Arc end control method, welding power supply, welding system, and program

Abstract

To enable stable arc end control regardless of the welding method. [Solution] In the arc end control method, the ball removal control period during the anti-stick period starts immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. Immediately after the welding start signal is switched to OFF, step S1 is performed to change from a first wire feed speed setting value Fs, which is the wire feed speed setting value for the actual welding, to an arbitrary second wire feed speed setting value Fsa. From the start of the ball removal control period, a current non-suppression period T is performed for the welding current. IP and current suppression period T IB The process is repeated in step S2, and during the ball removal control period, at least one of droplet detachment detection monitoring and short circuit detection monitoring is performed, followed by a current suppression period T. IB The device includes step S3, which reduces the feeding speed when either droplet detachment or a short circuit is detected.

Description

[Technical Field]

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

[0002] Gas shielded arc welding uses various welding methods depending on the application, such as short-circuit welding, pulse welding, and feed-controlled welding. However, regardless of the method, even if a wire feed stop signal is issued at the end of welding (short-circuit welding, pulse welding, or feed-controlled welding), the wire continues to feed due to the motor's inertia, plunges into the molten pool, causing the workpiece and wire to adhere, or distorting the wire tip shape after solidification, affecting the arc start performance of the next weld. Therefore, arc end control is implemented to supply an appropriate output for a short time, allowing the wire fed by the motor's inertia to melt (hereinafter also referred to as the "anti-stick period"). This prevents the workpiece and wire from adhering at the end of welding and improves the arc start performance of the next weld.

[0003] Patent Document 1 discloses an arc welding control method in which, in welding where the feeding speed is alternately switched between a forward feeding period and a reverse feeding period, the welding state during the anti-stick period at the end of welding is stabilized by performing forward and reverse feeding control, which alternately switches the feeding speed Fw of the welding wire between a forward feeding period and a reverse feeding period, thereby generating a short-circuit period and an arc period for welding. In this method, at the time t13 when a welding end command is input and the transition from the arc period to the short-circuit period is made, the feeding speed Fw is switched from forward and reverse feeding control to forward feeding control to end the welding. As a result, during the anti-stick period after the switch to forward feeding control, the welding wire is controlled to feed in the forward direction, thus achieving a stable welding state.

[0004] Furthermore, Patent Document 2 discloses a technology in which, when a welding termination signal is input during arc welding, the welding wire is accelerated to cause a short circuit between the welding wire and the base material, and then the welding wire is reversed. When a predetermined wire reverse feeding speed is reached, the wire feeding speed is controlled to a constant predetermined wire reverse feeding speed and the wire is reversed for a predetermined time before the feeding of the welding wire is stopped. A constant predetermined welding current is output for a predetermined welding time, starting from the time when the short circuit that occurs during the reverse feeding of the welding wire is opened, and then the welding output is stopped. This makes it possible to control the shape of the wire tip to a uniform size without variation at the end of welding, and to suppress the effect of slag at the next arc start and achieve a good arc start.

[0005] Furthermore, Patent Document 3 discloses an arc welding control method in which welding is performed by generating a short-circuit period and an arc period by alternately switching the welding wire feeding speed Fw between a forward feeding period and a reverse feeding period, and at the time t14 when a welding termination command is input and the transition from the short-circuit period to the arc period is made, the feeding speed Fw is switched from forward-reverse feeding control to reverse feeding control to terminate welding. As a result, during the anti-stick period after switching to reverse feeding control, the welding wire is controlled to feed in the reverse direction, so the arc state continues, and a stable welding state is disclosed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-150350 [Patent Document 2] International Publication No. 2011 / 024380 [Patent Document 3] International Publication No. 2016 / 117228 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Incidentally, during the anti-sticking period, on the premise of preventing adhesion between the workpiece and the wire at the end of welding, it is required to stabilize the arc during the anti-sticking period and improve the arc starting performance at the next welding. In particular, in improving the arc starting performance at the next welding, in order to stabilize the shape of the wire tip at the end of welding, it is ideal to control the shape of the wire tip to be spherical or as pointed as possible (hereinafter also referred to as "ball-forming control").

[0008] When the solidified wire tip at the end of welding becomes as pointed as possible, the arc stability at the next welding becomes is more becomes more favorable. However, when slag adheres to the wire tip, arc starting may not be possible. In this case, by further processing after the ball-forming control, the wire tip can be made into an arbitrary size or shape more easily, without being affected by the slag adhering to the wire tip, and the arc stability at the next welding may become more favorable. However, for Patent Documents 1 and 3, no consideration is given to the ball-forming control. Further, for Patent Document 2, although controlling the shape of the wire tip is described, no consideration is given to the ball-forming control, and no consideration is given to stabilizing the arc during the anti-sticking period. Further, what is done in Patent Documents 1 and 3 is control of the anti-sticking period dedicated to feed control welding, and it is not general-purpose.

[0009] The present invention has been made in view of the above-described problems, and an object thereof is to provide an arc end control method, a welding power source, a welding system, and a program for performing stable arc end control regardless of the welding method.

Means for Solving the Problems

[0010] The present invention has the following configuration.

[0011] (1) An arc end control method in an arc end control period provided immediately after a welding start signal is switched to OFF in arc welding, The arc end control period includes at least an anti-sticking period. The anti-sticking period includes at least a ball removal control period for removing the droplet at the tip of the welding wire. The ball removal control period starts immediately after the welding start signal is switched to OFF or after a certain period from when the welding start signal is switched to OFF. Step S1 of changing from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value during this welding, to an arbitrary second wire feeding speed setting value Fsa immediately after the welding start signal is switched to OFF. From the start of the ball removal control period, a current non-suppression period T IP and a current suppression period T IB are repeated in step S2. During the ball removal control period, at least one of droplet detachment detection monitoring and short-circuit detection monitoring is performed. When either droplet detachment or a short circuit is detected during the current suppression period T IB step S3 of reducing the feeding speed is included. The arc end control method is characterized by this.

[0012] (2) A welding power source that performs arc end control in an arc end control period provided immediately after the welding start signal is switched to OFF in arc welding, The arc end control period includes at least an anti-sticking period. The anti-sticking period includes at least a ball removal control period for removing the droplet at the tip of the welding wire. The ball removal control period starts immediately after the welding start signal is switched to OFF or after a certain period from when the welding start signal is switched to OFF. Immediately after the welding start signal is switched to OFF, the feeding speed of the welding wire is changed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value during this welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball removal control period, a current non-suppression period T IP and a current suppression period T IB are repeated. During the bead-taking control period, at least one of droplet detachment detection monitoring and short-circuit detection monitoring is performed, and when either droplet detachment or a short circuit is detected during the current suppression period T IB of the welding wire, the feeding speed of the welding wire is reduced. A welding power source characterized by this.

[0013] (3) A welding system that performs arc end control during an arc end control period provided immediately after the welding start signal is switched off in arc welding, where the arc end control period includes at least an anti-sticking period, the anti-sticking period includes at least a bead-taking control period for removing the droplet at the tip of the welding wire, the bead-taking control period starts immediately after the welding start signal is switched off or after a certain period from when the welding start signal is switched off, immediately after the welding start signal is switched off, the feeding speed of the welding wire is changed from the first wire feeding speed setting value Fs, which is the wire feeding speed setting value during this welding, to an arbitrary second wire feeding speed setting value Fsa, from the start of the bead-taking control period, for the welding current, a current non-suppression period T IP and a current suppression period T IB are repeated, during the bead-taking control period, at least one of droplet detachment detection monitoring and short-circuit detection monitoring is performed, and when either droplet detachment or a short circuit is detected during the current suppression period T IB of the welding wire, the feeding speed of the welding wire is reduced. A welding system characterized by this.

[0014] (4) A program that performs arc end control during an arc end control period provided immediately after the welding start signal is switched off in arc welding, where the arc end control period includes at least an anti-sticking period, the anti-sticking period includes at least a bead-taking control period for removing the droplet at the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. A welding system equipped with at least a welding power source, Immediately after the welding start signal is switched OFF, the welding wire feeding speed is changed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value during actual welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. IP and current suppression period T IB A function that repeats, During the aforementioned droplet removal control period, at least one of the following is performed: droplet detachment detection monitoring and short-circuit detection monitoring, and the current suppression period T IB A program characterized by having a function that reduces the feeding speed of the welding wire when either droplet separation or a short circuit is detected. [Effects of the Invention]

[0015] According to the present invention, in gas shielded arc welding, regardless of the welding method, it is possible to maintain excellent arc stability during the anti-stick period and to create a welding wire tip shape that provides excellent arc stability during subsequent welding. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of the welding system according to this embodiment. [Figure 2] Figure 2 is a block diagram showing the schematic configuration related to the control of the welding power supply, robot control device, and servo amplifier in this embodiment. [Figure 3] Figure 3 is a graph illustrating the relationship between the wire feeding speed, wire tip position, and current detection signal during the main welding process and the ball-catching control period described later in this embodiment. [Figure 4] Figure 4 is a timing chart corresponding to this embodiment. [Figure 5]Figure 5 is an enlarged view of a portion of the timing chart shown in Figure 4. [Modes for carrying out the invention]

[0017] Hereinafter, embodiments of the arc end control method, welding power supply, welding system, and program according to the present invention will be described in detail with reference to the drawings.

[0018] This embodiment is an example of a case using a welding robot, and the arc end control method, welding power supply, welding system, and program 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 used instead of the welding robot body, or a portable small welding robot may be used. Furthermore, in this embodiment, the case of the feed control method, that is, the main welding period before entering the end processing period, is an example of welding performed using the feed control method, but the present invention may also be applied to pulsed MAG welding, carbon dioxide welding, etc.

[0019] 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 robot 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.

[0020] The welding power supply 140 is connected to the welding robot 110 via a positive power cable 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. 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.

[0021] 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.

[0022] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a current supply mechanism, i.e., a contact tip, for supplying current to the welding wire 100. The welding wire 100 generates an arc from its tip when current is supplied from the contact tip, and uses the heat from this arc to weld the workpiece 200, which is the target of welding.

[0023] 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 from the viewpoint of versatility, it is preferable that it contains at least one gas with a high potential gradient, such as carbon dioxide, nitrogen, hydrogen, or oxygen. 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, and a system in which 90% by volume of carbon dioxide is mixed is even more preferable. Carbon dioxide alone may also be used. The shielding gas is supplied from a shielding gas supply device (not shown).

[0024] 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.

[0025] 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 easily 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.

[0026] 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, it is preferable to set the upper limit of the diameter to 1.6 mm and the lower limit to 0.8 mm.

[0027] 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 robot control device 120 mainly controls the operation of the welding robot 110. Therefore, the robot control device 120 may be referred to as a robot controller. The robot 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. The robot control device 120 also provides welding conditions such as welding current, welding voltage, and feed speed to the welding power supply 140 during the welding operation according to the teaching data.

[0028] As shown in Figure 1, the welding system 50 of this embodiment has a robot control device 120 that is independent of the welding power supply 140, but it is also possible to have a configuration in which the robot control device 120 is included in the welding power supply 140.

[0029] The controller 150 is connected to the robot 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 robot 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 robot control device 120 can be wired or wireless, and there is no particular limitation on the type of connection.

[0030] The welding power supply 140, in response to a command from the robot 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 robot control device 120.

[0031] 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 illustrating the schematic configuration related to the control of the welding power supply 140, robot 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 during the welding process and the ball-catching control period described later in this embodiment.

[0032] The welding power supply 140 is connected to the robot control device 120 via digital communication, and the robot control device 120 is connected to the servo amplifier 160 via digital communication. In other words, the servo amplifier 160, robot 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 robot 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.

[0033] In this embodiment, communication between the welding power supply 140 and the robot control device 120 is via CAN (Controller Area Network), which is one of the industrial field networks, and communication between the robot control device 120 and the servo amplifier 160 is via EtherCAT (Ethernet for Control Automation Technology) (registered trademark), which is one of the industrial field networks, but the embodiment is not limited to these.

[0034] (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 robot 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 time and end time for each of the peak period Dap, fall period Ddwn, base period Db, and rise period Dup related to current control. The wire tip position conversion unit 36B has the function of obtaining information on the tip position of the welding wire 100.

[0035] 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, and databases may be stored in any of the components of the welding system 50. For example, the settings, tables, and databases may be stored in the robot control device 120 or the welding power supply 140. These settings, tables, and databases may be stored in the waveform control table linear calculation unit 37, and the setting values ​​to be used are selected for each status of the welding sequence unit 43: arc start, welding in progress, and anti-stick.

[0036] Current non-suppression period T IP (In this embodiment, the sum of the Dup and Dap periods), current suppression period T IB The various conditions for the peak period Dap, falling period Ddwn, base period Db, and rising period Dup (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 refer to the setting of conditions such as current value, time, or phase.

[0037] The welding current is determined based on the phase related to the wire tip position (hereinafter referred to as "wire position phase" or "position phase") during the current non-suppression period T. IP and current suppression period T IB This shows a pulse waveform in which the welding current alternates. In this embodiment, the timing of the peak period Dap, fall period Ddwn, base period Db, and rise period Dup is controlled based on the wire position phase from 0 to 360° (0 to 2π), where 0° is when the wire tip is closest to the tip side and 180° is when it is closest to the base material side.

[0038] Based on the setting value of the average feed rate Favg in the welding condition information stored by the control system unit 141, the current non-suppression period T is calculated by the waveform control table linear calculation unit 37. IP The set current value Iap for the peak period Dap (hereinafter also referred to as "peak current Iap") and the current suppression period T IB The set current value Ib for the base period Db (hereinafter also referred to as "base current Ib") is set in the current setting unit 36.

[0039] In this embodiment, the welding current is basically controlled by two values: the peak current Iap and the base current Ib. Therefore, the current suppression period T IB The start time of the current suppression period T may be expressed as the base current start time, which is the time it takes to transition to the base current Ib, i.e., the start time of the falling edge period Ddwn. IBThe time when this process ends may also be expressed as the time when the base current Ib ends, i.e., the base current termination time. This current suppression period T IB The start time and current suppression period T IB The duration (hours) of the falling edge period Ddwn and the duration (hours) of the base period Db, which relate to the time when the current ends, are calculated by the waveform control table linear calculation unit 37. Current non-suppression period T IP The time when this begins, i.e., the start time of the rise period Dup, may also be expressed as the peak current start time, and the current non-suppression period T IP The time at which the peak current 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 determined by a set period d1, starting with a wire position phase of 0°, and the timing of the peak current start time is determined by a set period d2, starting with the peak current end time. This set period is often set in terms of phase. For example, if d1 is set to 160° and d2 to 205°, the peak current will end at a wire position phase of 160° (d1) and start at a wire position phase of 365° (d1+d2).

[0040] 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.

[0041] 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.

[0042] 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, which includes periodic setting information and the difference between the operating signal of the actual forward and reverse feeding operation 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.

[0043] 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.

[0044] 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 contact tip as the output from the main power supply circuit and energizes the welding wire 100, which is a consumable electrode.

[0045] 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 wire tip 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] The current setting unit 36 ​​receives a voltage setting signal Vap, which is the target value of the voltage applied between the welding tip and the base material 200, from the voltage setting unit 36C.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The waveform control table linear calculation unit 37 is given the average feeding speed Favg of the weld wire 100 being fed. The average feeding speed Favg is stored in advance in the feeding setting data unit 35. In this embodiment, the feeding setting data unit 35 is located in the welding power supply 140, but various information related to the feeding setting may be stored in the robot control device 120, and this information may be output from the robot control device 120 to the welding power supply 140.

[0056] 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.

[0057] 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 use that set value instead of the average feed rate Favg. 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 used instead of the average feed rate Favg.

[0058] The feed setting data unit 35 may store setting values ​​such as the average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Hf, and wire forward / reverse period Tf. The wire amplitude Wf, wire forward / reverse frequency Hf, 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.

[0059] 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 feeding in which the positive and negative feeding periods alternate (hereinafter abbreviated as "amplitude feeding"). Note that 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., the speed 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 the wire amplitude, which is the repeating unit. The wire forward / reverse frequency Hf is the reciprocal of the wire forward / reverse period Tf.

[0060] The average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Hf, 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 robot control device 120. In this embodiment, this feed setting data is communicated via CAN communication.

[0061] 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, the welding condition information held by the robot control device 120 is shown enclosed in a dashed line within the welding power supply 140 for convenience.

[0062] (Functional configuration of robot control device) As described above, the digital communication unit 122 of the robot control device 120 receives feed setting data such as the average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Hf, and wire forward / reverse period Tf from the feed setting data unit 35 of the welding power supply 140 via CAN communication. The robot 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 robot control device 120 and the digital communication unit 162 of the servo amplifier 160 are connected by EtherCAT® communication.

[0063] (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 Hf, 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.

[0064] In this embodiment, the feed rate command signal Fw is expressed by the following equation. Fw=Ff+Favg...Formula (A)

[0065] 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.

[0066] 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.

[0067] 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 Hf, 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.

[0068] Here, the phase related to the wire feed speed command signal Fw (hereinafter also referred to as the "feed speed phase") is set as follows: 0° for the start of forward feeding, 180° (π) for the end of forward feeding and the start of reverse feeding, and 360° (2π) for the end of reverse feeding. In this embodiment, if the value of the wire feed speed Fw is less than the average feed speed Favg, it means reverse feeding; if the value is equal to or greater than the average feed speed Favg, it means forward feeding. In this embodiment, the phase synchronization signal consists of a synchronization signal for the feed speed phase and a synchronization signal for the wire position phase. The synchronization signal for the feed speed phase 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 set to 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 and backward (position 0.5π to 1.5π), and to OFF during the period when the wire is closer to the tip side than the center position of the wire amplitude (position 1.5π to 0.5π). Based on this phase synchronization signal and the aforementioned phase delay correction amount, the tip position of the welding wire 100, i.e., the wire position phase, is determined by the wire tip position conversion unit (deg) 36B in the welding power supply 140.

[0069] <Arc End Control> Next, the arc end control according to the present invention will be described with reference to Figure 4. Figure 4 is a timing chart corresponding to this embodiment. In this embodiment, the arc end control is the period from immediately after the welding start signal is switched to OFF until the control is completely stopped, and includes the anti-stick period. In this embodiment, as will be described later, the arc end control consists of the status of a de-adhesion processing period (not shown) and an after-flow period in the welding sequence section 43 of Figure 2 after the anti-stick period, but is not limited to this.

[0070] In the welding sequence unit 43, when the welding start signal is turned ON, the status changes to "welding in progress," and when the welding start signal is turned OFF, the "welding in progress" status ends and arc end control begins. In this embodiment, as shown in Figure 4, at least an anti-stick period, a de-adhesion processing period, and an after-flow processing period are included, and arc end control ends with the end of the after-flow processing period. In this embodiment, the anti-stick period consists of a "ball-taking control period" that controls the wire tip shape to be as pointed as possible, and a "ball-forming control period" that changes the wire tip from a pointed shape to an arbitrary size or shape. However, it is not limited to this, and if a ball-taking control period is provided, good arc stability can be obtained during the anti-stick period, and the arc start performance for the next welding will be good. Therefore, the anti-stick period may consist only of the ball-taking control period, or other controls may be included in addition to the ball-taking control period. For example, as in this embodiment, if the wire tip is made pointed during the ball-taking control period, the size or shape of the wire tip after solidification can be controlled more easily and accurately during the subsequent ball-forming control period, resulting in better arc start performance for the next weld. In other words, if a ball-forming control period is provided without the ball-taking control period according to the present invention, variations will occur in the wire tip shape before the ball-forming control period, resulting in poor accuracy of the size or shape of the wire tip after solidification.

[0071] Figure 4 is a timing chart corresponding to this embodiment, showing the welding start signal, wire feed speed setting value Fset (= average feed speed Favg), welding current, and timing for each control period. Furthermore, Ta is the point when the welding start signal turns OFF and arc end control begins, Tb is the point when the anti-stick period begins (start of ball removal control period), Tc is the point when the ball removal control period ends (start of ball formation control period), Td is the point when the anti-stick period ends (end of ball formation control period, start of de-adhesion processing period), Te is the point when the de-adhesion processing period ends (start of afterflow), and Tf is the point when arc end control ends (end of afterflow).

[0072] (Ta~Tb period) When the main welding is completed, i.e., the welding start signal is turned OFF, arc end control begins. At the time when arc end control begins (Ta), the wire feed speed set value Fset (= average feed speed Favg) is changed from the first wire feed speed set value Fs, which is the wire feed speed set value during the main welding, to an arbitrary second wire feed speed set value Fsa, and forward and reverse feeding is performed. In Figure 4, the maximum wire feed speed at the start of anti-sticking corresponds to the second wire feed speed set value Fsa. In this embodiment, the wire feed speed set value for the main welding is controlled to decrease and maintained until the anti-sticking period begins. Other conditions besides the wire feed speed set value can be determined based on the parameter table during the main welding and the changed second wire feed speed set value Fsa. The period from Ta to Tb is a transition period for changing from the first wire feed speed set value Fs to an arbitrary second wire feed speed set value Fsa. In other words, if this transition period is instantaneous, Ta and Tb can be considered to occur at approximately the same time.

[0073] (Tb~Tc period) The anti-stick period begins, and the ball-retrieval control period begins simultaneously. In this embodiment, the ball-retrieval control period begins at the same time as the anti-stick period, but this is not limited to this; some form of control may be included before the ball-retrieval control period. When the ball-retrieval control period begins, if the welding method is feed control, the parameter table is applied as is; if the welding method is other than feed control, the parameter table for the anti-stick period is switched, and various conditions are determined based on the second wire feed speed setting value Fsa. Even during the ball-retrieval control period, as described above, the welding current is controlled by switching between peak current and base current depending on the wire position. Current non-suppression period T IP and current suppression period T IB The start timing is determined by the position of the welding wire tip.

[0074] During the ball-catching control period, the welding wire may be fed at a second wire feeding speed setting value Fsa, which is an arbitrary average wire feeding speed, while alternately feeding in the forward and reverse directions.

[0075] Furthermore, a waveform table defining the pulse waveform of the welding current may be provided in advance. If the second wire feeding speed setting value Fsa is equal to or greater than the first wire feeding speed setting value Fs, the pulse waveform during the ball-catching control period may be determined using the same waveform table as during the actual welding. If the second wire feeding speed setting value Fsa is lower than the first wire feeding speed setting value Fs, the conditions for the pulse waveform during the ball-catching control period may be determined using a different waveform table than that used during the actual welding.

[0076] Here, please also refer to Figure 5. Figure 5 is an enlarged view of a portion of the timing chart shown in Figure 4. As shown in Figure 5, the welding current is set for the base period and the first base period D b1 and the second base period D b2 It is preferable to control the welding current in separate phases. By performing such control, arc stability during the anti-stick period is further improved, and the generation of spatter and other issues is effectively suppressed.

[0077] Furthermore, in this invention, at least one of either droplet detachment detection monitoring or short-circuit detection monitoring is performed. The end time Tc of the droplet removal control period is the current suppression period T IB In this case, the end time Tc is the point at which either droplet detachment or a short circuit is detected. By determining the end time Tc of the droplet removal control period in this way, the wire tip shape will be reliably sharp. In other words, droplet removal will be reliably successful. In this embodiment, both droplet detachment detection monitoring and short circuit detection monitoring are performed, and the point at which either is detected first is set as the end time Tc of the droplet removal control period. It is preferable that the droplet detachment detection monitoring and short circuit detection monitoring be started after a certain amount of time has elapsed since the start of the droplet removal control period, or after a predetermined number of welding current pulses have been output since the start of the droplet removal control period. The number of pulse outputs refers to the number of times welding current pulses have been output from a predetermined reference time. In this example, the predetermined reference time is the time when the droplet removal control period begins. By starting each detection means in this way, it is possible to suppress droplet removal failures due to false detections. In this embodiment, each detection means is started after one welding current pulse has been output. In this way, by timing the activation of each detection means to occur after outputting one pulse of welding current, the end shape of the weld bead is improved.

[0078] Furthermore, each detection means may be given a time limit. For example, if detachment or short circuit detection has not occurred after a certain amount of time has elapsed or a predetermined number of pulse outputs have elapsed since the start of the ball retrieval control period, the ball retrieval control period may be forcibly terminated. A certain amount of time elapsed is, for example, after Tb time has elapsed. In other words, if detachment or short circuit detection is not occurred during the ball retrieval control period, the feed rate may be reduced if at least one of the following conditions is met: a certain amount of time has elapsed since the start of the ball retrieval control period, or a predetermined number of welding current pulses have been output since the start of the ball retrieval control period.

[0079] If the Tc~Td period (ball-forming control period) described later is not provided, after reducing the feed rate, the welding current may be reduced to 0 or near 0 to end the anti-stick period.

[0080] (Tc~Td period) At the end of the ball-catching control period, the wire feed speed setting may be reduced or set to 0 to end the anti-stick period; however, in this embodiment, the ball-forming control period is started. During the ball-forming control period, an arbitrary current is maintained for a predetermined time. This controls the size or shape of the wire tip after solidification. Then, the ball-forming control period ends (Td) after a predetermined time has elapsed. That is, during the ball-forming control period, after the ball-catching control period ends, the feed speed is reduced, the welding current is set to an arbitrary current value, and after an arbitrary time has elapsed, the welding current is reduced to 0 or near 0 to end the anti-stick period.

[0081] (Td~Te period) In this embodiment, after the ball-forming control period ends (Td), the welding current is set to 0A (amperes), and the de-welding process period begins. Setting the welding current to 0A means turning the inverter OFF. During the de-welding process period, the set current is set to several amperes (for example, 1 to 5A), and the inverter is repeatedly turned ON and OFF until the short-circuit detection switches to arc detection.

[0082] (Te~Tf period) After the inverter stops (at point Te), an after-flow period is established during which the gas flow continues for a predetermined time. Here, gas flow refers to the flow of shielding gas. When the predetermined time is reached (at point Tf), the arc end control is terminated.

[0083] (Setting value for arc voltage) The arc voltage setting can be the same during the main welding process, the anti-sticking period, and the de-adhesion treatment period. By setting it in this way, more stable arc end control can be achieved.

[0084] 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 those skilled in the art to modify and apply the various configurations of the embodiments, as well as to modify and apply them based on the description in the specification and well-known art.

[0085] As described above, the following matters are disclosed in this specification:

[0086] (1) An arc end control method during the arc end control period provided immediately after the welding start signal is switched to OFF in arc welding, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. Immediately after the welding start signal is switched to OFF, step S1 is performed to change the wire feeding speed setting value Fs, which is the wire feeding speed setting value for actual welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. IP and current suppression period T IB Step S2 is repeated, During the aforementioned droplet removal control period, at least one of the following is performed: droplet detachment detection monitoring and short-circuit detection monitoring, and the current suppression period T IB An arc end control method characterized by having step S3, which reduces the feeding speed when either droplet detachment or a short circuit is detected in the device.

[0087] (2) The arc end control method according to (1), characterized in that in step S3 of reducing the feeding speed, the feeding speed is reduced until it is stopped.

[0088] (3) During at least the ball-catching control period, the welding wire is fed at the second wire feeding speed setting value Fsa, which is an arbitrary average wire feeding speed, while alternately feeding forward and feeding backward. In step S2, the current non-suppression period T IP and the current suppression period T IB The arc end control method according to (1), characterized in that the start timing is determined according to the tip position of the welding wire.

[0089] (4) The arc end control method according to (1), characterized in that the droplet separation detection monitoring and short-circuit detection monitoring are started after a certain period of time has elapsed since the start of the droplet removal control period, or after a predetermined number of pulse outputs of welding current have been output since the start of the droplet removal control period.

[0090] (5) If, during the ball removal control period, the detection of droplet detachment or the detection of a short circuit, The arc end control method according to (1), further comprising step S4, which reduces the feed rate when at least one of the following conditions is met: a certain amount of time has elapsed since the start of the ball-catching control period, or a predetermined number of pulse outputs of welding current have been output since the start of the ball-catching control period.

[0091] (6) A waveform table that defines the pulse waveform of the welding current is provided in advance, If the second wire feeding speed setting value Fsa is greater than or equal to the first wire feeding speed setting value Fs, the pulse waveform during the ball-catching control period is determined using the same waveform table as during the actual welding. The arc end control method according to (1), characterized in that, when the second wire feeding speed setting value Fsa is lower than the first wire feeding speed setting value Fs, the conditions of the pulse waveform during the ball-catching control period are determined using a waveform table different from that used during actual welding.

[0092] (7) The arc end control method according to (1), wherein the arc end control period includes at least one of the de-welding treatment period and the after-flow period, and at least one of the de-welding treatment period and the after-flow period is provided after the end of the anti-stick period.

[0093] (8) The arc end control method according to (7), characterized in that the arc voltage setting value is the same setting value during the main welding, the anti-sticking period, and the de-adhesion treatment period.

[0094] (9) After reducing the feeding speed in step S3, The arc end control method according to any one of (1) to (8), further comprising step S5 of reducing the welding current to 0 or near 0 to terminate the antistick period.

[0095] (10) The anti-stick period includes the ball-making control period, The arc end control method according to any one of (1) to (8), characterized in that the ball-making control period further comprises step S6, after the ball-removal control period is completed in step S3, the feed rate is reduced, the welding current is set to an arbitrary current value, and after an arbitrary time has elapsed, the welding current is reduced to 0 or near 0 to end the anti-stick period.

[0096] (11) A welding power supply that performs arc end control during an arc end control period provided immediately after the welding start signal is switched OFF in arc welding, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. Immediately after the welding start signal is switched to OFF, the welding wire feeding speed is changed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value for this welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. IP and current suppression period T IB Repeat this process, During the aforementioned droplet removal control period, at least one of the following is performed: droplet detachment detection monitoring and short-circuit detection monitoring, and the current suppression period T IB A welding power supply characterized by reducing the feeding speed of the welding wire when either droplet separation or a short circuit is detected.

[0097] (12) A welding system that performs arc end control during an arc end control period provided immediately after the welding start signal is switched to OFF in arc welding, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. Immediately after the welding start signal is switched to OFF, the welding wire feeding speed is changed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value for this welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. IP and current suppression period T IB Repeat this process, During the aforementioned droplet removal control period, at least one of the following is performed: droplet detachment detection monitoring and short-circuit detection monitoring, and the current suppression period T IB A welding system characterized by reducing the feeding speed of the welding wire when either droplet detachment or a short circuit is detected.

[0098] (13) A program for performing arc end control during an arc end control period provided immediately after the welding start signal is switched to OFF in arc welding, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. A welding system equipped with at least a welding power source, Immediately after the welding start signal is switched OFF, the welding wire feeding speed is changed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value during actual welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. IP and current suppression period T IB A function that repeats, During the aforementioned droplet removal control period, at least one of the following is performed: droplet detachment detection monitoring and short-circuit detection monitoring, and the current suppression period T IB A program characterized by having a function that reduces the feeding speed of the welding wire when either droplet separation or a short circuit is detected. [Explanation of Symbols]

[0099] 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 Robot control devices 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. An arc end control method for an arc welding process that is provided immediately after the welding start signal is switched to OFF, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. Immediately after the welding start signal is switched OFF, step S1 is performed to change the wire feeding speed setting value from the first wire feeding speed setting value Fs, which is the wire feeding speed setting value for the actual welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. ＩＰ and current suppression period T ＩＢ Step S2 is repeated, During the ball removal control period, at least one of droplet detachment detection monitoring and short-circuit detection monitoring is performed, and the current suppression period T ＩＢ An arc end control method characterized by having step S3, which reduces the feeding speed when either droplet detachment or a short circuit is detected in the device.

2. The arc end control method according to claim 1, characterized in that in step S3 of reducing the feeding speed, the feeding speed is reduced until it is stopped.

3. During at least the ball-catching control period, the welding wire is fed at a second wire feeding speed setting value Fsa, which is an arbitrary average wire feeding speed, while alternately feeding forward and feeding backward. In step S2, the current non-suppression period T ＩＰ and the current suppression period T ＩＢ The arc end control method according to claim 1, characterized in that the start timing is determined according to the tip position of the welding wire.

4. The arc end control method according to claim 1, characterized in that the droplet separation detection monitoring and short-circuit detection monitoring are started after a certain period of time has elapsed since the start of the droplet removal control period, or after a predetermined number of pulse outputs of welding current have been output since the start of the droplet removal control period.

5. If, during the ball removal control period, neither the detection of droplet detachment nor the detection of a short circuit occurs, The arc end control method according to claim 1, further comprising step S4, which reduces the feed rate when at least one of the following conditions is met: a certain amount of time has elapsed since the start of the ball-catching control period, or a predetermined number of pulse outputs of welding current have been output since the start of the ball-catching control period.

6. A waveform table that defines the pulse waveform of the welding current is prepared in advance. If the second wire feeding speed setting value Fsa is greater than or equal to the first wire feeding speed setting value Fs, the pulse waveform during the ball-catching control period is determined using the same waveform table as during the actual welding. The arc end control method according to claim 1, characterized in that, when the second wire feeding speed setting value Fsa is lower than the first wire feeding speed setting value Fs, the conditions of the pulse waveform during the ball-catching control period are determined using a waveform table different from that used during actual welding.

7. The arc end control method according to claim 1, wherein the arc end control period includes at least one of the de-welding treatment period and the after-flow period, and at least one of the de-welding treatment period and the after-flow period is provided after the end of the anti-stick period.

8. The arc end control method according to claim 7, characterized in that the arc voltage setting value is the same during the main welding, the anti-sticking period, and the de-adhesion treatment period.

9. After reducing the feeding speed in step S3, The arc end control method according to any one of claims 1 to 8, further comprising step S5 of reducing the welding current to 0 or near 0 to terminate the antistick period.

10. The aforementioned anti-stick period includes the ball-making control period, The arc end control method according to any one of claims 1 to 8, characterized in that the ball-making control period further comprises step S6, after the ball-removal control period is completed in step S3, the feed rate is reduced, the welding current is set to an arbitrary current value, and after an arbitrary time has elapsed, the welding current is reduced to 0 or near 0, and the anti-stick period is completed.

11. A welding power supply that performs arc end control during the arc end control period, which is provided immediately after the welding start signal is switched OFF in arc welding, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. Immediately after the welding start signal is switched OFF, the welding wire feeding speed is changed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value for this welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. ＩＰ and current suppression period T ＩＢ Repeat this process, During the ball removal control period, at least one of droplet detachment detection monitoring and short-circuit detection monitoring is performed, and the current suppression period T ＩＢ A welding power supply characterized by reducing the feeding speed of the welding wire when either droplet separation or a short circuit is detected.

12. A welding system that performs arc end control during an arc end control period provided immediately after the welding start signal is switched OFF in arc welding, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. Immediately after the welding start signal is switched OFF, the welding wire feeding speed is changed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value for this welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-taking control period, for the welding current, a current non-suppression period T ＩＰ and a current suppression period T ＩＢ are repeated, During the ball removal control period, at least one of droplet detachment detection monitoring and short-circuit detection monitoring is performed, and the current suppression period T ＩＢ A welding system characterized by reducing the feeding speed of the welding wire when either droplet detachment or a short circuit is detected.

13. A program for performing arc end control during the arc end control period immediately after the welding start signal is switched OFF in arc welding, The arc end control period includes at least an antistick period. The anti-stick period includes at least a droplet removal control period for removing molten metal from the tip of the welding wire, The ball-removal control period begins immediately after the welding start signal is switched to OFF, or a certain period of time after the welding start signal is switched to OFF. A welding system equipped with at least a welding power source, Immediately after the welding start signal is switched OFF, the function changes the welding wire feeding speed from a first wire feeding speed setting value Fs, which is the wire feeding speed setting value during actual welding, to an arbitrary second wire feeding speed setting value Fsa. From the start of the ball-removal control period, the current non-suppression period T for the welding current. ＩＰ and current suppression period T ＩＢ A function that repeats, During the ball removal control period, at least one of droplet detachment detection monitoring and short-circuit detection monitoring is performed, and the current suppression period T ＩＢ A program characterized by having a function that reduces the feeding speed of the welding wire when either droplet separation or a short circuit is detected.

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