JPH0839246A - Ac arc welding machine - Google Patents

Abstract

PURPOSE:To provide an AC arc welding machine capable of attaining compatibility of a cleaning effect with directivity of arcs. CONSTITUTION:A period A when the time ratio of EN (electrode minus) in one period of AC is small and the cleaning effect is high but the directivity of the arcs is weak and a period B when the time ratio of EN (electrode minus) in one period of AC is large and the cleaning effect is low but the directivity of the arcs is good are repeated alternately or at a specific ratio in AC arc welding. As a result, the range cleaned in the period A is welded with the arcs with good directivity in the period B, by which the compatibility of the cleaning with the directivity of the arc is attained and a favorable welding result is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the cleaning effect and the arc directivity of an AC arc welder.

[0002]

2. Description of the Related Art In recent years, an AC arc welding machine has been widely used, but it is a problem to make the cleaning effect compatible with the arc directivity.

A conventional AC arc welder will be described below. In a conventional AC arc welding machine, the time ratio of EN (Electrode Negative: the electrode is negative with respect to the base metal, hereinafter referred to as the electrode minus) during one cycle of alternating current was not changed and kept constant. Further, it is known that if the time ratio of EN (electrode minus) in one cycle of alternating current is reduced in order to enhance the cleaning effect, the cleaning effect is enhanced but the directivity of the arc is deteriorated.

2 (a) and 2 (b) are waveform charts showing the relationship between the time ratio of EN (electrode minus) in one AC cycle, the cleaning effect and the directivity of the arc.
FIG. 2A shows EN (minus electrode) during one cycle of alternating current.
In this case, the cleaning effect is enhanced but the directivity of the arc is deteriorated. Further, FIG. 2B shows a case where the time ratio of EN (electrode minus) in one cycle of alternating current is increased. In this case, the cleaning effect is weakened but the directivity of the arc is improved.

[0005]

In such a conventional AC arc welding machine, an AC arc welding method is used because a cleaning effect is generally required when welding aluminum, and in this case, The cleaning effect is EP (ElectrodePlus:
It is known that the greater the time ratio of the positive electrode to the base material and the positive electrode hereinafter), the stronger the material.

In conventional AC arc welding, when the time ratio of EP (electrode plus) in one cycle of AC is increased, the time ratio of EN (electrode minus) becomes smaller and the cleaning effect becomes stronger, but the arc is stronger. Has a problem in that it is not possible to weld the intended part.

Further, in order to improve the directivity of the arc, if the time ratio of EP (electrode plus) in one cycle of alternating current is decreased, the time ratio of EN (electrode minus) increases, and the arc directivity increases. However, there is a problem that the cleaning effect is weakened and the welding result is deteriorated.

The present invention solves the above problems, and an object of the present invention is to provide an AC arc welder capable of improving both the cleaning effect and the directivity of the arc.

[0009]

In order to achieve the above-mentioned object, the present invention sets AC cycle as a cycle in which the time ratio of EN (electrode minus) in one cycle of AC is small in AC arc welding. In the AC arc welding machine, the cycle with a large time ratio of EN (electrode minus) shown in 1 cycle is defined as the B cycle, and the A cycle and the B cycle are alternately output at a ratio of 1: 1 or other. is there.

[0010]

According to the present invention, in the above configuration, the A cycle in which the time ratio of EN (electrode minus) in one cycle of AC is small and the B cycle in which the time ratio of EN (electrode minus) in one cycle of AC is large. By alternately outputting
The cleaning effect is maintained in the A cycle where the N (electrode minus) time ratio is small, and the arc directivity is maintained in the B cycle where the EN (electrode minus) time ratio is large, so that the cleaning effect and the arc directivity are satisfied at the same time. To work.

[0011]

The operation of the AC arc welding machine of the present invention will be described below with reference to the drawings. FIG. 1 is a waveform diagram showing an AC current waveform in this embodiment. Figure 1 (a)
The alternating current waveform when the cleaning effect is strengthened is shown. In the figure, cycle A is a case where the time ratio of EN (electrode minus) in one cycle of alternating current is small, and the cleaning effect is enhanced but the directivity of the arc is weakened. The next B cycle is a case where the time ratio of EN (electrode minus) in one cycle of AC is increased, and the cleaning effect is weak, but the directivity of the arc is good. A distance corresponding to the welding speed and the frequency of the alternating current exists between the place where the A-cycle arc is generated and the place where the B-cycle arc is generated.
Since the place where the periodic arc is generated has already been cleaned by the A period arc, even if the cleaning effect of the B period arc is weak, it does not adversely affect the welding result, and the welding at the intended place can be performed.

FIG. 1B shows an AC welding current waveform when the cleaning effect is weakened. The difference in the waveform of the A cycle in FIG. 1A and FIG. 1B is the difference in the strength of the cleaning effect. Adjustment of the strength of the cleaning effect is EP (electrode plus) during one cycle of the AC cycle.
This is done by changing the time ratio of.

50 to 100 of the commonly used AC frequency
Hz, and assuming that the welding speed is 1 m / min, the moving distance of the arc per AC cycle is 0.2 to 0.3 mm,
It is within a range that can be sufficiently covered by one cleaning effect. Further, even if the B cycle is 3 to 4 with respect to the A cycle 1, the moving distance is only 1 mm, which is within the range of the cleaning effect. Therefore, the repetition ratio of A cycle and B cycle is 1: 1.
Even if it is set to about 1: 4, welding is not adversely affected.

In order that the arc of B cycle, which has a weak cleaning effect, does not adversely affect the welding result, the next A cycle must come before the arc moves from the range cleaned by one A cycle. is there. The upper limit of the repetition rate of the A cycle and the B cycle is determined by the welding speed and the AC frequency, and is given by the following equation.

I = N · V / F where N: the upper limit of the repetition rate of A cycle and B cycle V: welding speed F: AC frequency I: range cleaned by one A cycle According to the AC arc welding machine of the embodiment, the time ratio of EN (electrode minus) in one cycle of AC is small, the cleaning effect is enhanced but the directivity of the arc is weak A cycle, and EN in one cycle of AC. The time ratio of (electrode minus) is large and the cleaning effect is weak, but the directivity of the arc is good. By repeating the B cycle alternately or at a specific ratio, the cleaning and the directivity of the arc can be made compatible, which is excellent. Welding results can be obtained.

In the above embodiment, a rectangular wave is used as the AC waveform, but it goes without saying that the present invention can be applied to a waveform using a waveform other than the rectangular wave. Further, in the above-mentioned embodiment, the ratio of the A cycle to the B cycle is explained as 1: 1, but other ratios can be applied. In the above embodiment, EP (electrode plus) in one AC cycle of B cycle is used.
Although the time ratio of is set to be constant without adjusting the strength of the cleaning effect, it goes without saying that it may be changed by adjusting the strength of the cleaning effect.

[0017]

As is clear from the above description, in the present invention, in AC arc welding, the cycle in which the time ratio of EN (electrode minus) occupying in one cycle of AC is small is A cycle, and one cycle of AC is By setting the cycle having a large time ratio of EN (electrode minus) shown therein as the B cycle, and by alternately outputting the A cycle and the B cycle at a ratio of 1: 1 or other, compared with the conventional method, Even if the cleaning effect is enhanced, excellent arc directivity can be obtained.

[Brief description of drawings]

FIG. 1 is a waveform diagram showing a relationship between a waveform and a cleaning effect in the AC arc welding method of the present invention.

FIG. 2 is a waveform diagram showing the relationship between the waveform and the cleaning effect in the conventional AC arc welding method.

[Explanation of symbols]

 A EN (negative electrode) time ratio is small current waveform B EN (negative electrode) time ratio is large current waveform

Claims (1)

[Claims] 1. In AC arc welding, a cycle having a small EN (electrode minus) time ratio in one AC cycle is defined as an A cycle, and a EN (electrode minus) time ratio shown in one AC cycle is large. An AC arc welding machine in which the cycle is a B cycle and the A cycle and the B cycle are alternately output at a ratio of 1: 1 or other ratio.