TWI630053B - Robot control apparatus and method for teaching offset value in multi-pass welding robot - Google Patents

Abstract

a coordinate system according to a teaching line passing through a plurality of teaching points, an axis parallel to the direction of gravity, and a reference axis Zs crossing the teaching line, and an axis orthogonal to the axis Xs along the teaching line and the reference axis Zs The calculation unit 7 calculates the non-orthogonal coordinate system Xs-Ys-Zs. By the button operation of the teacher TP, the difference between the positional posture at the first teaching point of the first welding pass and the position and posture under the corresponding teaching point of the Nth welding pass is used as an offset value, and the memory is memorized. For hard disk 5, the offset value is based on a non-orthogonal coordinate system. Thereby, the operator can intuitively understand the direction of the axis. Especially after the second welding pass, when the robot is moved to the designated position, the manual operation or the input of the offset value can be simply performed.

Description

Robot control device, and teaching method of offset value in multi-layer surfacing robot

The present invention relates to a robot control device and an offset value teaching method in a multi-layer surfacing robot using the robot control device.

As a welding method of a thick plate structure, so-called multilayer surfacing is known. In the multi-layer surfacing, a plurality of welding passes (welding operations) are repeated in the welding interval. In this case, if the teaching points of all the plurality of welding passes are taught, the amount of work will become very large. Therefore, the teaching point of teaching the first welding pass of the lowermost layer is adopted, and after the second welding pass, the offset value of the relative position between each teaching point and the teaching point of the first welding pass is input, thereby reducing Teaching the burden of work. The offset value is set based on the welding line coordinate system set at each teaching point of the first welding pass, and the position coordinate value is input.

As shown in Fig. 5, in the welding line coordinate system, the axis along the welding line is set to the X axis, the central axis of the welding torch T is set to the Z axis, and the axis orthogonal to the X axis and the Z axis is set to Y. axis. Further, in the welding line coordinate system, the axis along the welding line is set to the Z axis, and the center axis of the welding torch is set to the X axis. As described above, in the case of performing multi-layer surfacing, after the second welding pass, as the teaching point of the second welding pass for the teaching point of the first welding pass, the input is the welding line coordinate system as the reference. Offset value.

However, as can be seen from Fig. 5, there is no direct relationship between the axial direction of the welding line coordinate system and the joint shape of the workpiece W. Therefore, when the offset value is input, the ideal offset value obtained by the drawing of the joint shape or the like cannot be directly used. Therefore, it is necessary to manually perform the teaching operation from the teaching point of the first welding pass to the teaching point after the second welding pass, and the teaching points are determined by the teaching of the teaching.

In the teaching operation of moving the welding torch from the teaching point of the first welding pass to the teaching point after the second welding pass, manual operation is performed under the welding line coordinate system. However, the past welding line coordinates have been set by the axis along the welding line and the center axis of the welding torch. In this case, the axis along the axis of the weld is independent of the shape of the joint and still depends on the orientation of the torch. Therefore, it is difficult to perform a manual operation for moving the welding torch.

In Patent Document 1, a welding line coordinate system in which a Z-axis is set to an axis orthogonal to the earth (an axis parallel to the direction of gravity) is proposed on the premise that the welding line is parallel to the ground. By using the geodetic wire coordinate system proposed in Patent Document 1, the operability in the case of teaching after the second welding pass is manually increased. However, there are still the following problems.

As shown in Fig. 6(a), in the geodetic line coordinate system, the Z axis orthogonal to the earth is set as a fixed axis. Further, as shown by the dotted arrow in Fig. 6(a), the axis of the welding line along the welding torch T directed from the teaching point P1 toward the teaching point P2 is set to the X axis, and is orthogonal to the X axis and the Z axis. The axis is set to the Y axis. In the earth welding line coordinate system, since the Z-axis is set as a fixed axis in a state where the welding line is parallel to the ground, as shown in FIG. 6(b), when the workpiece W is inclined, the welding line cannot be parallel to the ground. Cause The set X axis does not match the axis along the weld line. This makes it difficult to perform manual operation of moving the welding torch or setting of an offset value.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2009-119525.

An object of the present invention is to provide a robot control device that can intuitively grasp a coordinate system based on a teaching line such as a welding line, and can easily perform a robot control device such as a manual operation of a robot. Further, an object of the present invention is to provide a teaching method in which, in a multilayer surfacing robot, when a teaching point after a second welding pass is specified by an offset value for a first welding pass, Even if the weld line is not parallel to the ground, the offset value can be easily set.

In order to achieve the above object, according to a first aspect of the present invention, a robot control device for controlling an action of a robot in response to an operation signal input by a teaching operation device is provided. The robot control device is based on a teaching line that is taught to a plurality of teaching points of the robot by operating the teaching operation device, a reference axis that intersects with an axis parallel to the direction of gravity and intersects the teaching line, and is orthogonal to the teaching line. The non-orthogonal coordinate system defined by the axis of both the axis and the reference axis controls the motion of the robot.

2‧‧‧Key input monitoring unit

3‧‧‧Teaching and Processing Department

5‧‧‧ Hard disk

7‧‧‧ coordinate system calculation department

9‧‧‧Action Control Department

10‧‧‧TP interface

11‧‧‧Interpretation Implementation Department

12‧‧‧Drive Command Department

21‧‧‧CPU

22‧‧‧ROM

23‧‧‧RAM

A‧‧‧Arc

Fc‧‧‧ control signal

Iw‧‧‧ welding current

Of‧‧‧Offset file

R‧‧‧Robot

RC‧‧‧Robot control unit

Ss‧‧‧ operation signal

T‧‧‧fusion torch

TP‧‧‧教器(Teach Pendant)

Td‧‧‧Multilayer surfacing program

Vw‧‧‧ welding voltage

W‧‧‧Workpiece

WM‧‧‧ cable delivery motor

WP‧‧‧ welding power supply

Wc‧‧‧ welding command signal

Wr‧‧ welding line

Fig. 1 is a schematic view showing the connection relationship between the robot control device of the present invention and the multilayer surfacing robot.

Fig. 2 is a block diagram showing the configuration of the robot control device of the present invention.

Figure 3 is a schematic view showing the axial direction of the welding line coordinate system.

The flowchart of Fig. 4 is a teaching sequence showing the offset values.

Figure 5 is a schematic view showing the axial direction of a conventional welding wire coordinate system.

Fig. 6 (a) and (b) are schematic views showing the axial direction of the geodetic line coordinate system.

[Formation for implementing the invention]

An embodiment of the robot control embodying the present invention will be described with reference to Figs. 1 to 4 .

As shown in FIG. 1, the robot controller RC outputs a motion control signal Mc based on the operation signal Ss from the teacher TP, and controls a servo motor incorporated in the plurality of axes of the robot R. Further, the robot controller RC outputs the welding command signal Wc to the welding power source WP at a specified time point in accordance with the operation signal Ss. When the welding command signal Wc is input to the welding power source WP, the welding power source WP supplies the welding voltage Vw and the welding current Iw to the robot R.

Further, the welding power source WP is a solenoid valve that controls a high pressure gas drum (not shown), and supplies the shielding gas to the welding torch T of the robot R. Further, the welding power source WP is supplied to the control signal Fc for driving the cable conveying motor WM of the robot R, and drives the cable conveying motor WM. The robot R moves the position of the front end of the welding torch T in response to the operation signal Ss. The welding line Wr is conveyed to the workpiece W of the work object by the inside of the welding torch T by the cable conveyance motor WM. The workpiece W is passed between the weld lines Wr The generated arc A is welded.

The Teach Pendant is a portable teaching operation device that is connected to the robot control device RC. The operator operates the teacher TP, switches the reference coordinate system of the robot R, or performs the micro-feeding operation of the robot R. In this way, the position and posture of the first welding pass of the robot R is taught, that is, a plurality of teaching points are taught. At this time, a plurality of teaching points are sequentially numbered sequentially starting from 1 in the order of step numbers. After the second welding pass, the offset value relative to the teaching point of the first welding pass is input for each welding pass. In this way, the teaching points after the second welding pass are automatically generated. The teaching material thus input is memorized in the interior of the robot control device RC as part of the multilayer build-up welding program Td. The offset value is input based on the welding line coordinate system of the present invention.

The robot controller RC performs the micro-feeding of the robot R in response to the operation signal Ss from the teacher TP, or performs the reproducing operation of the robot R according to the multi-layer stacking program Td. As shown in Fig. 2, the robot controller RC is composed of a CPU 21 as a central processing unit, a ROM 22 storing software programs and control parameters, a RAM 23 as a temporary calculation area, and a microcomputer including various memories. . The TP interface 10 is a portion that connects the robot controller RC and the teacher TP. The hard disk 5 is a non-volatile memory, and has a multi-layer stacking program Td or an offset file Of.

In the ROM 22, a software program useful for performing various processes is memorized. Further, the robot control device RC includes a key input monitoring unit 2, a teaching processing unit 3, a coordinate system calculating unit 7, an operation control unit 9, an explanation implementing unit 11, and a drive command unit. 12 processing department. The processing units perform various processes in accordance with control signals from the CPU 21. The key input monitoring unit 2 notifies and analyzes the operation signal Ss from the teaching device TP, and notifies the teaching processing unit 3 of the teaching information.

The teaching processing unit 3 is based on the teaching point notified from the button input monitoring unit 2, that is, the position and posture coordinate value of the robot R, or the basic welding line in the welding welding pass after the second welding pass. The offset value produces a multi-layer surfacing program Td. The teaching processing unit 3 stores the multilayer build-up welding program Td in the hard disk 5. As a teaching point notified from the key input monitoring unit 2, a welding start point, an intermediate point, a welding end point, and the like of the basic welding line constituting the first welding pass are listed. The offset value can also be stored in the internal data of the multi-layer overlay welding program Td. In addition, the offset value can also be memorized as the offset file Of from the inter-layer reference of the multi-layer surfacing program Td.

The coordinate system calculation unit 7 is a welding line coordinate system that calculates a reference value as an offset value. The interpretation implementing unit 11 reads the multilayer build-up welding program Td at each teaching point when the multilayer build-up welding program Td is reproduced, and analyzes the contents of the multilayer build-up welding program Td. When the robot R is driven, the interpretation implementing unit 11 outputs control information such as the type of the command or the position and posture value to the motion control unit 9. The motion control unit 9 performs a track plan or the like based on the control information. The operation control unit 9 outputs the operation control signal Mc to the robot R via the drive command unit 12.

Referring to Fig. 3, the action when the positional posture after the second welding pass is taught by the offset value after teaching the first welding pass will be described.

As shown in Fig. 3, in the welding line coordinate system of the present invention, the Zs axis is an axis parallel to the direction of gravity and parallel to the world coordinate system Z axis on the robot system. that is, The Zs shaft is a fixed shaft that does not change due to the orientation of the welding torch T or the weld line. As indicated by the dashed arrow in Fig. 3, the Xs axis is along the axis of the welding line passing through the welding torch T which is the teaching point m of the first teaching point and the teaching point m+1 of the second teaching point. In this case, if the welding direction is changed, the axial direction of the Xs axis can also be changed. The Ys axis is an axis orthogonal to the Zs axis and the Xs axis. As such, the weld line coordinates of the present invention are non-orthogonal coordinate systems. In addition, since the non-orthogonal coordinate system is used, the Zs axis is set and fixed to an axis that can be understood by anyone to be parallel to the direction of gravity, and the Xs axis is set to be along the axis of the weld line, and the Ys axis is set to The axis of the Zs axis and the Xs axis are orthogonal, and the axis direction can be intuitively understood. Thereby, the operability when the robot R is subjected to the micro-feeding can be improved.

Next, the teaching procedure of the offset value will be described with reference to the flowchart shown in FIG. 4.

As shown in FIG. 4, in the step (hereinafter referred to as St) 1, the operator determines the M teaching points by the welding path of the first welding pass of the workpiece W. After determining the teaching point, the operator performs the micro-feeding of the robot R for operating the teacher TP. Whenever the welding torch T reaches the respective teaching points on the workpiece W, the operator teaches the positional posture of the welding torch T with respect to the workpiece W. In this way, the reference welding line is taught by teaching the M teaching points of the first welding pass. At this time, at each teaching point, the operator can also input the operating conditions of the robot R or the welding conditions.

In St2, since the teaching after the second welding pass is performed, the operator selects the mode setting button for operating the teacher TP, and selects the offset value input mode.

St3~Stn+2 is the second welding in the offset value input mode The teaching of the welding pass after the pass. St3~Stn+2 is a process of repeating the first teaching point from the first welding pass to the Mth teaching point. The first teaching point, ..., the Mth teaching point is a teaching point of the order from the welding start point to the welding end point.

Hereinafter, the processing of each of the welding passes after St2 to Stn+2 as the second welding pass corresponding to the first teaching point (m=1) of the first welding pass will be described.

In St4, the operator moves the teacher TP to move the fusion torch T to the first teaching point of the first weld pass. At this time, the operator moves the fusion torch T for the low speed reproduction operation by manual operation.

In St5, the operator selects the weld line coordinate system for operating the teach pendant TP. In response to this operation, the coordinate system calculating unit 7 of the robot controller RC sets the axis parallel to the Z axis of the world coordinate system as the Zs axis of the welding line coordinate system. Next, as the Xs axis of the welding line coordinate system, the coordinate system calculating unit 7 sets a straight line passing through the first teaching point and the second teaching point. That is, as shown in FIG. 3, the coordinate system calculation unit 7 sets the straight line passing through the teaching point m and the teaching point m+1 to the Xs axis. The coordinate system calculation unit 7 calculates the Ys axis orthogonal to the Xs axis and the Zs axis. In this way, a welding line coordinate system in which the first teaching point is used as the origin is set.

Here, the welding line coordinate system is set in accordance with the setting operation of the operator. In addition, it is preferable to automatically calculate and set the welding line coordinate system at the stage where the welding torch T reaches the first teaching point of the first welding pass. In this case, since the setting operation work by the operator can be omitted, the teaching time can be shortened.

In St6, the operator operates the teacher TP to perform the micro-feeding of the robot R to move the welding torch T to the offset predetermined position of the second welding pass corresponding to the first teaching point of the first welding pass. At this time, the operator moves the welding torch T to the offset predetermined position of the second welding pass based on the welding line coordinate system set by St5.

After the welding torch T moves to the offset predetermined position of the second welding pass, the operator teaches the teaching device TP to teach the positional posture of the welding torch T. After teaching the position and posture of the welding torch T, in St7, the operator presses a memory button (not shown) of the teacher TP. Thereby, the difference between the positional posture at the first teaching point of the first welding pass and the position and posture under the corresponding teaching point of the second welding pass is used as an offset value, and is stored in the hard disk 5 The offset file Of, the offset value is based on the welding line coordinate system set in St5.

Next, in St8, the operator performs the micro-feeding operation with the same operation teacher TP as St6, and moves the welding torch T to the offset predetermined position of the third welding pass. Even at this time, the operator moves the welding torch T to the offset predetermined position of the third welding pass based on the welding line coordinate system set in St5.

After the welding torch T moves to the offset predetermined position of the third welding pass, the operator teaches the teaching device TP to teach the positional posture of the welding torch T. After teaching the positional posture of the welding torch T, at St9, the operator presses the memory button of the teacher TP. Thereby, the difference between the positional posture at the first teaching point of the first welding pass and the position and posture under the corresponding teaching point of the third welding pass is used as an offset value, and the offset of the hard disk 5 is memorized. File Of, the offset value is based on the welding line coordinate system set in St5 quasi.

Hereinafter, the second weld pass is the same as the third weld pass. In Stn, the operator moves the weld torch T to the offset predetermined position of the Nth weld pass. Even at this time, the operator moves the welding torch T to the offset predetermined position of the Nth welding pass based on the welding line coordinate system set in St5.

After the welding torch T moves to the offset position of the Nth welding pass, the second welding pass and the third welding pass are the same, and the operator operates the teacher TP to teach the position and posture of the welding torch T. After teaching the position and posture of the welding torch T, at Stn+1, the operator presses the memory button of the teacher TP. Thereby, the difference between the positional posture at the first teaching point of the first welding pass and the position and posture under the corresponding teaching point of the Nth welding pass is used as an offset value, and the offset of the hard disk 5 is memorized. The file Of, the offset value is based on the welding line coordinate system set in St5.

By the above-described series of operations, the offset values in the teaching points of the respective welding passes corresponding to the mth teaching point (m = 1) of the first welding pass are recorded in total. Next, in Stn+2, preparation for the teaching process corresponding to the next teaching point (m=2) of the first welding pass is performed, and the process returns to St3.

Returning to St3, the following operations and processing of St4~Stn+2 are repeated in the same manner. When the operation or processing of St4 to Stn+2 corresponding to the Mth teaching point of the first welding pass is completed, and when m>M is determined at St3, the series of teaching operations are ended.

In addition, when the teaching operation is completed, in order to correct the offset position of the completed teaching under each welding pass after the second welding pass, the following operations are performed. Work.

Initially, the operator moves the teacher TP to move the torch T to the offset position of the completed teaching. At this time, the operator performs the low-speed reproduction operation by manual operation, and moves the fusion torch T. In this way, the operator can confirm the position and posture of the welding torch T at each offset position.

Next, if there is an offset position to be corrected, after the robot R is jogged and the position of the welding torch T is changed, the operator presses the memory button of the teacher TP. In this manner, the difference between the positional posture at the teaching point of the first welding pass and the position and posture under the corrected teaching point is stored as an offset value in the offset file Of of the hard disk 5. Further, the offset value refers to an offset value based on the non-orthogonal coordinate system under each weld pass after the second weld pass.

As described above, according to the present invention, a non-orthogonal coordinate system including a Zs axis and a Xs axis which is a fixed axis parallel to the gravity direction and which is an axis along the teaching line can be set. Thereby, the operator can intuitively grasp the direction of the axis. Further, the coordinates of the teaching line such as the welding line can be used to manually operate or input the position and attitude coordinate values. In particular, in the case of a multilayer surfacing robot, when the teaching point after the second welding pass is specified by the offset value with respect to the first welding pass, the setting of the offset value can be easily performed.

Claims (5)

A robot control device for controlling an action of a robot in response to an operation signal input from a teaching operation device, characterized in that a teaching line taught to a plurality of teaching points of the robot by operating the teaching operation device is parallel to a gravity direction The axis is a reference axis of a fixed axis that intersects with the aforementioned teaching line and does not change due to the above-described teaching line, and a non-orthogonal alignment orthogonal to an axis along the axis of the teaching line and the axis of the reference axis The coordinate system controls the motion of the aforementioned robot. The robot control device according to claim 1, wherein the teaching line is a moving path of the welding torch attached to the robot, wherein the teaching line is a first teaching point and adjacent to the first teaching point. The second teaching point is set. The robot control device according to claim 1 or 2, wherein the robot control device further comprises a memory means for memorizing a position coordinate value in the non-orthogonal coordinate system, wherein the position coordinate value is memorized. The teaching point on the aforementioned teaching line is used as the offset value of the origin. A method for teaching an offset value in a multi-layer surfacing robot, which uses the robot control device according to claim 2, characterized in that it comprises the following steps: a first step for operating the teaching operation device, setting a first welding pass teaching line; a second step of moving the welding torch to a designated teaching point of the first welding pass by manual operation to set the non-orthogonal coordinate system; and a third step for operating the foregoing The teaching operation device uses the non-orthogonal coordinate system as a reference to make the welding torch from the designated teaching point of the first welding pass to the second welding pass And shifting the predetermined position corresponding to the welding pass; in the fourth step, after the welding torch moves to the predetermined offset position, operating the teaching operation device to teach the position and posture of the welding torch, and the first welding pass The difference between the positional posture under the teaching point and the positional attitude under the teaching point corresponding to each welding pass after the second welding pass is stored as an offset value; the offset value is based on the non-orthogonal coordinate system. The teaching method of the offset value in the multi-layer surfacing robot according to claim 4, wherein the fifth step is included, and the teaching is completed in each welding pass after the second welding pass. The welding torch at the offset position performs the correction of the position and posture; the fifth step is to move the welding torch to the offset position of the completed teaching, and the position and posture under the first welding pass teaching point and Correcting the difference between the position and posture of the teaching point after the correction as the offset value; the offset value is based on the non-orthogonal coordinate system in each welding pass after the second welding pass Offset value.