Arc welding method and arc welding device

Abstract

To secure arc stability in a reverse polarity period, and suppress occurrence of an irregular short circuit.SOLUTION: In a first step, a welding wire W1 is fed at first feeding speed WF1 in a reverse polarity period Tep. In a second step, feeding speed WF of the welding wire W1 is changed to second feeding speed WF2 larger than the first feeding speed WF1, when performing communication from the reverse polarity period Tep to a positive polarity period Ten. In a third step, the welding wire W1 is fed at the second feeding speed WF2, in the positive polarity period Ten. In a fourth step, the feeding speed WF of the welding wire W1 is changed to the first feeding speed WF1, before performing communication from the positive polarity period Ten to the reverse polarity period Tep.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an arc welding method and an arc welding apparatus. [Background technology]

[0002] Patent Document 1 discloses a feed control method for consumable electrode AC arc welding in which welding is performed by alternately switching the voltage applied to the arc between reverse polarity (positive electrode polarity) and positive polarity (negative electrode polarity). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5090765 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while the welding wire has a high melting efficiency during the positive polarity period, the welding wire melting characteristics tend to be inferior during the reverse polarity period compared to the positive polarity period. Therefore, it is preferable to increase the welding wire feed rate during the positive polarity period to increase the amount of welding wire deposited, and to decrease the welding wire feed rate during the reverse polarity period.

[0005] In the invention of Patent Document 1, the welding wire feed speed is changed simultaneously with the commutation from the reverse polarity period to the positive polarity period and simultaneously with the commutation from the positive polarity period to the reverse polarity period.

[0006] However, in the invention of Patent Document 1, immediately after the changeover from the positive polarity period to the reverse polarity period, the welding wire feed speed is maintained at a high speed, and excessively grown droplets are fed at a high speed, which may cause irregular short circuits, resulting in an unstable arc and increased spatter.

[0007] The present invention has been made in view of the above points, and an object of the present invention is to ensure arc stability during the reverse polarity period and to prevent irregular short circuits from occurring. [Means for solving the problem]

[0008] A first invention is an arc welding method for welding by feeding a welding wire, which is a consumable electrode, toward a base metal, and passing a welding current through the welding wire and the base metal so that reverse polarity periods in which the welding wire is positive and the base metal is negative and positive polarity periods in which the welding wire is negative and the base metal is positive are alternately repeated, the method comprising: a first step of feeding the welding wire at a first feed rate during the reverse polarity period; a second step of changing the feed rate of the welding wire to a second feed rate higher than the first feed rate when commuting from the reverse polarity period to the positive polarity period; a third step of feeding the welding wire at the second feed rate during the positive polarity period; and a fourth step of changing the feed rate of the welding wire to the first feed rate before commuting from the positive polarity period to the reverse polarity period.

[0009] In the first aspect of the present invention, the welding wire feed rate is increased during the positive polarity period when the welding wire melting efficiency is high, thereby increasing the amount of welding wire deposited and achieving high-deposition AC welding.

[0010] Furthermore, by reducing the welding wire feed rate before commuting to the reverse polarity period in which the welding wire has inferior melting characteristics compared to the positive polarity period, arc stability can be ensured during the reverse polarity period and irregular short circuits can be prevented from occurring.

[0011] A second aspect of the present invention is the arc welding method of the first aspect of the present invention, wherein in the fourth step, the feed speed of the welding wire is abruptly changed from the second feed speed to the first feed speed.

[0012] In the second aspect of the present invention, the feeding speed of the welding wire is suddenly reduced, thereby reducing the risk of short circuiting during the reverse polarity period and suppressing the generation of spatter.

[0013] A third invention is the arc welding method of the first invention, wherein the fourth step includes a fifth step of changing the feeding speed of the welding wire from the second feeding speed to a third feeding speed that is smaller than the second feeding speed and larger than the first feeding speed, and feeding the welding wire at the third feeding speed, and a sixth step of changing the feeding speed of the welding wire from the third feeding speed to the first feeding speed after the fifth step.

[0014] In the third invention, by gradually reducing the welding wire feed speed from the second feed speed to the third feed speed and then to the first feed speed, the amount of welding wire fed can be increased compared to when the feed speed is suddenly reduced from the second feed speed to the first feed speed, and the amount of welding wire deposited can be further increased.

[0015] A fourth aspect of the present invention is the arc welding method of the first aspect, wherein in the fourth step, the feed speed of the welding wire is changed so as to gradually decrease from the second feed speed to the first feed speed.

[0016] In the fourth aspect of the present invention, the welding wire feed speed is gradually reduced, thereby improving the stability of the arc compared to when the welding wire feed speed is reduced abruptly.

[0017] A fifth invention is the arc welding method of the first invention, wherein the fourth step includes a seventh step of changing the feeding speed of the welding wire from the second feeding speed to a fourth feeding speed that is slower than the first feeding speed and feeding the welding wire at the fourth feeding speed, and an eighth step of changing the feeding speed of the welding wire from the fourth feeding speed to the first feeding speed after the seventh step.

[0018] In the fifth aspect of the present invention, the feeding speed of the welding wire is temporarily reduced to below the first feeding speed, thereby further reducing the risk of short circuiting and suppressing the generation of spatter.

[0019] A sixth invention is an arc welding apparatus for welding by generating an arc between a welding wire which is a consumable electrode and a base metal, the apparatus comprising: a power conversion unit which applies a welding current between the welding wire and the base metal so that a reverse polarity period in which the welding wire is a positive electrode and the base metal is a negative electrode and a positive polarity period in which the welding wire is a negative electrode and the base metal is a positive electrode are alternately repeated; a wire feeding unit which feeds the welding wire toward the base metal; and a control unit which controls the operation of the wire feeding unit to change the feeding speed of the welding wire, The control unit performs a first operation of feeding the welding wire at a first feeding speed during the reverse polarity period, a second operation of changing the feeding speed of the welding wire to a second feeding speed higher than the first feeding speed when commuting from the reverse polarity period to the positive polarity period, a third operation of feeding the welding wire at the second feeding speed during the positive polarity period, and a fourth operation of changing the feeding speed of the welding wire to the first feeding speed before commuting from the positive polarity period to the reverse polarity period.

[0020] In the sixth aspect of the present invention, the welding wire feed rate is increased during the positive polarity period when the welding wire melting efficiency is high, thereby increasing the amount of welding wire deposited and achieving high-deposition AC welding.

[0021] Furthermore, by reducing the welding wire feed rate before commuting to the reverse polarity period in which the welding wire has inferior melting characteristics compared to the positive polarity period, arc stability can be ensured during the reverse polarity period, and irregular short circuits can be prevented from occurring. [Effects of the Invention]

[0022] According to the present invention, arc stability can be ensured during the reverse polarity period, and irregular short circuits can be prevented from occurring. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram of an arc welding device according to a first embodiment of the present invention. [Figure 2] 4A and 4B are diagrams showing waveforms of a welding current and a welding wire feed speed; [Figure 3] 10A and 10B are diagrams showing waveforms of a welding current and a welding wire feed rate in the second embodiment. [Figure 4] 10A and 10B are diagrams showing waveforms of a welding current and a welding wire feed rate in the third embodiment. [Figure 5] 10A and 10B are diagrams showing waveforms of a welding current and a welding wire feed rate in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0025] First Embodiment As shown in FIG. 1, an arc welding apparatus 1 welds a base metal B1 by generating an arc A1 between a welding wire W1, which is a consumable electrode, and the base metal B1.

[0026] The arc welding device 1 includes a welding unit 10, a wire feeder 21, a welding torch 22, and a setting unit 25.

[0027] Wire feeder 21 feeds welding wire W1 toward base material B1. Specifically, wire feeder 21 feeds welding wire W1 to welding torch 22. Welding torch 22 holds welding wire W1 so that welding wire W1 fed from wire feeder 21 and base material B1 face each other.

[0028] Welding torch 22 has a welding tip 22a. Welding tip 22a supplies power from welding unit 10 to welding wire W1. Wire feeder 21 is provided with a feed speed detector (not shown) that detects the feed speed WF of welding wire W1. Welding torch 22 is held by a robot (not shown). A detection signal indicating the feed speed WF of welding wire W1 detected by the feed speed detector is transmitted to controller 14. The robot moves welding torch 22 at a predetermined welding speed so as to follow a predetermined welding target area on base material B1.

[0029] The setting unit 25 is used to set welding conditions including a welding current and a welding voltage. Specifically, the setting unit 25 sets a set welding current for welding, a set welding voltage for welding, a feed speed of the welding wire W1, a type of shielding gas, a material of the welding wire W1, a diameter of the welding wire W1, a pulse welding period, a number of pulse outputs, etc.

[0030] Welding unit 10 includes power conversion unit 11, welding current detection unit 12, welding voltage detection unit 13, and control unit 14.

[0031] The power conversion unit 11 is electrically connected to a power source S1. The power conversion unit 11 generates a welding voltage V suitable for welding using power supplied from the power source S1. The power conversion unit 11 is electrically connected to a welding wire W1 via a welding tip 22a of a welding torch 22. The power conversion unit 11 is electrically connected to a base material B1. The power conversion unit 11 applies the welding voltage V between the welding wire W1 and the base material B1, thereby causing a welding current I to flow through the welding wire W1 and the base material B1.

[0032] The power conversion unit 11 includes a first rectification unit 101, a first switching unit 102, a transformer 103, a second rectification unit 104, a reactor 105, and a second switching unit 106.

[0033] First rectifier 101 rectifies the output of power source S1. First switching unit 102 adjusts the output of first rectifier 101 by switching operation. Transformer 103 converts the output of first switching unit 102 into an output suitable for welding.

[0034] Second rectifier 104 rectifies the output of transformer 103. Reactor 105 is connected in series with second rectifier 104 and smoothes the output of second rectifier 104. Second switching unit 106 adjusts the output of reactor 105 by switching operation. The output of second switching unit 106 is supplied to welding wire W1 and base material B1 via welding tip 22a of welding torch 22.

[0035] As a result, a welding voltage V is applied between the welding wire W1 and the base metal B1, and a welding current I flows through the welding wire W1 and the base metal B1. As will be described in detail later, the power conversion unit 11 flows the welding current I between the welding wire W1 and the base metal B1 so that a reverse polarity period Tep, in which the welding wire W1 is positive and the base metal B1 is negative, and a positive polarity period Ten, in which the welding wire W1 is negative and the base metal B1 is positive, are alternately repeated.

[0036] Welding current detection unit 12 detects welding current I. Welding voltage detection unit 13 detects welding voltage V. A detection signal indicating the welding current I detected by welding current detection unit 12 and a detection signal indicating the welding voltage V detected by welding voltage detection unit 13 are transmitted to control unit 14.

[0037] Control unit 14 transmits signals between each part of welding unit 10 and devices external to welding unit 10. In the example shown in Fig. 1, the parts of welding unit 10 that transmit signals with control unit 14 are first switching unit 102, second switching unit 106, welding current detection unit 12, and welding voltage detection unit 13. The devices external to welding unit 10 that transmit signals with control unit 14 are wire feeder 21 and setting unit 25.

[0038] Control unit 14 controls each part of welding unit 10 and devices external to welding unit 10 based on signals transmitted from each part of welding unit 10 and devices external to welding unit 10 .

[0039] Control unit 14 controls the operation of wire feeder 21 to change the feed speed WF of welding wire W1. Specifically, control unit 14 controls the feed speed of welding wire W1 in wire feeder 21 in accordance with the set current of welding current I set by setting unit 25. Here, feed speed WF and welding current I are correlated with each other. More specifically, an average welding speed (also referred to as a feed amount) as a moving average and an average welding current (also referred to as a set current) which is an average current as a moving average are correlated with each other.

[0040] Control unit 14 controls first switching unit 102 and second switching unit 106 of power conversion unit 11, wire feeder 21, and a robot (not shown) that holds welding torch 22.

[0041] The control unit 14 is configured by, for example, a processor and a memory electrically connected to the processor. The memory stores programs and information for operating the processor.

[0042] <Method for controlling arc welding equipment> Next, we will explain the operation of the arc welding apparatus 1. The arc welding apparatus 1 supplies a shielding gas from a gas supply port (not shown) to shield the welding point of the base metal B1 from the outside air, while supplying a current between the welding wire W1 and the base metal B1.

[0043] This generates an arc A1 between the welding wire W1 and the base metal B1, and the heat of the arc A1 melts the tip of the welding wire W1 and part of the base metal B1. The melted welding wire W1 turns into molten droplets that drip onto the base metal B1 and form a molten pool together with the part of the base metal B1 that has melted due to the heat of the arc A1.

[0044] The welding torch 22 moves in the welding direction while performing, for example, a spiral weaving motion relative to the base material B1. A bead is formed on the base material B1 as the welding torch 22 moves, and the base material B1 is welded.

[0045] 2 is a diagram showing the waveform of the welding current and the waveform of the welding wire feed speed. In Fig. 2, the vertical axis represents the welding current I and the feed speed WF, and the horizontal axis represents time. In pulse welding, the welding current I is set to, for example, 200 A.

[0046] The arc welding device 1 is a consumable electrode type AC pulse arc welder. The welding current I is controlled so that a reverse polarity period Tep and a positive polarity period Ten are alternately repeated.

[0047] The arc welding device 1 sets the feed speed WF of the welding wire W1 based on the magnitude of the set welding current I. Various pulse parameters that configure the AC pulse waveform are set based on this feed speed WF.

[0048] Here, the pulse parameters include the peak current value Ip, base current value Ib, peak current period Tp, base current period Tb, positive polarity period Ten, and positive polarity current value Ien in the positive polarity period Ten, as shown in FIG.

[0049] The period from time t1 to time t3 is the reverse polarity period Tep of the reverse polarity region EP(+). During the reverse polarity period Tep, the welding current I is controlled so that the welding wire W1 serves as the positive electrode and the base metal B1 serves as the negative electrode.

[0050] In the reverse polarity period Tep, a first step is performed in which the welding wire W1 is fed at a first feed speed WF1. Specifically, the control unit 14 performs a first operation in which the welding wire W1 is fed at the first feed speed WF1 in the reverse polarity period Tep by changing the feed speed WF of the wire feeder 21.

[0051] At time t1, the welding current I changes to a peak current value Ip. The period from time t1 to time t2 is a peak current period Tp. During the peak current period Tp, the welding current I is maintained at the peak current value Ip.

[0052] At time t2, the absolute value of the welding current I changes sharply from the peak current value Ip to the base current value Ib. The period from time t2 to time t3 is the base current period Tb. During the base current period Tb, the welding current I is maintained at the base current value Ib.

[0053] At time t3, the reverse polarity period Tep of the reverse polarity region EP(+) is commutated to the positive polarity period Ten of the positive polarity region EN(-).

[0054] When the polarity is commutated from the reverse polarity period Tep to the positive polarity period Ten, a second step is performed in which the feed speed WF of the welding wire W1 is changed to a second feed speed WF2 that is higher than the first feed speed WF1. Specifically, by changing the feed speed WF of the wire feeder 21, the control unit 14 performs a second operation in which the feed speed WF of the welding wire W1 is changed to the second feed speed WF2 that is higher than the first feed speed WF1 when the polarity is commutated from the reverse polarity period Tep to the positive polarity period Ten.

[0055] The period from time t3 to time t5 is a positive period Ten of the positive region EN(-). During the positive period Ten, the welding current I is controlled so that the welding wire W1 serves as the negative electrode and the base metal B1 serves as the positive electrode. During the positive period Ten, the welding current I is maintained at the positive current value Ien.

[0056] In the positive polarity period Ten, a third step is performed in which the welding wire W1 is fed at the second feed speed WF2. Specifically, the control unit 14 controls the feed speed WF of the welding wire W1 to perform a third operation in which the welding wire W1 is fed at the second feed speed WF2 in the positive polarity period Ten.

[0057] 2, at time t5, the positive polarity period Ten in the positive polarity region EN(-) is commutated to the reverse polarity period Tep in the reverse polarity region EP(+). During the positive polarity period Ten, the feed rate of the welding wire W1 is set to the second feed rate WF2, and the feed rate of the welding wire W1 is increased to increase the deposition rate.

[0058] However, for example, if the feed speed WF of the welding wire W1 is changed from the second feed speed WF2 to the first feed speed WF1 at the same time as the transition from the positive polarity period Ten to the reverse polarity period Tep, the feed speed WF of the welding wire W1 will be maintained at a high level immediately after the transition from the positive polarity period Ten to the reverse polarity period Tep, and excessively large droplets will be fed at a high speed, which may cause irregular short circuits, destabilize the arc, and increase spatter.

[0059] Therefore, in this embodiment, the feed speed WF of the welding wire W1 is changed at time t4, which is a predetermined time before time t5 when the positive polarity period Ten is commutated to the reverse polarity period Tep. For example, if the positive polarity period Ten is 1000 μsec to 2000 μsec, the predetermined time between time t4 and time t5 may be about 100 μsec to 200 μsec.

[0060] At time t4 before time t5 when the positive polarity period Ten is commutated to the reverse polarity period Tep, a fourth step is performed in which the feed speed of the welding wire W1 is changed to a first feed speed WF1. Specifically, control unit 14 changes the feed speed WF of wire feeder 21, and performs a fourth operation in which the feed speed of the welding wire W1 is changed to the first feed speed WF1 at time t4.

[0061] In the fourth step, the feed speed WF of the welding wire W1 is abruptly changed from the second feed speed WF2 to the first feed speed WF1. This reduces the risk of short circuiting during the reverse polarity period Tep and suppresses spatter. After the fourth step, the welding wire W1 is fed at the first feed speed WF1 during the period from time t4 to time t5.

[0062] By repeating steps 1 to 4, the arc welding device 1 generates an arc A1 between the welding wire W1 and the base material B1, and the heat of the arc A1 forms a molten droplet at the tip of the welding wire W1 and melts a portion of the base material B1.

[0063] The droplets formed at the tip of the welding wire W1 are transferred from the tip of the welding wire W1 to the base metal B1 by droplet transfer and adhere to it, forming a molten pool on the base metal B1. In this way, the droplets are transferred without short-circuiting between the welding wire W1 and the base metal B1, and an arc A1 is generated successively by the peak current and the base current, and the droplets formed at the tip of the welding wire W1 detach in the air from the tip of the welding wire W1 and transfer to the base metal B1 so that one droplet is transferred to the base metal B1 for each pulse of one peak current, i.e., one drop per pulse.

[0064] -Effects of the First Embodiment- According to the arc welding apparatus 1 of the first embodiment, by increasing the feed speed of the welding wire W1 during the positive polarity period Ten in which the melting efficiency of the welding wire W1 is high, the deposition amount of the welding wire W1 can be increased, thereby achieving high deposition AC welding.

[0065] In addition, by reducing the feed rate of the welding wire W1 before commuting to the reverse polarity period Tep, in which the melting characteristics of the welding wire W1 are inferior to those of the positive polarity period Ten, arc stability in the reverse polarity period Tep can be ensured and irregular short circuits can be prevented from occurring.

[0066] Furthermore, by sharply reducing the feed speed WF of the welding wire W1 from the second feed speed WF2 to the first feed speed WF1, the risk of a short circuit occurring during the reverse polarity period Tep can be reduced, and the occurrence of spatter can be suppressed.

[0067] Second Embodiment Hereinafter, the same parts as those in the first embodiment will be denoted by the same reference numerals, and only the differences will be described.

[0068] 3, a fourth step is performed to change the feed speed WF of the welding wire W1 to the first feed speed WF1 before time t5 when the positive polarity period Ten is commutated to the reverse polarity period Tep. The fourth step includes a fifth step performed in the period from time t4' before time t4 to time t4, and a sixth step performed in the period from time t4 to time t5.

[0069] In the fifth step, the feed speed WF of the welding wire W1 is changed from the second feed speed WF2 to a third feed speed WF3 that is smaller than the second feed speed WF2 and larger than the first feed speed WF1, and the welding wire W1 is fed at the third feed speed WF3.

[0070] In the sixth step, after the fifth step, the feed speed WF of the welding wire W1 is changed from the third feed speed WF3 to the first feed speed WF1, and the welding wire W1 is fed at the first feed speed WF1.

[0071] In this way, by gradually reducing the feed speed WF of the welding wire W1 from the second feed speed WF2 to the third feed speed WF3 and then to the first feed speed WF1 before the time t5 at which the positive polarity period Ten is commutated to the reverse polarity period Tep, the feed amount of the welding wire W1 can be increased compared to when the feed speed is abruptly reduced from the second feed speed WF2 to the first feed speed WF1, and the deposition amount of the welding wire W1 can be further increased.

[0072] Third Embodiment As shown in FIG. 4, a fourth step is performed to change the feed speed WF of the welding wire W1 to the first feed speed WF1 before time t5 when the positive polarity period Ten is commutated to the reverse polarity period Tep.

[0073] In the fourth step, the feed speed WF of the welding wire W1 is changed so as to gradually decrease from the second feed speed WF2 to the first feed speed WF1. In the example shown in Fig. 4, the waveform of the feed speed WF of the welding wire W1 slopes obliquely downward from time t4 to time t5.

[0074] By gradually decreasing the feed speed WF of the welding wire W1 in this manner, the stability of the arc is improved compared to when the feed speed WF of the welding wire W1 is suddenly decreased.

[0075] Fourth Embodiment As shown in FIG. 5, a fourth step of changing the feed speed WF of the welding wire W1 to the first feed speed WF1 is performed before time t5 when the positive polarity period Ten is commutated to the reverse polarity period Tep.

[0076] The fourth step includes a seventh step performed in the period from time t4', which is before time t4, to time t4, and an eighth step performed in the period from time t4 to time t5.

[0077] In the seventh step, the feeding speed WF of the welding wire W1 is changed from the second feeding speed WF2 to a fourth feeding speed WF4 that is slower than the first feeding speed WF1, and the welding wire W1 is fed at the fourth feeding speed WF4.

[0078] In the eighth step, after the seventh step, the feed speed WF of the welding wire W1 is changed from the fourth feed speed WF4 to the first feed speed WF1.

[0079] In this way, by temporarily lowering the feed speed WF of the welding wire W1 to below the first feed speed WF1, the risk of short circuiting can be further reduced and the occurrence of spatter can be suppressed. [Industrial Applicability]

[0080] As described above, the present invention provides highly practical effects of ensuring arc stability during the reverse polarity period and suppressing the occurrence of irregular short circuits, and is therefore extremely useful and has high industrial applicability. [Explanation of symbols]

[0081] 1. Arc welding equipment 11 Power conversion section 14 Control Unit 21 Wire feeding section A1 アーク B1 base material Tep during reverse polarity period Ten positive polarity period W1 Welding ワイヤ WF1 First Place Awarded to Speed WF2, second place given to speed. WF3, the third gift to speed. WF4, the 4th gift to speed.

Claims

1. An arc welding method for welding by generating an arc between the welding wire and the base metal, comprising: feeding a welding wire that is a consumable electrode toward a base metal; and flowing a welding current through the welding wire and the base metal such that a reverse polarity period in which the welding wire is a positive electrode and the base metal is a negative electrode and a positive polarity period in which the welding wire is a negative electrode and the base metal is a positive electrode are alternately repeated; a first step of feeding the welding wire at a first feed rate during the reverse polarity period; a second step of changing a feed speed of the welding wire to a second feed speed that is higher than the first feed speed when commutating from the reverse polarity period to the positive polarity period; a third step of feeding the welding wire at the second feed speed during the positive polarity period; and a fourth step of changing the feed speed of the welding wire to the first feed speed before a time point at which the positive polarity period is commutated to the reverse polarity period. Arc welding method.

2. The arc welding method of claim 1, In the fourth step, the feeding speed of the welding wire is abruptly changed from the second feeding speed to the first feeding speed. Arc welding method.

3. The arc welding method of claim 1, The fourth step is a fifth step of changing a feed speed of the welding wire from the second feed speed to a third feed speed that is smaller than the second feed speed and larger than the first feed speed, and feeding the welding wire at the third feed speed; and a sixth step of changing the feed speed of the welding wire from the third feed speed to the first feed speed after the fifth step. Arc welding method.

4. The arc welding method of claim 1, In the fourth step, the feeding speed of the welding wire is changed so as to gradually decrease from the second feeding speed to the first feeding speed. Arc welding method.

5. The arc welding method of claim 1, The fourth step is a seventh step of changing a feed speed of the welding wire from the second feed speed to a fourth feed speed that is slower than the first feed speed, and feeding the welding wire at the fourth feed speed; and an eighth step, after the seventh step, of changing the feed speed of the welding wire from the fourth feed speed to the first feed speed. Arc welding method.

6. An arc welding device that generates an arc between a welding wire, which is a consumable electrode, and a base metal to weld, a power conversion unit that flows a welding current between the welding wire and the base metal so that a reverse polarity period in which the welding wire is a positive electrode and the base metal is a negative electrode and a positive polarity period in which the welding wire is a negative electrode and the base metal is a positive electrode are alternately repeated; a wire feeder that feeds the welding wire toward the base material; a control unit that controls the operation of the wire feed unit to change the feed speed of the welding wire, The control unit a first operation of feeding the welding wire at a first feed rate during the reverse polarity period; a second operation of changing a feed speed of the welding wire to a second feed speed that is higher than the first feed speed when commutating from the reverse polarity period to the positive polarity period; a third operation of feeding the welding wire at the second feed speed during the positive polarity period; a fourth operation of changing the feed speed of the welding wire to the first feed speed before a time point at which the positive polarity period is commutated to the reverse polarity period. Arc welding equipment.

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