JP6100607B2 - Output control method of pulse arc welding - Google Patents

Description

  The present invention relates to an output control method for pulse arc welding in which a welding wire is fed and welding is performed by repeatedly applying a peak current during a peak period and a base current during a base period as one pulse period, and in particular, based on a short-circuit occurrence time. The present invention relates to optimization of the pulse waveform.

  A consumable electrode type pulse that feeds a welding wire at a constant speed, energizes a welding current with a pulse waveform with the peak current during the peak period and the base current during the base period as one pulse period, and generates an arc for welding. Arc welding methods are widely used. This pulse arc welding method can perform high-quality welding with less spatter generation on various metal materials such as steel and aluminum with high efficiency.

  FIG. 5 is a general current / voltage waveform diagram in consumable electrode type pulse arc welding. FIG. 4A shows the waveform of the welding current Iw for energizing the arc, and FIG. 4B shows the waveform of the welding voltage Vw applied between the welding wire and the base material. Hereinafter, a description will be given with reference to FIG.

  During the peak period Tp from time t1 to t2, as shown in FIG. 6A, the peak current Ip exceeding the critical value is energized in order to rise and form a droplet and transfer the droplet. As shown in (B), a peak voltage Vp rising with an inclination and proportional to the arc length is applied. During the base period Tb from time t2 to time t3, as shown in FIG. 6A, the base current Ib less than the critical value is energized in order to fall with a slope and not form droplets. As shown in B), the base voltage Vb falls with a slope and is proportional to the arc length. Welding is performed by repeating the times t1 to t3 as one pulse period Tf.

  When the welding wire is a steel wire having a diameter of 1.2 mm, the peak current Ip = 450 to 500 A, the peak period including the rise Tp = 1.5 to 2.0 ms, the pulse period Tf = 4.0 to 10.0 ms, the base The current Ib is set to 30 to 70 A, the rising period and the falling period are set to about 0.5 to 1.0 ms.

  During the peak period Tp, the tip of the welding wire is melted to grow a droplet, and a constriction due to a pinch force is gradually formed on the top of the droplet. Then, at time t2, the base period Tb is entered, and at time t21 immediately after the welding current Iw falls and converges to the base current Ib, the droplets move to the molten pool. At the time of this transition, since the droplets are elongated and come into contact with the molten pool, a short circuit occurs for a short time (mostly less than 0.2 ms). Therefore, as shown in FIG. 5B, at time t21, the welding voltage Vw becomes substantially 0 V, and a short circuit has occurred. There is no change in the welding current Iw shown in FIG. 5A, and the base current Ib remains unchanged. However, when the short circuit period becomes a reference time (for example, 1 ms) or longer, control is performed to gradually increase the welding current Iw in order to release the short circuit at an early stage. From the above, the timing of droplet transfer can be detected by detecting the occurrence of a short circuit.

  In consumable electrode type arc welding including pulse arc welding, maintaining the arc length during welding at an appropriate value is important for obtaining good welding quality. This arc length control is performed as follows. The average value Vav of the welding voltage shown in FIG. 5B is substantially proportional to the arc length. For this purpose, the welding voltage average value Vav is detected, and the above pulse is set so that the welding voltage average value Vav becomes equal to the welding voltage setting value Vr (not shown) set to a value corresponding to the appropriate arc length. The period Tf (frequency modulation control), the peak period Tp (pulse width modulation control) or the peak current Ip (peak current modulation control) is changed by feedback control. The base current Ib is set to a predetermined value.

  In the frequency modulation control, the peak period Tp and the peak current Ip are pulse parameters and are set to predetermined values. The pulse period Tf (base period Tb) is feedback controlled.

  In the pulse width modulation control, the pulse period Tf and the peak current Ip are pulse parameters and are set to predetermined values. Then, the peak period (pulse width) Tp is feedback controlled.

  In the peak current modulation control, the peak period Tp and the pulse period Tf are pulse parameters and are set to predetermined values. Then, the peak current Ip is feedback controlled.

  The welding voltage average value Vav is detected by detecting the welding voltage Vw and passing it through a low-pass filter (cutoff frequency of about 1 to 10 Hz).

  In each modulation control, the pulse parameter is set to an appropriate value so as to be in a so-called 1 pulse period 1 droplet transfer state in which one droplet transfers during one pulse period. In particular, when the droplet transfer timing is performed within a predetermined period after the falling period from the end of the peak period Tp, the pulse parameter is set to an optimum value.

  The optimum value of the pulse parameter is different depending on the brand of the welding wire even if the welding wire has the same JIS standard. Further, the optimum value varies depending on the distance between the power feed tip and the base material (torch height), the feeding speed, the welding speed, and the like. For this reason, control for automatically adjusting the pulse parameter to an optimum value has been proposed (see Patent Document 1).

  In the invention of Patent Document 1, a short-circuit between the welding wire and the base material is detected, and it is determined whether the short-circuit occurrence time is an early region, an appropriate region, or a late region with respect to the pulse period. Is automatically adjusted. For example, when the peak period Tp is selected as the pulse parameter to be automatically adjusted, when the short-circuit occurrence timing in the nth pulse cycle is in the early region, the peak period Tp is shortened by 0.1 ms, and the (n + 1) th When the short-circuit occurrence time in the second pulse period is in an appropriate region, the peak engine Tp maintains the value as it is. In addition, when the short-circuit occurrence time in the m-th pulse cycle is in the late region, the peak engine Tp is lengthened by 0.1 ms. n and m are positive integers. In this way, automatic adjustment of pulse parameters is performed.

Japanese Patent No. 2973714

  In the above-described prior art, the droplet transfer timing is detected by detecting the short-circuit occurrence timing for each pulse cycle, and it is determined whether this short-circuit occurrence timing is an early region, an appropriate region, or a late region with respect to the pulse cycle. The pulse parameters are automatically adjusted based on this determination.

  However, even if the welding conditions remain the same and the pulse parameter is the optimum value, the droplet transfer timing has some variation. For this reason, the occurrence of the short circuit occurs in an early region or a later region with a certain probability. In the prior art, although the pulse parameter is set to an optimum value, there are cases where the pulse parameter constantly changes every pulse period due to this variation. As a result, the droplet transfer state may become unstable.

  Therefore, an object of the present invention is to provide a pulse arc welding output control method capable of stably performing automatic adjustment of pulse parameters even when the droplet transfer timing varies.

In order to solve the above-described problems, the invention of claim 1 is a pulse arc welding in which a welding wire is fed and welding is performed by repeatedly applying a peak current during a peak period and a base current during a base period as one pulse period. In the output control method of
The occurrence time of the short circuit between the welding wire and the base material is detected for each pulse period, and an index representing the distribution of the short circuit occurrence time per unit time is calculated. Based on this index, the pulse in the waveform of the welding current is calculated. Changing the parameters,
An output control method of pulse arc welding characterized by the above.

The invention of claim 2 divides the pulse period into an early region, an appropriate region, and a late region in advance, and the short-circuit occurrence time detected per unit time is determined as the early region, the appropriate region, or the late region. The index is a region where the value of the count is the largest,
The output control method for pulse arc welding according to claim 1, wherein:

According to a third aspect of the present invention, the short-circuit occurrence time is detected as time with the end time of the peak period as a reference time and a negative value before and as a positive value, and the index is the time per unit time. It is an average value of the time indicating the short circuit occurrence time,
The output control method for pulse arc welding according to claim 1, wherein:

  In the prior art, the pulse parameters are automatically adjusted for each pulse period based on the short circuit occurrence timing. On the other hand, according to the present invention, the pulse parameter is automatically adjusted based on a value obtained by statistically processing the short-circuit occurrence timing for each unit time including a plurality of pulse periods. For this reason, in the present invention, even if the droplet transfer timing varies, automatic adjustment of pulse parameters can be performed stably.

It is an electric current / voltage waveform diagram for demonstrating the output control method of the pulse arc welding which concerns on Embodiment 1 of this invention. It is a block diagram of the welding power supply for implementing the output control method of the pulse arc welding which concerns on Embodiment 1 of this invention. It is an electric current / voltage waveform diagram for demonstrating the output control method of the pulse arc welding which concerns on Embodiment 2 of this invention. It is a block diagram of the welding power supply for implementing the output control method of the pulse arc welding which concerns on Embodiment 2 of this invention. In a prior art, it is a general electric current and voltage waveform figure in consumable electrode type pulse arc welding.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
In the first embodiment, a case will be described in which the arc length control method is frequency modulation control and the pulse parameter to be automatically adjusted is the peak period Tp. Therefore, the peak current Ip and the base current Ib, which are other pulse parameters, are set to predetermined values, and the pulse period Tf is feedback controlled.

  FIG. 1 is a current / voltage waveform diagram for explaining an output control method of pulse arc welding according to Embodiment 1 of the present invention. FIG. 4A shows the waveform of the welding current Iw, and FIG. 4B shows the waveform of the welding voltage Vw. Since this figure has the same waveform as FIG. 5 described above, the same description will not be repeated. Hereinafter, the automatic adjustment control of the peak period Tp will be described with reference to FIG.

Step 1: In the figure, the time period from the time t1 at which the pulse period Tf starts to the time t2 at which the peak period Tp ends is defined as the early period, and the period from the time t2 to the time t22 when the predetermined period Tt elapses is defined as the appropriate period. The period from t22 to time t3 when the next pulse period Tf starts is defined in advance as a late region. The predetermined period Tt is set so that the peak current Ip falls and converges to the base current Ib. This predetermined period Tt is set by experiment in consideration of the transient response and the steady stability of the automatic adjustment control of the pulse parameter. As a numerical example, an early region (peak period Tp) at time t1 to t2 = 2.0 ms, an appropriate region (predetermined period Tt) at time t2 to t22 = 1.5 ms, and a later region at time t22 to t3 = 0. .5 to 6.5 ms.

Step 2: Determine the occurrence of a short circuit. The occurrence of a short circuit is determined by the welding voltage Vw being lowered to about 0V as shown in FIG.

Step 3: The occurrence time of the determined short circuit is detected. And every predetermined unit time, it classifies and counts into the early area | region, the appropriate period area | region, or the latter period area | region according to the generation | occurrence | production time of the determined short circuit. The unit time is set in a range of about 0.1 to 5.0 seconds. Since the pulse frequency is in the range of about 100 to 250 Hz, 10 to 25 short circuits occur in 0.1 seconds and 500 to 1250 short circuits occur in 5.0 seconds. These short-circuits are classified into the above three regions and counted according to the generation time.

Step 4: For each unit time, an area having the largest count value is determined. When the area is an early area, an index Sd = 1 is output, and when the area is an appropriate period, an index Sd = 2 is output. In the case of the late region, the index Sd = 3 is output. The index Sd represents the distribution of short circuit occurrence times. After the index Sd is output, the count of each area is reset to zero.

Step 5: For each unit time, the peak period Tp is increased or decreased by a predetermined correction amount Δd according to the value of the index Sd. The correction amount Δd is a positive real number and is set to about 0.05 to 0.3 ms. Since the correction amount Δd corresponds to the gain of the automatic adjustment control of the pulse parameter, the correction amount Δd is set to an appropriate value by experiment in consideration of the transient response and the steady stability. The increase / decrease is performed as follows. Tp (m) is a set value of the peak period at the present time, and Tp (m + 1) is a set value of the peak period after increase / decrease. m is an integer of 1 or more.
When Sd = 1, Tp (m + 1) = Tp (m) −Δd
When Sd = 2, Tp (m + 1) = Tp (m)
When Sd = 3, Tp (m + 1) = Tp (m) + Δd

  When the index Sd = 1, the occurrence time of the short circuit generated per unit time is most distributed in the early region, and in this case, the current set value of the peak period Tp is longer than the optimum value. It is. For this reason, the current set value of the peak period Tp is shortened by the correction amount Δd.

  When the index Sd = 2, the occurrence time of the short circuit generated per unit time is distributed most in the appropriate period, and in this case, the current set value of the peak period Tp is the optimum value. It is. For this reason, the current set value of the peak period Tp is maintained as it is.

  When the index Sd = 3, the occurrence time of the short circuit generated per unit time is most distributed in the late region, and in this case, the current set value of the peak period Tp is shorter than the optimum value. It is. For this reason, the current set value of the peak period Tp is lengthened by the correction amount Δd.

  The automatic adjustment control of the peak period Tp is performed by steps 1 to 5 described above. In the above, automatic adjustment control of the peak current Ip may be performed simultaneously. In this case, the peak current Ip may be automatically adjusted according to the value of the index Sd. That is, the current set value of the peak current Ip is decreased by a predetermined correction amount when the index Sd = 1, maintained as it is when Sd = 2, and is increased by the correction amount when Sd = 3. .

  In the case of pulse width modulation control, the pulse period Tf and / or peak current Ip may be automatically adjusted according to the value of the index Sd. Similarly, in the case of peak current modulation control, the peak period Tp and / or the pulse period Tf may be automatically adjusted according to the value of the index Sd.

  FIG. 2 is a block diagram of a welding power source for carrying out the output control method of pulse arc welding according to the first embodiment of the present invention described above with reference to FIG. Hereinafter, each block will be described with reference to FIG.

  The power supply main circuit PM receives a commercial power supply (not shown) such as three-phase 200V as input, performs output control by inverter control according to a drive signal Dv described later, and outputs a welding current Iw and a welding voltage Vw. Although not shown, the power supply main circuit PM includes a primary rectifier that rectifies commercial power, a capacitor that smoothes the rectified direct current, an inverter circuit that converts the smoothed direct current into high-frequency alternating current according to the drive signal Dv, A high-frequency transformer that steps down the high-frequency alternating current to a voltage value suitable for arc welding, a secondary rectifier that rectifies the stepped-down high-frequency alternating current, and a reactor that smoothes the rectified direct current are provided.

  The welding wire 1 is wound around a wire reel 1a. The welding wire 1 is fed through the welding torch 4 by the rotation of the feed roll 5 coupled to the wire feed motor WM, and the arc 3 is generated between the base metal 2 and welding is performed. A welding current Iw is passed through the arc 3, and a welding voltage Vw is applied between the welding wire 1 and the base material 2.

  The welding voltage detection circuit VD detects the welding voltage Vw and outputs a welding voltage detection signal Vd. The welding voltage average value calculation circuit VAV receives the welding voltage detection signal Vd as an input, averages it by passing it through a low-pass filter, and outputs a welding voltage average value signal Vav. The welding voltage setting circuit VR outputs a predetermined welding voltage setting signal Vr. The voltage error amplification circuit EV amplifies an error between the welding voltage setting signal Vr and the welding voltage average value signal Vav, and outputs a voltage error amplification signal Ev.

  The voltage / frequency conversion circuit VF receives the voltage error amplification signal Ev, and outputs a pulse period signal Tf having a frequency corresponding to the value of the voltage error amplification signal Ev. The pulse cycle signal Tf is a signal that becomes a high level for a short time every pulse cycle.

  The short circuit determination circuit SA receives the welding voltage detection signal Vd as described above, determines the short circuit state based on the value, and outputs a short circuit determination signal Sa that becomes a high level. This circuit performs the operation of step 2 described above.

The index generation circuit SD receives the pulse period signal Tf, the peak period correction setting signal Tps, which will be described later, and the short circuit determination signal Sa as described above, performs the following processing, and outputs the index signal Sd.
1) The occurrence time of the determined short circuit is detected. The detection of the short circuit occurrence time is performed as follows. The time when the short circuit determination signal Sa changes to the high level is a period determined by the peak period correction setting signal Tps from the time when the pulse period signal Tf changes to the high level (time t1 in FIG. 1) (FIG. It is determined that a short circuit has occurred in the early region when it is 1 time t1 to t2), and then a short circuit has occurred in the appropriate region during a predetermined period Tt (time t2 to t22 in FIG. 1). If it is during the subsequent period (time t22 to t3 in FIG. 1), it is determined that a short circuit has occurred in the late region. (Operation 2 in Steps 1 and 3 described above) For each predetermined unit time, the determined short circuit is classified into an early region, an appropriate region, or a late region according to the occurrence time and counted. (Operation of Step 3 described above)
3) For each unit time, an area having the largest count value is determined. When the area is an early area, an index signal Sd = 1 is output, and when the area is an appropriate period, an index signal Sd = 2. And the index signal Sd = 3 is output in the latter period. The index signal Sd represents the distribution of short circuit occurrence times. After the index signal Sd is output, the count of each area is reset to zero. (Operation of Step 4 described above)

  The peak period setting circuit TPR outputs a predetermined peak period setting signal Tpr. The peak period correction setting circuit TPS receives the peak period setting signal Tpr and the above-described index signal Sd, and uses the value of the peak period setting signal Tpr as an initial value when the index signal Sd = 1 for each unit time. Subtracts a predetermined correction amount ΔD from the current set value, adds 0 when Sd = 2, adds Δd when Sd = 3, and outputs a peak period correction setting signal Tps. That is, Tps = Tpr + Σ (correction amount per unit time). This circuit performs the operation of step 5 described above.

  The timer circuit TM receives the peak period correction setting signal Tps and the pulse period signal Tf, and receives a high level only for a period determined by the peak period correction setting signal Tps every time the pulse period signal Tf changes to a high level. The signal Tm is output. Accordingly, when the timer signal Tm is at a high level, the peak period is set, and when the timer signal Tm is at a low level, a base period is set.

  The peak current setting circuit IPR outputs a predetermined peak current setting signal Ipr. The base current setting circuit IBR outputs a predetermined base current setting signal Ibr. The values of the peak period setting signal Tpr, the peak current setting signal Ipr, and the base current setting signal Ibr are as follows: welding wire material, diameter, brand, feed tip / base metal distance, feed speed, welding Assuming welding conditions that are standard with respect to welding conditions such as speed, an appropriate value is obtained and set by experiment under these standard welding conditions.

  The switching circuit SW receives the timer signal Tm, the peak current setting signal Ipr, and the base current setting signal Ibr, and when the timer signal Tm is at a high level, the switching circuit SW uses the peak current setting signal Ipr as the current control setting signal Icr. When the low level, the base current setting signal Ibr is output as the current control setting signal Icr.

  The welding current detection circuit ID detects the welding current Iw and outputs a welding current detection signal Id. The current error amplification circuit EI amplifies an error between the current control setting signal Icr and the welding current detection signal Id, and outputs a current error amplification signal Ei. The drive circuit DV receives the current error amplification signal Ei as input, performs PWM control, and outputs a drive signal Dv for driving the inverter circuit of the power supply main circuit PM.

  The welding current average value setting circuit IR outputs a predetermined welding current average value setting signal Ir. The feeding speed setting circuit FR receives the welding current average value setting signal Ir as an input, and corresponds to the value of the welding current average value setting signal Ir by the relational expression between the welding current average value and the feeding speed incorporated in advance. A feed speed setting signal Fr is calculated and output. The feed control circuit FC receives this feed speed setting signal Fr and outputs a feed control signal Fc for feeding the welding wire 1 at a feed speed determined by this value to the wire feed motor WM. To do.

  In the first embodiment described above, the pulse period is divided into an early region, an appropriate region, and a late region in advance, and the short-circuit occurrence timing detected per unit time is classified into the early region, the appropriate region, or the late region and counted. Then, the pulse parameter in the welding current waveform is changed and automatically adjusted based on the index corresponding to the region having the largest count value. In the prior art, the pulse parameters are automatically adjusted for each pulse period based on the short circuit occurrence timing. On the other hand, according to the present embodiment, the pulse parameter is automatically adjusted based on the cumulative value obtained by statistically processing the short-circuit occurrence timing for each unit time including a plurality of pulse periods. For this reason, in this embodiment, even if the droplet transfer timing varies, automatic adjustment of pulse parameters can be performed stably.

“Embodiment 2”
FIG. 3 is a current / voltage waveform diagram for explaining an output control method of pulse arc welding according to Embodiment 2 of the present invention. FIG. 4A shows the waveform of the welding current Iw, and FIG. 4B shows the waveform of the welding voltage Vw. Since this figure has the same waveform as FIG. 1 described above, the same description will not be repeated. Hereinafter, the automatic adjustment control of the peak period Tp will be described with reference to FIG.

Step 10: Determine the occurrence of a short circuit. The occurrence of a short circuit is determined by the welding voltage Vw being lowered to about 0V as shown in FIG. (Same operation as step 1 in FIG. 1)

Step 20: Determine the occurrence time of the short circuit as a time Td (time from t2 to t21) with the end time of the peak period (time t2) as a reference time and a negative value before that as a reference time. To detect. Then, for each predetermined unit time, an average value of the detected times Td is calculated and output as an index Sd. The index Sd represents the distribution of short circuit occurrence times.

Step 30: For each unit time, the peak period Tp is increased or decreased by a predetermined correction amount Δd according to the value of the index Sd. This correction amount Δd is the same as in FIG. The increase / decrease is performed as follows. Tp (m) is a set value of the peak period at the present time, and Tp (m + 1) is a set value of the peak period after increase / decrease. m is an integer of 1 or more. Tt is a predetermined period as in FIG.
When Sd <0, Tp (m + 1) = Tp (m) −Δd
When 0 ≦ Sd <Tt, Tp (m + 1) = Tp (n)
When Tt ≦ Sd, Tp (m + 1) = Tp (m) + Δd

  When the index Sd <0, the average value of the occurrence time of the short circuit generated per unit time exists in the early region defined in FIG. 1, and in this case, the current set value of the peak period Tp is This is when it is longer than the optimum value. For this reason, the current set value of the peak period Tp is shortened by the correction amount Δd.

  When the index Sd is 0 ≦ Sd <Tt, the average value of the occurrence time of the short circuit occurring per unit time is present in the appropriate period region defined in FIG. 1, and in this case, the peak period Tp This is when the current set value is the optimum value. For this reason, the current set value of the peak period Tp is maintained as it is.

  When the index Sd ≧ Tt, the average value of the occurrence time of the short circuit occurring per unit time is present in the latter period defined in FIG. 1, and in this case, the current set value of the peak period Tp is This is when it is shorter than the optimum value. For this reason, the current set value of the peak period Tp is lengthened by the correction amount Δd.

  The automatic adjustment control of the peak period Tp is performed by steps 10 to 30 described above. In the above, automatic adjustment control of the peak current Ip may be performed simultaneously. In this case, the peak current Ip may be automatically adjusted according to the value of the index Sd. In the case of pulse width modulation control, the pulse period Tf and / or peak current Ip may be automatically adjusted according to the value of the index Sd. Similarly, in the case of peak current modulation control, the peak period Tp and / or the pulse period Tf may be automatically adjusted according to the value of the index Sd.

  FIG. 4 is a block diagram of a welding power source for carrying out the pulse arc welding output control method according to the second embodiment of the present invention described above with reference to FIG. This figure corresponds to FIG. 2 described above, and the same reference numerals are given to the same blocks, and the description thereof will not be repeated. This figure is obtained by replacing the index generation circuit SD of FIG. 2 with a second index generation circuit SD2, and replacing the peak period correction setting circuit TPS of FIG. 2 with a second peak period correction setting circuit TPS2. Hereinafter, these blocks will be described with reference to FIG.

The second index generation circuit SD2 receives the pulse period signal Tf, the peak period correction setting signal Tps, and the short circuit determination signal Sa, performs the following processing, and outputs the index signal Sd.
1) The occurrence time of the determined short circuit is detected. The detection of the short circuit occurrence time is performed as follows. A time Ta from the time point when the pulse period signal Tf changes to the high level (time t1 in FIG. 3) to the time point when the short circuit determination signal Sa changes to the high level (time t21 in FIG. 3) is measured. Then, a time Td = Ta−Tps indicating a short circuit occurrence time is calculated. (Operation 2 of Step 20 described above) For each predetermined unit time, an average value of each time Td of the detected short-circuit occurrence timing is calculated and output as an index signal Sd. (Operation of Step 20 described above)

  The second peak period correction setting circuit TPS2 receives the peak period setting signal Tpr and the index signal Sd as input, sets the value of the peak period setting signal Tpr as an initial value, and sets the index signal Sd <0 for each unit time. At this time, a predetermined correction amount ΔD is subtracted from the current set value. When 0 ≦ Sd <Tt, 0 is added. When Tt ≦ Sd, Δd is added to output the peak period correction setting signal Tps. To do. Tt is a predetermined period. That is, Tps = Tpr + Σ (correction amount per unit time). This circuit performs the operation of step 30 described above.

  In the second embodiment described above, the short-circuit occurrence time is detected as time with the end time of the peak period as a reference time and before that as a negative value, and after that as a positive value, and the average value of these times per unit time Based on the index, the pulse parameter in the welding current waveform is changed and automatically adjusted. In the prior art, the pulse parameters are automatically adjusted for each pulse period based on the short circuit occurrence timing. On the other hand, according to the present embodiment, the pulse parameter is automatically adjusted based on the average value of the time when the short-circuit occurrence time is statistically processed for each unit time including a plurality of pulse periods. For this reason, in this embodiment, even if the droplet transfer timing varies, automatic adjustment of pulse parameters can be performed stably.

DESCRIPTION OF SYMBOLS 1 Welding wire 1a Wire reel 2 Base material 3 Arc 4 Welding torch 5 Feed roll Dv Drive signal EI Current error amplification circuit Ei Current error amplification signal EV Voltage error amplification circuit EV Voltage error amplification signal FC Feed control circuit Fc Feed control Signal FR Feeding speed setting circuit Fr Feeding speed setting signal Ib Base current IBR Base current setting circuit Ibr Base current setting signal Icr Current control setting signal ID Welding current detection circuit Id Welding current detection signal Ip Peak current IPR Peak current setting circuit Ipr Peak current setting signal IR Welding current average value setting circuit Ir Welding current average value setting signal Iw Welding current PM Power supply main circuit SA Short circuit determining circuit Sa Short circuit determining signal SD Index generating circuit Sd Index (signal)
SD2 Second index generation circuit SW switching circuit Ta Time from start time of pulse period Tb Base period Td Time from end time of peak period Tf Pulse period (signal)
TM timer circuit Tm timer signal Tp peak period TPR peak period setting circuit Tpr peak period setting signal TPS peak period correction setting circuit Tps peak period correction setting signal TPS2 second peak period correction setting circuit Tt predetermined period VAV welding voltage average value calculation circuit Vav Average welding voltage (signal)
Vb Base voltage VD Welding voltage detection circuit Vd Welding voltage detection signal VF Voltage / frequency conversion circuit Vp Peak voltage VR Welding voltage setting circuit Vr Welding voltage setting signal Vw Welding voltage WM Wire feed motor Δd Correction amount

Claims (3)

In an output control method of pulse arc welding in which a welding wire is fed and welding is performed by repeatedly energizing a peak current during a peak period and a base current during a base period as one pulse period
The occurrence time of the short circuit between the welding wire and the base material is detected for each pulse period, and an index representing the distribution of the short circuit occurrence time per unit time is calculated. Based on this index, the pulse in the waveform of the welding current is calculated. Changing the parameters,
An output control method of pulse arc welding characterized by the above. The pulse period is divided into an early region, a proper region and a late region in advance, and the short-circuit occurrence timing detected per unit time is classified into the early region, the proper region or the late region, and counted. The indicator is a region where the count value is the largest,
The output control method of pulse arc welding according to claim 1. The short-circuit occurrence time is detected as time with the end time of the peak period as a reference time and a negative value before and a positive value after that, and the index indicates the time indicating the short-circuit occurrence time per unit time. Is the average value of
The output control method of pulse arc welding according to claim 1.

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