Ac pulse arc welding control method

Abstract

The AC pulse arc welding control method includes energization control in an electrode positive polarity period and an electrode negative polarity period. In the electrode positive polarity period, a transition current rising from the value of a base current to the value of a peak current is energized, the peak current is energized, a transition current descending from the value of the peak current to the value of the base current is energized, and the base current is energized. In the electrode negative polarity period, an electrode negative polarity current is energized. Feeding of the welding wire includes repetition of feeding by a forward feeding peak value and feeding by a reverse feeding peak value. During the base period and the electrode negative polarity period, the feeding speed of the welding wire is a reverse feeding peak value.

Description

AC pulse arc welding control method

[0001] The present disclosure relates to a method for controlling AC pulse arc welding in which welding wire is fed and welding is performed.

[0002] Pulse arc welding, which involves feeding a welding wire for welding, is widely used for welding steel and the like. To increase the welding speed for the purpose of improving welding efficiency, it is necessary to increase the melting rate of the welding wire. In AC pulse arc welding, by providing a negative electrode polarity period, the melting rate of the welding wire can be increased by approximately 1.5 times compared to DC pulse arc welding. In AC pulse arc welding, the welding wire is fed, and during the positive electrode polarity period, a peak rise current is passed that rises from a base current value to a peak current value during the peak rise period, a peak current is passed during the peak period, a peak fall current is passed that falls from the peak current value to a base current value during the peak fall period, a base current is passed during the base period, and a negative electrode polarity current is passed during the negative electrode polarity period. These current passes constitute one pulse period, and welding is performed by repeating these current passes. In pulse arc welding, by achieving one droplet transfer per pulse period, spatter generation is reduced and a beautiful bead appearance can be achieved.

[0003] In the invention of Patent Document 1, during a predetermined period from a first point in time during the peak period to a second point in time during the base period, the welding wire feed speed is set to be slower than the feed speed at the rising point of the peak current, or the welding wire is fed in a reverse direction, i.e., in a direction away from the workpiece to be welded.

[0004] Patent No. 6123069

[0005] In AC pulsed arc welding, the size of the droplets formed at the tip of the welding wire is larger than in DC pulsed arc welding. For this reason, in conventional AC pulsed arc welding, there is a problem that the state of one droplet transfer per pulse cycle deviates, resulting in poor welding quality.

[0006] Therefore, an object of the present disclosure is to provide an AC pulse arc welding control method that can always maintain a one-droplet-per-pulse-cycle state and obtain good welding quality.

[0007] According to a first aspect of the present disclosure, there is provided an AC pulse arc welding control method comprising: feeding a welding wire; during an electrode positive polarity period, passing a peak rise current that rises from a base current value to a peak current value during a peak rise period, passing the peak current during the peak period, passing a peak fall current that falls from the peak current value to the base current value during a peak fall period, and passing the base current during the base period; and passing an electrode negative polarity current during an electrode negative polarity period; and repeating the passing of current during the electrode positive polarity period and the electrode negative polarity period as one pulse period, wherein the feeding of the welding wire includes repeatedly feeding the welding wire in a forward direction and a reverse direction, and the reverse feeding of the welding wire is performed at least during the base period and the electrode negative polarity period.

[0008] Preferably, the welding wire feed speed starts to change from a reverse feed peak value to a forward feed peak value at a start of the peak rise period, and starts to change from the forward feed peak value to the reverse feed peak value at a start of the peak fall period.

[0009] Preferably, the period of change from the forward transport peak value to the backward transport peak value is equal to or shorter than the peak fall period.

[0010] Preferably, the absolute value of the reverse transport peak value is set to a value greater during the electrode negative polarity period than during the base period.

[0011] Preferably, the arc length is controlled by modulating at least the peak current, and the electrode negative polarity current ratio is maintained at a set value by modulating the electrode negative polarity current.

[0012] According to the AC pulse arc welding control method of the present disclosure, a one-droplet-per-pulse-cycle state can be constantly maintained, thereby obtaining good welding quality.

[0013] 1 is a block diagram of a welding device for implementing an AC pulse arc welding control method according to an embodiment of the present disclosure, and FIG. 2 is a timing chart of signals in the welding device of FIG. 1 illustrating an AC pulse arc welding control method according to an embodiment of the present disclosure.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0015] 1 is a block diagram of a welding apparatus for carrying out an AC pulse arc welding control method according to an embodiment of the present disclosure. The welding apparatus is composed of a welding power source PS, a robot control device RC, a robot (not shown), etc., all of which are enclosed by a dashed line. Each block will be described below with reference to the diagram.

[0016] The welding power source PS is composed of the following blocks:

[0017] The power control circuit MC is connected to a three-phase 200V or other AC commercial power supply (not shown), and receives a drive signal Dv and a polarity switching signal Spn (described later) as inputs to perform output control such as inverter control in accordance with the drive signal Dv, switches between electrode positive polarity EP and electrode negative polarity EN in accordance with the polarity switching signal Spn, and outputs an AC welding voltage Vw and welding current Iw suitable for welding. Although not shown, the power control circuit MC includes a primary rectifier circuit that rectifies the AC commercial power supply, a capacitor that smoothes the rectified DC, a primary-side inverter circuit that converts the smoothed DC to high-frequency AC in accordance with the drive signal Dv, an inverter transformer that steps down the high-frequency AC to a voltage value suitable for welding, a secondary rectifier circuit that rectifies the stepped-down high-frequency AC, a reactor that smooths the rectified DC, and a secondary-side inverter circuit that switches the smoothed DC between electrode positive polarity EP and electrode negative polarity EN in accordance with the polarity switching signal Spn.

[0018] The feed motor WM is rotationally driven by a feed control signal Fc, which will be described later. The welding wire 1 is fed forward and backward through the welding torch 4 at a feed speed Fw by the rotation of a feed roll 5 coupled to the feed motor WM, and an arc 3 is generated between the welding wire 1 and the base material 2. The feed motor WM and the welding torch 4 are mounted on a robot. A welding voltage Vw is applied between a power feed tip (not shown) in the welding torch 4 and the base material 2, and a welding current Iw flows.

[0019] The welding voltage detection circuit VD detects the AC welding voltage Vw, converts it to an absolute value, and outputs a welding voltage detection signal Vd. The welding voltage averaging circuit VAV averages the welding voltage detection signal Vd (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 amplifier circuit EV amplifies the error between the welding voltage setting signal Vr(+) and the welding voltage average value signal Vav(-) and outputs a voltage error amplification signal Ev.

[0020] The current modulation circuit IC receives the voltage error amplified signal Ev, performs PI (proportional-integral) control or PID (proportional-integral-derivative) control, and outputs a peak current setting signal Ipr and a base current setting signal Ibr. This circuit performs current modulation control of the peak current setting signal Ipr and the base current setting signal Ibr so that the welding voltage average value signal Vav becomes equal to the welding voltage setting signal Vr. As a result, arc length control is performed so that the arc length is maintained at an appropriate value. It is also possible to perform current modulation control of only the peak current setting signal Ipr, and set the base current setting signal Ibr to a predetermined value.

[0021] The peak rise period setting circuit TUR outputs a predetermined peak rise period setting signal Tur. The peak period setting circuit TPR outputs a predetermined peak period setting signal Tpr. The peak fall period setting circuit TKR outputs a predetermined peak fall period setting signal Tkr. The base period setting circuit TBR outputs a predetermined base period setting signal Tbr.

[0022] The electrode negative polarity period setting circuit TNR outputs a predetermined electrode negative polarity period setting signal Tnr.

[0023] The welding current setting circuit IR receives the peak rise period setting signal Tur, the peak period setting signal Tpr, the peak fall setting signal Tkr, the base period setting signal Tbr, the electrode negative polarity period setting signal Tnr, the peak current setting signal Ipr, the base current setting signal Ibr, and an electrode negative polarity current setting signal Inr (described later) as inputs, performs the following processing, and outputs a welding current setting signal Ir and a timer signal Tm: 1) During the peak rise period Tu determined by the peak rise period setting signal Tur, it outputs a timer signal Tm=1, and outputs the peak rise current Iu that rises from the value of the base current setting signal Ibr to the value of the peak current setting signal Ipr as the welding current setting signal Ir; 2) Subsequently, during the peak period Tp determined by the peak period setting signal Tpr, it outputs a timer signal Tm=2, and outputs the peak current setting signal Ipr as the welding current setting signal Ir. 3) Subsequently, during the peak fall period Tk determined by the peak fall period setting signal Tkr, a timer signal Tm=3 is output, and the peak fall current Ik decreasing from the value of the peak current setting signal Ipr to the value of the base current setting signal Ibr is output as the welding current setting signal Ir. 4) Subsequently, during the base period Tb determined by the base period setting signal Tbr, a timer signal Tm=4 is output, and the base current setting signal Ibr is output as the welding current setting signal Ir. 5) Subsequently, during the electrode negative polarity period Ten determined by the electrode negative polarity period setting signal Tnr, a timer signal Tm=5 is output, and the electrode negative polarity current setting signal Inr is output as the welding current setting signal Ir, and just before the end of the electrode negative polarity period Ten, a current setting signal Ir decreasing to the value of the base current setting signal Ibr is output. 6) The above steps 1) to 5) are repeated.

[0024] The polarity switching circuit SPN receives the timer signal Tm as an input and outputs a polarity switching signal Spn that is at a high level when the timer signal Tm=1 to 4 (electrode positive polarity Tep) and at a low level when the timer signal Tm=5 (electrode negative polarity period Ten).

[0025] The positive transmission peak value setting circuit WSR outputs a positive transmission peak value setting signal Wsr of a predetermined positive value.

[0026] The backward transmission peak value setting circuit WRR outputs a backward transmission peak value setting signal Wrr having a predetermined negative value.

[0027] The electrode negative polarity period backward transmission peak value setting circuit WNR outputs an electrode negative polarity period backward transmission peak value setting signal Wnr having a predetermined negative value.

[0028] The welding current detection circuit ID detects the AC welding current Iw, converts it to an absolute value, and outputs a welding current detection signal Id. The current error amplifier circuit EI amplifies the error between the welding current setting signal Ir(+) 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 and an activation signal On from a robot control device RC (described later), and performs PWM modulation control based on the current error amplification signal Ei when the activation signal On is high (welding start) and outputs a drive signal Dv for driving the primary inverter circuit in the power control circuit MC. When the activation signal On is low (welding stop), the drive signal Dv is not output.

[0029] The rising transition period setting circuit TFUR outputs a predetermined rising transition period setting signal Tfur. The value of the rising transition period setting signal Tfur is set to be equal to or less than the value of the peak rising period setting signal Tur. The falling transition period setting circuit TFKR outputs a predetermined falling transition period setting signal Tfkr. The value of the falling transition period setting signal Tfkr is set to be equal to or less than the value of the peak falling period setting signal Tkr.

[0030] The feed speed setting circuit FR receives the forward feed peak value setting signal Wsr, the reverse feed peak value setting signal Wrr, the electrode negative polarity period reverse feed peak value setting signal Wnr, the timer signal Tm, the rising change period setting signal Tfur, and the falling change period setting signal Tfkr as inputs, performs the following processing, and outputs a feed speed setting signal Fr: 1) From the start of the peak rising period Tu of the timer signal Tm=1, during the rising change period Tfu determined by the rising change period setting signal Tfur, outputs the feed speed setting signal Fr which changes from the value of the electrode negative polarity period reverse feed peak value setting signal Wnr to the value of the forward feed peak value setting signal Wsr. 2) Subsequently, during the period until the timer signal Tm=2 (peak period Tp) ends, outputs the forward feed peak value setting signal Wsr as the feed speed setting signal Fr. 3) Subsequently, during the falling change period Tfk determined by the falling change period setting signal Tfkr from the start of the peak falling period Tk of the timer signal Tm=3, the feed speed setting signal Fr that changes from the value of the forward feed peak value setting signal Wsr to the value of the reverse feed peak value setting signal Wrr is output. 4) Subsequently, during the period until the timer signal Tm=4 (base period Tb) ends, the reverse feed peak value setting signal Wrr is output as the feed speed setting signal Fr. 5) Subsequently, during the electrode negative polarity Ten of the timer signal Tm=5, the electrode negative polarity period reverse feed peak value setting signal Wnr is output as the feed speed setting signal Fr. 6) The above 1) to 5) are repeated.

[0031] The feed control circuit FC receives as input the feed speed setting signal Fr and a start signal On from the robot control device RC (described later), and outputs a feed control signal Fc to the feed motor WM for feeding the welding wire 1 at the value of the feed speed setting signal Fr when the start signal On is at a high level (welding start), and outputs a feed control signal Fc to the feed motor WM for stopping feeding when the start signal On is at a low level.

[0032] The electrode negative polarity current ratio calculation circuit RND receives the welding current detection signal Id and the timer signal Tm as inputs, calculates the percentage of the value obtained by integrating the welding current detection signal Id during the electrode negative polarity period Ten of timer signal Tm=5 to the value obtained by integrating the welding current detection signal Id during the pulse period Tf of timer signal Tm=1 to 5, and outputs this as an electrode negative polarity current ratio calculation signal Rnd. Therefore, the electrode negative polarity current ratio Rn [%] is the percentage of the electrode negative polarity current Ien in the average value of the welding current Iw.

[0033] The electrode negative polarity current ratio setting circuit RNR outputs a predetermined electrode negative polarity current ratio setting signal Rnr.

[0034] The electrode negative polarity current setting circuit INR receives the electrode negative polarity current ratio calculation signal Rnd and the electrode negative polarity current ratio setting signal Rnr as inputs, performs modulation control so that both values ​​are equal, and outputs the electrode negative polarity current setting signal Inr.

[0035] The robot control device RC moves a robot (not shown) in accordance with a pre-taught work program, and outputs a start signal On to command the start or stop of welding.

[0036] 2 is a timing chart of signals in the welding apparatus of FIG. 1 , illustrating a method for controlling AC pulse arc welding according to an embodiment of the present disclosure. (A) in FIG. 2 shows the change over time in welding current Iw, (B) in FIG. 2 shows the change over time in welding voltage Vw, (C) in FIG. 2 shows the change over time in welding wire feed speed Fw, and (D) in FIG. 2 shows the change over time in polarity switching signal Spn. The operation of each signal will be described below with reference to FIG. 2.

[0037] The welding current Iw shown in Fig. 1A and the welding voltage Vw shown in Fig. 1B represent electrode positive polarity EP when they are positive values ​​above 0, and represent electrode negative polarity EN when they are negative values ​​below 0. The feed speed Fw shown in Fig. 1C represents a forward feed state in which the wire is fed forward in a direction toward the base metal when it is positive values ​​above 0, and a reverse feed state in which the wire is fed backward in a direction away from the base metal when it is negative values ​​below 0.

[0038] At time t1, as shown in FIG. 1D, the polarity switching signal Spn changes to a high level, and the period from time t1 to time t5 becomes an electrode positive polarity period Tep. During a predetermined peak rise period Tu from time t1 to time t2, as shown in FIG. 1A, a peak rise current Iu flows, increasing from a base current Ib, which is modulated by current modulation, to a peak current Ip, which is modulated by current modulation, as shown in FIG. 1B. As shown in FIG. 1B, a peak rise voltage, which increases from a base voltage Vb to a peak voltage Vp, is applied between the welding wire and the base metal. During a predetermined rise change period Tfu from time t1 to time t11, as shown in FIG. 1C, the feed rate Fw changes from the reverse feed peak value Wn of the electrode negative polarity period to the forward feed peak value Ws. The start of the rise change period Tfu is synchronized with the start of the peak rise period Tu. The rise change period Tfu is a period shorter than the peak rise period Tu. The peak rise period Tu is set by the peak rise period setting signal Tur of FIG. 1. The base current Ib is set by the base current setting signal Ibr of FIG. 1. The peak current Ip is set by the peak current setting signal Ipr of FIG. 1. The rise change period Tfu is set by the rise change period setting signal Tfur of FIG. 1. The electrode negative polarity period reverse transmission peak value Wn is set by the electrode negative polarity period reverse transmission peak value setting signal Wnr of FIG. 1. The forward transmission peak value Ws is set by the forward transmission peak value setting signal Wsr of FIG. 1.

[0039] During a predetermined peak period Tp from time t2 to t3, as shown in FIG. 1A, a peak current Ip is supplied by current modulation control, and as shown in FIG. 1B, a peak voltage Vp is applied between the welding wire and the base metal. During the period from time t11 to t3, as shown in FIG. 1C, the feed rate Fw is equal to the forward feed peak value Ws. The peak period Tp is set by the peak period setting signal Tpr shown in FIG. 1.

[0040] During a predetermined peak fall period Tk from time t3 to t4, as shown in FIG. 1A, a peak fall current Ik is supplied, decreasing from a peak current Ip, which is modulated by current modulation, to a base current Ib, which is modulated by current modulation. As shown in FIG. 1B, a peak fall voltage, which decreases from a peak voltage Vp to a base voltage Vb, is applied between the welding wire and the base metal. During a predetermined fall change period Tfk from time t3 to t31, as shown in FIG. 1C, the feed speed Fw changes from the forward feed peak value Ws to the reverse feed peak value Wr. The start of the fall change period Tfk is synchronized with the start of the peak fall period Tk. The fall change period Tfk is a period that is equal to or shorter than the peak fall period Tk. The peak fall period Tk is set by the peak fall period setting signal Tkr in FIG. 1. The fall change period Tfk is set by the fall change period setting signal Tfkr in FIG. 1. The reverse transmission peak value Wr is set by the reverse transmission peak value setting signal Wnr in FIG.

[0041] During a predetermined base period Tb from time t4 to t5, as shown in FIG. 1A, a base current Ib subjected to current modulation control is supplied, and as shown in FIG. 1B, a base voltage Vb is applied between the welding wire and the base metal. During a period from time t31 to t5, as shown in FIG. 1C, the feed rate Fw is equal to the reverse feed peak value Wr. The base period Tb is set by the base period setting signal Tbr shown in FIG. 1.

[0042] At time t5, as shown in FIG. 1D, the polarity switching signal Spn changes to a low level, and the period from time t5 to t6 becomes an electrode negative polarity period Ten. During the predetermined electrode negative polarity period Ten from time t5 to t6, as shown in FIG. 1A, a negative electrode negative polarity current Ien is supplied under current modulation control. The electrode negative polarity current Ien drops to a negative base current Ib just before the end of the electrode negative polarity period Ten. As shown in FIG. 1B, a negative electrode negative polarity voltage Ven is applied between the welding wire and the base metal. At the same time, as shown in FIG. 1C, the feed rate Fw becomes the electrode negative polarity period reverse feed peak value Wn. Therefore, the welding wire is reverse fed at least during the base period Tb and the electrode negative polarity period Ten. The electrode negative polarity period Ten is set by the electrode negative polarity period setting signal Tnr in FIG. 1. The electrode negative polarity current Ien is set by the electrode negative polarity current setting signal Inr in FIG. 1.

[0043] Numerical examples of the above parameters are shown below: Tu = 1 ms, Tp = 1.5 ms, Tk = 1 ms, Tb = 1.5 ms, Ten = 1.3 ms Ip = 350 to 500 A, Ib = 50 to 150 A, Ien = 350 to 500 A Tfu = 0.5 to 1 ms, Tfk = 0.5 to 1 ms Ws = 50 m / min, Wr = -20 m / min, Wn = -30 m / min

[0044] The effects of this embodiment are described below. According to this embodiment, a welding wire is fed, and during an electrode positive polarity period, a peak rise current that rises from a base current value to a peak current value during a peak rise period is passed, a peak current is passed during the peak period, a peak fall current that falls from the peak current value to the base current value during a peak fall period is passed, a base current is passed during the base period, and an electrode negative polarity current is passed during an electrode negative polarity period. These current passes are repeated as one pulse cycle to weld. In this method, the welding wire is fed forward and backward, and is fed backward at least during the base period and the electrode negative polarity period. A droplet is formed at the tip of the welding wire by passing the electrode negative polarity current and the peak current. By feeding the welding wire backward during the following base period, an upward force is continuously applied to the droplet during the base period, thereby ensuring that the droplet is transferred to the molten pool. As a result, even if the droplet size increases during AC pulse arc welding, a one-droplet-per-pulse-cycle transfer state can be consistently maintained, thereby achieving good welding quality. Furthermore, since the welding wire is fed in reverse when droplets are gradually formed by the passage of the electrode negative polarity current, it is possible to suppress the occurrence of a short circuit between the welding wire and the base metal, and it is possible to maintain a stable welding state.

[0045] More preferably, according to this embodiment, the welding wire feed speed starts changing from the reverse feed peak value to the forward feed peak value at the start of the peak rise period, and starts changing from the forward feed peak value to the reverse feed peak value at the start of the peak fall period. By synchronizing the start of the peak rise period with the start of the change from the reverse feed peak value to the forward feed peak value, it is possible to reliably form a droplet of an appropriate size during the peak period. Furthermore, by synchronizing the start of the peak fall period with the start of the change from the forward feed peak value to the reverse feed peak value, a strong upward force can be applied to the droplet, thereby reliably detaching the droplet and transferring it to the molten pool.

[0046] More preferably, in this embodiment, the change period from the forward feed peak value to the reverse feed peak value is equal to or shorter than the peak fall period, so that the upward force acting on the droplet can be further strengthened, and the droplet can be more reliably separated and transferred to the molten pool.

[0047] More preferably, according to this embodiment, the absolute value of the reverse feed peak value is set to a value greater than that during the electrode negative polarity period, thereby more reliably preventing a short circuit between the welding wire and the base metal during the electrode negative polarity period.

[0048] More preferably, according to this embodiment, the arc length is controlled by modulating at least the peak current, and the electrode negative polarity current ratio is maintained at a set value by modulating the electrode negative polarity current. In this way, the pulse period is set to a predetermined value, so the average feed speed can be maintained at a set value. When the peak current is modulated, the electrode negative polarity current ratio changes. In this case, the electrode negative polarity current ratio can be maintained at a set value by modulating the electrode negative polarity current. As a result, it is possible to suppress fluctuations in the average feed speed and the electrode negative polarity current ratio, which can cause fluctuations in the bead appearance and penetration shape.

[0049] 1 Welding wire 2 Base material 3 Arc 4 Welding torch 5 Feed roll DV Drive circuit Dv Drive signal EI Current error amplifier circuit Ei Current error amplifier signal EV Voltage error amplifier circuit Ev Voltage error amplifier signal FC Feed control circuit Fc Feed control signal FR Feed speed setting circuit Fr Feed speed setting signal Fw Feed speed Ib Base current Ibr Base current setting signal IC Current modulation circuit ID Welding current detection circuit Id Welding current detection signal Ien Electrode negative polarity current Ik Peak fall current InR Electrode negative polarity current setting circuit Inr Electrode negative polarity current setting signal Ip Peak current Ipr Peak current setting signal IR Welding current setting circuit Ir Welding current setting signal Iu Peak rise current Iw Welding current MC Power control circuit On Start signal PS Welding power source RC Robot controller Rn Electrode negative polarity current ratio RND Electrode negative polarity current ratio calculation circuit Rnd Electrode negative polarity current ratio calculation signal RNR Electrode negative polarity current ratio setting circuit Rnr Electrode negative polarity current ratio setting signal SPN Polarity switching circuit Spn Polarity switching signal Tb Base period TBR Base period setting circuit Tbr Base period setting signal Ten Electrode negative polarity period Tep Electrode positive polarity period Tfk Falling change period TFKR Falling change period setting circuit Tfkr Falling change period setting signal Tfu Rising change period TFUR Rising change period setting circuit Tfur Rising change period setting signal Tk Peak falling period TKR Peak falling period setting circuit Tkr Peak falling period setting signal TNR Electrode negative polarity period setting circuit Tnr Electrode negative polarity period setting signal Tp Peak period TPR Peak period setting circuit Tpr Peak period setting signal Tu Peak rise period TUR Peak rise period setting circuit Tur Peak rise period setting signal VAV Welding voltage averaging circuit Vav Welding voltage average value signal Vb Base voltage VDWelding voltage detection circuit Vd Welding voltage detection signal Vp Peak voltage VR Welding voltage setting circuit Vr Welding voltage setting signal Vw Welding voltage WM Feeding motor Wn Electrode negative polarity period reverse feed peak value WNR Electrode negative polarity period reverse feed peak value setting circuit Wnr Electrode negative polarity period reverse feed peak value setting signal Wr Reverse feed peak value WRR Reverse feed peak value setting circuit Wrr Reverse feed peak value setting signal Ws Forward feed peak value WSR Forward feed peak value setting circuit Wsr Forward feed peak value setting signal

Claims

1. A method for controlling AC pulse arc welding, comprising: feeding a welding wire; during an electrode positive polarity period, passing a peak rise current that rises from a base current value to a peak current value during a peak rise period, passing the peak current during the peak period, passing a peak fall current that falls from the peak current value to the base current value during a peak fall period, passing the base current during the base period; and passing an electrode negative polarity current during an electrode negative polarity period; and repeating the passing of current during the electrode positive polarity period and the electrode negative polarity period as one pulse cycle, wherein the feeding of the welding wire includes repeatedly feeding the welding wire in a forward direction and a reverse direction, and the reverse feeding of the welding wire is performed at least during the base period and the electrode negative polarity period.

2. The AC pulse arc welding control method according to claim 1, wherein the welding wire feed speed starts to change from a reverse feed peak value to a forward feed peak value at a start of the peak rise period, and starts to change from the forward feed peak value to the reverse feed peak value at a start of the peak fall period.

3. The AC pulse arc welding control method according to claim 2, wherein the period of change from the forward feed peak value to the reverse feed peak value is equal to or shorter than the peak fall period.

4. The AC pulse arc welding control method according to claim 3, wherein the absolute value of the reverse feed peak value is set to a value greater during the electrode negative polarity period than during the base period.

5. An AC pulse arc welding control method according to any one of claims 1 to 4, wherein arc length control is performed by modulating and controlling at least the peak current, and the electrode negative polarity current ratio is maintained at a set value by modulating and controlling the electrode negative polarity current.

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