JP6396162B2 - Arc welding control method - Google Patents

Description

  The present invention relates to an arc welding control method for performing welding by generating a short circuit period and an arc period by performing forward / reverse feed control for alternately switching a feeding speed of a welding wire between a forward feed period and a reverse feed period. It is.

  In general consumable electrode arc welding, a welding wire that is a consumable electrode is fed at a constant speed, and an arc is generated between the welding wire and a base material to perform welding. In the consumable electrode type arc welding, the welding wire and the base material are often in a welding state in which a short circuit period and an arc period are alternately repeated.

  In order to further improve the welding quality, a method has been proposed in which welding is performed by periodically repeating forward and reverse feeding of the welding wire. In this welding method, the cycle between the short circuit and the arc can be set to a desired value by setting the cycle between the forward feed and the reverse feed of the feed speed. For this reason, if this welding method is carried out, it becomes possible to suppress the variation in the cycle between the short circuit and the arc and make it substantially constant, and perform welding with a small amount of spatter generation and a good bead appearance. Can do.

  However, in a welding method that repeats forward and reverse feeding speeds, due to disturbances such as the distance between the feeding tip and the base metal, irregular movement of the molten pool, and changes in the welding position, the short-circuit period to the arc period There are cases where the timing of transition and transition from the arc period to the short-circuit period does not occur at an appropriate timing. If it becomes like this, the period of a short circuit and an arc and the period of forward transmission and reverse transmission will become out of synchronization, and the period of a short circuit and an arc will vary. A method for returning the synchronization shift state to the original synchronization state is disclosed in Patent Document 1.

  In the invention of Patent Document 1, when a short-circuit does not occur before the feeding speed reaches a predetermined feeding speed during normal feeding of the welding wire and deceleration of the feeding speed, the periodic change is stopped. The feed speed is controlled to be constant at the first feed speed, and if a short circuit occurs during normal feed at the first feed speed, deceleration is started from the first feed speed and the periodic change is resumed. Welding.

Japanese Patent No. 4807474

  In the invention of Patent Document 1, when a short circuit does not occur at an appropriate timing, the feeding speed is switched to a constant feed speed, and when a short circuit occurs, the feeding speed is returned to the original periodic change. However, in this control, even if the occurrence timing of the short circuit is slightly changed due to disturbance, the cycle of the feeding speed is changed by itself, and the welding state may be unstable.

  Therefore, in the present invention, when the occurrence timing of a short circuit or an arc fluctuates in welding that periodically repeats the forward feed and the reverse feed of the feed speed, the cycle of the short circuit and the arc and the forward feed of the feed speed It is an object of the present invention to provide an arc welding control method capable of suppressing stable synchronization with the reverse feed cycle and performing stable welding.

In order to solve the above-described problems, the invention of claim 1
In the arc welding control method of performing welding by generating a short circuit period and an arc period by performing forward / reverse feed control for alternately switching the feed speed of the welding wire between forward feed and reverse feed,
When the period from when the feed rate is changed to the Seioku to the first reference point in feeding the reverse was the arc period, switching the feed rate to the positive feed, the Seioku in wherein when a transition to the shorted period to resume the normal and reverse feed control from feeding the contrary,
An arc welding control method characterized by the above.

In the invention of claim 2, the first reference time point is a time point when the phase of the feed speed reaches the first reference phase or a time point when the feed speed reaches the first reference feed speed.
The arc welding control method according to claim 1, wherein:

The invention of claim 3
In the arc welding control method of performing welding by generating a short circuit period and an arc period by performing forward / reverse feed control for alternately switching the feed speed of the welding wire between forward feed and reverse feed,
When the short-circuiting period is from the time when the feed speed is changed to the reverse feed to the second reference time during the normal feed, the feed speed is switched to the reverse feed and the reverse feed is being performed. When the arc period is started, the forward / reverse feed control is resumed from the forward feed,
An arc welding control method characterized by the above.

In the invention of claim 4, the second reference time point is a time point when the phase of the feeding speed reaches a second reference phase or a time point when the feeding speed reaches a second reference feeding speed.
The arc welding control method according to claim 3.

  According to the present invention, the forward / reverse feed control is continued for small fluctuations in the welding state that do not fall into the synchronized shift state, so that the forward / reverse feed control is not frequently interrupted as in the prior art. . Furthermore, in the present invention, for large fluctuations in the welding state that fall into a synchronized deviation state (occurrence of a long-term arc period or a long-term short-circuit period), the forward / reverse feed control is interrupted and the control is returned to the synchronized state, Thereafter, the forward / reverse feed control is resumed. For this reason, in this invention, it can suppress that it falls into a synchronous shift state with respect to the fluctuation | variation of the welding state by a disturbance, and can stabilize a welding state.

It is a block diagram of the welding power supply for implementing the arc welding control method which concerns on Embodiment 1 of this invention. It is a timing chart of each signal when a long-term arc period generate | occur | produces from the steady welding state in the welding power supply of FIG. 1 which shows the arc welding control method which concerns on Embodiment 1 of this invention. It is a timing chart of each signal when the long-term short-circuit period generate | occur | produces from the steady welding state in the welding power supply of FIG. 1 which shows the arc welding control method which concerns on Embodiment 1 of this invention.

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

[Embodiment 1]
FIG. 1 is a block diagram of a welding power source for carrying out an arc welding control method according to Embodiment 1 of the present invention. 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 a three-phase 200V, performs output control by inverter control or the like according to a drive signal Dv described later, and outputs an output voltage E. Although not shown, the power supply main circuit PM is driven by a primary rectifier that rectifies commercial power, a smoothing capacitor that smoothes the rectified direct current, and the drive signal Dv that converts the smoothed direct current to high-frequency alternating current. An inverter circuit, a high-frequency transformer that steps down the high-frequency alternating current to a voltage value suitable for welding, and a secondary rectifier that rectifies the stepped-down high-frequency alternating current into direct current.

  The reactor WL smoothes the output voltage E. The inductance value of the reactor WL is, for example, 200 μH.

  The feed motor WM receives a feed control signal Fc described later, and feeds the welding wire 1 at a feed speed Fw by periodically repeating forward feed and reverse feed. A motor with fast transient response is used as the feed motor WM. In order to increase the rate of change of the feeding speed Fw of the welding wire 1 and the reversal of the feeding direction, the feeding motor WM may be installed near the tip of the welding torch 4. In some cases, two feed motors WM are used to form a push-pull feed system.

  The welding wire 1 is fed through the welding torch 4 by the rotation of the feeding roll 5 coupled to the feeding motor WM, and an arc 3 is generated between the welding wire 1 and the base material 2. A welding voltage Vw is applied between the power feed tip (not shown) in the welding torch 4 and the base material 2, and a welding current Iw is conducted.

  The output voltage setting circuit ER outputs a predetermined output voltage setting signal Er. The output voltage detection circuit ED detects and smoothes the output voltage E and outputs an output voltage detection signal Ed.

  The voltage error amplification circuit EV receives the output voltage setting signal Er and the output voltage detection signal Ed, and amplifies an error between the output voltage setting signal Er (+) and the output voltage detection signal Ed (−). The voltage error amplification signal Ev is output. By this circuit, the welding power source is controlled at a constant voltage.

  The drive circuit DV receives the voltage error amplification signal Ev, performs PWM modulation control based on the voltage error amplification signal Ev, and outputs a drive signal Dv for driving the inverter circuit in the power supply main circuit PM. To do.

  The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The short circuit determination circuit SD receives the voltage detection signal Vd as described above, and when this value is less than the short circuit determination value (about 10 V), it determines that it is a short circuit period and becomes a high level, and when it is above, it is an arc period. And a short circuit determination signal Sd that is at a low level is output.

  The average feed speed setting circuit FAR outputs a predetermined average feed speed setting signal Far. The period setting circuit TFR outputs a predetermined period setting signal Tfr. The amplitude setting circuit WFR outputs a predetermined amplitude setting signal Wfr.

The feed speed setting circuit FR receives the average feed speed setting signal Far, the cycle setting signal Tfr, the amplitude setting signal Wfr, a long-term arc period determination signal Lta described later, and a long-term short-circuit period determination signal Lts described later. As an input, the following processing is performed and a feed speed setting signal Fr is output.
1) Until the long-term arc period discriminating signal Lta or the long-term short-circuit period discriminating signal Lts changes to a high level, it changes in advance to a positive / negative target shape at an amplitude Wf determined by the amplitude setting signal Wfr and a cycle Tf determined by the cycle setting signal Tfr. A feed speed setting signal Fr having a waveform obtained by shifting the trapezoidal wave to the forward feed side by the value of the average feed speed setting signal Far is output. Thereby, forward / reverse feed control for alternately switching between the forward feed period and the reverse feed period is performed.
2) When the long-term arc period determination signal Lta changes to High level during the processing of 1) above, the feed speed setting signal Fr is switched to a predetermined positive value (forward feed value), and then the short-circuit determination signal Sd is When the level changes to the high level (short circuit), the process returns to 1), and the forward / reverse feed control is resumed from the reverse feed period.
3) When the long-term short-circuit period determination signal Lts changes to High level during the processing of 1) above, the feed speed setting signal Fr is switched to a predetermined negative value (reverse feed value), and then the short-circuit determination signal Sd When the level changes to the low level (arc), the processing returns to 1) and the forward / reverse feed control is resumed from the forward feed period.

  The long-term arc period discriminating circuit LTA receives the feed speed setting signal Fr and the short-circuit discrimination signal Sd as inputs, and determines in advance a reverse feed period from the time when the feed speed setting signal Fr changes to the forward feed period. When the short circuit determination signal Sd is at the low level (arc) until the first reference time Tt1, the long-term arc period determination signal Lta that is at a high level for a short time is output. Here, the first reference time Tt1 is the time when the phase of the feed speed setting signal Fr reaches the predetermined first reference phase or the feed speed setting signal Fr reaches the predetermined first reference feed speed. It is time. When the long-term arc period determination signal Lta becomes a high level for a short time, the arc length fluctuates due to a disturbance, so that a short circuit that normally occurs during the forward feed period does not occur and the first reverse feed period during the subsequent reverse feed period does not occur. This shows that a long-term arc period in which a short circuit has not yet occurred even when the reference time point Tt1 is reached. When the long arc period occurs, there is a high possibility that the above-described forward feed period and reverse feed period of the feeding speed, and the short circuit period and the arc period are in a synchronized shift state.

  The long-term short-circuit period determination circuit LTS receives the feed speed setting signal Fr and the short-circuit determination signal Sd as inputs, and determines in advance from the time when the feed speed setting signal Fr changes to the reverse feed period. When the short circuit determination signal Sd is at a high level (short circuit) until the second reference time Tt2, a long-term short circuit period determination signal Lts that is a high level for a short time is output. Here, the second reference time Tt2 is the time when the phase of the feed speed setting signal Fr reaches a predetermined second reference phase or the feed speed setting signal Fr reaches the predetermined second reference feed speed. It is time. When the long-term short-circuit period determination signal Lts is at a high level for a short time, the molten pool fluctuates due to disturbance, so that an arc that normally occurs during the reverse feed period does not occur, and the second during the subsequent normal feed period. It shows that a long-term short-circuit period is reached in which no arc has yet occurred even when the reference time Tt2 is reached. When the long-term short-circuit period occurs, there is a high possibility that the above-described forward-feed period and reverse-feed period of the feed speed, and the short-circuit period and the arc period are synchronized.

  The feed control circuit FC receives the feed speed setting signal Fr and receives a feed control signal Fc for feeding the welding wire 1 at a feed speed Fw corresponding to the value of the feed speed setting signal Fr. It outputs to said feed motor WM.

  FIG. 2 is a timing chart of each signal when the long-term arc period is generated from the steady welding state in the welding power source of FIG. 1, showing the arc welding control method according to the first embodiment of the present invention. FIG. 4A shows the time change of the feeding speed Fw, FIG. 4B shows the time change of the welding current Iw, FIG. 4C shows the time change of the welding voltage Vw, and FIG. ) Shows the time change of the short-circuit determination signal Sd, FIG. 9E shows the time change of the long-term arc period determination signal Lta, and FIG. Hereinafter, the operation of each signal will be described with reference to FIG.

  As shown in FIG. 5A, the feed speed Fw is a forward feed period above 0 and a reverse feed period below. The forward feeding is to feed the welding wire 1 in a direction approaching the base material 2, and the reverse feeding is to feed in a direction away from the base material 2.

  The feed speed Fw shown in FIG. 6A is controlled to the value of the feed speed setting signal Fr output from the feed speed setting circuit FR of FIG. The feed speed setting signal Fr in the steady welding state before time t3 and after time t5 is a predetermined trapezoidal wave that changes into a positive / negative target shape at an amplitude Wf determined by the amplitude setting signal Wfr and a cycle Tf determined by the cycle setting signal Tfr. Is a waveform shifted to the forward feed side by the value of the average feed speed setting signal Far. For this reason, as shown in FIG. 6A, the feed speed Fw is determined by using the average feed speed Fa indicated by a broken line determined by the average feed speed setting signal Far as a reference line, and the target amplitude Wf and It becomes a trapezoidal wave-shaped feeding speed pattern determined in advance with the period Tf. That is, the amplitude above the reference line and the amplitude below the reference line have the same value, and the period above and below the reference line have the same value. The feeding speed Fw may be a sine wave or triangular wave feeding speed pattern.

  Here, when a trapezoidal wave of the feeding speed Fw is seen with 0 as a reference line, as shown in FIG. 5A, the forward feeding period Ts at times t1 to t2 is a predetermined forward feeding acceleration period and forward feeding, respectively. It is formed from a peak period, a forward feed peak value, and a forward feed deceleration period, and a reverse feed period Tr at times t2 to t3 is determined from a predetermined reverse feed acceleration period, reverse feed peak period, reverse feed peak value, and reverse feed deceleration period, respectively. It is formed.

Here, a method of calculating the feeding speed phase Ba (°) will be described. The phase Ba of the feeding speed is 0 ° at time t1, 180 ° at time t2, and 360 ° at time t3. The forward transmission period from time t1 to t2 is Ts (ms), and the reverse transmission period from time t2 to t3 is Tr (ms). The elapsed time Ta (ms) from the time t1, which is the start time of the cycle, is measured, and the feeding speed phase Ba can be calculated by the following equation.
When Ta ≦ Ts, Ba = (Ta / Ts) × 180
When Ta> Ts, Ba = ((Ta−Ts) / Tr) × 180 + 180

  In the drawing, the first reference time Tt1 is set during the reverse feed period acceleration period at times t21 and t41, and the second reference time Tt2 is set during the forward feed period acceleration period at time t11 and time t31. . The first reference time Tt1 is preferably set before and after the start time of the reverse feed peak period. The second reference time Tt2 is preferably set before and after the start time of the forward feed peak period. When the feed speed Fw is a sine wave or a triangular wave, the first reference time Tt1 is set before and after the peak value during the reverse feed period, and the second reference time Tt2 is set before and after the peak value during the forward feed period. It is desirable to set. The reason why such a setting is desirable is as follows. The first reference time point Tt1 is a time point for determining the long arc period, and as the time elapses from the peak value of the reverse feed period, the arc length becomes longer and longer due to the reverse feed, and the short circuit is less likely to occur. . The second reference time point Tt2 is a time point for determining the long-term short-circuit period. As time elapses from the peak value of the forward feed period, the welding wire is pushed into the molten pool by forward feed and the arc becomes more difficult to occur. is there.

  As shown in FIG. 5E, the long-term arc period determination signal Lta remains at the low level during the period before time t41. Further, as shown in FIG. 8F, the long-term short-circuit period determination signal Lts remains at the low level during the entire period in the figure. That is, in the same figure, it is a case where a long-term short circuit period has not occurred.

  During the steady welding state before time t3, a short circuit often occurs in the latter half of the forward feed peak period, and occurs at least during the forward feed deceleration period. In this figure, a short circuit occurs at time t12, which is the latter half of the forward feed peak period. Since the arc period is before the time t12, the welding current Iw gradually decreases as shown in FIG. 5B, and the welding voltage Vw is several tens of volts as shown in FIG. Arc voltage value. Also, as shown in FIG. 4D, the short circuit determination signal Sd is at the low level (arc).

  When a short circuit occurs at time t12, the welding voltage Vw rapidly decreases to a short circuit voltage value of several volts as shown in FIG. 10C, and in response to this, as shown in FIG. The signal Sd changes to a high level (short circuit). At the same time, the welding current Iw gradually increases as shown in FIG. As shown in FIG. 5A, from time t2, the feeding speed Fw is in the reverse feed period, and the welding wire 1 is fed backward.

  During the steady welding state, arcs often occur in the latter half of the reverse feed peak period, and at least occur during the reverse feed deceleration period. In the figure, an arc is generated at time t22, which is the latter half of the reverse feed peak period. As described above, at the time t21 which is the first reference time Tt1 set during the reverse acceleration period, the arc period does not continue from the start of the normal feed period at the time t1, so that FIG. As shown in E), the long-term arc period discrimination signal Lta remains at the low level. At time t22, when an arc is generated by the reverse feed and the pinch force generated by energizing the welding current Iw, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts as shown in FIG. As shown in FIG. 4D, the short circuit determination signal Sd changes to the low level (arc). At the same time, the welding current Iw gradually decreases as shown in FIG. The period from time t12 to t22 is a short circuit period, and the short circuit determination signal Sd is at a high level as shown in FIG.

  As shown in FIG. 5A, the welding wire 1 is fed back and the arc length is gradually increased because the feeding period is between the times t22 and t3. Since the normal feed period starts from time t3, the welding wire 1 is forward fed and the arc length is gradually shortened. As described above, at the time t31, which is the second reference time Tt2 set during the forward feed acceleration period, the short-circuit period is not continued from the start of the reverse feed period at the time t2, so FIG. As shown in F), the long-term short-circuit period determination signal Lts remains at the low level.

  Normally, a short circuit is caused by normal feeding during the normal feeding period from time t3 to t4. However, since a disturbance has occurred, the arc length fluctuates and becomes long and no short circuit occurs. From time t4, as shown in FIG. 5A, the feed speed Fw is in the reverse feed period, and the welding wire 1 is fed backward, so that the arc length becomes longer thereafter. If this state is left unattended, the arc period will continue for a long time. As a result, the entire period from the time t3 is the arc period, and the feed speed forward feed period and the reverse feed period, and the short-circuit period and the arc period fall into synchronization. Here, at time t41, which is the first reference time Tt1 when the short circuit is set in the reverse feed acceleration period, the arc period continues from the start time of the forward feed period at time t3, so that FIG. As shown, the long-term arc period determination signal Lta is at a high level for a short time.

  When the long-term arc period determination signal Lta becomes a high level for a short time at time t41, the feed speed Fw is switched from the reverse feed period to the normal feed period as shown in FIG. This is the forward feed value. Thereby, since the welding wire 1 is forwarded, the arc length is gradually shortened. This normal feeding state is continued until a short circuit occurs at time t5. The period from time t22 to t5 is the arc period, and the short circuit determination signal Sd is at the low level as shown in FIG. If the above-mentioned normal feed value is too small, the short circuit does not occur and the welding state becomes unstable. If it is too large, the short circuit occurs immediately but the short circuit state becomes unstable. Therefore, it is desirable that the forward feed value is set before and after the forward feed peak value in the steady welding state.

  When a short circuit occurs at time t5, the welding voltage Vw rapidly decreases to a short circuit voltage value of several volts as shown in FIG. 10C, and in response to this, as shown in FIG. The signal Sd changes to a high level (short circuit). At the same time, the welding current Iw gradually increases as shown in FIG. In response to the change of the short circuit determination signal Sd to the high level, as shown in FIG. 5A, the feeding speed Fw is switched to the reverse feed period, and returns to the normal / reverse feed control from the reverse feed period. To do. Therefore, an arc is generated during the reverse feed period from time t5 to t6, and the state returns to the steady welding state in which a short circuit occurs during the normal feed period from time t6 to t7.

  As described above, in the present embodiment, when a long arc period occurs due to a disturbance, the feeding speed is switched to the forward feeding state and continues until a short circuit occurs, and when the short circuit occurs, the forward / reverse feed control is performed. I am returning. This quickly returns to the steady welding state. At this time, in the prior art, it is determined whether or not the long arc period has occurred by the fact that a short circuit has not occurred until a specific point in time during the normal feeding period. For this reason, in the prior art, since it is determined that a long-term arc period has occurred due to a slight change in the welding state, the forward / reverse feed control is frequently interrupted. On the other hand, in the present embodiment, the occurrence of the long-term arc period is determined depending on whether the arc period continues from the start time of the forward feed period to the first reference time point of the reverse feed period. In this way, the forward / reverse feed control is interrupted only when there is a possibility of falling into a synchronization shift state. That is, the forward / reverse feed control is continued as much as possible, and the interruption of the forward / reverse feed control is minimized, so that the stability of the welding state is improved as a whole.

FIG. 3 is a timing chart of each signal when the long-term short-circuit period occurs from the steady welding state in the welding power source of FIG. 1, showing the arc welding control method according to the first embodiment of the present invention. FIG. 4A shows the time change of the feeding speed Fw, FIG. 4B shows the time change of the welding current Iw, FIG. 4C shows the time change of the welding voltage Vw, and FIG. ) Shows the time change of the short-circuit determination signal Sd, FIG. 9E shows the time change of the long-term arc period determination signal Lta, and FIG. This figure corresponds to FIG. 2 described above, and the description of the same operation will not be repeated. Hereinafter, the operation of each signal will be described with reference to FIG.

  In the figure, the forward feed period from time t1 to t2, the reverse feed period from time t2 to t3, and the forward feed period from time t3 to t4 are in a steady welding state, and therefore the description of the operation will not be repeated. That is, a short circuit occurs during the forward feed period from time t1 to t2, an arc occurs during the reverse feed period from time t2 to t3, and a short circuit occurs during the forward feed period from time t3 to t4. In the figure, since the long-term arc period does not occur, the long-term arc period discrimination signal Lta remains at the low level during the whole period as shown in FIG.

  Normally, an arc is generated by reverse feed during the reverse feed period from time t4 to time t5, but the weld pool fluctuates due to the occurrence of a disturbance, and no arc is generated. From time t5, as shown in FIG. 6A, the feeding speed Fw is a normal feeding period, and the welding wire 1 is normally fed. Therefore, the short-circuit period continues for a long time. As a result, the entire period from the time t4 becomes a short circuit period, and the feed speed forward feed period and the reverse feed period, and the short circuit period and the arc period fall into a synchronized shift state. Here, at the time t51, which is the second reference time Tt2 set in the forward acceleration period, the short-circuit period continues from the start of the reverse feed period at the time t4, so as shown in FIG. In addition, the long-term short-circuit period determination signal Lts becomes a high level for a short time.

  When the long-term short-circuit period determination signal Lts becomes a high level for a short time at time t51, the feed speed Fw is switched from the normal feed period to the reverse feed period as shown in FIG. This is the reverse value of the value. Thereby, since the welding wire 1 is reversely fed, the welding wire 1 is pulled up. This reverse feed state continues until an arc occurs at time t6. The period from time t32 to t6 is a short circuit period, and the short circuit determination signal Sd is at a high level as shown in FIG. If the above-mentioned reverse feed value is too small, the arc is not easily generated and the welding state becomes unstable. If it is too large, the arc is generated immediately but the arc state becomes unstable. Therefore, it is desirable that the reverse feed value is set before and after the reverse feed peak value in the steady welding state.

  When an arc is generated at time t6, the welding voltage Vw suddenly increases to an arc voltage value of several tens of volts as shown in FIG. 10C, and in response to this, as shown in FIG. The determination signal Sd changes to a low level (arc). At the same time, the welding current Iw gradually decreases as shown in FIG. In response to the change of the short circuit determination signal Sd to the Low level, as shown in FIG. 5A, the feeding speed Fw is switched to the normal feeding period, and the normal feeding period returns to the normal / reverse feeding control. To do. Therefore, a short circuit occurs during the forward feed period from time t6 to t7, and the state returns to the steady welding state in which an arc is generated during the reverse feed period from time t7 to t8.

  As described above, when a long-term short-circuit period occurs due to disturbance, the feed speed is switched to the reverse feed state until the arc is generated, and when the arc occurs, the normal / reverse feed control is restored. This quickly returns to the steady welding state. In the prior art, no corresponding control is performed for the occurrence of a long-term short circuit period. In the present embodiment, the occurrence of the long-term short-circuit period is determined depending on whether the short-circuit period continues from the start time of the reverse feed period to the second reference time point of the normal feed period. In this way, the forward / reverse feed control is interrupted only when there is a possibility of falling into a synchronization shift state. That is, the forward / reverse feed control is continued as much as possible, and the interruption of the forward / reverse feed control is minimized, so that the stability of the welding state is improved as a whole.

  According to the first embodiment described above, when the period from the time when the feeding speed is changed to the forward feeding period to the first reference time during the backward feeding period is the arc period, the feeding speed is forward fed. When the shift to the short-circuit period during normal feeding, normal / reverse feed control is resumed from the reverse feeding period. Furthermore, according to the first embodiment, when the period from the time when the feeding speed is changed to the reverse feeding period to the second reference time in the normal feeding period is a short-circuit period, the feeding speed is reversed. When the arc period is entered during reverse feed, the forward / reverse feed control is resumed from the forward feed period. Thus, in the present embodiment, the forward / reverse feed control is continued for small fluctuations in the welding state that do not fall into the synchronous shift state, so that the forward / reverse feed control is frequently interrupted as in the prior art. There is nothing. Furthermore, in the present embodiment, for large fluctuations in the welding state (occurrence of a long-term arc period or a long-term short-circuit period) that fall into a synchronous deviation state, the forward / reverse feed control is interrupted to return to the synchronous state. After that, forward / reverse feed control is resumed. For this reason, in this Embodiment, it can suppress that it falls into a synchronous shift state with respect to the fluctuation | variation of the welding state by disturbance, and can stabilize a welding state.

DESCRIPTION OF SYMBOLS 1 Welding wire 2 Base material 3 Arc 4 Welding torch 5 Feed roll Ba Feed speed phase DV Drive circuit Dv Drive signal E Output voltage ED Output voltage detection circuit Ed Output voltage detection signal ER Output voltage setting circuit Er Output voltage setting signal EV voltage error amplification circuit Ev voltage error amplification signal Fa average feeding speed FAR average feeding speed setting circuit Far average feeding speed setting signal FC feeding control circuit Fc feeding control signal FR feeding speed setting circuit Fr feeding speed setting Signal Fw Feeding speed Iw Welding current LTA Long-term arc period discriminating circuit Lta Long-term arc period discriminating signal LTS Long-term short-circuiting period discriminating circuit Lts Long-term short-circuiting period discriminating signal PM Power supply main circuit SD Short-circuiting discriminating circuit Sd Short-circuiting discriminating signal Ta Elapsed time Tf Period TFR Period setting circuit Tfr Period setting signal Tr Reverse transmission period Ts Normal transmission period Tt1 First reference Point Tt2 second reference point VD voltage detection circuit Vd voltage detection signal Vw welding voltage Wf amplitude WFR amplitude setting circuit Wfr amplitude setting signal WL reactor WM feed motor

Claims (4)

In the arc welding control method of performing welding by generating a short circuit period and an arc period by performing forward / reverse feed control for alternately switching the feed speed of the welding wire between forward feed and reverse feed,
When the period from when the feed rate is changed to the Seioku to the first reference point in feeding the reverse was the arc period, switching the feed rate to the positive feed, the Seioku in wherein when a transition to the shorted period to resume the normal and reverse feed control from feeding the contrary,
An arc welding control method characterized by the above. The first reference time point is a time point when the phase of the feeding speed reaches a first reference phase or a time point when the feeding speed reaches a first reference feeding speed.
The arc welding control method according to claim 1. In the arc welding control method of performing welding by generating a short circuit period and an arc period by performing forward / reverse feed control for alternately switching the feed speed of the welding wire between forward feed and reverse feed,
When the short-circuiting period is from the time when the feed speed is changed to the reverse feed to the second reference time during the normal feed, the feed speed is switched to the reverse feed and the reverse feed is being performed. when a transition to the arc period to resume the normal and reverse feed control from the Seioku,
An arc welding control method characterized by the above. The second reference time point is a time point when the phase of the feeding speed reaches a second reference phase or a time point when the feeding speed reaches a second reference feeding speed.
The arc welding control method according to claim 3.

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