JPH0698490B2 - Corner detection method in fillet welding - Google Patents

Description

TECHNICAL FIELD The present invention relates to a corner portion for detecting a dead end or a bending point of a welding line based on information from an arc sensor in fillet welding to which a rotary arc welding method is applied. Regarding the detection method of.

[Prior Art] Conventionally, in the members to be welded 11, 12 and 13 as shown in FIG. 5, a welding line 1 which becomes a dead end at an intersection point 2 of the standing plates 12 and 13.
Alternatively, when performing horizontal fillet welding on a weld line 3 or a bent weld line such as 1-2-3 with a robot or an automatic welding machine, teaching the 2 points as a dead end point or a bending point. It had to be recognized in advance. Even if point 2 is recognized during welding, the position may be displaced due to distortion during welding, member accuracy, and the like. For this reason,
For example, as shown in JP-A-64-15287, in the case of automatic fillet welding of square-shaped members, a position sensor for determining the turning position of the welding robot is required to recognize the position of the corner, and before welding. It was necessary to set the turning position for each corner.

[Problems to be Solved by the Invention] In such a conventional method, not only is the setup time enormous, but also when a positional deviation occurs due to welding distortion, member accuracy, etc. There was a problem of spending time.

On the other hand, the above-mentioned JP-A-64-15287 and JP-A-62-248571.
Japanese Unexamined Patent Publication (Kokai) publication describes a rotary arc welding method in which fillet welding is performed while rotating the arc at a high speed. Further, as shown in FIG. 6, the arc voltage or welding current is detected to detect the detected arc voltage or welding. From the current waveform, by integrating and comparing the areas S _L and S _R with respect to the same phase angle φ centered on the forward point C _f of the arc rotation position, the arc rotation axis is adjusted so that the difference becomes zero. A groove tracking control method using an arc sensor that corrects the position of the welding position on the welding line is described. This arc sensor uses the arc itself as a sensor and has a great feature in that information immediately below the arc can be used in real time. Therefore, by using the information of the arc sensor, it becomes possible to detect the corner position without using the conventional teaching method or position sensor.

The technique of the present invention was developed for this purpose, and an object of the present invention is to provide a method for detecting a corner portion in fillet welding that can detect the corner position in real time based only on the information of the arc sensor.

[Means for Solving the Problems] In order to achieve the above object, a corner portion detecting method in fillet welding according to the present invention is a fillet welding to which a rotary arc welding method is applied. Area information about the C _f point should be obtained at the same time not only for the forward point C _f of the arc rotation position but also for the backward point C _r.
When S _cf is compared with the area information S _{cr at the} point C _r, and as a result, when S _cf <S _{cr in} the case of arc voltage or S _cf > S _{cr in} the case of welding current, the The position is determined as the dead end or the bending point of the welding line.

[Operation] The principle of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing an arc voltage waveform at the rotational position (C _f , R, C _r , L points) of the rotating arc. Such a voltage waveform is obtained for each revolution of the arc.

Now, when the welding direction is taken in the direction of the arrow in the figure, when welding the middle of the welding line 1, the arc voltage becomes a peak at the points C _f and C _r as shown by the broken line 6 in the figure, and R, L It shows a symmetrical waveform with valleys at the points. In the case of welding current, the peaks and valleys have waveforms opposite to the above. Therefore, the areas S _cf and S _cr of the phase angle φ centered on the points C _f and C _r are equal to each other. The phase angle φ is within 90 °.

However, at the dead end or the bending point 2 of the welding line 1, since the wall (standing plate) 12 always exists in the front in the welding direction, when the arc approaches the wall 12, as shown by the solid line 7 in the figure, C _f
The arc voltage decreases and the welding current increases near the point. That is, S _cf <S _{cr for} arc voltage and S _cf > S _cr for welding current. As an example of a change in S _cf -S _cr as the determination parameter in the case of the arc voltage is shown in Figure 2. Practically, when approaching the wall, the torch 15 is tilted forward in order to prevent the welding torch 15 and the wall 12 from interfering with each other, and S _cf −S _{cr at} this time is as shown in FIG. Third
S _cf value of -S _cr from becoming large in the figure, because the torch is inclined toward the front, the change in S _cf -S _cr due to the influence of the front wall 12 is in the lowered value of S _cf -S _cr appear. Therefore, S _cf −S
_When the absolute value of _cr becomes equal to or larger than a certain threshold value X and becomes equal to or smaller than the threshold value X again, the position can be determined as a dead end point or a bending point 2 of the welding line 1. In this way, the corner position of the square-shaped member or the like can be detected in real time based only on the information of the arc sensor.

It should be noted that the conventional arc sensor is intended for the groove copying.
The control is based only on the information about the C _f point.

[Embodiment] FIG. 4 is a block diagram showing an embodiment of an apparatus for carrying out the corner detecting method of the present invention.

As shown in the figure, the welding wire 14 is fed to a position eccentric from the central shaft 17 by a power feeding tip 16 provided at the tip of the welding torch 15, and the welding torch 15 is driven by a motor 18 with a gear mechanism. Rotate at high speed via 19. The rotational position (C _f , R, C _r , L) signal of the welding wire 14 is detected by the encoder 20 attached to the motor 18. The welding torch 15 is supported by a robot (not shown), and the horizontal direction (x, y axes), the torch height direction (z axes), the torch angle direction (α, β axes), and the torch rotation direction (θ).
6 axis control.

The welding power source 21 is connected between the power feeding tip 16 and the horizontal plate 11 and generates a rotating arc 22 at the tip of the welding wire 14.
The arc voltage V and the welding current I are detected by the arc voltage detector 23 and the welding current detector 24, respectively, and are input to the CPU 27 via the differential amplifiers 25 and 26, respectively. 28 and 29 are an arc voltage setting device and a welding current setting device, respectively, which are an arc voltage detector 23 and a differential amplifier 2
5, and the arc voltage / welding current waveform signal from the welding current detector 24 and the differential amplifier 26, and the rotational position signal from the encoder 20 are obtained, and the groove tracking control by the arc sensor as described above is performed by the CPU 27. To do. The control circuit for this groove copying is not shown.

When the signals of the C _f point and the C _r point of the rotational position signal from the encoder 20 are input to the CPU 27, the S _cf integrator 30 and the S _cr integrator 31 _{convert the} arc voltage / welding current waveform signal from the C _f point and the C _f point.
The areas S _cf and S _cr of the phase angle φ centered on the point C _r are integrated for each revolution of the arc 22. And this integrated value S _cf
And S _cr are sent to the comparator 32, and the absolute value difference ΔS is determined by the determiner 3
When the value becomes equal to or more than the predetermined threshold value X by 3, the position is determined to be the dead end point or the bending point of the welding line. The output of the determiner 33 is fed back to the CPU 27, and the welding operation / direction is controlled based on this. In addition,
The dead end of the welding line can be found by counting the welding distance or the number of passes.

[Advantages of the Invention] As described above, according to the present invention, the dead end or the bending point of the welding line can be detected in real time based only on the information of the arc sensor in the rotary arc welding.
There is an effect that teaching before welding becomes unnecessary, setup time can be significantly shortened, and a good welding result can be obtained without causing a positional deviation due to welding distortion, member accuracy, and the like.

[Brief description of drawings]

FIG. 1 is a principle diagram of the corner detection method of the present invention, FIGS. 2 and 3 are diagrams showing changes in the area S _cf −S _cr as a judgment parameter in the present invention, and FIG. 4 is a method of the present invention. FIG. 5 is a block diagram showing an embodiment of an apparatus for carrying out the method, FIG. 5 is an explanatory view of fillet welding of a conventional crossed welded member, and FIG. 6 is a principle diagram of an arc sensor for copying a conventional groove. is there. 1,3 …… Weld line 2 …… Dead end or bending point 11 …… Welded member (horizontal plate) 12, 13 …… Welded member (standing plate) 14 …… Welding wire 15 …… Welding torch 16… … Power supply chip 18 …… Motor 20 …… Encoder 23 …… Arc voltage detector 24 …… Welding current detector 25,26 …… Differential amplifier 27 …… CPU 30 …… S _cf integrator 31 …… S _cr integration Unit 32 …… Comparator 33 …… Judger

Claims (1)

[Claims] 1. In fillet welding to which a rotary arc welding method is applied, an arc voltage or a welding current is detected, and the forward point C _f and the backward point C _r of the arc rotation position are determined from the waveform of the arc voltage or the welding current. In the case of arc voltage, the area S _cf and the area S _{cr of} a predetermined phase angle centered on each are integrated and compared.
When S _cf <S _cr , or for welding current S _cf > S _cr
The method for detecting a corner portion in fillet welding, wherein the position is set as a dead end point or a bending point of the welding line.