JPS59218273A - Consumable electrode type pulse arc welding machine - Google Patents

Abstract

PURPOSE:To decrease the disturbance of an arc owing to magnetic blow in a low current region as well by suppressing the elongation of the arc to improve the linearity of the arc in the stage of base current. CONSTITUTION:A pulse frequency is increased with respect to a standard pulse current waveform in a consumable electrode type pulse arc welding machine. At least >=1 among the 1st changeover means S3, S4, S5 which change the respective set values to make the pulse width shorter or to decrease the peak current value, the 2nd changeover means S1 which changes the set base current value to increase the base current value with respect to the standard pulse current waveform and the 3rd changeover means S2 which changes the hysteresis width of on-off control so as to increase the amplitude of the base current with respect to the standard pulse current waveform are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a consumable electrode type pulse arc welding machine, and particularly to countermeasures against the magnetic blow phenomenon.

[Background of the Invention] FIG. 1 shows the relationship between the current waveform and arc shape used in a consumable electrode type pulse arc welding machine.

In (4) of the same figure, tp is the peak time and tntd base time, and the peak current control transistor is on/off controlled at the peak time tp except during the transition period, and at the base time tB, the base current IB is ♂±β(I+:
On/off control of the pace current control transistor is performed so that the pace current control transistor becomes the pace current setting value (±β: hysteresis width).

As a result, the welding machine output current transfers the droplet from the set pulse frequency pole wire to the base metal.

In conventional consumable electrode type pulse arc welding machines, the same
A standard pulse current waveform that maximizes the amount of wire melting at the current value (average current value Im) is preset, and when the average current value Irn is set with the current adjustment dial, tr.

tnl Ip v IQ +±8. Values such as -117 were not automatically adjusted to obtain the required current value. Here, the base current is set to a sufficiently lower value than the peak current.

However, when welding is performed using this consumable electrode type pulse arc welding machine, as shown in Fig. 1 (B), the arc has a strong straightness during the peak and flow, and the arc 1 is caused by lightning and the pole wire 2 However, when the base current is applied, the influence of the magnetic force due to the arc current ia flowing through the base metal 3 is stronger than the straightness of the arc, and therefore the arc 1 is bent, causing a so-called magnetic blowing phenomenon. The extent to which this arc is bent increases in the low current region # where the pace time tB is long.

This magnetic blow phenomenon does not cause much damage when welding flat plates, but when welding fillet welds, the arc fluctuates when the base current is applied, making it easy to break the arc, making stable welding impossible. An object of the invention is to provide a consumable electrode type pulse arc welding machine that can always perform stable welding even in a low current range with less arc disturbance caused by magnetic blowing.

[Summary of the Invention] The following countermeasures can be considered based on the occurrence of magnetic blow described above.

(a) Increase pulse frequency and pace time 1. to prevent the arc from stretching.

(b) Increase the base current 1B to strengthen the straightness of the arc.

(e) Increase the amplitude of the base current IB to strengthen the straightness of the arc at the peak of the amplitude.

In order to implement these measures, the present invention (1) increases the pulse frequency with respect to the standard pulse current waveform, shortens the pulse width tP to keep the average current value Im the same, or lowers the peak current IP; a first switching means for changing each setting value as shown in FIG.

(11) Base current i for standard pulse current waveform
A second switching means for changing the base current setting value IB so as to increase m.

G11l Base current i for standard pulse current waveform
Switching means of fang 3 that changes the hysteresis width ±β of on/off control so as to increase the amplitude of n.

This is a consumable electrode type pulse arc welding machine characterized by comprising at least one of the above.

[Embodiment of the Invention] FIG. 2 shows a block diagram of an embodiment of the present invention.

4: DC power supply, 5: pace current control transistor, 6:
is a peak current control transistor, 7.8 is a transistor drive circuit, 9 is a base current smoothing reactor, 10 is a peak current smoothing reactor, 11 is a diode that allows flywheel current to flow when transistor 5 is off, 12 is transistor 6's 13 is a shunt resistor; 14 is a current detection circuit; 15 is a base current setter; 16 is a peak current setter; 17 is a pace time setter; 18 is a peak time setter; The base current control signal generation circuit compares the detection signal of the current detection circuit 14 with the peak current setting value signal of the peak current setter 16 when the base current is flowing, and generates a control signal for controlling the transistor 6 on and off. 21 is base time setting device 1
An analog switch 22 is turned on only when the base current is in response to the signal from the peak time setter 18 and transmits the pace current control signal to the transistor drive circuit 7, and 22 is turned on only when the peak current is in response to the signal from the peak time setting device 18 to control the peak current. This is an analog switch that transmits a signal to the transistor drive circuit 8.

E' + Ex is the DC voltage Vl to the base current setting device 15.
A power supply that supplies lV2 (Vt <'h), Sl is its changeover switch, Es l R4 is a t source that supplies DC voltage Vs + Va (Vs pe4) to the peak current setting device 16, Ss is its changeover switch, Es + Es is the DC voltage V+t, Va (V
s > Vs), S4 is its changeover switch, R7t Ks is the DC voltage V to the peak time setting device 18.
t, a power supply supplying Vs (V7 > Vs), S
s is the changeover switch, R4+Ra is the resistance for setting the hysteresis width of the base current control signal generation circuit 19 (R4>
Rs) and St are the changeover switches, and the changeover switches 81 to S8 are operated in conjunction with each other.

Base current setting device 15 and base current control signal generation circuit 1
An example of 90 circuits is shown in FIG.

2 is a potentiometer constituting the base current setting device 15, which divides the DC voltage v1t or v2 to generate a base current set value signal. Base current control signal generation circuit 1
9 is OP amplifier A and resistor R.

~Hysteresis converter vertical leg consisting of Rs,
A base current setting device 15 is connected to the inverting input terminal of OP amplifier A.
The difference between the base current set value signal and the current detection signal from the current detection circuit 14 is input, and the voltage obtained by dividing the output voltage of the OP amplifier A by resistor R4 or Rs and resistor R3 is applied to the non-inverting input terminal. It will be done. Here, the output voltage of the OP amplifier A is the base current L centered around the base current set value In.
From LOW to Hl gh at the upper limit of B, the base current l
When the lower limit value of B changes from Hlgh to LOW, it is configured by a hysteresis comparator.

The base time setter 17 and the peak time setter 18 are rectangular wave generators that operate alternately, and the length of each generated rectangular wave changes depending on the voltage supplied from the DC power supplies E5 to E8.

This welding machine uses selector switches 81 to SL during normal welding.
1 in the position shown in the figure. In this case, as mentioned in the explanation of FIG. 1 (4), at the peak time tr, the peak current control transistor 6 is controlled on/off so that the peak current iP becomes tP=I,±a, and the pace time The base current control transistor 5 is controlled on/off so that the base current in becomes 1B=IB±β, and the same current value ( Welding is performed under appropriate conditions such that the amount of wire melting at Im) is maximized.

Next, if the arc tends to become unstable due to magnetic blowing with the standard Norms current waveform, such as in fillet welding, switch the selector switches 81 to S8 to the opposite position from the position shown in the figure. use. In this state, peak current setting device 1
6. The DC voltages supplied to the base time setting device 17 and the peak time setting device 18 are Va + Vs + Vy, respectively.
By decreasing from V4 to Va + Vs,
Compared to the standard pulse current waveform, the pace time tnt and peak time tp are shorter, and the peak current and current setting value Ip are shorter.
As a result, the pulse frequency increases while the average current value Im remains the same, and the countermeasure (IL) described above is executed.

Also, the DC voltage supplied to the base current setting device 15 is v
By increasing from l to v2, the pace current setting value IB increases with respect to the standard pulse current waveform, and the above (b)
The countermeasures described in Section 2.1 are implemented.

Furthermore, the hysteresis width setting resistor of the base current control signal generation circuit 19 is switched from R4 to Rs, and the resistance value becomes small, so that the amplitude (hysteresis width) ±β of the base current is changed from the standard pulse current waveform. If the force is large, the countermeasures in item (e) above will be implemented.

This suppresses the elongation of the arc at the base current and strengthens the straightness of the arc, so that disturbances in the arc due to magnetic blowing are reduced even in the low current range.

Any one of the measures listed in (8) to (c) above may be taken.
Although it is possible to obtain the effect of increasing the hysteresis, there are limits to increasing the pulse frequency and increasing the hysteresis width, so if you want to achieve a sufficient effect, there are two It is best to use the above measures together.

[Effects of the Invention] As described above, the present invention can be applied to ordinary C.
It is effective in preventing arc disturbances caused by magnetic blowing, which are likely to occur in pulsed arc welding, which has a long bare arc length compared to O2 arc welding, etc., and even in fillet welding, etc., which is difficult to weld with a standard pulsed current waveform, the changeover switch can be used. Stable welding can be performed by changing the setting values.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the pulse current waveform and arc shape in consumable electrode type pulsed arc welding, Figure 2 is a block diagram showing an embodiment of the present invention, and Figure 3 is the base current setting device 15 in Figure 2. 2 is a detailed diagram of the base current control signal generation circuit 19. FIG. 5: Transistor for base current control, 6: Transistor for peak current control, 7, 8:) transistor drive circuit, 14: Saving circuit, 15: Base current setting device, 1
6: Peak current setting device, 17: Base time setting device, 1
8: Peak time setting device, 19: Base current control signal generation circuit 20: Peak current control signal generation circuit, 21: Analog switch for base time control, 22: Analog switch for peak time control, El r R2: For base current setting Power supply, Es + R4: Power supply for peak current setting,
Et r Es: Peak time setting power supply, R41R8
: hysteresis width setting resistor, S4, 53 pss: changeover switch corresponding to the first changeover means, S changeover switch corresponding to the second changeover means, S2 changeover switch corresponding to the third changeover means. Figure 3 15 1q

Claims (1)

[Claims] a base current control transistor, a peak current control transistor, and a control signal generating means for controlling on/off the base current control transistor so that the base current value is within a predetermined hysteresis width centered on the base current setting value; A control signal generating means for controlling the peak current control transistor on and off so that the peak current value is within a predetermined hysteresis width centered on the peak current setting value, and a welding machine output current having a predetermined pulse frequency and pulse width. In a consumable electrode type pulse arc welding machine comprising means for controlling the time for supplying a control signal to the drive circuit of each of the transistors so as to obtain a pulsed current waveform, the pulse frequency is increased relative to a standard pulsed current waveform, and A first switching means that shortens the pulse width to make the average current value the same or changes each setting value to lower the peak current value, and increases the base current value with respect to the standard pulse current waveform. At least one of the second switching means for changing the base current setting value as shown in FIG. ”
Consumable electrode type pulse arc welding machine characterized by being equipped with a solenoid