KR20170037941A - Arc welding control method - Google Patents

Abstract

The welding speed Iw of the welding wire 1 is alternately switched between the forwarding period Tas and the backing period Tar and the welding current Iw is welded by repeating the short- The control method includes the steps of detecting a smooth value of the welding current Iw and feedback-controlling the waveform parameter of the feeding speed Fw so that the welding current smoothing value is equal to a predetermined current setting value, Even if the distance between the base materials varies, the welding current smoothed value can be kept constant, and the penetration depth can be made uniform.

Description

[0001] ARC WELDING CONTROL METHOD [0002]

The present invention relates to an arc welding control method in which the feeding speed of a welding wire is alternately switched between a forwarding period and a backing period, repeats a short-circuit period and an arc period, and welds the current with welding current.

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

In order to further improve the welding quality, there has been proposed a method in which the welding of the welding wire is repeated periodically and repeatedly. In the invention of Patent Document 1, the average value of feeding speed according to the welding current setting value, and the frequency and amplitude of the forward and backward feed of the welding wire are set to values according to the welding current setting value. In the welding method of repeating the forward and reverse feed of the welding wire, it is possible to set the repetition period of the short circuit and the arc to the desired value, which is impossible in the conventional technology of the constant speed feeding. Therefore, the welding quality such as the reduction of the amount of spatter generated and the improvement of the bead appearance Improvement can be achieved.

According to the invention of Patent Document 2, feed rate control is performed by feed-forwarding the welding wire so that the welding current and the predetermined current setting value become equal to each other. In normal consumable electrode arc welding, the feeding speed during welding is a constant value. On the other hand, according to the invention of Patent Document 2, the feeding speed is variably controlled so that the welding current value becomes constant even if the distance between the feeding chip and the base material is changed. The penetration depth of the base material is approximately proportional to the welding current value, so that if the welding current value becomes constant, the penetration depth becomes uniform. In ordinary arc welding, welding is performed while maintaining a constant distance between the power supply chip and the base material. However, in the case of deep improvement welding, multi-layer welding, etc., it may be difficult to keep the distance between the feed chip and the base material at a constant value due to the problem of interference between the welding torch and the base material. In the invention of Patent Document 2, in the welding in which the distance between the feed chip and the base material is varied as described above, the feeding speed is variably controlled and the welding current value is kept constant. Thus, fluctuation of the penetration depth, , And can be made uniform.

Japanese Patent No. 5201266 Japanese Patent Application Laid-Open No. 7-51854

It is an object of the present invention to provide an arc welding control method capable of uniformizing the penetration depth even when the distance between the feed chip and the base material varies in the welding for alternately switching the feeding period and the feeding period.

In order to solve the above-mentioned problems, the arc welding control method of the present invention includes:

An arc welding control method for alternately switching the feeding speed of a welding wire to a forwarding period and a backing period, repeating a short-circuit period and an arc period,

And the waveform parameter of the feeding speed is feedback-controlled so that the welding current smoothing value and the predetermined current setting value become equal to each other.

The arc welding control method of the present invention is characterized in that the waveform parameter is an amplitude and / or a forward shift amount.

The arc welding control method of the present invention is characterized in that the waveform parameter is at least one of a forwarding acceleration period, a forwarding deceleration period, a reverse acceleration period, a reverse deceleration period, a forwarding amplitude or a reverse amplification amplitude.

The arc welding control method of the present invention is characterized in that the feedback control is performed only when the current setting value is equal to or greater than a predetermined reference current value.

In the arc welding control method of the present invention, the feedback-controlled waveform parameter is changed in synchronization with a specific timing in the short-circuit period.

According to the present invention, even when the distance between the feeding chip and the base material is changed, the welding current smoothed value can be kept constant in the welding for alternately switching the forwarding period and the backing period of the feeding speed, so that the penetration depth can be made uniform .

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.
2 is a timing chart of each signal in the welding power supply of Fig. 1 showing the arc welding control method according to the first embodiment of the present invention.
3 is a timing chart of each signal in the welding power supply of Fig. 1 showing the operation of the feed rate variation control in the arc welding control method according to the first embodiment of the present invention.
4 is a block diagram of a welding power source for implementing an arc welding control method according to Embodiment 2 of the present invention.
5 is a block diagram of a welding power source for implementing an arc welding control method according to Embodiment 3 of the present invention.
Fig. 6 is a timing chart of each signal in the welding power supply of Fig. 5 showing the arc welding control method according to the third embodiment of the present invention. Fig.
7 is a block diagram of a welding power source for implementing an arc welding control method according to Embodiment 4 of the present invention.
8 is a timing chart of each signal in the welding power supply of Fig. 7 showing the arc welding control method according to the fourth embodiment of the present invention.
Fig. 9 is a timing chart of each signal in the welding power supply of Fig. 7 showing the operation of variable feed rate control in the arc welding control method according to the fourth embodiment of the present invention. Fig.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]

The invention of the first embodiment is to feedback-control the amplitude and / or the forward-side shift amount, which is a waveform parameter of the feeding speed, such that the smooth value of the welding current is equal to the predetermined current setting value.

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 main circuit PM receives a commercial power supply (not shown) such as three-phase 200V, and performs output control by inverter control or the like in accordance with a drive signal Dv to be described later to output an output voltage E. The power main circuit PM includes a primary rectifier for rectifying a commercial power source, a smoothing capacitor for smoothing the rectified direct current, an inverter circuit (not shown) driven by the drive signal Dv for converting a smoothed direct current into a high- A high frequency transformer for reducing the high frequency AC to a voltage suitable for welding, and a secondary rectifier for rectifying the coiled high frequency AC into direct current.

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

The feed motor WM receives the feed control signal Fc to be described later and feeds the welding wire 1 at the feed speed Fw by cyclically repeating the normal feed and the reverse feed. For the feed motor WM, a motor with a high transient response is used. The feeding motor WM may be provided in the vicinity of the tip of the welding torch 4 in order to speed up the rate of change of the feeding speed Fw of the welding wire 1 and the inversion of the feeding direction. There are also cases where two feeding motors WM are used and a push-pull type feeding system is used.

The welding wire 1 is fed into 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 feeding chip (not shown) and the base material 2 in the welding torch 4, and the welding current Iw is energized.

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 the output voltage detection signal Ed.

The voltage error amplifier circuit EA receives the output voltage setting signal Er and the output voltage detection signal Ed as described above and amplifies the error between the output voltage setting signal Er (+) and the output voltage detection signal Ed (-), And outputs the voltage error amplified signal Ea. With this circuit, the welding power source is controlled at a constant voltage.

The driving circuit DV receives the voltage error amplification signal Ea as described above, performs PWM modulation control based on the voltage error amplification signal Ea, and outputs a driving signal Dv for driving the inverter circuit in the power main circuit PM .

The current detection circuit ID detects the welding current Iw and outputs the current detection signal Id. The current smoothing circuit IAV receives the current detection signal Id as input, and outputs a smoothed current signal Iav. This smoothing is performed by using a smoothing circuit composed of a resistor and a capacitor, a low-pass filter, and the like. When a low-pass filter is used, the time constant of smoothing can be performed by setting a cutoff frequency (about 1 to 10 Hz).

The current setting circuit IR outputs a predetermined current setting signal Ir that becomes the target current value in the feed rate variation control. The feed error amplifying circuit EF amplifies the error between the current setting signal Ir (+) and the welding current smoothing signal Iav (-) to output the feed error amplifying signal Ef.

The period setting circuit TFR outputs a predetermined period setting signal Tfr.

The amplitude setting circuit WFR receives the feed error amplification signal Ef as described above, integrates the feed error amplification signal Ef during welding, and outputs the amplitude setting signal Wfr. The integral can be expressed as Wfr = Wf0 +? Ef? Dt. Here, Wf0 is a predetermined initial value. With this circuit, the value of the amplitude setting signal Wfr is feedback-controlled so that the value of the welding current smoothing signal Iav becomes equal to the value of the current setting signal Ir, and is varied instantaneously during welding.

The forward shift amount setting circuit SFR inputs the feed error amplification signal Ef as described above, integrates the feed error amplified signal Ef during welding, and outputs the forward shift amount setting signal Sfr. The integral can be expressed as Sfr = Sf0 +? Ef? Dt. Here, Sf0 is a predetermined initial value. With this circuit, the value of the forward-side shift amount setting signal Sfr is feedback-controlled so that the value of the welding current smoothing signal Iav becomes equal to the value of the current setting signal Ir, and is varied instantaneously during welding.

The feed rate setting circuit FR is supplied with the period setting signal Tfr, the amplitude setting signal Wfr, and the forward shift amount setting signal Sfr described above, and supplies the cycle setting signal Tfr and the amplitude setting signal Wfr As a feeding speed setting signal Fr, a feeding speed pattern obtained by shifting the sine wave formed from the amplitude determined by the forward-side shift amount setting signal Sfr by the forward-side shift amount. When the feeding speed setting signal Fr is 0 or more, it is a forwarding period. When it is less than 0, it is a backing period.

The feeding control circuit FC inputs the feeding speed control signal Fc for feeding the welding wire 1 at the feeding speed Fw corresponding to the value of the feeding speed setting signal Fr, WM.

2 is a timing chart of each signal in the welding power supply of Fig. 1 showing the arc welding control method according to the first embodiment of the present invention. 2 (A) shows the time variation of the feeding speed Fw, FIG. 2 (B) shows the time variation of the welding current Iw, and FIG. 2 (C) shows the time variation of the welding voltage Vw. Hereinafter, this will be described with reference to FIG.

As shown in Fig. 2 (A), the feeding speed Fw is a forwarding period higher than 0, and a lower feeding period Fw is a backing period. The forwarding means feeding the welding wire in the direction of approaching the base material, and the reverse feeding means feeding the welding wire in the direction away from the base material. The feeding speed Fw changes in a sinusoidal wave form, and has a waveform shifted to the forward side. Therefore, the average value of the feeding speed Fw is a positive value, and the welding wire is forwarded on average. The feeding speed pattern of the feeding speed Fw may be a triangular wave, a trapezoidal wave, or the like.

As shown in Fig. 2A, the feeding speed Fw is 0 at the time t1, the forwarding acceleration period during the period from the time t1 to t2, the maximum value of the forwarding at the time t2, The time period from t3 to t4 is the backward acceleration period, the time period from the time t4 is the backward movement maximum value, and the period from time t4 to t5 is the backward deceleration period . Then, the period from time t5 to t6 is again the forwarding acceleration period, and the period from time t6 to t7 is again the forwarding deceleration period. Therefore, the feeding speed Fw is the amplitude Wf (m / min) and the forward shift amount Sf (m / min) which are the difference between the cycle Tf (ms) from time t1 to t5, the maximum value of forwarding at time t2, ) In the feed rate pattern. Here, the period Tf is set to a predetermined value by the period setting circuit TFR in Fig. The amplitude Wf is feedback-controlled by the feed error amplifier circuit EF and the amplitude setting circuit WFR of Fig. 1 so that the value of the welding current smoothing signal Iav becomes equal to the value of the current setting signal Ir. The forward shift amount Sf is feedback-controlled by the feed error amplifier circuit EF and the forward shift amount setting circuit SFR in Fig. 1 so that the value of the welding current smoothing signal Iav becomes equal to the value of the current setting signal Ir. The cycle Tf is set to about 8 to 20 ms, the amplitude Wf is changed in the range of about 30 to 100 m / min, and the forward shift amount Sf is changed in the range of about 3 to 20 m / min.

The short-circuit between the welding wire and the base material often occurs before and after the forward maximum value at time t2. In Fig. 2, this occurs at time t21 in the forwarding deceleration period after the forwarding maximum value. When a short circuit occurs at time t21, as shown in Fig. 2C, the welding voltage Vw rapidly decreases to a short-circuit voltage value of several V, and as shown in Fig. 2B, the welding current Iw Is gradually increasing.

As shown in Fig. 2A, the feeding speed Fw is a backwash period from time t3, so that the welding wire is fed back. The short circuit is released by the backward movement, and the arc is generated again at time t31. The recurrence of the arc often occurs before and after the maximum value of the backlash at time t4. In Fig. 2, this occurs at the time t31 during the backward acceleration period before the backward shift maximum value. Therefore, the period from time t21 to t31 becomes the short-circuit period.

When the arc is reproduced at time t31, as shown in Fig. 2 (C), the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts. As shown in Fig. 2 (B), the welding current Iw starts changing from the state of the maximum value in the short-circuit period.

During the period from time t31 to time t5, as shown in Fig. 2A, the feeding speed Fw is in the reverse-feeding state, so that the welding wire is pulled up and the arc length becomes gradually longer. When the arc length becomes longer, the welding voltage Vw becomes larger and the constant voltage control is performed by the voltage error amplifying circuit EA of Fig. 1, so that the welding current Iw becomes smaller. Therefore, the arc period back-period Tar The welding voltage Vw gradually increases as shown in FIG. 2 (C), and the welding current Iw gradually decreases as shown in FIG. 2 (B).

Then, the next paragraph occurs at time t61 during the forward deceleration period from time t6 to time t7. However, the time (phase) from the forward maximum value is delayed from the short circuit occurring at time t61 as compared with the short circuit occurring at time t21. The timing at which the short circuit occurs has some degree of variation. The period from time t31 to time t61 becomes the arc period. During the period from time t5 to time t61, as shown in Fig. 2A, the feeding speed Fw is in the forwarding state, so that the welding wire is forwarded and the arc length is gradually shortened. When the arc length becomes short, the welding voltage Vw becomes small and the constant voltage is controlled by the voltage error amplifying circuit EA of FIG. 1, so that the welding current Iw becomes large. Therefore, the arc period transmission period Tas from time t5 to t61 , The welding voltage Vw gradually decreases as shown in FIG. 2 (C), and the welding current Iw gradually increases as shown in FIG. 2 (B).

3 is a timing chart of each signal in the welding power supply of Fig. 1 showing the operation of the feed rate variation control in the arc welding control method according to the first embodiment of the present invention. Fig. 3 (A) shows the time variation of the distance Lw between the feed chip and the parent material, Fig. 3 (B) shows the time variation of feed rate average value Fav, Fig. 3 (D) shows the time variation of the amplitude setting signal Wfr, and Fig. 3 (E) shows the time variation of the forward shift amount setting signal Sfr . Fig. 3 shows the transient response of each signal when the distance Lw between the feeding chip and the base material during welding is prolonged from L1 (mm) to L2 (mm) at time t1. The feed rate average value Fav represents an average value of the feed rate Fw shown in FIG. 2 (A) every one cycle. The time scale of FIG. 3 is 5 to 10 times longer than that of FIG. This will be described below with reference to FIG.

During the period before time t1, as shown in Fig. 3A, since the distance Lw between the power supply chip and the parent material is in a constant state of L1 (mm), the welding current shown by the solid line in Fig. The value of the smoothing signal Iav is in the same state as the value of the current setting signal Ir indicated by the broken line. Therefore, the amplitude setting signal Wfr shown in Fig. 3 (D) and the forward shift amount setting signal Sfr shown in Fig. 3 (E) are constant values, As described above, the feed rate average value Fav is in a substantially constant state.

When the distance between the welding torch and the parent material becomes long at time t1, the distance Lw between the power supply chip and the parent material becomes longer from L1 to L2 as shown in Fig. 3 (A). 3C, the value of the welding current smoothing signal Iav decreases with a slope from the time t1, and the value of the current setting signal Ir and the error (the feeding error amplification signal Ef > 0) Lt; / RTI > The amplitude of the welding current smoothing signal Iav is maintained at a constant value by varying the feeding speed variable control for returning the error to zero. The amplitude setting signal Wfr shown in FIG. 3 (D) and the amplitude setting signal Wfr shown in FIG. Both the values of the forward shift amount setting signal Sfr shown in the drawing become larger with a slope starting from the time t1. In response to this, as shown in Fig. 3 (B), the feed rate average value Fav is tilted from the time t1 and accelerated.

The value of the welding current smoothing signal Iav is decreased from time t1 as shown in Fig. 3 (C), reversed from decrease to increase at time t2, returned to the value before time t1 at time t3 The error with the current setting signal Ir becomes substantially zero. Both the amplitude setting signal Wfr shown in FIG. 3 (D) and the forward shift amount setting signal Sfr shown in FIG. 3 (E) gradually increase from time t1, and the value before time t1 Converges to a larger value than the above. In response to this, as shown in Fig. 3B, the feed rate average value Fav gradually increases from time t1 and converges to a value higher than the value before time t1 at time t3.

When the distance Lw between the feeding chip and the base material is changed in the direction of shortening, the value of the welding current smoothing signal Iav is once returned to its original value after being increased. Both the amplitude setting signal Wfr and the forward shift amount setting signal Sfr converge to values smaller than the value before the change and the feed rate average value Fav converges to a value lower than the value before the change. The transient period of time t1 to t3 is about 50 to 100 ms.

According to the first embodiment described above, the smoothing value of the welding current is detected, and the amplitude of the feeding speed and / or the shift amount of the forwarding side is feedback-controlled so that the welding current smoothing value and the predetermined current setting value are the same. Thus, in the present embodiment, the welding current smoothness value can be kept constant even when the distance between the feed chip and the base material is varied in the welding for alternately switching the feeding period and the feeding period. Therefore, can do. At this time, it is preferable to feedback-control both the amplitude of the feed speed and the forward shift amount. This is because the stability of the welding state is improved as compared with the case where only one side is feedback-controlled.

[Embodiment 2]

The invention of the second embodiment is for performing feedback control (feed rate variable control) only when the current set value is equal to or greater than a predetermined reference current value.

4 is a block diagram of a welding power source for implementing an arc welding control method according to Embodiment 2 of the present invention. Fig. 4 corresponds to Fig. 1 described above, and the same reference numerals are assigned to the same blocks, and description thereof is not repeated. FIG. 4 is a diagram in which the feed error amplifier circuit EF of FIG. 1 is replaced with a second feed error amplifier circuit EF2. Hereinafter, this block will be described with reference to FIG.

When the value of the current setting signal Ir is equal to or larger than the predetermined reference current value, the second feed error amplifying circuit EF2 receives the current setting signal Ir. The error of the current setting signal Ir (+) and the welding current smoothed signal Iav Amplifies the feed error amplified signal Ef and outputs the feed error amplified signal Ef which becomes 0 when the value of the current setting signal Ir is less than the reference current value. Thus, only when the value of the current setting signal Ir is equal to or larger than the reference current value, the feedback control of the amplitude setting signal Wfr and the forward shift amount setting signal Sfr is performed. The reference current value is set to about 200A.

According to the second embodiment, the feedback control (feeding speed variable control) is performed only when the current setting value (current setting signal Ir) is equal to or greater than a predetermined reference current value. When the current setting value is less than the reference current value, the welding state becomes unstable if the feeding speed variable control is performed. Therefore, the feeding speed variable control is prohibited. Further, when the current setting value is less than the reference current value, welding is performed so as not to fluctuate because the welding state becomes unstable when the distance between the feeding chip and the base material is changed.

[Embodiment 3]

The invention of the third embodiment is such that the amplitude of the feedback control and / or the forward shift amount changes in synchronization with the specific timing in the short-circuit period. In the first embodiment, the cycle of the feed speed and / or the shift amount of the forward feed side are varied asynchronously at an arbitrary timing of feed speed by feedback control. On the other hand, in Embodiment 3, the period and / or the forward shift amount is changed in synchronization with the specific timing in the short-circuit period, and is not changed at the other timing.

5 is a block diagram of a welding power source for implementing an arc welding control method according to Embodiment 3 of the present invention. Fig. 5 corresponds to Fig. 1 described above, and the same reference numerals are assigned to the same blocks, and description thereof will not be repeated. Fig. 5 is a diagram in which the voltage detection circuit VD and the short circuit determination circuit SD are added to Fig. 1, and the feed rate setting circuit FR of Fig. 1 is replaced with a second feed rate setting circuit FR2. Hereinafter, these blocks will be described with reference to FIG.

The voltage detection circuit VD detects the welding voltage Vw and outputs the voltage detection signal Vd. The short circuit determination circuit SD receives the voltage detection signal Vd as described above. When the value is less than a predetermined short circuit determination value (about 10 V), it is determined that the circuit is in the short circuit period and becomes High level. And outputs a short discrimination signal Sd which becomes a low level.

The second feeding speed setting circuit FR2 receives the short discrimination signal Sd, the period setting signal Tfr, the amplitude setting signal Wfr, and the forward shift amount setting signal Sfr, and outputs the period setting signal Tfr, the amplitude The values of the setting signal Wfr and the forward shift amount setting signal Sfr are read in synchronization with the timing at which the short discrimination signal Sd is changed to the high level (short circuit), and the period and amplitude setting signal Wfr determined by the period setting signal Tfr As a feeding speed setting signal Fr, a feeding speed pattern obtained by shifting the sine wave formed from the amplitude determined by the forward-side shift amount setting signal Sfr by the forward-side shift amount. That is, each waveform parameter of the feed rate setting signal Fr is updated in synchronization with the specific timing in the short-circuit period. The specific timing is a timing at which a short circuit occurs, a timing after a predetermined period since the occurrence of a short circuit, a timing at which the feed speed setting signal Fr changes from forward to backward during a short period, and the like.

Fig. 6 is a timing chart of each signal in the welding power supply of Fig. 5 showing the arc welding control method according to the third embodiment of the present invention. Fig. 6 (A) shows the time variation of the feeding speed Fw, FIG. 6 (B) shows the time variation of the welding current Iw, and FIG. 6 (C) shows the time variation of the welding voltage Vw. Fig. 6 corresponds to Fig. 2 described above, and description of the same operation is not repeated. Hereinafter, different operations will be described with reference to FIG.

When a short-circuit occurs at time t21, the values of the period setting signal Tfr, the amplitude setting signal Wfr, and the forward-side shift amount setting signal Sfr are read out in synchronization with the short-circuit occurrence timing by the second feeding speed setting circuit FR2 of Fig. And is updated. At this time, since the period setting signal Tfr is a predetermined value, it does not change. Since the values of the amplitude setting signal Wfr and the forward shift amount setting signal Sfr have changed in accordance with the feedback control, at time t21, as shown in Fig. 6A, the amplitude Wf of the feeding speed Fw, The amount Sf is large. The same is true at time t61 when the next paragraph occurs. As described above, the amplitude Wf and the forward shift amount Sf change in synchronization with the short circuit occurrence timing. As described above, the synchronization timing is a specific timing during the short-circuit period, and includes a short-circuit occurrence timing, a timing after a predetermined period from the occurrence of the short-circuit, and a timing (time t3) that changes from forward to reverse during a short-

The reason why the amplitude Wf and the forward shift amount Sf of the feed speed Fw are changed during the short-circuit period is that the welding state becomes unstable when the waveform of the feed speed Fw suddenly changes during the arc period. This is because, even if the feed speed Fw suddenly changes during the short-circuit period, the influence on the welding condition is small.

In the arc welding control method according to Embodiment 3 of the present invention, the timing chart of each signal in the welding power supply of Fig. 5 showing the operation of the feed rate variation control is the same as that of Fig. 3 described above, I never do that. The third embodiment is based on the first embodiment, but the second embodiment is also applicable to the second embodiment.

According to the third embodiment, the amplitude and / or the forward shift amount is changed in synchronization with the specific timing in the short-circuit period. Thus, in the present embodiment, since the waveform parameters of the feeding speed are updated during the short-circuit period, the welding condition can be stably maintained.

In Embodiments 1 to 3 described above, the case where both of the amplitude and the forward shift amount are changed by the feedback control has been described, but only one of them may be changed. The value of the parameter that is not changed is set to a predetermined value.

[Embodiment 4]

The invention of the fourth embodiment is characterized in that the waveforms of the feeding speed, the forwarding acceleration period, the forwarding deceleration period, the reverse acceleration period, the reverse deceleration period, the forwarding amplitude or the reverse amplification amplitude At least one of them is feedback-controlled. Then, the waveform parameter being feedback-controlled changes in synchronization with a specific timing in the short-circuit period.

7 is a block diagram of a welding power source for implementing an arc welding control method according to Embodiment 4 of the present invention. Fig. 7 corresponds to Fig. 5 described above, and the same reference numerals are assigned to the same blocks, and description thereof will not be repeated. 7 removes the period setting circuit TFR, the amplitude setting circuit WFR, and the forward shift amount setting circuit SFR shown in Fig. The second feeding error amplifier circuit EF2, which is the same as that of FIG. 4, is added, and a forwarding acceleration period setting circuit TSUR, a forwarding deceleration period setting circuit TSDR, a reverse feeding acceleration period setting circuit TRUR, a reverse feeding deceleration period setting circuit TRDR, , And a trailing-edge amplitude setting circuit WRR. In addition, the second feeding speed setting circuit FR2 of Fig. 5 is replaced by a third feeding speed setting circuit FR3. Hereinafter, these blocks will be described with reference to FIG.

When the value of the current setting signal Ir is equal to or larger than the predetermined reference current value, the second feed error amplifying circuit EF2 receives the current setting signal Ir. The error of the current setting signal Ir (+) and the welding current smoothed signal Iav Amplifies the feed error amplified signal Ef and outputs the feed error amplified signal Ef which becomes 0 when the value of the current setting signal Ir is less than the reference current value. Thereby, the feedback control is performed only when the value of the current setting signal Ir is equal to or larger than the reference current value. The reference current value is set to about 200A.

The transmission acceleration period setting circuit TSUR receives the above-mentioned feed error amplification signal Ef, integrates the feed error amplification signal Ef during welding, and outputs the transmission acceleration period setting signal Tsur. The integral can be expressed as Tsur = Tsu0 +? Ef? Dt. Here, Tsu0 is a predetermined initial value. With this circuit, the value of the forwarding acceleration period setting signal Tsur is feedback-controlled so that the value of the welding current smoothing signal Iav becomes equal to the value of the current setting signal Ir, and is varied instantaneously during welding.

The forwarding deceleration period setting circuit TSDR outputs a predetermined forwarding deceleration period setting signal Tsdr.

The trailing acceleration period setting circuit TRUR outputs a predetermined trailing acceleration period setting signal Trur.

The traction deceleration period setting circuit TRDR receives the feed error amplification signal Ef as described above, integrates the feed error amplification signal Ef during welding, and outputs a traverse deceleration period setting signal Trdr. The integral can be expressed as Trdr = Trd0 -? Ef? Dt. Here, Trd0 is a predetermined initial value. With this circuit, the value of the traverse deceleration period setting signal Trdr is feedback-controlled so that the value of the welding current smoothing signal Iav becomes equal to the value of the current setting signal Ir, and is varied instantaneously during welding.

The forwarding amplitude setting circuit WSR outputs a predetermined forwarding amplitude setting signal Wsr. The trapezial amplitude setting circuit WRR outputs a predetermined traverse amplitude setting signal Wrr.

The third feed rate setting circuit FR3 sets the feed forward acceleration period setting signal Tsur, the forward feed deceleration period setting signal Tsdr, the back feed acceleration period setting signal Trur, the feed forward deceleration period setting signal Trdr, The signal Wsr, the above-mentioned trapezoidal amplitude setting signal Wrr, and the above short-circuiting discrimination signal Sd, and outputs the feed rate pattern generated by the following processing as the feed rate setting signal Fr. When the feeding speed setting signal Fr is 0 or more, it is a forwarding period. When it is less than 0, it is a backing period. Further, the waveform parameters (Tsur, Tsdr, Trur, Trdr, Wsr, and Wrr) of the feeding speed are updated in synchronization with the specific timing in the short-circuit period. The specific timing is a timing at which a short circuit occurs, a timing after a predetermined period since the occurrence of a short circuit, a timing at which the feed speed setting signal Fr changes from forward to backward during a short period, and the like.

1) During the forwarding acceleration period Tsu determined by the forwarding acceleration period setting signal Tsur, a feed forward speed setting signal Fr that linearly accelerates from zero to the forwarding peak value Wsp of the positive value determined by the forwarding amplitude setting signal Wsr is output.

2) Subsequently, during the forward peak period Tsp, the feed forward speed setting signal Fr for holding the forward forward peak value Wsp is output.

3) When the short discrimination signal Sd changes from the low level (arc period) to the high level (short period), the waveform parameter of the feeding speed is read and updated. At the same time, it shifts to the forwarding deceleration period Tsd determined by the forwarding deceleration period setting signal Tsdr, and outputs a feeding speed setting signal Fr that decelerates from the forwarding peak value Wsp to zero on a straight line.

4) Subsequently, during the traverse acceleration period Tru determined by the traverse acceleration period setting signal Trur, the feed rate setting signal Fr that linearly accelerates from zero to the reverse peak value Wrp of the negative value determined by the traverse feed amplitude setting signal Wrr is set to Output.

5) Subsequently, during the reverse-rotation peak period Trp, the feed-forward speed setting signal Fr for holding the reverse-rotation peak value Wrp is output.

6) If the short discrimination signal Sd changes from the high level (short-circuit period) to the low level (arc period), it shifts to the trapezoidal deceleration period Trd determined by the trapezoidal deceleration period setting signal Trdr, And outputs a feed-rate setting signal Fr for decelerating the feed rate to a straight line.

7) By repeating the above steps 1) to 6), the feeding speed setting signal Fr of the feeding pattern changing to the trapezoidal wave of the government is generated.

8 is a timing chart of each signal in the welding power supply of Fig. 7 showing the arc welding control method according to the fourth embodiment of the present invention. 8A shows the time variation of feed rate Fw, FIG. 8B shows the time variation of the welding current Iw, FIG. 8C shows the time variation of the welding voltage Vw, (D) shows the change of the short detection signal Sd with time. Hereinafter, the operation of each signal will be described with reference to Fig.

The feeding speed Fw shown in FIG. 8 (A) is controlled to the value of the feeding speed setting signal Fr outputted from the third feeding speed setting circuit FR3 in FIG. The feeding speed Fw is a forwarding acceleration period Tsu that is feedback-controlled by the forwarding acceleration period setting signal Tsur of Fig. 7, a forwarding peak period Tsp that continues until a short occurs, a forward deceleration period Tsdr determined by the forwarding deceleration period setting signal Tsdr of Fig. A reverse traverse acceleration period Tru determined by the traverse acceleration period setting signal Trur of Fig. 7, a reverse traction peak period Trp continuing until an arc occurs, and a reverse deceleration period Trd . Further, the forwarding peak value Wsp is determined by the forwarding amplitude setting signal Wsr in Fig. 7, and the reverse-traveling peak value Wrp is determined by the backwarding amplitude setting signal Wrr in Fig. As a result, the feeding speed setting signal Fr becomes a feeding pattern that changes to a trapezoidal wave of the government. Feedback control of the waveform parameter of the feeding speed Fw is performed only when the value of the current setting signal Ir is equal to or greater than the reference current value, as in the second embodiment. Further, the waveform parameter of the feeding speed Fw to be feedback-controlled is changed in synchronization with the specific timing of the short-circuit period.

[Operation of reverse period of time t1 to t4]

As shown in Fig. 8 (A), the feeding speed Fw enters a predetermined traverse acceleration period Tru from time t1 to time t2 and is accelerated from 0 to the above-mentioned reverse-rotation peak value Wrp. During this period, the paragraph period continues.

When the traverse acceleration period Tru ends at time t2, as shown in Fig. 8 (A), the feed rate Fw enters the backward-wave peak period Trp and becomes the backward-wave peak value Wrp. Even during this period, the paragraph period continues.

When an arc occurs at time t3, as shown in Fig. 8 (D), the short discrimination signal Sd changes to Low level (arc period). In response to this, the routine proceeds to the predetermined traverse deceleration period Trd from time t3 to time t4, and as shown in Fig. 8 (A), the feed rate Fw is decelerated from zero to the zero point. At the same time, as shown in Fig. 8C, the welding voltage Vw rapidly increases to an arc voltage value of several tens V, and the welding current Iw gradually decreases during the arc period as shown in Fig. 8B .

[Operation during forwarding period from time t4 to t7]

When the backlash deceleration period Trd is finished at time t4, the process shifts to the predetermined forwarding acceleration period Tsu from time t4 to t5. During this transmission acceleration period Tsu, as shown in Fig. 8 (A), the feeding speed Fw is accelerated from 0 to the forwarding peak value Wsp. During this period, the arc period continues.

When the forwarding acceleration period Tsu ends at time t5, as shown in Fig. 8 (A), the feeding speed Fw enters the forwarding peak period Tsp and becomes the forwarding peak value Wsp. The arc period continues during this period.

When a short circuit occurs at time t6, as shown in Fig. 8D, the short-circuiting determination signal Sd is changed to the high level (short-circuit period) and the forwarding acceleration period setting signal Tsur and the back- The setting signal Trdr is read and updated in synchronization with the occurrence of the short circuit. In response to this, the routine proceeds to the predetermined constant-speed deceleration period Tsd from time t6 to t7, and as shown in Fig. 8 (A), the feeding speed Fw is decelerated from the forward-running peak value Wsp to zero. At the same time, as shown in Fig. 8C, the welding voltage Vw rapidly decreases to a short-circuit voltage value of several V, and the welding current Iw gradually increases during the short-circuit period as shown in Fig. 8B .

Fig. 9 is a timing chart of each signal in the welding power supply of Fig. 7 showing the operation of variable feed rate control in the arc welding control method according to the fourth embodiment of the present invention. Fig. FIG. 9A shows the time variation of the feed chip-base material distance Lw, FIG. 9B shows the time variation of feed rate average value Fav, and FIG. 9C shows the welding current smoothing signal Iav ( 9 (D) shows the time change of the forwarding acceleration period setting signal Tsur, and FIG. 9 (E) shows the time of the backward deceleration period setting signal Trdr Change. Fig. 9 shows the transient response of each signal when the distance Lw between the feeding chip and the parent material during welding is extended from L1 (mm) to L2 (mm) at time t1. The feed rate average value Fav represents an average value of feed rate Fw shown in FIG. 8 (A) every one cycle. The time scale of FIG. 9 is 5 to 10 times longer than that of FIG. This will be described below with reference to Fig.

During the period before time t1, as shown in Fig. 9A, since the distance Lw between the power supply chip and the parent material is in a constant state of L1 (mm), the welding current The value of the smoothing signal Iav is in the same state as the value of the current setting signal Ir indicated by the broken line. Therefore, the values of the forwarding acceleration period setting signal Tsur shown in (D) of FIG. 9 and the forwarding deceleration period setting signal Trdr shown in (E) of FIG. 9 are constant values, As shown in the figure, the feed rate average value Fav is in a substantially constant state.

When the distance between the welding torch and the base material becomes long at time t1, the distance Lw between the power supply chip and the base material becomes longer from L1 to L2 as shown in Fig. 9 (A). 9C, the value of the welding current smoothing signal Iav decreases with a slope from the time t1, and the value of the current setting signal Ir is compared with the error (the feeding error amplification signal Ef > 0) Lt; / RTI > 9 (D) is changed from the time t1 to the inclination at the time t1 by keeping the value of the welding current smoothing signal Iav at a constant value by the feed-rate varying control for returning the error to zero And the trapezoidal deceleration period setting signal Trdr shown in (E) of FIG. 9 becomes smaller with a slope from the time t1. In response to this, as shown in Fig. 9 (B), the feed rate average value Fav accelerates from the time t1 with a slope.

The value of the welding current smoothing signal Iav is decreased from the time t1 as shown in Fig. 9 (C), reversed from decrease to increase at the time t2, returned to the value before the time t1 at the time t3 The error with the current setting signal Ir becomes substantially zero. The forwarding acceleration period setting signal Tsur shown in (D) of FIG. 9 gradually increases from time t1 and converges to a value larger than the value before time t1 from time t3. Further, the trapezoidal deceleration period setting signal Trdr shown in (E) of Fig. 9 gradually decreases from time t1 and converges to a value smaller than the time t1 before time t1. In response to this, as shown in Fig. 9B, the feed rate average value Fav gradually increases from time t1 and converges to a value higher than the value before time t1 from time t3.

When the distance Lw between the feeding chip and the base material is changed in the direction of shortening, the value of the welding current smoothing signal Iav is once returned to its original value after being increased. The forwarding acceleration period setting signal Tsur converges to a value smaller than the value before the change and the traverse deceleration period setting signal Trdr converges to a larger value than before the change and the feeding rate average value Fav converges to a value lower than the value before the change. The transient period of time t1 to t3 is about 50 to 100 ms. The cycle of feeding speed is about 10 ms.

In the above example, the waveform parameter of the feeding feed rate Fw to be feedback-controlled is the forwarding acceleration period Tsu and the backward deceleration period Trd. The waveform parameter of the feed rate Fw to be fed-back controlled is at least one of the forwarding acceleration period Tsu, the regular forward deceleration period Tsd, the backpropagation acceleration period Tru, the backward deceleration period Trd, the forwarding amplitude (the forwarding peak value Wsp) One may be used.

The welding condition can be further stabilized by feedback control of at least one of the forwarding acceleration period Tsu, the trailing acceleration / deceleration period Trd, or the forwarding peak value Wsp, which is in the arc period, from among the waveform parameters of the feeding rate Fw.

According to the fourth embodiment described above, the smoothing value of the welding current is detected, and the smoothing acceleration period, the forwarding deceleration period, the reverse acceleration period, the reverse deceleration period, At least one of the amplitude or the traction amplitude is feedback-controlled. Thus, in the present embodiment, the welding current smoothness value can be kept constant even when the distance between the feed chip and the base material is varied in the welding for alternately switching the feeding period and the feeding period. Therefore, can do.

According to the present invention, even when the distance between the feeding chip and the base material is changed, the welding current smoothed value can be kept constant in the welding for alternately switching the forwarding period and the backing period of the feeding speed, so that the penetration depth can be made uniform .

While the present invention has been described with reference to the specific embodiments thereof, it is to be understood that the invention is not limited to those embodiments, but various modifications are possible without departing from the technical idea of the disclosed invention.

The present application is based on Japanese Patent Application (Japanese Patent Application No. 2014-165777) filed on August 18, 2014, Japanese Patent Application (Japanese Patent Application No. 2015-008198) filed on January 20, 2015, The contents are included here.

1: welding wire
2: base material
3: arc
4: welding torch
5: Feed roll
DV: drive circuit
Dv: drive signal
E: Output voltage
EA: voltage error amplifier circuit
Ea: voltage error amplified signal
ED: Output voltage detection circuit
Ed: Output voltage detection signal
EF: Feeding error amplification circuit
Ef: Feeding error amplification signal
EF2: Second feeding error amplifying circuit
ER: Output voltage setting circuit
Er: Output voltage setting signal
Fav: Feed rate average
FC: feed control circuit
Fc: feed control signal
FR: feed rate setting circuit
Fr: feed rate setting signal
FR2: 2nd feeding speed setting circuit
FR3: 3rd feeding speed setting circuit
Fw: feed rate
IAV: current smoothing circuit
Iav: Welding current smoothed signal
ID: Current detection circuit
Id: current detection signal
IR: current setting circuit
Ir: current setting signal
Iw: welding current
Lw: distance between feed chip and parent material
PM: Power main circuit
SD: Short circuit discrimination circuit
Sd: Paragraph signal
Sf: forward shift amount
SFR: forward shift amount setting circuit
Sfr: Positive shift amount setting signal
Tar: Ark period Back period
Tas: Ark period
Tf: cycle
TFR: Period setting circuit
Tfr: Period setting signal
Trd: Reverse feed deceleration period
TRDR: Tuning deceleration period setting circuit
Trdr: Reverse deceleration period setting signal
Trp: reverse-return peak period
Tru: Reverse acceleration period
TRUR: Reverse acceleration period setting circuit
Trur: Reverse acceleration period setting signal
Tsd: forward deceleration period
TSDR: Constant deceleration period setting circuit
Tsdr: Signal to set the forward deceleration period
Tsp: Peak period
Tsu: Fast forward acceleration period
TSUR: Acceleration period setting circuit
Tsur: Acceleration period setting signal
VD: Voltage detection circuit
Vd: voltage detection signal
Vw: welding voltage
Wf: Amplitude
WFR: Amplitude setting circuit
Wfr: Amplitude setting signal
WL: Reactor
WM: Feeding motor
Wrp: reverse peak value
WRR: Reverse Amplitude Setting Circuit
Wrr: Reverse signal amplitude setting signal
Wsp: forward peak value
WSR: forward amplitude setting circuit
Wsr: Constant amplitude setting signal

Claims (5)

An arc welding control method for alternately switching the feeding speed of a welding wire to a forwarding period and a backing period, repeating a short-circuit period and an arc period,
And a waveform parameter of the feeding speed is feedback-controlled so that a smoothed value of the welding current is detected and a smoothed value of the welding current is equal to a predetermined current setting value. The method according to claim 1,
Wherein the waveform parameter is an amplitude and / or a forward shift amount. The method according to claim 1,
Wherein the waveform parameter is at least one of a forwarding acceleration period, a forwarding decelerating period, a backward acceleration period, a backward deceleration period, a forwarding amplitude, or a backward amplification amplitude. 4. The method according to any one of claims 1 to 3,
Wherein the feedback control is performed only when the current setting value is equal to or greater than a predetermined reference current value. 4. The method according to any one of claims 1 to 3,
Wherein the feedback-controlled waveform parameter is changed in synchronization with a specific timing in the short-circuit period.

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