JPH04319072A - Rough profile travel control method for measure welding robot - Google Patents

Abstract

PURPOSE:To control rough profile travel in the range where groove profile control of an arc sensor system by the high-speed rotational arc welding process can be executed when a robot to perform fillet welding of a measure type member is made to travel. CONSTITUTION:The distance between the measure type member 10 and a vertical plate 12 at the welding side is detected respectively by two noncontact type distance detection sensors 40a and 40b and the relative speed of inside and outside wheels 28a and 28b of a welding carriage 2 is controlled so that the detected distance is made equal. In addition, in turning at a corner part, a point of time where the outputs of the distance detection sensors 40a and 40b in addition to the output of a turning angle detection sensor 36 are coincident with each other is determined to be completion of turning and the parallelism of the direction of the welding carriage 2 with an adjacent vertical plate 13 is kept.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a rough tracing travel control method when performing fillet welding of a square-shaped member using a square welding robot to which an arc sensor type groove tracing control method using high-speed rotating arc welding is applied. Regarding.

0002

2. Description of the Related Art When a square-shaped member is used, for example, a diaphragm is joined to the end face of a square pipe of a building member, it may be necessary to form a fillet joint on the inside of the square pipe. Fillet joints of such square-shaped members are generally difficult or impossible to weld manually, so they are automatically welded using a square welding robot. The square welding robot is equipped with a welding torch attached to a welding cart and performs automatic arc welding using a welding wire.At this time, if an arc sensor type groove tracing control method using a known high-speed rotating arc welding method is used, , high-precision automatic bevel tracing is possible (Japanese Patent Publication No. 63-39346, Japanese Patent Publication No. 62-24857)
No. 1). Here, the groove tracing control method using an arc sensor will be briefly explained with reference to FIG. 8. Fillet welding is performed while rotating the arc at high speed, and the arc voltage or welding current is detected at that time. From the waveform of the welding current, the areas SL and SR are integrated and compared for the same phase angle φ on the left and right centering on the forward point Cf of the arc's rotational position, and the axis of rotation of the arc is welded so that the difference becomes zero. This is a method of correcting the position on a line. Also,
Regarding the control in the direction of torch height, the area of the welding current waveform is integrated for each rotation of the arc, and the integrated value is controlled to be equal to a reference value. However, using only the groove tracing control method using an arc sensor, the range in which the aiming position of the welding torch can be corrected is limited, and furthermore, it is not possible to lay a traveling rail for the welding cart, so the welding cart is used to guide the welding torch to the welding line. It is necessary to follow it roughly to some extent.

[0003] Conventionally, a method for controlling rough tracing travel of such a square welding robot has been a mechanical method in which a tracing roller is attached to the welding cart and the roller is moved while being in contact with the vertical plate surface of the square shaped member. was taken. Also,
Since it is necessary to turn the welding cart by 90 degrees at the corner of the square-shaped member, the turning angle of the welding cart is usually counted using an encoder or the like.

0004

[Problems to be Solved by the Invention] However, in the conventional rough tracing travel control method as described above, the rollers get in the way when the welding cart turns, and welding spatter adheres to the rollers, making the movement slow. I had a task to do. In addition, since the rough tracing accuracy of the conventional method is poor, even if the turning angle of the welding cart is counted using an encoder, etc., the direction of the welding cart may already be slanted when it starts turning, or the wheels may slip during turning. If the pulse signal of the encoder is distorted due to noise, it will not be possible to accurately detect the turning angle, and the turning will end with the welding cart oriented diagonally relative to the next adjacent side (vertical plate). There were issues such as:

The present invention was made to solve the above-mentioned problems, and by using two non-contact type distance sensors, it is possible to move within the range where groove tracing control using a known arc sensor is possible. In addition to roughly controlling the movement,
It is an object of the present invention to provide a rough tracing travel control method for a square welding robot that can accurately determine the end point of a turning operation.

[0006]

[Means for Solving the Problems] In order to achieve the above object, a method for controlling rough tracing of a square welding robot according to the present invention applies an arc sensor type groove tracing control method using a high-speed rotating arc welding method. With the square welding robot,
In square fillet welding, which performs fillet welding of square-shaped members, non-contact distance detection sensors are installed at the front and rear of the welding cart of the robot to detect the distance from the vertical plate on the welding side of the square-shaped member. The present invention is characterized in that the relative speeds of the inner and outer running wheels of the welding cart are controlled so that the distances detected by the two distance detection sensors are equal.

[0007] Furthermore, when turning at a corner of a square-shaped member, the square welding robot is first stopped at that turning position, and then the robot is fixed at that position and turned, and at this time the turning operation is performed. The end point is defined as the time when the rotation angle of the welding cart is detected by the rotation angle detection sensor and the outputs of the two distance detection sensors coincide.

[0008]

[Operation] The square welding robot (hereinafter referred to as robot) 1 of the present invention is installed on the horizontal plate 11 of the square member 10,
It travels around this and automatically forms fillet joints 44 at the corners of the vertical plates 12, 13 and the horizontal plate 11 of the square-shaped member. Non-contact distance detection sensors 40a and 40b are attached to the front and rear of the welding cart 2 of this robot 1, and a standing plate 12 on the welding side is installed.
and each distance detection sensor 40a, 40b. While the two detected distances are equal, the welding cart 2 is run while keeping the relative speeds of the inner and outer running wheels 28a, 28b of the welding cart 2 the same. and,
For example, when the detection distance to the vertical plate 12 is large on the front side and small on the rear side, the relative speed of the outer wheels 28b is made faster than the inner wheel 28a, and the welding cart 2 is oriented parallel to the vertical plate 12. Make it. Further, when the detected distance to the vertical plate 12 is opposite to the upward direction, the relative speed of the outer wheels 28b is made slower than that of the inner wheels 28a, so that the orientation of the welding cart 2 is made parallel to the vertical plate 12. In this way, the welding cart 2 is steered within the range in which groove tracing control using the arc sensor is possible.
Rough scanning control of travel is performed with high accuracy in a non-contact manner.

Next, the turning operation of the square-shaped member 10 at the corner portion is performed as follows. First, when the robot 1 reaches its corner turning position, it stops running. This turning position can be detected by a non-contact distance detection sensor 38 provided at the front of the welding cart 2. Next, by rotating the traveling wheels 28a and 28b in opposite directions at the same speed with the welding cart 2 fixed at this turning position by the electromagnetic magnet 34 etc., the welding cart 2 is rotated around the electromagnetic magnet 34. Start turning. Welding trolley 2
The turning angle is detected by a turning angle detection sensor 36 such as an encoder. On the other hand, when outputs are obtained from each of the distance detection sensors 40a and 40b, and the detection angle of the turning angle detection sensor 36 exceeds a predetermined angle, the distance detection sensor 40
When the outputs of a and 40b match, that time is determined to be the end point of the turning operation, and the turning operation is stopped. In other words, if only the turning angle detection sensor 36 detects 90°, it may cause wheel slippage and the influence of noise on the sensor output.
Since the orientation of the welding cart 2 with respect to the next adjacent standing plate 13 cannot be accurately regulated, this turning angle detection sensor 36
By comprehensively determining the outputs of the output and the outputs of the distance detection sensors 40a and 40b, the turning end point of the welding cart 2, that is, the parallelism of the welding cart 2 with the adjacent vertical plate 13 after turning is ensured.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view showing an embodiment of a robot according to the present invention, and FIG. 2 is a front view thereof. Further, FIG. 3 is a sectional front view of the welding cart portion, and FIG. 4 is a bottom view thereof. In the figure, 1 is a robot, 2 is a welding cart, 3 is a welding torch, 4 is a welding wire, 5 is a welding line, 10 is a square-shaped member,
Horizontal board 11 and vertical board 12 arranged to surround the horizontal board 11
, 13. Note that the vertical plates corresponding to the other two sides of the horizontal plate 11 are omitted from illustration. The robot 1 is installed on a horizontal plate 11 and is connected to a fillet joint 4 of a square-shaped member 10.
4 continuously. This robot 1 includes a welding cart 2 and a welding torch 3 installed on it,
By rotating the welding torch 3 by a rotation mechanism 16, a circular motion is given to the tip of the welding wire 4, and the arc is rotated at high speed. The rotational position of the arc (Cf, R, Cr, L, see FIG. 8) with respect to the welding direction is detected by an encoder 18 provided on the rotary motor 17 of the welding torch 3. The welding torch 3 also has a Y-axis slide mechanism 20 in the torch height direction and an X-axis slide mechanism 24 in the groove width direction.
The torch aiming position is controlled by 21 is a Y-axis motor, 22 is a Y-axis ball screw, and 23 is a Y-axis slide block, and the welding torch 3 is supported by this slide block 23. 25 is the X-axis motor, 26 is the X-axis ball screw,
27 is an X-axis slide block, and a Y-axis slide mechanism 20
is supported by this slide block 27.

The welding cart 2 has a plurality of running wheels 28a, 28.
b and a plurality of ball casters 30, the running wheels 28a
, 28b are rotated by drive motors 32a and 32b, respectively, to travel. At the center of the welding cart 2 is a square-shaped member 10.
An electromagnetic magnet 34 and a solenoid 35 are provided for fixing the welding cart 2 at a turning position at the corner of the corner.At the turning position, the electromagnetic magnet 34 is lowered by the solenoid 35, and then the solenoid 35 is energized so that the electromagnetic magnet 34 The welding cart 2 is fixed, and then the drive motors 32a and 32b are driven to rotate in opposite directions at the same speed, so that the welding cart 2 is turned around the electromagnetic magnet 34 as the center of rotation. The turning angle of the welding cart 2 is detected by a turning angle detection sensor 36 using an encoder. Further, the rotation position is detected by a rotation position detection sensor 38 using a laser sensor provided at the front of the welding cart 2 in the traveling direction.

Next, non-contact distance detection sensors 40a and 40b using laser sensors are attached to the front and rear sides of one side of the welding cart 2 to detect the distance to the standing plate 12 on the welding side. Distance detection sensors 40a, 40 are installed before and after the standard distance between the standing plate 12 and the welding cart 2.
A dead zone is provided for the output of distance detection sensor 40a, 40.
Depending on whether the output of b is inside or outside this dead band,
As will be described later, the inner running wheel 28a and the outer running wheel 28
By controlling the relative speed of b, the welding cart 2 is steered so as to go straight, away from, or approach the vertical plate 12. This allows the welding cart 2 to run roughly along the welding line 5 within the range in which the groove tracing control using the rotating arc arc sensor is possible. In the figure, 42 is a control device;
3 is a welding power source.

Next, the operation of the above embodiment will be explained with reference to FIGS. 5 and 6. FIG. 5 is an explanatory diagram of the operation of this embodiment, and FIG. 6
1 is a block diagram of a control device 42 that controls welding work. Now, if welding is to start from the welding line W1 of the standing plate 12 as shown in FIG. The target position of the welding torch 3 is controlled under groove tracing control and torch height control (arc length constant control) by an arc sensor. First, the rough tracing control of traveling will be described. The distance to the standing plate 12 is detected by the distance detection sensors 40a and 40b, respectively, and the detected distance signals are input to the control device 42 via the dead zones 41a and 41b. The control device 42 has a dead zone 41 in which the outputs of the distance detection sensors 40a and 40b are both
a, 41b, it is determined that the distance between the standing plate 12 and the welding cart 2 is within the standard distance, and the rotation speed is determined for the traveling drivers 45a, 45b of the inner and outer traveling wheels 28a, 28b. The welding cart 2 is made to move straight while maintaining the position. When either one of the outputs of the distance detection sensors 40a, 40b is outside the dead zone, it is determined whether the distance is near or far, and depending on the distance of the front and rear distance detection sensors 40a, 40b, either the inner or outer running wheel 28a, By adding a constant speed to the rotational speed of 28b, the welding cart 2 is moved away from or approached the vertical plate 12. Welding cart 2 in each of the above embodiments
Table 1 shows the steering method.

[0014]

[Table 1]

By the steering method shown in Table 1, the welding cart 2 roughly follows the welding line W1, so the control device 4
2 obtains each information of the arc rotation position from the encoder 18 and the arc voltage and welding current from the arc sensor 46, and
The rotation of the axis motor 25 and the Y-axis motor 21 is controlled, the torch aiming position is controlled by the X-axis slide mechanism 24 and the Y-axis slide mechanism 20, and the groove tracing control and torch height control by the arc sensor are performed with high precision. It is possible.

Next, the welding cart 2 is temporarily stopped when it reaches the turning position at the corner C1 of the square member 10, as shown in FIG. 5(b). This turning position is detected by a non-contact turning position detection sensor 38 attached to the front part of the welding cart 2. Next, solenoid 35
The electromagnetic magnet 34 is lowered, and the welding cart 2 is fixed at that rotating position. Further, drive motors 32a, 32b
are rotated in opposite directions at the same speed, and the welding cart 2
is rotated around the electromagnetic magnet 34 ((c in Fig. 5).
)reference). This turning angle is detected by a turning angle detection sensor 36. During the turning, the turning speed of the welding cart 2 is controlled so that the welding speed is constant, and the corner C1 is welded under the groove tracing control and torch height control using the arc sensor. Then, the turning angle is counted by the counter 48, and when the outputs of the distance detection sensors 40a and 40b match as shown in FIG. ),
If this point B is determined to be the turning end point and the turning is stopped, the direction of the welding cart 2 will always be parallel to the next standing plate 13 (
(See FIG. 5(d)). Thereafter, the electromagnetic magnet 34 is de-energized and raised, and the welding cart 2 is run in rough tracing along the welding line W2 of the standing plate 13 using the above procedure again, while groove tracing control and torch height control are performed using the arc sensor. ,
Weld the welding line W2. Thereafter, in the same manner, corner part C2
, weld line W3, corner C3, weld line W4, and corner C4 in order and return to the welding start position (Fig. 5
(see (e)).

[0017]

As described above, according to the present invention, when a robot performs fillet welding of a square-shaped member, two non-contact distance detection sensors move the welding cart between the welding-side vertical plate and the robot. Since the steering is done almost in parallel, it is possible to roughly control the travel within the range in which groove tracing control using the arc sensor method using high-speed rotating arc welding is possible, and a high-quality fillet joint can be obtained.

In addition, the end point of the turning operation at the corner of the square-shaped member is determined at the point when the outputs of the two distance detecting sensors match in addition to the output of the turning angle detecting sensor. It is possible to determine the end of the rotation, and also to keep the direction of the welding carriage parallel to the adjacent vertical plate of the grid-shaped member.

[Brief explanation of drawings]

FIG. 1 is a plan view of a square welding robot that implements the method of the present invention.

FIG. 2 is a front view of FIG. 1.

FIG. 3 is a cross-sectional front view of the welding truck portion of FIG. 1;

FIG. 4 is a bottom view of FIG. 3;

FIG. 5 is an explanatory diagram showing the operation of the robot.

FIG. 6 is a block diagram of a welding control device.

FIG. 7 is an output diagram of a distance detection sensor when the welding cart is turned.

FIG. 8 is a principle diagram of a conventional arc sensor.

[Explanation of symbols]

1 square welding robot 2 Welding trolley 3 Welding torch 4 Welding wire 5 Welding line 10 square shaped parts 11 Horizontal board 12,13 Standing board 16 Rotation mechanism 18 Encoder 20 Y-axis slide mechanism 24 X-axis slide mechanism 28a Inner running wheel 28b Outside running wheel 34 Electromagnetic magnet 36 Turning angle detection sensor 38 Turning position detection sensor 40a, 40b Distance detection sensor 42 Control device 46 Arc sensor

Claims (2)

[Claims] [Claim 1] In square fillet welding, in which fillet welding of a square-shaped member is performed by a square welding robot to which an arc sensor type groove tracing control method using high-speed rotating arc welding is applied, a welding cart of the square welding robot is used. Non-contact distance detection sensors are installed before and after the grid, and these two distance detection sensors detect the distance between the square-shaped member and the standing plate on the welding side. A rough tracing travel control method for a square welding robot, characterized by controlling the relative speed of inner and outer traveling wheels of a welding cart. 2. When the square welding robot is stopped at a turning position at a corner of a square-shaped member, and then the welding cart of the robot is rotated with the robot fixed at the turning position, the turning angle of the welding cart is changed. 2. The rough tracing travel control method for a square welding robot according to claim 1, wherein the turning operation is detected by a turning angle detection sensor and the turning operation is stopped when the outputs of the two distance detection sensors match.