JPH04228268A - Method for teaching welding robot - Google Patents

Abstract

PURPOSE:To enable a welding robot to apply high speed rotation arc welding method by deciding referential position of an arc sensor (1) in the case of fixing a torch and shifting a work, (2) in the case of shifting the torch together with the work and (3) at the time of varying relative welding direction in the case of shifting the torch together with the work. CONSTITUTION:At a starting point A of the welding, the direction of a front point Cf at arc rotating point is made to a tangential direction of the welding line 2 and teached to reverse direction to the shifting direction of a work 1. Further, from difference between the shifting vector per unit time of the welding torch 4 and the shifting vector per unit time of the work, the direction of Cf is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a teaching method for a welding robot that utilizes high-speed rotating arc welding and has a groove tracing control function using an arc sensor.

0002

BACKGROUND OF THE INVENTION Welding robots using high-speed rotating arc welding employ a groove tracing control method using an arc sensor to automatically follow the weld line. This groove tracing control method is known in Japanese Patent Application Laid-Open No. 62-248571, etc., and will be explained with reference to FIG. 9. The same phase angle φ (5
The area of the arc voltage waveform is integrated (SL, SR) within the range (°≦φ≦90°), and the torch position shift in the groove width direction (X-axis) is adjusted so that the difference (SL - SR) becomes zero. This is to correct. Further, in the torch height direction (Y-axis), control is performed so that the area of the welding current waveform is constant for each rotation of the arc. In other words, it is arc length constant control.

Therefore, in the groove tracing control method using the arc sensor described above, the position and direction of the Cf point are the basis of control. However, once this is given, the positional deviation of the welding torch is automatically corrected and a copying operation is performed.

In normal arc welding, the workpiece is fixed and only the welding torch moves, so as shown in FIG.
is determined, and a copying operation is performed with a direction X perpendicular to this welding progress direction C and the torch direction Y as the copying direction. therefore,
Since the direction of the Cf point coincides with the direction in which the robot moves the welding torch 4, the direction of the Cf point can be managed by the robot controller.

[0005]

[Problems to be Solved by the Invention] However, in the following three cases, the direction of the Cf point is unknown, so in order to use the groove tracing control method using an arc sensor, the direction of the Cf point must be determined by the robot controller in some way. need to be taught.

(1) When the welding torch is fixed and the workpiece is moved, the relative welding direction will be constant if the moving speed of the workpiece is constant. This is the case, for example, in circumferential welding of pipes.

(2) A case in which both the welding torch and the workpiece move, and the relative welding direction is constant. For example, this applies to spiral welding of pipes.

(3) A case where both the welding torch and the workpiece move and the relative welding direction changes. Examples include butt welding of square pipes and section steel, and lap welding of corrugated panels supported on carts.

[0009] The present invention has been made to solve these problems, and makes it possible to apply high-speed rotating arc welding to welding robots even in the three cases mentioned above.
An object of the present invention is to provide a teaching method for determining the direction of a reference position Cf of an arc sensor when performing groove tracing control using an arc sensor.

0010

[Means for Solving the Problems] In order to achieve the above object, a welding robot teaching method according to the present invention includes the following steps:
In a teaching method for a welding robot that uses high-speed rotating arc welding and has a groove tracing control function using an arc sensor, at the welding start point, the direction of the forward point Cf of the arc rotation position, which is the reference of the arc sensor, is set to the weld line. The object is taught in the tangential direction and in the opposite direction to the moving direction of the workpiece.

In particular, when both the welding torch and the workpiece move, the direction of the Cf point is determined by the difference vcf between the movement vector vT of the welding torch per unit time and the movement vector vW of the workpiece per unit time. = vT −
It is calculated from vW, and the direction of vcf is taken as the direction of point Cf. Of course, the direction of the Cf point in this case is the tangential direction of the weld line.

0012

[Operation] By setting the direction of the Cf point at the welding start point in the tangential direction of the welding line and in the opposite direction to the moving direction of the workpiece, the arc sensor can be used even when the welding torch of the welding robot is fixed and only the workpiece moves. This enables groove tracing control. The direction of the Cf point only needs to be given at the welding start point, and thereafter the tracing operation is performed by the automatic tracking function of the arc sensor. Therefore, it is not necessary to teach the welding end point, and it is sufficient to simply instruct the welding length.

If both the welding torch and the workpiece move at the start of welding, the tangential direction of the welding line may not be constant, so in this case, the workpiece movement information (direction, speed) is obtained and the relative Calculate the direction of travel.

[0014] The teaching method of the present invention is online;
This can be done offline.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 correspond to a case where a welding torch is fixed and a workpiece is moved. Figures 1 and 2 show circumferential welding of a cylindrical member 1a and a circular flange 1b.
This is a case where fillet welding is performed on a workpiece 1 consisting of: The weld line 2 is circular. The workpiece 1 is supported on a rotary positioner 3, and is welded by a welding torch 4 fixed at a predetermined position while rotating at a constant speed. The welding torch 4 is attached to the tip of the wrist of the robot 5 via a rotating device 6, and is rotated at high speed by a motor 7. 8 is a welding wire.

Methods for obtaining a rotating arc include an eccentric tip method (Japanese Patent Publication No. 63-39346) and an eccentric rotating mechanism method (Japanese Patent Publication No. 104684/1984). The eccentric tip method is a method in which an eccentric tip is provided at the tip of the welding torch 4 to feed power to the welding wire 8, and the tip of the welding wire 8 is fed so that the tip is eccentric from the torch axis. The eccentric rotation mechanism method is a method in which the welding torch 4 is rotated in a conical motion by an eccentric rotation gear mechanism.

Furthermore, since the welding torch 4 uses the groove tracing control method using the aforementioned arc sensor, it is configured to be movable in the groove width direction (X-axis) and the torch height direction (Y-axis). Movement of the X-axis and Y-axis can be controlled by the movement of the arm 9, but the rotating device 6 may be provided with a mechanism for moving these.

An example of the configuration of the robot 5 is shown in FIG. This robot 5 is an example of a multi-joint welding robot,
The robot body is not limited to this.

In the case of welding shown in FIG. 1, the welding torch 4 is fixed and only the workpiece 1 rotates, so the direction of the Cf point (see FIG. 9) required for groove tracing control using the arc sensor cannot be determined. The reason for this is that the welding start point and welding end point are at the same location, so the direction of welding progress cannot be determined. Therefore, as shown in FIG. 2, a tangent 21 that touches the welding line 2 at the welding start point A is found, and an auxiliary point E is located at an arbitrary position on the tangent 21 in the opposite direction to the rotational direction D of the workpiece 1.
By finding this auxiliary point E and teaching it, C
Let f be the direction of point. The auxiliary point E is used as an auxiliary point during online teaching, in addition to the main program of the robot 5 (welding current value, voltage value, welding speed, torch rotation speed, position coordinates of the welding start point, welding length, etc. are programmed). I am creating a subprogram with only points.

[0020] As described above, the relative torch traveling direction, that is, the direction of the Cf point, can be taught to the robot controller (not shown), so that the groove tracing control using the arc sensor can be performed as before.

FIG. 3 shows the case of fillet welding of the T-shaped workpiece 1. This workpiece 1 is conveyed by a conveyor 11, and the welding line 2 formed by the lower plate 1c and the vertical plate 1d is a straight line parallel to the conveyance direction F of the conveyor 11. At this time as well, if the welding torch 4 is fixed, the direction of the Cf point cannot be determined in the same way as above, so use the same method to
Teach the direction of a point. In this case, the tangent line mentioned above coincides with the weld line 2.

Next, FIGS. 5 and 6 correspond to the case where both the welding torch and the workpiece move, and the relative welding direction is constant. FIG. 5 shows the case of spiral welding of the workpiece 1, in which fillet welding is performed between the cylindrical member 1a and the spiral blade 1e.

Work 1 rotates clockwise when viewed from above,
Welding torch 4 moves from bottom to top. Therefore, at the welding starting point A, the movement vector vT of the welding torch 4 per unit time and the movement vector vW of the workpiece 1 per unit time are calculated (however, the movement vector vT of the welding torch 4 is managed by the robot controller. Therefore, only the movement information of the workpiece 1 needs to be obtained), and by calculating the difference between these movement vectors vcf = vT - vW, the direction of the vcf is taught as the direction of the Cf point. Of course, the direction of vcf (direction of point Cf) is the weld line 2
is the tangential direction. Therefore, teaching can be performed in the same way using the auxiliary point creation method described in FIG.

In FIG. 6, the upright plate 1d of FIG. 3 is placed diagonally with respect to the lower plate 1c, and the weld line 2 is an oblique straight line making a constant angle with the conveying direction F of the conveyor 11. In this case as well, since the welding torch 4 must be moved in a direction perpendicular to the conveying direction F, the direction of the Cf point is taught in the same manner as in FIG.

Next, FIGS. 7 and 8 correspond to the case where both the welding torch and the workpiece move and the relative welding direction changes. Figure 7 shows square pipe member 1f.
Fig. 8 shows the fillet welding between the corrugated plate 1h and the lower plate 1j.

In the case of the workpiece 1 shown in FIG. 7, the circumferential speed is different between the straight portion and the corner portion of the welding line 2, and accordingly, the moving speed of the welding torch 4 is also different. Normally, when welding a straight section, the rotation of the workpiece 1 is stopped and only the welding torch 4 is moved.
When welding a corner part, both the workpiece 1 and the welding torch 4 are moved. However, the welding torch 4 is moved so that the welding speed is approximately constant in both the straight section and the corner section. The same applies to the work 1 in FIG.

For such a workpiece 1, as explained in FIG. 5, at the welding start point A, the movement vector vT of the welding torch 4 per unit time, and the movement vector vW of the workpiece 1 per unit time. The difference between vcf=vT
-vW is calculated, and the direction of the vcf is taught as the direction of the Cf point.

[0028] There are two methods, one is to send information on the movement vector vW to the robot controller in real time, and the other is to calculate the movement vectors vW, vT, and vcf using an off-line program, and either method may be used.

[0029]

As described above, according to the present invention, when performing high-speed rotating arc welding with a welding robot in the three cases mentioned above, the direction of the Cf point, which is the reference of the arc sensor, is determined, so that the groove can be adjusted by the arc sensor. Copying control becomes possible.

Furthermore, since it is only necessary to teach at the welding start point, the teaching work becomes extremely simple. Therefore, there is an advantage that the teaching method of the present invention can be applied regardless of the shape of the welding line, such as a curve, or even when the workpiece is fixed and the welding torch moves as in normal welding. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory view showing an embodiment in which the method of the present invention is applied to moving a workpiece and fixing a welding torch, and is a perspective view showing circumferential welding of a cylindrical workpiece.

FIG. 2 is an explanatory diagram for determining the direction of the Cf point on the weld line of the cylindrical workpiece in FIG. 1;

FIG. 3 is a perspective view illustrating fillet welding of a T-shaped work, which is also an explanatory diagram in the case of moving the work and fixing the welding torch.

FIG. 4 is a configuration diagram showing an example of a robot used in the present invention.

FIG. 5 is an explanatory diagram showing an embodiment in which the method of the present invention is applied to a case where the workpiece and welding torch both move (the relative welding direction is constant), and is a perspective view showing spiral welding of a cylindrical workpiece.

FIG. 6 is an explanatory diagram of a case in which the workpiece and the welding torch are both moving (the relative welding direction is constant).

FIG. 7 is an explanatory view showing an embodiment in which the method of the present invention is applied to a case where the workpiece and welding torch move together (relative welding direction changes), and is a perspective view showing fillet welding of a rectangular workpiece.

FIG. 8 is a perspective view showing fillet welding of a corrugated plate, which is an explanatory diagram in the same case where the workpiece and the welding torch move together (relative welding direction changes);

FIG. 9 is an explanatory diagram showing a groove tracing control method using a conventional arc sensor.

FIG. 10 is an explanatory diagram for determining the direction of the Cf point in conventional welding.

[Explanation of symbols]

1 Work 2 Welding line 4 Welding torch 5 Robot 6 Rotating device

Claims (2)

[Claims] 1. A teaching method for a welding robot that uses a high-speed rotating arc welding method and has a groove tracing control function using an arc sensor, in which, at a welding start point, a point C in front of the arc rotation position that is a reference for the arc sensor is provided.
A teaching method for a welding robot, characterized in that the direction of f is a tangential direction of a welding line, and teaching is performed in a direction opposite to the moving direction of a workpiece. 2. Difference between the movement vector vT per unit time of the welding torch attached to the welding robot and the movement vector vW per unit time of the workpiece vcf=v
2. The welding robot teaching method according to claim 1, further comprising calculating T-vW and setting the direction of the vcf to be the direction of the Cf point.