JPS6217162Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention alternately supplies a pulse current and a base current, compensates for fluctuations in the base current after the supply of the pulse current ends, and achieves good welding results. The present invention relates to a pulse arc welding machine that can be obtained.

[Conventional technology]

Generally, a pulse arc welding machine supplies a low-output DC base current (hereinafter referred to as base current) and a periodic pulse current larger than the base current to a welding load consisting of a consumable electrode and a base metal. The wire, which is a consumable electrode, is fed by a wire feeding device, and the molten metal of the fed wire is turned into small spray-like particles by the pinch force of the pulsed current. It has the feature of separating from the tip of the wire at high speed and suppressing spatter.

As shown in Fig. 1, the conventional pulse arc welding machine reduces the voltage of the three-phase AC from the three-phase AC power supply terminal 1 by the main transformer 2, and converts the output of the main transformer 2 into multiple rectifiers. A three-phase half-wave rectifier 3 consisting of a diode Da rectifies the base current Ib from the rectifier 3 through the first and second DC reactors 4 and 5 to the wire 6 which is a consumable electrode and the base material 7.
is supplied to the welding load 8 composed of. Note that the wire 6 is fed by a wire feeding device 9. Also,
The second DC reactor 5 has a large reactance component in order to prevent arc breakage due to the base current Ib, and improves ripple.

On the other hand, the two-phase AC from the three-phase AC power supply terminal 1 is transformed by the sub-transformer 10, and the output of the sub-transformer 10 is converted by two rectifying diodes Da and two controlled rectifying elements, thyristors Db. The rectified current is rectified by the pulse current control rectifier 11, and the rectified current from the pulse current control rectifier 11, that is, the periodic pulse current Ip that is larger than the base current Ib, is passed through the pulse current detector 12 and the second DC reactor 5. and supplies it to the welding load 8. Further, the detection signal of the pulse current detector 12 and the pulse reference signal of the pulse current reference power supply 13 that sets the value of the pulse current Ip are compared and amplified by the pulse current comparison amplifier 14. The output of is input to the pulse current gate drive circuit 15, and the control angle of each thyristor Db is controlled by the control signal of the pulse current gate drive circuit 15, and the pulse current Ip from the pulse current control rectifier 11 is controlled as a constant current. At the same time, the pinch effect caused by the pulse current Ip is controlled to be constant against fluctuations in the three-phase AC power supply, thereby stabilizing the arc. In addition,
A pulse control device 16 is constituted by a pulse current comparison amplifier 14 and a pulse current gate drive circuit 15.

[Problems that the invention attempts to solve]

By the way, in this case, as shown in FIG. 2, while the pulse current Ip is being supplied to the welding load 8,
Since the output voltage of the pulse current control rectifier 11 is controlled to be higher than the output voltage of the three-phase half-wave rectifier 3, the base current Ib is cut off. However, due to the reactance component of the first DC reactor 4, the pulse current
The rise of the base current Ib after Ip is supplied is delayed, and a so-called dip occurs in the waveform of the base current Ib. At this time, arc breakage is more likely to occur, especially due to fluctuations in the arc length of the welding load 8 and camera shake. If a disturbance occurs, there is a problem that there is a very high possibility that arc breakage will occur.

Therefore, the technical problem of this invention is to improve the delay in the rise of the base current, supply a stable base current, and prevent arc breakage.

[Means for solving problems]

This invention was made with the above points in mind, and is a main control rectifier that has a main control rectifier element and supplies a DC base current via a DC reactor to a welding load consisting of a consumable electrode and a base metal. a base current gate drive circuit that outputs an ignition control signal for the main control rectifier; a sub-control rectifier that has a sub-control rectifier and supplies a pulsed current to the welding load; and a sub-control rectifier that detects the pulsed current. A sub-detector, a sub-reference power source that sets the value of the pulse current, and a sub-detection signal from the sub-detector and a sub-reference signal from the sub-reference power source are compared to control the ignition of the sub-control rectifier. A pulse arc welding machine comprising: a main detector for detecting the DC base current; a main reference power source for setting the value of the DC base current; a base current comparison amplifier that compares a main detection signal from the device with a main reference signal from the main reference power supply and inputs an output signal to the base current gate drive circuit;
The pulse arc welding machine includes a compensation capacitor provided between the output of the base current comparison amplifier and the output of the main reference power source to compensate for fluctuations in the DC base current.

[Effect]

Therefore, according to this invention, when the base current is supplied to the welding load following the periodic pulse current, the delay in the rise of the base current due to the reactance component of the DC reactor is prevented by the compensating capacitor, A stable base current is supplied, preventing arc breakage after the pulse current ends, and compensating for disturbances such as arc length fluctuations and camera shake, ensuring good welding results. You will get it.

〔Example〕

Next, this invention will be explained in detail with reference to the drawings from FIG. 3 showing one embodiment thereof.

(Configuration) In Fig. 3, the same symbols as in Fig. 1 indicate the same things, and the difference from Fig. 1 is that three rectifying diodes are used instead of the three-phase half-wave rectifier 3 in Fig. 1.
Da and three main control rectifying elements, thyristors
Db', and a main detector 18 for detecting the rectified current of the main control rectifier 17, that is, the base current Ib, between the main control rectifier 17 and the first DC reactor 4, Furthermore, the main reference power supply 1 that sets the value of base current Ib
9, the main detection signal of the main detector 18 and the main reference power supply 1
9, a compensating capacitor 21 connected between the input end and the output end of the base current comparison amplifier 20, and the output of the base current comparison amplifier 20. is input and outputs a main control signal for ignition control to each thyristor Db' of the main control rectifier 17. The gate drive circuit 22 constitutes the main control device 23, and the pulse current control rectifier 11, pulse current detector 12, pulse current reference power source 13, and pulse control device 16 shown in FIG. , a sub-detector, a sub-reference power source, and a sub-control device, and a pulse current detector, that is, the sub-detector 12.
The detection signal of is called a sub-detection signal, and the pulse reference signal of the pulse current reference power source 13 is called a sub-reference signal. In addition, each thyristor provided in the pulse current control rectifier, that is, the sub-control rectifier 11
Db is called a sub-control rectifying element.

(Operation) Then, as shown in Fig. 4a, the base current Ib is supplied to the welding load 8 for Tb time, and then
As shown in , pulse current Ip is applied to welding load 8 to Tp.
In this case, the output voltage of the sub-control rectifier 11 is controlled to be higher than the output voltage of the main control rectifier 17 during each Tp time when the pulse current Ip is supplied. Control rectifier 1
1, the value of the base current Ib becomes zero, and the main detection signal from the main detector 18 to the base current comparison amplifier 20 becomes zero.

By the way, at the time Tp when the pulse current Ip is supplied, the compensation capacitor 21 is not initially charged to the maximum value, and the capacitor 21 is not charged to the maximum value at the time Tp.
1, the output of the base current comparison amplifier 20 gradually increases as the capacitor 21 is charged, as shown in FIG. 2c.
As the output of the comparison amplifier 20 increases, the control angle of each thyristor Db' of the main control rectifier 17 becomes smaller due to the control signal from the base current gate drive circuit 22, and the base current Ib from the main control rectifier 17 increases. .

At this time, the output level of the base current comparison amplifier 20 becomes higher than the initial level at the end of the time Tp when the pulse current Ip is supplied, so the output level of the main control rectifier 17 becomes higher than when the base current Ib is supplied. It's summery.

Then, since the base current starts to flow when the pulse current Ip further decreases from a state in which the potentials at both ends of the first DC reactor 4 are equal due to a decrease in the pulse current Ip, the large base current Ib becomes earlier than before. It will flow from

Therefore, the potential E at the output terminal of the base current comparison amplifier 20 becomes E1 when the base current Ib starts to flow following the pulse current Ip, and becomes smaller than E1 when each base current Ib flows steadily. E2, the relationship E1>E2 is established, and the delay in the rise of the base current Ib due to the inductance components of the first and second DC reactors 4 and 5 is prevented, the base current Ib is stabilized, and the welding load is reduced. 8, as shown in FIG. 2d, the base current Ib and the pulse current Ip are repeatedly supplied, the drop in each base current Ib following the pulse current Ip is improved, and arc breakage is prevented. Furthermore, even with respect to disturbances such as fluctuations in the three-phase AC power supply, fluctuations in base current Ib due to disturbances are compensated for.

In the above embodiments, the main control rectifier 17 was configured by a so-called three-phase half-wave rectifier circuit, but it is of course possible to configure it by other rectifier circuits, such as a double star-shaped six-phase rectifier circuit with an interphase reactor. be.

[Effect of idea]

As described above, according to the pulse arc welding machine of this invention, when the base current is supplied to the welding load following the periodic pulse current, the delay in the rise of the base current due to the DC reactor is prevented by the compensation capacitor. This makes it possible to supply a stable base current, prevent arc breakage especially after the end of the pulse current, and also compensate for disturbances, making it possible to obtain good welding results. Can be done.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram of a conventional pulse arc welding machine.
Figure 2 is the output waveform diagram of Figure 1, Figures 3 and 4.
The figure shows one embodiment of the pulse arc welding machine of this invention, Figure 3 is a wiring diagram, Figure 4 a is a waveform diagram of the base current, Figure b is a waveform diagram of the pulse current, Figure c is the base current diagram. Figure d is a waveform diagram of the current supplied to the welding load. 4, 5...first and second DC reactors, 6...
Wire, 7... Base material, 11... Sub-control rectifier, 1
2... Sub-detector, 13... Sub-reference power supply, 16...
Sub-control device, 17... Main control rectifier, 18... Main detector, 19... Main reference power supply, 23... Main control device.

Claims (1)

[Scope of utility model registration request] A main control rectifier that has a main control rectifier and supplies a DC base current via a DC reactor to a welding load consisting of a consumable electrode and a base metal, and a base current that outputs an ignition control signal for the main control rectifier. a sub-control rectifier having a sub-control rectifying element and supplying a pulsed current to the welding load, a sub-detector for detecting the pulsed current, and a sub-reference power source for setting the value of the pulsed current. , a sub-control device that compares a sub-detection signal from the sub-detector with a sub-reference signal from the sub-reference power source and outputs a sub-control signal for controlling the ignition of the sub-control rectifying element. In the welding machine, a main detector that detects the DC base current, a main reference power source that sets the value of the DC base current, a main detection signal from the main detector, and a main reference signal from the main reference power source. a base current comparison amplifier that compares and inputs an output signal to the base current gate drive circuit; A pulse arc welding machine equipped with a compensation capacitor for compensation.