JP6532138B2 - Arc welding control method - Google Patents

Description

  The present invention relates to an arc welding control method of alternately switching a feeding speed of a welding wire between a forward feeding period and a reverse feeding period, repeating a short circuit period and an arc period, and passing a welding current to perform welding.

  In general consumable electrode arc welding, welding is performed by feeding a consumable welding wire at a constant speed and generating an arc between the welding wire and a base material. In consumable electrode type arc welding, a welding state often occurs in which a welding wire and a base material alternately repeat a short circuit period and an arc period.

  In order to further improve the welding quality, a method has been proposed in which welding is periodically repeated with forward feeding and reverse feeding of the welding wire. In the invention of Patent Document 1, the average value of the feeding speed according to the set value of welding current is used, and the frequency and the amplitude of forward feeding and reverse feeding of the welding wire are set according to the set value of welding current. In the welding method in which the forward feed and the reverse feed of the welding wire are repeated, it is possible to set the repetition cycle of the short circuit and the arc which can not be achieved by the prior art of constant speed feed to desired values. The welding quality can be improved such as the reduction of

  In the invention of Patent Document 2, the welding wire is positively fed, and the feeding speed of the welding wire is feedback-controlled to perform feeding speed variable control so that the welding current and the predetermined current setting value become equal. In conventional consumable electrode arc welding, the feed rate during welding is a constant value. On the other hand, in 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 tip and the base material changes. Since the penetration depth of the base material is approximately proportional to the welding current value, the penetration depth becomes uniform when the welding current value becomes constant. In ordinary arc welding, welding is performed while keeping the distance between the feed tip and the base material constant. However, in the case of deep groove welding, multi-layer welding, etc., it may be difficult to maintain the distance between the feeding tip and the base material at a constant value due to the problem of interference between the welding torch and the base material. . Thus, in welding where the distance between the feed tip and the base material varies, the invention of Patent Document 2 variably controls the feed speed to maintain a constant welding current value, which is one of the important welding qualities. Variations in penetration depth can be suppressed and made uniform.

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

  In the present invention, in welding in which the forward feed period and the reverse feed period of feed speed are alternately switched, an arc welding control method capable of equalizing the penetration depth even if the distance between the feed tip and the base material changes. Intended to provide.

In order to solve the problems described above, the arc welding control method of the present invention is:
In the arc welding control method of alternately switching the feeding speed of the welding wire between the forward feeding period and the reverse feeding period, repeating the shorting period and the arcing period, and applying welding current for welding,
A smooth value of the welding current is detected, and feedback control of the waveform parameter of the feeding speed is performed so that the welding current smooth value is equal to a predetermined current setting value.
It is characterized by

In the arc welding control method of the present invention, the waveform parameter is an amplitude and / or a forward shift amount.
It is characterized by

In the arc welding control method of the present invention, the waveform parameter is at least one of a forward acceleration period, a forward deceleration period, a reverse acceleration period, a reverse acceleration period, a forward amplitude or a reverse amplitude.
It is characterized by

In the arc welding control method of the present invention, the feedback control is performed only when the current setting value is equal to or more than a predetermined reference current value.
It is characterized by

In the arc welding control method of the present invention, the feedback controlled waveform parameter changes in synchronization with a specific timing during the short circuit period.
It is characterized by

  According to the present invention, it is possible to keep the welding current smooth value constant even if the distance between the feeding tip and the base material changes in welding in which the forward feeding period and the reverse feeding period of feeding speed are alternately switched. The penetration depth can be made uniform.

It is a block diagram of a welding power supply for enforcing the arc welding control method concerning Embodiment 1 of the present invention. It is a timing chart of each signal in the welding power supply of FIG. 1 which shows the arc welding control method which concerns on Embodiment 1 of this invention. In the arc welding control method which concerns on Embodiment 1 of this invention, it is a timing chart of each signal in the welding power supply of FIG. 1 which shows operation | movement of feed speed variable control. It is a block diagram of a welding power supply for enforcing the arc welding control method concerning Embodiment 2 of the present invention. It is a block diagram of a welding power supply for enforcing the arc welding control method concerning Embodiment 3 of the present invention. It is a timing chart of each signal in the welding power supply of FIG. 5 which shows the arc welding control method concerning Embodiment 3 of this invention. It is a block diagram of a welding power supply for enforcing the arc welding control method concerning Embodiment 4 of the present invention. It is a timing chart of each signal in the welding power supply of Drawing 7 which shows the arc welding control method concerning Embodiment 4 of the present invention. In arc welding control method concerning Embodiment 4 of the present invention, it is a timing chart of each signal in welding power supply of Drawing 7 which shows operation of feed speed variable control.

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

First Embodiment
The invention of the first embodiment performs feedback control of the amplitude and / or the forward shift amount, which is the waveform parameter of the feed speed, so that the smooth value of the welding current and the predetermined current setting value become equal. is there.

  FIG. 1 is a block diagram of a welding power source for carrying out an arc welding control method according to a first embodiment of the present invention. Each block will be described below with reference to the figure.

  Power supply main circuit PM receives a commercial power supply (not shown) such as three-phase 200 V, performs output control by inverter control or the like according to a drive signal Dv described later, and outputs output voltage E. Although not shown, the power supply main circuit PM is driven by a primary rectifier that rectifies a commercial power supply, a smoothing capacitor that smoothes rectified direct current, and the above-mentioned drive signal Dv that converts smoothed direct current into high frequency alternating current. Inverter circuit, a high frequency transformer that steps down high frequency alternating current to a voltage value suitable for welding, and a secondary rectifier that rectifies reduced high frequency alternating current to direct current.

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

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

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

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

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

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

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

  The current setting circuit IR outputs a predetermined current setting signal Ir which is a target current value in the feed speed variable control. The feed error amplification circuit EF amplifies the error between the current setting signal Ir (+) and the welding current smooth signal Iav (−) and outputs a feed error amplification signal Ef.

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

  The amplitude setting circuit WFR takes the above-mentioned feed error amplification signal Ef as an input, integrates the feed error amplification signal Ef during welding, and outputs an amplitude setting signal Wfr. The integral can be expressed as Wfr = Wf0 + ∫Ef · dt. Here, Wf0 is a predetermined initial value. By this circuit, the value of the amplitude setting signal Wfr is feedback-controlled so that the value of the welding current smooth signal Iav becomes equal to the value of the current setting signal Ir, and welding changes every moment.

  The normal feed side shift amount setting circuit SFR receives the above-mentioned feed error amplified signal Ef, integrates the feed error amplified signal Ef during welding, and outputs a positive feed side shift amount set signal Sfr. The integral can be expressed as Sfr = Sf0 + ∫Ef · dt. Here, Sf0 is a predetermined initial value. By this circuit, the value of the positive shift value setting signal Sfr is feedback-controlled so that the value of the welding current smooth signal Iav becomes equal to the value of the current setting signal Ir, and the welding changes every moment.

  The feed speed setting circuit FR receives the above cycle setting signal Tfr, the above amplitude setting signal Wfr and the above forward shift amount setting signal Sfr, and is determined by the cycle and amplitude setting signal Wfr determined by the cycle setting signal Tfr. A feeding speed pattern in which a sine wave formed from the amplitude is shifted by the forward shift amount determined by the forward shift amount setting signal Sfr is output as a feed speed setting signal Fr. When the feed speed setting signal Fr is 0 or more, it is a forward feed period, and when it is less than 0, it is a reverse feed period.

  Feed control circuit FC receives feed speed setting signal Fr described above, and feeds control signal Fc for feeding welding wire 1 at a feed speed Fw corresponding to the value of feed speed setting signal Fr. It outputs to the above-mentioned feed motor WM.

  FIG. 2 is a timing chart of each signal in the welding power source of FIG. 1 showing the arc welding control method according to the first embodiment of the present invention. The figure (A) shows the time change of feed speed Fw, the figure (B) shows the time change of welding current Iw, and the figure (C) shows the time change of welding voltage Vw. This will be described below with reference to the same figure.

  As shown in FIG. 6A, the feed speed Fw is a forward feed period above 0 and a reverse feed period below 0. The forward feeding is to feed the welding wire in the direction approaching the base material, and the reverse feeding is to feed in the direction away from the base material. The feed speed Fw changes in a sinusoidal manner and has a waveform shifted to the positive feed side. For this reason, the average value of the feed speed Fw is a positive value, and the welding wire is fed positively on average. The feed speed pattern of the feed speed Fw may be a triangular wave, a trapezoidal wave or the like.

  As shown in FIG. 6A, the feed speed Fw is 0 at time t1, and the period from time t1 to t2 is a forward acceleration period, and the maximum value for forward transmission at time t2 is obtained. The period t3 is a forward feed deceleration period, it becomes 0 at time t3, the period from time t3 to t4 is a reverse feed acceleration period, the maximum value of reverse feed is at time t4, and the period from time t4 to t5 is a reverse feed deceleration period It becomes. Then, the period from time t5 to t6 becomes the forward feed acceleration period again, and the period from time t6 to t7 becomes the forward feed deceleration period again. Therefore, the feed speed Fw has a cycle Tf (ms) from time t1 to t5, an amplitude Wf (m / min) which is the difference between the maximum value of forward transmission at time t2 and the maximum value of backward transmission at time t4 and It repeats with the feed speed pattern of the sending side shift amount Sf (m / min). Here, the cycle Tf is set to a predetermined value by the cycle setting circuit TFR of FIG. The amplitude Wf is feedback-controlled by the feed error amplification circuit EF and the amplitude setting circuit WFR in FIG. 1 so that the value of the welding current smooth 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 amplification circuit EF and the forward shift amount setting circuit SFR in FIG. 1 so that the value of the welding current smooth signal Iav becomes equal to the value of the current setting signal Ir. Ru. The period Tf is set to about 8 to 20 ms, the amplitude Wf changes in a range of about 30 to 100 m / min, and the forward shift amount Sf changes in a range of about 3 to 20 m / min.

  A short circuit between the welding wire and the base material often occurs around the positive feed maximum value at time t2. In the same figure, it is a case where it occurs at time t21 during the normal feed deceleration period after the normal feed maximum value. When a short circuit occurs at time t21, as shown in FIG. 7C, welding voltage Vw sharply decreases to a short circuit voltage value of several volts, and as shown in FIG. 7B, welding current Iw gradually increases.

  As shown in FIG. 6A, since the feed speed Fw is in the reverse feed period from time t3, the welding wire is fed backward. By this reverse feed, the short circuit is released and the arc is regenerated at time t31. Regeneration of the arc often occurs before and after the maximum value of reverse sending at time t4. In the same figure, it is a case where it occurs at time t31 during the backward acceleration period before the backward maximum value. Therefore, the period from time t21 to t31 is a short circuit period.

  When an arc is regenerated at time t31, the welding voltage Vw sharply increases to an arc voltage value of several tens of volts as shown in FIG. As shown in FIG. 6B, the welding current Iw starts to change from the state of the maximum value during the short circuit period.

  During the period from time t31 to time t5, as shown in FIG. 6A, since the feed speed Fw is in the reverse feed state, the welding wire is pulled up and the arc length gradually becomes longer. When the arc length is increased, welding voltage Vw is increased, and welding current Iw is reduced because constant voltage control is performed by voltage error amplification circuit EA of FIG. Therefore, during the arc period reverse transfer period Tar at times t31 to t5, as shown in FIG. 7C, welding voltage Vw gradually increases, and as shown in FIG. 7B, welding current Iw gradually decreases. Become.

  Then, the next short circuit occurs at time t61 during the forward feed deceleration period from time t6 to t7. However, in the short circuit occurring at time t61, the time (phase) from the positive feed maximum value is later than the short circuit occurring at time t21. The timing at which the short circuit occurs has a certain degree of variation. A period of time t31 to t61 is an arc period. During the period from time t5 to t61, as shown in FIG. 6A, the feed speed Fw is in the normal feed state, so the welding wire is positively fed and the arc length is gradually shortened. When the arc length becomes short, welding voltage Vw becomes small, and since constant voltage control is performed by voltage error amplification circuit EA of FIG. 1, welding current Iw becomes large. Therefore, during the arc period positive feeding period Tas from time t5 to t61, the welding voltage Vw becomes gradually smaller as shown in (C), and the welding current Iw becomes larger gradually as shown in (B). Become.

  FIG. 3 is a timing chart of each signal in the welding power source of FIG. 1 showing the operation of feed speed variable control in the arc welding control method according to the first embodiment of the present invention. The figure (A) shows the time change of the distance Lw between the feeding tip and the base material, the figure (B) shows the time change of the feed speed average value Fav, the figure (C) shows the welding current smooth signal Iav ( (D) shows the time change of the amplitude setting signal Wfr, and (E) shows the time change of the forward shift amount setting signal Sfr. Show. The figure shows the transient response of each signal when the distance Lw between the feeding tip and the base material is increased from L1 (mm) to L2 (mm) at time t1 during welding. The above-described feed speed average value Fav indicates the average value of the feed speed Fw shown in FIG. 2A for each cycle. The time scale in the figure is five to ten times longer than in FIG. This will be described below with reference to the same figure.

  During the period before time t1, as shown in FIG. 6A, since the distance Lw between the feeding tip and the base material is in a constant state of L1 (mm), the welding current shown by the solid line in FIG. The value of the smoothed signal Iav is in a state equal to the value of the current setting signal Ir indicated by a broken line. For this reason, since each value of the amplitude setting signal Wfr shown in FIG. 5D and the forward shift amount setting signal Sfr shown in FIG. 5E becomes a constant value, as shown in FIG. The feed speed average value Fav is in a substantially constant state.

  When the distance between the welding torch and the base material increases at time t1, as shown in FIG. 6A, the distance Lw between the feed tip and the base material increases from L1 to L2. For this reason, as shown in FIG. 6C, the value of welding current smooth signal Iav decreases with a slope from time t1, and the value of current setting signal Ir and the error (feed error amplified signal Ef> 0) occurs. In order to maintain the value of welding current smooth signal Iav at a constant value by feed speed variable control that returns this error to 0, the amplitude setting signal Wfr shown in FIG. 7D and the forward side shown in FIG. Both values of the shift amount setting signal Sfr increase with an inclination from time t1. In response to this, as shown in FIG. 7B, the feed speed average value Fav becomes faster with a slope from time t1.

  The value of welding current smooth signal Iav decreases from time t1 and reverses from decrease to increase at time t2 as shown in FIG. 6C, and returns to the value before time t1 at time t3 to set the current The error with the signal Ir is approximately zero. Both the values of the amplitude setting signal Wfr shown in FIG. 6D and the forward shift amount setting signal Sfr shown in FIG. 6E gradually increase from time t1 and are larger than those before time t1 at time t3. Converge on the value. In response to this, the feed speed average value Fav gradually increases from time t1 as shown in FIG. 7B, and converges to a value faster than the value before time t1 at time t3.

  When the distance Lw between the feeding tip and the base material changes in the direction of shortening, the value of the welding current smooth signal Iav once increases and then returns to the original value. Both values of the amplitude setting signal Wfr and the forward shift value setting signal Sfr converge to a smaller value than the value before change, and the feed speed average value Fav converges to a slower value than the value before change. The transition period of time t1 to t3 is about 50 to 100 ms.

  According to the above-described first embodiment, the smoothed value of the welding current is detected, and the amplitude of the feeding speed and / or the forward feed side shift so that the welding current smoothed value and the predetermined current setting value become equal. Feedback control the amount. Thus, in the present embodiment, in welding in which the forward feed period and the reverse feed period of feed speed are alternately switched, the welding current smooth value is kept constant even if the distance between the feed tip and the base metal changes. As a result, the penetration depth can be made uniform. At this time, it is desirable to feedback control both the feed speed amplitude and the forward shift amount. This is because the stability of the welding state is improved as compared to when feedback control is performed on only one side.

Second Embodiment
The invention of the second embodiment is to perform feedback control (feed speed variable control) only when the current setting value is equal to or more than a predetermined reference current value.

  FIG. 4 is a block diagram of a welding power source for implementing an arc welding control method according to a second embodiment of the present invention. This figure corresponds to FIG. 1 described above, and the same reference numerals are given to the same blocks and their description will not be repeated. This figure is obtained by replacing the feed error amplification circuit EF of FIG. 1 with a second feed error amplification circuit EF2. Hereinafter, this block will be described with reference to the figure.

  The second feed error amplification circuit EF2 receives the current setting signal Ir, and when the value of the current setting signal Ir is equal to or greater than a predetermined reference current value, the current setting signal Ir (+) and the welding current smoothing signal Iav (− And the feed error amplified signal Ef is outputted, and when the value of the current setting signal Ir is smaller than the above reference current value, the feed error amplified signal Ef which becomes 0 is outputted. Thus, feedback control of the amplitude setting signal Wfr and the forward shift amount setting signal Sfr is performed only when the value of the current setting signal Ir is equal to or more than the reference current value. The reference current value is set to about 200A.

  According to the second embodiment described above, feedback control (feed 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. The variable feeding speed control is prohibited because the welding state may become unstable if the feeding speed variable control is performed when the current setting value is less than the reference current value. Also, if the current setting value is less than the reference current value, the welding condition becomes unstable if the distance between the feeding tip and the base material is changed, so welding is performed without changing the distance.

Third Embodiment
The invention of the third embodiment is that the amplitude and / or the forward shift amount under feedback control is changed in synchronization with a specific timing during the short circuit period. In the first embodiment, the cycle of the feed speed and / or the forward shift amount changes asynchronously every moment at an arbitrary timing of the feed speed by feedback control. On the other hand, in the third embodiment, the period and / or the forward shift amount changes in synchronization with the specific timing during the short circuit period, and does not change at other timings.

  FIG. 5 is a block diagram of a welding power source for implementing an arc welding control method according to a third embodiment of the present invention. This figure corresponds to FIG. 1 described above, and the same reference numerals are given to the same blocks and their description will not be repeated. In this figure, the voltage detection circuit VD and the short circuit discrimination circuit SD are added to FIG. 1, and the feed speed setting circuit FR of FIG. 1 is replaced with a second feed speed setting circuit FR2. Hereinafter, these blocks will be described with reference to the figure.

  The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The short circuit discrimination circuit SD takes the above voltage detection signal Vd as an input, and when this value is less than a predetermined short circuit discrimination value (about 10 V), it determines that it is in a short circuit period and becomes High level. It determines that it is in the arcing period, and outputs a short circuit determination signal Sd that goes low.

  The second feed speed setting circuit FR2 receives the short circuit determination signal Sd, the cycle setting signal Tfr, the amplitude setting signal Wfr, and the forward shift amount setting signal Sfr, and receives the cycle setting signal Tfr. The values of the amplitude setting signal Wfr and the forward shift value setting signal Sfr are read in synchronization with the timing when the short circuit discrimination signal Sd changes to the high level (short circuit), and the period and amplitude setting signal Wfr determined by the period setting signal Tfr A feeding speed pattern is output as a feeding speed setting signal Fr, in which a sine wave formed from the amplitude determined by the above is shifted by the normal sending side shift amount determined by the normal sending side shift amount setting signal Sfr. That is, each waveform parameter of the feed speed setting signal Fr is updated in synchronization with a specific timing during the short circuit period. The specific timing is a timing at which a short circuit occurs, a timing after a predetermined period after the short circuit occurs, a timing at which the feed speed setting signal Fr changes from forward to reverse during a short circuit period.

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

  When a short circuit occurs at time t21, the values of the cycle setting signal Tfr, the amplitude setting signal Wfr and the forward shift amount setting signal Sfr are synchronized with the short circuit occurrence timing by the second feed speed setting circuit FR2 of FIG. Read and update. At this time, since the cycle 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 are changed by feedback control, the amplitude Wf of the feed speed Fw and the forward shift amount are changed at time t21 as shown in FIG. Sf is large. The same applies to time t61 at which the next short circuit occurs. Thus, 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 is a timing when the short circuit occurs, a timing after a predetermined period after the short circuit occurs, a timing when the forward feed changes to the reverse feed during the short circuit (time t3) is there.

  The reason for changing the amplitude Wf of the feed speed Fw and the forward shift amount Sf during the short circuit period is that the welding state may become unstable if the waveform of the feed speed Fw suddenly changes during the arc period. It is. During the short circuit period, even if the feed speed Fw suddenly changes, the influence on the welding state is small.

  In the arc welding control method according to the third embodiment of the present invention, the timing chart of each signal in the welding power source of FIG. 5 showing the operation of feed speed variable control is the same as that of FIG. Absent. Although the third embodiment is based on the first embodiment, the same applies to the second embodiment.

  According to the third embodiment described above, the amplitude and / or the forward shift amount changes in synchronization with the specific timing during the short circuit period. Thus, in the present embodiment, the waveform parameter of the feed speed is updated during the short circuit period, so that the welding state can be stably maintained.

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

Fourth Embodiment
The invention of the fourth embodiment is characterized in that the forward feed acceleration period, the forward feed deceleration period, and the reverse feed acceleration period, which are waveform parameters of the feed speed, so that the smooth value of the welding current and the predetermined current setting value become equal. The feedback control is performed to feedback control at least one of the forward feed deceleration period and the forward feed amplitude or the reverse feed amplitude. Then, the waveform parameter under feedback control changes in synchronization with the specific timing during the short circuit period.

  FIG. 7 is a block diagram of a welding power source for implementing the arc welding control method according to the fourth embodiment of the present invention. This figure corresponds to FIG. 5 described above. The same reference numerals are given to the same blocks, and the description thereof will not be repeated. In this figure, the cycle setting circuit TFR, the amplitude setting circuit WFR and the forward shift amount setting circuit SFR in FIG. 5 are deleted. Then, the second feed error amplification circuit EF2 identical to that of FIG. A forward feed amplitude setting circuit WSR and a reverse feed amplitude setting circuit WRR are added. Furthermore, the second feed speed setting circuit FR2 of FIG. 5 is replaced with a third feed speed setting circuit FR3. Hereinafter, these blocks will be described with reference to the figure.

  The second feed error amplification circuit EF2 receives the current setting signal Ir, and when the value of the current setting signal Ir is equal to or greater than a predetermined reference current value, the current setting signal Ir (+) and the welding current smoothing signal Iav (− And the feed error amplified signal Ef is outputted, and when the value of the current setting signal Ir is smaller than the above reference current value, the feed error amplified signal Ef which becomes 0 is outputted. Thus, feedback control is performed only when the value of the current setting signal Ir is equal to or greater than the reference current value. The reference current value is set to about 200A.

  A forward feed acceleration period setting circuit TSUR receives the above feed error amplified signal Ef, integrates the feed error amplified signal Ef during welding, and outputs a positive feed acceleration period setting signal Tsur. The integral can be expressed as Tsur = Tsu0 + ∫Ef · dt. Here, Tsu0 is a predetermined initial value. By this circuit, the value of the positive feed acceleration period setting signal Tsur is feedback-controlled so that the value of the welding current smooth signal Iav becomes equal to the value of the current setting signal Ir, and the welding changes from time to time.

  The forward feed deceleration period setting circuit TSDR outputs a preset forward feed deceleration period setting signal Tsdr.

  The reverse feed acceleration period setting circuit TRUR outputs a preset reverse feed acceleration period setting signal Trur.

  The reverse feed deceleration period setting circuit TRDR receives the feed error amplified signal Ef as an input, integrates the feed error amplified signal Ef during welding, and outputs a reverse feed deceleration period setting signal Trdr. The integral can be expressed as Trdr = Trd0−∫Ef · dt. Here, Trd0 is a predetermined initial value. By this circuit, the value of the reverse feed deceleration period setting signal Trdr is feedback-controlled so that the value of the welding current smooth signal Iav becomes equal to the value of the current setting signal Ir, and the welding changes from time to time.

  The positive feed amplitude setting circuit WSR outputs a predetermined positive feed amplitude setting signal Wsr. The reverse feed amplitude setting circuit WRR outputs a predetermined reverse feed amplitude setting signal Wrr.

The third feed speed setting circuit FR3 has the above-mentioned forward feed acceleration period setting signal Tsur, the above-mentioned forward feed deceleration period setting signal Tsdr, the above-mentioned reverse feed acceleration period setting signal Trur, the above-mentioned reverse feed deceleration period setting signal Trdr, The above-mentioned forward feed amplitude setting signal Wsr, the above reverse feed amplitude setting signal Wrr and the above short circuit discrimination signal Sd are input, and a feed speed pattern generated by the following processing is outputted as a feed speed set signal Fr. When the feed speed setting signal Fr is 0 or more, it is a forward feed period, and when it is less than 0, it is a reverse feed period. Also, the waveform parameters (Tsur, Tsdr, Trur, Trdr, Wsr and Wrr) of the feed speed are updated in synchronization with the specific timing during the short circuit period. The specific timing is a timing at which a short circuit occurs, a timing after a predetermined period after the short circuit occurs, a timing at which the feed speed setting signal Fr changes from forward to reverse during a short circuit period.
1) During the normal feed acceleration period Tsu determined by the positive feed acceleration period setting signal Tsur, the feed speed setting signal Fr that linearly accelerates from 0 to a positive value positive feed peak value Wsp determined by the positive feed amplitude setting signal Wsr Output.
2) Subsequently, during the forward delivery peak period Tsp, the delivery speed setting signal Fr for maintaining the above-mentioned forward delivery peak value Wsp is output.
3) When the short circuit discrimination signal Sd changes from the low level (arcing period) to the high level (short circuiting period), the waveform parameter of the feeding speed is read and updated. At the same time, a feed speed setting signal Fr is output which shifts to a normal feed deceleration period Tsd determined by the positive feed deceleration period setting signal Tsdr, and linearly decelerates from the positive feed peak value Wsp to 0 described above.
4) Subsequently, during the reverse acceleration period Tru determined by the reverse acceleration period setting signal Trur, the feed speed setting is linearly accelerated from 0 to a negative reverse peak value Wrp determined by the reverse amplitude setting signal Wrr. It outputs a signal Fr.
5) Subsequently, during the reverse transfer peak period Trp, the transfer speed setting signal Fr for maintaining the above-described reverse transfer peak value Wrp is output.
6) When the short circuit discrimination signal Sd changes from the high level (short circuit period) to the low level (arc period), it shifts to the reverse transfer deceleration period Trd determined by the reverse transfer deceleration period setting signal Trdr, and from the above reverse transfer peak value Wrp A feed speed setting signal Fr that linearly decelerates to 0 is output.
7) By repeating the above 1) to 6), the feed speed setting signal Fr of the feed pattern changing in the positive and negative trapezoidal wave form is generated.

  FIG. 8 is a timing chart of each signal in the welding power source of FIG. 7 showing the arc welding control method according to the fourth embodiment of the present invention. The figure (A) shows the time change of feed speed Fw, the figure (B) shows the time change of welding current Iw, the figure (C) shows the time change of welding voltage Vw, the figure (D) Shows the time change of the short circuit discrimination signal Sd. The operation of each signal will be described below with reference to FIG.

  The feed speed Fw shown in FIG. 7A is controlled to the value of the feed speed setting signal Fr output from the third feed speed setting circuit FR3 of FIG. The feed speed Fw is a forward feed acceleration period Tsu under feedback control by the forward feed acceleration period setting signal Tsur in FIG. 7, a forward feed peak period Tsp continuing until a short circuit occurs, and a forward feed deceleration period setting signal Tsdr in FIG. By the reverse feed acceleration period Tru determined by the reverse feed acceleration period setting signal Trur of FIG. 7, the reverse feed peak period Trp continuing until an arc is generated, and the reverse feed deceleration period setting signal Trdr of FIG. 7. It is formed from the reverse feedback deceleration period Trd which is feedback controlled. Further, the forward transmission peak value Wsp is determined by the forward transmission amplitude setting signal Wsr in FIG. 7, and the reverse transmission peak value Wrp is determined by the reverse transmission amplitude setting signal Wrr in FIG. As a result, the feed speed setting signal Fr has a feed pattern that changes in a positive and negative trapezoidal wave shape. As in the second embodiment, feedback control of the waveform parameter of the feed speed Fw is performed only when the value of the current setting signal Ir is equal to or more than the reference current value. Furthermore, the waveform parameter of the feed speed Fw subjected to feedback control changes in synchronization with the specific timing of the short circuit period.

[Operation of reverse sending period from time t1 to t4]
As shown in FIG. 6A, the feed speed Fw enters a predetermined reverse feed acceleration period Tru from time t1 to t2, and accelerates from 0 to the above-mentioned reverse feed peak value Wrp. During this period, the short circuit period continues.

  When the backward acceleration period Tru ends at time t2, as shown in (A) of the figure, the feed speed Fw enters the backward transmission peak period Trp and becomes the above-mentioned backward peak value Wrp. The short circuit period continues also during this period.

  When an arc occurs at time t3, the short circuit discrimination signal Sd changes to the low level (arcing period) as shown in FIG. In response to this, it shifts to a predetermined reverse feed deceleration period Trd from time t3 to t4, and as shown in FIG. 6A, the feed speed Fw decelerates from the above-mentioned reverse feed peak value Wrp to 0. . At the same time, as shown in FIG. 4C, the welding voltage Vw sharply increases to an arc voltage value of several tens of volts, and as shown in FIG. 4B, the welding current Iw gradually decreases during the arc period.

[Operation of the forward sending period from time t4 to t7]
When the reverse feed deceleration period Trd ends at time t4, the process shifts to a predetermined forward feed acceleration period Tsu from time t4 to t5. During the forward feed acceleration period Tsu, as shown in FIG. 7A, the feed speed Fw accelerates from 0 to the above-mentioned positive feed peak value Wsp. The arcing period continues during this period.

  When the positive feed acceleration period Tsu ends at time t5, the feed speed Fw enters the positive feed peak period Tsp and becomes the positive feed peak value Wsp as shown in FIG. The arcing period continues during this period.

  When a short circuit occurs at time t6, as shown in FIG. 6D, the short circuit discrimination signal Sd changes to the high level (short circuit period), and the forward feed acceleration period setting signal Tsur and the reverse feed deceleration period under feedback control are performed. The setting signal Trdr is read and updated in synchronization with the occurrence of a short circuit. In response to this, it shifts to a predetermined forward feed deceleration period Tsd from time t6 to t7, and the feed speed Fw is decelerated from the above-mentioned positive feed peak value Wsp to 0 as shown in FIG. . At the same time, as shown in FIG. 7C, the welding voltage Vw sharply decreases to a short circuit voltage value of several volts, and as shown in FIG. 7B, the welding current Iw gradually increases during the short circuit period.

  FIG. 9 is a timing chart of each signal in the welding power source of FIG. 7 showing the operation of feed speed variable control in the arc welding control method according to the fourth embodiment of the present invention. The figure (A) shows the time change of the distance Lw between the feeding tip and the base material, the figure (B) shows the time change of the feed speed average value Fav, the figure (C) shows the welding current smooth signal Iav ( (D) shows the time change of the forward transfer acceleration period setting signal Tsur, and (E) shows the time of the reverse transfer deceleration period setting signal Trdr. Indicates a change. The figure shows the transient response of each signal when the distance Lw between the feeding tip and the base material is increased from L1 (mm) to L2 (mm) at time t1 during welding. The above-described feed speed average value Fav indicates the average value of the feed speed Fw shown in FIG. 8A for each cycle. The time scale in the same figure is five to ten times longer than in FIG. This will be described below with reference to the same figure.

  During the period before time t1, as shown in FIG. 6A, since the distance Lw between the feeding tip and the base material is in a constant state of L1 (mm), the welding current shown by the solid line in FIG. The value of the smoothed signal Iav is in a state equal to the value of the current setting signal Ir indicated by a broken line. For this reason, the values of the forward transportation acceleration period setting signal Tsur shown in FIG. 6D and the reverse transportation deceleration period setting signal Trdr shown in FIG. Thus, the feed speed average value Fav is in a substantially constant state.

  When the distance between the welding torch and the base material increases at time t1, as shown in FIG. 6A, the distance Lw between the feed tip and the base material increases from L1 to L2. For this reason, as shown in FIG. 6C, the value of welding current smooth signal Iav decreases with a slope from time t1, and the value of current setting signal Ir and the error (feed error amplified signal Ef> 0) occurs. In order to maintain the value of welding current smooth signal Iav at a constant value by feed speed variable control that returns this error to 0, forward feed acceleration period setting signal Tsur shown in FIG. 6D has a slope from time t1. The reverse feed deceleration period setting signal Trdr shown in (E) of the figure becomes smaller with a slope from time t1. In response to this, as shown in FIG. 7B, the feed speed average value Fav becomes faster with a slope from time t1.

  The value of welding current smooth signal Iav decreases from time t1 and reverses from decrease to increase at time t2 as shown in FIG. 6C, and returns to the value before time t1 at time t3 to set the current The error with the signal Ir is approximately zero. The forward feed acceleration period setting signal Tsur shown in FIG. 6D gradually increases from time t1, and converges to a value larger than the value before time t1 at time t3. Further, the reverse feed deceleration period setting signal Trdr shown in FIG. 6E gradually decreases from time t1, and converges to a value smaller than the value before time t1 at time t3. In response to this, the feed speed average value Fav gradually increases from time t1 as shown in FIG. 7B, and converges to a value faster than the value before time t1 at time t3.

  When the distance Lw between the feeding tip and the base material changes in the direction of shortening, the value of the welding current smooth signal Iav once increases and then returns to the original value. The forward feed acceleration period setting signal Tsur converges to a smaller value than the value before change, the reverse feed deceleration period setting signal Trdr converges to a larger value than before change, and the feed speed average value Fav is a value before change It converges to a slower value. The transition period of time t1 to t3 is about 50 to 100 ms. The cycle of the feeding speed is about 10 ms.

  In the above, the case where the waveform parameters of the feed speed Fw subjected to feedback control are the forward feed acceleration period Tsu and the reverse feed deceleration period Trd is illustrated. The waveform parameters of the feed speed Fw subjected to feedback control are: forward acceleration period Tsu, forward deceleration period Tsd, reverse acceleration period Tru, reverse deceleration period Trd, forward amplitude (forward peak value Wsp) or reverse feed It may be at least one of the amplitudes (the reverse peak value Wrp).

  If at least one of the forward feed acceleration period Tsu, the reverse feed deceleration period Trd, or the forward feed peak value Wsp during the arc period among the waveform parameters of the feed speed Fw is feedback-controlled, the welding state is further stabilized. can do.

  According to the fourth embodiment described above, the smoothed value of the welding current is detected, and the forward feeding acceleration period, the forward feeding deceleration period, the reverse feeding are performed so that the welding current smooth value and the predetermined current setting value become equal. Feedback control is performed on at least one of an acceleration period, a reverse feed deceleration period, a forward feed amplitude or a reverse feed amplitude. Thus, in the present embodiment, in welding in which the forward feed period and the reverse feed period of feed speed are alternately switched, the welding current smooth value is kept constant even if the distance between the feed tip and the base metal changes. As a result, the penetration depth can be made uniform.

  According to the present invention, it is possible to keep the welding current smooth value constant even if the distance between the feeding tip and the base material changes in welding in which the forward feeding period and the reverse feeding period of feeding speed are alternately switched. The penetration depth can be made uniform.

Although the present invention has been described above by the specific embodiment, the present invention is not limited to this embodiment, and various modifications can be made without departing from the technical concept of the disclosed invention.
This application is based on the Japanese patent application filed on August 18, 2014 (Japanese Patent Application No. 2014-165777) and the Japanese patent application filed on January 20, 2015 (Japanese Patent Application No. 2015-008198), the contents of which are It is taken in here.

Reference Signs List 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 amplification circuit Ea voltage error amplification signal ED output voltage detection circuit Ed output voltage detection signal EF delivery error amplification circuit Ef Feed error amplification signal EF2 Second feed error amplification circuit ER Output voltage setting circuit Er Output voltage setting signal Fav Feed speed average value FC Feed control circuit Fc Feed control signal FR Feed speed setting circuit Fr Feed speed Setting signal FR2 Second feeding speed setting circuit FR3 Third feeding speed setting circuit Fw Feeding speed IAV Current smoothing circuit Iav Welding current smoothing signal ID Current detection circuit Id Current detection signal IR Current setting circuit Ir Current setting signal Iw Welding current Lw Feeding chip-base material distance PM Power supply main circuit SD Short circuit discrimination circuit Sd Short circuit discrimination signal Sf Positive feed side shift amount SFR Positive feed side system Amount setting circuit Sfr forward side shift amount setting signal Tar arc period reverse period Tas arc period forward period Tf period TFR period setting circuit Tfr period setting signal Trd reverse direction deceleration period TRDR reverse direction deceleration period setting circuit Trdr reverse direction deceleration Period setting signal Trp Reverse feed peak period Tru Reverse feed acceleration period TRUR Reverse feed acceleration period setting circuit Trur Reverse feed acceleration period set signal Tsd Forward feed deceleration period TSDR Forward feed deceleration period setting circuit Tsdr Forward feed deceleration period setting signal Tsp Forward feed peak Period Tsu Positive feed acceleration period TSUR Positive feed acceleration period setting circuit Tsur Positive feed 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 Feed motor Wrp Reverse feed Peak value WRR Reverse transmission amplitude setting circuit Wrr Reverse transmission amplitude setting signal Wsp Positive transmission peak value WSR Positive transmission amplitude setting circuit Wsr Positive transmission Setting signal

Claims (5)

In the arc welding control method of alternately switching the feeding speed of the welding wire between the forward feeding period and the reverse feeding period, repeating the shorting period and the arcing period, and applying welding current for welding,
A smooth value of the welding current is detected, and feedback control of the waveform parameter of the feeding speed is performed so that the welding current smooth value is equal to a predetermined current setting value.
Arc welding control method characterized in that The waveform parameter is amplitude and / or forward shift amount,
The method of controlling arc welding according to claim 1, wherein The waveform parameter is at least one of a forward acceleration period, a forward deceleration period, a reverse acceleration period, a reverse acceleration period, a forward amplitude or a reverse amplitude.
The method of controlling arc welding according to claim 1, wherein The feedback control is performed only when the current setting value is equal to or more than a predetermined reference current value.
The arc welding control method according to any one of claims 1 to 3, characterized in that: The feedback controlled waveform parameter changes in synchronization with a specific timing during the short circuit period,
The arc welding control method according to any one of claims 1 to 3, characterized in that:

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