JPS58103965A - Multiple-electrode pulsed arc welding machine - Google Patents

Abstract

PURPOSE:To reduce loss of energy and make the size of the machine small by providing switching elements between an electric power source and plural electrodes and enabling to supply energy accumulated in wiring inductance to electrodes. CONSTITUTION:The machine consists of plural electrodes 3, 3' connected in parallel, switching elements of transistors Q3, Q4 switched in series by high frequency, fly wheel diodes D1, D2 and a switching device that switches energizing of switching elements successively by low frequency. Above-mensioned diodes D1, D2 are installed in parallel to welding load and supply accumulated energy accumulated in the wiring inductance during on-period of transistors Q3, Q4 to electrodes 3, 3' during off-period. By this welding machine, loss of energy is decreased and the machine can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-electrode pulse arc welding machine that reduces energy loss and is miniaturized.

Generally, in order to improve welding efficiency, a multi-electrode pulse arc welding machine using two or more electrodes is used. For example, a two-electrode pulse arc welding machine is shown in Fig. 1. It is configured as follows. In the same figure,
(1) is a DC power supply device that rectifies AC from an AC N source (not shown) and supplies smoothed DC to the welding load; (2) is a workpiece connected to the positive terminal of power supply device (1); The base metal is +33, (3'r is the first and second electrodes that constitute the welding load together with the base metal (2), (41, (45 are one end or the first and second electrodes (3), respectively.

(1st and 2nd coupling coils connected to 31), which apply high frequency high voltage from a high frequency high voltage power source (not shown) at the time of arc start between each electrode +a), +3) and the base material (2). applied to improve arc start characteristics.

(Ql') and (Q2) respectively have the collectors as the first . The first NPN type switching element is connected to the other end of the second coupling coil +4+ and <4f. The first and second transistors (5) have one end connected to both transistors (Ql)
, (Q2) is a current detector connected to the emitter to detect the welding current and output a detection signal, (6) is an NPN transistor whose collector and emitter are respectively the other end of the current detector (5) and the power supply device. The series regulator (7) is connected to the negative terminal of the series regulator (6) and the negative terminal of the first. Second transistor (Ql).

(Q2) is a control device that controls the switching operation of the series regulator (6), and flows current to the base of the transistor of the series regulator (6) according to the detection signal output from the current detector (5). In addition to controlling the collector current of the welding current and performing constant current control of the welding current, the first and second transistors (Ql)
, (Q2), a current is applied at regular intervals alternately to the base of the first. Second transistor (Ql).

Controls the switching operation of (Q2). (10 is a DC power supply for supplying base current, the positive terminal is connected to the base material (2), and the two negative terminals are connected to the first and second coupling coils (4+, t4s, respectively). .The second polarity 13) is connected to +3g, and the first and second transistors (Ql).

During the off period of the switching operation (Q2), a base current is passed through the base material (2) and each electrode +3+, (3'r) to prevent arc breakage.

Then, the control device (7) turns on the transistor of the series regulator (6), and as shown in FIG. From the base material (2), the first electrode 13), the first coupling coil (4)
.

A current flows through a series circuit consisting of a first transistor (Ql), a current detector (5), and a series regulator (6). Next, as shown in Figure (a), while the first transistor (Ql) is turned off by the control device (7), as shown in Figure (b), the second transistor (Q2) is turned off. When turned on, the power supply (1) and the base material (
2), the second electrode (31, the second coupling coil (41), the second transistor (Q2), the current detector (5+), and the series regulator (6). At this time, the first transistor ( The switching frequencies of Ql) and the second transistor (Q2) are set by the control device (7) to a range of several Hz to I KHz.

Furthermore, the off period of the first transistor (Ql) and the second transistor (Q2), the base material I 21 and the first electrode (
3), each welding load consisting of the base metal (2) and the second electrode (31) is connected to the base current supply DC power supply Ql in order to prevent arc breakage due to no current being supplied from the power supply (1). A low ripple base current is supplied to both welding loads as shown in FIG. 2(C).

Welding currents as shown in +(l) are supplied, and pulse arc welding is performed alternately by both electrodes +3) and +3i.

However, in this case, the series regulation (6
) and the first and second transistors (Ql), (
Q2) is provided as a separate circuit, which complicates the circuit configuration and requires a large capacity series regulator (6).
side will be required.

That is, for example, when the power supply (1) outputs a voltage of 4
When 20 KW of DC power with 0 V and output current of 500 A is supplied to the welding load, due to the load fluctuation of the welding load, the base material (2), which is the welding load, and each electrode (3),
ta (assuming that the welding voltage between
Sunawachi 10Kw (20 x 50OA) The surplus 10KW of power that is not consumed is connected to the series regulator (6
), and assuming that the voltage fluctuation of the power supply (1) is ±10%, a large capacity transistor of approximately 12 Kw is required as a transistor for the series regulator (6). However, since it is not possible to obtain such large capacity transistors, a series regulator (6) that operates multiple transistors in parallel is used.
However, it generally requires a long time to manufacture, is large in size, and has the drawbacks of increasing heat loss due to the series regulator (6).

This invention was made with the above points in mind,
Next, this invention will be explained in detail with reference to the drawings from FIG. 3 onwards showing an embodiment thereof.

In those drawings, the same symbols as in FIG. 1 indicate the same things, and the difference from FIG. An NPN type $, which is a switching element, is connected to the other end of the 1st @22 coil (4) and t4f connected to the second electrode +a+ and r3s through the 1st and second current detectors av and as, respectively. 3. Fourth transistor (Qa)
, (Q4) are connected, and the emitters of both transistors CQ8), (Q4) are connected to the negative terminal of the power supply (1), and each output setting device f8), (
9) Setting signal output from each current detector 0υ,
Both transistors (
A control signal, which is a current signal, is output to the bases of Qa ) and (Q4), and both transistors (Qa ) and (Q
4) are alternately switched and energized at a low frequency of several H2 to 1 KHz, and both transistors (Qa) and (Q
4) respectively at a high frequency of 1.5 KHz or higher, both transistors (Qa) and (Q4)
A control device 03 is provided, which is a switching means for constant current control of the collector current of first and second flywheel diodes (DI) in parallel to a series circuit consisting of a welding load consisting of a material (2) and a second electrode (31) and a second coupling coil (41), respectively;
(D2) is connected and provided, and both flywheel diodes (
DI), (D2), both transistors (Qa).

(Q4) during the on period. Second coupling coil (4+,
(4f) and the energy stored in the wiring inductance is supplied to each electrode (3+, +3f) during the off period.

Then, as shown in FIG. 4(a), when a control signal, which is a high frequency → pulse current signal, is output from the control device 0 to the base of the third transistor (Qa), as shown in FIG. 4(b). As shown in @3), since the transistor (Qa) is turned on according to the control signal, during the on period of the third transistor (Qa), the power supply from the power supply (1) to the base material (2), the first electrode 1
3), first coupling coil (4), first current, detector 01)
A current 11 flows through the series circuit consisting of the third transistor (Qa) and the third transistor (Qa), and the on-period of the third transistor (Qa) is during the off period of the third transistor (Qa), as shown in FIG. A current based on the stored energy of L''/dt stored in the first coupling coil (4) and the wiring inductance flows through the first flywheel diode (DI), the base material (2), and the first electrode (3). and the first
The current flows through a series circuit consisting of a coupled coil (4). Therefore, the welding load consisting of the base material (2) and the first electrode (3) is connected via the third transistor (Qa) and the first flywheel diode (DI) to the welding load as shown in FIG. A current Ia (It + T2) flows.

At the same time, the control device 01 controls the third transistor (Qa
) is stopped, and at the same time, as shown in FIG. 4(e), a control signal, which is a high-frequency pulse current signal, is output to the base of the fourth transistor (Q4). Q4) is turned on according to the control signal, so during the ON period of the fourth transistor (Q4), the power supply (1) supplies the base material (2), the second electrode (31, the second coupling coil (41, A series circuit consisting of the second current detector 02 and the fourth transistor (Q4) is connected to a current I
t' flows, and during the off-period of the fourth transistor (Q4), the accumulation of L d I /a t accumulated in the second coupling coil (4 (and the wiring inductance) occurs during the on-period of the fourth transistor (Q4). A current I2' similar to the above-mentioned current 2 based on energy flows through the second flywheel diode (D2) and the base material (2).

It flows into a series circuit consisting of the second electrode (31) and the second coupling coil (41. Therefore, the base material (2) and the second electrode (31 and the second flywheel diode (+) 2)
A composite current Is' similar to the composite current ①8 above is generated via
(I +' + I2') flows.

Furthermore, the off period of the third transistor (Qa) and the fourth transistor (Q4), the base material (2) and the first electrode (
3), each welding load consisting of the base material f21 and the second electrode (G) is not supplied with current from the power supply (1).
In order to prevent arc breakage caused by
, I4' are respectively supplied, and both the welding loads are supplied with:
Welding currents Io (Ia + I4) and IO'(I8' + I4') as shown in Figure 4) and (g), respectively.
) is supplied, and pulse arc welding is performed alternately by both electrodes +3) and +3f.

Therefore, as mentioned above, the power supply device (1)
For example, the output voltage is 40V and the output current is 500A.
When KW DC power is being supplied to the welding load,
Due to load fluctuations in the welding load, the base material, which is the welding load,
Even if the welding voltage between each electrode +31, +3f is reduced to 20V, each transistor (Qa), (Q
4) is switched at high frequency by the control device 01, the collector-emitter voltage when the transistors (Qa) and (Q4) are turned on is several ■, and even considering the voltage fluctuation of the power supply device (1), , both transistors (Q
a).

The energy loss in (Q4) is low at about IKW, and the energy loss in the first
The energy loss is approximately 1/1 of the energy loss caused by the series regulator (6) shown in the figure, and there is no need to provide the conventional series regulator (6), resulting in less energy loss.
A small multi-electrode pulse arc welding machine can be provided.

Furthermore, depending on the detection signals from each current detector αD and αGong,
Each transistor (Qa), (Q4
) by making the frequency of the control signal output to the base even higher than in the cases of FIGS. 4(a) and (e), it is possible to supply a welding current with small ripples.

As described above, according to the multi-electrode pulse arc welding machine of the present invention, the multi-electrode pulse arc welding machine performs welding by sequentially supplying current from a DC power source to a plurality of electrodes connected in parallel. A switching element that is switched at a high frequency is provided in series between each electrode and the power source, and the energy accumulated in the wiring inductance during the on period of the switching operation of each switching element is connected in parallel to the welding load and is transferred to the off period. By providing each electrode switching means, energy loss can be reduced and downsizing can be achieved.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram of a conventional multi-electrode pulse arc welding machine.
Figure 2 is a timing chart for explaining the operation of each part in Figure 1, where (a) and (b) are the collector currents of the first and second transistors, and (c) and (d) are the collector currents supplied to each electrode. Welding current, Figure 3 The following drawings show one embodiment of the multi-electrode pulse arc welding machine of the present invention, Figure 3 is a wiring diagram, and Figure 4 is a timing chart for explaining the operation of each part in Figure 3. (a) is the control signal output from the control device to the base of the third transistor, (h) is the collector current I+ of the third transistor, (c) is the current flowing through the first flywheel diode ■2, (( 1) is the combined current T8 flowing through the first electrode, (e) is the control signal output from the control device to the base of the fourth transistor, and (ge) is the welding current IO1 flowing through the first electrode. Welding current IO
′. (1)...2 DC power supply device, (2)...base material, t3
), taS...first degree second electrode, (Qa), (
Q4')...3rd. Fourth transistor, (1)I)
, (D2)...first. second flywheel diode,
03...Control device. Agent: Patent Attorney Ryutabe Fujita, Ward 1, Figure 2

Claims (1)

[Claims] ■ In a multi-electrode pulse arc welding machine that welds by sequentially supplying one current from a DC power source to multiple electrodes connected in parallel, high-frequency switching is performed in series between each electrode and the power source. A switching element is provided, and a flywheel diode is connected in parallel to the welding load, and a flywheel diode is connected in parallel to the welding load to supply the stored energy stored in the wiring inductance during the ON period of the switching operation of each of the switching elements to each of the electrodes during the OFF period. 1. A multi-electrode pulse arc welding machine, characterized in that the multi-electrode pulse arc welding machine is provided with a switching means for sequentially switching energization of each of the switching elements at a low frequency.