WELDING CONTROL METHOD, WELDING CONTROL DEVICE, WELDING POWER SUPPLY, WELDING SYSTEM, PROGRAM, WELDING METHOD, AND ADDITIVE MANUFACTURING METHOD

Abstract

A stable depth of penetration and spatter reduction can be achieved simultaneously in an arc welding method where the forward and reverse feeding of a wire tip are periodically repeated. A total period for the forward feed (TP) and reverse feed (TN) periods is set as one cycle, and a frequency f of one cycle is set as 50 to 150 Hz. A ratio between the average current (IP-AVE) of the non-current suppression period (TIP) and the average current (IB-AVE) of the current suppression period (TIB) is set as 0.65 = IP-AVE / (IP-AVE + IB-AVE) = 0.90. A wave height (Wh), which is the width of variation of the welding wire tip position between the highest and lowest points, is set as 14 to 35% with respect to the distance between the welding wire tip and the base metal.A ratio between any non-current suppression period (TIP) and the current suppression period (TIB) immediately following the non-current suppression period (TIP) is set as 0.30 = TIB / (TIP + TIB) = 0.60, a ratio between the forward feed period (TP) and the reverse feed period (TN) is set as 0.40 = TN / (TP + TN) = 0.70, a ratio between the non-current suppression period (TIP), the current suppression period (TIB), the forward feed period (TP), and the reverse feed period (TN) is set as {TN / (TP + TN)} > {TIB / (TIP + TIB)}, and the non-current suppression period (TIP) is controlled to represent 2 / 3 or more of the forward feed period (TP).

Description

Welding control method, welding control device, welding power source, welding system, program, welding method, and additive manufacturing method

[0001] The present invention relates to a welding control method, a welding control device, a welding power source, a welding system, a program, a welding method, and an additive manufacturing method in an arc welding method in which the feeding of a welding wire is periodically repeated alternately between forward feeding and reverse feeding.

[0002] In welding thick plates, which are primarily used in industries such as steel frames and construction machinery, ensuring a certain penetration depth is required. Furthermore, in welding galvanized steel plates, which are used in industries such as automobiles, preventing porosity is required. Ensuring such penetration depth and preventing porosity can be achieved by increasing the thermal energy of the arc. For this reason, gas-shielded metal arc welding (GMAW) has traditionally been used, incorporating measures such as increasing the arc current density using a shielding gas with a high potential gradient, such as carbon dioxide, or increasing the welding current itself. However, the use of a shielding gas with a high potential gradient or a high welding current increases spatter, resulting in problems such as reduced welding workability due primarily to spatter.

[0003] In response to the above problem, Patent Document 1 addresses the issue of suppressing the generation of spatter even when a large current is passed through a welding wire (hereinafter also referred to as "wire"), which is a consumable electrode, when arc welding is performed by periodically repeating alternating forward and reverse feed of the wire. The patent document discloses that when the tip of the wire is fed toward the base metal while periodically switching between periods of forward feed and periods of reverse feed, by using a control means that changes the welding current in accordance with the periodically fluctuating tip position of the wire, it is possible to reduce spatter even in a high current range where efficient welding with high heat input is possible, i.e., a current range where a transfer mode other than short-circuit transfer occurs.

[0004] Japanese Patent Application Publication No. 2020-49506

[0005] As described above, Patent Document 1 discloses a method for reducing spatter in the high current range, which allows efficient welding with high heat input, but does not specifically mention penetration depth. In other words, Patent Document 1 makes no mention of the effects of ensuring stable penetration depth or preventing porosity defects. Patent Document 1 describes an arc welding method that periodically repeats forward and reverse feed, and, unlike conventional short-circuit transfer methods, controls the welding to prevent short circuits. However, depending on the welding conditions, such as the workpiece conditions and welding position, or disturbances during welding, short circuits may occur during welding control or the timing of droplet detachment may be off, which could prevent stable penetration depth and increase the amount of spatter. Therefore, there is a need for more precise welding control that can achieve both stable penetration depth and spatter reduction regardless of the welding environment.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a welding control method, a welding control device, a welding power source, a welding system, a program, a welding method, and an additive manufacturing method that can achieve both a stable penetration depth and reduced spatter in an arc welding method in which the welding wire is fed alternately and cyclically between forward feed and reverse feed.

[0007] Therefore, the above object of the present invention is achieved by the following configuration [1] relating to a welding control method.

[0008] [1] In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢA welding control method for controlling a welding operation by switching the normal feed period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ A welding control method characterized by controlling the welding so that

[0009] The above object of the present invention can be achieved by the following configuration [2] relating to a welding control device.

[0010] [2] In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ A welding control device for switching and controlling the normal feed period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is as follows: 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +TＮ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ A welding control device characterized by having a function of controlling so that

[0011] The above object of the present invention is also achieved by the following configuration [3] relating to a welding power source.

[0012] [3] A welding power source comprising the welding control device according to [2].

[0013] The above object of the present invention is also achieved by the following configuration [4] relating to a welding system.

[0014] [4] A welding system comprising the welding control device according to [2] or the welding power source according to [3].

[0015] The above object of the present invention can be achieved by the following configuration [5] relating to a program.

[0016] [5] In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ a welding control device for controlling the welding system by switching between the normal feed period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period TＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ A program characterized by executing a function to control the occupancy of

[0017] The above object of the present invention is also achieved by the following configuration [6] relating to a welding method.

[0018] [6] In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎand controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ A welding method for performing gas metal arc welding while performing welding control by switching between the normal feed period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰThe welding method is characterized in that the welding control is performed so that the welding time is

[0019] The above object of the present invention is also achieved by the following configuration [7] relating to an additive manufacturing method.

[0020] [7] In additive manufacturing using gas metal arc welding, in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ An additive manufacturing method for performing additive manufacturing while performing welding control by switching to and controlling the normal feeding period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ)≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ An additive manufacturing method characterized in that the welding control is performed so that

[0021] The welding control method, welding control device, welding power source, welding system, program, welding method, and additive manufacturing method of the present invention make it possible to achieve both stable penetration depth and reduced spatter in an arc welding method in which the welding wire is fed alternately and cyclically between forward and reverse feed.

[0022] Fig. 1 is a schematic diagram showing an example of the configuration of a welding system according to this embodiment. Fig. 2 is a block diagram showing the schematic configuration of a power supply control unit in a welding power supply. Fig. 3 is a block diagram showing the configuration of a welding system according to this embodiment. Ｗ FIG. 4 is a waveform diagram illustrating the time change of the tip position of the welding wire. FIG. 5 is a flowchart illustrating an example of basic control of the welding current in this embodiment. FIG. 6 is a diagram illustrating an example of control of the current setting signal Ir that specifies the current value of the welding current. FIG. 7 is a series of photographs taken by a high-speed camera showing an example of the progress of welding in a conventional short-circuit transfer method, and are photographs substituted for drawings at each elapsed time for Test No. 24, which is a reference example described below. FIG. 8 is a series of photographs taken by a high-speed camera showing an example of the progress of welding in this embodiment, and are photographs substituted for drawings at each elapsed time for Test No. 8, which is an example described below. FIG. 9A is a waveform diagram illustrating the time change of the welding current setting value Ir. Ｐ１ End position and welding current setting value I Ｐ２ The wire feed speed F Ｗ 9B is a diagram showing the relationship between the wire tip position and the welding current setting value during the current suppression period TＩＢ The wire feed speed F Ｗ 10 is a diagram showing the relationship between the number of short circuits and the penetration depth, and FIG.

[0023] Hereinafter, embodiments of a welding control method, a welding control device, a welding power source, a welding system, a program, a welding method, and an additive manufacturing method according to the present invention will be described in detail with reference to the drawings.

[0024] Note that this embodiment is an example of a case where a welding robot is used, and the welding control method according to the present invention is not limited to the configuration of this embodiment. For example, the welding control method according to the present invention may be applied to an automatic welding device using a cart, or to a small, portable welding robot. Also, this embodiment uses a gas metal arc welding method using a pulse waveform. Furthermore, this embodiment describes a gas metal arc welding method to which the welding control method according to the present invention is applied, but the welding control method according to the present invention can also be applied to an additive manufacturing method that uses gas metal arc welding.

[0025] Furthermore, the method for measuring welding behavior according to the present invention is useful not only for welding but also for additive manufacturing technology using GMAW, specifically for metal additive manufacturing (WAAM: Wire and Arc Additive Manufacturing). The term "additive manufacturing" is sometimes used broadly to refer to additive manufacturing or rapid prototyping, but in the present invention, the term "additive manufacturing" is used consistently. When the method according to the present invention is used for additive manufacturing technology, "welding" can be replaced with "deposition," "additive manufacturing," "additive manufacturing," or the like. For example, when treated as welding, it is called "welding behavior," but when the present invention is used as additive manufacturing, it can be replaced with "deposition behavior," or when treated as welding, it is called a "welding system," but when the present invention is used as additive manufacturing, it can be replaced with "additive manufacturing system."

[0026] 1 is a schematic diagram showing an example of the configuration of a welding system according to this embodiment. The welding system 50 includes a welding robot 110, a welding control device 120, a welding wire feeder (not shown) that feeds welding wire 100, a welding power source 140, and a controller 150.

[0027] Welding power source 140 is connected to welding robot 110 via a positive power cable (not shown) so as to be able to energize welding wire 100, which is a consumable electrode, and is connected to workpiece (hereinafter also referred to as "base material") 200 via a negative power cable (not shown). This connection is for the case where welding is performed with reverse polarity; when welding with positive polarity is performed, the polarity of welding power source 140 can be reversed.

[0028] Furthermore, welding power source 140 and a feeder for feeding welding wire 100 are connected by a signal line, so that the feed speed of the welding wire can be controlled.

[0029] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a current-carrying mechanism, i.e., a welding tip, that applies current to the welding wire 100. When current is applied from the welding tip, the welding wire 100 generates an arc from its tip, and the generated heat welds the workpiece 200, which is the welding target. The welding tip is also generally referred to as a contact tip.

[0030] Furthermore, the welding torch 111 includes a shielding gas nozzle, which serves as a mechanism for ejecting the shielding gas. Due to the characteristics of the control used in this embodiment, the shielding gas may have a gas composition that exhibits globular transition. Specifically, it is preferable that the shielding gas contains at least one gas with a high potential gradient: carbon dioxide, nitrogen, hydrogen, or oxygen. From the viewpoint of versatility, carbon dioxide gas alone is more preferable. In the case of a mixed gas with argon gas (hereinafter also referred to as "Ar gas"), it is more preferable that the mixed gas contains at least one gas from carbon dioxide, nitrogen, hydrogen, or oxygen, with a total of 5 to 50 volume % of gases other than Ar gas. The shielding gas is supplied from a shielding gas supply device (not shown).

[0031] The welding wire 100 used in this embodiment is not particularly limited; for example, either a solid wire containing no flux or a flux-cored wire containing flux may be used. The material of the welding wire 100 is also not limited; for example, the material may be mild steel, stainless steel, aluminum, or titanium, and the wire surface may be plated with Cu or the like. Furthermore, the diameter of the welding wire 100 is also not particularly limited. In this embodiment, the upper limit of the diameter is preferably 1.6 mm, and the lower limit is preferably 0.8 mm.

[0032] Furthermore, in this embodiment, the specific configuration of the workpiece 200 is not particularly important, and the working conditions such as the joint shape, welding position, and groove shape are also not particularly important.

[0033] Welding control device 120 mainly controls the operation of welding robot 110. Welding control device 120 holds teaching data that predefines the operation pattern, welding start position, welding end position, welding conditions, weaving operation, etc. of welding robot 110, and controls the operation of welding robot 110 by instructing welding robot 110 on these data. Welding control device 120 also provides welding conditions, such as welding current, welding voltage, and feed speed, to welding power source 140 during welding operations in accordance with the teaching data. As shown in FIG. 1 , welding system 50 of this embodiment has welding control device 120 configured independent of welding power source 140, but welding control device 120 may also be configured to be included within welding power source 140.

[0034] Controller 150 is connected to welding control device 120, and creates or displays programs for operating welding robot 110, inputs teaching data, and provides the programs to welding control device 120. Controller 150 also has a function for manually operating welding robot 110. The connection between controller 150 and welding control device 120 can be wired or wireless.

[0035] In response to a command from welding control device 120, welding power source 140 supplies power to welding wire 100 and workpiece 200, thereby generating an arc between welding wire 100 and workpiece 200. In response to a command from welding control device 120, welding power source 140 also outputs a signal to a feeder (not shown) to control the speed at which welding wire 100 is fed.

[0036] <Functional Configuration of Welding Power Source> Next, the functional configuration of the welding power source 140 according to this embodiment will be described in detail with reference to FIG. 2. FIG. 2 is a block diagram showing a schematic configuration of a power source control unit in the welding power source 140. The control system portion of the welding power source 140 is executed, for example, by the welding control device 120 or a computer (not shown) executing a program. The control system portion of the welding power source 140 includes a current setting unit 36. In this embodiment, the current setting unit 36 ​​has a function of setting various current values ​​that define the welding current flowing through the welding wire 100, a function of setting the start and end times of a period during which the current value of the welding current is suppressed by a current suppression period setting unit 36A, and a function of obtaining information on the tip position of the welding wire 100 by a wire tip position conversion unit 36B. Note that the current non-suppression period T ＩＰ Various condition settings, for example, the rising section T Ｕ and falling section T Ｄ The current setting point and the like are included in the function of setting various current values ​​that define the welding current in the current setting unit 36.

[0037] In this embodiment, the welding current is ＩＰ and the current suppression period T ＩＢ The current setting unit 36 ​​alternately sets the welding current in a pulse waveform T ＩＰ The set current value Ip (hereinafter also referred to as "peak current Ip") and the current suppression period T ＩＢA set current value Ib (hereinafter also referred to as "base current Ib") is set. Note that a steady current Ia for reset control of droplet detachment timing, which will be described later, may also be set. In this embodiment, the welding current is basically controlled by two values, the peak current Ip and the base current Ib. Therefore, the time t1 at which the period in which the current value is suppressed starts represents the time at which the base current Ib starts, i.e., the base current start time. The time t2 at which the period in which the current value is suppressed ends represents the time at which the base current Ib ends, i.e., the base current end time. Note that the current non-suppression period T ＩＰ The time when the peak current starts is called the peak current start time, and the current non-suppression period T ＩＰ The time at which the peak current ends may be referred to as the peak current end time.

[0038] The main power supply circuit of the welding power supply 140 is composed of a three-phase AC power supply (hereinafter also referred to as the “AC power supply”) 1, a primary side rectifier 2, a smoothing capacitor 3, a switching element 4, a transformer 5, a secondary side rectifier 6, and a reactor 7.

[0039] AC power input from AC power supply 1 is full-wave rectified by primary-side rectifier 2 and further smoothed by smoothing capacitor 3 to be converted into DC power. Next, the DC power is converted into high-frequency AC power by inverter control using switching element 4, and then converted into secondary-side power via transformer 5. The AC output of transformer 5 is full-wave rectified by secondary-side rectifier 6 and further smoothed by reactor 7. The output current of reactor 7 is provided to welding tip 8 as an output from the main power supply circuit, and is passed through welding wire 100, which serves as a consumable electrode.

[0040] The welding wire 100 is fed by the feed motor 24 and the feed device 130, and an arc 9 is generated between the welding wire 100 and the base material 200. In this embodiment, the feed motor 24 moves the tip of the welding wire 100 toward the base material 200 during a forward feed period T Ｐ and a reverse feed period T during which the tip of the welding wire 100 moves in a direction opposite to the direction in which the base material 200 is located. ＮThe welding wire 100 is fed so that the wire feed speed and the wire melting speed are periodically switched. Note that the "tip of the welding wire" here generally refers to the wire tip when ignoring the presence of droplets hanging from the wire tip. In other words, the wire melted by the arc is considered to have immediately transferred to the base metal. As will be described later, the position is determined by the speed difference between the wire feed speed and the wire melting speed.

[0041] The feeding of the welding wire 100 by the feed motor 24 is controlled by a control signal Fc from the feed drive unit 23. The average value of the feed speed is approximately the same as the melting speed. In this embodiment, the feeding of the welding wire 100 by the feed motor 24 is also controlled by the welding power source 140.

[0042] The current setting unit 36 ​​receives a voltage setting signal Vr from the voltage setting unit 34, which is a target value for the voltage to be applied between the welding tip 8 and the base material 200. The voltage setting signal Vr is also provided to the voltage comparison unit 35, which compares it with the voltage detection signal Vo detected by the voltage detection unit 32. The voltage detection signal Vo is an actual measurement value. The voltage comparison unit 35 amplifies the difference between the voltage setting signal Vr and the voltage detection signal Vo, and outputs the amplified voltage error signal Va to the current setting unit 36. The current setting unit 36 ​​controls the welding current so that the length of the arc 9 (hereinafter also referred to as "arc length") remains constant. That is, the current setting unit 36 ​​performs constant voltage control by controlling the welding current.

[0043] The current setting unit 36 ​​resets the value of the peak current Ip, the value of the base current Ib, the period for providing the peak current Ip, or the magnitude of the value of the peak current Ip and the value of the base current Ib based on the voltage setting signal Vr and the voltage error amplification signal Va, and outputs a current setting signal Ir to the current error amplification unit 37 according to the reset period or the magnitude of the reset value.

[0044] The current error amplifier 37 amplifies the difference between the current setting signal Ir given as a target value and the current detection signal Io detected by the current detector 31, and outputs the amplified current error signal Ed to the inverter driver 30. The inverter driver 30 corrects the drive signal Ec of the switching element 4 using the amplified current error signal Ed.

[0045] A detachment detection signal Drl, which is a signal for detecting detachment of a droplet from the tip of the welding wire 100, is also input to the current setting unit 36. The detachment detection signal Drl is output from the detachment detection unit 33. The detachment detection unit 33 monitors a change in the voltage detection signal Vo output by the voltage detection unit 32, and detects detachment of a droplet from the welding wire 100 from the change. The detachment detection unit 33 is an example of a detection means.

[0046] The detachment detection unit 33 detects droplet detachment by, for example, comparing a value obtained by differentiating or second-order differentiating the voltage detection signal Vo with a detection threshold value. The detection threshold value is pre-stored in a storage unit (not shown). The detachment detection unit 33 may generate the detachment detection signal Drl based on a change in resistance value calculated from the voltage detection signal Vo and the current detection signal Io, which are actual measured values.

[0047] The current setting unit 36 ​​is also provided with an average feed speed Fave of the welding wire 100 being fed. The average feed speed Fave is output by the average feed speed setting unit 20 based on teaching data stored in a storage unit (not shown). In other words, the average feed speed Fave may be referred to as a feed speed setting value (command value). Based on the provided average feed speed Fave, the current setting unit 36 ​​determines values ​​of the peak current Ip, the base current Ib, the time t1 when the base current Ib starts, and the time t2 when the base current Ib ends.

[0048] 2, the average feed rate Fave is input to the current setting unit 36. However, a value related to the average feed rate Fave may be used as a set value in place of the average feed rate Fave in the signal input to the current setting unit 36. For example, if a database of average feed rates Fave and average current values ​​that enable optimal welding for the average feed rate Fave is stored in a storage unit (not shown), the average current value may be used as a set value in place of the average feed rate Fave.

[0049] The average feed speed Fave is also provided to the amplitude feed speed setting unit 21 and the feed speed command setting unit 22. The amplitude feed speed setting unit 21 determines the amplitude Wf ​​and period Tf based on the input average feed speed Fave. Amplitude feed refers to a feeding method in which a forward feed period, during which the feed speed is higher than the average feed speed Fave, and a reverse feed period, during which the feed speed is lower than the average feed speed Fave, alternate. The period during which the feed speed is lower than the average feed speed Fave refers to a period less than the average feed speed Fave, including a negative feed speed, i.e., a speed at which the wire tip moves in the opposite direction from the position of the base material 200. The amplitude Wf ​​determines the variation width of the average feed speed Fave, and the period Tf determines the time of amplitude change, which is the repetition unit. The amplitude feed speed setting unit 21 generates and outputs an amplitude feed speed Ff according to the determined amplitude Wf ​​and period Tf or frequency f.

[0050] The feed speed command setting unit 22 outputs a feed speed command signal Fw based on the amplitude feed speed Ff and the average feed speed Fave. In this embodiment, the feed speed command signal Fw is expressed by the following equation: Fw=Ff+Fave (1)

[0051] However, the feed speed command signal Fw expressed by Equation (1) is valid only when detachment of a droplet from the tip of the welding wire 100 is detected within an expected period. If detachment of a droplet is not detected within the expected period, the feed speed command setting unit 22 may switch the feed speed command signal Fw to feed control at a constant speed. For example, the feed speed command setting unit 22 switches the feed speed command signal Fw to feeding at an average feed speed Fave. The switch from feeding at the average feed speed Fave to the feed control expressed by Equation (1) is determined depending on the timing at which detachment of a droplet is detected. A specific control example will be described later. The feed speed command setting unit 22 detects at which phase of the amplitude feed detachment occurred based on the detachment detection signal Drl provided by the detachment detection unit 33.

[0052] The feed speed command signal Fw is output to the phase shift detection unit 26, the feed error amplification unit 28, and the current setting unit 36. The feed error amplification unit 28 amplifies the difference between the feed speed command signal Fw, which is a target speed, and the feed speed detection signal Fo, which is an actual measurement of the feed speed of the welding wire 100 by the feed motor 24, and outputs a speed error amplified signal Fd, in which the error is corrected, to the feed drive unit 23. The feed drive unit 23 generates a control signal Fc based on the speed error amplified signal Fd and provides it to the feed motor 24. The feed speed conversion unit 25 here converts the rotation amount of the feed motor 24, etc., into the feed speed detection signal Fo of the welding wire 100. The phase shift detection unit 26 in this embodiment compares the feed speed command signal Fw with the feed speed detection signal Fo, which is a measured value, and outputs a phase shift time Tθd. In addition, the phase shift detection unit 26 may measure the feeding operation of the feed motor 24 when parameters that define the amplitude feeding, such as the period Tf, amplitude Wf, and average feeding speed Fave, are varied, and determine the phase shift time Tθd.

[0053] The phase shift time Tθd is provided to a wire tip position conversion unit 36B of the current setting unit 36. The wire tip position conversion unit 36B calculates the tip position of the welding wire 100 with respect to the base material 200 as a reference plane based on the feed speed command signal Fw and the phase shift time Tθd, and provides information on the calculated tip position to the current suppression period setting unit 36A. Here, the current suppression period setting unit 36A sets a period during which the welding current is suppressed, i.e., a period during which the current setting signal Ir is controlled to the base current Ib, based on information on the tip position of the welding wire 100 or based on information on the tip position of the welding wire 100 and the feed speed command signal Fw. The current setting unit 36 ​​here is an example of a control means that changes the welding current in accordance with the tip position of the welding wire 100.

[0054] <Basic Control of Welding Current Based on Information on Tip Position of Welding Wire or Feed Speed ​​Command Signal Fw> An example of control of the welding current by the welding power source 140 based on information on the tip position of the welding wire 100 or the feed speed command signal Fw will be described below. The control of the welding current is achieved by the current setting unit 36 ​​that constitutes the welding power source 140. As described above, the current setting unit 36 ​​in this embodiment achieves control through the execution of a program.

[0055] The current setting unit 36 ​​in this embodiment controls switching of the current value of the welding current based on information on the tip position of the welding wire 100 and a feed speed command signal Fw for the welding wire 100. Therefore, prior to describing the control of the welding current, the time change of the feed speed command signal Fw and the time change of the tip position of the welding wire 100 will be described.

[0056] FIG. 3 is a waveform diagram illustrating the change over time of the feed speed command signal Fw. The horizontal axis represents time (phase), and the vertical axis represents the wire feed speed. The units of the vertical axis are meters per minute or revolutions. In FIG. 3, a speed higher than the average feed speed Fave is represented as "forward feed," and a speed lower than the average feed speed Fave is represented as "reverse feed." In this embodiment, the feed speed command signal Fw changes in a sinusoidal shape defined by a period Tf and an amplitude Wf. Hereinafter, the period during which the feed speed is higher than the average feed speed Fave is referred to as the forward feed period T Ｐ Conversely, the period during which the feeding speed is slower than the average feeding speed Fave is called the reverse feeding period T Ｎ For convenience of explanation, the first half of each feeding period will be referred to as the "first half" and the second half as the "second half." Here, the average feeding speed Fave can be regarded as the wire melting speed Fm. In the following, as shown in FIG. 3, the normal feeding period T Ｐ and the reverse feeding period T Ｎ The amplitude feed that is periodically repeated is sometimes called the "initial condition."

[0057] 4 is a waveform diagram illustrating a change over time in the tip position of the welding wire 100 (hereinafter also referred to as the "wire tip position"). The horizontal axis represents time (phase), and the vertical axis represents the distance (height) upward in the normal direction from the surface of the base material 200. In FIG. 4, the position (height) when the welding wire 100 is fed at the maximum or minimum feed rate is defined as a reference distance, and distances greater than the reference distance are represented by positive values, and distances smaller than the reference distance are represented by negative values.

[0058] 4, the time points corresponding to the position where the tip of the welding wire 100 is closest to the base metal surface (hereinafter also referred to as the "lowest end") are represented by T0 and T4, and the time point corresponding to the position where the tip of the welding wire 100 is farthest from the base metal surface (hereinafter also referred to as the "uppermost end") is represented by T2. The apex here is an example of the uppermost end.

[0059] As shown in FIG. 4 , the period during which the tip position of the welding wire 100 approaches the base metal surface over time, specifically, the period during which the tip position of the welding wire 100 moves from the uppermost end to the lowermost end, is called the “normal feeding period T Ｐ ", and the period during which the tip position of the welding wire 100 moves away from the surface of the base material with the passage of time, specifically, the period during which the tip position of the welding wire 100 moves from the lowest end to the highest end, is the "reverse feeding period T Ｎ "

[0060] Also, time points corresponding to the reference distance are designated as T1 and T3. T1 is an intermediate time point from the bottom end, where the tip position of the welding wire 100 is closest to the base metal surface, to the top end, where the tip position is farthest from the base metal surface. On the other hand, T3 is an intermediate time point from the top end to the bottom end. As shown in Fig. 4 , the change width from the reference distance to the top end or the change width from the reference distance to the bottom end is the "amplitude Wf," and the change width from the top end to the bottom end is the "wave height Wh."

[0061] 3 and 4 , the feed speed of the welding wire 100 when the tip of the welding wire 100 is located at the uppermost or lowermost end is set to a predetermined average feed speed Fave. This allows the wire melting rate and the wire feed speed to be balanced even if the wire feed speed changes periodically, and the arc length becomes approximately constant, allowing stable welding to be continued.

[0062] FIG. 5 is a flowchart illustrating an example of basic control of the welding current in this embodiment. The control shown in FIG. 5 is executed by the current setting unit 36 ​​described in FIG. 2. The symbol S in the figure indicates a step. The control shown in FIG. 5 corresponds to one cycle of change in the tip position of the welding wire 100. Therefore, in FIG. 5, the state at time T=time T0 is designated as step 1. In this embodiment, the current setting unit 36 ​​calculates the tip position of the welding wire 100 to control the current setting signal Ir. The average feed speed Fave is equivalent to the wire melting speed Fm. Therefore, the tip position of the welding wire 100 can be determined by integrating the difference between the feed speed command signal Fw and the wire melting speed Fm (≈Fave). Therefore, the current setting unit 36 ​​sets the tip position of the welding wire 100 based on the following equation: Wire tip position = ∫(Fw - Fave) dt Equation (2) The change in tip position calculated by Equation (2) corresponds to FIG. 4.

[0063] However, when the feed motor 24 described in FIG. 2 is used to feed the welding wire 100, a phase shift may occur between the command and the actual feed speed, i.e., the feed speed detection signal Fo. Therefore, the current setting unit 36 ​​corrects the base current start time t1, which is calculated according to the tip position of the welding wire 100 calculated from the average feed speed Fave and the feed speed command signal Fw, using the phase shift time Tθd provided by the phase shift detection unit 26. Specifically, the value of the base current start time t1 is reset as shown in the following equation: t1=t1+Tθd (3)

[0064] Similarly, the current setting unit 36 ​​corrects the base current end time t2 calculated from the average feed speed Fave and the feed speed command signal Fw using the phase shift time Tθd: t2=t2+Tθd (4) Here, the case where the base current start time t1 and the base current end time t2 are controlled from the viewpoint of the feed speed has been described, but the same applies from the viewpoint of position control.

[0065] 6 is a diagram showing an example of control of the current setting signal Ir that specifies the current value of the welding current. The horizontal axis represents time, and the vertical axis represents the current detection signal Io. Times T0, T1, T2, T3, and T4 in the diagram correspond to times T0, T1, T2, T3, and T4 in FIG. 4, respectively. The times T0, T1, T2, T3, and T4 here are determined from the tip position of the welding wire 100, which is calculated from the average feed speed Fave and the feed speed command signal Fw.

[0066] As shown in FIG. 6, the base current start time t1 is the time T0 when the tip of the welding wire 100 is at the lowest position, that is, the time T Ｐ From the reverse feeding period T Ｎ 6, the maximum value of the base current start time t1 is represented as t1'.

[0067] Returning now to the description of Fig. 5 , as shown in step 2, when the tip position of the welding wire 100 reaches the lowest end, i.e., time T0, the current setting unit 36 ​​determines whether the time T, which is the time when measurement started from time T0, is equal to or longer than the base current start time t1. While the determination result of step 2 is negative (false), as shown in step 3, the current setting unit 36 ​​continues to output the peak current Ip as the current setting signal Ir. This period corresponds to the current non-suppression period T in Fig. 6 . ＩＰ Corresponds to.

[0068] 5, when the determination result in step 2 becomes affirmative (True), the current setting unit 36 ​​starts outputting the base current Ib as the current setting signal Ir as shown in step 4. As described above, when the switching to the base current Ib starts, the feeding of the welding wire 100 has already ended in the reverse feeding period T Ｎ , and the tip of the welding wire 100 begins to move in a direction away from the surface of the base material.

[0069] The molten metal droplet near time T0, when the tip of the welding wire 100 is at the lowest position, is located near the molten pool, and therefore the arc length is short. ＮThat is, the tip of the welding wire 100 moves in a manner such that it is pulled up. An inertial force acts on the entire grown droplet in the forward feeding direction, i.e., in the direction toward the base material 200, while the welding wire 100 moves in the opposite direction, i.e., in the direction away from the base material 200, so that the droplet changes to a more pendant shape, further facilitating detachment.

[0070] Furthermore, by switching the welding current value to the base current Ib during the period when separation is predicted, the arc reaction force can be reduced compared to the period when the peak current Ip is supplied. As a result, the force lifting the droplet becomes even weaker, making it even more likely for the droplet to become suspended. In this way, during the current suppression period T, during which the welding current is suppressed, ＩＢ In addition, by detaching the droplets from the tip of the welding wire 100, it is expected that spatter will be reduced.

[0071] Returning to the explanation of FIG. 5 , as shown in step 5, the current setting unit 36, which has switched the current setting signal Ir to the base current Ib, determines whether the time T is equal to or longer than the base current end time t2. In FIG. 6 , the maximum value of the base current end time t2 is indicated by t2′. While the determination result in step 5 is negative (False), as shown in step 4, the current setting unit 36 ​​outputs the base current Ib as the current setting signal Ir. After the supply of the base current Ib is started, the tip of the welding wire 100 moves so as to be pulled up to the apex, i.e., the position where the tip is farthest from the base material 200, accompanied by the detachment of a droplet.

[0072] After the droplet is separated, a period during which the base current Ib is supplied, i.e., a current suppression period T ＩＢ and the period during which the peak current Ip is supplied, i.e., the current non-suppression period T ＩＰ Therefore, it is desirable that the supply of the base current Ib be terminated between times T1 and T2.

[0073] If the determination result in step 5 is positive (True), the current setting unit 36 ​​starts outputting the peak current Ip as the current setting signal Ir, as shown in step 6. Subsequently, as shown in step 7, the current setting unit 36 ​​determines whether the time T, from which measurement started from time T0, has reached time T4. While the determination result in step 7 is negative (False), the current setting unit 36 ​​outputs the peak current Ip as the current setting signal Ir, as shown in step 6. On the other hand, if the determination result in step 7 is positive (True), the current setting unit 36 ​​returns to step 1. Through the above control, the current setting signal Ir becomes a pulse waveform that periodically repeats the peak current Ip and the base current Ib.

[0074] <Method of controlling droplet detachment> The above explanation is the basic control of the welding current by the welding power source 140 based on the information on the tip position of the welding wire 100 or the feed speed command signal Fw. In actual welding, there is a possibility that detachment will not occur as expected depending on the welding environment, such as the construction situation or disturbance. In this embodiment, the value of the frequency f, the peak current Ip, i.e., the current non-suppression period T ＩＰ The set current, the base current Ib, that is, the current suppression period T ＩＢ The set current, the current non-suppression period T ＩＰ (which may also be referred to as the "peak current period"), the current suppression period T ＩＢ (which may also be referred to as the "base current period"), the positive feed period T Ｐ , reverse feeding period T Ｎ By controlling each of the above under the conditions described in detail below, droplet separation can be controlled with higher accuracy.

[0075] In addition, the current non-suppression period T ＩＰ The set current or current suppression period T ＩＢ The set current is not limited to a constant current value, and the set value may be changed within each period. ＩＰ Overall or current suppression period T ＩＢ As an index showing the total heat energy, the current non-suppression period T ＩＰ or current suppression period T ＩＢ The average current is expressed as the current non-suppression period T ＩＰ The average current ofＰ－ＡＶＥ " and the current suppression period T ＩＢ The average current of Ｂ－ＡＶＥ " is displayed.

[0076] Each control element will be described in detail below.

[0077] (Frequency f: 50 to 150Hz) Normal feeding period T Ｐ and the reverse feeding period T Ｎ The combined period of these is considered one cycle, and the frequency f is controlled to suppress short circuits by stably detaching or dripping droplets formed at the tip of the welding wire. This frequency f is set in the range of 50 to 150 Hz, which satisfies the conditions described below, i.e., the condition for forming optimal droplet size while maintaining penetration depth. If the frequency f is below 50 Hz, excessively large droplets will form at the wire tip, but the inertial force acting on the droplets will be insufficient, making the large droplets more likely to come into contact with the molten pool and less likely to detach. As a result, short circuits will increase, which in turn increases spatter and makes it difficult to achieve a stable penetration depth.

[0078] On the other hand, when the frequency f exceeds 150 Hz, the size of the droplet formed at the wire tip does not grow to the optimum size, and the inertial force is insufficient, so the current suppression period T ＩＢ Therefore, stable detachment cannot be achieved at this temperature. As a result, droplets may detach at unintended times, causing short circuits and spattering. Therefore, the frequency f is set to a range of 50 to 150 Hz, preferably 60 to 130 Hz, and more preferably 70 to 120 Hz.

[0079] The droplet size suitable for the aforementioned frequency f is 1.7 to 5.0 mm in average volume. ３ The droplet size here means the size of the droplet just before it separates, and examples of the method include a method of calculating the volume from the melting speed Fm, and a method of taking images from one or more directions with a visual sensor and calculating the volume based on the obtained two-dimensional images. ３Within this range, it is possible to more effectively suppress short circuits, reduce spatters, and effectively obtain a stable penetration depth.

[0080] (0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90) Current non-suppression period T ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ I for the sum of Ｐ－ＡＶＥ The ratio of I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ ) is in the range of 0.65 to 0.90. If the above ratio falls below 0.65, the current non-suppression period T ＩＰ In this period, the electromagnetic pinch force acting on the droplet becomes smaller, and the current suppression period T ＩＢ In this case, droplet detachment becomes difficult due to inertial force alone, and the timing of detachment is shifted, making it more likely that a short circuit will occur. This short circuit will then cause spattering, making it impossible to obtain a stable penetration depth. ＩＰ In this case, the thermal energy tends to be small, and therefore the penetration depth in particular becomes shallow.

[0081] On the other hand, when the ratio exceeds 0.90, the current non-suppression period T ＩＰ In this process, as the droplet size becomes excessively large, the arc pressure applied to the droplet (hereinafter, also referred to as "arc reaction force" when referring to the arc pressure on the droplet) becomes excessive, causing the pushed-up droplet to detach in a direction different from the molten pool, which makes it easy for large spatter to occur. In addition, arc interruption and long-term short circuits are also likely to occur, which causes spatter to occur and makes it impossible to obtain a stable penetration depth. Therefore, I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ ) is defined to be in the range of 0.65 to 0.90, preferably 0.70 to 0.85.

[0082] (Wave height Wh: 14 to 35% of tip-base metal distance) As shown in Figure 4, the wave height Wh, which is the range of change in the tip position of the welding wire 100 between the uppermost end and the lowermost end, is set to a range of 14 to 35% of the tip-base metal distance. For example, when the tip-base metal distance is 25 mm, the range of the wave height Wh that should be set is 3.75 mm to 8.75 mm. If the wave height Wh is outside the range of 14 to 35% of the tip-base metal distance, short circuits cannot be prevented. The "reference distance" that serves as the reference position for the wave height Wh and amplitude Wf ​​may be set arbitrarily.

[0083] (0.30≦T ＩＢ / (T ＩＰ +T ＩＢ ) ≦0.60) Any current non-suppression period T ＩＰ and the current suppression period T immediately thereafter ＩＢ The current suppression period T ＩＢ The ratio of T ＩＢ / (T ＩＰ +T ＩＢ ) is in the range of 0.30 to 0.60. When the above ratio falls below 0.30, the current suppression period T ＩＢ In this period, the droplet formed at the tip of the wire does not completely separate, and the current is not suppressed during the period T ＩＰ The arc reaction force causes the weld to easily separate, which increases short circuits and spatter, making it difficult to obtain a stable penetration depth.

[0084] On the other hand, if the ratio exceeds 0.60, the electromagnetic pinch force is insufficient, and the current suppression period T ＩＢ Therefore, droplets may be detached at unintended times, causing short circuits and spatters. ＩＢ / (T ＩＰ +T ＩＢ ) is specified to be in the range of 0.30 to 0.60, preferably 0.31 to 0.58, and more preferably 0.31 to 0.52.

[0085] (0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70) Positive feeding period T Ｐ and the reverse feeding period TＮ The reverse feeding period T Ｎ The ratio of T Ｎ / (T Ｐ +T Ｎ If the ratio is less than 0.40, it is not possible to obtain sufficient time for droplet detachment, and the current suppression period T ＩＢ As a result, droplets can detach at unintended times, causing short circuits and spattering.

[0086] On the other hand, when the ratio exceeds 0.70, the droplet formed at the wire tip is elongated and thin, and the reverse feed period T Ｎ Short circuits are likely to occur before T Ｎ / (T Ｐ +T Ｎ ) is defined in the range of 0.40 to 0.70.

[0087] {T Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )} Normal feeding period T ｐ and the reverse feeding period T Ｎ The reverse feeding period T Ｎ The ratio of T Ｎ / (T Ｐ +T Ｎ )} and the current non-suppression period T ＩＰ and the current suppression period T ＩＢ The current suppression period T ＩＢ The ratio of T ＩＢ / (T ＩＰ +T ＩＢ )} is expressed as follows: Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}. Ｎ / (T Ｐ +T Ｎ )} is {T ＩＢ / (T ＩＰ +T ＩＢ)) below, the arc force at the timing when the tip of the wire approaches the molten pool before reverse feeding occurs becomes insufficient, resulting in shallow penetration depth.

[0088] That is, if there is sufficient arc pressure before and after the wire tip is at the lowest end, even if the average arc length is short, a buried arc state without short circuit can be achieved and sufficient penetration depth can be obtained. However, as described above, the timing before and after the wire tip is at the lowest end is shorted due to the current suppression period T ＩＢ If the welding current is too high, sufficient arc pressure cannot be obtained, which makes it easier for the droplets to come into contact with the molten pool and short-circuit, resulting in insufficient penetration depth. Note that a buried arc is a condition in which the wire sinks into the molten pool due to strong arc pressure, generating an arc; generally, the higher the welding current, the stronger the arc pressure.

[0089] (Normal feeding period T Ｐ The period of more than two-thirds of the current is the current non-suppression period T ＩＰ The current non-suppression period T ＩＰ Here, the period during which the wire tip position moves from the uppermost end to the lowermost end is the normal feeding period T Ｐ Refers to...

[0090] Here, explanation will be made with reference to Figures 7 and 8. Figure 7 is a series of photographs taken by a high-speed camera showing an example of the progress of welding in a conventional short-circuit transfer method, along with the advancement or retreat of the welding wire, the current non-suppression period, and the current suppression period, and these are photographs in place of drawings taken at intervals of time for Test No. 24, a reference example described later. Figure 8 is a series of photographs taken by a high-speed camera showing an example of the progress of welding in this embodiment, along with the advancement or retreat of the welding wire, the current non-suppression period, and the current suppression period, and these are photographs in place of drawings taken at intervals of time for Test No. 8, an example described later. As shown in Figure 7, in wire feed control using the conventional short-circuit transfer method, the normal feed period T indicated by "advance" in the figure is Ｐ is approximately 8.4 ms from 0 ms to 8.4 ms, while the normal feeding period T Ｐ During the non-current suppression period TＩＰ is approximately 2.4 ms from 0 ms to 2.4 ms, so the normal feeding period T Ｐ During the non-current suppression period T ＩＰ As can be seen, the proportion of the normal feed period T Ｐ During the non-current suppression period T ＩＰ By controlling the ratio to less than 1 / 2, low-spatter welding is possible, but as a result, the arc pressure does not act on the molten pool, resulting in a shallow penetration depth.

[0091] On the other hand, as shown in FIG. 8, in the wire feed control according to this embodiment, the normal feed period T Ｐ is approximately 8.4 ms from 0 ms to 8.4 ms, while the normal feeding period T Ｐ During the non-current suppression period T ＩＰ is approximately 7.2 ms from 0 ms to 7.2 ms, and the normal feeding period T Ｐ During the non-current suppression period T ＩＰ As can be seen, in the wire feed control according to this embodiment, the proportion of the normal feed period T Ｐ During the non-current suppression period T ＩＰ By controlling the ratio to 2 / 3 or more, sufficient arc pressure will dig into the molten pool as the wire tip approaches the molten pool, resulting in a deep penetration depth.

[0092] Next, preferred conditions in this embodiment will be described in detail.

[0093] As shown in FIG. 9A, the current non-suppression period T ＩＰ is the current suppression period T during which the base current changes to a predetermined current value. ＩＢ The immediately following rising section T Ｕ , the current suppression period T ＩＢ The previous falling interval T Ｄ , and the rising section T Ｕ and the falling interval T Ｄ Current control section T other than Ｃ It is preferable to control the current separately.

[0094] This rising section T Ｕ is a current non-suppression period T ＩＰ The ratio to the rising section T Ｕ / current non-suppression period T ＩＰ ) × 100%” is preferably 20% or less. Ｕ The welding current value rises sharply as shown in FIG. 9A, in other words, during the current non-suppression period T ＩＰ The rising section T Ｕ The ratio may be as close to 0% as possible.

[0095] In addition, the falling interval T Ｄ is the current non-suppression period T ＩＰ The ratio of the falling interval T Ｄ / current non-suppression period T ＩＰ ) × 100% is preferably 20% or less. Ｄ The welding current value falls sharply as shown in FIG. 9A, in other words, during the current non-suppression period T ＩＰ Falling interval T Ｄ The ratio of the rising section T Ｕ and falling section T Ｄ may vary linearly, curvedly or stepwise, or may vary in a combination of these.

[0096] Next, as shown in FIG. 9A, the current control section T Ｃ It is preferable to provide at least two welding current setting values ​​in the welding current setting value I. Here, the two welding current setting values ​​are defined as a first welding current setting value I Ｐ１ and the second welding current setting value I Ｐ２ Let's say.

[0097] When the uppermost position of the welding wire 100 is set as the reference position and the angle is set to 0 degrees, the first welding current setting value I Ｐ１ The timing for setting the first welding current setting value IＰ１ It is preferable to set the end position of the range of the first welding current setting value I to a range of 20 degrees or less. Ｐ１ By setting the end position of the range to a range of 20 degrees or less, it is possible to suppress the oscillation of the droplets that have begun to form, and more stable detachment can be maintained.

[0098] In addition, when the uppermost position of the welding wire 100 is set as 0 deg, the second welding current setting value I Ｐ２ As the timing for setting the second welding current setting value I Ｐ２ It is preferable to set the end position of the range of 135 to 220 degrees. Ｐ２ By setting the end position of the range between 135 and 220 degrees, the arc pressure can be applied to the molten pool effectively, making it possible to obtain a stable penetration depth.

[0099] Furthermore, as shown in FIG. 9B, the welding current setting value I Ｐ２ The end of the range is the current control section T Ｃ The welding current setting value I Ｐ２ When the end position of the range is X degrees, the current suppression period T ＩＢ It is preferable to set the end position of the current suppression period T in the range of (X+100) to (X+220) degrees. ＩＢ By setting the end position of the current suppression period T ＩＢ This is preferable from the viewpoint of stabilizing droplet detachment, since the timing when the most inertial force acts is included within the period.

[0100] First welding current setting value I Ｐ１ The welding current set in is preferably in the range of 250 to 600 A, and the second welding current set value I Ｐ２ The welding current set in the first welding current setting value I is preferably in the range of 300 to 650 A. Ｐ１ and the second welding current setting value I Ｐ２ By setting the set currents in the above ranges, the first welding current set value I Ｐ１ and the second welding current setting value I Ｐ２By providing the second welding current setting value I Ｐ２ The welding current set by is the first welding current set value I Ｐ１ The value is always larger than the welding current set in

[0101] Current control section T Ｃ , specifically, the first welding current set value I Ｐ１ and the second welding current setting value I Ｐ２ It is preferable to set the external characteristics of the welding power source during the period. More specifically, by setting the external characteristics of the welding power source within the range of 0.05 V to 20 V / 100 A, the welding current is changed even when the extension length changes during welding, thereby controlling the arc length to be approximately constant.

[0102] Current non-suppression period T ＩＰ The average current I Ｐ－ＡＶＥ is in the range of 300 to 650 A, and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ In terms of adjusting the droplet size, it is preferable that the current is in the range of 80 to 150 A. ＩＰ is in the range of 3.0 to 12.0 ms, and the current suppression period T ＩＢ From the viewpoint of adjusting the droplet size, it is preferable that the normal feeding period T Ｐ and reverse feeding period T Ｎ The preferred range of is the above-mentioned frequency f and {T Ｎ / (T Ｐ +T Ｎ )) is a period calculated from the respective specified ranges.

[0103] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples, and modifications can be made within the scope of the invention, and all such modifications are within the technical scope of the invention.

[0104] [1. Preliminary Test] First, prior to the main test described below, a preliminary test was conducted to examine the relationship between the number of short circuits and penetration depth. Fig. 10 is a diagram showing the relationship between the number of short circuits and penetration depth. The upper photograph in Fig. 10 is a cross-sectional photograph of a welded portion obtained under welding conditions of a welding current of 309 A, a welding voltage of 36.7 V, and a welding speed of 50 cm / min, with the number of short circuits being 97.7 times / second. The lower photograph in Fig. 10 is a cross-sectional photograph of a welded portion obtained under welding conditions of a welding current of 307 A, a welding voltage of 36.8 V, and a welding speed of 50 cm / min, with the number of short circuits being 9.6 times / second.

[0105] As is clear from these cross-sectional photographs, a correlation is observed between the number of short circuits and penetration depth, and it can be seen that the test example in the lower row, which has a significantly lower number of short circuits, has a deeper penetration of the weld. It was also visually confirmed that the fewer the number of short circuits, the less spatter is generated. In other words, it is believed that a smaller number of short circuits results in a stable penetration depth and reduced spatter. For these reasons, in the following tests, the number of short circuits was used to determine whether a stable penetration depth and reduced spatter were achieved.

[0106] [2. Main Tests] Next, tests of examples and comparative examples shown below were carried out to confirm the effects of the welding control method according to the present invention.

[0107] <Common Welding Conditions> The common welding conditions were as follows: Welding wire: mild steel solid wire Base material: SS400 (general structural rolled steel material JIS G 3101:2004) Welding speed of welding wire: 40 cm / min Welding method: bead-on-plate

[0108] <Evaluation Method> As explained in [1. Preliminary Test] above, since there is thought to be a correlation between the number of short circuits and whether stable penetration depth and reduction of spatter have been achieved, stable penetration depth and reduction of spatter were evaluated based on the number of short circuits. In this test, a short circuit count of 5.0 times / second or less was rated as A (excellent), a short circuit count of more than 5.0 times / second but not more than 10.0 times / second was rated as B (good), and a short circuit count of more than 10.0 times / second was rated as C (poor).

[0109] The test results are shown in Tables 1 and 2, along with welding conditions other than the common test conditions.

[0110]

[0111]

[0112] As shown in Tables 1 and 2, Tests No. 1 to No. 10 are examples that satisfy all of the requirements of the present invention, and the number of short circuits was very small. This indicates that the penetration depth was deep and the amount of spatter generated was small. On the other hand, Tests No. 11 to No. 23 are comparative examples that do not satisfy at least some of the requirements of the present invention, and the number of short circuits was very large in all cases. This indicates that the penetration depth was shallow and the amount of spatter generated was large. In Table 1, "frequency f (Hz)", "(wave height Wh / distance between tip and base metal) x 100 (%)", and "I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )," "T ＩＢ / (T ＩＰ +T ＩＢ )," "T Ｎ + (T Ｐ +T Ｎ ) ", "{T Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}", values ​​that do not satisfy the range of the present invention are underlined. Also, Test No. 24 in Table 1 is a reference example of the feeding process by the conventional short-circuit transfer method described above with reference to FIG. 8, and the normal feeding period T ＰThe period of more than two-thirds of the current is the current non-suppression period T ＩＰ This is an example that does not satisfy the condition of being occupied by.

[0113] Each test is discussed in detail below.

[0114] Test No. 1, which is an example, satisfies all the requirements of the present invention, but in particular, since the frequency f was 60 Hz and satisfied the range of 50 to 150 Hz, an inertial force acted on the tip of the wire, the number of short circuits was small, and it was rated B.

[0115] Test No. 2, an example, satisfied all the requirements of the present invention, but in particular, since the frequency f was 130 Hz and satisfied the range of 50 to 150 Hz, an inertial force acted on the tip of the wire, the number of short circuits was small, and it was rated A.

[0116] Test No. 3, which is an example, satisfies all the requirements of the present invention, but in particular, {(wave height Wh / tip-base metal distance) × 100} is 15%, which satisfies the range of 14 to 35%, so that an inertial force acts on the wire tip, the number of short circuits is small, and it was rated B.

[0117] Test No. 4, an example, satisfied all the requirements of the present invention, but in particular, {(wave height Wh / tip-base metal distance) × 100} was 32%, which satisfied the range of 14 to 35%, so that an inertial force acted on the wire tip, the number of short circuits was small, and it was rated A.

[0118] Test No. 5, which is an example, satisfies all the requirements of the present invention, but in particular, Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )} was 0.67, which satisfies the range of 0.65 to 0.90, so the droplet size was appropriate, the electromagnetic pinch force worked effectively, the number of short circuits was small, and the evaluation was B.

[0119] Test No. 6, which is an example, satisfies all the requirements of the present invention, but in particular, Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ)} was 0.88, which satisfies the range of 0.65 to 0.90, so the droplet size was appropriate, the electromagnetic pinch force worked effectively, the number of short circuits was small, and the evaluation was B.

[0120] Test No. 7, which is an example, satisfies all the requirements of the present invention, but in particular, {T ＩＢ / (T ＩＰ +T ＩＢ )} was 0.31, which satisfies the range of 0.30 to 0.60, so the droplet size was appropriate, the electromagnetic pinch force worked effectively, the number of short circuits was small, and the evaluation was A.

[0121] Test No. 8, which is an example, satisfies all the requirements of the present invention, but in particular, {T ＩＢ / (T ＩＰ +T ＩＢ )} was 0.58, which satisfies the range of 0.30 to 0.60, so the droplet size was appropriate, the electromagnetic pinch force worked effectively, the number of short circuits was small, and the evaluation was B.

[0122] Test No. 9, which is an example, satisfies all the requirements of the present invention, but in particular, {T Ｎ + (T Ｐ +T Ｎ )} was 0.40, which satisfied the range of 0.40 to 0.70, so that the inertial force acted effectively on the tip of the wire, the number of short circuits was small, and the wire was rated A.

[0123] Test No. 10, which is an example, satisfies all the requirements of the present invention, but in particular, {T Ｎ + (T Ｐ +T Ｎ )} was 0.70, which satisfies the range of 0.40 to 0.70, so that the inertial force acts effectively on the tip of the wire, the number of short circuits was small, and the wire was rated A.

[0124] On the other hand, in Test No. 11, which is a comparative example, the frequency f was 45 Hz, which is below the range specified in the present invention, so the inertial force acting on the wire tip was insufficient and the droplets could not be detached, resulting in a large number of short circuits and a rating of C.

[0125] In Test No. 12, which is a comparative example, the frequency f was 155 Hz, which exceeded the range specified in the present invention, so the droplet size was too small, the inertial force acting on the wire tip was insufficient, and the droplets could not be detached, resulting in a large number of short circuits and a rating of C.

[0126] In Test No. 13, which is a comparative example, {(wave height Wh / tip-base metal distance) × 100} was 13%, which is below the range specified in the present invention, so the inertial force acting on the wire tip was insufficient and droplets could not be detached, resulting in a large number of short circuits and a rating of C.

[0127] In Test No. 14, which is a comparative example, {(wave height Wh / tip-base metal distance) × 100} was 38%, which exceeded the range specified in the present invention, and therefore, even with a normal arc length, the number of short circuits increased, resulting in a large number of short circuits and a C rating.

[0128] In Test No. 15, which is a comparative example, {(wave height Wh / tip-base metal distance) × 100} was 13%, which is below the range specified in the present invention, so the inertial force acting on the wire tip was insufficient and the droplet could not be separated. ＩＢ / (T ＩＰ +T ＩＢ )} is 0.22, which is below the range defined in the present invention. ＩＢ In this period, the droplet formed at the tip of the wire does not completely separate, and the current is not suppressed during the period T ＩＰ The welding was prone to separation while receiving the arc reaction force, and the number of short circuits increased, resulting in an increase in spatter and a lack of stable penetration depth, resulting in a high number of short circuits and a rating of C.

[0129] In Test No. 16, which is a comparative example, {(wave height Wh / tip-base metal distance) × 100} is 40%, which is beyond the range specified in the present invention, and therefore, even with a normal arc length, short circuits increased. ＩＢ / (T ＩＰ +T ＩＢ )} is 0.14, which is below the range defined in the present invention. ＩＢ In this period, the droplet formed at the tip of the wire does not completely separate, and the current is not suppressed during the period T ＩＰThe welding was prone to separation while receiving the arc reaction force, and the number of short circuits increased, resulting in an increase in spatter and a lack of stable penetration depth, resulting in a high number of short circuits and a rating of C.

[0130] Test No. 17, which is a comparative example, is Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )} is 0.60, which is below the range specified in the present invention, and therefore the electromagnetic pinch force acting on the droplet is also small. Ｎ / (T Ｐ +T Ｎ )<{T ＩＢ / (T ＩＰ +T ＩＢ )}, which does not satisfy the conditions stipulated in the present invention, the arc force was insufficient when the tip of the wire approached the molten pool before reverse feeding occurred, which made it easier for short circuits to occur and resulted in shallow penetration depth, resulting in a high number of short circuits and a C rating.

[0131] Test No. 18, which is a comparative example, is Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )} was 0.91, which exceeded the range specified in the present invention. Therefore, the droplet size was large, the droplets were repelled and detached by the arc reaction force, and arc interruption and long-term short circuits occurred. As a result, the number of short circuits was high and the test was rated C.

[0132] Test No. 19, which is a comparative example, is ＩＢ / (T ＩＰ +T ＩＢ )} is 0.29, which is below the range defined in the present invention. ＩＢ In this period, the droplet formed at the tip of the wire does not completely separate, and the current is not suppressed during the period T ＩＰ The welding was prone to separation while receiving the arc reaction force, and the number of short circuits increased, resulting in an increase in spatter and a lack of stable penetration depth, resulting in a high number of short circuits and a rating of C.

[0133] Test No. 20, which is a comparative example, is ＩＢ / (T ＩＰ +T ＩＢ)} is 0.64, which is beyond the range defined in the present invention, the electromagnetic pinch force is insufficient, and the current suppression period T ＩＢ In this case, stable detachment was not possible, droplets were detached at unintended times, short circuits occurred, and spatters were generated. Ｎ / (T Ｐ +T Ｎ )<{T ＩＢ / (T ＩＰ +T ＩＢ )}, which does not satisfy the conditions stipulated in the present invention, the arc force was insufficient when the tip of the wire approached the molten pool before reverse feeding occurred, which made it more likely to cause short circuits and resulted in shallow penetration depth, resulting in a high number of short circuits and a rating of C.

[0134] Test No. 21, which is a comparative example, is Ｎ + (T Ｐ +T Ｎ )} is 0.35, which is below the range specified in the present invention, so that a sufficient time required for droplet detachment cannot be obtained, and the current suppression period T ＩＢ In this case, stable detachment was not possible, droplets were detached at unintended times, short circuits occurred, and spatters were generated. Ｎ / (T Ｐ +T Ｎ )<{T ＩＢ / (T ＩＰ +T ＩＢ )}, which does not satisfy the conditions stipulated in the present invention, the arc force was insufficient when the tip of the wire approached the molten pool before reverse feeding occurred, which made it more likely to cause short circuits and resulted in shallow penetration depth, resulting in a high number of short circuits and a rating of C.

[0135] Test No. 22, which is a comparative example, is Ｎ + (T Ｐ +T Ｎ )} was 0.75, which exceeded the range specified in the present invention, so the droplets formed at the wire tip stretched thinly, making it easier for short circuits to occur before the reverse feed period began, and the penetration was shallower, resulting in a large number of short circuits and a rating of C.

[0136] Test No. 23, which is a comparative example, is Ｎ / (T Ｐ +T Ｎ )<{T ＩＢ / (T ＩＰ +T ＩＢ )}, which does not satisfy the conditions stipulated in the present invention, the arc force was insufficient when the tip of the wire approached the molten pool before reverse feeding occurred, which made it more likely to cause short circuits and resulted in shallow penetration depth, resulting in a high number of short circuits and a rating of C.

[0137] The present invention is not limited to the above-described embodiments and examples, and can be modified, improved, etc. as appropriate.

[0138] As described above, the present specification discloses the following:

[0139] (1) In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ A welding control method for controlling a welding operation by switching the normal feed period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ)≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ This configuration makes it possible to achieve both a stable penetration depth and reduced spatter in an arc welding method in which forward and reverse feeding of the wire tip is cyclically repeated.

[0140] (2) The welding control method according to (1), wherein the welding wire feed speed when the tip of the welding wire is located at the uppermost end or the lowermost end is set to a predetermined average feed speed. With this configuration, even if the wire feed speed changes periodically, the wire melting rate and the wire feed speed are balanced, the arc length becomes approximately constant, and stable welding can be continued.

[0141] (3) The current non-suppression period T ＩＰ is the current suppression period T ＩＢ The rising section immediately after that, the current suppression period T ＩＢThe current control section T other than the immediately preceding falling section, the rising section, and the falling section Ｃ The rising section is the current non-suppression period T ＩＰ The falling section is equal to or less than 20% of the current non-suppression period T ＩＰ The welding control method according to (1) or (2), wherein the welding time is 20% or less of the rising section T Ｕ In this case, the droplet size can be adjusted or droplet separation can be promoted. Ｄ In this way, droplet size adjustment can be achieved before reverse feeding takes place.

[0142] (4) The current control section T Ｃ At least two welding current setting values ​​I Ｐ１ , I Ｐ２ When the uppermost end position of the welding wire is set to 0 degrees, the welding current set value I Ｐ１ The end position of the range is set to a range of 20 degrees or less, and the welding current setting value I Ｐ２ The welding control method according to (3), wherein the end position of the range of the first welding current set value I is set in the range of 135 to 220 degrees. Ｐ１ By setting the end position of the range of I to 20 degrees or less, it is possible to suppress the oscillation of the droplet that has started to form, and more stable detachment can be maintained. Ｐ２ By setting the end position of the range between 135 and 220 degrees, the arc pressure can be applied to the molten pool effectively, making it possible to obtain a stable penetration depth.

[0143] (5) The welding current setting value I Ｐ２ The end of the range is the current control section T Ｃ The welding current setting value I Ｐ２ When the end position of the range is X degrees, the current suppression period T ＩＢ (4) The welding control method according to (4), wherein the end position of the current suppression period T is set in the range of (X+100) to (X+220) degrees. ＩＢThe timing when the most inertial force is exerted is included within this period, which allows for stable droplet detachment.

[0144] (6) The welding current setting value I Ｐ１ The set current is set to 250 to 600 A, and the welding current set value I Ｐ２ The welding control method according to (4) or (5), wherein the first welding current setting value I is set to 300 to 650 A. Ｐ１ and the second welding current setting value I Ｐ２ By providing the above, the effect obtained can be further enhanced.

[0145] (7) The current control section T Ｃ The welding control method according to any one of (4) to (6), further comprising providing an external characteristic of the welding power source. With this configuration, even if the extension length changes during welding, the welding current can be changed to control the arc length to be approximately constant.

[0146] (8) The average volume of the droplets detached from the tip of the welding wire is 1.7 to 5.0 mm ３ According to the welding control method of any one of (1) to (7), it is possible to more effectively suppress short circuits, thereby reducing spatter and achieving a stable high penetration depth.

[0147] (9) In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ A welding control device for switching and controlling the normal feed period T Ｐ and the reverse feeding period T ＮThe combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ This configuration makes it possible to achieve both a stable penetration depth and reduced spatter in an arc welding method in which forward and reverse feeding of the wire tip is cyclically repeated.

[0148] (10) A welding power source including the welding control device according to (9). With this configuration, it is possible to achieve both a stable penetration depth and reduced spatter in an arc welding method in which forward and reverse feed of the tip of the wire is periodically repeated.

[0149] (11) A welding system including the welding control device according to (9) or the welding power source according to (10). This configuration makes it possible to achieve both a stable penetration depth and reduced spatter in an arc welding method in which forward and reverse feed of the tip of the wire is periodically repeated.

[0150] (12) In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ a welding control device for controlling the welding system by switching between the normal feed period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period TＮ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ This configuration makes it possible to achieve both stable penetration depth and reduced spatter in an arc welding method in which forward and reverse feeding of the wire tip is cyclically repeated.

[0151] (13) In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎ and controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ A welding method for performing gas metal arc welding while performing welding control by switching between the normal feed period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦IＰ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰ According to this configuration, in an arc welding method in which forward and reverse feeding of the tip of the wire is cyclically repeated, it is possible to achieve both a stable penetration depth and reduced spatter.

[0152] (14) In additive manufacturing using gas metal arc welding to supply a welding current to a welding wire, a forward feeding period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feeding period T Ｎand controlling the welding wire feed speed so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and controlling the welding current during a current non-suppression period T ＩＰ or current suppression period T ＩＢ An additive manufacturing method for performing additive manufacturing while performing welding control by switching to and controlling the normal feeding period T Ｐ and the reverse feeding period T Ｎ The combined period is defined as one cycle, and the frequency f is set to 50 to 150 Hz. ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change width of the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of the tip-base metal distance of the welding wire, and an arbitrary current non-suppression period T ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feeding period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feeding period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ )>{T ＩＢ / (T ＩＰ +T ＩＢ )}, and the normal feeding period T Ｐ The period of two-thirds or more of the current non-suppression period T ＩＰAccording to this configuration, in an additive manufacturing method using an arc welding method in which forward and reverse feed of the wire tip are cyclically repeated, it is possible to achieve both a stable penetration depth and reduced spatter.

[0153] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0154] This application is based on a Japanese patent application (Patent Application No. 2021-152554) filed on September 17, 2021, the contents of which are incorporated by reference into this application.

[0155] 50 Welding system 100 Welding wire 110 Welding robot 111 Welding torch 120 Welding control device 140 Welding power source 150 Controller 200 Work (base material) f Frequency Fave Average feed speed Fw Feed speed command signal (feed speed signal) I Ｂ－ＡＶＥ Current suppression period T ＩＢ Average current I Ｐ－ＡＶＥ Current non-suppression period T ＩＰ Average current I Ｐ１ First welding current setting value I Ｐ２ Second welding current setting value T Ｃ Current control section T Ｄ Falling section T ＩＢ Current suppression period T ＩＰ Current non-suppression period T Ｎ Reverse feed period T Ｐ Positive feed period T Ｕ Rising section Wh Wave height

Claims

1. In gas metal arc welding, in which a welding current is supplied to a welding wire, a forward feed period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feed period T Ｎ and controlling a feed speed of the welding wire so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and ＩＰ or current suppression period T ＩＢ A welding control method for switching and controlling the normal feed period T Ｐ and the reverse feed period T Ｎ The combined period is defined as one cycle, the frequency f of which is 50 to 150 Hz, and the current non-suppression period T ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change in the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of a tip-base metal distance of the welding wire, and ＩＰ and the current suppression period T immediately thereafter. ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feed period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feed period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ ) 〉 {T ＩＢ / (T ＩＰ +T ＩＢ )) and the normal feeding period T Ｐ The current non-suppression period T ＩＰ A welding control method comprising the steps of:

2. A welding control method as claimed in claim 1, wherein the feed speed of the welding wire when the tip of the welding wire is located at the uppermost end or the lowermost end is set to a predetermined average feed speed.

3. The current non-suppression period T ＩＰ is the current suppression period T ＩＢ The immediately following rising section T Ｕ , the current suppression period T ＩＢ The previous falling section T Ｄ , and the rising section T Ｕ and the falling interval T Ｄ Current control section T other than Ｃ The rising section T Ｕ is the current non-suppression period T ＩＰ 20% or less of the falling interval T Ｄ is the current non-suppression period T ＩＰ The welding control method according to claim 1 or 2, wherein the welding speed is 20% or less.

4. The current control section T Ｃ At least two welding current setting values ​​I Ｐ１ , I Ｐ２ When the uppermost end position of the welding wire is set to 0 deg as a reference, the welding current set value I Ｐ１ The end position of the range of the welding current set value I is set within a range of 20 degrees or less. Ｐ２ The welding control method according to claim 3, wherein the end positions of the range are set in the range of 135 to 220 deg.

5. The welding current setting value I Ｐ２ The end of the range is the current control section T Ｃ The welding current setting value I Ｐ２ When the end position of the range is X deg, the current suppression period T ＩＢ The welding control method according to claim 4, wherein the end position of the welding is set in a range of (X+100) to (X+220) degrees.

6. The welding current setting value I Ｐ１ The set current of the welding current set value I is set to 250 to 600 A. Ｐ２ The welding control method according to claim 4, wherein the set current is 300 to 650 A.

7. The welding current setting value I Ｐ１ The set current of the welding current set value I is set to 250 to 600 A. Ｐ２ The welding control method according to claim 5, wherein the set current is 300 to 650 A.

8. The current control section T Ｃ 5. The method of claim 4, further comprising providing an external characteristic of the welding power source.

9. The current control section T Ｃ The method of claim 5, further comprising providing an external characteristic of the welding power source.

10. Current control section T Ｃ The method of claim 6, further comprising providing an external characteristic of the welding power source.

11. The current control section T Ｃ The method of claim 7, further comprising providing an external characteristic of the welding power source.

12. The average volume of the droplet detached from the tip of the welding wire is 1.7 to 5.0 mm ３ The welding control method according to claim 1 or 2, 13. In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feed period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feed period T Ｎ and controlling a feed speed of the welding wire so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and ＩＰ or current suppression period T ＩＢ A welding control device for switching and controlling the normal feed period T Ｐ and the reverse feed period T Ｎ The combined period is defined as one cycle, the frequency f of which is 50 to 150 Hz, and the current non-suppression period T ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change in the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of a tip-base metal distance of the welding wire, and ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feed period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feed period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ ) 〉 {T ＩＢ / (T ＩＰ +T ＩＢ )) and the normal feeding period T Ｐ The current non-suppression period T ＩＰ A welding control device having a function of controlling the welding time so that the welding speed is within the predetermined range.

14. A welding power source comprising the welding control device according to claim 13.

15. A welding system comprising the welding control device according to claim 13 or the welding power source according to claim 14.

16. In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feed period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feed period T Ｎ and controlling a feed speed of the welding wire so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and ＩＰ or current suppression period T ＩＢ A welding system computer including at least a welding control device for controlling the welding control device by switching the normal feed period T Ｐ and the reverse feed period T Ｎ The combined period is defined as one cycle, the frequency f of which is 50 to 150 Hz, and the current non-suppression period T ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change in the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of a tip-base metal distance of the welding wire, and ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feed period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feed period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ ) 〉 {T ＩＢ / (T ＩＰ +T ＩＢ )) and the normal feeding period T Ｐ The current non-suppression period T ＩＰ A program characterized by executing a function of controlling the number of 17. In gas metal arc welding in which a welding current is supplied to a welding wire, a forward feed period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feed period T Ｎ and controlling a feed speed of the welding wire so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and ＩＰ or current suppression period T ＩＢ A welding method for performing gas metal arc welding while performing welding control in which the normal feed period T Ｐ and the reverse feed period T Ｎ The combined period is defined as one cycle, the frequency f of which is 50 to 150 Hz, and the current non-suppression period T ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change in the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of a tip-base metal distance of the welding wire, and ＩＰ and the current suppression period T immediately thereafter. ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feed period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feed period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ ) 〉 {T ＩＢ / (T ＩＰ +T ＩＢ )) and the normal feeding period T Ｐ The current non-suppression period T ＩＰ The welding method is characterized in that the welding control is performed so that the welding current is within the range of 0.5 to 100 .mu.m.

18. In additive manufacturing using gas metal arc welding, in which a welding current is supplied to a welding wire, a positive feed period T is a period during which the tip of the welding wire moves from the uppermost end, which is the position farthest from the base metal, to the lowermost end, which is the position closest to the base metal. Ｐ and a reverse feed period T Ｎ and controlling a feed speed of the welding wire so that the welding current is fed toward the base material while periodically switching between the tip position of the welding wire and the feed speed of the welding wire, and ＩＰ or current suppression period T ＩＢ An additive manufacturing method for performing additive manufacturing while performing welding control in which the positive feed period T Ｐ and the reverse feed period T Ｎ The combined period is defined as one cycle, the frequency f of which is 50 to 150 Hz, and the current non-suppression period T ＩＰ The average current I Ｐ－ＡＶＥ and the current suppression period T ＩＢ The average current I Ｂ－ＡＶＥ The relationship is 0.65≦I Ｐ－ＡＶＥ / (I Ｐ－ＡＶＥ +I Ｂ－ＡＶＥ )≦0.90, a wave height Wh, which is a change in the tip position of the welding wire between the uppermost end and the lowermost end, is set to 14 to 35% of a tip-base metal distance of the welding wire, and ＩＰ and the current suppression period T ＩＢ The relationship is 0.30≦T ＩＢ / (T ＩＰ +T ＩＢ )≦0.60, and the normal feeding period T Ｐ and the reverse feed period T Ｎ The relationship is 0.40≦T Ｎ / (T Ｐ +T Ｎ )≦0.70, and the current non-suppression period T ＩＰ , the current suppression period T ＩＢ , the positive feeding period T Ｐ and the reverse feed period T Ｎ The relationship between Ｎ / (T Ｐ +T Ｎ ) 〉 {T ＩＢ / (T ＩＰ +T ＩＢ )) and the normal feeding period T Ｐ The current non-suppression period T ＩＰ The additive manufacturing method is characterized in that the welding control is performed so that the welding area is occupied by the welding area.

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