JP2021070029A - Arc welding method - Google Patents

Abstract

To provide a consumable electrode arc welding method by which proper welding mode can be automatically selected according to an average weld current value under various welding conditions.SOLUTION: An arc welding method comprises a short circuit transfer arc welding mode, a short circuit transfer/pulse arc welding mode in which short circuit transfer arc welding and pulse arc welding are periodically changed to perform welding, and a pulse arc welding mode, and feeds and welds a welding wire 1. In this method, before welding, at least one welding mode of the short circuit transfer arc welding mode, the short circuit transfer/pulse arc welding mode, and the pulse arc welding mode is allocated in association with an average weld current set value Iavr, and is automatically changed to a welding mode Mr, which has been allocated according to the average weld current set value Iavr to perform welding.SELECTED DRAWING: Figure 1

Description

The present invention includes a short-circuit transition arc welding mode, a short-circuit transition / pulse arc welding mode in which short-circuit transition arc welding and pulse arc welding are periodically switched and welded, and a pulse arc welding mode, and a welding wire is fed. It relates to an arc welding method for welding.

Welding power supply for consumable electrode arc welding equipped with short-circuit transition arc welding mode, short-circuit transition / pulse arc welding mode that periodically switches between short-circuit transition arc welding and pulse arc welding, and pulse arc welding mode is on sale. (See, for example, Patent Document 1). The welding operator selects an appropriate welding mode according to the welding conditions and performs welding.

Japanese Unexamined Patent Publication No. 2005-313179

The welding operator adjusts the average welding current value according to the welding conditions such as the plate thickness of the base metal and the shape of the joint to perform welding. At this time, if an appropriate welding mode is selected according to the average welding current value, the welding quality can be further improved. The average welding current value can be set by a remote regulator placed near the welder. However, the welding mode is generally selected on the front panel of the welding power source away from the weld. For this reason, the welding operator often adjusts only the average welding current value to perform welding without switching the welding mode. As a result, there is a problem that the welding quality is not the highest.

Therefore, an object of the present invention is to provide an arc welding method capable of automatically selecting an appropriate welding mode according to an average welding current value under various welding conditions.

In order to solve the above-mentioned problems, the invention of claim 1 is
It has a short-circuit transition arc welding mode, a short-circuit transition / pulse arc welding mode in which short-circuit transition arc welding and pulse arc welding are periodically switched and welded, and a pulse arc welding mode. In the welding method
Prior to welding, at least one welding mode of the short-circuit transition arc welding mode, the short-circuit transition / pulse arc welding mode, and the pulse arc welding mode is assigned in correspondence with the average welding current set value.
When welding is performed, the mode is automatically switched to the assigned welding mode according to the average welding current set value.
This is an arc welding method characterized by this.

The invention of claim 2 is
When the average welding current set value is less than the first reference current value, it is assigned to the short-circuit transition arc welding mode.
When the average welding current set value is equal to or more than the first reference current value and less than the second reference current value, it is assigned to the short circuit transition / pulse arc welding mode.
When the average welding current set value is equal to or greater than the second reference current value, the pulse arc welding mode is assigned.
The arc welding method according to claim 1, wherein the arc welding method is characterized in that.

The invention of claim 3 is
During the short-circuit transition arc welding mode or the short-circuit transition / pulse arc welding mode, the welding wire is synchronized with whether the welding state is the short-circuit period or the arc period. Performs forward and reverse feeding control,
The arc welding method according to claim 1 or 2, wherein the method is characterized by the above.

According to the present invention, an appropriate welding mode can be automatically selected according to the average welding current value under various welding conditions.

It is a block diagram of the welding power source for carrying out the arc welding method which concerns on Embodiment 1 of this invention. Each time of switching from the pulse arc welding period Ta to the short circuit transition arc welding period Tc in the welding power supply of FIG. 1 showing the arc welding method according to the first embodiment of the present invention in the short circuit transition / pulse arc welding mode. It is a signal timing chart. Each time of switching from the short-circuit transition arc welding period Tc to the pulse arc welding period Ta in the welding power supply of FIG. 1, which shows the arc welding method according to the first embodiment of the present invention in the short-circuit transition / pulse arc welding mode. It is a signal timing chart.

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

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

The power supply main circuit PM receives a commercial power supply (not shown) such as three-phase 200V as an input, performs output control by inverter control or the like according to an error amplification signal Ea described later, and outputs an output voltage E. Although not shown, this power supply main circuit PM is driven by a primary rectifier that rectifies a commercial power supply, a smoothing capacitor that smoothes the rectified DC, and the above-mentioned error amplification signal Ea that converts the smoothed DC into high-frequency AC. It is equipped with an inverter circuit that is used, a high-frequency transformer that steps down high-frequency AC to a voltage value suitable for welding, and a secondary rectifier that rectifies the stepped-down high-frequency AC to DC.

The reactor WL smoothes the welding current Iw and maintains a stable arc 3.

The feed motor WM receives a feed control signal Fc, which will be described later, as an input, and feeds mainly forward during the pulse arc welding period, and feeds forward and reverse during the short-circuit transition arc welding period to feed the welding wire 1. It will be sent by Fw. A motor having a high transient response is used as the feed motor WM. The feed motor WM may be installed near the tip of the welding torch 4 in order to accelerate the rate of change of the feed rate Fw of the welding wire 1 and the reversal of the feed direction. In addition, two feed motors WM may be used to form a push-pull feed system.

The welding wire 1 is fed in 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 metal 2. A welding voltage Vw is applied between the feeding tip (not shown) in the welding torch 4 and the base metal 2, and the welding current Iw is energized. Shield gas (not shown) is ejected from the tip of the welding torch 4 to shield the arc 3 from the atmosphere. As the shield gas, a mixed gas of argon gas and carbon dioxide gas is used when the material of the welding wire 1 is steel, and argon gas is used when the material of the welding wire 1 is aluminum.

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 EV takes the above-mentioned output voltage setting signal Er and the above-mentioned output voltage detection signal Ed as inputs, and amplifies the error between the output voltage setting signal Er (+) and the output voltage detection signal Ed (-). , Outputs the voltage error amplification signal Ev.

The current detection circuit ID detects the welding current Iw and outputs the current detection signal Id. The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The short-circuit discrimination circuit SD takes the above voltage detection signal Vd as an input, and when this value is less than the predetermined short-circuit discrimination value (about 10V), it determines that it is in the short-circuit period and reaches the High level. A short-circuit determination signal Sd that determines that the circuit is in the arc period and reaches the Low level is output.

The average welding current setting circuit IAVR outputs a predetermined average welding current setting signal Iavr.

The forward feed acceleration period setting circuit TUR outputs a predetermined forward feed acceleration period setting signal Tsur.

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

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

The reverse feed / deceleration period setting circuit TRDR outputs a predetermined reverse feed / deceleration period setting signal Trdr.

The forward peak value setting circuit WSR receives the timer signal Tm described later, the above average welding current setting signal Iavr, and the above short circuit discrimination signal Sd as inputs, and the timer signal Tm changes to the Low level (short circuit transition arc welding period Tc). During the period from that time until the short-circuit discrimination signal Sd first changes to the High level (short-circuit period), the initial value becomes a predetermined value.
During the other period, the forward peak value setting signal Wsr, which is a steady value calculated based on a predetermined function with the average welding current setting signal Iavr as an input, is output.

The reverse feed peak value setting circuit WRR receives the above average welding current setting signal Iavr as an input, and outputs a reverse feed peak value setting signal Wrr calculated based on a predetermined function.

The short-circuit arc feed rate setting circuit FCR includes the above-mentioned forward feed acceleration period setting signal Tsur, the above-mentioned forward feed deceleration period setting signal Tsdr, the above-mentioned reverse feed acceleration period setting signal Trur, and the above-mentioned reverse feed deceleration period setting signal Trdr. Using the above-mentioned forward peak value setting signal Wsr, the above-mentioned reverse peak value setting signal Wrr, and the above-mentioned short-circuit discrimination signal Sd as inputs, the feed rate pattern generated by the following processing is used as the short-circuit arc feed rate setting signal Fcr. Output as. When the short-circuit arc feed rate setting signal Fcr has a positive value, it is a normal feed period, and when it is a negative value, it is a reverse feed period.
1) From 0 during the normal feed acceleration period Tsu, which is determined by the normal feed acceleration period setting signal Tsur (however, immediately after switching to the short-circuit transition arc welding period Tc, the pulse feed rate setting signal Far), the normal feed peak value setting signal Wsr A short-circuit arc feeding speed setting signal Fcr that accelerates linearly up to the positive peak value Wsp, which is a fixed positive value, is output.
2) Subsequently, during the normal feed peak period Tsp, the short-circuit arc feed rate setting signal Fcr that maintains the above normal feed peak value Wsp is output.
3) When the short-circuit discrimination signal Sd changes from the Low level (arc period) to the High level (short-circuit period), the process shifts to the forward deceleration period Tsd determined by the forward deceleration period setting signal Tsdr, and from the above normal forward peak value Wsp. A short-circuit arc feeding speed setting signal Fcr that decelerates linearly to 0 is output.
4) Subsequently, during the reverse feed acceleration period Tru determined by the reverse feed acceleration period setting signal Trur, a short-circuit arc feed that linearly accelerates from 0 to the negative value reverse feed peak value Wrp determined by the reverse feed peak value setting signal Wrr. The feed rate setting signal Fcr is output.
5) Subsequently, during the reverse feed peak period Trp, the short-circuit arc feed rate setting signal Fcr that maintains the above reverse feed peak value Wrp is output.
6) When the short-circuit discrimination signal Sd changes from the High level (short-circuit period) to the Low level (arc period), it shifts to the reverse-forward deceleration period Trd determined by the reverse-forward deceleration period setting signal Trdr, and from the above reverse-forward peak value Wrp. A short-circuit arc feeding speed setting signal Fcr that decelerates linearly to 0 is output.
7) By repeating the above 1) to 6), a short-circuit arc feeding speed setting signal Fcr of a feeding pattern that changes into a positive or negative trapezoidal wave shape is generated.

The current reduction resistor R is inserted between the reactor WL and the welding torch 4. The value of this current-reducing resistor R is set to a value (about 0.5 to 3 Ω) that is 50 times or more larger than the resistance value (about 0.01 to 0.03 Ω) of the current-carrying path of the welding current Iw during the short-circuit period. To. When the current-reducing resistor R is inserted into the current-carrying path of the welding current Iw, the energy stored in the reactor WL and the reactor of the welding cable is rapidly consumed.

The transistor TR is connected in parallel with the current-reducing resistor R described above, and is controlled to be turned on or off according to a drive signal Dr described later.

The constriction detection circuit ND receives the above-mentioned short-circuit discrimination signal Sd, the above-mentioned voltage detection signal Vd, and the above-mentioned current detection signal Id as inputs, and receives the above-mentioned short-circuit discrimination signal Sd as a high level (short-circuit period) of the voltage detection signal Vd. Constriction detection that determines that the constriction formation state has reached the reference state when the voltage rise value reaches the reference value and reaches the High level, and reaches the Low level when the short-circuit discrimination signal Sd changes to the Low level (arc period). The signal Nd is output. Further, the constriction detection signal Nd may be changed to the High level when the differential value of the voltage detection signal Vd during the short-circuit period reaches the corresponding reference value. Further, the value of the voltage detection signal Vd is divided by the value of the current detection signal Id to calculate the resistance value of the droplet, and when the differential value of this resistance value reaches the corresponding reference value, the constriction detection signal Nd is obtained. It may be changed to a high level.

The low level current setting circuit ILR outputs a predetermined low level current setting signal Ilr. The current comparison circuit CM takes the low level current setting signal Ilr and the above current detection signal Id as inputs, and sets the current comparison signal Cm to the High level when Id <Ilr and the Low level when Id ≥ Ilr. Output.

The drive circuit DR receives the above-mentioned current comparison signal Cm and the above-mentioned constriction detection signal Nd as inputs, and when the constriction detection signal Nd changes to the High level, it changes to the Low level, and then when the current comparison signal Cm changes to the High level. The drive signal Dr that changes to the High level is output to the base terminal of the above-mentioned transistor TR. Therefore, when the constriction is detected, the drive signal Dr goes to the Low level, the transistor TR is turned off, and the current-reducing resistor R is inserted into the current-carrying path, so that the welding current Iw drops sharply. Then, when the value of the suddenly reduced welding current Iw decreases to the value of the low level current setting signal Ilr, the drive signal Dr becomes the High level and the transistor TR is turned on, so that the current reduction resistor R is short-circuited and normally. Return to the state of.

The short-circuit arc current setting circuit ICR receives the above-mentioned short-circuit discrimination signal Sd, the above-mentioned low-level current setting signal Ilr, and the above-mentioned constriction detection signal Nd as inputs, performs the following processing, and outputs the short-circuit arc current setting signal Icr.
1) When the short-circuit discrimination signal Sd is at the Low level (arc period), the short-circuit arc current setting signal Icr, which is the low-level current setting signal Ilr, is output.
2) When the short-circuit discrimination signal Sd changes to the High level (short-circuit period), the initial current set value becomes a predetermined value during the predetermined initial period, and then the short-circuit peak set value predetermined with the predetermined short-circuit slope. Outputs a short-circuit arc current setting signal Icr that rises to and maintains that value.
3) After that, when the constriction detection signal Nd changes to the High level, the short-circuit arc current setting signal Icr, which is the value of the low level current setting signal Ilr, is output.

The current drop time setting circuit TDR outputs a predetermined current drop time setting signal Tdr.

The small current period circuit STD receives the above-mentioned short-circuit discrimination signal Sd and the above-mentioned current drop time setting signal Tdr as inputs, and is determined by the current drop time setting signal Tdr from the time when the short-circuit discrimination signal Sd changes to the Low level (arc period). When the time elapses, the high level is reached, and then when the short circuit determination signal Sd reaches the high level (short circuit period), the low level signal Std is output.

The peak period setting circuit TPR receives the final pulse period signal Stf, which will be described later, as an input, and has a predetermined steady peak period when the final pulse period signal Stf is at the Low level, and is predetermined when the final pulse period signal Stf is at the High level. The peak period setting signal Tpr, which is the final peak period, is output.

The peak rise period setting circuit TUR receives the final pulse period signal Stf, which will be described later, as an input, and when the final pulse period signal Stf is at the Low level, it has a predetermined steady peak rise period, and when the final pulse period signal Stf is at the High level, it has a predetermined steady peak rise period. The peak rise period setting signal Tur, which is the final peak rise period determined in advance, is output.

The peak fall period setting circuit TPDR receives the final pulse period signal Stf, which will be described later, as an input, and when the final pulse period signal Stf is at the Low level, it has a predetermined steady peak fall period, and the final pulse period signal Stf is at the High level. At this time, the peak fall period setting signal Tpdr, which is the final peak fall period set in advance, is output.

The base period setting circuit TBR outputs a predetermined base period setting signal Tbr.

The peak current setting circuit IPR receives the above voltage error amplification signal Ev as an input, performs modulation control, and outputs a peak current setting signal Ipr. Modulation control is performed by integrating the voltage error amplification signal Ev such as Ipr = Ip0−∫Kp ・ Ev ・ dt. Ip0 is the initial value of the peak current value, and Kp is a constant for adjusting the gain of the peak current modulation control to an appropriate value.

The base current setting circuit IBR receives the above voltage error amplification signal Ev as an input, performs modulation control, and outputs a base current setting signal Ibr. Modulation control is performed by integrating the voltage error amplification signal Ev such as Ibr = Ib0−∫Kb ・ Ev ・ dt. Ib0 is the initial value of the base current value, and Kb is a constant for adjusting the gain of the base current modulation control to an appropriate value.

The pulse initial reverse feed period setting circuit TARR outputs a predetermined pulse initial reverse feed period setting signal Tarr.

The pulse initial current period setting circuit TASR outputs a predetermined pulse initial current period setting signal Tasr. The pulse initial current setting circuit IASR outputs a predetermined pulse initial current setting signal Iasr.

The pulse current setting circuit IAR includes a timer signal Tm described later, a peak period setting signal Tpr, a peak rising period setting signal Tur, a peak falling period setting signal Tpdr, a base period setting signal Tbr, and the above. Using the peak current setting signal Ipr, the base current setting signal Ibr, the pulse initial current period setting signal Tasr, and the pulse initial current setting signal Iasr as inputs, the following processing is performed to output the pulse current setting signal Iar. ..
1) When the timer signal Tm is at the Low level (short-circuit transition arc welding period), the value of the pulse initial current setting signal Iasr is output as the pulse current setting signal Iar.
2) From the time when the timer signal Tm changes from the Low level to the High level (pulse arc welding period), the value of the pulse initial current setting signal Isr is set to the pulse current during the pulse initial current period Tas determined by the pulse initial current period setting signal Tasr. Output as setting signal Iar.
3) Subsequently, during the peak rise period Tu determined by the peak rise period setting signal Tur, the value of the pulse initial current setting signal Isr (base current setting signal Ibr from the second pulse cycle) is used to obtain the peak current setting signal Ipr. The pulse current setting signal Iar that rises to the value is output.
4) Subsequently, during the peak period Tp determined by the peak period setting signal Tpr, the pulse current setting signal Iar that maintains the value of the peak current setting signal Ipr is output.
5) Subsequently, during the peak fall period Tpd determined by the peak fall period setting signal Tpdr, the pulse current setting signal Iar that drops from the value of the peak current setting signal Ipr to the value of the base current setting signal Ibr is output.
6) Subsequently, during the base period Tb determined by the base period setting signal Tbr, the pulse current setting signal Iar that maintains the value of the base current setting signal Ibr is output.
7) With the above 3) to 6) as one pulse period, the timer signal Tm is repeated until it changes to the Low level.

The pulse arc welding period setting circuit TAR outputs a predetermined pulse arc welding period setting signal Tar. The short-circuit transition arc welding period setting circuit TCR outputs a predetermined short-circuit transition arc welding period setting signal Tcr.

The welding mode setting circuit MR receives the above average welding current setting signal Iavr as an input.
At least one welding mode of short-circuit transition arc welding mode, short-circuit transition / pulse arc welding mode, and pulse arc welding mode is pre-allocated according to the average welding current value.
The welding mode setting signal Mr corresponding to the value of the average welding current setting signal Iavr is output.
For example, the welding mode setting signal Mr has a value of 1 when the short-circuit transition arc welding mode is selected, and has a value of 2 when the short-circuit transition / pulse arc welding mode is selected, and the pulse arc welding mode is set. When selected, the value is 3. The allocation method is illustrated below. Before welding, the welding operator or the welding manager performs the allocation so that the welding quality is good according to the welding conditions such as the plate thickness of the base metal, the shape of the joint, and the material.
(Assignment method 1)
When Iavr <150A, Mr = 1 (short-circuit transition arc welding mode)
When 150A ≤ Iavr <250A, Mr = 2 (short circuit transition / pulse arc welding mode)
When Iavr ≥ 250A, Mr = 3 (pulse arc welding mode)
(Assignment method 2)
When Iavr <200A, Mr = 1 (short-circuit transition arc welding mode)
When Iavr ≥ 200A, Mr = 3 (pulse arc welding mode)
(Assignment method 3)
Mr = 3 (pulse arc welding mode) regardless of the value of Iavr

The timer circuit TM includes the welding mode setting signal Mr, the pulse arc welding period setting signal Tar, the short-circuit transition arc welding period setting signal Tcr, the short-circuit discrimination signal Sd, the pulse current setting signal Iar, and the above. The base current setting signal Ibr of the above is input, the following processing is performed, and the timer signal Tm and the final pulse period signal Stf are output.
1) When the welding mode setting signal Mr = 1 (short-circuit transition arc welding mode), a timer signal Tm that continues the Low level is output. It also outputs the final pulse period signal Stf, which is at the Low level.
2) When the welding mode setting signal Mr = 3 (pulse arc welding mode), a timer signal Tm that continues the high level is output. It also outputs the final pulse period signal Stf, which is at the Low level.
3) When the welding mode setting signal Mr = 2 (short-circuit transition / pulse arc welding mode), the short-circuit transition arc welding period setting signal Tcr is used from the time when the timer signal Tm changes to the Low level (short-circuit transition arc welding period Tc). After the fixed period has elapsed, the timer signal Tm changes to the High level when the short-circuit discrimination signal Sd first changes to the Low level (arc period).
When a new pulse cycle is started after a period determined by the pulse arc welding period setting signal Tar has elapsed from the time when the timer signal Tm changes to the High level (pulse arc welding period Ta), the final pulse period Tsf is entered and the final pulse is entered. When the pulse current setting signal Iar becomes equal to the value of the base current setting signal Ibr during the cycle Tsf, the final pulse cycle Tsf is terminated and the timer signal Tm changes to the Low level.
The final pulse period signal Stf, which has a high level only during the final pulse period Tsf, is output.
Therefore, the pulse arc welding period Ta is the period of the pulse arc welding period setting signal Tar + the period until the final pulse period Tsf starts + the period of the final pulse period Tsf. The short-circuit transition arc welding period Tc is the period of the short-circuit transition arc welding period setting signal Tcr + the period until the end of the first short-circuit period thereafter.

The pulse initial reverse feed rate setting signal FAR outputs a negative value of a predetermined pulse initial reverse feed rate setting signal Farr.

The pulse positive feed rate setting circuit FASR receives the above-mentioned average welding current setting signal Iavr as an input, and outputs a positive value pulse positive feed rate setting signal Fasr calculated based on a predetermined function. Since the average welding current value is determined by the average feed rate, the average welding current value at the time of pulse arc welding is determined by this pulse positive feed setting signal Fasr.

The pulse feeding speed setting circuit FAR uses the above timer signal Tm, the above pulse initial reverse feeding period setting signal Tarr, the above pulse initial reverse feeding speed setting signal Farr, and the above pulse forward feeding speed setting signal Fasr. As an input, the following processing is performed, and the pulse feeding speed setting signal Far is output.
1) When the timer signal Tm is at the Low level (short-circuit transition arc welding period), the value of the pulse initial reverse feed rate setting signal Farr is output as the pulse feed rate setting signal Far.
2) Pulse initial reverse feed period setting from the time when the timer signal Tm changes from Low level to High level (pulse arc welding period) Pulse initial reverse feed period set by the signal Tarr During the pulse initial reverse feed speed setting. The value of the signal Farr is output as the pulse feeding speed setting signal Far.
3) Subsequently, during the period until the timer signal Tm changes to the Low level, the value of the pulse normal feed rate setting signal Fasr is output as the pulse feed rate setting signal Far.

In the feed rate setting circuit FR, the timer signal Tm, the short-circuit arc feed rate setting signal Fcr, and the pulse feed rate setting signal Far are input, and the timer signal Tm is set to a high level (pulse arc welding period Ta). ), The pulse feed rate setting signal Far is output as the feed rate setting signal Fr, and when the low level (short-circuit transition arc welding period Tc), the short-circuit arc feed rate setting signal Fcr is output as the feed rate setting signal Fr. Output as.

The feed control circuit FC receives the above feed speed setting signal Fr as an input, and feeds a feed control signal Fc for feeding the welding wire 1 at a feed rate Fw corresponding to the value of the feed rate setting signal Fr. Output to the above feed motor WM.

The current setting circuit IR receives the above timer signal Tm, the above short-circuit arc current setting signal Icr, and the above pulse current setting signal Iar as inputs, and when the timer signal Tm is at the High level (pulse arc welding period Ta), the pulse current. The setting signal Iar is output as the current setting signal Ir, and when the low level (short-circuit transition arc welding period Tc) is reached, the short-circuit arc current setting signal Icr is output as the current setting signal Ir.

The current error amplification circuit EI uses the above-mentioned current setting signal Ir and the above-mentioned current detection signal Id as inputs, amplifies the error between the current setting signal Ir (+) and the current detection signal Id (-), and amplifies the current error. Output the signal Ei.

The power supply characteristic switching circuit SW receives the above timer signal Tm, the above current error amplification signal Ei, the above voltage error amplification signal Ev, the above short circuit discrimination signal Sd, and the above small current period signal Std as inputs, and performs the following processing. Is performed, and the error amplification signal Ea is output.
1) From the time when the timer signal Tm is at the Low level and the short-circuit discrimination signal Sd changes to the High level (short-circuit period), the short-circuit discrimination signal Sd changes to the Low level (arc period) and the above delay period changes. During the period up to the elapsed time, the current error amplification signal Ei is output as the error amplification signal Ea.
2) During the subsequent large current arc period, the voltage error amplification signal Ev is output as the error amplification signal Ea.
3) During the small current arc period in which the small current period signal Std becomes the High level during the subsequent arc period, the current error amplification signal Ei is output as the error amplification signal Ea.
4) The period from the time when the timer signal Tm changes to the Low level until the short-circuit discrimination signal Sd first reaches the High level, and when the timer signal Tm is the High level, the current error amplification signal Ei is output as the error amplification signal Ea. To do.
By this circuit, the characteristics of the welding power supply during the short-circuit transition arc welding period Tc are the period from the start of the short-circuit transition arc welding period Tc to the first short circuit, the short-circuit period, the delay period and the small current arc period. Has a constant current characteristic, and is a small current period signal from the time when the above delay time elapses after the short circuit discrimination signal Sd changes from High to Low in the other large current arc period (when the timer signal Tm is Low). During the period from the time when Std changes from Low to High), the constant voltage characteristic is obtained. Further, the characteristics of the welding power source during the pulse arc welding period Ta are constant current characteristics.

2 and 3 are timing charts of each signal in the welding power supply of FIG. 1 when the welding mode setting signal Mr = 2 (short circuit transition / pulse arc welding mode). In the short-circuit transition / pulse arc welding mode, welding is performed by periodically switching between the short-circuit transition arc welding period and the pulse arc welding period.

FIG. 2 is a timing chart of each signal at the time of switching from the pulsed arc welding period Ta to the short-circuit transition arc welding period Tc in the welding power source of FIG. 1 showing the arc welding method according to the first embodiment of the present invention. The figure shows the case where the welding mode setting signal Mr = 2 (short circuit transition / pulse arc welding mode). FIG. (A) shows the time change of the feeding speed Fw, FIG. (B) shows the time change of the welding current Iw, and FIG. 3C shows the time change of the welding voltage Vw. ) Indicates the time change of the short-circuit discrimination signal Sd, FIG. (E) shows the time change of the small current period signal Std, FIG. (F) shows the time change of the timer signal Tm, and FIG. The time change of the final pulse period signal Stf is shown. Hereinafter, the operation of each signal will be described with reference to the figure.

The time t0 is a period determined by the pulse arc welding period setting signal Tar in FIG. 1 for the elapsed time from the time when the timer signal Tm shown in FIG. After reaching this time, it is time to start a new pulse cycle. At time t0, as shown in FIG. 6 (G), the final pulse period signal Stf changes to the High level and enters the final pulse period Tsf. As shown in FIG. 3B during the final pulse period Tsf at times t0 to t1, the peak current value Ip rises to the peak current value Ip determined by the peak current setting signal Ipr in FIG. 1 during the predetermined final peak rise period Tu. The transition current is energized. During the subsequent final peak period Tp, the above-mentioned peak current value Ip is energized. During the subsequent final peak fall fall period Tpd, a transition current that drops from the peak current value Ip to the base current value Ib determined by the base current setting signal Ib of FIG. 1 is energized. At time t1, when the final peak falling period Tpd ends and the welding current Iw becomes the above-mentioned base current Ib, the final pulse period signal Stf returns to the Low level and the final pulse, as shown in FIG. The cycle Tsf ends. The values of the final peak rising period Tu, the final peak period Tp, and the final peak falling period Tpd during the final pulse period Tsf are set to values at which the droplets formed during the final pulse period Tsf do not migrate.

The time t1 is a new pulse after a period determined by the pulse arc welding period setting signal Tar in FIG. 1 elapses from the time when the timer signal Tm shown in FIG. It becomes a cycle and enters the final pulse cycle Tsf, and during the final pulse cycle Tsf, the pulse current setting signal Iar of FIG. 1 becomes equal to the value of the base current setting signal Ibr of FIG. Then, at time t1, as shown in FIG. (F), the timer signal Tm changes from the High level to the Low level. Therefore, at time t1, the pulse arc welding period Ta is switched to the short-circuit transition arc welding period Tc. In the figure, during the period before the time t1, as shown in FIG. 3A, the feed rate Fw is normally fed at a constant speed determined by the pulse normal feed rate setting signal Fasr in FIG. .. As shown in FIG. 6C, the welding voltage Vw has a waveform similar to the welding current Iw. As shown in FIG. 3D, the short-circuit determination signal Sd remains at the Low level because the arc period continues. As shown in FIG. (E), the small current period signal Std remains at the Low level.

At time t1, as shown in FIG. (F), the timer signal Tm changes to the Low level and enters the short-circuit transition arc welding period Tc. In response to this, as shown in FIG. 1A, the feed rate Fw is accelerated to the normal feed peak value Wsp determined by the normal feed peak value setting signal Wsr in FIG. 1, and a short circuit occurs at time t3. Keep that value until you do. The positive peak value Wsp during this period is the period from when the timer signal Tm changes to the Low level until when the short-circuit discrimination signal Sd first changes to the High level (short-circuit period). It becomes a value. Subsequent forward peak values Wsp will be predetermined steady-state values. The initial value is set independently of the steady value so that the welded state becomes stable during this period. Initial value = steady value may be used.

During the period from the start of the short-circuit transition arc welding period Tc at time t1 to the occurrence of the first short-circuit at time t3, as shown in FIG. Therefore, the low level current value determined by the low level current setting signal Ilr in FIG. 1 is obtained.

The feed rate Fw shown in FIG. 1A is controlled by the value of the short-circuit arc feed rate setting signal Fcr output from the short-circuit arc feed rate setting circuit FCR of FIG. The feed rate Fw is determined by the normal feed acceleration period setting signal Tsur in FIG. 1, the normal feed peak period Tsp that continues until a short circuit occurs, and the positive feed deceleration period setting signal Tsdr in FIG. Forward / deceleration period Tsd, reverse feed acceleration period Tru determined by the reverse feed acceleration period setting signal Trur in FIG. 1, reverse feed peak period Trp that continues until an arc is generated, and reverse feed determined by the reverse feed deceleration period setting signal Trdr in FIG. It is formed from the deceleration period Trd. Further, the forward peak value Wsp is determined by the forward peak value setting signal Wsr in FIG. 1, and the reverse peak value Wrp is determined by the reverse peak value setting signal Wrr in FIG. As a result, the short-circuit arc feeding speed setting signal Fcr becomes a feeding pattern that changes in a substantially trapezoidal wave shape of positive and negative.

[Operation during short-circuit period from time t3 to t6]
When a short circuit occurs at time t3 during the normal feed peak period Tsp, the welding voltage Vw drops sharply to a short circuit voltage value of several V as shown in FIG. The short-circuit discrimination signal Sd changes to the High level (short-circuit period). In response to this, the process shifts to the predetermined normal feed deceleration period Tsd at times t3 to t4, and as shown in FIG. .. For example, the forward deceleration period Tsd = 1 ms is set.

As shown in FIG. 3A, the feed rate Fw enters the predetermined reverse feed acceleration period Tru at times t4 to t5, and accelerates from 0 to the above-mentioned reverse feed peak value Wrp. The short-circuit period continues during this period. For example, the reverse feed acceleration period Tru = 1 ms is set.

When the reverse feed acceleration period Tru ends at time t5, the feed rate Fw enters the reverse feed peak period Trp and becomes the above reverse feed peak value Wrp, as shown in FIG. The reverse peak period Trp continues until an arc is generated at time t6. Therefore, the period from time t3 to t6 is the short-circuit period. The reverse peak period Trp is not a predetermined value, but it is about 4 ms. For example, the reverse peak value Wrp = -60 m / min is set.

As shown in FIG. 3B, the welding current Iw during the short-circuit period from time t3 to t6 becomes a predetermined initial current value during the predetermined initial period. After that, the welding current Iw rises at a predetermined short-circuit inclination, and maintains that value when the predetermined short-circuit peak value is reached.

As shown in FIG. 6C, the welding voltage Vw rises from the point where the welding current Iw reaches the peak value at the time of short circuit. This is because the back feed of the welding wire 1 and the action of the pinch force due to the welding current Iw gradually form a constriction in the droplets at the tip of the welding wire 1.

After that, when the voltage rise value of the welding voltage Vw reaches the reference value, it is determined that the constriction formation state has reached the reference state, and the constriction detection signal Nd in FIG. 1 changes to the High level.

In response to the constriction detection signal Nd reaching the High level, the drive signal Dr in FIG. 1 becomes the Low level, so that the transistor TR in FIG. Will be inserted. At the same time, the short-circuit arc current setting signal Icr of FIG. 1 becomes smaller than the value of the low-level current setting signal Ilr. Therefore, as shown in FIG. 6B, the welding current Iw sharply decreases from the peak value at the time of short circuit to the low level current value. Then, when the welding current Iw decreases to a low level current value, the drive signal Dr returns to the high level, so that the transistor TR is turned on and the current reducing resistor R is short-circuited. As shown in FIG. 3B, the welding current Iw has a low level until the predetermined delay period elapses from the recurrence of the arc because the short-circuit arc current setting signal Icr remains the low level current setting signal Ilr. Maintain the current value. Therefore, the transistor TR is turned off only during the period from the time when the constriction detection signal Nd changes to the High level until the welding current Iw decreases to the low level current value. As shown in FIG. 3C, the welding voltage Vw decreases once and then rises sharply because the welding current Iw becomes small. Each of the above-mentioned parameters is set to the following values, for example. Initial current = 40A, initial period = 0.5ms, short-circuit slope = 180A / ms, short-circuit peak value = 400A, low-level current value = 50A, delay period = 0.5ms.

[Operation during arc period from time t6 to t9]
At time t6, when the constriction progresses due to the pinch force due to the reverse feed of the welding wire and the energization of the welding current Iw and an arc is generated, the welding voltage Vw is an arc voltage value of several tens of V as shown in FIG. As shown in FIG. 3D, the short-circuit discrimination signal Sd changes to the Low level (arc period). In response to this, the process shifts to the predetermined reverse feed deceleration period Trd at times t6 to t7, and as shown in FIG. (A), the feed rate Fw decelerates from the above reverse feed peak value Wrp to 0. ..

When the reverse feed deceleration period Trd ends at time t7, the process shifts to the predetermined forward feed acceleration period Tsu at times t7 to t8. During this normal feed acceleration period Tsu, as shown in FIG. 6A, the feed rate Fw accelerates from 0 to the above normal feed peak value Wsp. The arc period continues during this period. For example, the forward acceleration period Tsu = 1 ms is set.

When the normal feed acceleration period Tsu ends at time t8, the feed rate Fw enters the normal feed peak period Tsp and reaches the above normal feed peak value Wsp, as shown in FIG. The arc period continues during this period. The forward peak period Tsp continues until a short circuit occurs at time t9. Therefore, the period from time t6 to t9 is the arc period. Then, when a short circuit occurs, the operation returns to the operation at time t3. The forward peak period Tsp is not a predetermined value, but it is about 4 ms. For example, the forward peak value Wsp = 70 m / min is set.

When an arc is generated at time t6, as shown in FIG. 6C, the welding voltage Vw rapidly increases to an arc voltage value of several tens of V. On the other hand, as shown in FIG. 6B, the welding current Iw continues to have a low level current value during the delay period from time t6 to t61. After that, from time t61, the welding current Iw rapidly increases to a peak value, and then gradually decreases to a large current value. During the large current arc period from time t61 to t81, the feedback control of the welding power source is performed by the voltage error amplification signal Ev of FIG. 1, so that the constant voltage characteristic is obtained. Therefore, the value of the welding current Iw during the high current arc period changes depending on the arc load.

At time t81, when the current drop time determined by the current drop time setting signal Tdr in FIG. 1 elapses after the arc is generated at time t6, the small current period signal Std changes to the High level as shown in FIG. To do. In response to this, the welding power supply is switched from the constant voltage characteristic to the constant current characteristic. Therefore, as shown in FIG. 6B, the welding current Iw drops to a low level current value and maintains that value until the time t9 when the short circuit occurs. Similarly, as shown in FIG. 6C, the welding voltage Vw also decreases. The small current period signal Std returns to the Low level when a short circuit occurs at time t9. During the short-circuit transition arc welding period Tc thereafter, the operations at times t3 to t9 are repeated.

The short-circuit transition arc welding period Tc includes a plurality of cycles of repeating the short-circuit period and the arc period. One short-circuit / arc cycle is, for example, about 10 ms. The short-circuit transition arc welding period Tc is, for example, about 50 to 500 ms. In FIG. 2, it is a case where the short-circuit transition arc welding period Tc is switched to at the start of the base period in which the droplets do not migrate. In addition to this, it may be switched in the middle of the base period Tb.

FIG. 3 is a timing chart of each signal at the time of switching from the short-circuit transition arc welding period Tc to the pulse arc welding period Ta in the welding power supply of FIG. 1 showing the arc welding method according to the first embodiment of the present invention. The figure shows the case where the welding mode setting signal Mr = 2 (short circuit transition / pulse arc welding mode). FIG. (A) shows the time change of the feed rate Fw, FIG. (B) shows the time change of the welding current Iw, and FIG. 3C shows the time change of the welding voltage Vw. ) Indicates the time change of the short-circuit discrimination signal Sd, FIG. 3E shows the time change of the small current period signal Std, and FIG. FF shows the time change of the timer signal Tm. Hereinafter, the operation of each signal will be described with reference to the figure.

At time t1, as shown in FIG. 3B, the welding current Iw has a low level current value because it is the time when the short circuit is released and the arc is regenerated. Then, at time t1, after the period determined by the short-circuit transition arc welding period setting signal Tcr of FIG. 1 elapses from the time when the timer signal Tm shown in FIG. Since the short-circuit discrimination signal Sd first changes to the Low level (arc period), the timer signal Tm changes from the Low level to the High level as shown in FIG. Therefore, at time t1, the short-circuit transition arc welding period Tc is switched to the pulse arc welding period Ta. In the figure, during the period before the time t1, as shown in the figure (A), the feed rate Fw is in the state of the reverse feed peak value Wrp. As shown in FIG. 6C, the welding voltage Vw is a short-circuit voltage value. As shown in FIG. 3D, the short-circuit discrimination signal Sd changes from the high level (short-circuit period) to the low level (arc period) at time t1. As shown in FIG. (E), the small current period signal Std remains at the Low level.

At time t1, as shown in FIG. (F), the timer signal Tm changes to the High level and enters the pulse arc welding period Ta. In response to this, as shown in FIG. 1A, the feed rate Fw enters the pulse initial reverse feed period Tair determined by the pulse initial reverse feed period setting signal Tarr in FIG. The feed rate Fw during the pulse initial reverse feed period Tair at times t1 to t2 is the pulse initial reverse feed rate Fa determined by the pulse initial reverse feed rate setting signal Farr in FIG. When the pulse initial reverse feeding period Tair ends at time t2, as shown in FIG. 3A, the feeding speed Fw is the pulse normal feeding speed Fas determined by the pulse normal feeding speed setting signal Fasr in FIG. It becomes, and it is delivered normally at a constant feeding speed.

At the same time, when the pulse arc welding period Ta is entered at time t1, the welding current Iw enters the pulse initial current period Tas determined by the pulse initial current period setting signal Tasr of FIG. 1, as shown in FIG. The welding current Iw during the pulse initial current period Tas at times t1 to t3 is the pulse initial current Ias determined by the pulse initial current setting signal Isr of FIG.

After time t3, it becomes a steady period. As shown in FIG. 3B, during the predetermined steady-state peak rise period Tu at times t3 to t4, a transition current that rises to the peak current value Ip determined by the peak current setting signal Ipr in FIG. 1 is energized. During the predetermined steady peak period Tp at times t4 to t5, the above-mentioned peak current value Ip is energized. During the predetermined steady-state peak fall period Tpd at times t5 to t6, a transition current that drops from the above-mentioned peak current value Ip to the base current value Ib determined by the base current setting signal Ibr of FIG. 1 is energized. During the predetermined base period Tb at times t6 to t7, the above-mentioned base current value Ib is energized. During the pulse arc welding period Ta, the welding power source has a constant current characteristic. For this purpose, the welding current Iw is set by the pulse current setting signal Iar of FIG. As shown in FIG. 6C, the welding voltage Vw has a waveform similar to the current waveform. The period from time t3 to t7 is one pulse period Tf. In order to maintain the arc length at an appropriate value, the peak current Ip and the base current Ib are modulated and controlled so that the average value of the welding voltage Vw becomes equal to the target value (current modulation control). Other modulation control methods include frequency modulation control that modulates the pulse period Tf, peak period modulation control that modulates the peak period Tp, and the like. In any modulation control, the welding state can be improved by setting the so-called 1-pulse period 1-droplet transition state in which one droplet is transferred during the 1-pulse period Tf. Numerical examples of each parameter are Tu = 1.5ns, Tp = 0.2ms, Tpd = 1.5ms, Tb = 7ms, Ip = 350 to 450A and Ib = 30 to 80A.

The pulse arc welding period Ta includes a plurality of pulse periods Tf. The pulse period Tf is, for example, about 10 ms. The pulse arc welding period Ta is, for example, about 50 to 500 ms.

At time t1, when the pulse arc welding period Ta is started, the arc length is in a very short state because it is immediately after the short circuit is released. The pulse initial reverse feed period Tair from time t1 is provided so that the arc length becomes longer to a desired value. By energizing the first peak current Ip from the time t3 after increasing the arc length to a desired value, the droplet formation state can be stabilized from the first cycle. This makes it possible to smoothly switch from the short-circuit transition arc welding period Tc to the pulse arc welding period Ta. .. Therefore, the pulse initial reverse feed period Tai and the pulse initial reverse feed rate Fa are set to values that increase the arc length to a desired value. For this purpose, the pulse initial reverse feed period Tair is set to at least a longer period than the reverse feed deceleration period Trd in FIG. Further, the pulse initial reverse feed rate Fa is a value smaller than the reverse feed peak value Wrp in FIG. For example, Tar = 3ms and Fa = -6m / min.

Further, the pulse initial reverse feed period Tair is set as a period during which the welding voltage Vw rises to the reference voltage value. The welding voltage Vw is proportional to the arc length. Therefore, by setting the reference voltage value to a value corresponding to the desired arc length, the pulse initial reverse feed period Tair can be automatically set, and the parameter setting work becomes easy.

Further, during the pulse initial reverse feed period Tair, the welding current Iw is maintained at the pulse initial current Ias, which is a value larger than the base current Ib and smaller than the peak current Ip. The pulse initial current Ias is energized during the predetermined pulse initial current period Tas. It is set so that Tar <Tas. By setting the pulse initial current Ias to a value larger than the base current Ib, it is possible to promote the melting of the welding wire and prevent the re-short circuit between the welding wire and the base metal in a short period of the arc length. Therefore, the sputtering at the time of switching to the pulse arc welding period Ta can be reduced, and the switching can be made smoother. By setting the pulse initial current Ias to a value smaller than the peak current Ip, it is possible to prevent the arc length from suddenly burning up and the arc length from becoming too long than the desired value. For example, Tas = 5ms and Ias = 100A.

Further, after the pulse initial reverse feed period Tair has elapsed, the first peak current Ip is energized. That is, it means that Tar <Tas is set. By starting the first pulse cycle after the end of the pulse initial reverse feed period Tair, the droplet transition state in the first pulse cycle can be reliably stabilized.

The timing chart of each signal in the welding power supply of FIG. 1 when the welding mode setting signal Mr = 1 (short-circuit transition arc welding mode) of FIG. 1 is the same as the time t3 to t9 of FIG. 2 described above will be described. Does not repeat. Further, the timing chart of each signal in the welding power supply of FIG. 1 when the welding mode setting signal Mr = 3 (pulse arc welding mode) of FIG. 1 is the same as the time t3 to t7 of FIG. 3 described above. The explanation is not repeated.

According to the first embodiment described above, at least one of the short-circuit transition arc welding mode, the short-circuit transition / pulse arc welding mode, and the pulse arc welding mode corresponds to the average welding current set value before welding. When the welding mode is assigned and welding is performed, the welding mode is automatically switched to the assigned welding mode according to the average welding current set value and welding is performed. Therefore, in the present embodiment, an appropriate welding mode can be automatically selected according to the average welding current value under various welding conditions. As a result, the welding operator can perform welding in the welding mode most suitable for the welding conditions only by adjusting the average welding current value, so that the best welding quality can be easily obtained.

Further, according to the present embodiment, when the average welding current set value is less than the first reference current value, it is assigned to the short-circuit transition arc welding mode, and the average welding current set value is equal to or more than the first reference current value and the second reference current value. If it is less than, it is assigned to the short-circuit transition / pulse arc welding mode, and if the average welding current set value is equal to or more than the second reference current value, it is assigned to the pulse arc welding mode. In this way, in the present embodiment, the amount of spatter generated can be reduced in each current region.

Further, according to the present embodiment, whether the welding state is the short-circuit period or the arc period during the short-circuit transition arc welding mode or the short-circuit transition / pulse arc welding mode. The forward and reverse feeding control of the welding wire is performed in synchronization with.
In this way, in the present embodiment, the amount of spatter generated during short-circuit transition arc welding can be further reduced.

1 Welding wire
2 Base material
3 arc
4 Welding torch
5 Feeding roll CM Current comparison circuit Cm Current comparison signal DR Drive circuit Dr Drive signal E Output voltage Ea Error amplification 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 Pulse initial reverse feed rate FAR Pulse feed rate setting circuit Far Pulse feed rate setting signal FAR Pulse initial reverse feed rate setting signal Farr Pulse initial reverse feed Feed rate setting signal FASR Pulse normal feed rate setting circuit Fasr Pulse normal feed rate setting signal FC Feed control circuit Fc Feed control signal FCR Short-circuit arc feed rate setting circuit Fcr Short-circuit arc feed rate setting signal FR Feed rate Setting circuit Fr Feeding speed setting signal Fw Feeding speed IAR Pulse current setting circuit Iar Pulse current setting signal Ias Pulse initial current IASR Pulse initial current setting circuit Iasr Pulse initial current setting signal IAVR Average welding current setting circuit Iavr Average welding current setting signal Ib base current IBR base current setting circuit Ibr base current setting signal ICR short-circuit arc current setting circuit Icr short-circuit arc current setting signal ID current detection circuit Id current detection signal ILR low level current setting circuit Ilr low level current setting signal Ip peak current IPR peak Current setting circuit Ipr Peak current setting signal IR Current setting circuit Ir Current setting signal Iw Welding current NR Welding mode setting circuit Mr Welding mode setting signal ND Constriction detection circuit Nd Constriction detection signal PM Power supply Main circuit R Low voltage resistor SD Short circuit discrimination circuit
Sd Short circuit discrimination signal STD Small current period circuit Std Small current period signal Stf Final pulse period signal SW Power supply characteristic switching circuit Ta Pulse arc welding period Tair Pulse initial reverse feed period TAR Pulse arc welding period setting circuit Tar Pulse arc welding period setting signal TARR pulse initial reverse feed period setting circuit Tarr pulse initial reverse feed period setting signal Tas pulse initial current period TASR pulse initial current period setting circuit Tasr pulse initial current period setting signal Tb base period TBR base period setting circuit Tbr base period setting signal Tc Short-circuit transition arc welding period TCR Short-circuit transition arc welding period setting circuit Tcr Short-circuit transition arc welding period setting signal TDR Current drop time setting circuit Tdr Current drop time setting signal Tf Pulse cycle TM Timer circuit Tm Timer signal Tp Peak period TPR Peak period setting Circuit Tpr Peak period setting signal Tpd Peak falling period TPDR Peak falling period setting circuit Tpdr Peak falling period setting signal TR Transistor Trd Reverse feed deceleration period TRDR Reverse feed deceleration period setting circuit Trdr Reverse feed deceleration period setting signal Trp Reverse feed peak Period Tru Reverse feed acceleration period TRUR Reverse feed acceleration period setting circuit Trur Reverse feed acceleration period setting signal Tsd Forward feed deceleration period TSDR Forward feed deceleration period setting circuit Tsdr Forward feed deceleration period setting signal Tsf Final pulse cycle Tsp Forward feed peak period Tsu positive Feed acceleration period TUR Forward acceleration period setting circuit Tsur Forward acceleration period setting signal Tu Peak rise period TUR Peak rise period setting circuit Tur Peak rise period setting signal VD Voltage detection circuit Vd Voltage detection signal Vw Welding voltage WL Reactor WM Feed motor Wrp Reverse feed peak value WRR Reverse feed peak value setting circuit Wrr Reverse feed peak value setting signal Wsp Forward feed peak value WSR Forward feed peak value setting circuit Wsr Forward feed peak value setting signal

Claims (3)

It has a short-circuit transition arc welding mode, a short-circuit transition / pulse arc welding mode that periodically switches between short-circuit transition arc welding and pulse arc welding, and a pulse arc welding mode, and is an arc that feeds and welds welding wires. In the welding method
Prior to welding, at least one welding mode of the short-circuit transition arc welding mode, the short-circuit transition / pulse arc welding mode, and the pulse arc welding mode is assigned in correspondence with the average welding current set value.
When welding is performed, the mode is automatically switched to the assigned welding mode according to the average welding current set value.
An arc welding method characterized by that. When the average welding current set value is less than the first reference current value, it is assigned to the short-circuit transition arc welding mode.
When the average welding current set value is equal to or more than the first reference current value and less than the second reference current value, it is assigned to the short circuit transition / pulse arc welding mode.
When the average welding current set value is equal to or greater than the second reference current value, the pulse arc welding mode is assigned.
The arc welding method according to claim 1. During the short-circuit transition arc welding mode or the short-circuit transition / pulse arc welding mode, the welding wire is synchronized with whether the welding state is the short-circuit period or the arc period. Performs forward and reverse feeding control,
The arc welding method according to claim 1 or 2.

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