JPWO2016117228A1 - Arc welding control method - Google Patents

Abstract

In an arc welding control method for performing welding by generating a short circuit period and an arc period by performing forward / reverse feed control for alternately switching the feed speed Fw of the welding wire between a forward feed period and a reverse feed period, a welding end command At the time t14 when St is input and the transition from the short-circuit period to the arc period occurs, the feed speed Fw is switched from the normal / reverse feed control to the reverse feed control, and the welding is finished. Thereby, during the anti-stick period after switching to the reverse feed control, the welding wire is controlled to be fed backward, so that the arc state continues and a stable welding state is obtained.

Description

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

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

  In order to further improve the welding quality, there has been proposed a method in which welding is performed by periodically repeating forward feeding and backward feeding of a welding wire (see, for example, Patent Documents 1 and 2).

  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 the reverse feeding of the welding wire are values according to the welding current setting value.

  In the invention of Patent Document 2, the wire feed speed is set to a predetermined constant speed during steady welding, and from the time when the end of welding is instructed, the wire feed speed is changed from normal feed and reverse feed from the predetermined constant speed. Switch to repeated feeding.

Japanese Patent No. 52012266 WO2013 / 136663 Publication

  As described above, in the prior art, stable welding is performed by performing forward / reverse feed control in which the feed speed is alternately switched between a predetermined forward feed period and a predetermined reverse feed period during the steady welding period. be able to. However, in the prior art, when welding is finished, there is a problem that the welding state becomes unstable during a so-called anti-stick period which is a transition period from the forward / reverse feed control to the stop of feed.

  Accordingly, an object of the present invention is to provide an arc welding control method capable of stabilizing the welding state during the anti-stick period in welding in which the forward feed period and the reverse feed period of the feeding speed are alternately switched. To do.

  In order to solve the above-described problem, the arc welding control method of the present invention performs forward / reverse feed control for alternately switching the welding wire feed speed between the forward feed period and the reverse feed period, and the short circuit period and the arc. In the arc welding control method of generating a period and welding, when a welding end command is input, the feed speed is switched from the forward / reverse feed control to the reverse feed control, and the welding is finished. To do.

  The arc welding control method of the present invention is characterized in that switching to the reverse feed control is performed after the short-circuit period is shifted to the arc period after the welding end command is input.

  The arc welding control method of the present invention is characterized in that when the reverse feed control is continued for a predetermined period, the feed is stopped and the reverse feed control is terminated.

  The arc welding control method of the present invention is characterized in that when the welding current is not energized during the reverse feed control, the feed is stopped and the reverse feed control is terminated.

  The arc welding control method of the present invention is characterized in that the end point of the reverse feed control and the point of time when the output of the welding voltage is stopped are set independently.

  The arc welding control method of the present invention is characterized in that the output of the welding voltage is stopped when the reverse feed control is completed.

  The arc welding control method of the present invention is characterized in that constant current control is performed on the welding power source after switching to the reverse feed control.

  The arc welding control method of the present invention is characterized in that the feed speed is set to a constant speed during the reverse feed control.

  The arc welding control method of the present invention is characterized in that the feed speed is set to be gradually reduced during the reverse feed control.

  According to the present invention, during the anti-stick period after switching to the reverse feed control, since the welding wire is controlled to reverse feed, the arc state continues and a stable welding state is achieved. For this reason, in this invention, since the distance of a welding wire front-end | tip and a bead becomes an appropriate distance at the time of completion | finish of welding, it can prevent that a welding wire welds with a bead. Furthermore, in the present invention, the size of the welding wire tip grain is optimized, and the next arc start property can be improved.

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 at the time of completion | finish of welding in the welding power supply of FIG. 1 which shows the arc welding control method which concerns on Embodiment 1 of this invention. It is a 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 block diagram of the welding power supply for implementing the arc welding control method which concerns on Embodiment 4 of this invention.

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

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

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

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

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

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

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

  The welding start circuit ST outputs a welding start signal St that is at a high level when a welding start command is issued and that is at a low level when a welding end command is issued. The welding start circuit ST corresponds to a start switch of the welding torch 4, a PLC that controls the welding process, a robot control device, and the like.

  The reverse feed control period determination circuit STK receives the welding start signal St and the short circuit determination signal Sd, and after the welding start signal St changes from High level to Low level (welding end command), the short circuit determination signal Sd. Is set to the high level when the signal level changes from the high level to the low level (arc), and then the reverse control period signal Stk which is reset to the low level when the predetermined reverse control period Tk has passed.

  The anti-stick voltage output period discriminating circuit STB receives the above-mentioned reverse feed control period signal Stk and is set to High level when the reverse feed control period signal Stk changes to High level, and then outputs a predetermined anti-stick voltage output. When the period Tb elapses, the anti-stick voltage output period signal Stb that is reset to the low level is output.

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

  The steady welding period feed rate setting circuit FCR receives the average feed rate setting signal Far, the cycle setting signal Tfr, and the amplitude setting signal Wfr, and receives the amplitude Wf and cycle setting signal determined by the amplitude setting signal Wfr. A steady welding period feed speed setting signal Fcr is output that has a waveform obtained by shifting a predetermined trapezoidal wave that changes to a positive and negative symmetrical shape with a period Tf determined by Tfr to the forward feed side by the value of the average feed speed setting signal Far. . The steady welding period feed speed setting signal Fcr will be described in detail with reference to FIG.

  The reverse feed speed setting circuit FKR outputs a predetermined reverse feed speed setting signal Fkr. Since Fkr is a reverse feed, it becomes a negative value.

  The feed speed setting circuit FR receives the above-described steady welding period feed speed setting signal Fcr, the above reverse feed speed setting signal Fkr, and the above reverse feed control period signal Stk, and receives the reverse feed control period signal Stk. When the level is Low, the steady welding period feed rate setting signal Fcr is output as the feed rate setting signal Fr. When Stk = High level, the reverse feed rate setting signal Fkr is output as the feed rate setting signal Fr. .

  The feed control circuit FC receives the welding start signal St, the reverse feed control period signal Stk, and the feed speed setting signal Fr as input, and the welding start signal St changes to a high level (welding start command). 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 is output, and the feed is performed when the reverse feed control period signal Stk changes to the Low level. A feed control signal Fc for stopping the feed is output to the feed motor WM.

  The steady output voltage setting circuit ECR outputs a predetermined steady output voltage setting signal Ecr. The anti-stick output voltage setting circuit EBR outputs a predetermined anti-stick output voltage setting signal Ebr.

  The output voltage setting circuit ER receives the steady output voltage setting signal Ecr, the anti-stick output voltage setting signal Ebr and the anti-stick voltage output period signal Stb as input, and when the anti-stick voltage output period signal Stb is at the low level. The steady output voltage setting signal Ecr is output as the output voltage setting signal Er, and when the Stb = High level, the anti-stick output voltage setting signal Ebr is output as the output voltage setting signal Er.

  The output voltage detection circuit ED detects and smoothes the output voltage E and outputs an output voltage detection signal Ed.

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

  The drive circuit DV receives the voltage error amplification signal Ev, the welding start signal St and the anti-stick voltage output period signal Stb, and the voltage error occurs when the welding start signal St changes to a high level (welding start command). PWM modulation control is performed based on the amplified signal Ev, the drive signal Dv for driving the inverter circuit in the power supply main circuit PM is output, and when the anti-stick voltage output period signal Stb changes to the Low level, the drive signal Dv Stop the output of. That is, the welding power source is activated from the time when the welding start signal changes to the high level to the time when the anti-stick voltage output period signal Stb changes to the low level, and the welding voltage Vw is output.

  FIG. 2 is a timing chart of signals at the end of welding in the welding power source of FIG. 1, showing the arc welding control method according to the first embodiment of the present invention. (A) shows the time change of the welding start signal St, (B) shows the time change of the feeding speed Fw, (C) shows the time change of the welding current Iw, (D) shows the time change of the welding voltage Vw, (E) shows the time change of the short-circuit determination signal Sd, (F) shows the time change of the reverse feed control period signal Stk, (G) ) Shows the time change of the anti-stick voltage output period signal Stb. Hereinafter, the operation of each signal at the end of welding will be described with reference to FIG.

  As shown in the figure, the period up to time t14 is a steady welding period, and the period from time t14 to t15 is an anti-stick period. The period from time t14 to t15 is the reverse feed control period Tk, and the period from time t14 to t15 is the anti-stick voltage output period Tb. As will be described later, the start times of the anti-stick period, the reverse feed control period Tk, and the anti-stick voltage output period Tb are the same time t14, and at the time t11 when the welding start signal St changes to the Low level (welding end command). Later, it is time t14 when the short-circuit period shifts to the arc period. In addition, although the end points of the reverse feed control period Tk and the anti-stick voltage output period Tb are set independently, the case where the end points are the same time is illustrated in FIG.

  The feed speed Fw shown in FIG. 5B is controlled to the value of the feed speed setting signal Fr output from the feed speed setting circuit FR of FIG. The feed speed setting signal Fr (steady welding period feed speed setting signal Fcr) during the steady welding period is determined in advance to change into a positive / negative symmetrical shape with the amplitude Wf determined by the amplitude setting signal Wfr and the period Tf determined by the period setting signal Tfr. The trapezoidal wave is shifted to the forward feed side by the value of the average feed speed setting signal Far. For this reason, as shown in FIG. 5B, the feed speed Fw during the steady welding period is vertically symmetrical with the average feed speed Fa indicated by the broken line determined by the average feed speed setting signal Far as a reference line. It becomes a trapezoidal wave-shaped feeding speed pattern determined in advance with an amplitude Wf and a period Tf. That is, the amplitude above the reference line and the amplitude below the reference line have the same value, and the period above and below the reference line have the same value.

  Here, when the trapezoidal wave of the feeding speed Fw during the steady welding period is seen with 0 as the reference line, the steady welding period reverse feed period at the times t1 to t5 is set to a predetermined value as shown in FIG. A normal welding period reverse feed acceleration period, a steady welding period reverse feed peak period, a steady welding period reverse feed peak value, and a steady welding period reverse feed deceleration period are formed. The normal welding period of the normal welding period, the normal welding period of the normal feed peak period, the steady welding period of the normal feed peak value, and the steady welding period of the normal feed deceleration period.

[Operation of the steady welding period reverse feed period at times t1 to t5]
As shown in FIG. 5A, the welding start signal St is at a high level (welding start command). As shown in FIG. 5B, the feeding speed Fw enters the steady welding period reverse feed acceleration period from time t1 to t2, and accelerates from 0 to the above-mentioned steady welding period reverse feed peak value. Since the short circuit state continues during this period, the short circuit determination signal Sd is at the high level (short circuit) as shown in FIG.

  When the steady welding period reverse feed acceleration period ends at time t2, the feed speed Fw enters the steady welding period reverse feed peak period at times t2 to t4 as shown in FIG. The peak value is reached. At time t3 during this period, the arc 3 is regenerated by the pinch force generated by reverse feeding and energization of the welding current Iw. In response to this, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts as shown in FIG. 4D, and the short-circuit determination signal Sd is set at the low level (arc) as shown in FIG. ). As shown in FIG. 5C, the welding current Iw gradually decreases during the subsequent arc period.

  When the steady welding period reverse feed peak period ends at time t4, as shown in FIG. 5B, the steady welding period reverse feed deceleration period of time t4 to t5 is entered, and the steady welding period reverse feed peak value is 0. To slow down.

[Operations during normal welding period at time t5 to t9]
As shown in FIG. 5B, the feeding speed Fw enters the normal welding acceleration period during the normal welding period from time t5 to t6, and accelerates from 0 to the normal peak value during the normal welding period. During this period, the arc period remains.

  When the steady welding period forward feed acceleration period ends at time t6, the feed speed Fw enters the regular welding period forward feed peak period at times t6 to t8 as shown in FIG. The peak value is reached. At time t7 during this period, a short circuit occurs due to normal feeding. In response to this, the welding voltage Vw rapidly decreases to a short circuit voltage value of several V as shown in FIG. 4D, and the short circuit determination signal Sd is at a high level (short circuit) as shown in FIG. To change. As shown in FIG. 5C, the welding current Iw gradually increases during the subsequent short-circuit period.

  When the steady welding period forward feed peak period ends at time t8, the steady welding period forward feed deceleration period of time t8 to t9 is entered, as shown in FIG. To slow down.

  The above operation is repeated during the reverse feed period of the steady welding period from time t9 to t10. Therefore, an arc is generated during the reverse peak period of the steady welding period.

  At time t11 during the regular welding period forward feed period from time t10 to t12, the welding start signal St is at a low level (welding end) as shown in FIG. Command). Therefore, the welding start signal St changes to the low level during the arc period. After the welding start signal St changes to the Low level, the steady welding period starts until the time when the welding period first changes from the short-circuit period to the arc period (time t14 in the figure). Therefore, the same operation as described above is repeated during the regular welding period normal feeding period from time t10 to t13. For this reason, a short circuit occurs during the regular welding period positive feed peak period. The timing at which the welding start signal St becomes the Low level is an arbitrary timing of the feed speed Fw, and it is also optional whether it is during the arc period or during the short circuit period.

[Operation during anti-stick period from time t14 to t15]
From time t13, a steady welding period reverse feed period starts, and an arc is generated at time t14 during the steady welding period reverse feed peak period. The anti-stick period starts from this time t14. When an arc is generated at time t14, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts as shown in FIG. In response to this, as shown in FIG. 5E, the short circuit determination signal Sd changes to the low level (arc). In response to this, as shown in FIG. 4F, the reverse control period signal Stk changes to the high level, and returns to the low level at time t15 after the elapse of the predetermined reverse control period Tk. At the same time, as shown in FIG. 5G, the anti-stick voltage output period signal Stb also changes to High level, and returns to Low level after elapse of a predetermined anti-stick voltage output period Tb. When the reverse feed control period signal Stk changes to High level, the feed speed Fw decelerates with a slope to a predetermined reverse feed speed Fk as shown in FIG. This reverse feed speed Fk is set by the reverse feed speed setting signal Fkr of FIG. The period from time t14 to t15 is a predetermined reverse feed control period Tk and a predetermined antistick voltage output period Tb. As described above, since Tk and Tb are set independently, Tk ≠ Tb may be satisfied. As shown in FIG. 5B, the feed speed Fw becomes the reverse feed speed Fk during the reverse feed control period Tk, and becomes zero because the feed is stopped at time t15. As shown in FIG. 4D, the output of the welding voltage Vw is continued during the anti-stick voltage output period Tb and becomes 0 at time t15. The welding power source is controlled at a constant voltage throughout the period, is controlled at a constant voltage based on the steady output voltage setting signal Ecr during the steady welding period, and is controlled at a constant voltage based on the anti-stick output voltage setting signal Ebr during the anti-stick period. Is done. Ebr <Ecr is set.

  As shown in FIG. 5C, the welding current Iw decreases from time t14 and continues the state of several tens of A until time t15 when the anti-stick voltage output period Tb ends. The value of the welding current Iw varies depending on the arc load because the output is controlled at a constant voltage.

  During the anti-stick period from time t14 to t15, the arc period continues, and the welding wire is melted by arc heat while being fed back. Then, when welding is completed at time t15, the reverse feed speed Fk and the reverse feed control period Tk are set so that the distance between the tip of the welding wire and the bead and the size of the welding wire tip grain are appropriate. Is set. Both values are set to appropriate values by experiments according to welding conditions such as the diameter, material, joint shape, and welding posture of the welding wire. For example, the reverse feed speed Fk is set to about −3 to −10 m / min, and the reverse feed control period Tk is set to about 1 to 50 ms. The slope when switching to the reverse feed speed Fk is set to about 0 to 5 ms. When 0, the slope is not provided.

A numerical example of the trapezoidal wave of the feeding speed Fw during the steady welding period is shown below.
A trapezoidal wave with period Tf = 10 ms, amplitude Wf = 60 m / min, average feeding speed Fa = 5 m / min, each half period of inclination period = 1.2 ms, peak period = 2.6 ms, peak value = 30 m / min When set, the trapezoidal wave has a waveform shifted to the forward feed side by the average feed speed Fa = 5 m / min. The average welding current is about 250A. Each waveform parameter in this case is as follows.
Normal welding period reverse feed period = 4.6 ms, steady welding period reverse feed acceleration period = 1.0 ms, steady welding period reverse feed peak period = 2.6 ms, steady welding period reverse feed peak value = −25 m / min, steady welding Period reverse feed deceleration period = 1.0 ms.
Regular welding period forward feed period = 5.4 ms, steady welding period forward feed acceleration period = 1.4 ms, steady welding period forward feed peak period = 2.6 ms, steady welding period forward feed peak value = 35 m / min, steady welding period Normal feed deceleration period = 1.4 ms.

  According to the first embodiment described above, when the welding end command is input, the feed speed is switched from the forward / reverse feed control to the reverse feed control, and the welding is finished. During the anti-stick period, the welding wire is reversely controlled, so that the arc state is continued and a stable welding state is obtained. For this reason, at the end of welding, the distance between the tip of the welding wire and the bead becomes an appropriate distance, so that the welding wire can be prevented from being welded to the bead. Furthermore, the size of the welding wire tip grain is optimized, and the next arc start property can be improved.

  Further, according to the first embodiment described above, switching to the reverse feed control is performed after the transition from the short-circuit period to the arc period after the welding end command is input. Thereby, the transition from the steady welding period to the anti-stick period becomes smooth, and the welding state during the anti-stick period is further stabilized.

[Embodiment 2]
The invention of the second embodiment performs constant current control of the welding power source after switching to reverse feed control. In the invention of the first embodiment, constant voltage control is performed during the anti-stick period after switching to the steady welding period and the reverse feed control. On the other hand, in the invention of Embodiment 2, constant voltage control is performed during the steady welding period, and constant current control is performed during the antistick period.

  FIG. 3 is a block diagram of a welding power source for carrying out the arc welding control method according to the second embodiment. This figure corresponds to FIG. 1 described above, and the same reference numerals are given to the same blocks, and description thereof will not be repeated. In FIG. 1, an anti-stick current setting circuit IBR, a current detection circuit ID, a current error amplifier circuit EI, and a power supply characteristic switching circuit SW are added to FIG. 1, and the drive circuit DV in FIG. 1 is replaced with a second drive circuit DV2. It is. Hereinafter, these blocks will be described with reference to FIG.

  The anti-stick current setting circuit IBR outputs a predetermined anti-stick current setting signal Ibr. The anti-stick current setting signal Ibr is set to about 30 to 100 A, for example. The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id.

  The current error amplification circuit EI amplifies an error between the anti-stick current setting signal Ibr (+) and the current detection signal Id (−) by using the anti-stick current setting signal Ibr and the current detection signal Id as inputs. The current error amplification signal Ei is output. With this circuit, the welding power source is controlled at a constant current during the anti-stick period.

  The power supply characteristic switching circuit SW receives the current error amplification signal Ei, the voltage error amplification signal Ev, and the antistick voltage output period signal Stb, and the antistick voltage output period signal Stb is at a low level (steady welding period). ), The voltage error amplification signal Ev is output as the error amplification signal Ea, and when Stb = High level (anti-stick period), the current error amplification signal Ei is output as the error amplification signal Ea.

  The second drive circuit DV2 receives the error amplification signal Ea, the welding start signal St, and the anti-stick voltage output period signal Stb, and receives an error when the welding start signal St changes to a high level (welding start command). PWM modulation control is performed based on the amplified signal Ea, a drive signal Dv for driving the inverter circuit in the power supply main circuit PM is output, and when the anti-stick voltage output period signal Stb changes to a low level, the drive signal Dv Stop the output of. That is, the welding power source is activated from the time when the welding start signal changes to the High level to the time when the anti-stick voltage output period signal Stb changes to the Low level, and the welding voltage Vw and the welding current Iw are output.

  Since the timing chart of each signal at the end of welding in the welding power source of FIG. 3 showing the arc welding control method according to the second embodiment of the present invention is the same as FIG. 2 described above, description thereof will not be repeated. However, since the constant current control is performed during the anti-stick period after time t14, the welding current Iw shown in FIG. 4C is different in that it has a constant current value determined by the anti-stick current setting signal Ibr.

  According to the second embodiment described above, the constant current control is performed on the welding power source after switching to the reverse feed control. Thereby, since the value of the welding current Iw during the anti-stick period becomes a predetermined value, the amount of heat input to the welding wire during the anti-stick period can be precisely controlled. For this reason, in addition to the effects of the first embodiment, the distance between the welding wire tip and the bead at the end of welding and the size of the welding wire tip grain can be precisely controlled by appropriate values.

[Embodiment 3]
In the invention of the third embodiment, the feed is stopped and the reverse feed control is terminated when the welding current is not energized during the reverse feed control. In the inventions of Embodiments 1 and 2, the reverse feed control period is a predetermined value. On the other hand, in the invention of Embodiment 3, the reverse feed control period ends when the welding current stops flowing (when the arc disappears).

  FIG. 4 is a block diagram of a welding power source for carrying out the arc welding control method according to the third embodiment. This figure corresponds to FIG. 1 described above, and the same reference numerals are given to the same blocks, and description thereof will not be repeated. In FIG. 1, a current detection circuit ID and a current conduction determination circuit CD are added to FIG. 1, and the reverse control period determination circuit STK in FIG. 1 is replaced with a second reverse control period determination circuit STK2. The voltage output period discrimination circuit STB is replaced with a second anti-stick voltage output period discrimination circuit STB2. Hereinafter, these blocks will be described with reference to FIG.

  The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id.

  The current energization determination circuit CD receives the current detection signal Id as described above, and determines that the welding current Iw is energized when this value is equal to or greater than a threshold value (about 10 A), and the current energization determination becomes a high level. The signal Cd is output.

  The second reverse feed control period determination circuit STK2 receives the welding start signal St, the short circuit determination signal Sd, and the current energization determination signal Cd, and receives the welding start signal St from a high level to a low level (welding end command). ) Is changed to High level when the short circuit determination signal Sd changes from High level to Low level (arc), and then Low when the current energization determination signal Cd changes to Low level (non-energization). A reverse control period signal Stk that is reset to the level is output.

  The second anti-stick voltage output period discriminating circuit STB2 receives the reverse control period signal Stk and is set to the High level when the reverse control period signal Stk changes to the High level, and the reverse control period signal Stk. The anti-stick voltage output period signal Stb that is reset to the low level is output when the signal changes to the low level or when it is delayed from that time.

  Since the timing chart of each signal at the end of welding in the welding power source of FIG. 4 showing the arc welding control method according to the third embodiment of the present invention is the same as FIG. 2 described above, description thereof will not be repeated. However, the following points are different. In FIG. 2, the arc length is gradually increased by the reverse control from time t14, and the arc cannot be maintained at time t15, and the arc disappears. When the arc disappears, the welding current Iw shown in FIG. In response to this, the reverse feed control period signal Stk shown in FIG. 5F changes to the Low level, so that the feed speed Fw shown in FIG. Similarly, when the welding current Iw is not energized at time t15, the anti-stick voltage output period signal Stb shown in FIG. 5G also changes to the low level, so the welding voltage Vw shown in FIG. Output stops.

  The third embodiment is based on the first embodiment, but the same applies to the case based on the second embodiment.

  According to the third embodiment described above, the feed is stopped and the reverse feed control is terminated when the welding current is not energized during the reverse feed control. Thereby, in addition to the effect of Embodiment 1 and 2, in Embodiment 3, there exist the following effects. In the first and second embodiments, the reverse feed control period has to be set in advance by experiments so as to be an appropriate value for each welding condition. On the other hand, in the third embodiment, since the reverse feed control period automatically ends when the arc disappears and the welding current is not energized, it is not necessary to set, and the work efficiency is improved.

[Embodiment 4]
In the invention of the fourth embodiment, the feed speed is set to be gradually decelerated during the reverse feed control. In the inventions of Embodiments 1 to 3, the feed speed is set to a constant speed during the reverse feed control.

  FIG. 5 is a block diagram of a welding power source for carrying out the arc welding control method according to the fourth embodiment. This figure corresponds to FIG. 1 described above, and the same reference numerals are given to the same blocks, and description thereof will not be repeated. In the figure, the reverse feed speed setting circuit FKR in FIG. 1 is replaced with a second reverse feed speed setting circuit FKR2. Hereinafter, this block will be described with reference to FIG.

  The second reverse feed speed setting circuit FKR2 receives the reverse feed control period signal Stk as an input, and reaches a predetermined initial value when the reverse feed control period signal Stk changes to a high level (reverse feed control period). A reverse feed speed setting signal Fkr is output that has a slope and decelerates and then gradually decelerates with time. Since Fkr is a reverse feed, it is a negative value, and since it decelerates, its absolute value becomes a value that decreases with time.

  The timing chart of each signal at the end of welding in the welding power source of FIG. 5 showing the arc welding control method according to the fourth embodiment of the present invention is the same as FIG. However, the following points are different. In FIG. 2, during the reverse feed control period Tk from time t14 to t15, as shown in FIG. 2B, the feed speed Fw has a slope up to an initial value of a predetermined reverse feed speed Fk. And then gradually decelerate until the end of the reverse feed control period Tk as time elapses.

  The fourth embodiment is based on the first embodiment, but the same applies to the second and third embodiments.

  According to the fourth embodiment described above, the feed speed is set to be gradually decelerated during the reverse feed control. Thereby, in addition to the effect of Embodiments 1-3, Embodiment 4 has the following effect. In the fourth embodiment, the feeding speed is gradually decelerated during the reverse feed control period and approaches 0, so that the variation in droplet size after the end of welding is reduced. For this reason, the next arc start property becomes better.

  According to the present invention, it is possible to provide an arc welding control method capable of stabilizing a welding state during an anti-stick period in welding in which a forward feed period and a reverse feed period are alternately switched.

  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 January 19, 2015 (Japanese Patent Application No. 2015-007972), the contents of which are incorporated herein.

DESCRIPTION OF SYMBOLS 1 Welding wire 2 Base material 3 Arc 4 Welding torch 5 Feed roll CD Current energization discrimination circuit Cd Current energization discrimination signal DV Drive circuit Dv Drive signal DV2 2nd drive circuit E Output voltage Ea Error amplification signal EBR Anti-stick output voltage setting circuit Ebr Anti-stick output voltage setting signal ECR Steady output voltage setting circuit Ecr Steady output voltage setting signal ED Output voltage detection circuit Ed Output voltage detection signal EI Current error amplification circuit Ei Current error amplification signal ER Output voltage setting circuit Er Output voltage setting signal EV Voltage error amplification circuit Ev Voltage error amplification signal Fa Average feed speed FAR Average feed speed setting circuit Far Average feed speed setting signal FC Feed control circuit Fc Feed control signal FCR Steady welding period feed speed setting circuit Fcr Steady welding Period feed speed setting signal Fk Reverse feed speed FKR Reverse feed Degree setting circuit Fkr Reverse feed speed setting signal FKR2 Second reverse feed speed setting circuit FR Feed speed setting circuit Fr Feed speed setting signal Fw Feed speed IBR Antistick current setting circuit Ibr Antistick current setting signal ID Current detection circuit Id Current detection signal Iw Welding current PM Power supply main circuit SD Short circuit determination circuit Sd Short circuit determination signal ST Welding start circuit St Welding start signal STB Antistick voltage output period determination circuit Stb Antistick voltage output period signal STB2 Second antistick Voltage output period discriminating circuit STK Reverse feed control period discriminating circuit Stk Reverse feed control period signal STK2 Second reverse feed control period discriminating circuit SW Power supply characteristic switching circuit Tb Anti-stick voltage output period Tf Period TFR Period setting circuit Tfr Period setting signal Tk Inverse Transmission control period VD Voltage detection circuit d voltage detection signal Vw welding voltage Wf amplitude WFR amplitude setting circuit Wfr amplitude setting signal WL reactor WM feed motor

Claims (9)

In the arc welding control method of performing welding by generating a short circuit period and an arc period by performing forward / reverse feed control for alternately switching the feeding speed of the welding wire between the forward feed period and the reverse feed period,
When a welding end command is input, the feed speed is switched from the forward / reverse feed control to the reverse feed control to end welding,
An arc welding control method characterized by the above. Switching to the reverse feed control is performed after transition from the short-circuit period to the arc period after the welding end command is input.
The arc welding control method according to claim 1, wherein: When the reverse control is continued for a predetermined period, the supply is stopped and the reverse control is terminated.
The arc welding control method according to claim 1, wherein the method is an arc welding control method. When the welding current is not energized during the reverse control, the supply is stopped and the reverse control is terminated.
The arc welding control method according to claim 1, wherein the method is an arc welding control method. Independently setting the end point of the reverse feed control and the stop point of the welding voltage output;
The arc welding control method according to claim 1, wherein the method is an arc welding control method. Stopping the output of the welding voltage when the reverse feed control is completed,
The arc welding control method according to claim 1, wherein the method is an arc welding control method. After switching to the reverse feed control, constant current control of the welding power source,
The arc welding control method according to claim 1, wherein the method is an arc welding control method. The feed speed is set to a constant speed during the reverse feed control.
The arc welding control method according to claim 1, wherein the method is an arc welding control method. During the reverse feed control, the feed speed is set to gradually decelerate.
The arc welding control method according to claim 1, wherein the method is an arc welding control method.

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