Arc start control method, arc start control program, power supply, arc start control system, welding method, and additive manufacturing method

Abstract

To stably transfer a welding time period to a regular welding time period, regardless of a welding method or a welding method.SOLUTION: In a method, which controls an arc start time period after welding is started until a time period for the welding is transferred to a regular welding time period, the arc start time period has at least a first control time period including a time period in which the welding is started and an arc is generated and a time period in which initial molten droplets are formed after the arc is generated, and a second control time period in which a method is changed to a feeding control method in which feeding speed is switched alternately between in a forward feeding time period and a backward feeding time period until the welding is transferred to regular welding in the feeding control method, after the time period in which the initial droplets are formed. The second control time period includes an initial motion interval in which from the start of the second control time period, the welding is maintained for an arbitrary time at an average feeding speed which is lower than the feeding speed of the regular welding or an average feeding speed set value and a transfer interval in which the average feeding speed at the time when the initial motion interval ends is transferred to the feeding speed of the regular welding or the average feeding speed set value, where in the transfer interval, the average feeding speed set value as well as a control condition relating to the feeding control method are changed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an arc start control method, an arc start control program, a power source, an arc start control system, a welding method, and an additive manufacturing method for performing stable arc start regardless of the welding method.

Background Art

[0002] Gas shielded arc welding is performed by various welding methods according to the application, such as a short circuit welding method, a pulse welding method, or a feed control welding method. However, in any method, from the start of welding until reaching a period of stable welding (hereinafter also referred to as the "steady welding period"), there is a transient welding period during which short circuits occur when the arc is generated, arc instability due to the molten pool not being formed, and instability of droplet transfer due to welding condition fluctuations until reaching the set values. Therefore, conventionally, by controlling this transient welding period (hereinafter also referred to as the "arc start period"), short circuit stability at the time of arc generation, improvement of arc instability and droplet transfer instability are achieved, and spatter reduction and a good bead shape are ensured.

[0003] Patent Document 1 discloses control of the arc start period in the case of the short circuit welding method. After instructing the start of welding, during the short circuit period from the occurrence of a short circuit to the occurrence of an arc, the wire feeding speed is set to reverse feeding, and during the arc period from the occurrence of an arc to the next occurrence of a short circuit, the wire feeding speed is set to forward feeding for welding. Then, by switching the wire feeding speed to a constant speed for welding, the amount of spatter generation from the occurrence of an arc until the arc stabilizes can be reduced.

[0004] Patent Document 2 discloses control of the arc start period in the case of pulse welding. When a predetermined time (t1) has elapsed from the short-circuit welding control during the arc start period, the system switches to pulse welding, which outputs a pulse waveform in which the rising and / or falling slopes of the pulse waveform are gentler than those of steady-state welding. After a sufficient molten pool has formed, the system controls the output to display the pulse waveform of steady-state welding. This reduces the amount of spatter generated from the time the arc is generated until the arc stabilizes.

[0005] Patent Document 3 discloses control of the arc start period in a feed control welding method that alternately switches between a forward feed period and a reverse feed period to generate a short-circuit period and an arc period for welding. When starting welding, during the transient welding period until it converges to the steady-state welding period, the absolute values ​​of the reverse feed peak and the absolute values ​​of the forward feed peak of the feed rate are increased over time, thereby stabilizing the welding state when switching from the transient welding period to the steady-state welding period. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-169555 [Patent Document 2] International Publication No. 2012 / 032703 [Patent Document 3] Japanese Patent Publication No. 2021-74732 [Patent Document 4] International Publication No. 2015 / 163101 [Patent Document 5] Japanese Patent Publication No. 2020-49506 [Overview of the project] [Problems that the invention aims to solve]

[0007] As mentioned above, while arc start-up time is controlled in all welding methods, including short-circuit welding, pulse welding, and wire feed control welding, controlling the arc start-up time is most difficult with wire feed control welding. This is because wire feed control welding involves control conditions such as wire frequency and wire amplitude, and requires the control of a wide variety of conditions until the steady-state welding period is reached, making it significantly more difficult to control compared to other methods. As a result, droplet transfer and arc instability are more likely to occur, potentially leading to spatter generation and adverse effects on the bead shape.

[0008] Furthermore, there are different types of feed control welding methods. One type, as exemplified by Patent Document 4, is based on a short-circuit transition pattern that alternately switches the welding wire feed speed between forward and reverse feeding periods to generate short-circuit periods and arc periods (hereinafter also referred to as the "short-circuit feed control method"). Another type, as exemplified by Patent Document 5, is based on a globule transition pattern that alternately switches the welding wire feed speed between forward and reverse feeding periods to suppress the occurrence of short-circuit periods (hereinafter also referred to as the "short-circuit suppression feed control method").

[0009] The short-circuit suppression type feed control method, compared to the short-circuit type feed control method, results in larger droplet sizes at the wire tip. Therefore, the conditions must be gradually changed to increase the droplet size until the steady-state welding period is reached. However, as the steady-state welding period approaches, droplet fluctuations increase, making droplet transfer instability and arc instability more likely. Consequently, spatter generation and bead shape defects are more likely to occur, especially around the transition to the steady-state welding period.

[0010] Here, Patent Document 3 describes a case where a feed control welding method in which controlling the arc start period is difficult is applied, but it is a "short-circuit type feed control method" and does not provide a solution for the "short-circuit suppression type feed control method" in which controlling the arc start period is even more difficult. Furthermore, Patent Documents 1 to 3 are methods for controlling the arc start period according to each welding method, and are not methods for controlling the arc start period that can be commonly applied to multiple welding methods, thus lacking versatility. At the very least, even if the technology of Patent Document 1 or 2 is adapted to a feed control welding method in which controlling the arc start period is difficult, it will not be possible to sufficiently suppress the welding instability that occurs from the arc start period to the steady-state welding period.

[0011] Therefore, the present invention aims to provide an arc start control method, an arc start control program, a power supply, an arc start control system, a welding method, and an additive manufacturing method that enable stable transition to a steady welding period in gas shielded arc welding, regardless of the welding method, even when a short-circuit suppression type feed control method is applied as the welding method. [Means for solving the problem]

[0012] The present invention consists of the following configuration. (1) A method for controlling the arc start period from the start of welding to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An arc start control method characterized by the following.

[0013] (2) An arc start control program for controlling the arc start period from the start of welding to the transition to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. For computers in systems that have at least a power supply, In the transition section, in addition to the average feed rate setting value, a function is provided to vary at least one of the control conditions related to the feed control method. The arc start control program to be executed.

[0014] (3) In welding by gas shielded arc welding method or additive manufacturing utilizing the gas shielded arc welding method, a power source having a function of controlling the arc start period from the start of welding to the transition to the steady welding period, wherein the arc start period includes a first control period including the period from the start of welding to the generation of an arc and the period for forming an initial droplet after the arc is generated, and at least after the period for forming the initial droplet, at least has a second control period from the time of changing to a feeding control method in which the feeding speed is alternately switched between a forward feeding period and a reverse feeding period to the transition to the steady welding period by the feeding control method, wherein the second control period includes a starting period maintaining an average feeding speed lower than the feeding speed or average feeding speed set value of steady welding for an arbitrary time from the start of the second control period, and a transition period transitioning from the average feeding speed at the end of the starting period to the feeding speed or average feeding speed set value of steady welding, wherein the power source varies at least one of the control conditions related to the feeding control method in addition to the average feeding speed set value in the transition period, characterized in that it is a power source.

[0015] (4) In welding by gas shielded arc welding method or additive manufacturing utilizing the gas shielded arc welding method, an arc start control system for controlling the arc start period from the start of welding to the transition to the steady welding period, wherein the arc start control system includes at least a power source, wherein the arc start period includes a first control period including the period from the start of welding to the generation of an arc and the period for forming an initial droplet after the arc is generated, and at least after the period for forming the initial droplet, at least has a second control period from the time of changing to a feeding control method in which the feeding speed is alternately switched between a forward feeding period and a reverse feeding period to the transition to the steady welding period by the feeding control method, wherein the second control period The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An arc start control system characterized by the following:

[0016] (5) A welding method using the gas shielded arc welding method, A system equipped with at least a power supply controls the arc start period from the start of welding to the transition to the steady-state welding period. The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. A welding method characterized by the following.

[0017] (6) Additive manufacturing method utilizing gas shielded arc welding, A system equipped with at least a power supply controls the arc start period from the start of additive manufacturing to the transition to the steady welding period of additive manufacturing. The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An additive manufacturing method characterized by the following. [Effects of the Invention]

[0018] According to the present invention, in gas shielded arc welding, regardless of the welding method, and especially when a short-circuit suppression type feed control method is applied as the welding method, it is possible to prevent welding instability that occurs from the arc start period to the steady welding period, and in particular, it has the effect of suppressing spatter and obtaining a good bead shape. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram showing an example configuration of the welding system according to this embodiment. [Figure 2] This block diagram shows a schematic configuration relating to the control of the welding power supply, welding control device, and servo amplifier in this embodiment. [Figure 3] This graph illustrates the relationship between the wire feeding speed, the wire tip position, and the current detection signal in this embodiment. [Figure 4] This is a timing chart corresponding to this embodiment. [Modes for carrying out the invention]

[0020] Hereinafter, embodiments of the arc start control method, arc start control program, power supply, arc start control system, welding method, and additive manufacturing method according to the present invention will be described in detail with reference to the drawings.

[0021] This embodiment is an example of a case using a welding robot, and the arc start control method, arc start control program, power supply, arc start control system, welding method, and additive manufacturing method according to the present invention are not limited to the configuration of this embodiment. For example, an automatic welding device using a trolley may be applied instead of the welding robot body, or a portable small welding robot may be applied. Furthermore, this embodiment is an example of the short-circuit suppression feed control method, which is the most difficult to control when it comes to arc start control, that is, when welding is performed using the short-circuit suppression feed control method after arc start control. However, the present invention may also be applied to other methods such as the short-circuit feed control method, pulsed MAG welding method, and carbon dioxide welding method.

[0022] In this embodiment, a gas metal arc welding (hereinafter also referred to as "GMAW") method using a welding wire, which is a consumable electrode in gas shielded arc welding, will be described. However, the welding system according to this disclosure is also applicable to additive manufacturing systems that utilize gas metal arc welding. Furthermore, this disclosure also applies to non-consumable electrodes such as TIG welding using filler wire.

[0023] Here, additive manufacturing technology utilizing GMAW is particularly useful in Wire and Arc Additive Manufacturing (WAAM). While the term additive manufacturing is sometimes used in a broader sense as additive manufacturing or rapid prototyping, in this invention, the term additive manufacturing is used consistently. When applying the method of the present invention to additive manufacturing technology, "welding" can be replaced with "welding," "additive manufacturing," or "additive manufacturing." For example, when treated as welding, the term would be "welding conditions," but when using the present invention as additive manufacturing, it can be replaced with "welding conditions." Similarly, when treated as welding, the term would be "welding system," but when using the present invention as additive manufacturing, it can be replaced with "additive manufacturing system."

[0024] Figure 1 is a schematic diagram showing an example configuration of a welding system 50 according to this embodiment. The welding system 50 includes a welding robot 110, a welding control device 120, a welding power supply 140, a controller 150, a servo amplifier 160, a servo motor 170, a push motor 180, and a wire buffer 190. The push motor 180 feeds the welding wire 100.

[0025] The welding power supply 140 is connected to the welding robot 110 via a positive power cable (not shown) to supply power to the welding wire 100, which is a consumable electrode, and is connected to the workpiece (hereinafter also referred to as "base material") 200 via a negative power cable (not shown). This connection is for welding with reverse polarity. To weld with positive polarity, the welding power supply 140 should be connected with the opposite polarity.

[0026] Furthermore, the welding power supply 140 and the push motor 180 are connected by a signal line, allowing control of the welding wire feed speed. In the feed control of this embodiment, the push motor 180 operates only in the forward direction, while the servo motor 170, described later, can be switched between forward and reverse directions.

[0027] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a current-conducting mechanism, i.e., a welding tip, that supplies current to the welding wire 100. The welding wire 100 generates an arc from its tip when current is supplied from the welding tip, and the heat from this arc welds the workpiece 200 that is to be welded. The welding tip is also commonly referred to as a contact tip.

[0028] The welding torch 111 is equipped with a shielding gas nozzle, which is a mechanism for ejecting shielding gas. The shielding gas is not particularly limited, but given the characteristics of the control used in this embodiment, it is preferable that the gas composition takes the form of globule transfer. Specifically, it is preferable that it contains at least one gas with a high potential gradient, such as carbon dioxide, nitrogen, hydrogen, or oxygen. Furthermore, from the viewpoint of versatility, in the case of a mixed gas with argon gas (hereinafter also referred to as "Ar gas"), a system in which at least 10% by volume of carbon dioxide is mixed is more preferable, a system in which 90% by volume of carbon dioxide is mixed is even more preferable, and using carbon dioxide alone is even more preferable. The shielding gas is supplied from a shielding gas supply device (not shown).

[0029] The servo motor 170 is located near the welding torch 111. A servo amplifier 160 connected to the servo motor 170 controls the servo motor 170. In this embodiment, the welding torch 111 is configured to be independent of the servo motor 170, but the torch may also be configured to have the servo motor 170 integrated into the welding torch 111. The servo motor 170 controls the feeding direction by switching between forward and reverse rotation based on forward and reverse feeding commands. The servo amplifier 160 enables high-speed calculation processing and has a forward and reverse feeding command generation unit 161, as described later.

[0030] A wire buffer 190 is positioned between the push motor 180 and the servo motor 170. The push motor 180 feeds the wire only in the forward direction, while the servo motor 170 feeds the wire in both the forward and reverse directions. As a result, the feeding directions of the push motor 180 and the servo motor 170 may differ. This can lead to situations where the wire is subjected to a large load within the feeding path. To ensure proper feeding control even under such feeding conditions, the wire buffer 190 is provided to suppress wire buckling and other issues.

[0031] The welding wire 100 used in this embodiment is not particularly limited. For example, either a solid wire without 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. The diameter of the welding wire 100 is also not particularly limited. In this embodiment, preferably, the upper limit of the diameter is 1.6 mm and the lower limit is 0.8 mm.

[0032] Furthermore, in this embodiment, the specific configuration of the workpiece 200 is not particularly limited, nor are the welding conditions such as joint shape, welding position, and groove shape particularly limited. The welding control device 120 mainly controls the operation of the welding robot 110. Therefore, the welding control device 120 may be referred to as a robot controller. The welding control device 120 holds teaching data that predefines the operation pattern of the welding robot 110, welding start position, welding end position, welding conditions, weaving operation, etc., and controls the operation of the welding robot 110 by instructing the welding robot 110 with these. In addition, the welding control device 120 provides the welding power supply 140 with welding conditions such as welding current, welding voltage, and feed rate during the welding operation according to the teaching data.

[0033] As shown in Figure 1, the welding system 50 of this embodiment has a welding control device 120 that is independent of the welding power supply 140, but it is also possible to have a configuration in which the welding control device 120 is included in the welding power supply 140.

[0034] The controller 150 is connected to the welding control device 120 and performs tasks such as creating or displaying programs for operating the welding robot 110 and inputting teaching data. Information entered by the user into the controller 150 is provided to the welding control device 120. The controller 150 may also have a function for manually operating the welding robot 110. The connection between the controller 150 and the welding control device 120 can be wired or wireless, and there is no particular limitation on the type of connection.

[0035] The welding power supply 140, in response to a command from the welding control device 120, supplies power to the welding wire 100 and the workpiece 200, thereby generating an arc between the welding wire 100 and the workpiece 200. The welding power supply 140 also outputs a control signal for the push motor 180 in response to a command from the welding control device 120.

[0036] Next, the functional configuration of the welding system 50 according to this embodiment will be described in detail with reference to Figures 2 and 3. Figure 2 is a block diagram showing the schematic configuration related to the control of the welding power supply 140, welding control device 120, and servo amplifier 160 in this embodiment. Figure 3 is a graph illustrating the relationship between the wire feeding speed, the wire tip position, and the current detection signal in this embodiment.

[0037] The welding power supply 140 is connected to the welding control device 120 via digital communication, and the welding control device 120 is connected to the servo amplifier 160 via digital communication. In other words, the servo amplifier 160, welding control device 120, and welding power supply 140 are connected in a linear fashion in that order via digital communication. This can be interpreted as the servo amplifier 160 and the welding power supply 140 being indirectly connected via digital communication. Alternatively, the servo amplifier 160, welding power supply 140, and welding control device 120 may be connected in a linear fashion in that order. This can be interpreted as the servo amplifier 160 and the welding power supply 140 being directly connected via digital communication.

[0038] In this embodiment, communication between the welding power supply 140 and the welding control device 120 is performed using CAN (Controller Area Network), which is one of the industrial field networks, and communication between the welding control device 120 and the servo amplifier 160 is performed using EtherCAT (Ethernet for Control Automation Technology) (registered trademark), which is one of the industrial field networks, but the invention is not limited to these.

[0039] (Functional configuration of welding power supply) The control system unit 141 of the welding power supply 140 is executed, for example, through the execution of a program by a welding control device 120 or a computer (not shown). The control system unit 141 of the welding power supply 140 includes a current setting unit 36. In this embodiment, the current setting unit 36 ​​has the function of setting various current values ​​that define the welding current flowing through the welding wire 100. The current setting unit 36 ​​has the function of setting the start time and end time for each period of current control. The current setting unit 36 ​​includes a target current setting unit 36A, a wire tip position conversion unit 36B, and a voltage setting unit 36C. The target current setting unit 36A has the function of setting the start and end times for each of the current control periods: the peak period Dap, the fall period Ddwn, the base period Db, and the rise period Dup. The wire tip position conversion unit 36B has the function of obtaining information on the tip position of the welding wire 100.

[0040] The various conditions can be determined based on, for example, settings entered by the operator in advance, or a pre-prepared waveform control table or welding condition database. The settings, tables, databases, etc., may be stored in any of the components of the welding system 50. For example, the settings, tables, databases, etc., may be stored in the welding control device 120 or the welding power supply 140.

[0041] Furthermore, the various conditions for the peak period Dap, falling period Ddwn, base period Db, and rising period Dup related to the current non-suppression period TIP (the sum of the Dup and Dap periods in this embodiment) and the current suppression period TIB (the sum of the Ddwn and Db periods in this embodiment) can be determined by the waveform control table linear calculation unit 37 based on a pre-prepared waveform control table. In this embodiment, the various conditions referred to are the settings of conditions such as current value, time, or phase.

[0042] The welding current exhibits a pulse waveform that alternately repeats the welding current during the current-unsuppressed period TIP and the current-suppressed period TIB, based on the phase related to the wire tip position (hereinafter referred to as "wire position phase" or "position phase"). In this embodiment, the timing of the peak period Dap, the fall period Ddwn, the base period Db, and the rise period Dup are controlled based on the wire position phase from 0 to 360° (0 to 2π), where 0° is when the wire tip position is closest to the tip side and 180° is when it is closest to the base material side.

[0043] Based on the setting value of the average feed rate Favg in the welding condition information stored by the control system unit 141, the waveform control table linear calculation unit 37 calculates the set current value Iap (hereinafter also referred to as "peak current Iap") for the peak period Dap in the current non-suppression period TIP, and the set current value Ib (hereinafter also referred to as "base current Ib") for the base section Db in the current suppression period TIB, and these are set in the current setting unit 36.

[0044] In this embodiment, the welding current is basically controlled by two values: peak current Iap and base current Ib. Therefore, the start time of the base period Db represents the time when the base current Ib starts, i.e., the base current start time. Also, the end time of the current suppression period Db represents the time when the base current Ib ends, i.e., the base current end time. The start time of the base period Db, the end time of the base period Db, the duration (duration) of the fall period Ddwn, and the duration (duration) of the fall period Ddwn are calculated in the waveform control table linear calculation unit 37. The time when the peak period Dap starts may also be expressed as the peak current start time, and the time when the peak period Dap ends may also be expressed as the peak current end time. As shown in Figure 3, the timing of the peak current end time is preferably determined by the setting period d1 when the wire position phase starts at 0°, and the timing of the peak current start time is preferably determined by the setting period d2 when the peak current end time starts. This setting period is best set using phase. For example, if d1 is set to 190° and d2 to 120°, the peak current will end when the wire position phase is 190° (d1) and the peak current will start when the wire position phase is 310° (d1+d2).

[0045] The various start and end times mentioned above are explained in terms of time. However, the wire position phase value may be used as the basis for processing, and the value may be converted from the wire position phase to time or period (cyc). In other words, since the values ​​of wire position phase, time, and period (cyc) are mutually convertible, control may be performed based on any of these values.

[0046] Furthermore, the wire tip position conversion unit 36B determines the wire tip position based on the phase synchronization signal and phase delay correction signal from the servo amplifier 160. In this embodiment, the wire tip position may be expressed as a wire position phase using an angle (0 to 2π), as described above.

[0047] The phase delay correction signal is output from the phase delay correction unit 38. The phase delay correction unit 38 has a database (not shown in the figure). This database stores data that has been pre-calculated for each welding condition, showing the difference between periodic setting information and the actual forward and reverse feeding operation signals of the servo motor 170. For example, if the welding condition is the wire forward and reverse frequency, the phase delay correction amount is determined based on the above database according to the value of the wire forward and reverse frequency used, and is output from the phase delay correction unit 38 as a phase delay correction signal.

[0048] The main power circuit of the welding power supply 140 consists of a three-phase AC power supply (hereinafter also referred to as "AC power supply") 1, a primary rectifier 2, a smoothing capacitor 3, a switching element 4, a transformer 5, a secondary rectifier 6, and a reactor 7.

[0049] The AC power input from the AC power supply 1 is full-wave rectified by the primary rectifier 2 and then smoothed by the smoothing capacitor 3 to be converted into DC power. Next, the DC power is converted into high-frequency AC power by inverter control by the switching element 4, and then converted into secondary power via the transformer 5. The AC output of the transformer 5 is full-wave rectified by the secondary rectifier 6 and then smoothed by the reactor 7. The output current of the reactor 7 is supplied to the welding tip as the output from the main power supply circuit and energizes the welding wire 100, which is a consumable electrode.

[0050] The welding wire 100 is fed by a push motor 180 and a servo motor 170, generating an arc between it and the base material 200. The forward feeding period, during which the tip of the welding wire 100 is moved toward the base material 200, is denoted as the forward feeding period TP. The reverse feeding period, during which the tip of the welding wire 100 is moved in the opposite direction to the position of the base material 200, is denoted as the reverse feeding period TN. In this embodiment, the feeding motor periodically feeds the welding wire 100, with the forward feeding period TP and the reverse feeding period TN combined forming one cycle. The tip of the welding wire usually refers to the tip of the wire when the presence of molten droplets hanging from the wire tip is ignored. That is, the wire melted by the arc is considered to have immediately moved toward the base material 200.

[0051] The feeding of the welding wire 100 by the push motor 180 is controlled by a control signal based on the push feeder control unit 39. The average feeding speed is approximately the same as the melting speed. In this embodiment, the feeding of the welding wire 100 by the push motor 180 is also controlled by the welding power supply 140.

[0052] Furthermore, the push feeder control unit 39 performs control according to the state of the wire buffer 190. In this embodiment, the wire buffer 190 is provided with a wire slack portion (a gap to which the wire can escape if it becomes loose due to the effects of feeding between the motors) so that a large load is not placed on the wire in the feeding path between the push motor 180 and the servo motor 170. The amount of wire buffer is detected as a rotation angle by an absolute encoder, which is a sensor built into the wire buffer 190. The detected value is converted into an analog signal by the serial-to-analog conversion unit 191, and the electrical angle is calculated by the electrical angle calculation unit. The calculated electrical angle is input to the A / D input unit 40 of the welding power supply.

[0053] A difference signal, obtained by taking the difference between the electrical angle from the A / D input unit 40 and a preset reference value of the electrical angle in the electrical angle adjustment unit 41, is input to the push feeder control unit 39. Based on this difference signal, the push feeder control unit 39 controls the push motor 180 to achieve an appropriate wire buffer amount, thereby performing interference control to prevent excessive load on the feeding system. In this embodiment, interference control is performed as described above, but it is not limited to this. Also, in this embodiment, an absolute encoder built into the wire buffer 190 is used, but it is not limited to this. For example, a rotation angle sensor may be used, in which case the serial-to-analog conversion unit 191 does not need to be provided.

[0054] The current setting unit 36 ​​receives a voltage setting signal Vap from the voltage setting unit 36C, which is the target value of the voltage applied between the welding tip and the base material 200.

[0055] On the other hand, the voltage detection signal Vo is a measured value. In this embodiment, the voltage detection signal Vo passes through a low-pass filter LPF, goes through a disconnection detection unit 33 (described later), and is input to the current setting unit 36 ​​together with the disconnection detection signal DTR (described later). Alternatively, a voltage comparison unit may be provided to amplify the difference between the voltage setting signal Vap and the voltage detection signal Vo, and output it to the current setting unit 36 ​​as a voltage error amplification signal.

[0056] The current setting unit 36 ​​controls the welding current during the peak period Dap so that the arc length (hereinafter also referred to as "arc length") remains constant. Based on the voltage setting signal Vap and the voltage detection signal Vo, the current setting unit 36 ​​determines and sets at least the peak period, rise period, base period, and rise period. The values ​​of the peak current Ip and base current Ib may be reset. A current setting signal CCset corresponding to the set period or value is output to the current error amplification unit (PWM) 34.

[0057] The current error amplification unit 34 amplifies the difference between the current setting signal CCset, which is given as a target value, and the current detection signal Io detected by the current detection unit 31, and outputs it to the inverter drive unit 30 as a current error amplification signal Ed. The inverter drive unit 30 corrects the drive signal Ec of the switching element 4 using the current error amplification signal Ed.

[0058] The current setting unit 36 ​​also receives a detachment detection signal DTR, which is a signal that detects the detachment of molten droplets from the tip of the welding wire 100. The detachment detection signal DTR is output from the detachment detection unit 33. The detachment detection unit 33 monitors the change in the voltage detection signal Vo output by the voltage detection unit 32 and detects the detachment of molten droplets from the welding wire 100 from the change. Note that the detachment detection unit 33 is just one example of a detection means.

[0059] The detachment detection unit 33 detects droplet detachment by comparing, for example, the differential or second differential of the voltage detection signal Vo passed through the LPF with a predetermined threshold value for detection. The detection threshold value is pre-stored in a memory unit (not shown in the figure). The detachment detection unit 33 may also generate a detachment detection signal DTR based on the change in resistance value calculated from the measured voltage detection signal Vo and current detection signal Io.

[0060] The waveform control table linear calculation unit 37 is given the average feed rate Favg of the weld wire 100 being fed. The average feed rate Favg is stored in advance in the feed setting data unit 35. In this embodiment, the feed setting data unit 35 is located within the welding power supply 140, but various information related to the feed setting may be stored within the welding control device 120, and this information may be output from the welding control device 120 to the welding power supply 140.

[0061] The waveform control table linear calculation unit 37 determines values ​​such as the peak current Ip, base current Ib, the time at which the base current Ib starts, and the time at which the base current Ib ends, based on the given average feed rate Favg, and outputs them to the current setting unit 36. As mentioned above, the values ​​of wire position phase, time, and period cyc are mutually convertible, so the setting value of the base start phase may be converted to a value of time or period cyc, and the converted value may be output to the current setting unit 36.

[0062] In this embodiment, the average feed rate Favg is input to the waveform control table linear calculation unit 37. However, a value related to the average feed rate Favg may be input to the waveform control table linear calculation unit 37 as a set value, and the waveform control table linear calculation unit 37 may replace the average feed rate Favg with that set value. For example, if a storage unit (not shown) stores a database of the average feed rate Favg and the average current value that enables optimal welding for that average feed rate Favg, the average current value may be used as the set value, and the set value may be replaced with the average feed rate Favg.

[0063] The feed setting data unit 35 may store setting values ​​such as the average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse period Tf. The wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse period Tf may be determined based on the input average feed speed Favg. The feed setting data unit 35 may also store other setting values ​​as feed setting data. In this embodiment, the value of wire amplitude Wf ​​refers to the wave height Wh shown in Figure 3. That is, the set value of wire amplitude Wf ​​is equal to the wave height Wh.

[0064] In this embodiment, the period during which the feeding speed is greater than the average feeding speed Favg is defined as the positive feeding period, and the period during which the feeding speed is less than the average feeding speed Favg is defined as the negative feeding period, resulting in a feeding method (hereinafter abbreviated as "amplitude feeding") in which positive and negative feeding periods alternate. The period during which the feeding speed is less than the average feeding speed Favg refers to a feeding speed less than the average feeding speed Favg, and includes negative feeding speeds, i.e., speeds at which the wire tip moves in the opposite direction to a certain position on the base material 200. The wire amplitude Wf ​​gives the range of change with respect to the average feeding speed Favg, and the wire forward / reverse period Tf gives the time of change in wire amplitude, which is the repeating unit. The wire forward / reverse frequency Sf is the reciprocal of the wire forward / reverse period Tf.

[0065] The average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse period Tf stored in the feed setting data unit 35 are input from the digital communication unit 42 to the digital communication unit 122 of the welding control device 120. In this embodiment, this feed setting data is communicated via CAN communication.

[0066] The welding sequence unit 43 processes each task in the following order based on teaching data: idle, gas flow, arc start, welding, and anti-stick. In Figure 2, for convenience, the welding condition information held by the welding control device 120 is enclosed in a dashed line within the welding power supply 140.

[0067] (Functional configuration of welding control device) As described above, the digital communication unit 122 of the welding control device 120 receives feed setting data such as the average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse period Tf from the feed setting data unit 35 of the welding power supply 140 via CAN communication. The welding control device 120 has a digital communication unit 123 for outputting this feed setting data to the digital communication unit 162 of the servo amplifier 160. In this embodiment, the digital communication unit 123 of the welding control device 120 and the digital communication unit 162 of the servo amplifier 160 are connected by EtherCAT® communication.

[0068] (Servo amplifier functional configuration) The digital communication unit 162 of the servo amplifier 160 receives feed setting data such as the average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse period Tf via EtherCAT® communication. The forward / reverse feed command generation unit 161 of the servo amplifier 160 generates a feed command for forward or reverse feed based on the setting information, i.e., the feed setting data, input via digital communication. The forward / reverse feed command generation unit 161 calculates the amplitude feed speed Ff from the wire amplitude Wf ​​and wire forward / reverse period Tf, and outputs a feed speed command signal Fw to the servo motor 170 based on the amplitude feed speed Ff and the average feed speed Favg.

[0069] In this embodiment, the feed rate command signal Fw is expressed by the following equation. Fw=Ff+Favg...Formula (A)

[0070] Furthermore, the forward / reverse feeding command generation unit 161 may detect at which wire position phase of amplitude feeding detachment occurred based on the detachment detection signal DTR provided by the detachment detection unit 33. However, the feeding speed command signal Fw represented by equation (A) is limited to cases where detachment of a molten droplet from the tip of the welding wire 100 is detected within the assumed period. If detachment of a molten droplet is not detected within the assumed period, the forward / reverse feeding command generation unit 161 may switch the feeding speed command signal Fw to feeding control at a constant speed. For example, the forward / reverse feeding command generation unit 161 switches the feeding speed command signal Fw to feeding at the average feeding speed Favg. The switch from feeding at the average feeding speed Favg to the feeding control represented by equation (A) is determined according to the timing at which detachment of a molten droplet is detected.

[0071] The servo amplifier 160 controls the inverter of the servo motor 170 based on the feed speed command signal Fw. The synchronous signal generation unit 163 of the servo amplifier 160 outputs a phase synchronous signal to the welding power supply 140. This phase synchronous signal is generated based on the feed speed command signal Fw.

[0072] Furthermore, the welding power supply 140 and the synchronization signal generation unit 163 of the servo amplifier 160 may be connected by at least analog input / output. In this case, the welding power supply 140 receives the synchronization signal from the servo amplifier 160 via analog input / output. By transmitting feed setting data such as the average feed speed Fabag, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse period Tf via digital communication, while transmitting the synchronization signal via analog communication, digital and analog communication can be efficiently used depending on the application.

[0073] Here, the phase related to the feed speed command signal Fw (hereinafter also referred to as the "feed speed phase") is set to 0° at the start of forward feeding, 180° (π) at the end of forward feeding and the start of reverse feeding, and 360° (2π) at the end of reverse feeding. In this embodiment, the phase synchronization signals are a feed speed phase synchronization signal and a wire position phase synchronization signal. The feed speed phase synchronization signal is a synchronization signal that turns ON during the forward feeding period (positions 0 to π) and OFF during the reverse feeding period (positions π to 2π). On the other hand, the wire position phase synchronization signal is a synchronization signal that turns ON during the period when the wire is closer to the base material 200 side than the center position of the wave height when the wire is being fed forward or backward (positions 0.5π to 1.5π) and OFF during the period when the wire is closer to the tip side than the center position of the wire amplitude (positions 1.5π to 0.5π). Based on this phase synchronization signal and the aforementioned phase delay correction amount, the wire tip position conversion unit (deg) 36B in the welding power supply 140 determines the tip position of the welding wire 100, i.e., the wire position phase.

[0074] <Arc start control> Next, the arc start control related to the present disclosure will be described. Figure 4 is a timing chart corresponding to this embodiment.

[0075] Arc start control consists of two control periods: the first control period is from the arc start signal (hereinafter also referred to as the welding start signal) St until initial droplet growth and short circuit; and the second control period is from after initial droplet formation until the start of steady-state welding. The feed control method is applied during the second control period. The first and second control periods will be explained in detail below.

[0076] <First control period> The first control period from time t1 to t10 shown in Figure 4 includes control until an arc is generated and control until the initial droplets necessary to transition to the second control period, which will be described later are generated. While there are no particular restrictions on the methods of these controls, it is preferable to control them as follows.

[0077] (Control until the arc is generated: time t1~t8) When the welding start signal St is input and the welding sequence unit 43 enters the arc start state at the welding position, the welding wire is fed toward the base material, and after the welding wire and the base material come into contact, a short circuit occurs, generating the initial arc. If proper control is not performed at this stage, there is a risk of wire breakage or failure of the initial arc.

[0078] (Control of wire feed speed between time t1 and t8) At time t1, the welding start signal St is turned ON. At time t2, the welding wire is fed forward at the welding position towards the base metal at a preset initial feed rate. If this initial rate is too high, the welding wire will push too hard against the base metal, causing wire buckling and torch vibration. Therefore, a lower initial feed rate is preferable. It is also advisable to change the initial feed rate according to the type of steel and wire diameter of the wire being used.

[0079] After the welding wire and the base material come into contact at time t2, the initial feeding speed, or a feeding speed lower than the initial feeding speed, is maintained at time t6, the end time of the second welding current control section, while controlling the welding current as described later. This preheats the welding wire and prevents it from melting. In this embodiment, the initial feeding speed is maintained until time t6.

[0080] At time t6, the wire feed speed is reversed at a predetermined feed speed. By reversed the wire feed speed until a predetermined time t8, the initial arc can be generated smoothly, preventing initial arc failure. In other words, the initial arc is generated during the reverse feed period, from t6 to time t8. The feed speed and time for reverse feed can be set in advance. A negative value for the wire feed speed Fw indicates reverse feed, while a positive value indicates forward feed. If the reverse feed speed is too fast or the reverse feed time is too long, the arc length may become excessively large, potentially leading to arc instability or arc breakage. Therefore, it is preferable to set the reverse feed speed to be slower than -25m / min and the reverse feed time to 15ms or less. This prevents wire breakage and allows for the generation of the initial arc without failure.

[0081] (Control of welding current between time t1 and t8) At time t2, the welding wire and the base material come into contact, and after time t3, when the current flow is determined, constant current control is implemented. A first section is established in which the welding current is controlled to a predetermined minimum current (first welding current) to maintain the welding current I0 for a certain period of time until time t4. The current flow determination can be made by setting a threshold of, for example, a few amperes, and determining that current has flowed when the threshold is exceeded.

[0082] It is known that a preheating period for the wire is provided before the initial arc is generated to prevent wire melting. In the initial stage when the welding wire and base material come into contact, the wire is hard at room temperature, and a pressing force is applied to the base material according to the initial feed rate. Therefore, if the current conditions for preheating the wire are applied immediately after contact, the wire will soften rapidly, making it more likely to melt. In this embodiment, a first section is provided before entering the wire preheating section, which will be described later. By applying a very small current for a certain period in the first section and gradually raising the temperature of the wire, it is possible to prevent wire melting in the initial stage when the welding wire and base material come into contact.

[0083] Furthermore, the welding current I0 in the first section is preferably set to 5A or less, and more preferably to 3A or less, in order to prevent wire breakage. Also, the welding current I0 in the first section is preferably 1A or more, in order to prevent wire buckling. Furthermore, the duration of the first section is preferably 0.5ms or more, and more preferably 0.8m or more, in order to prevent wire breakage. It is also preferably 1.5ms or less, in order to prevent wire buckling. Note that the current and duration settings for the first section will vary depending on various conditions, so it is advisable to build a database so that the current and duration conditions for the first section can be extracted according to the conditions.

[0084] As mentioned above, it is preferable to provide a second section after the first section for preheating the wire. The second section may consist of a rise section that increases the wire temperature to a predetermined preheating condition and a maintenance section that maintains the predetermined preheating condition. In the rise section of the second section, the slope of the wire preheating condition should be predetermined with the welding current I0 as the target value. This allows the wire to transition to the predetermined preheating condition without the wire fusing.

[0085] Furthermore, from the viewpoint of ease of control, it is preferable to set the amount of change of the slope at each predetermined control period (A / 10μs), but it is also possible to determine the amount of change (A / cyc) for each wire forward and reverse frequency. This also applies to other slopes set in this embodiment.

[0086] The maintenance section of the second section is preferably maintained at a predetermined constant welding current value. In this embodiment, which applies to mild steel and wire diameters of 0.8 to 1.4 mmφ, it is preferable to set it in the range of 30 to 80 A. The end time of the maintenance section of the second section, i.e., the end time of the second section, time t6, is determined by pre-setting the elapsed time from the start of the second section. In this embodiment, which applies to mild steel and wire diameters of 0.8 to 1.4 mmφ, it is preferable to set it in the range of 10 to 24 ms, and even more preferable to set it in the range of 14 to 20 ms.

[0087] As described above, by establishing a second interval, the initial arc can be stably generated between times t6 and t8. Note that the current and time settings for this second interval will vary depending on various conditions; therefore, a database should be built to allow extraction of the appropriate current and time settings for the second interval according to the specific circumstances.

[0088] (Control of arc voltage between time t1 and t8) In this embodiment, as described above, constant current control is used, so the arc voltage fluctuates in accordance with the controlled welding current. In other words, arc voltage control is not required between times t1 and t8. Alternatively, after the arc is generated at time t7, the control may be switched to constant voltage control, and the arc voltage may be controlled so that the arc length remains constant until time t8.

[0089] (Control until the initial droplet is formed and the second control section begins: between time t8 and t10) This control process generates an initial arc and forms initial droplets as a preliminary step before entering the second control period, which will be described later. If this control is not performed properly, there is a risk of a long-term short circuit occurring in the initial stage of the second control period, when the feed control method is applied, which could lead to an increase in sputtering.

[0090] (Control of wire feeding speed between time t8 and t10) At time t8, wire feeding is stopped (wire feeding speed Fw = 0 m / min) until time t9, when the current control described later is completed, thereby melting the tip of the welding wire and forming an initial droplet. That is, the period from time t8 to t9 is the initial droplet formation period, and the wire feeding speed Fw and welding current I0 are controlled during this time. After the initial droplet is formed, the wire is fed forward at a predetermined feeding speed until time t10, when the short-circuit detection signal Sd becomes high.

[0091] At time t10, the second control period, described later, is entered, and by reversing the wire after the short circuit, the feed control method can be stably switched to without sputtering. Although it is also possible to enter the second control period by reversing the feed rate after the formation of the initial droplets at time t10, it is more preferable to enter the second control period after the short circuit of the initial droplets at time t10, as this allows for a more stable entry into the second control period.

[0092] (Control of welding current between time t8 and t10) At time t8, the welding current I0 melts the tip of the welding wire with a predetermined current and time, forming an initial droplet and expanding the molten pool. The welding current and time vary depending on various conditions such as the steel type and wire diameter of the welding wire, so appropriate conditions should be set as needed. In this embodiment, which targets mild steel and wire diameters of 0.8 to 1.4 mmφ, it is preferable to set the welding current I0 to 100 to 140 A and the time to 10 to 30 ms. This allows for stable formation of the initial droplet without fluctuation and obtains a molten pool with the amount of melting necessary to stabilize the second control period described later. Note that these welding current and time settings differ depending on various conditions, so it is advisable to build a database so that the welding current and time conditions can be extracted according to the conditions.

[0093] (Second control period) The start timing of the second control period may be immediately after the initial droplets formed in the first control period have short-circuited, or immediately after the initial droplets have reached any desired size. In this embodiment, the start timing of the second control period is set to immediately after the initial droplets formed in the first control period have short-circuited, and the feed control is changed accordingly.

[0094] The second control period includes an initial control section to stabilize the feed control method and a transitional control section to stabilize into steady-state welding. Here, the initial control section is the period from time t10 to t12 in Figure 4, and the transitional section is the period from time t12 to t13 in Figure 4. By performing the control described below during these sections, excessive short circuits, droplet oscillation, and arc deflection can be suppressed, thereby enabling steady-state welding without bead appearance defects or increased spatter.

[0095] (Initial period: from time t10 to t12) At time t10, the feed control method is switched to. The welding control method may be a short-circuit feed control method or a short-circuit suppression feed control method, but it is preferable to use the short-circuit suppression feed control method to prevent excessive short circuits, and in this embodiment, the short-circuit suppression feed control method is applied. The initial section is a control section for stabilizing the feed control method, and consists of a rise section that suppresses transient instability when changing to the feed control method and a maintenance section that stabilizes the feed control itself.

[0096] In Figure 4, the wire feed speed Fw is shown by a solid line, and the average feed speed is shown by a dashed line. In the initial rise phase, when a short circuit is detected at time t10, the welding wire is reversed, and the feed speed is changed to a predetermined initial average feed speed until it reaches a predetermined average feed speed for the initial maintenance phase at time t11. By setting the initial average feed speed lower than the average feed speed for the initial maintenance phase, stable arc generation after the short circuit is resolved and an appropriate arc length can be ensured after arc generation. It is preferable to set the initial average feed speed in the range of -15 to 2 m / min.

[0097] Furthermore, at time t10, in addition to the average feed speed condition, at least one of the following conditions—wire forward / reverse frequency, wire amplitude, peak period set current, peak period set voltage, wire position at the start of the peak period, and wire position at the end of the peak period—may be set to a value different from the initial section maintenance unit condition and vary until the initial section maintenance unit is reached. For example, at time t10, only during reverse feed immediately after a short circuit, the wire amplitude may be set to a value at least twice that of the maintenance unit condition in the initial section to ensure the arc length.

[0098] The time for the initial rise phase can be predetermined by setting either a slope or a time, but it is preferable to set the slope in advance for ease of control. Furthermore, for ease of control, it is preferable to set the amount of change for the slope for each cycle (cyc) in the wire forward and reverse frequencies, but it is also possible to determine the amount of change (mpm / μsec) for each predetermined control cycle (μsec).

[0099] The initial phase maintenance section is a control section for stabilizing the feed control method, and maintains an average feed speed lower than the average feed speed conditions during steady-state welding for a certain period of time. By providing this control section, droplet transfer due to feed control can be stabilized, preventing short circuits that occur irregularly over a long period (hereinafter also referred to as long-term short circuits), thereby reducing spatter and ensuring a good bead shape.

[0100] Note that the average feed rate setting value F in the initial section maintenance unit. W-AVE1 This is the average feed rate setting value F for steady-state welding. W-AVE2 Ratio to (F W-AVE1 / F W-AVE2 ) is preferably 0.9 or less, and particularly preferably in the range of 0.2 to 0.7. For example, the average feed rate setting value F for steady-state welding. W-AVE2 If the rate is 16 m / min, the average feed rate setting value F in the initial section maintenance unit. W-AVE1It is preferable to set the average feed rate within the range of 3.2 to 11.2 m / min. Furthermore, since the optimal value for stable droplet transfer changes depending on the average feed rate, at least one of the conditions closely related to the average feed rate—wire forward / reverse frequency, wire amplitude, peak period setting current, peak period setting voltage, wire position phase at the start of the peak period, and wire position phase at the end of the peak period—may be set to a value different from the conditions for the initial period maintenance section, and may be varied in the transition section described later until the steady-state weld is reached. In this case, in addition to the average feed rate setting value, it is necessary to combine at least one of these conditions as a condition to be varied.

[0101] The initial phase includes a maintenance section (times t11 to t12) that maintains the average feed rate setting value at a predetermined value. In the maintenance section, the end of the initial phase may be determined based on at least one of the arc voltage and arc length.

[0102] (Transition period: the period from time t12 to t13) During the transition period, the average feed rate setpoint is varied. Other control conditions besides the average feed rate setpoint may also be varied during the transition period. The control conditions other than the average feed rate setpoint that are varied during the transition period are: • Wire frequency when the forward and reverse transmission periods constitute one cycle. Wire amplitude, • Start timing of conditions controlled according to wire position phase or feed rate phase, • The termination timing of the conditions controlled according to the wire position phase or feed speed phase. • Welding current setting value, • Arc voltage setting value, It is at least one of the following.

[0103] The conditions controlled according to the wire position phase or feed rate phase include at least the welding current I0. The control of the welding current I0 is a control that switches the welding current I0 between a suppression period and an unsuppression period according to the wire position phase or feed rate phase. In this case, the control conditions that cause the average feed rate to vary in the transition section, other than the average feed rate set value, may be at least the start timing of the unsuppression period of the welding current I0 and the end timing of the unsuppression period of the welding current I0.

[0104] During the transition section, the set value of the control condition to be varied may be varied according to at least one of the following: a predetermined period unit and a wire frequency unit where the forward and reverse periods constitute one period.

[0105] During the transition section, the average feed rate setting increases linearly, curvedly, or in a stepwise manner. The wire frequency increases linearly, curvedly, or in a stepwise manner. The wire amplitude decreases linearly, curvedly, or in a stepwise manner.

[0106] During the transition period, the control conditions are varied based on a predetermined time or a predetermined slope value.

[0107] The wire position phase at the start of the peak period and the wire position phase at the end of the peak period are conditions specific to the short-circuit suppression type feed control method. When applying the short-circuit suppression type feed control method, which controls the current according to the wire position, it is even more preferable to set the conditions for the wire position at the start of the peak period and the wire position at the end of the peak period in the initial section maintenance unit and to vary them in the transition section described later until the steady-state welding section is reached. The effects of each condition related to the wire forward / reverse frequency, wire amplitude, set current for the peak period, set voltage for the peak period, wire position phase at the start of the peak period, and wire position phase at the end of the peak period will be explained below.

[0108] (Wire forward and reverse frequencies) The wire forward and reverse frequencies in the initial welding section are set lower than those in the steady-state welding section. This has the effect of suppressing long-term short circuits and droplet lifting, and stabilizing droplet transfer. To obtain the above effect, it is more preferable to set the frequencies to 0.8 times or less of the steady-state welding conditions.

[0109] (Wire amplitude) The wire amplitude in the initial welding section is set to be greater than the conditions in the steady-state welding section. This suppresses droplet oscillation, preventing long-term short circuits and droplet lifting, thus stabilizing droplet transfer. To obtain the above effect, it is more preferable to set the amplitude to 1.2 times or more than the steady-state welding conditions.

[0110] (Set current during peak period) The current set for the peak period in the initial phase maintenance section is set lower than the conditions in the steady-state welding section in order to balance the wire melting. This has the effect of suppressing droplet lifting and stabilizing droplet transfer. Preferably, when the wire speed is slower than a certain level, the current set for the peak period in the initial phase maintenance section may be set lower.

[0111] (Setting voltage during peak period) The peak voltage in the initial welding section is set higher than the peak current in the steady-state welding section. This ensures sufficient arc length and suppresses long-term short circuits. For example, the ratio of "peak voltage / peak current" in the initial welding section should be set to be greater than the ratio of "peak voltage / peak current" in the steady-state welding section.

[0112] (Timing of wire position phase at the start of the peak period and wire position phase at the end of the peak period) The wire position phase at the start of the peak period and / or the wire position phase at the end of the peak period in the initial welding section should be set earlier than the conditions in the steady-state welding section. This stabilizes droplet transfer and reduces spatter. If the current phase is slow, droplet detachment is delayed, and the droplets are more likely to float due to the upward force of the arc.

[0113] As described above, the initial period maintenance unit can stabilize droplet transfer, i.e., stabilize the feed control method during the arc start period, by changing the setting value of at least one of the above conditions in addition to the average feed rate setting value. It is even preferable to change all of the above conditions.

[0114] Furthermore, the initial section maintenance unit may be configured to maintain control for a predetermined period of time, as in this embodiment. The predetermined time should be determined by the initial section maintenance unit after investigating the time it takes for the arc length to stabilize. Alternatively, the termination time may be determined after it has been determined that the arc length has stabilized. There are no particular restrictions on the method for determining the arc length, but it may be determined by monitoring the arc voltage V0 (detected voltage).

[0115] (Transition period: the period from time t12 to t13) The transition section is a transient period during which the conditions of the initial section maintenance are varied until steady-state welding conditions are reached. Preferably, the conditions to be varied include, in addition to the average feed rate setting, at least one of the following conditions to be varied: wire forward / reverse frequency, wire amplitude, peak period setting current, peak period setting voltage, wire position at the start of the peak period, and wire position at the end of the peak period. The amount of variation is preferably set in advance by setting the time of the transition section, and it is preferable that it varies linearly toward the target value of steady-state welding conditions, but it may also vary in a curved manner (exponentially increasing or decreasing) or in steps. From the viewpoint of making it easier to stabilize the arc length, it is more preferable to set it to vary linearly or curved manner (exponentially increasing or decreasing). As the average feed rate setting changes, the conditions related to the average feed rate setting (at least one of the following: wire forward / reverse frequency, wire amplitude, peak period setting current, peak period setting voltage, wire position where the peak period begins, and wire position where the peak period ends) also change to an appropriate value. This allows for stable droplet transfer even during transient periods, ensuring reduced spatter and a good bead shape until steady-state welding is achieved.

[0116] (Steady welding section: from time t13 onwards) The above control enables arc starting that reduces spatter and ensures a good bead shape, even when steady-state welding is performed using a feed control method. It is particularly suitable when steady-state welding is performed using a short-circuit suppression type feed control method. Furthermore, since the transient period of arc starting has passed by time t13, it can be applied even if steady-state welding is performed using a short-circuit welding method, MAG welding method, or pulsed MAG welding method. For example, feed control can be stopped at time t13, and the welding can be switched to a short-circuit welding method, MAG welding method, pulsed MAG welding method, etc. In other words, this embodiment can be said to be an arc starting control method that can be applied regardless of the welding method of steady-state welding.

[0117] <Example of arc start control method processing> Next, an example of arc start control according to this embodiment will be described. In this example, the welding wire is a mild steel solid wire with a wire diameter of 1.2φ and a protrusion of 25mm. The time changes of the welding start signal St, the wire feeding speed Fw, the welding current I0, the arc voltage V0, and the short-circuit detection signal Sd (high indicates a short circuit) are shown.

[0118] (First control period: time t1~t10) [(1) Period before time t1: Waiting time] During the period prior to time t1, the welding sequence unit 43 is in an idle state, and the welding start signal St is at a low level. Since welding is stopped, the wire feed speed Fw, welding current I0, and arc voltage V0 are 0, and other signals are also at a low level.

[0119] [(2) Period from time t1 to t2] At time t1, when the welding start signal St changes to a high level, the welding robot 110 moves to the welding start position according to the teaching program. When the welding torch 111 arrives at the welding start position due to the movement of the welding robot 110, the welding sequence unit 43 enters a gas flow state and shielding gas flows (pre-flow). After the shielding gas flows for a certain period of time, the welding sequence unit 43 transitions to an arc start state, and at time t2, the welding power supply 140 outputs an arc voltage V0 (detection voltage). At this time, the arc voltage V0 is the no-load voltage.

[0120] [(3) Period from time t2 to t3] After the welding power supply 140 outputs an arc voltage that is a set voltage based on the arc voltage V0, the welding wire 100 is fed toward the base material 200. In this embodiment, the wire feeding speed Fw is kept constant at a predetermined feeding speed value (m / min) until time t6. At time t3, when the welding wire 100 comes into contact with the base material 200 (short circuit), the arc voltage V0 drops from the no-load voltage to a small voltage value of a few volts. At this time, the welding power supply 140 detects the short circuit condition based on the drop in voltage and changes the short-circuit detection signal Sd to a high level.

[0121] [(4) Period from time t3 to t4] At time t3, after a short circuit, the current discrimination signal Cd becomes high upon energization, and if the welding current I0 (detected current) exceeds 3A, the welding power supply 140 is controlled by constant current control to keep the welding current I0 (detected current) constant at a predetermined value of 5A or less from time t3 to time t4, which is a predetermined time (msec) later.

[0122] [(5) Period from time t4 to t5] This is the wire preheating period. At time t4, the welding power supply 140 increases the welding current I0 using constant current control so that the predetermined welding current value (A) is increased at a rate of increase (A / μs) equal to the target value. The time when the predetermined welding current value is reached is t5.

[0123] [(6) Period from time t5 to t7] The retract start operation is performed after the wire preheating maintenance time has elapsed. The welding power supply 140 maintains a predetermined welding current value by constant current control from time t5, and at time t6, after a predetermined time has elapsed since the rise of the welding current I0 at time t4, the wire feeding speed Fw is changed from forward feeding to reverse feeding, and the welding wire is pulled back to forcibly resolve the short circuit (setting the short circuit detection signal Sd to a low level), and the initial arc is generated at time t7. When the initial arc is generated, the arc voltage V0 increases from the low voltage during the short circuit to an arc voltage value of several tens of volts.

[0124] [(7) Period from time t7 to t8] This is the start time for the formation of the initial droplet. The welding power supply 140 changes the wire feeding speed Fw to 0 m / min at time t8, a predetermined time after the wire feeding speed Fw was changed to reverse feeding at time t6, and stops the wire feeding.

[0125] [(8) Period from time t8 to t9] This is the initial droplet formation period. At time t8, when wire feeding is stopped, the welding power source 140 changes the welding current I0 to a predetermined value and maintains the welding current I0 at the predetermined value until time t9, which is after a predetermined period of time.

[0126] [(9) Period from time t9 to t10] This is the period from the completion of initial droplet formation to the preparation for wire feeding. At time t9, the welding power supply 140 reduces the welding current I0 and changes the wire feeding speed Fw from a stopped state (0m / min) to positive feeding, maintaining this until time t10 when the short-circuit detection signal Sd reaches a high level.

[0127] (Second control period: time t10~t11) [(10) Period from time t10 to t11] This is the initial startup phase. At time t10, the welding power supply 140 changes its wire feeding control method to alternately switch the wire feeding speed Fw between forward feeding and reverse feeding phases. The welding power supply 140 then changes the average feeding speed to 0 m / min and the other conditions to those of the initial maintenance phase, first feeding the wire in reverse to resolve the short circuit.

[0128] After the short circuit is resolved, under the conditions of the initial section maintenance unit, the welding power supply 140 is increased to an average feed speed that meets the predetermined average feed speed conditions of the initial section maintenance unit, based on a predetermined inclination. At this time, the time when the predetermined average feed speed of the initial section maintenance unit is reached is defined as time t11. Note that, considering the wire melting balance, not only the wire speed but also the peak current may be changed according to the passage of time.

[0129] [(11) The period from time t11 to t12] This is the initial maintenance phase. From time t11 to time t12, the welding power supply 140 is maintained according to the predetermined conditions and duration of the initial maintenance phase.

[0130] [(12) Period from time t12 to t13] At time t12, the welding power supply 140 changes the conditions of the initial section maintenance unit to the pre-set welding conditions for steady-state welding. The amount of change is determined by the slope of the target value and a predetermined time. The slope changes every 100 μsec, which is a predetermined period, for the average feed speed, wire amplitude, peak period set current, and peak period set voltage, while the wire frequency, wire position at the start of the peak period, and wire position at the end of the peak period change linearly with each forward and reverse wire cycle.

[0131] [(13) After time t13: steady welding] At time t13, the welding sequence unit 43 changes from the arc start state to the welding in progress state. From time t13 onward, welding is performed using the welding conditions for steady-state welding, based on the welding condition information and waveform control table pre-set in the welding control device 120.

[0132] The operator can pre-set the average feed rate of the initial section maintenance unit. Based on this set average feed rate, the waveform control table linear calculation unit 37 extracts the welding conditions of the initial section maintenance unit and the amount of change (slope) in the transition section corresponding to the set average feed rate, and outputs them to the current setting unit 36.

[0133] The present invention is not limited to the embodiments described above. It is also intended and within the scope of protection to be provided for the combination of each configuration of the embodiments, as well as for modifications and applications by those skilled in the art based on the description in the specification and well-known art.

[0134] As described above, the following matters are disclosed in this specification:

[0135] (1) A method for controlling the arc start period from the start of welding to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An arc start control method characterized by the following. This arc start control method allows for a stable transition to a steady-state welding period in gas-shielded arc welding or additive manufacturing utilizing the gas-shielded arc welding method, regardless of the welding method or bonding method.

[0136] (2) The feeding control method during the second control period is: The forward and reverse transmission periods constitute one cycle. The conditions for control according to the wire position phase or feed speed phase in the aforementioned cycle are: Control at least one of the following conditions: welding current, arc voltage, and welding speed. The arc start control method described in (1), characterized by the above. This arc start control method allows for a stable transition to a steady-state welding period by appropriately controlling the control conditions according to the wire position phase or feed rate phase in one cycle consisting of a forward feed period and a reverse feed period.

[0137] (3) In the transition section, the control conditions that are varied in addition to the average feed rate set value are: The wire frequency when the forward and reverse transmission periods are considered as one cycle, Wire amplitude, The start timing of the conditions controlled according to the wire position phase or feed rate phase, The termination timing of the conditions controlled according to the wire position phase or feed rate phase, The set value for the welding current, and, Arc voltage setting value, At least one of the following: The arc start control method described in (2), characterized by the above. According to this arc start control method, by appropriately controlling one or more of the above-mentioned control conditions during the transition period, a stable transition to the steady-state welding period can be achieved.

[0138] (4) Conditions to be controlled according to the wire position phase or feed rate phase include at least the welding current, The welding current control is a control that switches between a suppression period and an unsuppression period of the welding current according to the wire position phase or feeding speed phase. In the transition section, the control conditions that are varied in addition to the average feed rate set value are at least the start timing of the unsuppressed welding current period and the end timing of the unsuppressed welding current period. The arc start control method described in (3), characterized by the above. This arc start control method allows for a stable transition to a steady-state welding period by appropriately controlling the switching timing between the welding current suppression period and the non-suppression period.

[0139] (5) The initial section includes a maintenance unit that maintains the average feed rate setting value at a predetermined value, In the maintenance unit, the end of the initial section is determined based on a predetermined time, or at least one of the arc voltage and arc length. An arc start control method as described in any one of (1) to (4), characterized by the above. This arc start control method allows the process to transition to control of the transition section based on the arc voltage and arc length.

[0140] (6) In the transition section, the set value of the control condition to be varied is: A predetermined periodic unit, The wire frequency unit, when the forward transmission period and the reverse transmission period are considered as one cycle, is varied according to at least one of them. An arc start control method as described in any one of (1) to (4), characterized by the above. This arc start control method allows the control conditions to be varied based on the period or frequency.

[0141] (7) Control the ratio (FW-AVE1 / FW-AVE2) between the average feed rate setting value FW-AVE1 in the initial section and the average feed rate setting value FW-AVE2 in steady-state welding to be 0.9 or less. An arc start control method as described in any one of (1) to (4), characterized by the above. According to this arc start control method, for example, the average feed rate in the initial phase can be set as a ratio based on a predetermined average feed rate for the steady-state welding period.

[0142] (8) In the transition section, The average feed rate setting value increases linearly, curvedly, or in a stepwise manner. The wire frequency varies to increase linearly, curvedly, or in a step-like manner. The wire amplitude is to vary so as to decrease linearly, curvedly, or in a step-like manner. The arc start control method described in (3), characterized by the above. This arc start control method allows various control conditions to be varied in an appropriate manner depending on the type.

[0143] (9) In the transition interval, the control conditions are varied based on a predetermined time or a predetermined slope value. An arc start control method as described in any one of (1) to (4), characterized by the above. According to this arc start control method, the rate of change of control conditions can be set based on time or slope.

[0144] (10) The start timing of the second control period is immediately after the initial droplet formed in the first control period has short-circuited, or immediately after the initial droplet has reached a desired size. An arc start control method as described in any one of (1) to (4), characterized by the above. This arc start control method allows the control mode to transition from the first control period to the second control period, triggered by the initial state of the molten droplet.

[0145] (11) The steps in the first control period from the start of welding to the generation of an arc are: After welding begins, the welding wire is fed forward at a predetermined initial feeding speed, and after determining the current flow between the welding wire and the base material, a predetermined first welding current value is maintained for a predetermined time in a first section. After the first section, there is a second section having a rise section for a predetermined time to increase the welding current to a second welding current value, and a maintenance section for maintaining the second welding current value. It has, After the second section, the welding wire is fed in reverse at a predetermined feeding speed while generating an arc. An arc start control method as described in any one of (1) to (4), characterized by the above. This arc start control method allows for appropriate control of the feed rate and welding current during the period from the start of welding to arc generation.

[0146] (12) The period in the first control period after arc generation and when initial droplets are formed is: After arc generation, there is a third section in which the welding wire feeding is stopped and a predetermined third welding current value is maintained for a predetermined time. An arc start control method as described in any one of (1) to (4), characterized by the above. This arc start control method allows for appropriate control of the feed rate and welding current during the period from arc generation to the formation of the initial droplet.

[0147] (13) An arc start control program for controlling the arc start period from the start of welding to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. For computers in systems that have at least a power supply, In the transition section, in addition to the average feed rate setting value, a function is provided to vary at least one of the control conditions related to the feed control method. The arc start control program to be executed. This arc start control program enables a stable transition to a steady-state welding period in gas-shielded arc welding or additive manufacturing utilizing gas-shielded arc welding, regardless of the welding method or deposition method.

[0148] (14) A power supply having a function to control the arc start period from the start of welding to the transition to the steady-state welding period in welding by the gas shielded arc welding method or additive manufacturing utilizing the gas shielded arc welding method, The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. The power supply, in the transition section, varies at least one of the control conditions related to the feed control method, in addition to the average feed speed set value. A power supply characterized by the following. This power supply enables a stable transition to a steady-state welding period in gas shielded arc welding or additive manufacturing utilizing the gas shielded arc welding method, regardless of the welding method or bonding method.

[0149] (15) An arc start control system for controlling the arc start period from the start of welding to the transition to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The arc start control system includes at least a power supply, The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An arc start control system characterized by the following: This arc start control system enables a stable transition to a steady-state welding period in gas-shielded arc welding or additive manufacturing utilizing the gas-shielded arc welding method, regardless of the welding method or bonding method.

[0150] (16) A welding method using the gas shielded arc welding method, A system equipped with at least a power supply controls the arc start period from the start of welding to the transition to the steady-state welding period. The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. A welding method characterized by the following. This welding method allows for a stable transition to a steady-state welding period in gas shielded arc welding, regardless of the welding method or deposition method.

[0151] (17) Additive manufacturing method utilizing gas shielded arc welding, A system equipped with at least a power supply controls the arc start period from the start of additive manufacturing to the transition to the steady welding period of additive manufacturing. The aforementioned arc start period is A first control period includes the period from the start of welding until an arc is generated, and the period after arc generation during which initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An additive manufacturing method characterized by the following. This additive manufacturing method allows for a stable transition to a steady-state welding period in additive manufacturing using gas shielded arc welding, regardless of whether the welding method or bonding method is used. [Explanation of symbols]

[0152] 1 AC power supply 2 Primary rectifier 3. Smoothing Capacitor 4 Switching elements 5 transformers 6 Secondary rectifier 7 Reactor 30 Inverter drive unit 31 Current detection unit 32 Voltage detection unit 33 Detachment detection unit 34 Current Error Amplification Section 35. Supply setting data section 36 Current setting section 36A target current setting section 36B Wire tip position conversion unit 36C Voltage setting section 37 Waveform Control Table Linear Calculation Unit 38 Phase delay correction unit 39 Push Feeder Control Unit 40 A / D Input Section 41 Electrical angle adjustment section 42 Digital Communications Department 43 Welding Sequence Section 50 Welding Systems 100 welding wires 110 Welding Robots 111 Welding Torch 120 Welding control device 122 Digital Communications Department 123 Digital Communications Department 140 Welding Power Supply 141 Control System Section 150 controllers 160 Servo Amplifier 161 Forward / reverse feed command generation unit 162 Digital Communications Department 163 Synchronization signal generation unit 170 Servo motors 180 Push Motor 190 Wire Buffer 191 Serial-to-analog conversion section 200 work

Claims

1. A method for controlling the arc start period from the start of welding to the transition to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The aforementioned arc start period is A first control period includes the period from the start of welding until the arc is generated, and the period after the arc is generated during which the initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is, The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An arc start control method characterized by the following.

2. The feeding control method during the second control period is: The forward and reverse transmission periods constitute one cycle. The conditions for control according to the wire position phase or feeding speed phase in the aforementioned one cycle are: Control at least one of the following conditions: welding current, arc voltage, and welding speed. The arc start control method according to claim 1, characterized by the above.

3. In the transition section, the control conditions that are varied in addition to the average feed rate set value are: The wire frequency when the forward and reverse transmission periods are considered as one cycle, Wire amplitude, The start timing of the conditions controlled according to the wire position phase or feed rate phase, The termination timing of the conditions controlled according to the wire position phase or feed rate phase, The set value for the welding current, and, Arc voltage setting value, At least one of the following: The arc start control method according to claim 2, characterized by the above.

4. The conditions for control according to the wire position phase or feed rate phase include at least the welding current, The welding current control is a control that switches between a suppression period and an unsuppression period of the welding current according to the wire position phase or feeding speed phase. In the transition section, the control conditions that are varied in addition to the average feed rate setting value are at least the start timing of the unsuppressed welding current period and the end timing of the unsuppressed welding current period. The arc start control method according to claim 3, characterized by the above.

5. The initial section includes a maintenance unit that maintains the average feed speed setting value at a predetermined value. In the maintenance unit, the end of the initial section is determined based on a predetermined time, or at least one of the arc voltage and arc length. An arc start control method according to any one of claims 1 to 4, characterized by the above.

6. In the transition section, the set value of the control condition to be varied is: A predetermined periodic unit, The wire frequency unit, when the forward transmission period and the reverse transmission period are considered as one cycle, is varied according to at least one of them. An arc start control method according to any one of claims 1 to 4, characterized by the above.

7. The ratio (FW-AVE1 / FW-AVE2) between the average feed rate setting value FW-AVE1 in the initial section and the average feed rate setting value FW-AVE2 in steady-state welding is controlled to be 0.9 or less. An arc start control method according to any one of claims 1 to 4, characterized by the above.

8. In the aforementioned transition section, The average feed rate setting value increases linearly, curvedly, or in a stepwise manner. The wire frequency varies to increase linearly, curvedly, or in a step-like manner. The wire amplitude is to vary so as to decrease linearly, curvedly, or in a step-like manner. The arc start control method according to claim 3, characterized by the above.

9. In the transition interval, the control conditions are varied based on a predetermined time or a predetermined slope value. An arc start control method according to any one of claims 1 to 4, characterized by the above.

10. The start timing of the second control period is either immediately after the initial droplet formed in the first control period has short-circuited, or immediately after the initial droplet has reached a desired size. An arc start control method according to any one of claims 1 to 4, characterized by the above.

11. The steps in the first control period, from the start of welding to the generation of an arc, are: After welding begins, the welding wire is fed forward at a predetermined initial feeding speed, and after determining the current flow between the welding wire and the base material, a predetermined first welding current value is maintained for a predetermined time in a first section. After the first section, there is a second section having a rise section for a predetermined time to increase the welding current to a second welding current value, and a maintenance section for maintaining the second welding current value. It has, After the second section, the welding wire is fed in reverse at a predetermined feeding speed while generating an arc. An arc start control method according to any one of claims 1 to 4, characterized by the above.

12. During the first control period, the period after arc generation and when initial droplets are formed is: After arc generation, there is a third section in which the welding wire is stopped and a predetermined third welding current value is maintained for a predetermined time. An arc start control method according to any one of claims 1 to 4, characterized by the above.

13. An arc start control program for controlling the arc start period from the start of welding to the transition to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The aforementioned arc start period is A first control period includes the period from the start of welding until the arc is generated, and the period after the arc is generated during which the initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is, The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. For computers in systems that have at least a power supply, In the transition section, in addition to the average feed rate setting value, a function is provided to vary at least one of the control conditions related to the feed control method. The arc start control program to be executed.

14. A power supply having a function to control the arc start period from the start of welding to the transition to the steady-state welding period in welding by the gas shielded arc welding method or additive manufacturing utilizing the gas shielded arc welding method, The aforementioned arc start period is A first control period includes the period from the start of welding until the arc is generated, and the period after the arc is generated during which the initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is, The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. The power supply, in the transition section, varies at least one of the control conditions related to the feed control method, in addition to the average feed speed set value. A power supply characterized by the following.

15. An arc start control system for controlling the arc start period from the start of welding to the transition to the steady-state welding period in welding by gas shielded arc welding or additive manufacturing utilizing gas shielded arc welding, The arc start control system includes at least a power supply, The aforementioned arc start period is A first control period includes the period from the start of welding until the arc is generated, and the period after the arc is generated during which the initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is, The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An arc start control system characterized by the following:

16. A welding method using the gas shielded arc welding method, A system equipped with at least a power supply controls the arc start period from the start of welding to the transition to the steady-state welding period. The aforementioned arc start period is A first control period includes the period from the start of welding until the arc is generated, and the period after the arc is generated during which the initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is, The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. A welding method characterized by the following.

17. An additive manufacturing method utilizing gas shielded arc welding, A system equipped with at least a power supply controls the arc start period from the start of additive manufacturing to the transition to the steady welding period of additive manufacturing. The aforementioned arc start period is A first control period includes the period from the start of welding until the arc is generated, and the period after the arc is generated during which the initial droplets are formed. The system includes at least the period after the initial droplet formation period, followed by a second control period from the time of switching to a feed control method that alternately switches the feed rate between a forward feed period and a reverse feed period until the system transitions to the steady-state welding period using the feed control method, The second control period is, The second control period includes an initial phase in which the feed rate is maintained for an arbitrary time at an average feed rate lower than the steady-state welding feed rate or the average feed rate setting value, and a transition phase in which the feed rate transitions from the average feed rate at the end of the initial phase to the steady-state welding feed rate or the average feed rate setting value. In the transition section, in addition to the average feed rate setting value, at least one of the control conditions related to the feed control method is varied. An additive manufacturing method characterized by the following.

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