JPH069742B2 - Weld line tracking method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic copying method for consumable electrode type arc welding in lap fillet welding by an arc welding robot.

[Conventional technology]

The conventional method of detecting the welding current value and performing automatic scanning in the width direction of the groove is to oscillate the torch in the width direction of the groove, perform current integration at both ends of the oscillator, and compare the current integration values. However, the oscillating center of the torch is moved to a method in which the current integral value is small so that the current integral values at both ends are made equal.

[Problems to be solved by the invention]

However, in the method of comparing the current integral values at both ends of the oscillate, in the overlap fillet welding, when there is not much wall on the upper plate side, or when the wall is more easily melted than the flange surface and there is no wall, the first As shown in the figure, when the torch 1 is displaced to the upper plate 2 side, the wire protrusion length on the upper plate 2 side is lower than the lower plate 3
Since it is longer than the wire protrusion length on the side, the integrated current value on the upper plate 2 side is smaller than the integrated current value on the lower plate 3 side, and as a result, the lower plate 3 side should be corrected originally. Since the correction direction is the upper plate direction, there is a drawback that the welding groove deviates from the welding groove line.

Then, once deviating to the upper plate 2 side, the wire length at the left end of the oscillate in FIG.
The correction direction is on the left side in FIG. 1, and it continues to be separated from the welding groove line.

The present invention has been made in view of the above problems, in lap fillet welding without adding a special control device,
The purpose is to prevent deviation to the upper plate 2 side.

[Means for solving problems]

In order to achieve the above object, the welding line tracking method of the present invention detects a deviation toward the upper plate 2 side by comparing the current integral value at both ends of the oscillate with the current integral value at the center of the oscillate, or The double frequency component is extracted and the current phase is detected to detect the shift to the upper plate 2 side, and the correction to the lower plate 3 side is made regardless of the result of the comparison of the current integrated values at both ends of the oscillate. It is intended to prevent deviation to the side of the upper plate 2 by applying.

〔Example〕

Hereinafter, the present invention will be specifically described based on the embodiments shown in the drawings.

FIG. 2 schematically shows a welding current waveform in the case of following a welding line. The current value at both ends of the oscillate is high, and the current at the center of the oscillate is smaller than the current at both ends of the oscillate.

FIG. 3 shows a welding current waveform when there is a large shift to the lower plate 3 side, and the welding current on the lower plate 3 side at both ends of the oscillate becomes even larger.

As can be seen from FIGS. 2 and 3, the current value at either end of the oscillate is always larger than the current value at the center of the oscillate.

However, when the upper plate 2 shifts and the center position of the oscillator approaches the edge of the upper plate 2, the central current of the oscillator becomes larger than both end currents of the oscillator, as shown in FIG. It has a characteristic current waveform. Therefore, when such a current waveform is obtained, the upper plate 2
Recognizing that there is a deviation to the side, the lower plate 3 side is corrected regardless of the comparison of the integrated current values at both ends. By this,
The deviation to the upper plate 2 side is prevented.

The flow of the above control is shown in FIG.

When the integrated value of the welding current at the center of the oscillate is larger than the integrated value of the welding current at both ends of the oscillate, it can be detected that the vehicle is trying to get on the upper plate 2 side.

However, depending on the joint shape, material and welding conditions of the work piece to be welded, the welding current integral value at the center of the oscillate will be It may not exceed the integrated value of welding current.

Therefore, by multiplying the welding current integral value at the oscillate center by an offset (a and b in the flow of FIG. 5) and comparing the welding current integral values at both ends of the oscillate, even if the edges are melted, It is possible to detect the riding state on the upper plate 2 side.

Then, by adjusting the set amount of the offset, it is possible to detect a state in which the offset is slightly shifted to the upper plate 2 side.

These offsets a and b are values that change depending on the welding conditions, and are values that are based on experimental results.

Next, a method of detecting the deviation toward the upper plate 2 side by the current phase during oscillating will be described.

This control flow is shown in FIG. First, a bandpass filter that passes only a frequency twice the oscillating frequency of the smoothed current waveform is used to extract twice the frequency component. The amplitude of the double frequency component is the largest when there is no deviation, and becomes smaller as the distance from the welding line increases. In this way, the amplitude changes but the phase does not change and is constant.

However, when the torch 1 shifts to the upper plate 2 side, the current phase of the double frequency component becomes 1 / due to the influence of the edge on the upper plate 2 side.
Only shift by 4.

Therefore, by detecting the change in this current phase,
It is possible to detect a state in which the user is trying to get on the upper plate 2 side. When this phase shift is detected, it is recognized that the shift is toward the upper plate 2 side, and the lower plate 3 side is corrected regardless of the comparison of the integrated current values at both ends.

This prevents deviation toward the upper plate 2 side.

〔The invention's effect〕

As described below, in the present invention, by comparing the integrated current value at both ends of the oscillate with the integrated value of the center current of the oscillate, or by extracting a frequency component twice as high as the oscillate and detecting its phase, the overlapping corners are detected. Upper plate 2 for meat welding
The deviation to the side can be detected to prevent the deviation to the upper plate 2 side.

The method of detecting the oscillated current was relatively inexpensive and there was no interference, so it was an extremely effective method, but when applied to lap fillet welding, once it deviates to the upper plate 2 side,
Since it is kept away from the welding line, its reliability has been a problem.

INDUSTRIAL APPLICABILITY The present invention makes it possible to prevent deviation to the upper plate 2 side in lap fillet welding without using an additional device, which not only improves the reliability of sensing of lap fillet welding. It also enables sensing of lap thin-wall welding of thinner plates.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the wire length at both ends of the oscillating plate when the center of the oscillating plate shifts to the upper plate side in lap fillet welding, and FIG. FIG. 4 is a welding current waveform diagram when the front line is followed, and FIG. 3 is a welding current waveform diagram when the oscillating center is largely displaced toward the lower plate side.
The figure shows the welding current waveform diagram when the center of the oscillate is slightly deviated to the top plate side. FIG. 6 is a flowchart for detecting a shift to the upper plate side by extracting a frequency twice as high as the oscillate. 1 ... Torch 2 ... Upper plate 3 ... Lower plate

Claims (2)

[Claims] 1. A welding line follow-up method in which the oscillating center of a consumable electrode type arc welding torch, which performs welding while oscillating the torch in the width direction of the groove in lap fillet welding, follows the welding line. A welding line following method, characterized in that deviation of the overlap fillet weld toward the upper plate side is prevented by comparing the integrated current value and the integrated current value of the oscillating center. 2. A welding line follow-up method in which the center of oscillation of a consumable electrode type arc welding torch is formed by welding while oscillating the torch in the width direction of the groove in lap fillet welding. A welding line tracking method, characterized in that a current component having a doubled frequency is extracted and the phase of the current is detected to prevent deviation of the overlap fillet welding to the upper plate side.