JPH0673747B2 - Grid welding robot - Google Patents

Description

TECHNICAL FIELD The present invention relates to a welding robot, and more particularly to a welding robot that performs fillet welding of a grid-shaped base material.

[Prior Art] Conventionally, in the case of fillet welding of a grid-shaped base metal, a welding robot performs welding of straight portions on each surface, and then the remaining corner portions are welded by hand welding. And so on.

[Problems to be Solved by the Invention] However, in such a conventional technique, continuous welding work cannot be performed, and it becomes difficult to maintain a good welding state when performing welding by manual welding, There was a problem that the quality could not be stabilized.

The present invention has been made in view of the above points, and an object of the present invention is to obtain a welding robot capable of achieving FA in mesh fillet welding and performing stable welding work of stable quality.

[Means for Solving Problems] The grid welding robot according to the present invention follows the welding line along the welding base metal by the two supporting means, and uses the sliding means when welding the corners of the grid type. With the support means moved, the welding head is rotated on the welding carriage to perform welding, and the arc line sensor automatically controls the welding line to solve the above problems.

[Operation] In the present invention, since the supporting means is moved by the sliding means when welding the square corner portion, there is no interference with the welding head when the welding head turns, and the corner portion is similar to the straight portion. Can perform continuous welding, and since the welding line automatic copying control is performed using the arc sensor, the welding line automatic copying control can be performed by following the swiveling operation even when the welding head is swiveling. Becomes Therefore,
FA of welding work can be easily performed and quality can be stabilized.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a mesh fillet welding robot showing an embodiment of the present invention, in which (A) is a plan view and (B) is a front view. In the figure, (10) is a grid-type welding base material, (12) is a welding carriage, and this welding carriage (12)
The traveling wheels (14) are provided at four corners of the vehicle, and the traveling motor (16) rotationally drives the traveling wheels (14) to move the welding carriage (12).

A high-speed rotating arc welding torch (18) is installed on the welding carriage (12), and the high-speed rotating arc welding torch (18) has an X-axis slide (20) and a Y-axis slide (22).
It is configured to be slidable in each direction by a swivel motor (24) and swivel driven by a swivel motor (24). The swivel angle of this high-speed rotary arc welding torch (18) can be detected by an encoder (25). Has become. The X-axis slide (20) is a mechanism for sliding the high-speed rotating arc welding torch (18) in the horizontal direction by the automatic copying control of the welding line, and the Y-axis slide (22) keeps the arc length constant. Welding torch This mechanism slides the high-speed rotating arc welding torch (18) in the axial direction.

(26) is a shield nozzle provided in the high speed rotating arc welding torch (18).

(32a) and (32b) are support shafts that are arranged in parallel to the lower end of the welding carriage (12) so as to face each other and are supported in a retractable state. A support roller (34) is rotatably supported at both ends of the (32b), and the support roller (34) performs rough copying of a welding line in a linear direction along the welding base material (10). It is like this.

FIG. 2 shows a part of the back surface of the welding carriage (12), and the support shafts (32a) and (32b) are formed with external threads on their outer peripheral portions, respectively. Bearings (36) each having an internal thread formed with an internal thread to be engaged with the external thread of 32b) are fixed below the welding carriage (12). Then, the bearing portions (36) are rotationally driven by the motors (38a) and (38b), respectively, and the support shafts (32a) and (32b) are axially screw-slide inside the bearing portions (36). It is configured to do. The positions of the support shafts (32a) and (32b) are detected by the potentiometer (40). The traveling wheels (14) and the like are omitted in order to clarify the configuration near the support shafts (32a) and (32b).

Next, the principle of the arc sensor that performs automatic welding line copying control will be briefly described.

FIG. 3 shows the relationship between the temporal arc generation position of the rotating arc and the arc voltage. In the figure, when the high-speed rotating arc welding torch (18) is in the groove route (△
X = 0), the arc voltage waveform is Cf as shown by the broken line.
It becomes maximum at points and Cr, becomes minimum at points R and L, and is symmetrical with respect to point Cf. On the other hand, high-speed rotating arc welding torch (1
When (8) shifts to the standing plate side (ΔX ≠ 0), the waveform becomes as shown by the solid line and symmetrical with respect to the Cf point. Therefore, the torch aiming position in the X-axis direction is detected by comparing the areas S _L and S _R of the waveform surrounded by the phase angle φ on the left and right of the point Cf. Actually, the value of φ is set to 90 ° or less because the waveform is distorted on the rear Cr side due to the influence of the molten material. The torch height direction (Y axis) is controlled by a method in which the welding current is constant.

Next, the overall operation of the above embodiment will be described in order of (A) to (F) in FIG. 4 with reference to the block diagram of FIG. 5 and the schematic flow chart of FIG. In addition, since the configurations of the respective drawings (A) to (F) in FIG. 4 are exactly the same, the reference numerals are allotted to (A) and (B)
About (F), only the code | symbol of the part required for description is attached. Further, the schematic flow chart of FIG. 6 shows only the 90-degree turning operation of the high-speed rotating arc welding torch (18).

First, the welding robot is arranged at an arbitrary position inside the grid-shaped welding base material (10) as shown in FIG.
As shown in the figure, extend a) and (32b) vertically to the W1 surface of the welding base metal (10), press each supporting roller (28) into pressure contact, and move the welding carriage (12) straight to the right. Start rotating arc welding.

Then, linear welding is performed along the W1 surface of the welding base material (10), and when the welding carriage (12) reaches a predetermined position as shown in FIG.

This stop position is determined in consideration of a predetermined distance from the W2 surface, that is, the turning radius of the high-speed rotating arc welding torch (18) and the maximum sliding distance of the torch (18) in the X-axis direction. As a method of detecting the distance as described above, for example, a sensor (not shown) that detects the W2 surface at a predetermined distance from the W2 surface
There is a method of detecting the stop position by. As the control operation, when the position sensor detects a predetermined position, the signal is input to the control device (44), and the control device (4
In 4), stop control of the traveling motor (16) is performed.

Next, by driving the turning motor (24), the high-speed rotating arc welding torch (18) is turned to the right while the welding carriage (12) is fixed at the predetermined position. At this time, since the support shaft (32a) interferes with the shield nozzle (26), the support shaft motor (38a) is driven to move the support shaft (32a) to the rear W3 in the axial direction as shown in FIG. Slide in the surface direction, and in this state, turn C1
Welding.

At this time, if the high-speed rotating arc welding torch (18) is simply swung, the distance between the welding torch (18) and the welding position greatly changes depending on the swivel angle. The high-speed rotating arc welding torch (18) is fed out in the horizontal axis direction. Further, in the control device (44), the welding speed, that is, the output of the turning motor (24) is controlled according to the turning angle of the high-speed rotating arc welding torch (18) detected up to the encoder (25). The welding speed control will be described later.

Next, after 90-degree turning is performed and welding near the corner C1 is completed as described above, the support shaft (32a) is slid again in the direction of the W1 surface as shown in FIG. Rotate the rotary arc welding head (18) to the right as at C1 to make it corner C2.
Welding. Next, after welding in the vicinity of the corner C2 is completed, slide both support shafts (32a) and (32b) in the direction of the W3 surface, and perform linear welding of the W3 surface in the same manner as the W1 surface described above. After that, the welding operation is advanced by the same operation. When the welding end position is detected by the action of the arc sensor, the traveling motor (16) and the arc generating power source (not shown) are stopped to complete the welding of the entire circumference of the inside of the welding base material (10).

Next, a method of controlling the welding speed at the time of welding the corner portion of the above embodiment, that is, at the time of the turning operation of the high speed rotary arc welding torch (18) will be described with reference to FIG. In the figure,
The actual welding speed along the welding base metal (10) is V _W , the turning angle of the high-speed rotating arc welding torch (18) is α, the turning radius is r,
Let V _{R be} the turning speed and V _R 1 be the speed component in the tangential direction of the turning arc of the welding speed V _W. The following two expressions hold.

Therefore, from the above equations (1) and (2), In the range of, V _R = V _W × cos ² α (3) In the range of, two formulas (3) and (4) of V _R = V _W × sin ² α (4) can be obtained.

In this embodiment, the turning angle α is set to the encoder (25) so that the welding speed V _W becomes constant based on the above equation.
The stable control is performed by the control device (44) via the.

Next, a method of detecting the end position of the welded portion will be described with reference to FIG. This method utilizes that the arc voltage drops as the distance between the welding electrode and the member to be welded decreases, and in this embodiment, the rotating arc reaches a portion where welding has already been performed. In this method, the end position of the welded portion is detected by detecting the drop in the arc voltage when the distance between the welding electrode and the welded portion becomes short.

FIG. 8 shows the relationship between the temporal arc generation position of the rotating arc and the arc voltage. In the figure, at the arc generation position of the rotating arc, the forward position in the traveling direction is C
f, the rear position is Cr, and both sides in the traveling direction are R and L. In the figure, the arc voltage when an arc is generated in a portion not yet welded is indicated by a broken line.In this embodiment, since fillet welding is performed by a rotating arc, the arc is generated by rotating. The distance between the welding electrode (28) and the welding base metal (10) is shorter at the positions R and L on both sides when compared to the front position Cf and the rear position Cr, so that the arc voltage is inevitable at R and L. Is a low value.

First, as indicated by the shaded area in the figure, integral values SCf and SCr of the arc voltage within a predetermined range between the front position Cf and the rear position Cr of the arc generation are obtained. Then, these integrated values SCf and SCr are compared with each other, and a position where SCf continuously becomes larger than SCr by a predetermined number of times is detected as a starting end position of the welding portion, that is, an ending position.

Thus, according to the above-mentioned embodiment, the grid-type welding base metal (1
When welding the corner portion of (0), the welding head (18) is rotated, and at this time, the welding head (18) and the support shaft (32a),
In order to avoid interference with (32b), the support shafts (32a), (32
While b) is screw-sliding, the arc voltage is detected by using the arc itself, and when the welding head (18) is swiveling, the welding line is automatically traced by following the swiveling operation, so welding is continued. Since the welding end position is also detected, there is an effect that FA work can be performed and quality can be stabilized.

The present invention is not limited to the above embodiment,
Various design changes can be made so as to achieve the same function.

[Effects of the Invention] According to the present invention as described above, when welding a grid-type welding base metal, the entire circumference can be continuously welded, and
Even when the welding head is swiveling, the swiveling operation can be followed to accurately control the welding conditions, facilitating the FA of the welding operation and stabilizing the quality.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIGS. 2 and 3 are configuration diagrams of main parts of the embodiment, and FIGS. 4, 5, and 6 are explanatory diagrams showing the operation of the embodiment. 7 and 8 are explanatory views showing the operation of the embodiment. “Explanation of symbols for main parts” (10) …… Welding base metal, (12) …… Welding carriage, (18) ……
High-speed rotating arc welding torch, (24) …… Swing motor,
(25) …… Encoder, (26) …… Shield nozzle,
(32a), (32b) ... support shaft, (34) ... support roller,
(36) …… Bearing part, (38a), (38b) …… Motor,
(44) …… Control device. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A welding head having a high-speed rotating arc welding torch is provided on a welding carriage that is driven by traveling drive means, and at least two supporting means are used to roughly copy the welding line and the welding line detection information of the arc sensor is provided. While performing automatic welding line copying control based on, in a welding robot for arc welding of a grid-type welding base material, position detection means for detecting a corner position of the grid-type welding base material, and the welding head A turning means for turning on the welding carriage; a sliding means for moving the supporting means so as not to interfere with the welding torch and the supporting means when turning the welding head; and a turning angle of the welding head is detected. And a control means for controlling the entire welding operation. The control means is based on information from the arc sensor. While automatically performing welding line copying; when the position detecting means detects the corner position of the grid-type welding base metal, the traveling drive means is stopped; and then the slide means causes at least one of the supporting means. Next, based on the turning angle information of the turning angle detection means, the turning speed is controlled so that the welding speed becomes a predetermined speed; when the turning angle reaches a predetermined value, the turning is stopped, and A grid welding robot characterized in that it is made to travel again by a travel drive means; the welding end position is detected based on the information of the arc sensor, and control is performed to terminate the welding operation.