JP5773477B2 - Arc welding control method - Google Patents

Description

  The present invention relates to an arc welding control method that can suppress instability of a welding state due to magnetic blowing.

  Consumable electrode type pulse arc welding is widely used for welding steel and the like. In this pulse arc welding, a peak current having a large current value that is greater than or equal to the critical value is applied during the peak period, and a base current having a small current value that is less than the critical value is applied during the base period. Welding is performed repeatedly. In pulse arc welding, since one droplet period is one droplet transfer state, the droplet transfer state is stable, so that the occurrence of spatter is small and a beautiful bead appearance can be obtained. Hereinafter, this pulse arc welding will be described with reference to the drawings.

  FIG. 4 is a general current / voltage waveform diagram in pulse arc welding. FIG. 4A shows the time change of the welding current Iw, and FIG. 4B shows the time change of the welding voltage Vw. Hereinafter, a description will be given with reference to FIG.

  During the peak period Tp from time t1 to t2, a peak current Ip having a large current value equal to or higher than the critical value is energized to transfer droplets from the welding wire as shown in FIG. ), A peak voltage Vp proportional to the arc length is applied between the welding wire and the base material. The critical value of a steel wire having a diameter of 1.2 mm is about 280A.

  During the base period Tb from time t2 to t3, as shown in FIG. 5A, the base current Ib having a small current value less than the critical value is energized in order to prevent the formation of droplets. ), The base voltage Vb is applied. Welding is performed by repeating the period from time t1 to t3 as one period (pulse period Tf).

  By the way, in order to perform good pulse arc welding, it is important to maintain the arc length at an appropriate value. In order to maintain the arc length at an appropriate value, the following arc length control (output control of the welding power source) is performed. The arc length is substantially proportional to the welding voltage average value Vav indicated by a broken line in FIG. For this purpose, the welding voltage average value Vav is detected, and the output for changing the welding current average value Iav indicated by the broken line in FIG. 5A so that the detected value becomes equal to the welding voltage set value corresponding to the appropriate arc length. Take control. When the welding voltage average value Vav is larger than the welding voltage set value, the arc length is longer than the appropriate value. Therefore, the welding current average value Iav is decreased to reduce the wire melting rate and shorten the arc length. To do. On the other hand, when the welding voltage average value Vav is smaller than the welding voltage set value, the arc length is shorter than the appropriate value, so the welding current average value Iav is increased to increase the wire melting rate and the arc length is increased. Like that. As the welding voltage average value Vav, a value (average value, smooth value) obtained by passing the welding voltage Vw through a low-pass filter is generally used. Further, as a means for changing the welding current average value Iav, changing the pulse period Tf is performed. That is, the pulse period Tf is feedback controlled (arc length control) so that the welding voltage average value Vav becomes equal to the welding voltage setting value. At this time, the peak period Tp, the peak current Ip, and the base current Ib are set to predetermined values. The peak period Tp is set to about 1.0 to 1.5 ms, the peak current Ip is set to about 500 to 600 A, and the base current Ib is set to about 20 to 60 A. The combination of the peak period Tp and the peak current Ip is called a unit pulse condition, and is set so that one droplet period is in a droplet transfer state. This arc length control method is called frequency modulation control. Other arc length control methods include pulse width modulation control. In the pulse width modulation control, the pulse period Tf, the peak current Ip, and the base current Ib are set to predetermined values, and the peak period Tp (pulse width) is feedback controlled so that the welding voltage average value Vav becomes equal to the voltage setting value. .

  In consumable electrode type arc welding including pulse arc welding, a magnetic field is formed around the arc by a welding current passing through the arc and the base material, and the arc may be deflected by receiving a force from the magnetic field. Such a state is generally called magnetic blow or arc blow. Whether magnetic blowing occurs depends on the form of the magnetic field formed by the welding current passed through the base material. When the welded part is away from the end of the base metal, the magnetic field is often formed in a symmetrical shape, so that the arc does not receive a biased force from the magnetic field, so magnetic blowing occurs. Hateful. On the other hand, when the welded part is close to the end of the base material, the magnetic field is formed in an asymmetric shape, so that the arc receives a force deviated from the magnetic field, and magnetic blown easily occurs. Therefore, magnetic blowing is likely to occur at the welding start portion and the welding end portion that are often near the end of the base material. Among consumable electrode arcs, pulse arc welding tends to generate magnetic blow. In pulse arc welding, a strong magnetic field is formed when the peak current Ip having a large current value is energized, and a weak magnetic field is formed when the base current Ib having a small current value is energized. In pulse arc welding, magnetic field blow tends to occur due to the fact that the change in strength of the magnetic field is large and the base current Ib is small, so that the arc is deflected as soon as it receives a force biased from the magnetic field. . Therefore, in pulse arc welding, arc deflection due to magnetic blowing is likely to occur during the base period Tb.

  FIG. 5 is a diagram showing an arc state when magnetic blowing occurs. As shown in FIG. 2A, a normal arc 3 is generated between the welding wire 1 and the base material 2. When magnetic blowing occurs in this state, as shown in FIG. 5B, the arc 3 is largely deflected by the force from the magnetic field, and the arc length becomes long. If the deflection is further increased, the arc cannot be maintained and an arc break occurs as shown in FIG. In pulse arc welding, since a large current is applied during the peak period, the arc is highly rigid and the arc hardly deflects even when a force from a magnetic field is applied. On the other hand, since a small current is applied during the base period, the arc rigidity is weak, and it is largely deflected by the force from the magnetic field. Therefore, it is almost during the base period that the magnetic blow occurs and the arc break occurs. When arc breaks due to magnetic blowing occur many times, the arc generation state becomes unstable, and a large amount of spatter is generated, and the bead appearance is remarkably deteriorated. Therefore, in pulse arc welding, it is important to suppress arc breaks due to magnetic blowing in order to obtain good welding quality.

  FIG. 6 is a current / voltage waveform diagram when magnetic blow occurs in pulse arc welding. FIG. 4A shows the time change of the welding current Iw, and FIG. 4B shows the time change of the welding voltage Vw. Hereinafter, a description will be given with reference to FIG.

  During the peak period Tp from time t1 to t2, a peak current Ip greater than the critical value is energized as shown in FIG. 6A, and a peak voltage approximately proportional to the arc length as shown in FIG. Vp is applied. During the base period Tb after time t2, a base current Ib less than the critical value is energized as shown in FIG. 6A, and a base voltage Vb that is substantially proportional to the arc length as shown in FIG. Is applied.

  When a magnetic blow occurs at time t21 and the arc is deflected, as shown in FIG. 5B, the arc length increases with the deflection of the arc, and the base voltage Vb gradually increases and increases. On the other hand, the base current Ib remains constant as shown in FIG. At time t3, when the deflection of the arc due to magnetic blowing is further increased, the arc length becomes so long that the arc cannot be maintained, and arc breakage occurs. When the arc break occurs, the welding current Iw stops flowing as shown in FIG. 5A, and the welding voltage Vw becomes a no-load voltage that is the maximum output voltage as shown in FIG.

  FIG. 7 is a current / voltage waveform diagram showing magnetic blow countermeasure control for preventing arc break caused by magnetic blow disclosed in Patent Document 1. FIG. 4A shows the time change of the welding current Iw, and FIG. 4B shows the time change of the welding voltage Vw. In the figure, a stable welding state in which magnetic blowing is not generated is shown during the pulse period from time t1 to t3, and a welding state in which magnetic blowing is generated during the subsequent pulse period from time t3 to t5. Show.

  During the pulse period from the time t1 to the time t3, since the magnetic blowing is not generated, the welding state is stable. Since the operation during this period is the same as that in FIG. 4 described above, a description thereof will be omitted.

  During the peak period Tp from time t3 to t4, the peak current Ip is energized as shown in FIG. 9A, and the peak voltage Vp is applied as shown in FIG. The base period Tb starts from time t4, the base current Ib is energized as shown in FIG. 5A, and the normal base voltage Vb is applied as shown in FIG. At time t41 in the base period Tb, the arc length is increased because the magnetic blow is generated and the arc is deflected, and the base voltage Vb is increased and increased as shown in FIG. At time t42, the value of the base voltage Vb becomes equal to or higher than a predetermined reference voltage value Vt indicated by a broken line. When it is determined that the base voltage value Vb is equal to or higher than the reference voltage value Vt, the base current Ib is increased from the normal value to 200 A or higher as shown in FIG. During the period from time t42 to t43, the base voltage value Vb is equal to or higher than the reference voltage value Vt. During this period, the base current increased to 200 A or more is applied as shown in FIG.

  During the period from time t42 to t43, since the value of the base current Ib increases to 200 A or more, since the rigidity that is a property that the arc is generated in the wire feeding direction becomes strong, the deflection of the arc is in a normal state. Will be returned. For this reason, as shown in FIG. 5B, at time t43, the base voltage value Vb becomes less than the reference voltage value Vt, and then rapidly decreases and returns to the normal value. Therefore, the magnetic blow occurs at time t41 and is canceled immediately after time t43. At time t43, the value of the base current Ib returns to the normal value as shown in FIG. During the remaining base period Tb from time t43 to t5, the value of the base current Ib remains the normal value as shown in FIG. 5A, and the base value of the normal value is maintained as shown in FIG. A voltage value Vb is applied. The arc during this period is in a stable state because no magnetic blow has occurred.

  In the above, the reference voltage value Vt is set to an appropriate value according to the welding conditions in consideration of the fluctuation of the base voltage value Vb in a state where no magnetic blow is generated. For example, since the fluctuation of the base voltage Vb does not reach the peak voltage value Vp, the reference voltage value Vt is set to a value close to the peak voltage value Vp. In addition, hysteresis may be provided in comparison between the base voltage Vb and the reference voltage value Vt. That is, the reference value when the base voltage Vb increases from the normal value is the first reference voltage value Vt1, and the reference value when the base voltage Vb once exceeds Vt1 and then decreases is the second reference voltage value Vt2. It is what. At this time, Vt1> Vt2. Further, the occurrence of magnetic blow is determined when the increase rate of the base voltage Vb (differential value = dVw / dt) reaches the reference value, and then the magnetic blow rate is determined when the decrease rate of the base voltage Vb reaches the reference value. You may make it discriminate | determine cancellation | release. Various conventional methods for determining the occurrence of magnetic blow by increasing the base voltage Vb can be used. The increased base current value is experimentally set to a value that can correct the arc deflection in the range of about 200 to 500 A.

  By performing such magnetic blow countermeasure control, it is possible to prevent arc breakage due to magnetic blow.

JP 2004-268081 A

  In the above-described prior art, arc breakage can be prevented from occurring by discriminating arc deflection caused by magnetic blowing and increasing the base current to 200 A or more. In the pulse arc welding, as described above, a base current having a small current value is applied during the base period so that droplets are not formed at the tip of the welding wire. During the peak period, a peak current having a large current value is applied in order to form a droplet having the same diameter as the wire diameter and release it. If the base current is greatly increased as in the conventional magnetic blow countermeasure control, droplets are formed at that time, and the stable droplet transfer state is disturbed. As a result, the bead appearance of the portion where the base current is increased is affected. When the pulse cycle with the base current increased for the countermeasure against magnetic blowing continues for a short period, the influence on the bead appearance is limited. However, when welding a welded part where magnetic blow occurs violently, the pulse cycle in which the base current is increased continues continuously for a long period of time. In this case, arc breakage due to magnetic blowing can be suppressed to prevent the occurrence of welding defects, but the bead appearance is deteriorated.

  Therefore, an object of the present invention is to provide an arc welding control method capable of preventing arc breakage due to magnetic blowing and suppressing deterioration of the bead appearance.

In order to solve the above-described problems, the invention of claim 1
In an arc welding control method of welding by pulsed arc welding that feeds a welding wire and energizes a welding current formed from a peak current during a peak period and a base current during a base period,
It has a test welding mode and a working welding mode,
When the test welding mode is selected, at the time of the test welding by the pulse arc welding , the welding voltage is increased during the base period, and a welding point where a magnetic blow has occurred is determined from a plurality of welding points. Automatically memorize the welding location
When the execution welding mode is selected, during welding, when welding locations other than the stored magnetic blow generation welding locations are welded by the pulse arc welding, the stored magnetic blow generation welding is performed. When welding locations, the welding method is automatically switched from pulse arc welding to DC arc welding, and welding is performed.
An arc welding control method characterized by the above.

In the invention of claim 2, the DC arc welding is short-circuit transfer welding.
The arc welding control method according to claim 1, wherein:

According to the present invention, test welding is performed by pulse arc welding in which a welding portion where a magnetic blow has occurred is determined and stored from among a plurality of welding locations due to an increase in welding voltage during the base period. When welding welds other than the welded locations where magnetic blow is generated, welding is performed by pulse arc welding. When welding stored locations where magnetic blow is generated, the welding method is switched from pulse arc welding to DC arc welding. I do. For this reason, it is possible to suppress arc breakage due to magnetic blowing without increasing the base current, and thus it is possible to maintain a good bead appearance.

It is the figure which showed the welding line of three welding locations as three straight lines, in order to demonstrate the arc welding control method which concerns on embodiment of this invention. In embodiment of this invention, it is an electric current and a voltage waveform figure when welding the magnetic blow generation | occurrence | production generation | occurrence | production welding part by DC arc welding. It is a block diagram of the welding apparatus for enforcing the arc welding control method concerning an embodiment of the invention. It is a current and voltage waveform diagram of pulse arc welding in the prior art. It is a figure which shows an arc state when magnetic blowing generate | occur | produces in a prior art. FIG. 6 is a current / voltage waveform diagram when magnetic blow occurs in pulse arc welding of the prior art. It is a current / voltage waveform diagram showing magnetic blow countermeasure control for preventing arc breakage due to magnetic blow in the prior art.

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

FIG. 1 is a diagram showing three welding lines as three straight lines for explaining the arc welding control method according to the embodiment of the present invention. In the drawing, Ps1 indicates the first welding start position of the first welding point, and Pe1 indicates the first welding end position. Similarly, Ps2 indicates the second welding start position of the second welding point, and Pe2 indicates the second welding end position. Similarly, Ps3 indicates the third welding start position of the third welding point, and Pe3 indicates the third welding end position. These first to third welding locations are arc welded using a robot. Arc welding is divided into test welding and execution welding.

(1) Test welding Three weldings are sequentially performed from the first welding point to the third welding point by pulse arc welding to which the magnetic blow countermeasure control described above with reference to FIG. 7 is added. When the occurrence of magnetic blow is determined during welding, the welding location is stored. In the figure, it is assumed that the occurrence of magnetic blow is determined while welding the second welding point. This second welding location will be referred to as a magnetic blow generating welding location. Therefore, in the same figure, no magnetic blow occurred at the first weld location, no magnetic blow occurred at the second weld location, and no magnetic blow occurred at the third weld location. That is, in the test welding, an operation of discriminating and storing a welding portion where magnetic blowing has occurred from a plurality of welding locations. As described above, the determination of the occurrence of magnetic blow can be made by the fact that the base voltage has risen above the reference voltage value. It can also be performed when the base voltage increase rate is equal to or higher than the reference increase rate. When the magnetic blow is determined, as described above, the base current is increased to prevent arc interruption. Since it is test welding, the base current may not be increased. The magnetic blow generating welded portion can be identified by the fact that the pulse period for determining the occurrence of magnetic blow exists more than the reference number during the welding period of the welded portion. The reference number is set to an appropriate value by experiment within a range of about 1 to 50 times. Also, the magnetic blow generation welding location is determined by the ratio of the number of pulse cycles that determined the occurrence of magnetic blow in the total number of pulse cycles during the welding period of the weld location being greater than or equal to the reference ratio. You can also The reference ratio is set to an appropriate value by experiment within a range of about 5 to 20%. Moreover, in the same figure, although the magnetic blow generation | occurrence | production welding location is one, there may be a plurality of magnetic blow generation weld locations.

(2) Practical Welding During the practicing work, since the first welding location is not a magnetic blow generating welding location, welding is performed by the pulse arc welding described above with reference to FIG. Since the second welding location is a magnetic blow generating welding location, the welding method is switched from pulse arc welding to DC arc welding, and welding is performed. Here, DC arc welding is normal MAG welding in which the welding current is not a pulse waveform but a DC waveform. DC arc welding is short-circuit transfer welding when the average welding current value is less than the critical value, and spray transfer welding when the average value is higher. The reason why arc break due to magnetic blowing can be prevented when the welding method is DC arc welding will be described later with reference to FIG. At the third welding location, the welding method is switched again to pulse arc welding, and welding is performed. Therefore, the welding method is pulse arc welding at the first welding point, DC arc welding at the magnetic blow generating welding point, which is the second welding point, and pulse arc welding at the third welding point. DC arc welding generates more spatter than pulse arc welding. However, rather than increasing the base current as in the prior art and making the bead appearance worse, a slight increase in spatter has less effect on the weld quality. The reason why the first welding point and the third welding point that are not the magnetic blow generating welding points are welded by pulse arc welding is to avoid the increase in spatter. In the present invention, unlike the prior art, the base current Ib is not increased after the arc deflection due to magnetic blowing has progressed to some extent, but by automatically switching the welding method to DC arc welding, the arc break due to magnetic blowing is prevented. It is preventing. For this reason, it can suppress that a bead external appearance worsens.

  FIG. 2 is a current / voltage waveform diagram when the above-described magnetic blow generating welds are welded by DC arc welding. FIG. 4A shows the time change of the welding current Iw, and FIG. 4B shows the time change of the welding voltage Vw. The figure shows the case where the DC arc welding is short-circuit transfer welding. Hereinafter, a description will be given with reference to FIG.

  During the short-circuit period from time t1 to t2, the welding wire and the base material are in a short-circuit state, and the welding voltage Vw is substantially 0 V as shown in FIG. The welding current Iw increases in a curved line. During the arc period from time t2 to time t3, an arc is generated between the welding wire and the base material, and as shown in FIG. 5B, the welding voltage Vw is about 20 to 30 V, and FIG. ), The welding current Iw decreases in a curved line. During the short-circuit period from time t3 to t4 and the arc period from time t4 to t5, the above operation is repeated and welding is performed.

  In DC arc welding, arc length control is performed to obtain good welding quality. For DC arc welding, a welding power source having a constant voltage characteristic is used. Therefore, in the arc length control of DC arc welding, the output of the welding power source is controlled so that the welding voltage average value becomes equal to a predetermined voltage setting value. In short-circuit transfer welding, the tip of the welding wire melts to form droplets during the arc period, and the droplets move to the base material (molten pool) during the short-circuit period. In order to stabilize this droplet transfer state, the increasing waveform of the welding current Iw during the short-circuit period is controlled. If the droplet transfer state is stabilized, the bead appearance is improved and the amount of spatter generated is reduced. However, it is not as small as the amount of spatter generated by pulse arc welding. In spray transfer welding, almost no short circuit occurs, and the droplets are transferred by free fall without short circuit by spray transfer.

  In direct current arc welding, welding is performed in a state where the arc length is shorter than that of pulse arc welding, so that even if a force deviated from a magnetic field is applied, the arc is not easily deflected. For this reason, arc breakage due to magnetic blowing hardly occurs. Further, the reason why arc breakage due to magnetic blowing is less likely to occur in direct current arc welding is that there is almost no state in which a small current is applied like the base current of pulse arc welding, so the arc is difficult to deflect. Among direct current arc welding, short-circuit transfer welding is performed in a state where the arc length is shorter than spray transfer welding, so that arc breakage due to magnetic blowing is less likely to occur.

  A welding point that is not a magnetic blow generating welding point is welded by the pulse arc welding described above with reference to FIG. Since the current / voltage waveforms at this time are in a stable welding state in which no magnetic blowing occurs, they are waveforms during the period from time t1 to t3 in FIG. However, as a rare case, when magnetic blowing occurs, the waveform is from time t3 to t5.

  FIG. 3 is a block diagram of a welding apparatus for carrying out the arc welding control method according to the above-described embodiment of the present invention. The welding apparatus is mainly composed of a welding power source PS surrounded by a broken line, a robot control device RC, a robot (not shown), and the like. Hereinafter, each block will be described with reference to FIG.

  The welding power source PS is composed of the following blocks. However, a circuit for feeding control of the welding wire 1 is omitted. The power supply main circuit MC receives an AC commercial power supply (not shown) such as three-phase 200V as input, performs output control such as inverter control in accordance with a drive signal Dv described later, and generates a welding voltage Vw and welding current Iw suitable for welding. Output. Although not shown, this power supply main circuit MC is a primary rectifier circuit that rectifies an AC commercial power supply, a capacitor that smoothes the rectified direct current, an inverter circuit that converts the smoothed direct current into high-frequency alternating current according to the drive signal Dv, It comprises an inverter transformer that steps down the high-frequency alternating current to a voltage value suitable for welding, and a secondary rectifier circuit that rectifies the stepped-down high-frequency alternating current. Reactor WL is inserted between the + side output of power supply main circuit MC and welding torch 4 and smoothes the output of power supply main circuit MC. The welding wire 1 is fed through the welding torch 4 by the rotation of a feeding roll 5 of a wire feeder (not shown), and an arc 3 is generated between the welding wire 1 and the base material 2. The wire feeder and the welding torch 4 are mounted on the robot.

  The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The voltage averaging circuit VAV averages (passes through the low-pass filter) the voltage detection signal Vd and outputs a voltage average signal Vav. The voltage setting circuit VR outputs a voltage setting signal Vr having a desired value. The voltage error amplification circuit EV amplifies an error between the voltage setting signal Vr and the voltage average signal Vav, and outputs a voltage error amplification signal Ev. The V / F converter VF outputs a pulse period signal Tf which is a trigger signal that becomes a high level for a short time at a frequency corresponding to the voltage error amplification signal Ev. The pulse period signal Tf is a signal that determines a frequency having a peak period and a base period as one period. The peak period setting circuit TPR outputs a predetermined peak period setting signal Tpr. The peak period timer circuit TTP receives the peak period setting signal Tpr and the pulse period signal Tf as described above, and becomes High level only for a period determined by the peak period setting signal Tpr every time the pulse period signal Tf changes to High level for a short time. After that, the peak period signal Ttp that is low level is output until the pulse period signal Tf next becomes high level. Therefore, the peak period signal Ttp is a signal that is at a high level during the peak period and is at a low level during the base period.

  The magnetic blow occurrence determination circuit AD receives the voltage detection signal Vd and the peak period signal Ttp as an input, and the reference of the value of the voltage detection signal Vd when the peak period signal Ttp is at the low level (base period) is predetermined. Only when the voltage value is equal to or higher than the voltage value, the magnetic blow occurrence determination signal Ad that becomes a high level is output. In other words, this magnetic blow occurrence determination signal Ad is a signal that determines that the base voltage has risen due to the deflection of the arc caused by the magnetic blow and becomes a high level. As described above, the occurrence of the magnetic blow may be determined as a period in which the decrease rate becomes equal to or higher than the reference decrease rate after the increase rate of the base voltage becomes equal to or higher than the reference increase rate.

  The peak current setting circuit IPR outputs a predetermined peak current setting signal Ipr. The base current setting circuit IBR receives the above-described magnetic blow occurrence determination signal Ad and outputs a base current setting signal Ibr having a predetermined increased value when the magnetic blow occurrence determination signal Ad is at a high level, and when the magnetic blow occurrence determination signal Ad is at a low level. Outputs a base current setting signal Ibr having a predetermined normal value. The switching circuit SW outputs the peak current setting signal Ipr as the current switching setting signal Isw when the peak period signal Ttp is high level, and the base current setting signal Ibr when the peak period signal Ttp is low level. Output as signal Isw.

  The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The current error amplification circuit EI amplifies an error between the current switching setting signal Isw and the current detection signal Id, and outputs a current error amplification signal Ei. The external characteristic switching circuit SWC receives the voltage error amplification signal Ev, the current error amplification signal Ei, and the magnetic blow generation welding location signal Pd from the robot controller RC described later, and receives the magnetic blow generation welding location signal Pd. When the signal is at the high level, the voltage error amplification signal Ev is output as the error amplification signal Ea. When the signal is at the low level, the current error amplification signal Ei is output as the error amplification signal Ea. Therefore, when the magnetic blow generation welding location signal Pd is at a high level (magnetic blow generation weld location), constant voltage characteristics are obtained, and DC arc welding is performed, and when it is low levels, constant current characteristics are obtained and pulse arc welding is performed. become. The drive circuit DV receives the error amplification signal Ea and the activation signal On from the robot controller RC described later, and performs PWM modulation control based on the error amplification signal Ea when the activation signal On is at a high level. A drive signal Dv for driving the inverter circuit is output, and the drive signal Dv is not output when the activation signal On is at a low level.

The robot controller RC receives the magnetic blow occurrence determination signal Ad as described above, and the test welding mode or the execution welding mode is selected and performs the following operation in each mode, and the start signal On and the magnetic blow The generated welding location signal Pd is output.
1) In the test welding mode, the magnetic blow welding position signal Pd is output at a low level, and at the time when the welding torch is moved to the first welding start position Ps1 as described above with reference to FIG. Output as level. Thereafter, pulse arc welding is performed along the welding line in accordance with the work program. During this welding, when the magnetic blow occurrence determination signal Ad becomes High level, it is stored as a magnetic blow occurrence weld location. When the welding torch is moved to the first welding end position Pe1, the start signal On is set to the low level, and the welding at the first welding point is ended. The above operation is performed in the same manner for the second and third welding locations.
2) In the working welding mode, as described above with reference to FIG. 1, when the welding torch is moved to the first welding start position Ps1, the magnetic blow generation welding location signal Pd is set to the Low level and output, and the start signal Output On with High level. Thereafter, pulse arc welding is performed along the welding line in accordance with the work program. When the welding torch is moved to the first welding end position Pe1, the start signal On is set to the low level, and the welding at the first welding point is ended. Next, when the welding torch is moved to the second welding start position Ps2, the magnetic blow generation welding location signal Pd is output at a high level and the start signal On is output at a high level. Thereafter, DC arc welding is performed along the welding line according to the work program. When the welding torch is moved to the second welding end position Pe2, the start signal On is set to the Low level, and the welding at the second welding point is ended. Next, when the welding torch is moved to the third welding start position Ps3, the magnetic blow generation welding location signal Pd is output at the Low level, and the start signal On is output at the High level. Thereafter, pulse arc welding is performed along the welding line in accordance with the work program. When the welding torch is moved to the third welding end position Pe3, the start signal On is set to the Low level, and the welding at the third welding point is ended.

  In both cases of test welding and execution welding, when pulsed arc welding is performed, when the magnetic blow occurrence determination signal Ad becomes high level, the base current is increased to correct the deflection of the arc caused by the magnetic blow. . However, in the case of test welding, the base current may not be increased.

  According to the above-described embodiment, test welding is performed by pulsed arc welding in which a welding portion where a magnetic blow has occurred is identified and stored from among a plurality of welding locations due to an increase in welding voltage during the base period. Sometimes, welding is performed by pulse arc welding when welding locations other than the stored magnetic blow generating weld locations, and when welding the stored magnetic blow generating weld locations, the welding method is changed from pulse arc welding to DC arc welding. Switch to perform welding. For this reason, it is possible to suppress arc breakage due to magnetic blowing without increasing the base current, and thus it is possible to maintain a good bead appearance.

1 Welding wire
2 Base material
3 arc
4 Welding torch
5 Feeding roll
AD Magnetic blow occurrence detection circuit
Ad Magnetic blow occurrence determination signal
Dv drive signal
Ea Error amplification signal
EI current error amplifier circuit
Ei Current error amplification signal
EV voltage error amplifier circuit
Ev Voltage error amplification signal
Iav welding current average value
Ib Base current IBR Base current setting circuit
Ibr Base current setting signal
ID current detection circuit
Id Current detection signal
Ip peak current IPR peak current setting circuit
Ipr peak current setting signal
Isw current switching setting signal
Iw welding current
MC main circuit On start signal
Pd Magnetic blow generation welding location signal
Pe1 First welding end position
Pe2 Second welding end position
Pe3 Third welding end position
PS welding power source
Ps1 First welding start position
Ps2 Second welding start position
Ps3 Third welding start position
RC robot controller
SW switching circuit
SWC External characteristic switching circuit
Tb Base period Tf Pulse period (signal)
Tp Peak period TPR Peak period setting circuit
Tpr Peak period setting signal
TTP peak period timer circuit
Ttp peak period signal
VAV voltage averaging circuit
Vav welding voltage average value / voltage average signal
Vb Base voltage VD Voltage detection circuit
Vd Voltage detection signal
VF V / F converter
Vp peak voltage VR voltage setting circuit
Vr voltage setting signal
Vt reference voltage value Vt1 first reference voltage value
Vt2 Second reference voltage value
Vw welding voltage
WL reactor

Claims (2)

In an arc welding control method of welding by pulsed arc welding that feeds a welding wire and energizes a welding current formed from a peak current during a peak period and a base current during a base period,
It has a test welding mode and a working welding mode,
When the test welding mode is selected, at the time of the test welding by the pulse arc welding , the welding voltage is increased during the base period, and a welding point where a magnetic blow has occurred is determined from a plurality of welding points. Automatically memorize the welding location
When the execution welding mode is selected, during welding, when welding locations other than the stored magnetic blow generation welding locations are welded by the pulse arc welding, the stored magnetic blow generation welding is performed. When welding locations, the welding method is automatically switched from pulse arc welding to DC arc welding, and welding is performed.
An arc welding control method characterized by the above. The DC arc welding is short circuit transfer welding,
The arc welding control method according to claim 1.

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