WO2016027639A1 - Arc welding control method - Google Patents

Abstract

Provided is an arc welding control method that performs welding by alternately switching feed rate (Fw) for welding wire (1) between a forward feed period (Tas) and a reverse feed period (Tar), repeating a short period and an arc period, and applying a welding current (Iw), wherein a smoothed value for the welding current (Iw) is detected and waveform parameters for the feed rate (Fw) is feedback controlled such that this smoothed value for welding current and a predetermined current setting value are the same. Thereby, it is possible to maintain a smoothed value for the welding current as a constant even with fluctuations in the distance between a power feed tip and base material, and make penetration depth uniform.

Description

Arc welding control method

The present invention relates to an arc welding control method in which a welding wire feeding speed is alternately switched between a normal feeding period and a reverse feeding period, a short circuit period and an arc period are repeated, and welding is performed by energizing a welding current.

In general consumable electrode type arc welding, a welding wire as a 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 the consumable electrode type arc welding, the welding wire and the base material are often in a welding state in which a short circuit period and an arc period are alternately repeated.

In order to further improve the welding quality, there has been proposed a method in which welding is performed by periodically repeating the forward and reverse feeding of the welding wire. In invention of patent document 1, it is set as the average value of the feeding speed according to the welding current setting value, and the frequency and amplitude of the forward feed and reverse feeding of the welding wire are values according to the welding current setting value. In the welding method that repeats forward and reverse feeding of the welding wire, the repetition cycle of short-circuiting and arcing, which was impossible with the conventional technology of constant-speed feeding, can be set to a desired value. It is possible to improve the welding quality such as reducing the number of beads and improving the bead appearance.

In the invention of Patent Document 2, the welding wire is fed forward, and the feeding speed is controlled by feedback control of the welding wire feeding speed so that the welding current is equal to a predetermined current set value. In normal consumable electrode arc welding, the feeding speed 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 when the distance between the power supply tip and the base material changes. Since the penetration depth of the base material is substantially proportional to the welding current value, the penetration depth becomes uniform when the welding current value becomes constant. In normal arc welding, welding is performed with a constant distance between the power supply tip and the base material. However, in the case of deep groove welding, multi-layer welding, etc., it may be difficult to maintain a constant distance between the power supply tip and the base material due to problems such as interference between the welding torch and the base material. . Thus, in the welding in which the distance between the power supply tip and the base material varies, the invention of Patent Document 2 is one of important welding qualities because the welding current value is kept constant by variably controlling the feeding speed. It is possible to make uniform by suppressing fluctuations in the penetration depth.

Japanese Patent No. 52012266 Japanese Unexamined Patent Publication No. 7-51854

In the present invention, in welding for alternately switching between a forward feed period and a reverse feed period of the feeding speed, an arc welding control method capable of making the penetration depth uniform even if the distance between the power feed tip and the base material varies. The purpose is to provide.

In order to solve the above-described problem, the arc welding control method of the present invention includes:
In the arc welding control method in which the welding wire feeding speed is alternately switched between the normal feeding period and the reverse feeding period, the short circuit period and the arc period are repeated, and welding is performed by energizing the welding current.
Detecting a smoothing value of the welding current, and feedback-controlling the waveform parameter of the feeding speed so that the welding current smoothing value is equal to a predetermined current setting value;
It is characterized by that.

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

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

The arc welding control method of the present invention performs the feedback control only when the current set value is equal to or greater than a predetermined reference current value.
It is characterized by that.

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 that.

According to the present invention, the welding current smoothing value can be kept constant even when the distance between the power feed tip and the base material fluctuates in welding in which the feed speed is alternately switched between the forward feed period and the reverse feed period. The penetration depth can be made uniform.

It is a block diagram of the welding power supply for implementing the arc welding control method which concerns on Embodiment 1 of this invention. It is a timing chart of each signal in the welding power supply of FIG. 1 which shows the arc welding control method which concerns on Embodiment 1 of this invention. 2 is a timing chart of each signal in the welding power source of FIG. 1 illustrating the operation of variable feed speed control in the arc welding control method according to Embodiment 1 of the present invention. It is a block diagram of the welding power supply for implementing the arc welding control method which concerns on Embodiment 2 of this invention. It is a block diagram of the welding power supply for implementing the arc welding control method which concerns on Embodiment 3 of this invention. It is a timing chart of each signal in the welding power source of FIG. 5 which shows the arc welding control method which concerns on Embodiment 3 of this invention. It is a block diagram of the welding power supply for implementing the arc welding control method which concerns on Embodiment 4 of this invention. It is a timing chart of each signal in the welding power supply of FIG. 7 which shows the arc welding control method which concerns on Embodiment 4 of this invention. FIG. 9 is a timing chart of each signal in the welding power source of FIG. 7 illustrating the operation of variable feed speed control in the arc welding control method according to Embodiment 4 of the present invention.

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

[Embodiment 1]
In the invention of the first embodiment, feedback control is performed on the amplitude and / or the forward feed side shift amount, which are waveform parameters of the feeding speed, so that the smoothing value of the welding current is equal to the preset current setting value. is there.

FIG. 1 is a block diagram of a welding power source for carrying out the arc welding control method according to Embodiment 1 of the present invention. Hereinafter, each block will be described with reference to FIG.

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

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

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

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

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

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

The drive circuit DV receives the voltage error amplification signal 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 power supply main circuit PM. To do.

The current detection circuit ID detects the 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 smoothing signal Iav. This smoothing is performed using a smoothing circuit including a resistor and a capacitor, a low-pass filter, and the like. When a low-pass filter is used, the smoothing time constant can be set by setting a cut-off frequency (about 1 to 10 Hz).

The current setting circuit IR outputs a predetermined current setting signal Ir that becomes a target current value in the feed speed variable control. The feeding error amplification circuit EF amplifies an error between the current setting signal Ir (+) and the welding current smoothing signal Iav (−), and outputs a feeding error amplification signal Ef.

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

The amplitude setting circuit WFR receives the above feed error amplification signal Ef, 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 smoothing signal Iav becomes equal to the value of the current setting signal Ir, and changes every time during welding.

The forward feed shift amount setting circuit SFR receives the feed error amplification signal Ef, integrates the feed error amplification signal Ef during welding, and outputs a forward feed shift amount setting 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 forward 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 changes every time during welding.

The feed speed setting circuit FR receives the period setting signal Tfr, the amplitude setting signal Wfr, and the normal transmission side shift amount setting signal Sfr as input, and is determined by the period and amplitude setting signal Wfr determined by the period setting signal Tfr. A feed speed pattern obtained by shifting the sine wave formed from the amplitude by the forward feed side shift amount determined by the forward feed side shift amount setting signal Sfr is output as the 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.

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

FIG. 2 is a timing chart of each signal in the welding power source of FIG. 1 showing the arc welding control method according to Embodiment 1 of the present invention. FIG. 4A shows the time change of the feeding speed Fw, FIG. 3B shows the time change of the welding current Iw, and FIG. 4C shows the time change of the welding voltage Vw. Hereinafter, a description will be given with reference to FIG.

As shown in FIG. 5A, the feed speed Fw is a forward feed period above 0 and a reverse feed period below. Forward feeding is feeding in the direction in which the welding wire is brought closer to the base material, and reverse feeding is feeding in a direction away from the base material. The feeding speed Fw changes in a sine wave shape and has a waveform shifted to the forward feeding side. For this reason, the average value of the feeding speed Fw is a positive value, and the welding wire is fed forward 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. 5A, the feeding speed Fw is 0 at time t1, the period from time t1 to t2 is the forward acceleration period, the maximum value of forward feeding at time t2, and the time t2 to The period of t3 is the forward deceleration period, becomes 0 at time t3, the period of time t3 to t4 is the reverse acceleration period, becomes the maximum value of reverse transmission at time t4, and the period of time t4 to t5 is the reverse deceleration period It becomes. The period from time t5 to t6 again becomes the normal feed acceleration period, and the period from time t6 to t7 again becomes the normal feed deceleration period. Therefore, the feed speed Fw is determined by the period Tf (ms) from time t1 to t5, the amplitude Wf (m / min) which is the difference between the maximum value of forward feed at time t2 and the maximum value of reverse feed at time t4, It repeats with the feeding speed pattern of sending side shift amount Sf (m / min). 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 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 forward feed side shift amount Sf is feedback-controlled by the feed error amplification circuit EF and the forward feed side 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 The period Tf is set to about 8 to 20 ms, the amplitude Wf changes in the range of about 30 to 100 m / min, and the normal-feed side shift amount Sf changes in the range of about 3 to 20 m / min.

短 絡 Short-circuiting between the welding wire and the base material often occurs before and after the maximum feed value at time t2. In the figure, the case occurs at time t21 during the forward feed deceleration period after the forward feed maximum value. When a short circuit occurs at time t21, the welding voltage Vw rapidly decreases to a short circuit voltage value of several V as shown in FIG. 10C, and the welding current Iw gradually increases as shown in FIG.

As shown in FIG. 4A, the feeding speed Fw is in the reverse feed period from time t3, so the welding wire is fed backward. The short circuit is released by this reverse feed, and the arc is regenerated at time t31. The reoccurrence of the arc often occurs before and after the maximum reverse feed value at time t4. In the figure, the case occurs at time t31 during the reverse acceleration period before the reverse maximum value. Therefore, the period from time t21 to t31 is a short circuit period.

When the arc is regenerated at time t31, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts as shown in FIG. As shown in FIG. 5B, the welding current Iw starts to change from the maximum value during the short circuit period.

During the period from time t31 to t5, as shown in FIG. 5A, the feeding speed Fw is in the reverse feeding state, so that the welding wire is pulled up and the arc length is gradually increased. As the arc length increases, the welding voltage Vw increases and the welding current Iw decreases because constant voltage control is performed by the voltage error amplification circuit EA shown in FIG. Therefore, during the arc period reverse feed period Tar from time t31 to t5, the welding voltage Vw gradually increases as shown in FIG. 3C, and the welding current Iw gradually decreases as shown in FIG. Become.

Then, the next short circuit occurs at time t61 during the normal feed deceleration period from time t6 to t7. However, the short circuit that occurred at time t61 is delayed in the time (phase) from the maximum value of the forward feed than the short circuit that occurred at time t21. Thus, the timing at which a short circuit occurs has some variation. The period from time t31 to t61 is the arc period. During the period from time t5 to time t61, as shown in FIG. 5A, the feed speed Fw is in the forward feed state, so the welding wire is fed forward and the arc length is gradually shortened. When the arc length becomes shorter, the welding voltage Vw becomes smaller and the constant voltage control is performed by the voltage error amplifier circuit EA in FIG. Therefore, during the arc period normal feed period Tas from time t5 to t61, the welding voltage Vw gradually decreases as shown in FIG. 3C, and the welding current Iw gradually increases as shown in FIG. Become.

FIG. 3 is a timing chart of each signal in the welding power source of FIG. 1 showing the operation of the feed speed variable control in the arc welding control method according to the first embodiment of the present invention. FIG. 6A shows the change over time in the distance Lw between the power feed tip and the base material, FIG. 6B shows the change over time in the feed speed average value Fav, and FIG. 6C shows the welding current smoothing signal Iav ( (Solid line) and the time change of the current setting signal Ir (broken line), (D) shows the time change of the amplitude setting signal Wfr, (E) shows the time change of the forward shift amount setting signal Sfr. Show. This figure shows the transient response of each signal when the distance Lw between the power supply tip and the base material becomes longer from L1 (mm) to L2 (mm) at time t1 during welding. The feed speed average value Fav indicates an average value for each cycle of the feed speed Fw shown in FIG. The time scale in the figure is 5 to 10 times longer than that in FIG. Hereinafter, a description will be given with reference to FIG.

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

When the distance between the welding torch and the base material becomes longer at time t1, the distance Lw between the power feed tip and the base material becomes longer from L1 to L2, as shown in FIG. Therefore, as shown in FIG. 6C, 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 an error (feeding error amplification signal Ef>) 0) occurs. In order to maintain the welding current smoothing signal Iav at a constant value by feed speed variable control for returning this error to 0, the amplitude setting signal Wfr shown in FIG. 4D and the forward feed side shown in FIG. Both values of the shift amount setting signal Sfr increase with an inclination from the time t1. In response to this, as shown in FIG. 5B, the feeding speed average value Fav increases with an inclination from the time t1.

As shown in FIG. 5C, the value of the welding current smoothing signal Iav decreases from time t1, reverses from decrease to increase at time t2, returns to the value before time t1 at time t3, and sets the current. The error from the signal Ir is substantially zero. Both values of the amplitude setting signal Wfr shown in FIG. 4D and the forward-side shift amount setting signal Sfr shown in FIG. 4E gradually increase from time t1, and are larger than the values before time t1 at time t3. Converges to a value. In response to this, the feed speed average value Fav gradually becomes faster from time t1 and converges to a value faster than the value before time t1 at time t3, as shown in FIG.

When the distance Lw between the power feed tip and the base material changes in the direction of shortening, the value of the welding current smoothing signal Iav once increases and then returns to the original value. Both values of the amplitude setting signal Wfr and the forward feed side shift amount setting signal Sfr converge to a value smaller than the value before the change, and the feed speed average value Fav converges to a value slower than the value before the change. The transition period from 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 forward feed side shift is set so that the welding current smoothing value and the predetermined current setting value are equal. Feedback control the amount. As a result, in this embodiment, the welding current smoothing value is kept constant even when the distance between the power supply tip and the base material fluctuates in welding in which the forward feed period and the reverse feed period of the feeding speed are alternately switched. Therefore, the penetration depth can be made uniform. At this time, it is desirable to feedback control both the amplitude of the feeding speed and the forward feed side shift amount. This is because the stability of the welding state is improved as compared with the case where only one is feedback-controlled.

[Embodiment 2]
The invention of the second embodiment performs feedback control (feed speed variable control) only when the current set value is equal to or greater than a predetermined reference current value.

FIG. 4 is a block diagram of a welding power source for carrying out the arc welding control method according to the 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. In the figure, 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.

The second feed error amplifier 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 a feed error amplification signal Ef is output, and when the value of the current setting signal Ir is less than the reference current value, a feed error amplification signal Ef that is 0 is output. Thereby, only when the value of the current setting signal Ir is equal to or greater than the reference current value, feedback control of the amplitude setting signal Wfr and the forward-feed-side shift amount setting signal Sfr is performed. 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 set value (current set signal Ir) is equal to or greater than a predetermined reference current value. If the feed speed variable control is performed when the current set value is less than the reference current value, the welding state may become unstable. Therefore, the feed speed variable control is prohibited. Further, when the current set value is less than the reference current value, if the distance between the power supply tip and the base material is changed, the welding state becomes unstable. Therefore, welding is performed without changing.

[Embodiment 3]
In the invention of the third embodiment, the feedback-controlled amplitude and / or forward-feed side shift amount changes in synchronization with a specific timing during the short-circuit period. In the first embodiment, the cycle of the feeding speed and / or the shift amount on the normal feeding side changes asynchronously every moment at an arbitrary timing of the feeding speed by feedback control. On the other hand, in the third embodiment, the period and / or the forward-feed-side 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 carrying out the arc welding control method according to Embodiment 3 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 adding a voltage detection circuit VD and a short circuit determination circuit SD to FIG. 1 and replacing the feed speed setting circuit FR of FIG. 1 with a second feed speed 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 a voltage detection signal Vd. The short-circuit determination circuit SD receives the voltage detection signal Vd as described above, and when this value is less than a predetermined short-circuit determination value (about 10 V), it determines that the short-circuit period is in effect and becomes a High level. A short circuit determination signal Sd which is determined to be in the arc period and becomes Low level is output.

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 normal shift side shift amount setting signal Sfr as inputs, and the cycle setting signal Tfr, The respective values of the amplitude setting signal Wfr and the normal transmission side shift amount setting signal Sfr are read in synchronization with the timing at which the short circuit determination 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 feed speed pattern obtained by shifting the sine wave formed by the amplitude determined by the forward feed side shift amount setting signal Sfr by the forward feed side shift amount setting signal Sfr is output as the feed speed setting signal Fr. 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 includes a timing at which a short circuit occurs, a timing after a predetermined period after the short circuit has occurred, a timing at which the feed speed setting signal Fr changes from forward to reverse during the short circuit period, and the like.

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. FIG. 4A shows the time change of the feeding speed Fw, FIG. 3B shows the time change of the welding current Iw, and FIG. 4C shows the time change of the 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 second feed speed setting circuit FR2 of FIG. 5 synchronizes the values of the cycle setting signal Tfr, the amplitude setting signal Wfr, and the forward feed shift amount setting signal Sfr in synchronization with the short circuit occurrence timing. 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 feed side shift amount setting signal Sfr have been changed by feedback control, at time t21, as shown in FIG. 5A, the amplitude Wf of the feed speed Fw and the forward feed side shift amount. Sf is increased. The same applies to time t61 when the next short circuit occurs. In this way, the amplitude Wf and the forward feed 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, such as a short-circuit occurrence timing, a timing after a predetermined period from the occurrence of the short-circuit, or a timing (time t3) when changing from normal feed to reverse feed during the short-circuit period. is there.

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

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 in FIG. 5 showing the operation of the feed speed variable control is the same as that in FIG. Absent. Although the third embodiment is based on the first embodiment, the same applies to the second embodiment.

According to the above-described third embodiment, the amplitude and / or the forward shift amount changes in synchronization with the specific timing during the short circuit period. Thereby, in this Embodiment, since the waveform parameter of feeding speed is updated during a short circuit period, a welding state can be maintained stably.

In Embodiments 1 to 3 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 parameter value that is not changed is set to a predetermined value.

[Embodiment 4]
In the invention of the fourth embodiment, the forward feed acceleration period, the forward feed deceleration period, the reverse feed acceleration period, which are waveform parameters of the feed speed, so that the smoothing value of the welding current is equal to the predetermined current set value, Feedback control is performed for at least one of the reverse feed deceleration period, the forward feed amplitude, and the reverse feed amplitude. Then, the waveform parameter that is feedback-controlled changes in synchronization with the specific timing during the short circuit period.

FIG. 7 is a block diagram of a welding power source for carrying out the arc welding control method according to the fourth embodiment of the present invention. This figure corresponds to FIG. 5 described above, and the same reference numerals are given to the same blocks, and description thereof will not be repeated. In the figure, the period setting circuit TFR, the amplitude setting circuit WFR, and the forward-feed-side shift amount setting circuit SFR in FIG. 5 are deleted. Then, the same second feed error amplifier circuit EF2 as FIG. 4 is added, and the forward feed acceleration period setting circuit TSUR, the forward feed deceleration period setting circuit TSDR, the reverse feed acceleration period setting circuit TRUR, and the reverse feed deceleration period setting circuit TRDR. A forward feed amplitude setting circuit WSR and a reverse feed amplitude setting circuit WRR are added. Further, the second feed speed setting circuit FR2 in FIG. 5 is replaced with a third feed speed setting circuit FR3. Hereinafter, these blocks will be described with reference to FIG.

The second feed error amplifier 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 a feed error amplification signal Ef is output, and when the value of the current setting signal Ir is less than the reference current value, a feed error amplification signal Ef that is 0 is output. 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.

The forward feed acceleration period setting circuit TSUR receives the feed error amplification signal Ef, integrates the feed error amplification signal Ef during welding, and outputs a forward 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 normal feed 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 changes every time during welding.

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

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

The reverse feed deceleration period setting circuit TRDR receives the feed error amplification signal Ef, integrates the feed error amplification 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 smoothing signal Iav becomes equal to the value of the current setting signal Ir, and changes every time during welding.

The forward feed amplitude setting circuit WSR outputs a predetermined forward 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 includes the forward feed acceleration period setting signal Tsur, the forward feed deceleration period setting signal Tsdr, the reverse feed acceleration period setting signal Trur, the reverse feed deceleration period setting signal Trdr, With the forward feed amplitude setting signal Wsr, the reverse feed amplitude setting signal Wrr and the short circuit determination signal Sd as inputs, the feed speed pattern generated by the following processing is output as the 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. Further, the waveform parameters (Tsur, Tsdr, Trur, Trdr, Wsr, and Wrr) of the feeding speed are updated in synchronization with a specific timing during the short circuit period. The specific timing includes a timing at which a short circuit occurs, a timing after a predetermined period after the short circuit has occurred, a timing at which the feed speed setting signal Fr changes from forward to reverse during the short circuit period, and the like.
1) A feed speed setting signal Fr that linearly accelerates from 0 to a positive feed peak value Wsp determined by a forward feed amplitude setting signal Wsr during a forward feed acceleration period Tsu determined by a forward feed acceleration period setting signal Tsur. Output.
2) Subsequently, during the forward feed peak period Tsp, the feed speed setting signal Fr for maintaining the forward feed peak value Wsp is output.
3) When the short circuit determination signal Sd changes from the Low level (arc period) to the High level (short circuit period), the waveform parameter of the feeding speed is read and updated. At the same time, the process shifts to a normal feed deceleration period Tsd determined by the normal feed deceleration period setting signal Tsdr, and a feed speed setting signal Fr that linearly decelerates from the normal feed peak value Wsp to 0 is output.
4) Subsequently, during the reverse feed acceleration period Tru determined by the reverse feed acceleration period setting signal Trur, the feed speed setting for linearly accelerating from 0 to the negative reverse feed peak value Wrp determined by the reverse feed amplitude setting signal Wrr. The signal Fr is output.
5) Subsequently, during the reverse feed peak period Trp, the feed speed setting signal Fr that maintains the reverse feed peak value Wrp is output.
6) When the short circuit determination signal Sd changes from the High level (short circuit period) to the Low level (arc period), it shifts to the reverse feed deceleration period Trd determined by the reverse feed deceleration period setting signal Trdr, and from the reverse feed peak value Wrp. A feed speed setting signal Fr that linearly decelerates to 0 is output.
7) By repeating the above 1) to 6), a feed rate setting signal Fr of a feed pattern that changes into a positive and negative trapezoidal waveform 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. (A) shows the time change of the feeding speed Fw, (B) shows the time change of the welding current Iw, (C) shows the time change of the welding voltage Vw, (D) ) Shows the time change of the short circuit determination signal Sd. Hereinafter, the operation of each signal will be described with reference to FIG.

The feed speed Fw shown in FIG. 5A is controlled to the value of the feed speed setting signal Fr output from the third feed speed setting circuit FR3 in FIG. The feed speed Fw includes a forward feed acceleration period Tsu that is feedback-controlled by the forward feed acceleration period setting signal Tsur in FIG. 7, a forward feed peak period Tsp that continues until a short circuit occurs, and a forward feed deceleration period setting signal Tsdr in FIG. Is determined by the forward feed deceleration period Tsd determined by, the reverse feed acceleration period Tru determined by the reverse feed acceleration period setting signal Trur in FIG. 7, the reverse feed peak period Trp that continues until an arc occurs, and the reverse feed deceleration period setting signal Trdr in FIG. It is formed from a reverse feed deceleration period Trd that is feedback controlled. Further, the forward feed peak value Wsp is determined by the forward feed amplitude setting signal Wsr in FIG. 7, and the reverse feed peak value Wrp is determined by the reverse feed 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 shape. As in the second embodiment, the 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 higher than the reference current value. Furthermore, the waveform parameter of the feed speed Fw that is feedback-controlled changes in synchronization with the specific timing of the short circuit period.

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

When the reverse acceleration period Tru ends at time t2, the feed speed Fw enters the reverse peak period Trp and becomes the reverse peak value Wrp as shown in FIG. Even during this period, the short-circuit period continues.

When an arc is generated at time t3, the short circuit determination signal Sd is changed to a low level (arc period) as shown in FIG. In response to this, a transition is made to a predetermined reverse feed deceleration period Trd at times t3 to t4, and the feed speed Fw is reduced from the reverse feed peak value Wrp to 0 as shown in FIG. . At the same time, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts as shown in FIG. 3C, and the welding current Iw gradually decreases during the arc period as shown in FIG.

[Operation in the forward feed period from time t4 to t7]
When the reverse feed deceleration period Trd ends at time t4, the routine proceeds to a predetermined forward feed acceleration period Tsu at times t4 to t5. During the normal feed acceleration period Tsu, the feed speed Fw is accelerated from 0 to the normal feed peak value Wsp as shown in FIG. During this period, the arc period continues.

When the normal feed acceleration period Tsu ends at time t5, the feed speed Fw enters the normal feed peak period Tsp as shown in FIG. The arc period continues during this period.

When a short circuit occurs at time t6, as shown in FIG. 4D, the short circuit determination signal Sd changes to a high level (short circuit period), and the forward feed acceleration period setting signal Tsur and the reverse feed deceleration period that are feedback-controlled. The setting signal Trdr is read and updated in synchronization with the occurrence of a short circuit. In response to this, a transition is made to a predetermined forward feed deceleration period Tsd at times t6 to t7, and the feed speed Fw is reduced from the forward feed peak value Wsp to 0 as shown in FIG. . At the same time, the welding voltage Vw rapidly decreases to a short-circuit voltage value of several V as shown in FIG. 5C, and the welding current Iw gradually increases during the short-circuit period as shown in FIG.

FIG. 9 is a timing chart of each signal in the welding power source of FIG. 7 illustrating the operation of the feed speed variable control in the arc welding control method according to the fourth embodiment of the present invention. FIG. 6A shows the change over time in the distance Lw between the power feed tip and the base material, FIG. 6B shows the change over time in the feed speed average value Fav, and FIG. 6C shows the welding current smoothing signal Iav ( (Solid line) and the time change of the current setting signal Ir (broken line) are shown, (D) shows the time change of the forward feed acceleration period setting signal Tsur, and (E) is the time of the reverse feed deceleration period setting signal Trdr. Showing change. This figure shows the transient response of each signal when the distance Lw between the power supply tip and the base material becomes longer from L1 (mm) to L2 (mm) at time t1 during welding. The feeding speed average value Fav indicates an average value for each cycle of the feeding speed Fw shown in FIG. The time scale in the figure is 5 to 10 times longer than that in FIG. Hereinafter, a description will be given with reference to FIG.

During the period before time t1, as shown in FIG. 5A, the distance Lw between the power feed tip and the base material is in a constant state of L1 (mm), so the welding current indicated by the solid line in FIG. The value of the smooth signal Iav is equal to the value of the current setting signal Ir indicated by a broken line. For this reason, each value of the forward feed acceleration period setting signal Tsur shown in FIG. 4D and the reverse feed deceleration period setting signal Trdr shown in FIG. Thus, the feeding speed average value Fav is in a substantially constant state.

When the distance between the welding torch and the base material becomes longer at time t1, the distance Lw between the power feed tip and the base material becomes longer from L1 to L2, as shown in FIG. Therefore, as shown in FIG. 6C, 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 an error (feeding error amplification signal Ef>) 0) occurs. In order to maintain the value of the welding current smoothing signal Iav at a constant value by the feed speed variable control for returning this error to 0, the normal feed acceleration period setting signal Tsur shown in FIG. Further, the reverse feed deceleration period setting signal Trdr shown in FIG. 5E decreases from the time t1 with an inclination. In response to this, as shown in FIG. 5B, the feeding speed average value Fav increases with an inclination from the time t1.

As shown in FIG. 5C, the value of the welding current smoothing signal Iav decreases from time t1, reverses from decrease to increase at time t2, returns to the value before time t1 at time t3, and sets the current. The error from the signal Ir is substantially zero. The forward acceleration period setting signal Tsur shown in FIG. 4D gradually increases from time t1, and converges to a value larger than the value before time t1 at time t3. Further, the reverse transmission deceleration period setting signal Trdr shown in FIG. 9E 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 becomes faster from time t1 and converges to a value faster than the value before time t1 at time t3, as shown in FIG.

When the distance Lw between the power feed tip and the base material changes in the direction of shortening, the value of the welding current smoothing 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 the change, the reverse feed deceleration period setting signal Trdr converges to a larger value than before the change, and the feed speed average value Fav is the value before the change. Converge to slower values. The transition period from 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 parameter of the feed speed Fw to be feedback-controlled is the forward feed acceleration period Tsu and the reverse feed deceleration period Trd is illustrated. The waveform parameters of the feed speed Fw to be feedback controlled are the forward feed acceleration period Tsu, the forward feed deceleration period Tsd, the reverse feed acceleration period Tru, the reverse feed deceleration period Trd, the forward feed amplitude (forward feed peak value Wsp) or the reverse feed. It may be at least one of amplitudes (reverse peak value Wrp).

Of the waveform parameters of the feed speed Fw, the feedback state is controlled 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, so that the welding state is more stabilized. can do.

According to the fourth embodiment described above, the smoothing value of the welding current is detected, and the forward feed acceleration period, the forward feed deceleration period, and the reverse feed are set so that the welding current smooth value is equal to the predetermined current set value. Feedback control is performed for at least one of the acceleration period, the reverse feed deceleration period, the forward feed amplitude, or the reverse feed amplitude. As a result, in this embodiment, the welding current smoothing value is kept constant even when the distance between the power supply tip and the base material fluctuates in welding in which the forward feed period and the reverse feed period of the feeding speed are alternately switched. Therefore, the penetration depth can be made uniform.

According to the present invention, the welding current smoothing value can be kept constant even when the distance between the power feed tip and the base material fluctuates in welding in which the feed speed is alternately switched between the forward feed period and the reverse feed period. The penetration depth can be made uniform.

As mentioned above, although this invention was demonstrated by specific embodiment, this invention is not limited to this embodiment, A various change is possible in the range which does not deviate from the technical idea of the disclosed invention.
This application is based on a Japanese patent application filed on August 18, 2014 (Japanese Patent Application No. 2014-165777) and a Japanese patent application filed on January 20, 2015 (Japanese Patent Application No. 2015-008198). Captured here.

DESCRIPTION OF SYMBOLS 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 Feeding error amplification circuit Ef Feeding error amplification signal EF2 Second feeding error amplification circuit ER Output voltage setting circuit Er Output voltage setting signal Fav Feeding speed average value FC Feeding control circuit Fc Feeding control signal FR Feeding speed setting circuit Fr Feeding speed Setting signal FR2 Second feed speed setting circuit FR3 Third feed speed setting circuit Fw Feed 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 Power supply chip / base material distance PM Power supply main circuit SD Short circuit detection circuit d Short-circuit determination signal Sf Forward feed shift amount SFR Forward feed shift amount setting circuit Sfr Forward feed shift amount setting signal Tar Arc period reverse feed period Tas Arc period forward feed period Tf Period TFR Period setting circuit Tfr Period setting signal Trd Reverse Reverse feed deceleration period TRDR Reverse feed deceleration period setting signal Trdr Reverse feed deceleration period setting signal Trp Reverse feed peak period Tru Reverse feed acceleration period setting circuit Trur Reverse feed acceleration period setting 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 Su Forward feed acceleration period TSUR Forward feed acceleration period setting circuit Tsur Forward 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 WRR backhaul amplitude setting circuit Wrr backhaul amplitude setting signal Wsp positive feed peak value WSR positive feed amplitude setting circuit Wsr positive feed amplitude setting signal

Claims (5)

In the arc welding control method in which the welding wire feeding speed is alternately switched between the normal feeding period and the reverse feeding period, the short circuit period and the arc period are repeated, and welding is performed by energizing the welding current.
Detecting a smoothing value of the welding current, and feedback-controlling the waveform parameter of the feeding speed so that the welding current smoothing value is equal to a predetermined current setting value;
An arc welding control method characterized by the above. The waveform parameter is an amplitude and / or a forward shift amount;
The arc welding control method according to claim 1, wherein: The waveform parameter is at least one of a forward feed acceleration period, a forward feed deceleration period, a reverse feed acceleration period, a reverse feed deceleration period, a forward feed amplitude, or a reverse feed amplitude.
The arc welding control method according to claim 1, wherein: The feedback control is performed only when the current set value is equal to or greater than a predetermined reference current value.
The arc welding control method according to any one of claims 1 to 3, wherein: 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, wherein:

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