JPH07115186B2 - Welding robot teaching method - Google Patents

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, which utilizes a high-speed rotary arc welding method and has a groove tracing control function by an arc sensor.

[0002]

2. Description of the Related Art A welding robot utilizing a high-speed rotating arc welding method employs a groove tracking control method using an arc sensor for automatically following a welding line. This groove tracking control method is known in Japanese Patent Laid-Open No. 62-248571, and will be described with reference to FIG. 9. The arc voltage waveform and the arc rotation position (C _f , R, C _R , L) are detected. and, mainly C _f point in the welding direction ahead, the phase angles of the right and left same phi (5 °
In the range of ≦ φ ≦ 90 °), and integrating the area of the arc voltage waveform (S _L, S _R), the difference (S _L -S _R) is groove width direction so as to zero (X-axis) This is to correct the torch position shift. Regarding the torch height direction (Y axis),
The area of the welding current waveform is controlled to be constant for each revolution of the arc. That is, it is a constant arc length control.

Therefore, the position and direction of the point C _f is the basis of control in the groove tracking control system using the above arc sensor. However, once it is given, after that, the displacement of the welding torch is automatically corrected and the copying operation is performed.

In normal arc welding, the work is fixed and only the welding torch moves. Therefore, as shown in FIG. 10, from the welding start point A and welding end point B to the welding advancing direction C.
Then, the copying operation is performed with the direction X orthogonal to the welding advancing direction C and the torch direction Y as the copying direction. Therefore,
Direction of C _f point because coincides with the traveling direction of the welding torch 4 by the robot, it is possible to manage the direction of C _f point robot controller.

[0005]

However, since the direction of the C _f point is unknown in the following three cases, the direction of the C _f point is determined by some method in order to adopt the groove-tracing control method by the arc sensor. It is necessary to let the robot controller teach.

(1) When the welding torch is fixed and the work moves, the relative welding direction is constant if the moving speed of the work is constant at this time. For example, in the case of circumferential welding of pipes.

(2) When the welding torch and the work are both moved, the relative welding directions are constant. For example, spiral welding of pipes corresponds to this.

(3) This is a case where the welding torch and the workpiece both move, and the relative welding directions change. For example, butt welding of square pipes and shaped steels, lap welding of corrugated panels supported on a bogie, and the like.

The present invention has been made in order to solve the above-mentioned problems, and makes it possible to apply the high-speed rotating arc welding method to a welding robot even in the above three cases.
It is an object of the present invention to provide a teaching method for determining the direction of the reference position C _f point of the arc sensor when performing the groove copying control by the arc sensor.

[0010]

To achieve the above object, a teaching method for a welding robot according to the present invention comprises:
In a teaching method of a welding robot having a groove copying control function by an arc sensor using a high-speed rotating arc welding method, at a welding start point, a direction of a forward point C _f of an arc rotation position serving as a reference of the arc sensor is welded. The teaching is made in the tangential direction of the line and in the direction opposite to the movement direction of the work.

Further, particularly when both the welding torch and the work are moved, the direction of the point C _f is defined by the movement vector v _T of the welding torch per unit time and the movement vector v _W of the work per unit time. From the difference v _cf = v _T −v _W , and the direction of the v _{cf is} the direction of the C _f point. Of course, the direction of the point C _f in this case is the tangential direction of the welding line.

[0012]

[Operation] By giving the direction of the point C _f to the welding start point in the tangential direction of the welding line in the direction opposite to the movement direction of the work,
Even when the welding torch of the welding robot is fixed and only the work moves, the groove profile control by the arc sensor becomes possible. The direction of the point C _f may be given only at the welding start point, and after that, the copying operation is performed by the function of the automatic followability of the arc sensor. Therefore, it is not necessary to teach the welding end point, and it is sufficient to instruct the welding length.

When the welding torch and the work are moved at the start of welding, the tangential direction of the welding line may not be constant. In this case, the work movement information (direction and speed) is obtained and the relative information is obtained. Calculate the direction of travel.

The teaching method of the present invention is online,
It can be either offline.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 correspond to a case where a welding torch is fixed and a work is moved. 1 and 2 show the circumferential welding of a cylindrical member, which includes a cylindrical member 1a and a circular flange 1b.
This is the case where the fillet welding of the work 1 consisting of is performed. The welding line 2 is circular. The work 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 a high speed by a motor 7. 8 is a welding wire.

As a method for obtaining a rotating arc, there are an eccentric tip method (Japanese Patent Publication No. 63-39346) and an eccentric rotation mechanism method (Japanese Patent Laid-Open No. 62-104684). The eccentric tip method is a method in which an eccentric tip for supplying power to the welding wire 8 is provided at the tip of the welding torch 4 and the welding wire 8 is fed so as to be eccentric from the torch axis. The eccentric rotation mechanism method is a method in which the welding torch 4 is rotated by an eccentric rotation gear mechanism so as to perform a conical motion.

Further, since the welding torch 4 is of the groove-probe controlling method using the arc sensor described above, the groove width direction (X
Axis) and the torch height direction (Y axis), and the movement of the robot arm 9 can control the movement of the X axis and the Y axis. It may be provided.

An example of the structure of the robot 5 is shown in FIG. The robot 5 is an example of an articulated welding robot, but the robot body is not limited to this.

In the case of the welding shown in FIG. 1, since the welding torch 4 is fixed and only the work 1 rotates, the direction of the C _f point (see FIG. 9) necessary for the groove profile control by the arc sensor cannot be determined. The reason is that the welding start point and the welding end point are at the same position, and therefore the welding advancing direction cannot be obtained. Therefore, as shown in FIG. 2, a tangent line 21 contacting the welding line 2 at the welding start point A is obtained, and an auxiliary point E at an arbitrary position is obtained on the tangent line 21 in the direction opposite to the rotation direction D of the work 1, By teaching point E, C _f
The direction of the point. The auxiliary point E is assisted separately from the main program of the robot 5 (welding current value, voltage value, welding speed, torch rotation speed, position coordinate of welding start point, welding length, etc.) during online teaching. I am creating a subprogram with only points.

As described above, since the relative torch traveling direction, that is, the direction of the point C _f can be taught to the robot controller (not shown), the groove tracing control by the arc sensor can be performed as usual.

FIG. 3 shows the case of fillet welding of the T-shaped work 1. This work 1 is conveyed by the conveyor 11, and the welding line 2 formed by the lower plate 1c and the standing plate 1d is a straight line parallel to the conveying direction F of the conveyor 11. At this time as well, if the welding torch 4 is fixed, the direction of the C _f point is not determined as in the above case, so the direction of the C _f point is taught by the same method. In this case, the above tangent line coincides with the welding line 2.

Next, FIGS. 5 and 6 correspond to the case where the welding torch and the work are both moved and the relative welding directions are constant. FIG. 5 shows the case of spiral welding of the work 1, and shows the case of performing fillet welding of the cylindrical member 1a and the spiral blade 1e.

The work 1 rotates clockwise when viewed from above,
The welding torch 4 moves from the bottom to the top. Therefore, at the welding start point A, the movement vector v _T of the welding torch 4 per unit time and the movement vector v _{W of the} work 1 per unit time are obtained (however, the movement vector v _T of the welding torch 4 is the robot controller). Since only the movement information of the work 1 needs to be obtained), the difference v _cf = v _T −v _W between these movement vectors is calculated to determine the direction of v _cf of the C _f point. Teaching as a direction.
Of course, the direction of v _cf (direction of point C _f ) is the tangential direction of the welding line 2. Therefore, the teaching can be performed in the same manner by the auxiliary point creating method described with reference to FIG.

In FIG. 6, the standing plate 1d of FIG. 3 is placed obliquely with respect to the lower plate 1c, and the welding line 2 is an oblique straight line forming a constant angle with the conveying direction F of the conveyor 11. In this case as well, the welding torch 4 must move in the direction orthogonal to the carrying direction F, so the direction of the point C _f is taught by the same method as in FIG.

Next, FIG. 7 and FIG. 8 correspond to the case where the welding torch and the work are both moved and the relative welding directions are changed. FIG. 7 shows a square pipe member 1f.
FIG. 8 shows fillet welding between the square flange 1g and the square flange 1g, and FIG. 8 shows fillet welding between the corrugated plate 1h and the lower plate 1j.

In the case of the work 1 shown in FIG. 7, the peripheral speed is different between the straight line 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 part, the rotation of the work 1 is stopped and only the welding torch 4 is moved.
When welding the corner portion, both the work 1 and the welding torch 4 are moved. However, the welding torch 4 is moved so that the welding speed is substantially constant in both the straight portion and the corner portion. The same applies to the case of the work 1 in FIG.

For such a work 1, as described with reference to FIG. 5, at the welding start point A, the movement vector v _T of the welding torch 4 per unit time and the movement vector of the work 1 per unit time. Difference from v _W v _cf = v _T −v _W
Is calculated, and teaching is performed with the v _cf direction as the C _f point direction.

There are a method of sending information of the movement vector v _W to the robot controller in real time and a method of calculating the movement vectors v _W , v _T and v _cf by an off-line program, but either method is acceptable.

[0029]

As described above, according to the present invention, in performing the high-speed rotary arc welding by the welding robot in the above three cases, the direction of the C _f point, which is the reference of the arc sensor, is determined. Copy-ahead control becomes possible.

Further, since teaching is required only at the welding start point, teaching work becomes extremely simple. Therefore, there is an advantage that the teaching method of the present invention can be applied even when the welding line has any shape such as a curved line, and when the work is fixed and the welding torch is moved as in normal welding. .

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram for obtaining a direction of a C _f point on a welding line of the cylindrical work of FIG.

FIG. 3 is an explanatory view of the case where the work is moved and the welding torch is fixed, and a perspective view showing fillet welding of a T-shaped work.

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

FIG. 5 is an explanatory view showing an embodiment in which the method of the present invention is applied in the case of co-moving a work and a welding torch (relative welding directions are constant), and is a perspective view showing spiral welding of a cylindrical work.

FIG. 6 is an explanatory view of the case where the workpiece and the welding torch are moved together (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 in the case of co-movement of a work and a welding torch (relative welding direction changes), and a perspective view showing fillet welding of a square work.

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

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

FIG. 10 is an explanatory diagram for obtaining the direction of a C _f 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 using a high-speed rotary arc welding method and having a groove-tracing control function by an arc sensor, wherein at a welding start point, a front point C of an arc rotation position serving as a reference of the arc sensor. _f
Is a tangential direction of the welding line, and is taught in a direction opposite to the movement direction of the work piece. 2. A difference between a movement vector v _{T of} the welding torch attached to the welding robot per unit time and a movement vector v _W of the work per unit time v _cf = v _T −v
Calculates the _W, teaching methods welding robot according to claim 1, characterized in that the direction of the v _cf the direction of the C _f point.