JPH062318B2 - Welding method by welding robot - Google Patents

Description

The present invention relates to a method for performing multi-layer welding by a welding robot while operating a positioner.

The welding robot includes a robot body 1 and a robot controller 2 as illustrated in FIG.
Each axis (X, Y, Z, S, B) of (1) is programmed by the control device 2 to move the welding torch 3. The welding power source 4 sets a welding current and a welding voltage for the welding wire 5 based on a command from the robot controller 2.

On the other hand, the positioner for positioning the work with respect to the robot main body 1 is a positioner main body 6 as illustrated in the figure, and a positioner control device for controlling the drive sources 8, 8 '(servo motor etc.) of the positioner main body 6. 9 and
A disk-shaped support tool 10 arranged on the positioner body 6,
11 serves to clamp and rotate the work to position the work. The positioner body 6 has a uniaxial structure, but a multiaxial structure may be used depending on the shape of the work.

The above-mentioned robot is automatically operated after teaching, but the following welding line tracking control (copying control) is executed.

That is, when welding is performed in the manner shown in FIG. 2 (b), for example, due to a setting error of the work 12 (joint), as shown in FIG. If the welding line 13 of 12 is displaced to the right by a, or if it is displaced to the left by a ', as shown in FIG.
Since a difference occurs in the arc current at both ends of the weaving, the current difference is detected by a so-called arc sensor to obtain the magnitude and direction of the deviation, and the position of the torch 3 is corrected in the direction in which the deviation disappears. As a result, the torch 3 is moved along the welding line.

Further, in the case where welding is performed in the manner shown in FIG. 3 (a) based on the teaching data, the work 12
Assuming that the height of the welding line 13 of FIG. 1 is shifted in the Z-axis direction by the height b as shown in FIG. 6B due to the setting deviation of the work, the welding current increases and the current and the preset welding current A current deviation corresponding to the magnitude of the deviation is generated between them.
Therefore, the current deviation is obtained by the arc sensor and the torch 3 is moved in the Z-axis direction by the distance b as shown in FIG.

By the way, by the positioner body 6, for example, the fourth
When the cylindrical work 14 as shown in the figure is fixedly supported and the circumferential welding line 15 is welded by the robot, it is difficult to weld a part of the welding line 15 due to the mechanical limitation of the robot. Becomes Therefore, conventionally, a method of rotating the support tools 10 and 11 of the positioner main body with the torch 3 of the robot being fixed at the welding line position has been implemented, but the following problems occur in the implementation. Was there.

That is, the conventional welding robot program is the torch 3
Is designed to perform the welding follow-up control based on the arc sensor only when is moved along the movement trajectory during teaching. Therefore, the above method was carried out in a state without the above-mentioned welding line follow-up control, that is, in a state in which the position of the torch 3 was invariable, and therefore high quality welding results were not obtained. Therefore, the applicant of the present invention proposed, as a prior application, a method in which welding is performed by rotating the positioner under the condition that the welding robot is provided with the welding line tracking control, thereby solving the problem.

The present invention intends to provide a welding method by a welding robot capable of performing favorable multi-layer welding while operating a positioner by utilizing the method according to this prior application.

In the present invention, in order to achieve this object, after positioning the torch at the welding start position of the work, the positioner is operated to perform welding in a state where the welding line tracking function is provided to the robot, and The following trajectory of the torch during welding is stored in the memory means, and the stored content of the memory means is used for position control of the torch during multi-layer welding.

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

In the case where the welding line 15 of the work 14 shown in FIG. 4 is subjected to the multi-layer welding while rotating the support tools 10 and 11 of the positioner main body 6, the robot control program according to the fifth embodiment of the present invention is used.
It is created as illustrated in the figure.

If such a program is created, the robot controller 2 shown in FIG. 1 outputs a command to the robot body 2 and the positioner controller 9 in accordance with the contents of the robot language shown in the program, Thereby, the multi-layer welding of the welding line 15 is performed in the manner described below.

That is, first, the torch 3 is positioned at the welding start position P105 pre-teached as shown in FIG. 6 (a) in accordance with the instruction of the line number (1) of the above program. Then, in accordance with the command SARC (start arc) in line number (2), an arc is emitted from the tip of the torch 3 as shown in FIG. 2 (b), and then in accordance with the command in line number (3) as shown in FIG. The rotation direction A of the rotation shaft of the positioner main body 9 and the rotation speed B of the rotation shaft, that is, the rotation direction of the support tool 11 and its rotation speed are set.

Then, the flow of the program is shifted to the line number (10) according to the command of the line number (4), and the command of this line number (10) is executed. That is, the positioner is rotated at a specified axis rotation speed at a pre-teaching was toward the rotational position A _n (3) instruction, and the weld line tracking control by the arc sensor is performed.

As a result, as shown in FIG. 6 (c), the torch 3 welds the welding line 15 at the rotational speed of the positioner while weaving, and the torch 3 always has its weaving center directed toward the welding line 15 by the follow-up control. The position is corrected as described above. Further, since the command "PMEMO" (position storage) is written in the line number (4), the following trajectory of the torch 3 is stored in the memory in the robot controller 2 during this welding. The command "SENCE" in the line number (10) indicates that the welding line follow-up control is performed.

When the positioner rotates to the point A _n shown in FIG. 6 (d), the program flow shifts to the line number (5) and the command EA is issued.
RC (End Arc) is executed. That is, the arc emission is stopped and the welding of the first layer is completed.

Next, before the program content of line number (6) is executed, the process of positioning the tip of the torch 3 at the position P105 'shown in FIG. 7 is executed. The position P105 'is a position obtained by shifting the position P105 of the torch 3 at the start of the welding of the first layer by the distances l ₁ and l _{2 in} the longitudinal direction and the radial direction of the work 14, and this position is preset. It After completing the movement of the torch 3, line number (6)
Command SARC (start arc) is executed, the arc is emitted from the torch 3, and then the command in line number (7) is executed to rotate the positioner in the rotational direction A ′ and the rotational speed B ′.
Is newly set. In the case of this embodiment, the rotation direction A'is the same as the rotation direction A at the time of the first layer welding, but the rotation speed can be changed to a speed suitable for the second layer welding (B ≠ B '). is there.

Then, the command of the line number (8) shifts the program flow to the line number (10), and the command of the same number rotates the positioner to start the welding of the second layer. By the way, the instruction of the line number (10) is modified by the instruction PLAY of the line number (8). This command PLAY suggests that the position of the torch 3 is controlled by using the follow-up trajectory of the torch 3 stored in the memory at the time of welding the first layer. The torch 3 is controlled by the position data obtained by adding the shift amounts l ₁ and l ₂ shown in FIG. 7 (a) to the contents of the memory.

Under the PLAY command, the welding line follow-up control by the arc sensor is not performed. Further, the weaving width of the torch, the weaving period, etc. during the welding of the second layer can be specified by software. Further, An'shown in the line number (8) means that the final rotation position An of the positioner in the first layer is changed. If n = n ', the rotation positions An and 2 of the positioner in the first layer are changed. It becomes the same as that in the layer.

When the positioner is rotated to the position An'by the command of the line number (10), the command of (9) is executed to stop the arc emission, and the welding of the second layer is completed at this point.

Depending on the type of work, three-layer welding as shown in FIG. 7 (b) may be performed, but in this case as well, it can be carried out in the same manner as the second layer.

As described above, in the present invention, the welding of the first layer is performed while causing the robot to perform the welding line tracking control. While the welding of the first layer is being performed, the following trajectory of the torch is stored in the memory means, and the stored contents of this memory means are used for the position control of the torch during the multi-layer welding. Therefore, according to the present invention, it is possible to obtain a good quality multi-layer welding result without the positional deviation between the torch and the welding line.

Of course, the present invention is not limited to the welding of a circumferential welding line, and when the position itself has a function capable of moving in the X direction, the XY direction or the XYZ direction, the welding of a curved or straight welding line is performed. However, it is applicable.

[Brief description of drawings]

FIG. 1 is a perspective view conceptually showing an example of a welding robot and a positioner, FIGS. 2 and 3 are conceptual diagrams showing a mode of welding line tracking control by an arc sensor, and FIG. 4 is a rotation of the positioner. Fig. 5 is a perspective view showing an embodiment in which welding is performed while performing the welding, Fig. 5 is a view showing an example of a control program for carrying out the method of the present invention, and Figs. 6 (a) to (d) are the present invention. FIG. 7 is a perspective view conceptually showing an embodiment of such a method.
(a), (b) is sectional drawing which each conceptually illustrated the aspect of multi-layer welding. 1 ... Robot main body, 2 ... Robot control device, 3 ... Welding torch, 9 ... Positioner main body, 10, 11 ... Supporting tool, 12, 14 ...
Work, 15… Welding line.

Claims (1)

[Claims] 1. A welding having a welding line follow-up control function for detecting a deviation between a position of a welding torch and a welding line position of a work and correcting the position of the torch in a direction in which the deviation disappears based on the detection result. In the robot, after positioning the torch at the welding start position of the work, the positioner is operated with the robot having the welding line tracking control function to perform the first welding on the work, and A welding method by a welding robot, characterized in that the following trajectory of the torch therein is stored in a memory means and is used for position control of the torch during multi-layer welding of the stored contents of the memory means.