suitable for welding work.

On the other hand, in S9, if the earth detection detection signal turns OFF at point h (Fig. 6(b)), the torch 4 is moved horizontally in the +Y direction, and the i'8 contact wire 5 end is moved from h toward point i. When the tip of the m-connection wire 5 reaches one point, the detection circuit 9 is turned on (S15).

The torch drive control circuit 8 stops the movement of the torch 4 in response to the ground detection signal from the detection circuit 9.

Next, the torch 4 is moved to sequentially move the tip of the welding wire 5 from point i to point 1. This movement is described in 310
．． Sll, 512. This is performed by the process of S13.

When the tip of the welding wire 5 reaches the crescent point, the position of the torch 4 is at the welding point W p suitable for the welding operation.

is set to

When the torch 4 is moved to the proper welding position P0 by the above operation, the Y-direction and Z-direction components of the wire feed amount by the wire feed motor 6 and the Y-direction and Z-direction components of the torch by the processing of 38 to S15 are determined. By integrating the movement amounts in the directions, the workpiece shift amounts in the Y direction and the Z direction are calculated. However, in the following processing procedure, the amount of deviation of the small workpiece 1', that is, the Y direction, is corrected, but for the actual tacking, it is sufficient to correct the target position on the welding robot side during work.
The explanation thereof will be omitted here.

When the deviation in the Y direction is calculated in S16, the calculation device 10 of the welding robot transfers the deviation to the calculation device 11 on the H-R side (31
7).

The processing procedure described above is a procedure for detecting only the displacement of the small workpiece 1' in the Y direction, as shown in FIG.
During actual tacking, the deviation of the small workpiece 1' occurs three-dimensionally, so in step 518, deviations in the X and Z directions other than the Y direction are detected and transferred in the necessary directions.

When all the deviations in the necessary directions have been detected and transferred in this manner, the target cent position is corrected using these deviations in S19. This correction is performed by subtracting the deviation from the taught value, which is the original target cent position.

When the target set position is corrected in this way, 320,
The handling robot HR is driven to the corrected target position in step 521, and the small workpiece 1' is positioned at the corrected new target position.When the positioning work is completed, the handling robot HR moves the small workpiece 1' to the corrected target position.
While holding the welding robot at that position, drive the welding robot (W-R) to perform temporary attachment at the new target position (322)
.

When the tack welding work for one small work is completed in this way, the same preparation and tack welding work is performed for the next small work, or the main welding work is started.

In the above explanation, the torch 4 was slightly moved upward in order to determine the direction of deviation of the initial position of the torch 4 from the proper welding position. It is also possible to distinguish between

As described above, the present invention includes a handling robot that transports a welding part to a welding position and holds and fixes the welding part at that position, and a handling robot that moves according to a taught work trajectory and welds the welding part to an object to be welded. A welding robot, a means for linking a welding part to a welding position by a handling robot, a means for driving the welding robot and detecting the current position of the welding part using a sensor provided at the tip of its wrist, It has means for calculating the deviation between the current position of the welding part and a predetermined teaching position of the handling robot, and means for correcting the current position of the welding part by driving the handling robot in a direction in which the deviation is reduced. Because this is an automatic positioning system for welding parts, even if the accuracy of the handling robot that transports the welding parts, the positioning accuracy of the transfer device, and even the gripping accuracy are low, the welding can be performed correctly. Since the parts are positioned at the target positions with high precision, temporary attachment can be carried out easily and inexpensively in the entire apparatus.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the conventional temporary attachment of the electric motor body frame, and Fig. 2 shows the schematic structure and arrangement of a handling robot and a welding port bot that can be used in the above-mentioned embodiment of the present invention. FIG. 3 is a block diagram of a control circuit that can be used in the above embodiment, FIG. 4 is a flowchart showing the general process of tacking work, and FIG.
6(a) and (b) are flowcharts showing the working procedure of the automatic positioning system according to the above embodiment, and FIGS. 6(a) and (b) are the positional relationship between the workpiece and the torch showing the working details of the same positioning system. FIG. (Explanation of symbols) 1...Large work 1'...Small work 3...Torch drive device -4...Torch 5...Welding wire 6...Welding wire feeding mower...Welding Condition setting circuit 8...Torch drive control circuit 9...Detection circuit 10...Arithmetic circuit 11...Arithmetic device 12...Motor control circuit 21...Surface plate 24
...Dolly 25...Gripping mechanism W-R...Welding robot H-R
...Handling robot M...Motor M-C...Mask computer. Applicant Kobe Steel, Ltd. Representative Patent Attorney Takeyu Honjo. (a) Figure 6 (b) 1'

Claims (1)

[Claims] (1) A handling robot that transports a welding part to a welding position and holds and fixes the welding part at that position; (2) A handling robot that moves according to a taught work trajectory and transfers the welding part to a welding target. (3) means for transporting the welding parts to the welding position using a handling robot; and (4) a means for driving the 118-touch robot and detecting the current position of the welding parts using a sensor installed at the tip of its wrist. (5) means for calculating the deviation between the current position of the welded part thus detected and a predetermined taught position of the handling robot; (6) means for operating the handling robot in a direction that reduces the deviation. An automatic positioning system for welding parts, comprising: means for driving to correct the current position of the welding parts;