JPH048143B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pulse arc welding method, and particularly to a welding method suitable for eliminating arc breakage that occurs during welding.

[Prior art]

Conventionally, in this type of pulsed arc welding method, as shown in FIG. The aim was to obtain a stable arc with almost no spatter over a wide range of currents from small to large. However, there are drawbacks such as arc breaks occurring frequently during welding at the edges or horizontal fillets of the workpiece, or undercuts occurring in the vertical plates of horizontal fillets, making it difficult to obtain a good weld. It was hot. Conventionally, methods have been considered to prevent this type of arc breakage, such as setting the base current high or increasing the base current when the arc voltage exceeds a set value during the base current period. None of these methods were able to completely prevent arc breakage.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned matters, and its purpose is to provide a pulsed arc welding method that completely prevents arc breakage that occurs during welding and allows a stable arc to be obtained at all times. It is in.

[Summary of the invention]

The present invention has been made based on the findings that the cause of arc breakage is directly due to the magnetic blowing phenomenon, and indirectly due to the burning phenomenon of the wire to the power supply chip while pulse current is being applied. It is something. In conventional pulsed arc welding, the base current is set to a low constant current value that can maintain the arc, so there is little arc stiffness, and therefore it is greatly influenced by the magnetic field formed around the arc. For example, when horizontal fillet welding of mild steel is performed, even if it is considered to be stable by visual observation or observation of welding current and voltage waveforms, when the phenomenon is observed with a high-speed camera, pulses as shown in Figure 2a are observed. During the current period, the bell-shaped arc is stable in the axial direction of the wire, but during the base current period, it is all biased toward the vertical plate and moves unstablely. At this time, as the arc length increases, the bias becomes even more pronounced, and in the worst case, the second
Arc breakage occurs as shown in Figure b. Furthermore, when a pulse current flows, a wire seizure phenomenon occurs within the power supply chip, causing the wire to temporarily stop, lengthening the arc length and causing arc breakage.

From the above, in order to prevent arc breakage, it is necessary to quickly eliminate wire seizure after the end of the pulse current and to always keep the arc stable in the axial direction of the wire.

In the present invention, the molten metal formed at the tip of the wire is reliably separated by the first pulse current, that is, one droplet is transferred in one pulse, and the second pulse current is applied to the first pulse current. This eliminates the seizure of the wire that occurs as a result, and also stabilizes the arc in the axial direction of the wire to completely prevent arc breakage.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

In FIG. 3, 4 is a DC power supply, 5 is a smoothing capacitor, 6 is a current limiting element that controls the output current, and 7
8 is a current delay element, 8 is an electrode wire, 9 is a feeding roller that feeds the electrode wire, 10 is a feeding motor that rotates the feeding roller 9, 11 is a power feeding chip, 12
is an arc, 13 is a base material, 14 is a ring current element, 1
5 is a current detector, 16 is a current value control circuit, 17 is an ignition circuit for current limiting element 6, 18 is a timer circuit, 1
9 is a current regulator, 20 is a voltage fine adjuster, 21 is a wire feed command circuit, and 22 is a feed motor drive circuit.

Next, the operation of the above embodiment will be explained. When a DC voltage is output from the DC power supply 4, it is sufficiently smoothed by the smoothing capacitor 5, and the current is passed through the current limiting element 6, the current delay element 7, and the power supply chip 11 to the electrode wire 8. An arc 12 is generated between the electrode wire 8 and the base material 13. Further, the first pulse frequency is set in the timer circuit 18 according to the command value of the current regulator 19. The current value control circuit 16 transmits a base current waveform including a preset first pulse waveform and a second pulse waveform to the first pulse frequency outputted by the timer circuit 18 and the current detector 1.
A signal based on the signal detected in step 5 is sent to the ignition circuit 1.
Output to 7. The ignition circuit 17 drives the current limiting element 6 using this signal. In addition, the wire feed command circuit 21 uses the command value of the current regulator 19 and the voltage fine regulator 2.
0 and the arc voltage value, a signal is output to the feed motor drive circuit 22.

FIG. 4 shows an example of a current waveform according to this embodiment. In the figure, base current I _B 1, first pulse current I _P
2. The first pulse current width T _P 3 is the same as in Fig. 1,
The molten metal generated at the tip of the wire is reliably separated by an electromagnetic pinch force determined by the pulse current 2 and the pulse current width _TP . Next, after T _BD 23 has elapsed since the first pulse current 2 began to decrease, a second pulse current I _BP 24 is caused to flow for a period of T _BP 25, thereby causing the first pulse current to burn into the power supply chip. This eliminates the need for wires. At this time, if T _BD 23 is shorter than 1 ms, the second pulse current will be superimposed on the first pulse current, and as a result, droplet detachment and transfer will be disturbed. Moreover, if it is longer than 5 ms, the arc length becomes long during this time and arc breakage is likely to occur. Therefore I _BD is 1m
It must be set to s≦T _BD ≦5ms. Furthermore, in order to quickly eliminate the wire sticking to the power supply chip and to keep the arc stable in the axial direction of the wire, the second pulse current I _BP must be set to 100 A or more. However, since the molten metal formed at the tip of the wire at this time has already been reliably separated by the first pulse current I _P 2, it will not separate by the second pulse current I _BP . If it is smaller than 100A, not only will it be impossible to eliminate the burn-in unless the pulse width T _BP is made longer, but the arc will not have enough rigidity to stabilize in the axial direction of the wire. Observing the arc phenomenon, in the range of I _BP = 60 to 90 A, in the case of horizontal fillet welding, the arc is biased to one point on the vertical plate, and an undercut occurs on the vertical plate.
Also, the pause time T _BB 26 of the second pulse current is 5 m.
If it is longer than s, arc breakage is likely to occur as in _TBD .

On the other hand, the second pulse current eliminates the wire sticking to the power supply chip and stabilizes the arc in the axial direction of the wire, allowing the wire to be fed smoothly. It becomes stable and becomes gradually shorter. Therefore, even if the next second pulse current is smaller than the first pulse current, the arc is stabilized in the axial direction. Therefore, arc breakage can be prevented without significantly increasing the average value of the base current.

From the above, by making the second pulse current waveform during the base current period an attenuated waveform, arc breakage can be prevented without disturbing droplet detachment and migration, and without increasing the average current too much. can do.

〔Effect of the invention〕

As described above, according to the method of the present invention, the molten metal generated at the tip of the wire is reliably separated by the first pulse current, and the molten metal generated at the tip of the wire is reliably removed during the first pulse period by the second pulse current during the base current period. This prevents the wire from sticking to the power supply chip, which occurs inside the wire, and the arc can always be stabilized in the axial direction of the wire, resulting in almost no spatter in a wide melting current range from low to high currents. Welding can be performed without arc breakage. Therefore, there is no need for post-treatment after welding, and high-speed welding is possible, so work efficiency is significantly improved.

[Brief explanation of drawings]

Fig. 1 is a current waveform diagram of the conventional pulsed arc welding method, Fig. 2 is an explanatory diagram showing the phenomenon of arc breakage,
FIG. 3 is a circuit diagram of one embodiment of the present invention, and FIG. 4 is a current waveform diagram according to one embodiment of the present invention. 2...First pulse current I _P , 3... First pulse current width T _P , 23... Second pulse current delay time T _BD , 24... Second pulse current I _BP , 25...
Second pulse current time T _BP , 26...Second pulse current pause time T _BB .

Claims (1)

[Claims] 1. In a pulsed arc welding method using a consumable electrode, a droplet formed at the tip of an electrode wire by a first pulse current having a large peak current I _BP applied between the base material and the electrode wire. The burning of the electrode wire is eliminated by separating the base current from the first pulse current and flowing a base current having a second pulse current having an attenuated waveform that is smaller than the first pulse current and whose peak current gradually attenuates. A pulsed arc welding method characterized by: 2 The time T _BD from when the first pulse current starts to fall until the second pulse occurs is 1.0~
The pulse arc welding method according to claim 1, wherein the pulse arc welding time is 5.0 ms. 3. The pulsed arc welding method according to claim 1, wherein the peak current _IBP of the second pulsed current is 100A or more.