JPH11104829A - Arc length control method of pulse arc welding and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness of arc length control to a variation in an arc length. SOLUTION: In the arc length control method of pulse arc welding by which a peak current Ip and a Base current Ib are made alternately flow to a consumable electrode by switching from the peak current to the base current after a peak period Tp set beforehand and welding is conducted, by detecting an instantaneous value Vd of welding voltage at a sampling intervals Tm set beforehand to be shorter than a base period Tb, by integrating by every interval and comparing a welding voltage set value Vsd and a welding voltage detected value Vdd from a starting time of a peak period Tp, by switching from the base current Ib to the peak current Ip at the timing a detection welding voltage integrated value Vi is smaller than a set welding voltage integrated value Vss, at the timing a pulse period T completes one period only, the arc length is reset when an arc length is fluctuated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a consumable electrode (hereinafter referred to as a consumable electrode).
The present invention relates to an arc length control method and apparatus for pulse arc welding in which a constant current is fed at a constant speed and a pulse current is supplied to control the arc length.

According to the present invention, the arc length of a pulse arc welding machine is controlled at high speed, and when the arc length changes due to a change in the distance between a tip and a workpiece to be welded due to hand shake of a welding operator or other disturbance, the stability of the arc can be improved. It is an invention related to a control method and a device for improving.

[Prior art]

FIG. 1 is a diagram for explaining a control method of a welding current output by a conventional welding device. Since the wire is fed at a constant speed, the average value of the welding current is controlled to increase or decrease the wire melting speed in order to control the arc length. The welding current of pulse arc welding has a peak current value I
The current of p and the current of the base current value Ib are applied alternately and repeatedly in the cycle of the peak period Tp and the base period Tb, respectively.

In the control method of the welding current shown in FIG. 1, the average value of the welding current is changed by increasing or decreasing the pulse frequency f to increase or decrease the wire melting speed. Figure (A)
Means that the pulse frequency f = f1 is higher than the pulse frequency f = f2 in FIG.
= Ia1 is larger than the average value Ia = Ia2 of the welding current in FIG. It should be noted that the pulse periods T in FIGS.
= 1 / f1 and T2 = 1 / f2.

Conventionally, in order to stabilize the arc, arc length control is performed by controlling a pulse frequency f, a pulse width (peak period) Tp, a peak current value Ip, or a base current value Ib.

Hereinafter, in pulse arc welding using a welding power source having a constant current characteristic in which the set value of the peak current value Ip and the set value of the base current value Ib are kept constant, the welding current is changed by controlling the pulse frequency f. A conventional arc length control method and apparatus will be described.

FIG. 2 shows a case where welding is performed by energizing the pulse currents of the peak current value Ip, the base current value Ib, the peak period Tp and the base period Tb repeatedly and periodically without considering the arc length control. FIG. 4 is a diagram illustrating a relationship among a voltage V, a welding current I, and an average arc length L. Hereinafter, with reference to FIG. 2, a description will be given of an arc length control method according to the related art when the vehicle passes through a step. Since a current having a constant current characteristic is applied, the welding current value does not change before and after passing through the step. Even after passing through the step, the output current value does not directly change from the characteristics of the power supply, unlike a welding power supply having a constant voltage characteristic, so that the melting speed of the wire does not change. Therefore, the arc length changes by the height of the step from the arc length L1 before the step change to the arc length L2 after the step change. At this time, the average value Va of the welding voltage (hereinafter, referred to as the average welding voltage value) increases from the average welding voltage value Va1 before the step change to the average welding voltage value Va2 after the step change, so that the average welding voltage Va is , Are used as parameters indicating changes in the arc length.

Therefore, in the prior art, as shown in FIG. 3 described later, a detected welding voltage smoothing signal Vda obtained by detecting and smoothing an instantaneous value of the welding voltage and a welding voltage in which a welding voltage value corresponding to the arc length is set. By comparing the voltage setting signal Vs and the difference setting / detection welding voltage comparison signal Cm2, the pulse frequency f is controlled to change the wire melting speed, and the set welding voltage value and the detected welding voltage value are compared. It is controlled to be equal.

FIG. 3 is a block diagram of a conventional pulse arc welding apparatus for controlling an arc length by controlling a pulse frequency by supplying a pulse current. Hereinafter, FIG.
, A conventional arc length control method for a welding device will be described. In the figure, a pulse welding power source PS inputs a commercial power source AC and outputs welding power to a wire 1 and a workpiece 2. The wire feed speed setting circuit WS outputs a wire feed speed setting signal Ws of the set wire feed speed to the wire feed motor WM.

The welding voltage instantaneous value detection circuit VD detects an instantaneous value of the welding voltage and outputs a welding voltage instantaneous value detection signal Vd. The detected welding voltage smoothing circuit VDA smoothes the instantaneous value of the welding voltage and outputs a detected welding voltage smoothed signal Vda. The welding voltage setting circuit VS outputs a welding voltage setting signal Vs. The setting / detection welding voltage comparison circuit CM2 receives the detection welding voltage smoothing signal Vda and the welding voltage setting signal Vs as inputs and outputs a setting / detection welding voltage comparison signal Cm2.

The voltage / frequency conversion circuit VF receives the setting / detection welding voltage comparison signal Cm2 and outputs a frequency control signal Vf corresponding to the pulse frequency f. The pulse width setting circuit TP outputs a pulse width setting signal Tp of the set pulse width. The pulse frequency / width control circuit DF receives the frequency control signal Vf and the pulse width setting signal Tp, and outputs a pulse frequency / width control signal Df of the set pulse width in synchronization with the pulse frequency of the frequency control signal Vf. I do.

The base current value setting circuit IBS outputs a base current value setting signal Ibs, and outputs a peak current value setting circuit IPS.
S outputs a peak current value setting signal Ips. peak·
The base current value switching circuit SW1 switches between the peak current value setting signal Ips and the base current value setting signal Ibs to output a peak / base current value switching signal Sw1. This peak
The base current value switching signal Sw1 outputs a peak current value setting signal Ips during the peak period Tp in synchronization with the frequency of the pulse frequency / width control signal Df, as shown in an elapsed time t in FIG. , And outputs a base current value setting signal Ibs during the base period Tb.

The setting / detection current comparison circuit CM1 receives the welding current detection signal Id and the peak / base current value switching signal Sw1 and outputs a welding current control signal Cm1 representing the difference between the signals. It outputs to a pulse welding power source PS including a circuit to control the welding current value.

The welding conditions are set by the following circuit. The welding voltage setting circuit VS sets the output (arc) voltage, the pulse width setting circuit TP sets the pulse width, the peak current value setting circuit IPS sets the peak current value, and the base current value setting circuit IBS sets the base current. Set the value.

FIG. 4 is a diagram showing the relationship between each operation signal of the conventional welding device shown in FIG. 3 and the elapsed time t. 5A shows a welding voltage instantaneous value detection signal Vd, FIG. 5B shows a detected welding voltage smoothing signal Vda and a welding voltage setting signal Vs, and FIG. 5C shows a frequency control signal Vf. FIG. 3D shows the pulse frequency / width control signal Df. FIG. 7E shows a peak-base current value switching signal Sw1 output from the peak-base current value switching circuit SW1 to which the pulse frequency / width control signal Df is input. FIG. 7F shows the welding current detection signal Id.

[0030]

The above-mentioned conventional arc length control method has the following problems. In order to improve the responsiveness of the arc length control with respect to variations in the arc length, in a conventional welding apparatus using a feedback control circuit for an analog signal, the welding voltage instantaneous value detection signal Vd is reduced directly or by reducing the smoothness. When input to the setting / detection welding voltage comparison circuit CM2 for feedback control, hunting occurs. Therefore, the welding voltage instantaneous value detection signal Vd is smoothed by an analog smoothing circuit so as not to cause hunting and fed back.

FIG. 5 shows the time t1 of the elapsed time t during welding.
FIG. 7 is a diagram showing changes in an average welding voltage value Va, an average welding current value Ia, and an average arc length La corresponding to an arc length when the arc passes through a position having a step. Figure (A)
Is the response of the change of the instantaneous value of the welding voltage corresponding to the pulse current waveform and the change of the average welding voltage value Va corresponding to the arc length when passing through a stepped position at time t1 of the elapsed time t during welding. FIG. 6B is a diagram showing a temporal change of the pulse current corresponding to the controlled pulse frequency f (pulse period T), and FIG. 6C is a diagram showing the average arc length La. It is a figure showing the response of a change.

At the time t1 of the elapsed time t during welding, when passing through a stepped position, the arc length is changed from the arc length L1 before the step change to the arc length after the step change, as shown in FIG. L2, the frequency control signal Vf decreases the pulse frequency f by the operation of the welding apparatus of FIG. 3 described above, and therefore, as shown in FIG.
1 / f becomes longer, the average welding current value Ia gradually decreases, and as shown in FIG. 4C, the average arc length La gradually decreases, and at time t5, the arc before the step change changes. Length L
Return to 1.

As described above, in the conventional welding apparatus using the analog signal feedback control circuit, since the welding voltage instantaneous value detection signal Vd is smoothed by the analog smoothing circuit so as not to hunt, there is a step. The time required for the arc length L2 immediately after passing through the position to return to the arc length L1 before the step change becomes longer, resulting in poor responsiveness.

FIG. 6 is a diagram showing a change in appearance of a weld bead when welding is performed by a conventional arc length control and an arc passes through a step. As shown in the figure, since the arc length increases after passing through the step, the range in which the workpiece is subjected to the arc heat is widened, and the bead width W is widened. At this time, in the conventional apparatus, since the arc length La cannot be quickly restored, a portion having a wide bead width becomes long. As a result, in the conventional apparatus, the period during which the weld bead width W is widened becomes long, the change in the penetration shape becomes large, and the uniformity of the welding result is reduced.

In order to solve these problems, the arc length control method of pulse arc welding of the prior application (Japanese Patent Application No. 8-110259) filed by the present applicant detects the instantaneous value of the welding voltage and smoothes it. Instead, calculate the average voltage value for each cycle or short cycle of the pulse current, compare it with the set value of the set welding voltage, control the base period of the next cycle by the comparison value, and The present invention has made it possible to realize an arc length control method and apparatus for returning an arc length at a high speed without causing hunting when fluctuates.

The prior application filed by the applicant (Japanese Patent Application No. 8-1)
In the arc length control method of pulse arc welding of 10259), when one cycle T of the pulse current ends, the base period Tb of the next cycle is calculated and controlled. The time required to return the head is
Although high speed without hunting, a plurality of pulse periods T were required. On the other hand, according to the arc length control method of the pulse arc welding of the present invention, when the arc length fluctuates, the arc length can be restored when only one pulse cycle T ends.

[0040]

According to the present invention, there is provided a method for controlling an arc length of pulsed arc welding, comprising the steps of:
Later, switching from the peak current Ip to the base current Ib,
In the arc length control method of pulse arc welding in which a peak current and a base current are repeatedly applied to a consumable electrode to perform welding, an instantaneous value Vd of a welding voltage is detected at a predetermined sampling interval Tm shorter than a base period Tb, From the start of the peak period Tp, the welding voltage set value Vsd and the welding voltage detection value Vdd are integrated and compared at the sampling interval Tm, and the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss. This is a method of controlling the arc length of pulse arc welding in which the base current Ib is switched to the peak current Ip at the time when the arc length fluctuates so that the arc length is restored when the arc length fluctuates.

According to the arc length control method of pulse arc welding, the peak current Ip is switched to the base current Ib after a preset peak period Tp, and the peak current and the base current are repeatedly supplied to the consumable electrode to perform welding. In the arc length control method of pulse arc welding, the instantaneous value Vd of the welding voltage is detected at a preset sampling interval Tm shorter than the base period Tb, and the welding voltage set value Vsd and the welding voltage are set from the start of the peak period Tp. Voltage detection value Vdd
Are integrated at the above-mentioned sampling interval Tm and compared. When the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss, the base current Ib is switched to the peak current Ip, so that the arc length is reduced. This is an arc length control method of pulse arc welding for restoring the arc length when it fluctuates.

According to a second aspect of the present invention, there is provided an arc length control method for pulse arc welding, wherein a peak period completion determining step for determining whether the peak period Tp during welding has reached a set peak period, and a step for determining whether the peak period has not reached the peak period. Is a peak current output step that outputs a peak current Ip of a set current value and repeats until a peak period is reached, and a base current that outputs a base current Ib of a set current value when the set peak period has been reached. When the output step and the completion of the base period are not determined, the base current of the set current value is output and repeated until the completion of the base period is determined. When the completion of the base period is determined, the next peak period is performed. A repetitive start step to start and an instantaneous value of the welding voltage detected at a preset sampling interval Tm shorter than the base period Tb Te, from the start of the peak period, the welding voltage set value Vsd and the welding voltage detected value Vdd, compared by integrating the sampling interval Tm, detecting welding voltage integrated value Vi
Is determined to be smaller than the set welding voltage integrated value Vss, a base period completion determining step of determining completion of the base period, and a set peak period Tp in which the peak current Ip is supplied until the supply command signal Ts ends. And a base period Tb in which the base current Ib is applied after the elapse of the peak period Tp until the base period completion signal Tbk is output.

According to a third aspect of the present invention, there is provided an arc length control method for pulse arc welding, wherein a peak period completion determining step (whether the peak period Tp has been reached is determined during welding in which the energization command signal after the start of welding is continued). ST3) and a peak current output step (ST4) for outputting a peak current value Ip when the set peak period Tp has not been reached,
The sampled welding voltage detection value Vdd = Vddm is added to the detected welding voltage integrated value Vdd1 + Vdd2 +... + Vdd (m-1) integrated up to the previous (m-1) th time, and the added detected welding voltage integrated value Vi is added. , And a welding voltage detection value integration step (ST5), and a set welding voltage integration value Vsd1 + Vsd2 +.
(m-1), and a welding voltage set value integrating step (ST6) of storing the added set welding voltage integrated value Vss,
The detected welding voltage integrated value Vi is compared with the set welding voltage integrated value Vss. If the detected welding voltage integrated value Vi exceeds the set welding voltage integrated value Vss, the process returns to the peak period completion determination step (ST3). The integrated detection / set welding voltage comparison step (ST7) is repeated, and when the set peak period Tp is reached, the base period Tb is started, the base current value Ib is supplied, and the detected welding voltage integrated value Vi is increased. When the current value becomes smaller than the set welding voltage integrated value Vss, the base period Tb ends and a base period execution step (ST8) starts the next peak period Tp. Until the energization command signal Ts ends. A set peak period Tp for supplying the peak current Ip, and a base period for supplying the base current Ib after the elapse of the peak period Tp until the base period completion signal Tbk is output. A pulse arc welding method repeating the scan period Tb.

According to a fourth aspect of the present invention, there is provided an arc length control method for pulse arc welding, wherein the number of times of the clock signal Ck input during the peak period Tp is counted during the welding in which the current supply command signal after the start of welding is continued. Period count value Tpc
Is a peak period completion determining step (ST3) of determining whether the number has reached the set number of times of the set peak period Tp.
And when the peak period count value Tpc has not reached the set number of peak periods Tp, the control current digital signal having the value of the peak current value Ip as the value of the control current digital signal Icd and the value of the peak current value Ip A peak current output step (ST4) for outputting the signal Icd to the control current D / A conversion circuit DA1 and, for each clock signal Ck, a welding voltage detection value Vdd is read from the detection welding voltage A / D conversion circuit AD1 and pulsed. The welding voltage detection value Vdd = V sampled at the time of the m-th clock signal Ck during the period T
ddm is added to the detected welding voltage integrated value Vdd1 + Vdd2 +... + Vdd (m-1) integrated up to the previous (m-1) th time, and the added detected welding voltage integrated value Vi is stored. Integration step (ST5) and clock signal C
For each k, the welding voltage set value Vsd is read from the set welding voltage A / D conversion circuit AD2, and the welding voltage set value Vsd = Vsdm sampled at the m-th clock signal Ck during the pulse cycle T is set to 1 + Vsd1 + Vsd2 + Vsd1 + Vsd2
sd (m-1), and the set welding voltage integrated value Vss
Step for integrating welding voltage set value (ST6)
And the detected welding voltage integrated value Vi for each clock signal Ck.
Is compared with the set welding voltage integrated value Vss. If the detected welding voltage integrated value Vi exceeds the set welding voltage integrated value Vss, the process returns to the peak period completion determination step (ST3) to repeat the execution. Set welding voltage comparison step (S
T7) and when the set peak period Tp has been reached, the base period is started, the base current value Ib is supplied, and the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss. Then, the base period Tb is ended, and the next peak period Tp is started.
8) until the current supply command signal Ts ends, a set peak period Tp in which the peak current Ip is supplied, and the base period completion signal T after the elapse of the peak period Tp.
This is a pulse arc welding method that repeats a base period Tb during which a base current Ib is supplied until bk is output.

The welding apparatus according to claim 5 receives the set welding voltage digital signal Vsd and the detected welding voltage digital signal Vdd, and sets a peak period T at each sampling interval Tm.
From the start of p, the welding voltage set value Vsd and the welding voltage detection value Vdd are integrated and compared. When the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss, the base period completion signal Tbk Period completion determination circuit TB that outputs
N, the set peak current Ip is output during the set peak period Tp, the set base current Ib is supplied after the elapse of the peak period Tp to start the base period Tb, and the base period completion signal Tbk is output. And a peak period setting circuit TPB for ending the base period Tb, until the energization command signal Ts ends.
A set peak period Tp and a peak period Tp
This is a pulse arc welding apparatus that repeats a base period Tb in which a base current Ib is applied after the elapse of the period until the base period completion signal Tbk is output.

In the welding apparatus according to the present invention, the set welding voltage digital signal Vsd and the detected welding voltage digital signal Vdd are inputted, and the peak period T is set at every sampling interval Tm.
From the start of p, the welding voltage set value Vsd and the welding voltage detection value Vdd are integrated and compared. When the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss, the base period completion signal Tbk Period completion determination circuit TB that outputs
N, the set peak current Ip is output during the set peak period Tp, the set base current Ib is supplied after the elapse of the peak period Tp to start the base period Tb, and the base period completion signal Tbk is output. Then, a peak period setting circuit TPB ending the base period Tb and a pulse width setting signal Tp are input to output a peak current value setting signal Ips set for the set peak period Tp.
A peak-base current value control circuit IPB circuit that outputs a base current value setting signal Ibs during a base period Tb, and a control current analog signal Id that receives a control current digital signal Icd.
Welding current digital / analog conversion circuit D that outputs ca
A1; a welding current detection signal Id; and a control current analog signal Ica. A setting / detection current comparison circuit CM1 for controlling a welding current value by outputting a welding current control signal Cm1 of the difference to a pulse welding power source PS. And the energization command signal T
Until s ends, the set peak period Tp for supplying the peak current Ip and the base current Ip until the above-described base period completion signal Tbk is output after the elapse of the peak period Tp.
This is a pulse arc welding apparatus that repeats a base period Tb for energizing b.

According to a seventh aspect of the present invention, the base period completion determination circuit TBN of the fifth or sixth aspect receives the set welding voltage digital signal Vsd and outputs a sampling interval Tm.
Each time, from the start of the peak period Tp, the set voltage detection value Vsd is integrated, and the set welding voltage integration storage circuit SVI for storing the integrated set welding voltage integrated value Vss and the detected welding voltage digital signal Vdd are input. Then, at each sampling interval Tm, the welding voltage detection value Vdd is integrated from the start of the peak period Tp, and the integrated detected welding voltage integration value V
The detected welding voltage integrated storage circuit DSI for storing i is compared with the detected welding voltage integrated value Vi and the set welding voltage integrated value Vss, and the detected welding voltage integrated value Vi is set to the set welding voltage integrated value Vss.
The pulse arc welding apparatus is an integrated detection / setting welding voltage comparison circuit DSC that outputs a base period completion signal Tbk when the value becomes smaller than the above.

[0051]

FIG. 7 is a block diagram showing an embodiment of a welding apparatus for performing the arc length control method of pulse arc welding according to the present invention. The difference between the arc length control method of the present invention and the conventional arc length control method is as follows.

In the above-described conventional arc length control method, the detected welding voltage smoothing signal Vda is obtained by detecting and smoothing the instantaneous value of the welding voltage using an analog signal feedback control circuit.
And the welding voltage setting signal Vs in which the welding voltage value corresponding to the arc length is set. The pulse frequency f is increased or decreased by the difference setting / detection welding voltage comparison signal Cm2 to change the average welding current value Ia. In this way, the arc length is controlled.

In contrast to the prior art described above, the arc length control method of the present invention uses a software control circuit or a hardware control circuit that performs the function of the peak-to-base current control circuit IC. The instantaneous value Vd is detected at a preset sampling interval Tm shorter than the base period Tb, and from the start of the peak period Tp, the welding voltage set value Vsd and the welding voltage detection value Vdd are integrated at the sampling interval Tm. By switching from the base current Ib to the peak current Ip when the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss, the arc length is restored when the arc length changes. The arc length is controlled. Hereinafter, a circuit different from FIG. 3 will be described.

The instantaneous welding voltage detection circuit VD detects an instantaneous value of the welding voltage and outputs a welding voltage instantaneous value detection signal Vd. The detected welding voltage analog / digital conversion circuit (hereinafter, referred to as A / D conversion circuit) AD1 receives the welding voltage instantaneous value detection signal Vd and receives the detected welding voltage digital signal V1.
Output dd. The set welding voltage A / D conversion circuit AD2 is
A welding voltage setting signal Vs is input to output a set welding voltage digital signal Vsd.

The peak-base current control circuit IC is constituted by a software control circuit or a hardware control circuit for executing the function of the circuit IC. The function of the software control circuit is executed according to the procedures of the flowcharts (1/2) and (2/2) shown in FIGS. Also,
The hardware control circuit includes a circuit shown in FIG. 13 described later.

The welding current digital / analog conversion circuit (hereinafter referred to as D / A conversion circuit) DA1 receives the control current digital control signal Icd and outputs the control current analog signal Ica. The setting / detection current comparison circuit CM1 receives the welding current detection signal Id and the control current analog signal Ica, outputs a welding current control signal Cm1 of the difference, and outputs, for example, a pulse welding power supply including a PWM control inverter circuit. Output to PS to output welding current value.

[0061]

8 and 9 are block diagrams of a welding apparatus for carrying out the arc length control method of the present invention shown in FIG. 7, which is a flowchart for executing the function of a peak-base current control circuit IC by software (1/2). ) And (2/2). Hereinafter, an arc length control method of pulse arc welding according to the present invention will be described with reference to FIG. 8 and FIG. 9 in accordance with the operation of the n-th pulse cycle after the start of welding. (1) Initial setting step (ST1) a. A peak period (pulse width) Tp, a peak current value Ip, and a base current value Ib are set. b. The detected welding voltage integrated value Vi obtained by integrating the count value Tpc of the peak period counter TPC (hereinafter referred to as the peak period count value Tpc), the welding voltage detected value Vdd, and the set welding voltage integrated value Vss obtained by integrating the welding voltage set value Vsd. Reset. c. The cycle of the output signal of the control interrupt timer (hereinafter referred to as clock signal Ck) is set to 100 μs. These settings are operations performed before the start of welding. In addition,
The base period Tb is determined in a step described later.

The operation after the start of welding will be described below. (2) Control Interrupt Determination Step (ST2) Wait for a period until the clock signal Ck reaches 100 μs, and determine the presence or absence of a control interrupt. The following digital circuit operates every 100 μs.

(3) Peak Period Completion Determination Step (ST)
3) The peak period counter TPC indicates the peak period Tp during welding where the energization command signal Ts after the start of welding is continued.
Is counted to determine whether or not the peak period count value Tpc has reached the set number of times for the set peak period Tp.

(4) Peak current output step (ST4) a. When the peak period count value Tpc has not reached the set number of peak periods Tp, the value of the peak current value Ip is used as the value of the control current digital signal Icd. b. The peak period count value Tpc is incremented (added) by one. c. The control current digital signal Icd having the value of the peak current value Ip is output to the control current D / A conversion circuit DA1.

(5) Step of integrating welding voltage detection values (S
T5) a. The welding voltage detection value Vdd is read from the detection welding voltage A / D conversion circuit AD1 for each clock signal Ck. At the time of the description, the clock signal C during the n-th pulse period T
k, for example, the welding voltage detection value Vdd sampled at the time of the m-th clock signal Ck. b. The welding voltage detection value Vdd = Vddm sampled at the m-th clock signal Ck at the above timing is
It is added to the detected welding voltage integrated value Vdd1 + Vdd2 +... + Vdd (m-1) integrated up to the previous (m-1) th time, and the added detected welding voltage integrated value Vi is stored. The detected welding voltage integrated value Vi is expressed as Vi = (Vdd1 + Vdd2 +... + Vdd (m
-1)) + Vddm.

(6) Step of integrating welding voltage set values (S
T6) a. The welding voltage set value Vsd is read from the set welding voltage A / D conversion circuit AD2 for each clock signal Ck. At the time of the description, the clock signal C during the n-th pulse period T
k, for example, the welding voltage set value Vsd sampled at the time of the m-th clock signal Ck. b. The welding voltage set value Vsd = Vsdm sampled at the time of the m-th clock signal Ck at the above timing is
The set welding voltage integrated value Vss is added to the set welding voltage integrated value Vsd1 + Vsd2 +... + Vsd (m-1) integrated up to the previous (m-1) th time, and the added set welding voltage integrated value Vss is stored. The set welding voltage integrated value Vss is represented by Vss = (Vsd1 + Vsd2 +... + Vsd (m
-1)) + Vsdm.

(7) Integrated detection / set welding voltage comparison step (ST7) For each clock signal Ck, the detected welding voltage integrated value Vi is compared with the set welding voltage integrated value Vss to set the detected welding voltage integrated value Vi. If it exceeds the welding voltage integrated value Vss,
Returning to step ST2, the execution is repeated.

(8) Base Period Execution Step (ST8) a. When the peak period count value Tpc has reached the set peak period Tp in the above-described peak period completion determination step (ST3), the base period is started,
The value of the base current value Ib is set as the value of the control current digital signal Icd. b. In the base period Tb, in the integrated detection / set welding voltage comparison step (ST7), the detected welding voltage integrated value Vi is compared with the set welding voltage integrated value Vss for each clock signal Ck, and the detected welding voltage integrated value is calculated. If Vi exceeds the set welding voltage integrated value Vss, step ST
Return to 2 and repeat the execution. c. In the base period Tb, in the integrated detection / set welding voltage comparison step (ST7), the detected welding voltage integrated value Vi is compared with the set welding voltage integrated value Vss for each clock signal Ck, and the detected welding voltage integrated value is calculated. When Vi becomes smaller than the set welding voltage integrated value Vss, the process proceeds to the next count value reset step ST9, and then ends the base period Tb and starts the next peak period Tp.

(9) Step of resetting count value (S
T9) The set welding voltage integrated value Vss obtained by integrating the peak period count value Tpc and the welding voltage set value Vsd and the detected welding voltage integrated value Vi obtained by integrating the welding voltage detection value Vdd are reset. (10) Control Stop Judgment Step If the energization command signal is stopped, the procedure ends.

FIG. 10 shows that the welding voltage set value Vsd and the welding voltage detection value Vdd are changed every 100 [μs] of the clock signal Ck in the n-th pulse cycle after the start of welding, from the start of the peak period Tp. It is a welding voltage setting / detection sampling diagram sampling m times.

The welding voltage set values Vsd sampled from the first time to the m-th time at the start of the peak period Tp are respectively Vsd1, Vsd2,..., Vsd (m-1) and Vsd
m, and the sampled welding voltage detection values Vdd are Vdd1, Vdd2,..., Vdd (m-1) and Vddm, respectively, indicated by black circles. The welding voltage set value Vsd is equal to the peak period Tp.
And the base period Tb have the same value, but the welding voltage detection value Vdd is a large value in the peak period Tp and a small value in the base period Tb.

FIG. 11 shows the welding voltage indicating the lapse of time between the set welding voltage integrated value Vss obtained by integrating the welding voltage set value Vsd sampled in FIG. 10 and the detected welding voltage integrated value Vi obtained by integrating the welding voltage detection value Vdd. It is a setting and detection integrated value comparison diagram.

Since the welding voltage set value Vsd has the same value in both the peak period Tp and the base period Tb, the set welding voltage integrated value Vss increases with the same slope in both the peak period Tp and the base period Tb. However, the detected welding voltage integrated value Vi rises with a larger slope than the set welding voltage integrated value Vss during the peak period Tp, but becomes smaller than the set welding voltage integrated value Vss during the base period Tb. Therefore, at the time when the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss at the m-th integration from the start of the peak period Tp, the aforementioned base period execution step ST
As described in section c of FIG. 8, the base period Tb ends, and the next peak period Tp starts.

FIG. 12 is a diagram for explaining a control method of the welding current output by the welding device of the present invention. The welding device shown in the figure increases or decreases the base period Tbn at the time when the change in the arc length is detected, thereby changing the welding current value at that time to increase or decrease the wire melting speed. Figure (A)
Is that the base period Tbn = Tb1 is larger than the base period Tbn = Tb2 in FIG.
The value a = Ia1 is larger than the average value Ia = Ia2 of the welding current shown in FIG.

FIG. 13 shows a control circuit in which the peak-base current control circuit IC of the block diagram of the welding apparatus for implementing the arc length control method of the present invention is constituted by hardware.
The hardware peak-base current control circuit IC shown in FIG. 13 includes a base period completion determination circuit TBN, a peak period setting circuit TPB, and a peak-base current value control circuit IPB.
The operation of each circuit is as follows.

First, the base period completion determination circuit TBN shown in FIG. 13 will be described. The base period completion determination circuit TBN inputs the set welding voltage digital signal Vsd and the detected welding voltage digital signal Vdd sampled at the sampling interval Tm, and performs welding from the start of the peak period Tp at each sampling interval Tm. Voltage set value Vsd
And the welding voltage detection value Vdd is integrated and compared. When the detected welding voltage integration value Vi becomes smaller than the set welding voltage integration value Vss, a base period completion signal Tbk is output. The base period completion determination circuit TBN includes a set welding voltage integration storage circuit SVI that integrates and stores the welding voltage set value Vsd, a detection welding voltage integration storage circuit DSI that integrates and stores the welding voltage detection value Vdd, and a detected welding voltage. Integrated detection / set welding voltage comparison circuit DS that outputs base period completion signal Tbk when voltage integrated value Vi becomes smaller than set welding voltage integrated value Vss.
C.

The detected welding voltage integration storage circuit DSI integrates the detected welding voltage detected value Vdd = Vddm sampled at the time of the m-th clock signal Ck up to the previous (m-1) th time. Value Vdd1 + Vdd2 + ... + V
dd (m-1), and the added detected welding voltage integrated value Vi
Is stored. The set welding voltage integration storage circuit SVI is a set welding voltage integrated value Vsd1 + Vsd2 +... Obtained by integrating the welding voltage set value Vsd = Vsdm sampled at the time of the m-th clock signal Ck up to the previous (m-1) th time. + V
sd (m-1), and the set welding voltage integrated value Vss
Is stored.

Integrated detection / setting welding voltage comparison circuit DSC
Is the detected welding voltage integrated value Vi for each clock signal Ck.
And the set welding voltage integrated value Vss, and when the detected welding voltage integrated value Vi becomes smaller than the set welding voltage integrated value Vss, a base period completion signal Tbk is output.

The peak period setting circuit TPB outputs a peak period count signal Tpc for supplying the peak current Ip, and after the set peak period Tp, supplies the base current Ib and outputs the base period completion signal Tbk. Sometimes, the base period Tb ends.

The peak-base current value control circuit IPB circuit inputs the peak period count signal Tpc and outputs the set peak current value setting signal Ips for the set peak period Tp, and then sets the set peak current value signal Ips. After the elapse of the peak period Tp, the base period Tb is started, and the base current value setting signal Ibs is output until the base period completion signal Tbk is output.

The clock signal generation (Ck output) circuit
For example, a clock signal Ck having a period of 100 μs is generated. Each digital circuit described later operates at this timing. The AND circuit AND1 outputs the clock signal Ck while the welding start energization command signal Ts is being input. First, the peak period count value Tpc of the peak period counter TPC and the detected welding voltage integrated value Vi of the welding voltage detection value Vdd described later are reset.

The peak period counter TPC counts the number of clock signals Ck input during the peak period Tp, and counts the peak period count value T of the counted pulse period.
It is determined whether or not pc has reached the set number of samplings during the peak period Tp. This peak period counter TP
C indicates that the energization command signal Ts and the clock signal Ck at the start of welding are input to the AND circuit AND1 or that the energization command signal Ts continues and the clock signal Ck is output from the AND circuit AN1.
D1 and the base period complete signal Tbk is output to start counting from the peak period count signal Tbk.
PC is output, and when the set peak period Tp has elapsed, the counting is stopped and the peak period count signal Tpc is stopped. If the peak period count value Tpc has not reached the set number of peak periods Tp, a peak period count signal Tpc is output, and the peak period count value Tpc is set to one.
Only increment (addition).

When the peak period count value Tpc has reached the set peak period Tp, a peak period completion signal Tpk is output to a base current value storage circuit IPM described later.
The base period Tb starts.

The peak-base current value control circuit IPB
Peak current value storage circuit IPM and base current value storage circuit I
The circuit is composed of a BM and a control current digital signal output circuit ICD. The operation of each circuit is as follows. This peak-base current value control circuit IPB outputs the set peak current value setting signal Ips during the peak period Tp set by inputting the pulse width setting signal Tp. Next, when the peak period completion signal Tpk is input, the peak current value setting signal Ips is stopped to end the peak period Tp, and the set base current value setting signal Ibs is output to start the base period. Thereafter, when the base period completion signal Tbk is inputted, the base current value setting signal Ibs is stopped and the base period T
After b, the peak current value setting signal Ips is output again to start the peak period.

The peak current value storage circuit IBM stores the set peak current value Ip, and every time the peak period count signal Tpc is inputted, the peak current value control signal Ip
ps is output to the control current digital signal output circuit ICD. The base current value storage circuit IBM stores the set base current value Ib and controls the base current value signal Ibs from the input of the peak period completion signal Tpk to the input of the base period completion signal Tbk. Output to the current digital signal output circuit ICD.

Control current digital signal output circuit ICD
Converts the control current digital signal Icd of the peak current value setting signal Ips or the base current value setting signal Ibs into the control current D /
It outputs to the A conversion circuit DA1.

The base current value setting signal Ibs is a peak period count value Tpc of the peak period counter TPC, the set welding voltage integrated value Vss of the set welding voltage integrated storage circuit SVI, and the detected welding voltage of the detected welding voltage integrated storage circuit DSI. Reset with the integrated value Vi is performed.

In the welding apparatus having the above configuration, the peak current Ip having the set current value is supplied during the set peak period Tp, and the base period Tb is started when the peak period completion signal Tpk is input. Until the completion signal Tbk is input, the base current Ib of the set current value is applied to
The arc length is restored periodically. The welding device of this configuration
Until the energization command signal Ts ends, the peak period Tp during which the peak current Ip is energized, and the base current Ip after the elapse of the peak period Tp until the base period completion signal Tbk is output.
The base period Tb in which b is energized is repeated.

[0100]

FIG. 14 shows the welding voltage value, the average welding current value Ia and the average arc length corresponding to the arc length when the arc passes through a stepped position at time t1 of the elapsed time t during welding. FIG. 6 is a diagram showing a change La of the graph. FIG.
FIG. 9B is a diagram showing the response of a change in the instantaneous value of the welding voltage corresponding to the pulse current waveform when the arc passes through a stepped position at time t1 of the elapsed time t during welding;
FIG. 4 is a diagram showing a temporal change of the welding current Ia during the controlled base period Tbn, and FIG. 4C is a diagram showing the average arc length La.
FIG. 9 is a diagram showing the response of a change in the data.

At time t1 of the elapsed time t during welding, when the arc passes through a position with a step, the arc length is changed from the arc length L1 before the step change to the arc length L1 after the step change, as shown in FIG. Since it changes to the arc length L2, the base period Tb is increased by the base period completion signal Tbk by the operation of the welding apparatus shown in FIG. 8, FIG. 9 or FIG. 13, and as shown in FIG. The welding current value Ia sharply decreases, and the average arc length La rapidly decreases as shown in FIG. 4C, and returns to the arc length L1 before the step change at time t2.

FIG. 15 is a view showing a change in appearance of a weld bead when welding is performed by the arc length control of the present invention and an arc passes through a step. As shown in the figure, after passing through the step, the arc length is temporarily increased, the range in which the workpiece receives arc heat is widened, and the bead width W is widened. However, at this time, in the method and apparatus of the present invention,
As shown in FIG. 6, since the arc length La can be quickly restored in a shorter time than in the conventional apparatus, a portion having a wide bead width is shortened. As a result, in the method and the apparatus of the present invention, the period in which the weld bead width W is widened is short, the penetration shape is hardly changed, and the uniformity of the welding result is maintained.

In the arc length control method of the invention of the prior application filed by the present applicant, when one cycle T of the pulse current ends, the base period Tb of the next cycle is calculated and controlled.
The time required to restore the arc length when the arc length fluctuates is high speed without hunting,
A plurality of pulse periods T were required. On the other hand, according to the arc length control method of the pulse arc welding of the present invention, when the arc length fluctuates, the arc length can be restored when only one pulse cycle T ends.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a control method of a welding current output by a conventional welding device.

FIG. 2 is a diagram showing a case where welding is performed by energizing a pulse current of a peak current value Ip, a base current value Ib, a peak period Tp and a base period Tb periodically and repeatedly without considering arc length control; It is a figure which shows the time progress of the relationship of welding voltage V, welding current I, and arc length L.

FIG. 3 is a block diagram of a conventional pulse arc welding apparatus that controls a pulse length by supplying a pulse current and controlling a pulse frequency.

FIG. 4 is a diagram showing a relationship between each operation signal of the conventional welding apparatus shown in FIG. 3 and an elapsed time t.

FIG. 5 is a diagram showing an average welding voltage value Va, an average welding current value Ia, and an average arc length corresponding to an arc length when an arc passes through a stepped position at time t1 of elapsed time t during welding. It is a figure showing change of La.

FIG. 6 is a diagram showing a change in appearance of a weld bead when welding is performed by a conventional arc length control and an arc passes through a step.

FIG. 7 is a block diagram of an embodiment of a welding apparatus for implementing the arc length control method of the pulse arc welding according to the present invention.

FIG. 8 is a flowchart (1/2) of executing a function of a peak-base current control circuit IC by software in the block diagram of the welding apparatus for implementing the arc length control method of the present invention of FIG. 7; .

9 is a flowchart (2/2) of executing a function of a peak-base current control circuit IC by software in the block diagram of the welding apparatus for implementing the arc length control method of the present invention in FIG. 7; .

FIG. 10 is a graph showing the relationship between the welding voltage set value Vsd and the welding voltage detection value Vdd for each clock signal Ck during a peak period T;
FIG. 8 is a welding voltage setting / detection sampling diagram for sampling m times from the start of p.

FIG. 11 is a welding voltage setting / detection integrated value comparison diagram showing the set welding voltage integrated value Vss and the detected welding voltage integrated value Vi obtained by sampling and integrating in FIG. 10;

FIG. 12 is a diagram illustrating a control method of a welding current output by the welding device of the present invention.

FIG. 13 is a block diagram showing a control circuit in which the peak-base current control circuit IC of the welding apparatus for implementing the arc length control method of the present invention is configured by hardware.

FIG. 14 is a time t1 of an elapsed time t during welding;
FIG. 5 is a diagram showing a welding voltage value, an average welding current value Ia, and a change La of the arc length corresponding to the arc length when the arc passes through a position having a step.

FIG. 15 is a diagram showing a change in appearance of a weld bead when welding is performed by the arc length control of the present invention and an arc passes through a step.

[Explanation of symbols]

1: Wire 2: Workpiece AC: Commercial power supply AD1: Detection welding voltage A / D conversion circuit AD2: Setting welding voltage A / D conversion circuit AND1: AND circuit CM1: Setting / detection current comparison circuit CM2: Setting / detection welding Voltage comparison circuit Ck ... Clock signal Cm1 ... Welding current control signal Cm2 ... Setting / detection welding voltage comparison signal DA1 ... Welding current D / A conversion circuit DF ... Pulse frequency / width control circuit Df ... Pulse frequency / width control signal DSC ... Integration Detection / setting welding voltage comparison circuit DSI ... Detection welding voltage integration storage circuit f ... Pulse frequency IBM ... Base current value storage circuit IBS ... Base current value setting circuit IC ... Peak / base current control circuit ICD ... Control current digital signal output circuit IPB … Peak / base current value control circuit IPM… Peak current value storage circuit IPS… Peak current value setting times Ia: average welding current / average welding current value Ib: base current / base current value Ibs: base current value setting signal Ica: control current analog signal Icd: control current digital signal Id: welding current detection signal Ip: peak current / peak current Value Ips: Peak current value setting signal Isd: Welding current digital control signal L1: Arc length before step change L2: Arc length after step change La: Average arc length m: Number of samples PS: Pulse welding power supply SVI: Set welding voltage Integration storage circuit SW1 ... Peak / base current value switching circuit Sw1 ... Peak / base current value switching signal T, T1, T2 ... Pulse period TB ... Base period calculation circuit TBN ... Base period completion determination circuit TP ... Pulse width setting circuit TPB ... Peak period setting circuit TPC: Peak period counter Tb: Base period Tbk: Base period completed End signal Tm ... Sampling interval Tbn ... Base period Tp ... Peak period / pulse width setting signal Tpc ... Peak period count value / Peak period count signal Tpk ... Peak period completion signal Ts ... Electrification command signal VD ... Welding voltage instantaneous value detection circuit VDA ... Detection welding voltage smoothing circuit VF ... Voltage / frequency conversion circuit VS ... Welding voltage setting circuit Va ... Average welding voltage / average welding voltage value Va1 ... Average welding voltage value before step change Va2 ... Average welding voltage value after step change Vd ... Welding voltage instantaneous value detection signal Vda ... Detection welding voltage smoothing signal Vdd ... Detection welding voltage digital signal / welding voltage detection value Vf ... Frequency control signal Vi ... Integration detection voltage digital signal / detection welding voltage integration value Vs ... Welding voltage setting signal Vsd: Setting welding voltage digital signal / welding voltage setting value Vss: Integration setting welding voltage digital signal / setting Contact integrated voltage value WM ... wire feed motor WS ... wire feed rate setting circuit Ws ... wire feeding rate setting signal

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tsuneo Takeda 2-1-1-11 Tagawa, Yodogawa-ku, Osaka Inside Daihen Corporation

Claims (7)

[Claims] 1. An arc length control method for pulse arc welding in which a peak current is switched from a peak current to a base current after a preset peak period, and the peak current and the base current are repeatedly applied to the consumable electrode to perform welding. Value V
d is detected at a preset sampling interval shorter than the base period, and from the start of the peak period, the welding voltage set value and the welding voltage detection value are integrated and compared at the sampling interval, and the detected welding voltage integrated value is calculated. A method of controlling the arc length of pulsed arc welding, in which the base current is switched from the base current to the peak current at the time when the value becomes smaller than the set welding voltage integrated value, thereby restoring the arc length when the arc length fluctuates. 2. An arc length control method of pulse arc welding in which a peak current is switched from a peak current to a base current after a preset peak period, and the peak current and the base current are repeatedly applied to the consumable electrode to perform welding. A peak period completion determination step for determining whether the period has reached a set peak period; and a peak current output that outputs a peak current of a set current value and repeats until the peak period is reached when the peak period has not been reached. Step and a base current output step that outputs the base current of the set current value when the set peak period has been reached, and outputs a base current of the set current value when the completion of the base period has not been determined Until the completion of the base period is determined, and when the completion of the base period is determined, the next peak period is started. The repetitive start step to start, and the instantaneous value of the welding voltage is detected at a preset sampling interval shorter than the base period, and the welding voltage set value and the welding voltage detection value are integrated at the sampling interval from the start of the peak period. And determining whether the base period has been completed when the detected welding voltage integrated value becomes smaller than the set welding voltage integrated value. A pulse arc welding method that repeats a set peak period for energizing and a base period for energizing a base current after the peak period has elapsed until the base period completion signal is output. 3. An arc length control method of pulse arc welding in which a peak current is switched from a peak current to a base current after a preset peak period, and the peak current and the base current are repeatedly applied to the consumable electrode for welding. During the welding in which the energization command signal is continued, a peak period completion determining step for determining whether the peak period has been reached, and a peak current output step for outputting a peak current value when the set peak period has not been reached. And adding the sampled welding voltage detection value to the detected welding voltage integrated value integrated up to the previous time and storing the added detected welding voltage integrated value. A welding voltage that adds the value to the set welding voltage integrated value integrated up to one time before and stores the added set welding voltage integrated value. The set value integration step is compared with the detected welding voltage integrated value and the set welding voltage integrated value. If the detected welding voltage integrated value exceeds the set welding voltage integrated value, the process returns to the peak period completion determining step. When the set peak period has been reached, the base period is started, the base current value is applied, and the detected welding voltage integrated value is greater than the set welding voltage integrated value. At the point in time when the period becomes small, the base period is terminated, and the next peak period is started. The set period includes a set peak period in which the peak current is supplied until the conduction command signal ends, and a peak period. And a base period in which a base current is applied until the base period completion signal is output after the elapse of the pulse arc welding method. 4. An arc length control method of pulse arc welding in which a peak current is switched from a peak current to a base current after a preset peak period, and the peak current and the base current are repeatedly applied to the consumable electrode to perform welding. During welding, where the energization command signal continues, the number of clock signals input during the peak period is counted to determine whether the peak period count value has reached the set number of times in the set peak period. When the peak period count value has not reached the set number of peak periods, the control current digital signal having the value of the peak current value as the value of the control current digital signal and the value of the peak current value, A peak current output step to be output to the control current D / A conversion circuit; and a welding voltage detection value detected for each clock signal. Voltage A
And adding the sampled welding voltage detection value read from the / D conversion circuit to the detected welding voltage integrated value integrated up to one time before, and storing the added detected welding voltage integrated value. Set the welding voltage set value for each clock signal.
A welding voltage set value reading step of adding the sampled welding voltage set value read from the / D conversion circuit and sampled to the set welding voltage integrated value integrated up to one time before, and storing the added set welding voltage integrated value; , For each clock signal, compare the detected welding voltage integrated value with the set welding voltage integrated value, and if the detected welding voltage integrated value exceeds the set welding voltage integrated value, return to the peak period completion determination step and execute Repeat the integration detection and set welding voltage comparison step, and when the set peak period is reached, start the base period, apply the base current value, and make the detected welding voltage integrated value smaller than the set welding voltage integrated value. The base period is terminated at the point in time, and a base period execution step is started to start the next peak period. A peak period that the pulse arc welding method of repeating a base period for energizing the base current to the base period completion signal after lapse of the peak period is outputted. 5. A pulse arc welding apparatus for switching from a peak current to a base current after a preset peak period, and repeatedly applying the peak current and the base current to the consumable electrode to perform welding. A voltage digital signal is input, and at each sampling interval, the welding voltage set value and the welding voltage detection value are integrated and compared from the start of the peak period, and the detected welding voltage integrated value is greater than the set welding voltage integrated value. A base period completion discriminating circuit that outputs a base period completion signal when it becomes small, and outputs a set peak current during a set peak period,
The base period is started by passing the set base current after the elapse of the peak period, and when the base period completion signal is output, the peak period setting circuit for terminating the base period is provided. A pulse arc welding apparatus that repeats a set peak period in which a peak current is supplied until the base period is completed and a base period in which the base current is supplied until the base period completion signal is output after the peak period. 6. A pulse arc welding apparatus for switching from a peak current to a base current after a preset peak period, and repeatedly applying the peak current and the base current to the consumable electrode to perform welding. A voltage digital signal is input, and at each sampling interval, the welding voltage set value and the welding voltage detection value are integrated and compared from the start of the peak period, and the detected welding voltage integrated value is higher than the set welding voltage integrated value. A base period completion discriminating circuit that outputs a base period completion signal when it becomes small, and outputs a set peak current during a set peak period,
The base period is started by passing the set base current after the elapse of the peak period, and when the base period completion signal is output, a peak period setting circuit for ending the base period and a pulse width setting signal are inputted. A peak / base current value control circuit that outputs a peak current value setting signal set during a set peak period and then outputs a base current value setting signal during a base period, and controls by inputting a control current digital signal A welding current digital / analog conversion circuit that outputs a current analog signal, a welding current detection signal and a control current analog signal are input, and the welding current control signal of the difference is output to a pulse welding power supply to control the welding current value. A set and detected current comparison circuit, and a set peak period during which the peak current flows until the energization command signal ends, and the lapse of the peak period A pulse arc welding apparatus that repeats a base period in which a base current is supplied thereafter until the base period completion signal is output. 7. A base period completion determining circuit according to claim 5 or 6, wherein a set welding voltage digital signal is inputted,
At each sampling interval, from the start of the peak period, the set voltage detection value is integrated, and a set welding voltage integration storage circuit that stores the integrated set welding voltage integrated value, and a detected welding voltage digital signal is input to perform sampling. At each interval, from the start of the peak period, the welding voltage detection value is integrated, and the detected welding voltage integration storage circuit that stores the integrated detected welding voltage integrated value; and the detected welding voltage integrated value and the set welding voltage integrated value. And compare
A pulse arc welding apparatus which is an integrated detection / set welding voltage comparison circuit which outputs a base period completion signal when the detected welding voltage integrated value becomes smaller than the set welding voltage integrated value.