Arc-welding method and arc-welding device

Abstract

To adjust a penetration depth without changing a mean current with respect to arc-welding.MEANS FOR SOLVING THE PROBLEM: An arc-welding method supplies a welding-current I between a work-piece W and a welding wire 13 to generate arc, thereby performing welding. The welding-current I is configured from pulse waves in which a base current IB and a peak current IP are alternately repeated periodically. The base current IB and the peak current IP are changed according to a base-peak function which becomes such a function that the peak current IP becomes a function of the base current IB while keeping a mean current IA per one cycle in the welding-current I constant.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] As shown in Patent Document 1, in arc welding, a welding current is generally supplied between an object to be welded and an electrode to generate an arc, and welding is performed. The welding current is composed of a pulse wave in which a base current and a peak current are periodically repeated alternately.

[0003] When adjusting the penetration depth into the workpiece in arc welding, the amount of heat input into the workpiece is usually changed by increasing or decreasing the average current per cycle (set current) of the welding current. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-019564 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when trying to increase or decrease the average current to adjust the penetration depth, it is necessary to change the set current and set voltage of the arc welding equipment, which is troublesome. In addition, since changing the set current and set voltage also changes the amount of heat input, it will affect the distortion of the work (welded object), especially when these conditions are adjusted to be high.

[0006] The present disclosure has been made in consideration of the above points, and an object of the present disclosure is to adjust the penetration depth in arc welding without changing the average current. [Means for solving the problem]

[0007] The arc welding method according to the present disclosure is an arc welding method for performing welding by supplying a welding current between an object to be welded and an electrode to generate an arc, the welding current being constituted by a pulse wave in which a base current and a peak current are periodically and alternately repeated, and the base current and the peak current are changed in accordance with a base-peak function in which one of the base current and the peak current is a function of the other while keeping an average current per cycle of the welding current constant. The arc welding apparatus according to the present disclosure is an arc welding apparatus that performs welding by supplying a welding current between an object to be welded and an electrode to generate an arc, wherein the welding current is composed of a pulse wave in which a base current and a peak current are repeated alternately in a periodic manner, and while keeping the average current per period of the welding current constant, the base current and the peak current are changed according to a base-peak function in which one of the base current and the peak current is a function of the other. Effect of the Invention

[0008] According to the present disclosure, for arc welding, the penetration depth can be adjusted without changing the average current. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows an arc welding apparatus. [Diagram 2] FIG. 2 shows the arc length. [Diagram 3] Figure 3 shows the penetration depth. [Figure 4] FIG. 4 shows the change in welding current over time. [Diagram 5] FIG. 5 shows the base-peak function in the first embodiment. [Figure 6] FIG. 6 shows a second embodiment. [Figure 7] FIG. 7 shows a third embodiment. [Figure 8] FIG. 8 shows a flow chart for adjusting the penetration depth. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its application, or its uses.

[0011] (Arc welding equipment) An arc welding method will be described. The arc welding method is performed by an arc welding apparatus 1. FIG.

[0012] The arc welding device 1 performs an arc welding method. In the arc welding method, a welding current I is supplied between a workpiece W as an object to be welded and a welding wire 13 as an electrode to generate an arc A, and welding is performed while supplying a shielding gas S around the arc A. The workpiece W is a metal. In this example, the arc welding device 1 performs MIG (Metal Inert Gas) welding.

[0013] An arc A is generated between the workpiece W and the welding wire 13. The welding wire (electrode wire) 13 is a metal used as a filler material in arc welding. The welding wire 13 is held by a torch (not shown). As the torch moves at a predetermined speed, the welding wire 13 also moves at the same speed in the welding direction along a predetermined welding section.

[0014] Arc welding apparatus 1 includes a main transformer 2, a primary side rectifier 3, a switching unit 4, a DCL (reactor) 5, a secondary side rectifier 6, a welding current detector 7, a welding voltage detector 8, a control switcher 9, an output controller 10, a wire feed speed controller 11, a welding tip 12, a welding wire 13, a nozzle 14, a wire feeder 16, and a welding condition setting unit 17. Arc welding apparatus 1 also includes a robot controller (not shown) that controls the operation of a robot (not shown) that holds a torch (not shown).

[0015] The primary side rectifier 3 rectifies the input voltage input from an input power source (three-phase AC power source) 15 external to the arc welding device 1. The switching unit 4 controls the output of the primary side rectifier 3 to an output suitable for welding. The main transformer 2 converts the output of the switching unit 4 to an output suitable for welding.

[0016] Secondary side rectifier 6 rectifies the output of main transformer 2. DCL (reactor) 5 smoothes the output of secondary side rectifier 6 to a current suitable for welding. Welding current detector 7 detects welding current I flowing through welding wire 13. Welding voltage detector 8 detects welding voltage applied between welding wire 13 and workpiece W.

[0017] The control switching unit 9, the output control unit 10, the wire feed speed control unit 11 and the welding condition setting unit 17 are composed of one or more CPUs (Central Processing Units) or one or more MCUs (Micro Control Units), and are also referred to as controllers.

[0018] The control switching unit 9 outputs a signal for short circuit welding control or pulse welding control to the output control unit 10 based on the determination by the welding voltage detection unit 8 of whether the welding voltage detection unit 8 is in a short circuit state or an arc state.

[0019] Wire feeder 16 feeds welding wire 13 toward workpiece W. Wire feed speed controller 11 controls the feed speed of welding wire 13. Welding condition setting unit 17 sets welding conditions.

[0020] The output control unit 10 outputs a control signal to the switching unit 4 to control the welding output. The output control unit 10 controls the welding current I so that it becomes an average current IA. The output control unit 10 sets the welding current I to the average current IA. The average current IA is also called a set current. The average current IA is a moving average value of the welding current I over a predetermined period. Specifically, the average current IA is an average value per one period T of the pulsed welding current I described later.

[0021] The arc welding device 1 supplies a welding current I to a welding wire 13 via a welding tip 12. The arc welding device 1 supplies the welding current I between a workpiece W and the welding wire 13 to generate an arc A.

[0022] The nozzle 14 surrounds the periphery of the welding tip 12. The shielding gas S supplied from a shielding gas supply unit (not shown) flows between the nozzle 14 and the welding tip 12 and is sprayed toward the workpiece W. This causes the shielding gas S to be supplied to the periphery of the arc A. The shielding gas S is composed of, for example, 100% argon. In this case, the shielding gas S does not contain any elements other than argon (for example, helium, oxygen, carbon dioxide, etc.).

[0023] In this manner, the arc welding device 1 (arc welding method) performs welding by supplying a welding current I between the workpiece W and the welding wire 13 to generate an arc A. The arc welding device 1 (arc welding method) performs welding while supplying a shielding gas S, for example, 100% argon, around the arc A.

[0024] (Arc length) 2 shows the arc length L. The arc length L is the distance between both ends of the arc between the tip 13a of the welding wire 13 and the surface Wa of the workpiece W when performing arc welding. In this example, the arc length L is indicated by the relative position of the tip 13a of the welding wire 13 with respect to the surface Wa of the workpiece W. The inside side of the workpiece W with respect to the surface Wa of the workpiece W (the lower side in FIG. 2, the side opposite the welding tip 12) is set as negative, and the side opposite the inside side of the workpiece W with respect to the surface Wa of the workpiece W (the upper side in FIG. 2, the welding tip 12 side) is set as positive.

[0025] When the arc length L is negative (see the thick two-dot chain line), buried arc welding is performed in which the tip 13a of the welding wire 13 penetrates (is buried) inside the workpiece W. When the arc length L is positive, welding is performed in a state in which the tip 13a of the welding wire 13 and the workpiece W are spaced apart from each other.

[0026] The heat of the arc A melts the workpiece W and the welding wire 13, forming a molten pool Wb.

[0027] It is preferable that the arc length L be within ±2 mm with respect to the surface Wa of the workpiece W.

[0028] The welding wire 13 moves relatively at a moving speed V along the direction in which the surface Wa of the workpiece W extends (the left-right direction in FIG. 2).

[0029] (Penetration depth) 3 shows a cross section of the weld bead in the width direction, and indicates the penetration depth (amount of penetration) U. The penetration depth U is indicated by the distance between the apex (bottom end) Wc1 of the molten zone Wc, which is the portion of the workpiece W that has been melted by welding, and the surface Wa of the workpiece W. A weld bead Wd is formed on the surface Wa of the workpiece W so as to rise up.

[0030] (Welding current) Figure 4 is a graph showing the change in welding current I over time. The horizontal axis is time t [s]. The vertical axis is welding current I [A]. The welding current I is composed of a pulse wave in which base current IB and peak current IP are periodically repeated alternately. The value of peak current IP is greater than the value of base current IB. In the welding current I, base current IB is the valley and peak current IP is the crest.

[0031] The base current IB may have a predetermined fluctuation range IBa, and the peak current IP may have a predetermined fluctuation range IPa.

[0032] As described above, the average current IA is the average value per period T of the pulsed welding current I. The period T [s] is the reciprocal of the frequency f [Hz] (T=1 / f).

[0033] The average current IA can be kept constant by adjusting the difference between the base current IB and the peak current IP and the frequency f. Specifically, in order to keep the average current IA constant, the peak current IP should be reduced when the base current IB increases, and the peak current IP should be increased when the base current IB decreases. In order to keep the average current IA constant, it may be necessary to adjust the frequency f in some cases.

[0034] (base-peak function) FIG. 5 shows the base-peak function M. As shown in FIG. 5, the horizontal axis, which is one axis of a Cartesian coordinate system, represents the base current IB [A], and the vertical axis, which is the other axis of the Cartesian coordinate system, represents the peak current IP [A]. In the base-peak function M, one of the base current IB and the peak current IP is a function of the other. In the base-peak function M, the base current IB is a function of the peak current IP, and the peak current IP is a function of the base current IB.

[0035] The base-peak function M is a linear function. The base-peak function M is configured as a straight line in a Cartesian coordinate system. A plurality of base-peak functions M are prepared for each average current IA. The plurality of base-peak functions M are stored in the controller of the arc welding device 1.

[0036] The base-peak function M is configured so that the base current IB and the peak current IP have a negative correlation. In the base-peak function M, the peak current IP decreases as the base current IB increases, and the peak current IP increases as the base current IB decreases. In the base-peak function M, the base current IB decreases as the peak current IP increases, and the base current IB increases as the peak current IB decreases.

[0037] The arc welding device 1 (arc welding method) changes the base current IB and peak current IP in accordance with a base-peak function M (along a straight line consisting of the base-peak function M shown in a rectangular coordinate system) while keeping the average current IA constant.

[0038] The base current IB and the peak current IP are changed according to a base-peak function M in accordance with a set value Ua of the penetration depth U into the workpiece W.

[0039] In other words, the base-peak function M is a function that changes the base current IB and the peak current IP according to the set value Ua of the penetration depth U into the workpiece W while keeping the average current IA constant.

[0040] The arc welding device 1 (arc welding method) increases the base current IB and reduces the peak current IP when the set value Ua of the penetration depth U is small (shallow), and reduces the base current IB and increases the peak current IP when the set value Ua of the penetration depth U is large (deep).

[0041] When the base current IB is increased and the peak current IP is decreased, the penetration depth U becomes smaller (shallower), whereas when the base current IB is decreased and the peak current IP is increased, the penetration depth U becomes larger (deeper).

[0042] The set value Ua of the penetration depth U may be represented by an increase or decrease Ub from a reference value Uo of the penetration depth U. In this case, the reference value IBo of the base current IB and the reference value IPo of the peak current IP are set so as to correspond to the reference value Uo of the penetration depth U. The arc welding device 1 (arc welding method) determines the increase or decrease IBb of the base current IB from the reference value IBo and the increase or decrease IPb of the peak current IP from the reference value IPo in accordance with the increase or decrease Ub from the reference value Uo of the penetration depth U.

[0043] The determination of the set value Ua of the penetration depth U, the calculation of the base current IB and the peak current IP using the base-peak function M, and the like are performed by the controller of the arc welding device 1.

[0044] The moving speed V (see FIG. 2) of the welding wire 13 is constant.

[0045] From the viewpoint of suppressing welding defects such as smut and puckering, the arc length L is preferably within ±2 mm with respect to the surface Wa of the workpiece W. From the viewpoint of cost, in order to cope with the rising price of helium, the shielding gas S is preferably composed of 100% argon. From the viewpoint of providing a certain level of heat input to the workpiece W to ensure the penetration depth U, the average current I is preferably 250 A or more. The base current IB is preferably 200 A or more. The peak current IP is preferably 600 A or less.

[0046] Here, smut refers to fine metal oxides that are generated when part of a droplet evaporates from the tip of the welding wire 13 due to arc heat, moves out of the shielded area shielded by the shielding gas S, and then oxidizes and solidifies. Buckling is a phenomenon in which, when the effect of the shielding gas is insufficient, such as when the shielding gas moves out of the shielded area, air (outside air) is drawn in from the periphery of the molten pool, causing a thick, wrinkled oxide film to form on the surface of the weld bead, resulting in the formation of a defective bead that resembles elephant skin.

[0047] (First Example) Table 1 and Fig. 5 show the first example. In the first example, the average current IA was constant at 400 A. In the first example, the welding speed V (the speed at which the welding wire 13 moves in the direction in which the surface Wa of the workpiece W extends (welding direction), see Fig. 2) was constant at 40 cm / min. The plate thickness of the workpiece W was 15 mm. The material of the workpiece W was aluminum. The torch advance angle (when the plate thickness is 12 mm or more and less than 18 mm) was 15°.

[0048] Here, the forward advance angle of the torch is an angle at which the torch is inclined with respect to the vertical direction of the workpiece W so that the torch travels along the weld line and the arc A leads the welding wire 13.

[0049] When the arc length L was within ±2 mm relative to the surface Wa of the workpiece W, it was deemed to have passed, and when the arc length L was greater than +2 mm or less than -2 mm, it was deemed to have failed. When the penetration depth U was 50% or more of the plate thickness (in the first embodiment, 15 mm x 0.5 = 7.5 mm or more), it was deemed to have passed, and when it was otherwise, it was deemed to have failed. The appearance of the bead Wd was evaluated by visually inspecting it. When no welding defects such as smut or puckering were visible in the visual inspection, it was deemed to have passed, and when these welding defects were visible, it was deemed to have failed.

[0050] The horizontal axis, which is one axis of the Cartesian coordinate system, represents the base current IB [A]. The vertical axis, which is the other axis of the Cartesian coordinate system, represents the peak current IP [A]. The welding current I (base current IB and peak current IP) when good results are obtained in the first embodiment belongs to the region between the first line L1 and the second line L2, which represent the relationship between the base current IB and the peak current IP. In this embodiment, the first line L1 and the second line L2 are linear functions. In the first line L1 and the second line L2, one of the base current IB and the peak current IP is a function of the other. In the first line L1 and the second line L2, the base current IB is a function of the peak current IP, and the peak current IP is a function of the base current IB.

[0051] A plurality of first straight lines L1 and a plurality of second straight lines L2 are prepared for each average current IA. The plurality of first straight lines L1 and the plurality of second straight lines L2 are stored in the controller of the arc welding device 1.

[0052] In Table 1 and Fig. 5, I is a missing number. As shown in Table 1 and Fig. 5, good results were obtained in the condition numbers A to G in the first example.

[0053] The conditions under which good results were obtained in the first embodiment are as follows, as shown in Table 1 and FIG. 5. The base current IB is 200 A or more and 400 A or less. The peak current IP is 400 A or more and 600 A or less. The first straight line L1 is IP=-IB+800. The second straight line L2 is IP=-2×IB+1200.

[0054] In the orthogonal coordinate system, the line indicating the base-peak function M is sandwiched between the first line L1 and the second line L2 (passes between the first line L1 and the second line L2).

[0055] In the first embodiment, the base-peak function M is, for example, IP=-1.333×IB+933.33. In this case, when the base current IB is 400A and the peak current IP is 400A, the set value Ua of the penetration depth U is the minimum value, and when the base current IB is 250A and the peak current IP is 600A, the set value Ua of the penetration depth U is the maximum value. For example, the reference value IBo of the base current IB may be set to 325A and the reference value IPo of the peak current IP may be set to 500A so as to correspond to the intermediate value between the minimum value and the maximum value. The set value Ua of the penetration depth U at this time may be set to the reference value Uo.

[0056] [Table 1]

[0057] (Second Example) A second embodiment will now be described. Table 2 and Fig. 6 show the second embodiment.

[0058] Specifically, in the second embodiment, the average current IA is set to a constant value of 300A.

[0059] In the second example, the welding speed V was 40 cm / min. The plate thickness of the workpiece W was 10 mm. The material of the workpiece W was aluminum. The torch advance angle (when the plate thickness was 8 mm or more and less than 12 mm) was 15°. The penetration depth U was deemed to be 50% or more of the plate thickness (in the first example, 10 mm x 0.5 = 5 mm or more) was deemed to be acceptable. The other conditions were the same as those in the first example.

[0060] As shown in Table 2 and FIG. 6, in the second embodiment, good results were obtained under condition numbers A to C.

[0061] The conditions under which good results were obtained in the second embodiment are as follows, as shown in Table 2 and FIG. 6. The base current IB is 220 A or more and 300 A or less. The peak current IP is 300 A or more and 500 A or less. The first straight line L1 is IP = -0.75 x IB + 525. The second straight line L2 is IP = -2.5 x IB + 1050.

[0062] In the orthogonal coordinate system, the straight line represented by the base-peak function M is sandwiched between the first straight line L1 and the second straight line L2 (passes between the first straight line L1 and the second straight line L2).

[0063] In the second embodiment, the base-peak function M is, for example, IP = -1.625 × IB + 787.5. In this case, when the base current IB is 300 A and the peak current IP is 300 A, the set value Ua of the penetration depth U is the minimum value, and when the base current IB is 220 A and the peak current IP is 430 A, the set value Ua of the penetration depth U is the maximum value.

[0064] [Table 2]

[0065] (Third Example) A third embodiment will now be described. Table 3 and Fig. 7 show the third embodiment.

[0066] In the third embodiment, the average current IA is set to a constant value of 500A.

[0067] In the third example, the welding speed V was 40 cm / min. The plate thickness of the workpiece W was 20 mm. The material of the workpiece W was aluminum. The torch advance angle (when the plate thickness was 18 mm or more and less than 25 mm) was 15°. The penetration depth U was deemed to be 50% or more of the plate thickness (in the third example, 20 mm x 0.5 = 10 mm or more) was deemed to be acceptable. The other conditions were the same as those in the first and second examples.

[0068] In Table 3 and Fig. 7, I is a missing number. As shown in Table 3 and Fig. 7, good results were obtained under condition numbers A to D in the third embodiment.

[0069] The conditions under which good results were obtained in the third embodiment are as follows, as shown in Table 3 and FIG. 7. The base current IB is 400 A or more and 500 A or less. The peak current IP is 500 A or more and 600 A or less. The first straight line L1 is IP = -IB + 1000. The second straight line L2 is IP = -5 × IB + 3000.

[0070] In the orthogonal coordinate system, the straight line represented by the base-peak function M is sandwiched between the first straight line L1 and the second straight line L2 (passes between the first straight line L1 and the second straight line L2).

[0071] In the third embodiment, the base-peak function M is, for example, IP = -1.666 × IB + 1333. In this case, when the base current IB is 500 A and the peak current IP is 500 A, the set value Ua of the penetration depth U is the minimum value, and when the base current IB is 440 A and the peak current IP is 600 A, the set value Ua of the penetration depth U is the maximum value.

[0072] [Table 3]

[0073] (flowchart) FIG. 8 shows a flow chart for adjusting the penetration depth U.

[0074] Starting from the start, in a first step S1, an average current (set current) IA is set. For example, the average current IA is set to 400A.

[0075] In a second step S2, the reference value IBo of the base current IB and the reference value IPo of the peak current IP are set so as to correspond to the set average current IA. For example, the reference value IBo of the base current IB is set to 325 A and the reference value IPo of the peak current IP is set to 500 A so as to correspond to the average current IA of 400 A (see FIG. 5).

[0076] In a third step S3, a reference value Uo of the set value Ua of the penetration depth U is set so as to correspond to the set reference value IBo of the base current IB and the reference value IPo of the peak current IP. For example, the reference value Uo of the set value Ua of the penetration depth U is set to 12 mm or the like so as to correspond to a case where the reference value IBo of the base current IB is 325 A and the reference value IPo of the peak current IP is 500 A (when the average current IA is 400 A, the reference value Uo of the set value Ua of the penetration depth U may be set to an appropriate value of 7.5 mm or more).

[0077] In the fourth step S4, it is determined whether or not the set value Ua of the penetration depth U needs to be adjusted. For example, it is determined whether or not the set value Ua of the penetration depth U can remain at the reference value Uo of 12 mm. If it is determined that the adjustment of the set value Ua of the penetration depth U is not necessary (the set value Ua of the penetration depth U can remain at the reference value Uo (12 mm)), the process ends. If it is determined that the adjustment of the set value Ua of the penetration depth U needs to be made (the set value Ua of the penetration depth U cannot remain at the reference value Uo (12 mm)), the process proceeds to the fifth step S5.

[0078] In the fifth step S5, a new set value Ua of the penetration depth U is input. Specifically, since the set value Ua of the penetration depth U is expressed as an increase or decrease value Ub from the reference value Uo, the increase or decrease value Ub of the penetration depth U from the reference value Uo is input. The increase or decrease value Ub is expressed, for example, in millimeters [mm], percentages [%], or dimensionless [-]. In this example, the increase or decrease value Ub is expressed as a unique unit of data number [data]. 1 [data] corresponds, for example, to a number [%] of 1 millimeter [mm]. In other words, 1 [data] is, for example, a ratio corresponding to 1 millimeter [mm]. For example, 1 [data] may be 1 millimeter [mm], or may be a number [%] to several tens [%] of 1 millimeter [mm], or 1 [data] may be a value corresponding to several times 1 millimeter [mm]. The millimeters [mm] and the number of data [data] are in a proportional relationship. In this example, it is assumed that 1 [data] is input as the increase / decrease value Ub.

[0079] In a sixth step S6, an increase or decrease IBb of the base current IB from the reference value IBo and an increase or decrease IPb of the peak current IP from the reference value IPo are set according to the input increase or decrease Ub of the penetration depth U from the reference value Uo.

[0080] For example, when the average current IA is 400 A, the increase or decrease IBb of the base current IB from the reference value IBo is expressed as ±5.0 A / data, and the increase or decrease IPb of the peak current IP from the reference value IPo is expressed as ±6.7 A / data. The larger the increase or decrease Ub of the input penetration depth U, the larger the increase or decrease IBb of the base current IB and the increase or decrease IPb of the peak current IP.

[0081] In a seventh step S7, the value of the base current IB and the value of the peak current IP are changed based on the set increase / decrease values ​​IBb and IPb, and the base current IB and the peak current IP are reset and adjusted.

[0082] In an eighth step S8, welding is performed with the reset and adjusted base current IB and peak current IP.

[0083] In the ninth step S9, it is determined whether or not there is a problem with the penetration depth U in the actually performed welding (Is the penetration depth U OK?). If there is no problem with the penetration depth U, the process proceeds to END. If there is a problem with the penetration depth U, the process returns to the fifth step S5. A problem with the penetration depth U refers, for example, to a case where the penetration depth U in the actually performed welding does not match the set value Ua of the penetration depth U (the increase / decrease value Ub from the reference value Uo). The penetration depth U in the actually performed welding can be detected by a known sensor or visually confirmed (see FIG. 3).

[0084] (Action and effect) According to this embodiment, while keeping the average current IA constant, the base current IB and the peak current IP are changed according to the base-peak function M. This makes it possible to adjust the penetration depth U in arc welding without changing the average current IA.

[0085] Since there is no need to increase or decrease the average current IA in order to change the amount of heat input to the workpiece W, it is easy to handle.

[0086] The base-peak function M is configured so that the base current IB and the peak current IP have a negative correlation. This allows the increase / decrease direction of the base current IB and the increase / decrease direction of the peak current IP to be reversed to each other.

[0087] The base current IB and the peak current IP are changed according to a base-peak function M in response to a set value Ua of the penetration depth U into the workpiece W. This makes it easy to change the base current IB and the peak current IP to obtain a desired penetration depth U.

[0088] When the set value Ua of the penetration depth U is small, the base current IB is increased and the peak current IP is reduced, and when the set value Ua of the penetration depth U is large, the base current IB is reduced and the peak current IP is increased. This makes it easy to adjust the penetration depth U.

[0089] An increase or decrease IBb of the base current IB from the reference value IBo and an increase or decrease IPb of the peak current IP from the reference value IPo are determined according to an increase or decrease Ub of the penetration depth U from the reference value Uo. This makes it easy to adjust the base current IB and the peak current IP.

[0090] The base-peak function M can be simply represented by a straight line in a Cartesian coordinate system.

[0091] The moving speed V of the welding wire 13 is constant. Since there is no need to increase or decrease the moving speed V of the welding wire 13 in order to change the amount of heat input to the workpiece W, handling is easy.

[0092] (Other embodiments) Although the present disclosure has been described above with reference to the preferred embodiments, such description is not limiting, and it goes without saying that various modifications, substitutions, or combinations are possible.

[0093] The base-peak function M is not limited to a straight line, but may be represented, for example, by a curve.

[0094] The arc length L may be greater than +2 mm or less than -2 mm relative to the surface Wa of the workpiece W. The shielding gas S does not need to be composed of 100% argon, and may be mixed with a rare gas such as helium or oxygen, although this increases the cost of the shielding gas S. The average current I may be less than 250 A. The base current IB may be less than 200 A. The peak current IP may be greater than 600 A. [Industrial Applicability]

[0095] The present disclosure is applicable to an arc welding method and an arc welding apparatus, and therefore is extremely useful and has high industrial applicability. [Explanation of symbols]

[0096] 1 Arc welding equipment 13 Welding wire (electrode) A Arc W Work (workpiece) U Penetration Depth Ua setting value Uo Reference Value Ub increase / decrease value V Welding speed I Welding current IA average current IB Base current IBo Reference Value IBb Increase / Decrease IP Peak Current IPo Baseline IPb Increase / Decrease T period M base-peak function L1 1st straight line L2 2nd straight line

Claims

1. An arc welding method for performing welding by supplying a welding current between a workpiece and an electrode to generate an arc, comprising the steps of: The welding current is composed of a pulse wave in which a base current and a peak current are periodically alternately repeated, A method of arc welding comprising: keeping an average current per cycle of the welding current constant; and varying the base current and the peak current according to a base-peak function, one of the base current and the peak current being a function of the other.

2. 2. The arc welding method according to claim 1, wherein the base-peak function is configured such that the base current and the peak current have a negative correlation.

3. 3. The arc welding method according to claim 1, wherein the base current and the peak current are changed according to the base-peak function in response to a set value of a penetration depth into the workpiece.

4. When the set value of the penetration depth is small, the base current is increased and the peak current is reduced; 4. The arc welding method according to claim 3, wherein when the set value of the penetration depth is large, the base current is reduced and the peak current is increased.

5. 5. The arc welding method according to claim 3, wherein the set value of the penetration depth is represented by an increase or decrease value of the penetration depth, and an increase or decrease value of the base current and an increase or decrease value of the peak current are determined according to the increase or decrease value of the penetration depth.

6. Taking the base current on one axis of a Cartesian coordinate system and the peak current on the other axis of the Cartesian coordinate system, 3. The arc welding method according to claim 1, wherein the base-peak function is represented by a straight line in the orthogonal coordinate system.

7. 3. The arc welding method according to claim 1, wherein the electrode is moved at a constant speed.

8. An arc welding device that supplies a welding current between an object to be welded and an electrode to generate an arc and perform welding, The welding current is composed of a pulse wave in which a base current and a peak current are periodically alternately repeated, An arc welding apparatus comprising: an arc welding circuit configured to hold an average current per period of the welding current constant while varying the base current and the peak current according to a base-peak function in which one of the base current and the peak current is a function of the other.

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