JPS59150673A - Pulse welding method - Google Patents

Abstract

PURPOSE:To stabilize the arc state without regulating pulse current and to improve the quality in a weld zone by superposing the pulse current of which the frequency is changed at every specified period on the base current and performing welding. CONSTITUTION:When pulse peak current IP is superposed on base current IB, the pulse frequency changes from a high to low frequency and this change is repeated at a period T. The pulse frequency may be changed from a low to a high frequency in this case. Although the change of the frequency (f) is linear, said frequency may be changed curvilinearly. If the welding is performed by changing repeatedly the pulse frequency at every period in the above-mentioned way, the transfer of the molten metal at the tip of the welding wire arises one time at every period T. There is therefore no need for adjusting the pulse frequency.

Description

[Detailed Description of the Invention] This is an improvement in the method of selecting the frequency of pulsed current.

The welding method that uses superimposed pulsed current provides stable welding conditions. It has been widely used in recent years for purposes such as improving the quality of welded parts. However, in welding with a superimposed i < Lus current (hereinafter referred to as pulse welding), the peak value of the Notels current, the pulse duration, and the selection of the pulse frequency have a significant influence on the stability of the welding arc and the quality of the weld.

(1) Figure 1 shows the waveform of a conventional pulsed welding current, with the welding current I on the vertical axis and time T on the horizontal axis.The welding arc has a preset base current I.
Superimposed on B, a peak current ■ waits for 1]1 of the pulse current IP to flow.

The pulse frequency in the second case is a preset constant frequency.

In pulse welding, when droplets migrate from the tip of the welding wire, the droplets migrate in an orderly manner depending on the combination of welding current, width of the pulse current, pulse current value, pulse frequency, wire diameter of the welding wire, etc. A good weld is made. However, in actual welding, these welding conditions are constantly changing, and because the pulse frequency is constant, they often deviate from the optimal conditions. As a result, the arc condition becomes unstable and welding defects occur.

The present invention was conceived in view of the above points.

This method provides a stable pulse welding method by simply changing the pulse frequency of pulse welding periodically, eliminating the need for complex pulse condition settings or welding condition control devices.

This embodiment will be explained below with reference to FIGS. 2 to 4. FIG. 2 shows the waveform of the welding current according to the present invention, with the welding current {circle around (2)} plotted on the vertical axis and time T plotted on the horizontal axis. When the pulse peak current IP is superimposed on the base current IB, the pulse frequency changes from high to low and is repeated at a period T.

At this time, the pulse frequency may change from low to high.

Figure 8 shows frequency f on the vertical axis and time T on the horizontal axis. In the case shown here, the change in frequency f is linear, but
It is also possible to change it in a curved manner as shown in FIG. By welding by repeatedly changing the pulse frequency every cycle, the pulse conditions necessary for stable transfer of the molten metal at the tip of the welding wire are always present, and droplet transfer occurs once every cycle T. arise.

Therefore, according to the pulse welding method of the present invention.

(3) There is no need to adjust the frequency of the pulse condition.

A stable arc condition is always obtained, and good welds can be obtained.

For example, pulse frequency f = 15-100001 (z
, the period TI = 0.01 to 1 sec, the repetition frequency is 100 to '/2 (Hz), and if the pulse frequency f is selected in the high range, the repetition period is short (if the pulse frequency f is selected in the low range) If so, the repetition period should be long. These should be selected in advance based on welding conditions, welding wire diameter, welding Ni!, pulse width, pulse peak current, base current, shielding gas, etc.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the pulse waveform of the prior art, FIG. 2 is an explanatory diagram of the pulse waveform of the method of the present invention, and FIGS. 3 and 4 are charts showing the relationship between pulse frequency and time of the method of the present invention. . ■...Welding current, T...hours ftJ], T+...pulse repetition J? 1lXIJ, f...Pulse frequency, w...Pulse middle Fig.
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Claims (1)

[Claims] In the arc welding method in which welding is performed by superimposing pulsed currents, +-, 1: A pulsed welding method characterized by superimposing pulsed currents in which the frequency of the distributed pulsed current is changed at regular intervals.