JP2011088209A - Carbon dioxide pulsed arc welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high quality welding having reduced sputters by stabilizing the formation and withdrawal state of droplets in consumable electrode type carbon dioxide pulsed arc welding. <P>SOLUTION: There is provided a carbon dioxide pulsed arc welding method in which welding are repeated with a peak time Tp of energizing a peak current Ip and a base time Tb energizing a base current Ib at a one pulse period of Tpb. In the method, droplets with a desired size are formed at the tip of a welding wire by vibrating the peak current Ip at an amplitude Ws and a vibration period Ts during the peak time Tp, and the formed droplets are smoothly transferred to a molten pool by short circuiting transfer during the base time Tb. Thus, since the droplets formed during the peak time Tp is transferred by short circuiting transfer during the base time Tb, one pulse period one droplet transfer state can be achieved. In this way, welding having reduced sputters is made possible. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a carbon dioxide pulse arc welding method for performing stable droplet transfer in consumable electrode type pulse arc welding using a shield gas containing carbon dioxide as a main component.

  Consumable electrode type pulse arc welding using a shielding gas mainly composed of argon gas is widely used. As the shielding gas mainly composed of argon gas, when the base material is a steel material, 20% by volume carbon dioxide gas + 80% by volume argon gas is used (mag pulse welding), and when the base material is an aluminum material. 100 vol% argon gas is used (Migpulse welding). In the pulse arc welding using such a shielding gas mainly composed of argon gas, the droplet transfer becomes a fine particle as much as the diameter of the welding wire and becomes a spray transfer state that is periodically performed stably. Good welding with less spatter generation can be performed. Below, the pulse arc welding using the shielding gas which has argon gas as a main component is demonstrated.

  FIG. 5 is a general current / voltage waveform diagram of pulse arc welding using a shielding gas containing argon gas as a main component. FIG. 4A shows the change over time of the welding current Iw for energizing the arc, and FIG. 4B shows the change over time of the welding voltage Vw between the welding wire and the base material. Hereinafter, a description will be given with reference to FIG.

  During the peak period Tp from time t1 to t2, a peak current Ip greater than or equal to the critical current value is applied to form and transfer droplets at the tip of the welding wire as shown in FIG. ), A peak voltage Vp proportional to the arc length is applied between the welding wire and the base material.

  During the base period Tb from time t2 to t3, as shown in FIG. 5A, the base current Ib having a small current value is energized to prevent the formation of droplets, as shown in FIG. In addition, a base voltage Vb is applied. The welding is performed by repeating the period from time t1 to t3 as the pulse period Tpb.

  In order to perform good pulse arc welding, it is important to maintain the arc length at an appropriate value. In order to maintain the arc length at an appropriate value, the following output control (arc length control) is performed. The arc length is substantially proportional to the welding voltage average value Vav indicated by a broken line in FIG. For this purpose, the welding voltage average value Vav is detected, and the output for changing the welding current average value Iav indicated by the broken line in FIG. 5A so that the detected value becomes equal to the welding voltage set value corresponding to the appropriate arc length. Take control. When the welding voltage average value Vav is larger than the welding voltage set value, the arc length is longer than the appropriate value. Therefore, the welding current average value Iav is decreased to reduce the wire melting rate and shorten the arc length. To do. Conversely, when the welding voltage average value Vav is smaller than the welding voltage set value, the arc length is shorter than the appropriate value, so the welding current average value Iav is increased to increase the wire melting rate and the arc length is increased. To be. In general, a value obtained by smoothing the welding voltage Vw is often used as the welding voltage average value Vav.

  In the above description, frequency modulation control and pulse width modulation control are mainly used as the output control of the welding power source for changing the welding current average value Iav. In the frequency modulation control, the peak current Ip, the base current Ib, and the peak period Tp are fixed to predetermined values, and the length of the base period Tb is controlled so that the welding voltage average value Vav becomes equal to the welding voltage setting value. Since changing the base period Tb changes the pulse period Tpb, this method is called frequency modulation control. In the pulse width modulation control, the peak current Ip, the base current Ib, and the pulse period Tpb are fixed to predetermined values, and the length of the peak period Tp is controlled so that the welding voltage average value Vav becomes equal to the welding voltage setting value. The

  Next, droplet transfer will be described with reference to FIG. By applying the peak current Ip, the tip of the welding wire is melted to form a droplet. At this time, since the shielding gas containing argon gas as a main component is used, the anode points of the arc are widely distributed throughout the droplet without concentrating on the droplet. For this reason, no pushing force acts on the droplet. When the peak current Ip is applied to the formed droplet, an electromagnetic pinch force acts on the droplet to cause constriction. And before and after the end of the peak period Tp (immediately before the end, at the end or immediately after the end), the droplets are detached and move to the molten pool. The combination of the peak current Ip and the peak period Tp is called a unit pulse condition, and is set to a value at which droplets having the diameter of the welding wire are formed and detached. Therefore, the droplets are sprayed as a fine particle about the diameter of the welding wire every peak period Tp. This state is referred to as a 1 pulse 1 droplet transfer state. In this way, welding with very little spatter generation becomes possible.

    As described above, in the pulse arc welding using the shield gas containing argon gas as a main component, a stable spray transfer state in which one pulse per droplet transfer occurs. Here, since the cost of argon gas is higher than that of carbon dioxide, attempts have been made to reduce the cost of shielding gas by decreasing the proportion of argon gas and increasing the proportion of carbon dioxide. . However, in the mixed gas of carbon dioxide gas and argon gas, when the ratio of carbon dioxide gas exceeds 30% by volume, stable spray transfer becomes gradually difficult for the reason described below. In particular, when a shield gas containing carbon dioxide as a main component with a carbon dioxide ratio exceeding 50% by volume is used, a stable spray transfer state is not achieved, and large spatters are generated. In the following description, when it is described as a shield gas containing carbon dioxide as a main component, it means a mixed gas in which the ratio of carbon dioxide exceeds 50% by volume. When a shield gas containing carbon dioxide as a main component is used, the anode point of the arc is concentrated on the lowest part of the droplet when the peak current Ip is applied. This is because the potential gradient of carbon dioxide gas is larger than that of argon gas, so that the action of minimizing the arc length works. As a result, the temperature of the anode point becomes extremely high, the metal vapor is blown out, and acts on the droplet as a pushing force. That is, when the peak current Ip is energized, a droplet is formed and this pushing force acts, and the droplet is not easily detached. In this state, in order to forcibly detach the droplet, it is necessary to make the peak period Tp 3-5 times longer than the normal value, grow the droplet large, and detach by gravity. . However, if this is done, the droplets will be separated into large lumps about several times the diameter of the welding wire and large spatter will be generated. Furthermore, this large droplet will move randomly without synchronizing with the energization of the peak current Ip, the welding state becomes unstable, and the welding quality also deteriorates. In order to solve the above-described problems in pulse arc welding using a shielding gas containing carbon dioxide as a main component (hereinafter referred to as carbon dioxide pulse arc welding), the following conventional techniques have been proposed.

  In the invention of Patent Document 1, the first half period of the peak current Ip is set to a larger value than the second half period, and is stepped downward. By doing so, droplets are formed in the latter half period of the peak current Ip, the droplets are shaped in the subsequent base period Tb, and the droplets are transferred in the first half period of the subsequent peak current Ip. Further, in the inventions of Patent Documents 2 to 4, the peak current Ip is energized as a plurality of peak current groups to stabilize the formation of droplets and facilitate the transfer.

JP 60-56486 A JP-A 61-17369 JP-A-1-254385 JP 2007-237270 A

  As described above, various proposals as shown in Patent Documents 1 to 4 have been made in order to improve formation and separation of droplets in carbon dioxide pulse arc welding. However, even at the present time, it cannot be said that carbon dioxide pulse arc welding has been put into practical use, and a welding apparatus for carbon dioxide pulse arc welding has not been sold. This indicates that there is still a problem even if the improvements proposed in Patent Documents 1 to 4 are implemented.

  According to the invention of Patent Literature 1, although the droplet transfer probability is increased by the peak current in the first half period, the droplet transfer still frequently occurs randomly without being synchronized with the peak current. This increases the peak current value in the first half period to form a constriction at the top of the droplet to promote separation, but on the other hand, the push-up force also increases so that the droplet does not reliably separate. Because. Moreover, according to invention of patent documents 2-4, formation of a droplet can be made smooth by energizing a peak current as a plurality of peak current groups. This is because the pushing force acting on the droplets can be dispersed when the plurality of peak current groups are energized rather than when the continuous peak current is energized, so that the formation of the droplets becomes smooth. However, in order to release the formed droplet by the peak current, it is necessary to form a constriction on the upper portion of the droplet, and at this time, a pushing force acts simultaneously. As a result, it is difficult to reliably remove the droplets even by energization of a plurality of peak current groups. Therefore, in the inventions of Patent Documents 2 to 4, although the formation of droplets is improved, there remains a problem in reliable separation of the droplets.

  Here, considering direct current carbon dioxide arc welding of a steel material, in a current region where the average welding current value is less than about 200 A, the droplets are short-circuited. That is, the arc period and the short-circuit period are periodically repeated, and the droplet formed during the arc period shifts during the short-circuit period. By precisely controlling the welding current during this short-circuit period, the generation of spatter can be reduced. However, pulse arc welding (mag pulse welding or MIG pulse welding) using a shielding gas containing argon gas as a main component can further reduce the generation of spatter. However, in this current region, it can be said that the amount of spatter of carbon dioxide arc welding is at a level that does not cause a problem in practice. When the average welding current value is in a current range of about 200 A or more, when the arc length is long, globule transition occurs, and the droplets migrate by free fall without being short-circuited by gravity. For this reason, the occurrence of spatter is small. In order to perform high-speed welding with a welding speed of 80 cm / min or higher in this current region, it is necessary to perform welding with a short arc length in order to prevent welding defects such as undercut. When the arc length is shortened, the droplets are transferred with a short circuit. In addition, since the timing at which the short circuit occurs is random, the size of the droplets varies in size, and the irregular droplet transfer state occurs, resulting in the occurrence of many large spatters. Therefore, when high-speed welding is performed in a current region of 200 A or more, the occurrence of spatter can be reduced by performing pulse arc welding using a shield gas mainly composed of argon gas.

  From the above, welding is performed using a shielding gas containing carbon dioxide as a main component, and the welding conditions for which the generation of spatter is to be reduced is particularly when high-speed welding is performed in a current range of 200 A or more. . Accordingly, an object of the present invention is to reduce the amount of spatter generated compared with carbon dioxide arc welding by improving the droplet transfer state of carbon dioxide pulse arc welding in high-speed welding in a current region of 200 A or more. .

In order to solve the above-described problems, the invention of claim 1 uses a shield gas mainly composed of carbon dioxide gas, feeds a welding wire, and supplies a peak period and a base current for supplying a peak current. In the carbon dioxide pulse arc welding method in which welding is performed by repeating the base period as one pulse period,
During the peak period, a droplet is formed at the tip of the welding wire by vibrating the peak current,
During the base period, this formed droplet is transferred to the molten pool by short circuit transfer,
This is a carbon dioxide pulse arc welding method.

In the invention of claim 2, the amplitude and vibration period of the oscillating peak current are set to values at which spatter does not scatter from the droplet being formed by suppressing overheating of the droplet.
The carbon dioxide pulsed arc welding method according to claim 1.

In the invention of claim 3, the waveform of the oscillating peak current is a rectangular wave shape.
The carbon dioxide pulse arc welding method according to claim 1 or 2, wherein

In the invention of claim 4, the base period is a period that continues until a short-circuit transition is performed.
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3, wherein:

In the invention of claim 5, the base period is formed from a short-circuit standby period until a short-circuit occurs, and a short-circuit period in which a subsequent droplet transitions to a short-circuit,
Energizing a predetermined first base current during the short-circuit standby period, and energizing a second base current that gradually increases with time from the value of the first base current during the short-circuit period,
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3, wherein:

According to a sixth aspect of the present invention, in the base period, a short-circuit standby period until a short-circuit occurs, a short-circuit period in which a subsequent droplet transitions to a short-circuit, and a short-circuit again occurs after a subsequent arc is re-generated. Formed from a predetermined re-short circuit prevention period to prevent,
During the short-circuit standby period, a predetermined first base current is applied, and during the short-circuit period, a second base current that gradually increases with the passage of time from the value of the first base current is applied, thereby preventing the re-short circuit. During the period, a third base current having a value larger than the value of the first base current is applied.
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3, wherein:

In the invention of claim 7, the base period is formed of a short-circuit standby period until a short-circuit occurs, a short-circuit period in which a subsequent droplet transitions to a short-circuit, and a predetermined delay period following the short-circuit period.
A predetermined first base current is applied during the short-circuit standby period, a second base current that gradually increases with time from the value of the first base current is applied during the short-circuit period, and during the delay period Energizes a predetermined fourth base current equal to or less than the value of the first base current,
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3, wherein:

According to an eighth aspect of the present invention, the base period includes a short-circuit standby period until a short-circuit occurs, a short-circuit period during which a droplet moves to a short-circuit, and a short-circuit again after a subsequent arc is re-generated. Formed from a predetermined re-shorting prevention period followed by a predetermined delay period,
During the short-circuit standby period, a predetermined first base current is applied, and during the short-circuit period, a second base current that gradually increases with the passage of time from the value of the first base current is applied, thereby preventing the re-short circuit. A third base current having a value larger than the value of the first base current is applied during the period, and a predetermined fourth base current less than the first base current is applied during the delay period;
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3, wherein:

In the invention of claim 9, the length of the peak period is changed by arc length control.
The carbon dioxide pulse arc welding method according to any one of claims 1 to 8, wherein:

The invention of claim 10 is such that the arc length control is performed so that an average value of the welding voltage becomes equal to a predetermined welding voltage setting value.
The carbon dioxide pulsed arc welding method according to claim 9.

In the invention of claim 11, the average value of the welding voltage is an average value of the welding voltage for each pulse period.
The carbon dioxide pulse arc welding method according to claim 10, wherein:

According to a twelfth aspect of the present invention, the maximum value during each oscillation period of the peak current increases from the first maximum value as the time of the peak period elapses, and decreases after reaching the second maximum value. Change to the maximum value,
It is a carbon dioxide pulse arc welding method of any one of Claims 1-11 characterized by the above-mentioned.

  According to the present invention, in the carbon dioxide pulse arc welding method using a shielding gas containing carbon dioxide as a main component, a droplet period is substantially desired by providing a peak period and a base period and vibrating a peak current during the peak period. The formed droplets can be short-circuited during the base period. For this reason, since one droplet period and one droplet transfer state can be realized, high-quality welding with less spattering can be achieved. In particular, during high-speed welding in a current region of 200 A or more, the generation of spatter can be suppressed and the bead appearance can be improved as compared with the DC carbon dioxide arc welding method.

It is an electric current / voltage waveform diagram which shows the carbon dioxide pulse arc welding method concerning Embodiment 1 of the present invention. It is a block diagram of the welding power supply for implementing the carbon dioxide pulse arc welding method concerning Embodiment 1 shown in FIG. It is an electric current and voltage waveform diagram which shows the carbon dioxide gas pulse arc welding method which concerns on Embodiment 2 of this invention. It is a block diagram of the welding power supply for implementing the carbon dioxide pulse arc welding method concerning Embodiment 2 shown in FIG. It is a current / voltage waveform diagram of a conventional pulse arc welding method.

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

[Embodiment 1]
FIG. 1 is a current / voltage waveform diagram showing a carbon dioxide pulse arc welding method according to Embodiment 1 of the present invention. FIG. 4A shows the time change of the welding current Iw, and FIG. 4B shows the time change of the welding voltage Vw. The figure shows the case of a carbon dioxide pulse arc welding method using a shielding gas containing carbon dioxide as a main component. Hereinafter, a description will be given with reference to FIG.

  In the carbon dioxide pulse arc welding method according to Embodiment 1 of the present invention, the pulse period Tpb at times t1 to t3 is formed from two periods. The first is the base period Tb from time t1 to t2, and the second is the peak period Tp from time t2 to t3. Therefore, welding is performed repeatedly with the base period Tb and the peak period Tp as one pulse period Tpb. In the base period Tb, the droplet transitions to a short circuit, and the droplet is formed in the peak period Tp. Hereinafter, each period will be described in detail.

(1) Base period Tb (short-circuit transition period)
A droplet is formed during the peak period Tp of the previous period. Then, as shown in FIG. 6A, a first base current Ib1 having a predetermined small current value (about 50 to 150 A) that does not allow the droplet to grow is applied from time t1. The welding voltage Vw becomes a base voltage value Vb as shown in FIG. In this state, the welding wire is fed to the molten pool at a predetermined constant speed, and since the first base current Ib1 is a small current value, the feeding speed becomes faster than the melting speed, and the wire tip Will gradually approach the molten pool. At time t11, when the droplet at the tip of the wire comes into contact with the molten pool and is in a short circuit state, the welding voltage Vw rapidly drops to a short circuit voltage value of about several volts, as shown in FIG. When this short-circuit state is determined by the change in the welding voltage Vw, as shown in FIG. 5A, the second base current (short-circuit current) Ib2 that gradually increases with time from the value of the first base current Ib1. To release the short-circuit state. In the short-circuit period from time t11 to t12, the droplet moves to short-circuit, and the arc is regenerated at time t12. When the arc is regenerated, the welding voltage Vw rapidly increases to an arc voltage value of about several tens of volts as shown in FIG. When the reoccurrence of the arc is determined by the change in the welding voltage Vw, the value is larger than the value of the first base current Ib1 during the predetermined re-short circuit period Th from time t12 to t13 as shown in FIG. The third base current Ib3 having a value is applied. By applying the third base current Ib3, a short circuit is prevented from occurring again immediately after the arc is regenerated. That is, when the arc is regenerated, the wire tip and the molten pool are close to each other, so depending on the welding conditions (type of welding wire, feeding speed, groove shape, welding speed, etc.) Due to vibration, re-short circuit is likely to occur. When the re-short circuit occurs, spatter occurs and the welding state becomes unstable. In order to prevent the occurrence of this re-short circuit, a large third base current Ib3 is energized when the arc is regenerated, thereby strengthening the arc force to the molten pool and pushing down the molten pool, and the wire tip and melt Re-shorting is prevented by increasing the distance to the pond. As the value of the third base current Ib3, the value of the second base current Ib2 at the time of the arc reoccurrence (time t12) may be held. Further, the value of the third base current Ib3 that does not cause re-short circuit according to the welding conditions may be obtained by experiment and set to that value. The setting range of the third base current Ib3 is, for example, about 150 to 300A. The re-shorting prevention period Th is set to a range of about 0.5 to 3 ms. It is desirable to optimize the re-short circuit prevention period Th according to the welding conditions.

  Then, as shown in FIG. 5A, the transition is made to the peak period Tp at the time t2 when the predetermined delay period Td has elapsed from the time t13 when the re-short circuit prevention period Th ends. During the delay period Td from time t13 to time t2, as shown in FIG. 6A, the fourth base current Ib4 which is set in advance below the value of the first base current Ib1 is energized, and FIG. As shown, the welding voltage Vw becomes the base voltage Vb. This delay period Td is set in a range of about 0.5 to 3 ms. The reason for providing the delay period Td is to weaken the arc force to the molten pool and to flatten the molten pool surface by supplying the fourth base current Ib4 having a small current value after the arc is regenerated. Thereby, the spatter from a molten pool when the peak current Ip of a large current value starts energization can be reduced.

  The droplet transfer during the base period Tb will be described as follows. During the previous peak period Tp, the droplets are formed in a substantially constant size as will be described later. Since the first base current Ib1 having a small current value is energized during the short-circuit standby period from the time t1 to the time t11, the lifting force does not act so much on the droplet, and gravity and surface tension act to form a spherical shape. To be shaped. In addition, since a short circuit occurs at time 11 in a state where the first base current Ib1 having a small current value is energized, the occurrence of sputtering when the short circuit occurs is reduced. At the same time, since the droplet contacts the molten pool in a shaped state, it smoothly integrates with the molten pool. Therefore, since the droplet is in a short circuit transition state, the value of the second base current Ib2 during the short circuit period does not need to be increased so much, and the transition is smoothly performed and the arc is regenerated. A small amount of spatter is generated at the time of this arc re-occurrence, but since it is a smooth short-circuit transition, the amount is not so large that it is not a practically problematic level.

Since the short-circuit standby period is a period until the droplet is short-circuited to the molten pool, it is not a constant value but a value that changes every moment depending on the welding state. Similarly, since the short-circuit period is a period from when the droplet is short-circuited to the molten pool until the transition is completed and the arc is regenerated, it is not a constant value but a value that varies depending on the droplet transition state. However, when the welding state is stable, the variation in the short-circuit period is small. The re-short circuit prevention period Th and the delay period Td are predetermined constant values. Therefore, the base period Tb, which is the sum of these periods, is not a constant value but a value that varies depending on the welding state. However, in a stable welding state, the base period Tb can be regarded as a substantially constant value. The base current Ib during the base period Tb is formed from the first base current Ib1 to the fourth base current Ib4. Whether the re-short-circuit prevention period Th and the delay period Td are provided according to the welding conditions can be set. This is because, depending on the welding conditions, providing each period may have an effect of reducing spatter. On the contrary, there are welding conditions in which even if these periods are provided, there is no effect such as reduction of spatter. Therefore, the base period Tb may be formed by selecting one pattern from the following four patterns according to the welding conditions.
(A) Short-circuit standby period + short-circuit period (b) Short-circuit standby period + short-circuit period + re-short-circuit prevention period Th
(C) Short-circuit standby period + short-circuit period + delay period Td
(D) Short-circuit standby period + short-circuit period + re-short-circuit prevention period Th + delay period Td

(2) Peak period Tp (droplet formation period) at times t2 to t3
During the peak period Tp from time t2 to t3, as shown in FIG. 6A, the oscillating peak current Ip is applied, and as shown in FIG. 5B, the welding voltage Vw is the corresponding oscillating peak. The voltage Vp. The oscillation waveform of the peak current Ip is a high peak current HIp during the high peak period HTp shown at time t2 to t21, and is a low peak during the subsequent low peak period LTp from time t21 to t22, as shown in FIG. The current LIp is obtained. The total period of the high peak period HTp and the low peak period LTp is the oscillation period Ts. Further, the difference (HIp−LIp) between the high peak current HIp and the low peak current LIp is the amplitude Ws. Further, the duty Ds = HTp / Ts. Therefore, the peak current Ip vibrates with the amplitude Ws and the vibration period Ts. An example of the range of each value when the welding wire is a steel wire having a diameter of 1.2 mm is as follows. High peak current HIp: 350 to 500 A, amplitude Ws: 200 to 400 A, vibration period Ts: 1.5 to 3.0 ms, duty Ds: 0.5 to 0.75. In the figure, the peak current Ip is illustrated as oscillating in a rectangular wave shape, but may be oscillated in a trapezoidal wave shape, a triangular wave shape, a sine wave shape, a sawtooth wave shape, or the like. The reason for oscillating the peak current Ip is as follows. That is, when the peak current Ip is continuously energized without oscillating, the temperature of the droplet is superheated with the formation of the droplet, and the phenomenon that the gas contained in the droplet expands and the droplet bursts occurs. It comes to occur. When this rupture phenomenon occurs, spatter is scattered from the droplet and formation of the droplet is also inhibited. When the peak current Ip is vibrated with an appropriate amplitude Ws and vibration period Ts, overheating of the droplet can be suppressed and a droplet having a desired size can be formed. The droplet having a desired size is about 1.5 to 2.5 times the diameter of the welding wire. Therefore, the amplitude Ws and the vibration period Ts are set to values at which the spatter does not scatter from the droplet without overheating the droplet. Both values are set to appropriate values according to the material of the welding wire, the diameter, the type of shield gas, the feeding speed, and the like. By this peak period Tp, a droplet having a substantially desired size is formed. The length of the peak period Tp is determined as follows. When the base period Tb is controlled at a constant voltage and the peak period Tp is controlled at a constant current, the peak period Tp is set as a predetermined value. However, the value of the peak period Tp is set to an appropriate value depending on the material of the welding wire, the diameter, the type of shield gas, the feeding speed, and the like. On the other hand, when constant current control is performed for both the base period Tb and the peak period Tp, the peak period Tp is determined by feedback control so that the average value of the welding voltage during the pulse period Tpb becomes equal to a predetermined welding voltage setting value. become. In the former case, since the arc length control is performed by the constant voltage control of the base period Tb, the peak period Tp is set to a predetermined value. On the other hand, in the latter case, the arc length control is performed by making the welding voltage average value of the pulse period Tpb equal to the welding voltage set value.

The droplet transfer in the carbon dioxide pulse arc welding method according to Embodiment 1 of the present invention described above is summarized as follows.
(1) During the peak period Tp, the peak current Ip is oscillated to suppress overheating of the droplet and to prevent spatter from the droplet. For this reason, the droplet of a desired size can be formed stably.
(2) During the base period Tb, the first base current Ib1 having a small current value is energized to guide the droplet at the tip of the welding wire to a short circuit with the molten pool. And a droplet will transfer to a short circuit. Since a short circuit occurs with the first base current Ib1 having a small current value, the occurrence of spatter is small when a short circuit occurs. In addition, since a droplet having a substantially constant size is transferred to a short circuit, the transfer is performed smoothly, and the amount of spatter at the time of arc re-occurrence is not so large as to be a practical problem.
(3) By the operations (1) and (2), one droplet moves in synchronization with each pulse period Tpb. That is, one droplet period and one droplet transfer state are realized, and a stable welding state is obtained. For this reason, even during high-speed welding in a current range of 200 A or more where the welding state tends to be unstable, high-quality welding with less spatter can be performed.

  The numerical example of each parameter in the waveform of FIG. 1 is shown. Welding wire: Steel wire with a diameter of 1.2 mm, average welding current value: 220 A, feeding speed: 7 m / min, first base current Ib1: 100 A during the short-circuit standby period, re-short-circuit prevention period Th: 1 ms, third base current Ib3: 200 A, delay period Td: 1 ms, fourth base current Ib4: 50 A, high peak current value HIp: 450 A, amplitude Ws: 350 A, oscillation period Ts: 2.0 ms, duty Ds: 1.5 / 2.0 = 0.75 and peak period Tp: 7.5 ms. When the peak period Tp is feedback-controlled as described above, this indicates that the welding condition is approximately 7.5 ms.

  FIG. 2 is a block diagram of a welding power source for carrying out the carbon dioxide pulse arc welding method according to Embodiment 1 of the present invention described above with reference to FIG. 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 three-phase 200V as input, performs output control by inverter control according to a current error amplification signal Ei described later, and a welding current Iw and welding voltage Vw suitable for arc welding. Is output. The power supply main circuit PM is not shown in the figure, but includes, for example, a primary rectifier that rectifies commercial power, a capacitor that smoothes the rectified direct current, an inverter circuit that converts the smoothed direct current to high frequency alternating current, and arcs the high frequency alternating current High-frequency transformer that steps down to a voltage suitable for welding, secondary rectifier that rectifies the stepped-down high-frequency alternating current, a reactor that smoothes the rectified direct current, and pulse width modulation control using the current error amplification signal Ei described above as input Based on this result, it comprises a drive circuit for driving the inverter circuit. The welding wire 1 is fed through the welding torch 4 by the rotation of a feeding roll 5 of a wire feeding device (not shown), and an arc 3 is generated between the base metal 2 and the welding wire 1.

  The current detection circuit ID detects the welding current Iw and outputs a welding current detection signal Id. The voltage detection circuit VD detects the welding voltage Vw and outputs a welding voltage detection signal Vd. The short-circuit determination circuit SD receives the welding voltage detection signal Vd as an input, determines a short-circuit state based on the value, and outputs a short-circuit determination signal Sd that becomes a high level. The welding voltage average value calculation circuit VAV receives the welding voltage detection signal Vd as an input, and the welding voltage average value signal Vav = (1), where t is the elapsed time from the start of the base period (time t1 in FIG. 1). / T) · Vd · dt is calculated and output every moment. The welding voltage setting circuit VR outputs a predetermined welding voltage setting signal Vr. The comparison circuit CM receives the welding voltage average value signal Vav and the welding voltage setting signal Vr, and the value of the welding voltage average value signal Vav is equal to or greater than the value of the welding voltage setting signal Vr (Vav ≧ Vr). A pulse period signal Spb that is at a high level for a short time is output. Here, as shown in FIG. 1B, the base voltage Vb during the base period Tb from time t1 to t2 is a relatively small value because the base current Ib has a small current value. The value of the welding voltage setting signal Vr is set to a value larger than the base voltage Vb. As a result, the value of the welding voltage average value signal Vav during the base period Tb is smaller than the value of the welding voltage setting signal Vr. When a short circuit occurs during the base period Tb and the arc is regenerated, the peak period Tp is entered. The peak voltage Vp during the peak period Tp is larger than the value of the welding voltage setting signal Vr because the peak current Ip is an average large value. As a result, during the peak period Tp, the value of the welding voltage average value signal Vav gradually increases. Then, in order to end the peak period Tp when Vav ≧ Vr is reached, the pulse period signal Spb is changed to a high level for a short time. Accordingly, in FIG. 1, the pulse cycle signal Spb is a signal that is at a high level for a short time at time t1 and then at a high level for a short time at time t3. In other words, the base period Tb starts when the pulse period signal Spb becomes a high level for a short time, and the peak period Tp ends and the next base period Tb starts when the pulse period signal Spb becomes a high level for a short time. As a result, the value of the welding voltage average value signal Vav for each pulse period Tpb is always equal to the value of the welding voltage set value Vr, and appropriate arc length control is performed.

  The re-short circuit prevention period setting circuit THR outputs a predetermined re-short circuit prevention period setting signal Thr. The delay period setting circuit TDR outputs a predetermined delay period setting signal Tdr. The period switching control circuit ST receives the re-short circuit prevention period setting signal Thr, the delay period setting signal Tdr, the pulse period signal Spb, and the short circuit determination signal Sd, and the pulse period signal Spb is set to a high level. When the value changes, the value changes to 1 (short-circuit standby period). If the short-circuit determination signal Sd becomes High level (short-circuit state) during this period, the value becomes 2 (short-circuit period), and then the short-circuit determination signal Sd When the Low level (arc generation state) is reached, the value becomes 3 (re-short-circuit prevention period Th) during the period determined by the re-short-circuit prevention period setting signal Thr from that point, and subsequently during the period determined by the delay-period setting signal Tdr. Outputs a period switching control signal St whose value becomes 4 (delay period Td) and changes to 5 (peak period Tp) when the delay period elapses thereafter. That. In FIG. 1, the period switching control signal St is 1 during the short-circuit standby period from time t1 to t2, 2 during the short-circuit period from time t11 to t12, and 3 during the re-short-circuit prevention period Th from time t12 to t13. And becomes 4 during the delay period Td from time t13 to t2, and becomes 5 during the peak period Tp from time t2 to t3.

  The base current setting circuit IBR receives the above-described period switching control signal St. When the period switching control signal St = 1 (short-circuit standby period), the base current setting circuit IBR has a predetermined first base current value Ib1, and the period switching control signal St = In the case of 2 (short circuit period), the second base current value Ib2 gradually increases with the passage of time from the first base current value Ib1, and when the period switching control signal St = 3 (re-short circuit prevention period Th) When the period switching control signal St = 4 (delay period Td), the base current setting signal Ibr which is the predetermined fourth base current value Ib4 is output. Here, the third base current value Ib3 may be set to the second base current value Ib2 at the time when the short-circuit period ends (when St changes from 2 to 3). In this way, the third base current value Ib3 during the re-short-circuit prevention period Th holds the current value when the arc is regenerated. The high peak current setting circuit HIPR outputs a predetermined high peak current setting signal HIpr. The amplitude setting circuit WSR outputs a predetermined amplitude setting signal Wsr. The vibration cycle setting circuit TSR outputs a predetermined vibration cycle setting signal Tsr. The duty setting circuit DSR outputs a predetermined duty setting signal Dsr. The peak current setting circuit IPR receives the high peak current setting signal HIpr, the amplitude setting signal Wsr, the vibration period setting signal Tsr, the duty setting signal Dsr, and the period switching control signal St as inputs. A rectangular wave-shaped peak current setting signal Ipr as shown in FIG. 1 which starts vibration in synchronization with the switching control signal St = 5 (peak period Tp) is output. The switching circuit SW receives the period switching control signal St, the base current setting signal Ibr, and the peak current setting signal Ipr as input, and switches to the a side when the period switching control signal St is 1 to 4, and the switching circuit SW switches to the a side. The base current setting signal Ibr is output as the current control setting signal Icr. When St = 5, the base current setting signal Ibr is switched to the b side and the peak current setting signal Ipr is output as the current control setting signal Icr.

  The current error amplification circuit EI amplifies an error between the current control setting signal Icr and the welding current detection signal Id, and outputs a current error amplification signal Ei. By these blocks, the welding current Iw as described above with reference to FIG.

  According to the first embodiment described above, in the carbon dioxide pulse arc welding method using the shield gas containing carbon dioxide as a main component, the peak period and the base period are provided, and the peak current during the peak period is vibrated to cause the melting. Drops can be formed to approximately the desired size, and the formed droplets can be short-circuited during the base period. For this reason, since one droplet period and one droplet transfer state can be realized, high-quality welding with less spattering can be achieved. In particular, during high-speed welding in a current region of 200 A or more, the generation of spatter can be suppressed and the bead appearance can be improved as compared with the DC carbon dioxide arc welding method.

[Embodiment 2]
The second embodiment of the present invention is different from the first embodiment described above in that the maximum value in each oscillation cycle of the peak current increases from the first maximum value with the lapse of time of the peak period, and the second maximum value. The difference is that it decreases to reach the third maximum value after reaching. That is, in Embodiment 2, the maximum value of the peak current during each vibration cycle changes in a convex shape. On the other hand, in the first embodiment, the maximum value of the peak current during each vibration cycle is a constant value. Hereinafter, the case where the vibration waveform of the peak current is a rectangular wave as in FIG. 1 described above will be described with reference to the drawings.

  FIG. 3 is a current / voltage waveform diagram showing a carbon dioxide pulse arc welding method according to Embodiment 2 of the present invention. FIG. 4A shows the time change of the welding current Iw, and FIG. 4B shows the time change of the welding voltage Vw. This figure corresponds to FIG. 1 described above, and the periods other than the peak period Tp are the same as those in FIG. Hereinafter, the operation during the peak period Tp will be described with reference to FIG.

  In the carbon dioxide pulse arc welding method according to the second embodiment of the present invention, the pulse period Tpb at times t1 to t3 is formed from two periods as in the first embodiment. The first is the base period Tb from time t1 to t2, and the second is the peak period Tp from time t2 to t3. Therefore, welding is performed repeatedly with the base period Tb and the peak period Tp as one pulse period Tpb. In the base period Tb, the droplet transitions to a short circuit, and the droplet is formed in the peak period Tp. Hereinafter, since the operation in the base period Tb is the same, the operation in the peak period Tp will be described in detail.

(21) Peak period Tp (droplet formation period) at times t2 to t3
During the peak period Tp from time t2 to t3, as shown in FIG. 5A, the peak current Ip that vibrates and the maximum value in each vibration period changes in a convex shape is energized. ), The welding voltage Vw becomes the corresponding peak voltage Vp that vibrates. As shown in FIG. 6A, the peak current Ip vibrates in a rectangular wave shape with an amplitude Ws and a vibration period Ts. In the figure, the peak period Tp is formed from about 3.75 periods. In the figure, the vibration period Ts is a constant value as in FIG. 1 described above, but unlike FIG. 1, the amplitude Ws is not a constant value but changes. As shown in FIG. 6A, the first oscillation period Ts (1) includes the high peak period HTp (1) from time t2 to t21 when the high peak current HIp (1) is energized, and the low peak current LIp. (1) is formed from the low peak period LTp (1) at times t21 to t22 when the current is applied. The maximum value during the first vibration cycle Ts (1) is the high peak current HIp (1). The second oscillation period Ts (2) includes a high peak period HTp (2) from time t22 to t23 when the high peak current HIp (2) is energized and a time t23 to t24 when the low peak current LIp (2) is energized. And the low peak period LTp (2). The maximum value in the second vibration cycle Ts (2) is the high peak current HIp (2). The third oscillation period Ts (3) includes a high peak period HTp (3) at times t24 to t25 when the high peak current HIp (3) is energized and times t25 to t26 when the low peak current LIp (3) is energized. Of the low peak period LTp (3). The maximum value in the third vibration cycle Ts (3) is the high peak current HIp (3). The fourth vibration cycle Ts (4) ends in the middle of the cycle, and is formed from the high peak period HTp (4) from time t26 to t3 when the high peak current HIp (4) is energized. The maximum value in the fourth vibration cycle Ts (4) is the high peak current HIp (4).

In the second embodiment, as shown in FIG. 5A, the maximum value (high peak current value) in each vibration cycle is set according to the following magnitude.
HIp (1) <HIp (2) and HIp (2) = HIp (3) and HIp (3)> HIp (4)
Here, when HIp (1) is the first maximum value, HIp (2) = HIp (3) is the second maximum value, and HIp (4) is the third maximum value, during each oscillation period of the peak current Ip The maximum value increases from the first maximum value with the lapse of the peak period Tp, decreases after reaching the second maximum value, and changes to the third maximum value. These first maximum value to third maximum value are set as follows. First, in the same manner as in the first embodiment, the maximum value in each vibration period is set to the same value, and a value at which droplet formation is smoothly performed is obtained by experiment. Using the obtained value as a reference value, the first maximum value is set to a value smaller than the reference value by a predetermined value. The second maximum value is set to a value that is larger than the reference value by a predetermined value. The third maximum value is set to a value smaller than the reference value by a predetermined value. The predetermined value is set to an appropriate value by experiment. As numerical examples of the first maximum value to the third maximum value, HIp (1) = 400A, HIp (2) = HIp (3) = 500A, and HIp (4) = 400A. Since the low peak current value does not change, it is as follows.
LIp (1) = LIp (2) = LIp (3) = LIp (4)
Therefore, the amplitude Ws changes as follows.
Ws (1) <Ws (2) and Ws (2) = Ws (3) and Ws (3)> Ws (4)

  As described above, when the constant current control is performed during the peak period Tp and the constant voltage control is performed during the base period Tb, if the material, diameter, and type of the shielding gas of the welding wire are determined, the peak period Tp is the feeding speed. Is set to a predetermined value according to. On the other hand, even when the peak period Tp and the base period Tb are both controlled at constant current and the length of the peak period Tp is feedback controlled, if the material of the welding wire, the diameter, and the type of shield gas are determined, the steady welding state can be obtained. The peak period Tp is almost a predetermined value corresponding to the feeding speed. Therefore, in any of the above cases, the peak period Tp may be considered to be determined in accordance with the feeding speed within the range of 3 to 6 vibration periods.

A method for setting the high peak current value HIp according to the length of the peak period Tp will be described below.
Case (a): Tp = 3 vibration periods HIp (1) <HIp (2) and HIp (2)> HIp (3)
In this case, the first maximum value = HIp (1), the second maximum value = HIp (2), and the third maximum value = HIp (3).
Case (b): 3 vibration cycles <Tp ≦ 4 vibration cycles (in the case of FIG. 3)
HIp (1) <HIp (2) and HIp (2) = HIp (3) and HIp (3)> HIp (4)
In this case, the first maximum value = HIp (1), the second maximum value = HIp (2) = HIp (3), and the third maximum value = HIp (4).
Case (c): 4 vibration cycles <Tp ≦ 5 vibration cycles HIp (1) <HIp (2) and HIp (2) <HIp (3) and HIp (3)> HIp (4) and HIp (4)> HIp (Five)
In this case, the first maximum value = HIp (1), the second maximum value = HIp (3), and the third maximum value = HIp (5).
Case (d): 5 vibration cycles <Tp ≦ 6 vibration cycles HIp (1) <HIp (2) and HIp (2) <HIp (3) and HIp (3) = HIp (4) and HIp (4)> HIp (5) and HIp (5)> HIp (6)
In this case, the first maximum value = HIp (1), the second maximum value = HIp (3) = HIp (4), and the third maximum value = HIp (6).

Here, the setting method of the high peak current HIp is summarized as follows.
1) When the material of the welding wire, the diameter, and the type of shield gas are determined and the feeding speed is set, the length of the peak period Tp in the steady welding state is calculated from the relational expression obtained in advance by experiments. The calculated peak period Tp is used only for setting the high peak current HIp, and is not used for actually controlling the length of the peak period Tp.
2) One of the above (a) to (d) is selected according to the calculated length of the peak period Tp, and the high peak current value in each cycle is set to a predetermined value.

  As described above, the reason why the maximum value of the peak current during each vibration period is changed to a convex shape is as follows. That is, since the droplet is still small in the early stage of the peak period Tp, if the maximum value of the peak current during the oscillation period is decreased, the lifting force acting on the droplet is weakened and the formation of the droplet becomes smoother. In the middle of the peak period Tp, the maximum value of the peak current during the vibration period is increased to promote the growth of the droplet. In this middle stage, since the droplets are large, the effect of the lifting force is small. Furthermore, at the end of the peak period Tp, by reducing the maximum value of the peak current during the oscillation period, the detachment of the droplets is promoted and the arc force to the molten pool is weakened to reduce the molten pool depression. Thus, the occurrence of a short circuit in the next base period Tb occurs earlier. In this way, the peak current Ip is vibrated, and the maximum value in each vibration period is changed to a convex shape, thereby further facilitating the formation of the droplet. Furthermore, since a short circuit can be generated early in the base period Tb, the base period Tb can be shortened. Thereby, since the peak period Tp can also be shortened, the pulse period can be shortened. Since a droplet moves to one droplet in one pulse cycle, a shorter pulse cycle means a smaller droplet size. As a result, high-speed weldability can be further improved.

  FIG. 4 is a block diagram of a welding power source for carrying out the carbon dioxide pulse arc welding method according to the second embodiment of the present invention described above with reference to FIG. In the figure, the same blocks as those in FIG. In the figure, the high peak current setting circuit HIPR in FIG. 2 is replaced by a second high peak current setting circuit HIPR2 indicated by a broken line, the amplitude setting circuit WSR in FIG. 2 is replaced by a second amplitude setting circuit WSR2 indicated by a broken line, The peak current setting circuit IPR in FIG. 2 is replaced with a second peak current setting circuit IPR2 indicated by a broken line. Hereinafter, these blocks will be described with reference to FIG.

The second high peak current setting circuit HIPR2 selects one of the cases (a) to (d) described above according to the material of the welding wire, the diameter, the type of the shielding gas, and the feeding speed, A high peak current setting signal HIpr formed from a plurality of set values is output. For example, in the case of FIG. 3, since the case (b) is selected, the high peak current setting signal HIpr formed from the predetermined high peak current setting values HIp (1) to HIp (4) is output. . Here, the relationship between the set values is as follows.
HIp (1) <HIp (2) and HIp (2) = HIp (3) and HIp (3)> HIp (4)

The second amplitude setting circuit WSR2 receives the high peak current setting signal HIpr as an input, and an amplitude setting signal Wsr formed from a plurality of amplitude setting values corresponding to the plurality of setting values forming the high peak current setting signal HIpr. Is output. For example, in the case of FIG. 3, an amplitude setting signal Wsr formed from amplitude setting values Ws (1) to Ws (4) determined in advance so that the low peak current values LIp during each vibration period are equal. The Here, the relationship between the set values is as follows.
Ws (1) <Ws (2) and Ws (2) = Ws (3) and Ws (3)> Ws (4)

  The second peak current setting circuit IPR2 receives the high peak current setting signal HIpr, the amplitude setting signal Wsr, the vibration period setting signal Tsr, the duty setting signal Dsr, and the period switching control signal St, and inputs the period switching control signal St. = 5 (Peak period Tp) The oscillation starts synchronously from the time of change, and the peak value setting of a rectangular wave shape in which the maximum value (high peak current value) in each oscillation period changes in a convex shape as shown in FIG. The signal Ipr is output.

  According to the second embodiment described above, in addition to the effects of the first embodiment, the maximum value in each vibration period of the peak current increases from the first maximum value with the lapse of time of the peak period, and the second maximum. By setting so as to decrease and change to the third maximum value after reaching the value, the formation state of the droplet can be made smoother. Furthermore, since a short circuit can be generated early in the base period, the length of the base period can be shortened, and high-speed weldability can be improved.

  In the second embodiment described above, the case where the high peak current value and the amplitude change simultaneously is exemplified, but only the high peak current value may change. In the second embodiment, the case where the vibration waveform of the peak current is a rectangular wave is exemplified, but the vibration may be performed in a trapezoidal wave shape, a triangular wave shape, a sine wave shape, a sawtooth wave shape, or the like.

1 welding wire 2 base material 3 arc 4 welding torch 5 feeding roll EI current error amplification circuit Ei current error amplification signal HIp high peak current HIPR high peak current setting circuit HIpr high peak current setting signal HIPR2 second high peak current setting circuit HTp High peak period Iav Welding current average value Ib Base current Ib1 First base current Ib2 Second base current Ib3 Third base current Ib4 Fourth base current IBR Base current setting circuit Ibr Base current setting signal Icr Current control setting signal ID Current detection circuit Id welding current detection signal Ip peak current IPR peak current setting circuit Ipr peak current setting signal IPR2 second peak current setting circuit Iw welding current LIp low peak current LTp low peak period PM power main circuit Sd short circuit determination circuit Sd short circuit determination signal Spb pulse Periodic signal ST period switching control circuit St period Switching control signal SW switching circuit Tb base period Td delay period TDR delay period setting circuit Tdr delay period setting signal Th re-short circuit prevention period THR re-short circuit prevention period setting circuit Thr re-short circuit prevention period setting signal Tp peak period Tpb pulse period Ts oscillation period TSR Vibration cycle setting circuit Tsr Vibration cycle setting signal VAv Welding voltage average value calculation circuit Vav Welding voltage average value (signal)
Vb Base voltage VD Voltage detection circuit vd Welding voltage detection signal Vp Peak voltage VR Welding voltage setting circuit Vr Welding voltage setting (value / signal)
Vw Welding voltage Ws Amplitude WSR Amplitude setting circuit Wsr Amplitude setting signal WSR2 Second amplitude setting circuit

Claims (12)

A carbon dioxide gas pulse that uses a shielding gas containing carbon dioxide as its main component, feeds the welding wire, and repeats the peak period in which the peak current is applied and the base period in which the base current is supplied as one pulse period. In the arc welding method,
During the peak period, a droplet is formed at the tip of the welding wire by vibrating the peak current with a predetermined amplitude and a predetermined vibration period,
During the base period, this formed droplet is transferred to the molten pool by short circuit transfer,
A carbon dioxide pulse arc welding method characterized by the above. The amplitude and the vibration period are set to values at which spatter does not scatter from the droplet being formed by suppressing overheating of the droplet.
The carbon dioxide pulse arc welding method according to claim 1. The waveform of the oscillating peak current is rectangular.
The carbon dioxide pulse arc welding method according to claim 1 or 2, wherein The base period is a period that continues until a short-circuit transition is performed,
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3. The base period is formed from a short-circuit standby period until a short-circuit occurs, and a short-circuit period in which a subsequent droplet transitions to a short-circuit,
Energizing a predetermined first base current during the short-circuit standby period, and energizing a second base current that gradually increases with time from the value of the first base current during the short-circuit period,
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3. The base period includes a short-circuit standby period until a short-circuit occurs, a short-circuit period in which a droplet subsequently moves to a short-circuit, and a predetermined re-short circuit that prevents a short-circuit from occurring again after a subsequent arc is re-generated. Prevention period, and formed from
During the short-circuit standby period, a predetermined first base current is applied, and during the short-circuit period, a second base current that gradually increases with the passage of time from the value of the first base current is applied, thereby preventing the re-short circuit. During the period, a third base current having a value larger than the value of the first base current is applied.
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3. The base period is formed from a short-circuit standby period until a short-circuit occurs, a short-circuit period in which the subsequent droplet moves to a short-circuit, and a predetermined delay period following the short-circuit period.
A predetermined first base current is applied during the short-circuit standby period, a second base current that gradually increases with time from the value of the first base current is applied during the short-circuit period, and during the delay period Energizes a predetermined fourth base current equal to or less than the value of the first base current,
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3. The base period includes a short-circuit standby period until a short-circuit occurs, a short-circuit period in which a droplet subsequently moves to a short-circuit, and a predetermined re-short circuit that prevents a short-circuit from occurring again after a subsequent arc is re-generated. Formed from a prevention period followed by a predetermined delay period,
During the short-circuit standby period, a predetermined first base current is applied, and during the short-circuit period, a second base current that gradually increases with the passage of time from the value of the first base current is applied, thereby preventing the re-short circuit. A third base current having a value larger than the value of the first base current is applied during the period, and a predetermined fourth base current less than the first base current is applied during the delay period;
The carbon dioxide pulse arc welding method according to any one of claims 1 to 3. The length of the peak period varies depending on arc length control.
The carbon dioxide pulse arc welding method according to any one of claims 1 to 8, wherein: The arc length control is control performed so that the average value of the welding voltage is equal to a predetermined welding voltage setting value.
The carbon dioxide pulse arc welding method according to claim 9. The average value of the welding voltage is an average value of the welding voltage for each pulse period,
The carbon dioxide pulsed arc welding method according to claim 10. A maximum value during each oscillation period of the peak current increases from the first maximum value with the passage of time of the peak period, decreases after reaching the second maximum value, and changes to a third maximum value;
The carbon dioxide pulse arc welding method according to any one of claims 1 to 11, wherein:

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