Ac pulse arc welding control method and ac pulse arc welding power supply

Abstract

To obtain excellent welding quality by always maintaining one pulse period and one droplet transfer state even when a welding state is fluctuated in AC pulse arc welding.SOLUTION: In an electrode positive polarity period, applying a transition current that increases from a base current value to a peak current value, applying the peak current, applying a transition current that decreases from the peak current value to the base current value, applying the base current, and applying an electrode negative polarity current, and repeating these applications of a welding current Iw as one pulse cycle, the wire feed rate Fw is higher than 0m / min during the peak period from t2 to t3, equal to or lower than 0m / min during the base period from t4 to t5, and equal to or higher than 0m / min during the negative polarity period from t5 to t6.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for controlling AC pulse arc welding, which involves feeding a welding wire to weld, and to an AC pulse arc welding power source. [Background technology]

[0002] Pulse arc welding, which uses a welding wire to weld steel, is used for welding materials such as steel. To increase welding speed and improve welding efficiency, the melting rate of the welding wire must be increased. By providing a negative electrode polarity period, AC pulse arc welding can increase the melting rate of the welding wire 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 applied, which rises from the base current value to the peak current value during the peak rise period, a peak current is applied during the peak period, a peak fall current is applied, which falls from the peak current value to the base current value during the peak fall period, a base current is applied during the base period, and a negative electrode polarity current is applied during the negative electrode polarity period. These current applications are repeated as one pulse cycle to perform welding. Pulse arc welding minimizes spatter and produces a beautiful bead appearance by achieving one droplet transfer per pulse cycle.

[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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6123069 Summary of the Invention [Problem to be solved by the invention]

[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. As a result, in conventional AC pulsed arc welding, the transfer state of one droplet per pulse cycle deviates, resulting in a problem of poor welding quality.

[0006] Therefore, an object of the present invention is to provide an AC pulse arc welding control method and an AC pulse arc welding power source that can always maintain, for example, a one-droplet-per-pulse-cycle state to obtain good welding quality. [Means for solving the problem]

[0007] A first aspect of the present invention provides an AC pulse arc welding control method for welding by feeding a welding wire, and 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, repeating these current passes as one pulse period, characterized in that a feeding speed of the welding wire is greater than 0 m / min during the peak period, is equal to or less than 0 m / min during the base period, and is equal to or greater than 0 m / min during the electrode negative polarity period.

[0008] As an example, the AC pulse arc welding control method of the present invention is characterized in that the feed rate during the electrode negative polarity period is set in accordance with the length of the electrode negative polarity period.

[0009] As an example, the AC pulse arc welding control method of the present invention is characterized in that the electrode negative polarity current has a pulse waveform.

[0010] As an example, the AC pulse arc welding control method of the present invention is characterized in that a change from the feed rate in the electrode negative polarity period to the feed rate in the peak period starts at a start of the peak rise period, a change from the feed rate in the peak period to the feed rate in the base period starts at a start of the peak fall period, and the change ends before an end of the peak fall period.

[0011] As an example, the AC pulse arc welding control method of the present invention is characterized in that 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.

[0012] According to a second aspect of the present invention, there is provided an AC pulse arc welding power supply that feeds a welding wire, and during an electrode positive polarity period, passes a peak rise current that rises from a base current value to a peak current value during a peak rise period, passes the peak current during the peak period, passes a peak fall current that falls from the peak current value to the base current value during a peak fall period, passes the base current during the base period, and passes an electrode negative polarity current during an electrode negative polarity period, repeating these current passes as one pulse period to perform welding, characterized in that the AC pulse arc welding power supply controls the welding wire feed speed so that it is greater than 0 m / min during the peak period, is equal to or less than 0 m / min during the base period, and is equal to or greater than 0 m / min during the electrode negative polarity period. [Effects of the Invention]

[0013] According to the above configuration, for example, with respect to the AC pulse arc welding control method and AC pulse arc welding power source, a one-pulse-period, one-droplet transfer state can be constantly maintained, thereby obtaining good welding quality. [Brief explanation of the drawings]

[0014] [Figure 1]1 is a block diagram of an AC pulse arc welding power supply PS according to an embodiment of the present invention. [Figure 2] 2 is a timing chart of signals in the AC pulse arc welding power supply PS of FIG. 1, illustrating a method for controlling AC pulse arc welding according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] 1 is a block diagram of an AC pulse arc welding power supply PS according to an embodiment of the present invention. The welding device is mainly composed of an AC pulse arc welding power supply PS surrounded by a dashed line, a robot control device RC, a robot (not shown), etc. Each block will be described below with reference to the diagram.

[0017] The AC pulsed arc welding power supply PS consists of the following blocks:

[0018] The power control circuit MC is connected to a three-phase 200V or other commercial AC 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.

[0019] The feed motor WM is driven to rotate 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 metal 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 metal 2, and a welding current Iw flows. In the following description, when the feed speed Fw>0 m / min, the welding wire 1 is fed forward in a direction approaching the base metal 2; when Fw=0 m / min, feeding is stopped; and when Fw<0 m / min, the welding wire 1 is fed backward in a direction away from the base metal 2.

[0020] 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 this 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 amplification 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.

[0021] The current modulation circuit IC receives the voltage error amplified signal Ev as an input, 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.

[0022] 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.

[0023] The electrode negative polarity period setting circuit TNR outputs a predetermined electrode negative polarity period setting signal Tnr.

[0024] The welding current setting circuit IR receives as input the peak rise period setting signal Tur, the peak period setting signal Tpr, the peak fall period 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 control setting signal Incr (described later), 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, a timer signal Tm=1 is output, and the peak rise current Iu, which rises from the value of the base current setting signal Ibr to the value of the peak current setting signal Ipr, is output as the welding current setting signal Ir. 2) Subsequently, during the peak period Tp determined by the peak period setting signal Tpr, the timer signal Tm=2 is output, and the peak current setting signal Ipr is output 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, the 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 control setting signal Incr is output as the welding current setting signal Ir, and just before the end of the electrode negative polarity period Ten, the welding current setting signal Ir that rises to the value of the base current setting signal Ibr is output. 6) Repeat steps 1) to 5) above.

[0025] The polarity switching circuit SPN receives the timer signal Tm as 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 period Tep) and at a low level when the timer signal Tm=5 (electrode negative polarity period Ten).

[0026] The peak period feed rate setting circuit FPR outputs a peak period feed rate setting signal Fpr having a value greater than a predetermined value of 0 m / min, and the base period feed rate setting circuit FBR outputs a base period feed rate setting signal Fbr having a value equal to or less than a predetermined value of 0 m / min.

[0027] The electrode negative polarity period feed rate setting circuit FNR receives the electrode negative polarity period setting signal Tnr as an input and outputs an electrode negative polarity period feed rate setting signal Fnr of 0 m / min or more that is set in accordance with this 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 the robot control device RC (described later), and performs pulse width modulation control based on the current error amplification signal Ei when the activation signal On is high (welding starts) 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 stops), 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 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 less than the value of the peak falling period setting signal Tkr.

[0030] The feed speed setting circuit FR receives the peak period feed speed setting signal Fpr, the base period feed speed setting signal Fbr, the electrode negative polarity period feed speed setting signal Fnr, 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 the feed speed setting signal Fr. 1) During the rising change period Tfu determined by the rising change period setting signal Tfur from the start of the peak rising period Tu of the timer signal Tm=1, the feed speed setting signal Fr is output, which changes from the value of the electrode negative polarity period feed speed setting signal Fnr to the value of the peak period feed speed setting signal Fpr. 2) Subsequently, the peak period feed speed setting signal Fpr is output as the feed speed setting signal Fr during the period until the timer signal Tm=2 (peak period Tp) ends. 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 feeding speed setting signal Fr that changes from the value of the peak period feeding speed setting signal Fpr to the value of the base period feeding speed setting signal Fbr is output. 4) Subsequently, the base period feed speed setting signal Fbr is output as the feed speed setting signal Fr during the period until the timer signal Tm=4 (base period Tb) ends. 5) Subsequently, during the electrode negative polarity period Ten of the timer signal Tm=5, the electrode negative polarity period feed speed setting signal Fnr is output as the feed speed setting signal Fr. 6) Repeat steps 1) to 5) above.

[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 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 electrode negative polarity current control setting circuit INCR receives the electrode negative polarity current setting signal Inr and outputs an electrode negative polarity current control setting signal Incr having a pulse waveform of one or more periods with this value as the average value.

[0036] The robot control device RC moves a robot (not shown) in accordance with a work program that has been taught to it in advance, and outputs a start signal On that commands the start or stop of welding.

[0037] 2 is a timing chart of each signal in the AC pulse arc welding power supply PS of FIG. 1, which illustrates an AC pulse arc welding control method according to an embodiment of the present invention. (A) in FIG. 2 shows the change over time in the welding current Iw, (B) in FIG. 2 shows the change over time in the welding voltage Vw, (C) in FIG. 2 shows the change over time in the welding wire feed speed Fw, and (D) in FIG. 2 shows the change over time in the polarity switching signal Spn. The operation of each signal will be explained below with reference to the diagram.

[0038] The welding current Iw shown in Fig. 1A and the welding voltage Vw shown in Fig. 1B are positive values ​​above 0 when the electrode has positive polarity EP, and negative values ​​below 0 when the electrode has negative polarity EN. The feed speed Fw shown in Fig. 1C is a positive value above 0 when the wire is fed forward toward the base metal, is 0 when the wire is stopped, and is a negative value below 0 when the wire is fed backward away from the base metal.

[0039] In the figure, the value of the peak period feed speed setting signal Fpr in Figure 1 is a positive value greater than 0 m / min, and the welding wire is fed forward. The value of the base period feed speed setting signal Fbr in Figure 1 is a negative value less than 0 m / min, and the welding wire is fed backward. The value of the electrode negative polarity period feed speed setting signal Fnr in Figure 1 is 0 m / min, and the welding wire feeding stops.

[0040] At time t1, as shown in (D) of the figure, the polarity switching signal Spn changes to a high level, and the period from time t1 to t5 becomes an electrode positive polarity period Tep. During a predetermined peak rise period Tu from time t1 to t2, as shown in (A) of the figure, a peak rise current Iu increases from a base current Ib that is current modulation controlled to a peak current Ip that is current modulation controlled, and as shown in (B) of the figure, a peak rise voltage that 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 t11, as shown in (C) of the figure, the feed rate Fw changes from the value of the electrode negative polarity period feed rate Fn to the value of the peak period feed rate Fp. 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 feed rate Fn is set by the electrode negative polarity period feed rate setting signal Fnr of FIG. 1. The peak period feed rate Fp is set by the peak period feed rate setting signal Fpr of FIG. 1.

[0041] During a predetermined peak period Tp from time t2 to t3, as shown in FIG. 1(A), a peak current Ip is supplied by current modulation control, and as shown in FIG. 1(B), 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. 1(C), the feed rate Fw is equal to the peak period feed rate Fp, so the welding wire is fed in the forward direction. The peak period Tp is set by the peak period setting signal Tpr in FIG. 1.

[0042] During a predetermined peak fall period Tk from time t3 to t4, as shown in FIG. 1A, a peak fall current Ik is applied, decreasing from a peak current Ip, which is current modulation controlled, to a base current Ib, which is current modulation controlled. 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 rate Fw changes from the peak period feed rate Fp to the base period feed rate Fb. 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 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 base period feed rate Fb is set by the base period feed rate setting signal Fbr shown in FIG.

[0043] During a predetermined base period Tb from time t4 to t5, as shown in FIG. 1(A), a base current Ib that is current modulation controlled is supplied, and as shown in FIG. 1(B), a base voltage Vb is applied between the welding wire and the base metal. During the period from time t31 to t5, as shown in FIG. 1(C), the feed speed Fw is equal to the base period feed speed Fb, so the welding wire is fed in reverse. When the value of the base period feed speed Fb is 0, feeding is stopped. The base period Tb is set by the base period setting signal Tbr in FIG. 1.

[0044] At time t5, as shown in (D) of the figure, the polarity switching signal Spn changes to low level, and the period from time t5 to t6 becomes the electrode negative polarity period Ten. During the predetermined electrode negative polarity period Ten from time t5 to t6, as shown in (A) of the figure, an electrode negative polarity current Ien having a negative pulse waveform that is current modulation controlled flows, and the electrode negative polarity current Ien rises to a negative base current Ib just before the end of the electrode negative polarity period Ten. As shown in (B) of the figure, an electrode negative polarity voltage Ven having a negative pulse waveform is applied between the welding wire and the base metal. At the same time, as shown in (C) of the figure, the feed speed Fw becomes the value of the electrode negative polarity period feed speed Fn. In the figure, Fn = 0, so feeding is stopped. When Fn > 0, forward feeding is performed. The value of Fn is set according to the length of the electrode negative polarity period Ten. The electrode negative polarity period Ten is set by the electrode negative polarity period setting signal Tnr of FIG. 1. The electrode negative polarity current Ien is set by the electrode negative polarity current control setting signal Incr shown in FIG.

[0045] Examples of values ​​for the above parameters are shown below: Tu=1ms, Tp=1.5ms, Tk=1ms, Tb=1.5ms, Ten=1.3ms, Ip=350-500A, Ib=50-150A, Ien (average value)=350-500A, Tfu=0.5-0.9ms, Tfk=0.5-0.9ms, Fp=20-50m / min, Fb=0--20m / min, Fn=0-10m / min

[0046] The effects of this embodiment will be described below. According to this embodiment, in an AC pulse arc welding control method, 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, and these current passes are repeated as one pulse period to perform welding. In this method, the welding wire feed speed is greater than 0 m / min during the peak period, is less than 0 m / min during the base period, and is greater than 0 m / min during the electrode negative polarity period. During the peak period, the welding wire is fed at a feed speed greater than 0 m / min, resulting in a forward feed state, and a droplet is formed at the tip of the welding wire due to the passing of the peak current. During the subsequent base period, the welding wire is fed at a feed rate of 0 m / min or less, resulting in a stop or reverse feed state, which applies an upward force to the droplets. This promotes droplet detachment and ensures reliable transfer to the molten pool. Furthermore, during the process of droplet formation during the electrode negative polarity period, the welding wire is fed at a feed rate of 0 m / min or more, resulting in a stop or forward feed state, which prevents the droplets from becoming too large. As a result, even if the droplet size increases in AC pulse arc welding, the one-droplet-per-pulse-cycle transfer state can always be maintained, resulting in good welding quality.

[0047] More preferably, according to this embodiment, the feed rate during the electrode negative polarity period is set in accordance with the length of the electrode negative polarity period. By setting the feed rate in accordance with the length of the electrode negative polarity period, the formation of droplets can be stabilized and the occurrence of short circuits with the molten pool can be suppressed, resulting in a good welding condition.

[0048] More preferably, according to this embodiment, the electrode negative polarity current has a pulse waveform. By making the electrode negative polarity current a pulse waveform, the welding state can be stabilized, and the state of droplet formation during the electrode negative polarity period can be improved.

[0049] More preferably, according to this embodiment, the change in the feed rate from the electrode negative polarity period to the peak period begins at the start of the peak rise period, the change in the feed rate from the peak period to the base period begins at the start of the peak fall period, and the change ends before the end of the peak fall period. Synchronizing the start of the peak rise period with the start of the feed rate change ensures that droplets of appropriate size are formed during the peak period. Furthermore, by synchronizing the start of the peak fall period with the start of the feed rate change and ending the feed rate change before the end of the peak fall period, a strong upward force is applied to the droplets, thereby more reliably transferring them to the molten pool.

[0050] 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.

[0051] Furthermore, according to this embodiment, the AC pulse arc welding power supply controls the welding wire feed speed so that it is greater than 0 m / min during the peak period, less than 0 m / min during the base period, and greater than 0 m / min during the electrode negative polarity period. The AC pulse arc welding power supply according to this embodiment achieves the above-mentioned effects. [Explanation of symbols]

[0052] 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, Fb: base period feed speed, FBR: base period feed speed setting circuit, Fbr: base period feed speed setting signal, FC: feed control circuit, Fc: feed control signal, Fn: electrode negative polarity period feed speed, FNR: electrode negative polarity period feed speed setting circuit, Fnr: electrode negative polarity period feed speed setting signal, Fp: peak period feed speed, FPR : Peak period feed speed setting circuit, Fpr: Peak period feed speed setting 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 falling current, InR: Electrode negative polarity current setting circuit, Inr: Electrode negative polarity current setting signal, INCR: Electrode negative polarity current control setting circuit, Incr: Electrode negative polarity current control 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 control device, 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, Te n: 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, Tm: timer 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, VD: Welding 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: Feeder motor,

Claims

1. 1. An AC pulse arc welding control method comprising: feeding a welding wire; during an electrode positive polarity period, supplying a peak rise current that rises from a base current value to a peak current value during a peak rise period, supplying the peak current during the peak period; supplying a peak fall current that falls from the peak current value to the base current value during a peak fall period; supplying the base current during the base period; and supplying an electrode negative polarity current during an electrode negative polarity period; and repeating these supply of currents as one pulse period to perform welding, the welding wire feed speed is greater than 0 m / min during the peak period, is less than or equal to 0 m / min during the base period, and is greater than or equal to 0 m / min during the electrode negative polarity period.

2. 2. The AC pulse arc welding control method according to claim 1, wherein the feed rate during the electrode negative polarity period is set in accordance with the length of the electrode negative polarity period.

3. 3. The AC pulse arc welding control method according to claim 1, wherein the electrode negative polarity current has a pulse waveform.

4. 3. The AC pulse arc welding control method according to claim 1, wherein a change from the feed rate in the electrode negative polarity period to the feed rate in the peak period starts at a start of the peak rise period, a change from the feed rate in the peak period to the feed rate in the base period starts at a start of the peak fall period, and the change ends before an end of the peak fall period.

5. 3. The AC pulse arc welding control method according to claim 1, wherein the arc length is controlled 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.

6. an AC pulse arc welding power supply that feeds a welding wire, and during an electrode positive polarity period, passes a peak rise current that rises from a base current value to a peak current value during a peak rise period, passes the peak current during the peak period, passes a peak fall current that falls from the peak current value to the base current value during a peak fall period, passes the base current during the base period, and passes an electrode negative polarity current during an electrode negative polarity period, and repeats these current passes as one pulse period to perform welding; the AC pulse arc welding power supply controls the welding wire feed speed to a value greater than 0 m / min during the peak period, to a value equal to or less than 0 m / min during the base period, and to a value equal to or greater than 0 m / min during the electrode negative polarity period.

Images