JPS6365432B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in pulsed arc welding equipment, and in particular, to suppress the loud arc noise that occurs during welding and which causes discomfort to humans due to ripples in the pulsed current waveform. This is a pulse current waveform with smaller ripples.

Conventionally, this type of welding has been carried out as shown in Fig. 1. In the figure, 1 is a DC power supply circuit which receives an AC power supply as an input, and is composed of diodes 2 to 7 and a smoothing capacitor 8. 9 is a group of switches in which a plurality of transistors 10 ₁ to 10 _o are connected in parallel, and the direct current from 1 is input, and by turning on and off at 10 ₁ to 10 _o , a pulsed current is generated. There is.

11 is a flywheel diode, 12 is a DC reactor, 14 is a wire electrode winding frame, 15 is a wire feeding motor, 16 is a cable, 17 is a torch, 18 is a base material, and 19 is generated between the wire electrode and the base material. Welding arc, 20 is a shunt for detecting the peak current, 21 is the peak current detected by shunt 20, the voltage of the welding arc generated between the wire electrode and the base metal (hereinafter referred to as welding arc voltage), and the wire feeding speed. A control circuit for controlling ON-OFF the transistors 10 ₁ to 10 _o in the switch group 9 using the input as input, and 13 is a small DC current _B.
It is an auxiliary power supply that supplies

Next, to explain the operation, in the above configuration, in order to obtain a proper welding state, the wire feed amount and welding current determined by the plate thickness of the base material 18, etc. are determined by the feed speed of the wire feed motor 15 and the switch group. It is adjusted by the number of pulse currents supplied per unit time at 9 . Also, 1 is determined by the wire material and its diameter, etc.
The peak current and pulse width of the pulse current are shunt 2.
0, the control circuit 21 compares the detected peak current and welding arc voltage with predetermined values, and turns the output currents i ₁ to i _o on and off according to the values.
Turn on transistors 10 ₁ to 10 _o of switch group 9
- Turned off and adjusted to the specified value.

Next, the pulse current waveform obtained by this welding machine will be explained with reference to FIG. In the figure,
22 are currents i ₁ to _{i o} flowing to the bases of the transistors, 23 ₁ , 23 ₂ and 23 _o are currents ₁ to _o flowing to the emitters of the respective transistors,
24 is a pulse current waveform. Also, the broken line 24
1 shows the pulse current when the transistors 10 ₁ to 10 _o are turned on for a long time. First, at time t=0, if the base input currents i ₁ to i _o are caused to flow and the transistors 10 ₁ to 10 _o are turned on, then
A pulse current that is a composite of currents ₁ to _o flowing through each emitter flows, and the current is shunt 2.
The transistors 10 ₁ to 10 _o are turned off when the value reaches _PA (point t ₁ ). When the transistors ₁₀₁ to _10o are turned off, the energy accumulated in the DC reactor 12 is transferred from the welding torch 17 to the base material 19 and the flywheel diode 1.
1, and the pulse current is t ₁ - in FIG.
When the pulse current detected by the shunt 20 attenuates as during _t2 and reaches _PB , the transistors ₁₀₁ to _10o are turned on and the pulse current reaches _PA.
(t ₃ points), transistors 10 ₁ to 10 _o
Turn off.

As described above, the transistors 10 ₁ to 10 _o are repeatedly turned on and off until t ₇ to complete one pulse current waveform as shown in FIG. 24.

Since the conventional pulsed arc welding device is configured as described above, it has a single pulsed current waveform as shown in Fig. 224, which increases the ripple of the pulsed current waveform and reduces the arc noise generated during welding. It had the disadvantage of being expensive. In addition, with this device, if the difference between _PA and _PB in Figure 2 is reduced in order to reduce the ripple, and the transistor is turned on and off repeatedly, the switching loss of the transistor will increase and the transistor will be heated abnormally. There are disadvantages such as damage.

This invention was made in order to eliminate the drawbacks of the conventional switch as described above, and includes a second switch group (hereinafter referred to as switch group B) in addition to the conventional switch group 9 (hereinafter referred to as switch group A). , when switch group A is ON within the pulse period T, switch group B is turned OFF, and when switch group A is OFF, switch group B is turned ON, without increasing the switching loss of the transistor.
It is an object of the present invention to provide a pulsed arc welding device that can reduce ripples in a pulsed current waveform.

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 3, the four terminals a, b,
c, d are the four terminals a,
These correspond to b, c, and d, respectively. Note that in FIG. 3, the circuit configuration other than the circuits within the four terminals a, b, c, and d is the same as the conventional circuit configuration, and is therefore not shown. In the figure, 9 is switch group A, 91 is switch group B, 10 ₁ to 10 _o , and 1
01 ₁ to 101 _o are transistors, 11,
111 is a flywheel diode for the first and second switch groups A and B, 12 and 121 are DC reactors, and 211 is a flywheel diode for the first and second switch groups A and B.
This is a control circuit that performs ON-OFF control. within 211
Z ₁ ~ _{Z o} and Y ₁ ~ _{Y o} are each one pulse period T
When Z ₁ to Z _o are ON (i.e., when base currents i ₁₁ to i _1o flow), Y ₁ to Y _o are OFF, (i.e., i ₂₁ to
i _2o becomes zero) when Z ₁ ~ Z _o is OFF (i.e. i ₁₁ ~
When i _1o is zero) Y ₁ to Y _o are ON (that is, i ₂₁ to _{i 2o} are flowing).

Next, the operation of the present invention will be explained according to the pulse current waveform shown in FIG. 22A and 22B are the base currents i ₁₁ to i _1o and i ₂₁ to i _2o of the transistors in the respective switch groups A and B, 23
A ₁ , 23A ₂ ~ 23A _o and 23B ₁ , 23B ₂ ~ 23
B _o is the emitter current of each transistor ₁₁ to _1o and ₂₁ to _2o , 24A and 24B are switch group A
and the current flowing from B and the DC reactor 12,
_A and _B are a combination of currents flowing through the flywheel diodes 11 and 111 due to the energy stored in 121, and 25 is a pulse current that is a combination of _A and _B.

Switch group A is turned on at time t=0, and when the pulse current detected by shunt 20 reaches _PA ,
Switch group A is turned OFF, and at the same time switch group B is turned ON. Then, _B rises, _A decays as the energy stored in the DC reactor 12 is released, and when the pulse current reaches _PB , switch group A turns on, and at the same time switch group B turns on.
When turned OFF, _B attenuates as the energy stored in the DC reactor 121 is released, and _A becomes
It rises to _PA , and when it reaches _PA , switch group A
is turned OFF, and switch group B is turned ON. Similarly, switch group A is repeatedly turned on and off, and at time t
= At t ₇ , switch group A is turned off, and switch group B is turned off.
Turn it on. Then, A attenuates as the energy stored in the DC reactor 12 is released, and becomes zero at time t= _t10 . Also, switch group B is turned OFF at time t= _t8 . Then
_B attenuates as the energy stored in the DC reactor 121 is released, and _B becomes zero at time t= _t9 .

In this way, switch group A is set within pulse period T.
When ON-OFF is repeated and switch group B is turned OFF at time t= _t8 , A becomes a current like (24A) and _B becomes a current like (24B). Therefore, the pulse current becomes a combination of A and _B , and has a characteristic as shown in 25 in FIG. As a result, the pulse current ripple ( _PAO - _PB
O ) becomes smaller.

In addition to the first switch group consisting of transistors that generate pulsed current, this invention newly provides a second switch group consisting of transistors that generate pulse current.
A control circuit is provided so that when the first switch group is on, the second switch group is turned off, and when the first switch group is off, the second switch group is turned on. Since the pulsed current is generated under control, the ripple of the pulsed current can be reduced and the arc noise during welding can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a power supply circuit configuration of a conventional pulse arc welding device, FIG. 2 is a diagram showing a pulse current waveform of a conventional pulse arc welding device, and FIG. 3 is a diagram showing a power supply circuit configuration of an embodiment of the present invention. FIG. 4 is a diagram showing the pulse current waveform of this embodiment. In the figure, 1 is a DC power supply, 9 is a first switch group A, 91 is a second switch group B, 11, 11
1 is a flywheel diode, 12 and 121 are DC reactors, 13 is an auxiliary power source, 14 is a wire electrode winding frame, 15 is a wire feed motor, 17 is a welding torch, 18 is a base material, 20 is a shunt for current detection, 21 and 211 are control circuits. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1 In a pulsed arc welding device that applies a welding current obtained by superimposing a pulsed current to a direct current supplied from an auxiliary power source 13 between a welding torch 17 and a base metal 18 for welding, a DC power supply circuit 1 and a plurality of transistors are connected in parallel. A first switch group 9 connected to the output terminal of the DC power supply circuit 1 generates the pulse current by turning on and off these transistors, and the magnitude of the pulse current flowing through the first switch group 9. a current detection shunt 20 for detecting the current detection shunt 20, a first DC reactor 12 connected between the output terminal of the first switch group 9 and the input terminal of the current detection shunt 20, and the output of the DC power supply circuit 1. Terminal and the above current detection shunt 20
a second switch group 91 connected between the output terminal of the second switch group 91 and the welding torch 17; a second DC reactor 121 connected between the output terminal of the second switch group 91 and the welding torch 17; shant 20
When the detected pulse current reaches the first current value, the transistors of the first switch group 9 are turned off, the transistors of the second switch group 91 are turned on, and the detected pulse current reaches the first current value. The present invention is characterized by comprising a control circuit 211 that turns on the transistors of the first switch group 9 and turns off the transistors of the second switch group 91 when a second current value smaller than the current value is reached. Pulsed arc welding equipment.