Welding power source, welding system, and control method

Abstract

Prevents spatter from scattering. [Solution] A welding power source that controls wire feeding at a constant average feed speed while periodically switching between forward feed and reverse feed is provided with a setting unit, and when the forward feed period is defined as a period during which the wire is fed at a speed higher than the average feed speed and the reverse feed period is defined as a period during which the wire is fed at a speed lower than the average feed speed, the setting unit sets, within the range of the forward feed period, a value for the forward feed acceleration period or a value from which the forward feed acceleration period can be derived, during which the acceleration of the wire in the forward feed direction is positive, and a value for the forward feed deceleration period or a value from which the forward feed deceleration period can be derived, during which the acceleration of the wire in the forward feed direction is negative; or sets, within the range of the reverse feed period, a value for the reverse feed acceleration period or a value from which the reverse feed acceleration period can be derived, during which the acceleration of the wire in the reverse feed direction is positive, and a value for the reverse feed deceleration period or a value from which the reverse feed deceleration period can be derived, during which the acceleration of the wire in the reverse feed direction is negative.

Description

[Technical Field]

[0001] The present invention relates to a welding power source, a welding system, and a control method. [Background technology]

[0002] Conventionally, there is a control method for arc welding in which the tip of a consumable electrode (hereinafter referred to as "wire" or "welding wire") is fed toward a base metal while periodically switching between periods of forward feeding and periods of reverse feeding. This control method is known to be able to reduce spatter by controlling the welding current to vary in accordance with the periodically fluctuating position of the wire tip, and supplying a welding current lower than a predetermined current value during periods when the wire tip is reverse fed. Such a technique is disclosed, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-049506 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed in Patent Document 1 does not take into consideration the period during which the wire tip accelerates or decelerates during the forward feed period or the reverse feed period. For example, as disclosed in Patent Document 1, a wire feed speed is generally adopted such that the period during which the wire tip accelerates and decelerates is equal within the forward feed period, and the period during which the wire tip accelerates and decelerates is equal within the reverse feed period. However, this general method may result in droplets not detaching at the appropriate time during the period during which the wire tip is reversed, i.e., during the low current period. In other words, depending on the welding conditions applied, spatter may increase. Furthermore, although the technology described in Patent Document 1 controls the welding current, controlling other welding conditions such as the arc voltage may also result in droplets not detaching at the appropriate time.

[0005] The object of the present invention is to further reduce spatter in a technology in which welding conditions change according to the periodically fluctuating wire tip position when the wire tip is fed toward the base metal while periodically switching between periods of forward feeding and periods of reverse feeding. [Means for solving the problem]

[0006] The present invention comprises the following configurations.

[0007] (1) A welding power source that controls wire feeding at a constant average feed speed while periodically switching between forward and reverse feed, A setting unit is provided, When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or Within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived is set, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived is set. Welding power supply.

[0008] (2) A welding system including at least a welding power source, which controls wire feed at a constant average feed speed while periodically switching between forward feed and reverse feed, The welding power source includes a setting unit, and the setting unit When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or Within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived is set, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived is set. Welding system.

[0009] (3) A control method for controlling wire feeding at a constant average feeding speed by periodically switching between forward feeding and reverse feeding using a welding power source, comprising: a setting unit provided in the welding power source, When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or a step of setting, within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived, Control method. [Effects of the Invention]

[0010] According to the present invention, in an arc welding control technology in which the tip of a wire is fed toward a base material while periodically switching between periods in which the tip of the wire is fed forward and periods in which the tip of the wire is fed backward, spatter can be further reduced by providing periods in which the tip of the wire is accelerated and decelerated within the period in which the wire is fed forward, and by providing periods in which the tip of the wire is accelerated and decelerated within the period in which the wire is fed backward. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a welding system according to this embodiment. [Figure 2] FIG. 2 is a block diagram showing a schematic configuration relating to the control of the welding power source, welding control device, and servo amplifier in this embodiment. [Figure 3] FIG. 3 is a waveform diagram showing the change over time in acceleration of the tip of the wire in Patent Document 1. [Figure 4] FIG. 4 is a waveform diagram showing the change over time in acceleration of the wire tip in this embodiment. [Figure 5] FIG. 5 is a waveform diagram showing the change over time in the velocity of the wire tip in Patent Document 1. [Figure 6] FIG. 6 is a waveform diagram showing the change over time in the velocity of the wire tip in this embodiment. [Figure 7] FIG. 7 is a waveform diagram showing the change over time in the position of the wire tip in Patent Document 1. [Figure 8] FIG. 8 is a waveform diagram showing the change over time in the position of the wire tip in this embodiment. [Figure 9] FIG. 9 is a graph showing the results of measuring the time from the start of supply of a welding current lower than the predetermined current value in Patent Document 1 until droplet detachment. [Figure 10] FIG. 10 is a graph showing the results of measuring the time from the start of supply of a welding current lower than a predetermined current value to droplet detachment in this embodiment. [Figure 11] FIG. 11 is a waveform diagram showing the change over time in acceleration of the wire tip in this embodiment. [Figure 12] FIG. 12 is a waveform diagram showing the change over time in the velocity of the wire tip in this embodiment. [Figure 13] FIG. 13 is a waveform diagram showing the change over time in the position of the wire tip in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0013] Note that this embodiment is an example of a case where a welding robot is used, and the welding control method according to the present disclosure is not limited to the configuration of this embodiment. For example, an automatic welding device using a cart instead of a welding robot body may be applied, or a portable small welding robot may be applied.

[0014] In this embodiment, a gas metal arc welding method using a welding wire as a consumable electrode among gas shielded arc welding methods will be described.

[0015] 1 is a schematic diagram showing the configuration of a welding system according to this embodiment. Welding system 50 includes welding robot 110, robot control device 120, welding power source 140, controller 150, servo amplifier 160, servo motor 170, push motor 180, and wire buffer 190. Servo motor 170 and push motor 180 feed welding wire 100.

[0016] Welding power source 140 is connected to welding robot 110 via a positive power cable so that current can be applied to welding wire 100, and is connected to workpiece (hereinafter also referred to as "base material") 200 via a negative power cable. This connection is for welding with reverse polarity. To perform welding with positive polarity, the polarity of welding power source 140 can be reversed.

[0017] Furthermore, welding power source 140 and push motor 180 are connected by a signal line, and the feed speed of the welding wire can be controlled.

[0018] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a current-carrying mechanism, i.e., a contact tip, that applies current to the welding wire 100. When current is applied from the contact tip, the welding wire 100 generates an arc from its tip, and the generated heat welds the workpiece 200, which is the welding target.

[0019] The welding torch 111 includes a shielding gas nozzle that serves as a mechanism for ejecting shielding gas. The shielding gas is supplied from a shielding gas supply device (not shown).

[0020] Servo motor 170 is provided near welding torch 111. Servo amplifier 160 connected to servo motor 170 controls servo motor 170. In this embodiment, welding torch 111 is configured independent of servo motor 170, but welding torch 111 may be configured to include servo motor 170 within it. Servo motor 170 switches between forward and reverse rotation based on a forward / reverse feed command to control the feed. Servo amplifier 160 also enables high-speed calculation processing and includes a forward / reverse feed command generation unit 161, as described below.

[0021] A wire buffer 190 is disposed between the servo motor 170 and the push motor 180. The servo motor 170 feeds the welding wire 100 in both forward and reverse directions, while the push motor 180 feeds the welding wire 100 only in the forward direction, which may result in different feeding directions between the servo motor 170 and the push motor 180. This may result in a situation where a large load is likely to be applied to the welding wire 100 within the feeding path. To enable appropriate feeding control even in such feeding situations, the wire buffer 190 is provided to suppress buckling of the wire.

[0022] The welding wire 100 used in this embodiment is not particularly limited. For example, either a solid wire containing no flux or a flux-cored wire containing flux may be used. The material of the welding wire 100 is also not limited. For example, the material may be mild steel, stainless steel, aluminum, or titanium, and the wire surface may be plated with Cu or the like. The diameter of the welding wire 100 is also not particularly limited. In this embodiment, the upper limit of the diameter is preferably 1.6 mm and the lower limit is preferably 0.8 mm.

[0023] In this embodiment, the specific configuration of workpiece 200 is not particularly important, and neither are the welding conditions such as joint shape, welding posture, and groove shape. Robot control device 120 mainly controls the operation of welding robot 110. Therefore, robot control device 120 may also be referred to as a robot controller. Robot control device 120 holds teaching patterns that predefine the operation pattern, welding start position, welding end position, welding conditions, weaving operation, etc. of welding robot 110, and instructs welding robot 110 on these to control the operation of welding robot 110. Furthermore, robot control device 120 provides welding conditions such as welding current, arc voltage, and feed speed to welding power source 140 during welding work in accordance with the teaching data.

[0024] As shown in FIG. 1 , welding system 50 of this embodiment has a configuration in which robot control device 120 is independent from welding power source 140, but it may also be configured such that robot control device 120 is provided within welding power source 140. Controller 150 is connected to robot control device 120 and performs tasks such as creating or displaying a program for operating welding robot 110 and inputting teaching data. Information input by a user to controller 150 is provided to robot control device 120. Controller 150 may also have a function for manually operating welding robot 110. The connection between controller 150 and robot control device 120 may be wired or wireless.

[0025] In response to a command from robot control device 120, welding power source 140 supplies power to welding wire 100 and workpiece 200, thereby generating an arc between welding wire 100 and workpiece 200. In addition, in response to a command from robot control device 120, welding power source 140 outputs a control signal for push motor 180.

[0026] Next, the functional configuration of welding system 50 according to this embodiment will be described in detail with reference to Fig. 2. Fig. 2 is a block diagram showing a schematic configuration relating to the control of welding power source 140, robot control device 120, and servo amplifier 160 according to this embodiment.

[0027] In the present invention, a device or a group of devices having a function related to feed control is referred to as a “feed control device.” In this embodiment, the feed control device is configured by welding power source 140, robot control device 120, and servo amplifier 160, which are related to feed control.

[0028] Welding power source 140 is connected to robot controller 120 via digital communication, and robot controller 120 is connected to servo amplifier 160 via digital communication. That is, servo amplifier 160, robot controller 120, and welding power source 140 are digitally connected in this order in a line configuration. This can be interpreted as a state in which servo amplifier 160 and welding power source 140 are indirectly connected via digital communication. Note that servo amplifier 160, welding power source 140, and robot controller 120 may also be connected in this order in a line configuration. This can be interpreted as a state in which servo amplifier 160 and welding power source 140 are directly connected via digital communication.

[0029] In this embodiment, communication between welding power source 140 and robot control device 120 is performed using CAN (Controller Area Network), which is one of industrial field networks, and communication between robot control device 120 and servo amplifier 160 is performed using EtherCAT (Ethernet for Control Automation Technology) (registered trademark), which is also one of industrial field networks, but this is not limited to these.

[0030] (Functional configuration of welding power source) The control system 141 of the welding power source 140 is executed, for example, by the robot control device 120 or a computer (not shown) executing a program. The control system 141 includes a setting unit that sets values ​​from which a forward feed acceleration period, a forward feed deceleration period, a reverse feed acceleration period, and a reverse feed deceleration period can be derived, as described below. In this embodiment, this setting unit refers to the waveform control table linear calculation unit 37, which will be described later. Note that in this embodiment, the values ​​from which a forward feed acceleration period, a forward feed deceleration period, a reverse feed acceleration period, and a reverse feed deceleration period are set. However, the values ​​of the forward feed acceleration period, the forward feed deceleration period, the reverse feed acceleration period, and the reverse feed deceleration period may also be used as setting values. Furthermore, there is no particular limitation on how values ​​are input during setting. For example, the setting may be performed by a user entering values. A database or table data that stores set values ​​may exist, and the value may be extracted from the database or table data, etc. Alternatively, the value may be set according to various conditions such as frequency conditions. The set value may be a fixed value, or may be a value that varies according to some detected value obtained during welding.

[0031] The control system 141 also corresponds to a welding condition control means for changing at least one welding condition depending on the wire tip position. The welding condition controlled by the welding condition control means is not particularly limited, but examples thereof include welding current, arc voltage, wire feed rate, welding speed, gas flow rate, and weaving conditions. As in this embodiment, it is preferable to control at least the welding current as the condition that can most effectively reduce spatter generation. The welding condition control means at least provides a current section lower than the average welding current within the reverse feed period. The average welding current here may be a preset current value.

[0032] The control system 141 of the welding power source 140 includes a current setting unit 36. In this embodiment, the current setting unit 36 ​​has a function of setting various current values ​​that define the welding current flowing through the welding wire 100. The current setting unit 36 ​​has a function of setting the start and end times of each period of current control. The current setting unit 36 ​​has 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 a function of setting the start and end times of each period of the peak period Dap, the fall period Ddwn, the base period Db, and the rise period Dup related to the current control. The wire tip position conversion unit 36B has a function of obtaining information on the tip position of the welding wire 100.

[0033] The various condition settings may be determined based on, for example, setting values ​​input in advance by an operator, a waveform control table prepared in advance, a database of welding conditions, etc. The setting values, table, database, etc. may be stored in any of the components of welding system 50. The setting values, table, database, etc. may be stored in, for example, robot control device 120, welding power source 140, etc.

[0034] Various condition settings for the peak period Dap, the fall period Ddwn, the base period Db, and the rise period Dup related to the high current period TIP (in this embodiment, the sum of the Dup and Dap periods), the low current period TIB (in this embodiment, the sum of the Ddwn and Db periods), and the wire amplitude W stored in the feed setting data section f , Wire forward / reverse frequency S f , wire forward / reverse cycle T fVarious settings such as a value from which the forward feed acceleration period can be derived, a value from which the forward feed deceleration period can be derived, and a value from which the reverse feed acceleration period can be derived may be determined by the waveform control table linear calculation unit 37 based on a waveform control table prepared in advance. In this embodiment, the set value of the average feed speed Favg is input to the waveform control table linear calculation unit 37, and the waveform control table is provided so that various set values ​​are determined based on the average feed speed Favg, but the present invention is not limited to this, and a waveform control table may be provided so that various set values ​​are determined based on at least one of the welding conditions. In this embodiment, the various condition settings refer to the setting of conditions such as current value, time, phase, etc. In this manner, the waveform control table linear calculation unit 37 is a setting unit that performs various settings.

[0035] The welding current exhibits a pulse waveform in which a high-current period TIP and a low-current period TIB are alternately repeated based on a phase related to the wire tip position (hereinafter referred to as the "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 of 0 to 360° (0 to 2π), where 0° is the angle when the wire tip position is closest to the contact tip and 180° is the angle when the wire tip position is closest to the base metal. The above wire position phase can also be expressed as the case where the wire position phase based on the tip position of the welding wire at the time of switching from the reverse feed period to the forward feed period is set to 0°.

[0036] The average feed rate F in the welding condition information stored by the control system unit 141 avg Based on the set values, the set current value Iap (hereinafter also referred to as "peak current Iap") of the peak period Dap in the high current period TIP and the set current value Ib (hereinafter also referred to as "base current Ib") of the base period Db in the low current period TIB calculated by the waveform control table linear calculation unit 37 are set in the current setting unit 36.

[0037] In this embodiment, the welding current is basically controlled by two values: the peak current Iap and the base current Ib. Therefore, the start time of the low current period TIB, i.e., the time when the current transitions to the base current Ib, may be expressed as the low current start time. The end time of the low current period TIB may be expressed as the time when the base current Ib ends, i.e., the low current end time. The duration (time) of the fall period Ddwn and the duration (time) of the base period Db, which relate to the start and end times of the low current period TIB, are calculated by the waveform control table linear calculation unit 37. The start time of the high current period TIP, i.e., the start time of the rise period Dup, may be expressed as the high current start time, and the end time of the high current period TIP may be expressed as the high current end time.

[0038] Note that the various start times, end times, etc. described above are explained based on time. However, processing may be performed by converting the value of the wire position phase into time or the cycle cyc, using the value of the wire position phase as the reference. In other words, since the values ​​of the wire position phase, time, and cycle cyc are mutually convertible, control may be performed based on any value.

[0039] Furthermore, the wire tip position converter 36B determines the wire tip position based on the phase synchronization signal and the phase delay correction amount signal from the servo amplifier 160. In this embodiment, the wire tip position may be expressed using an angle (0 to 2π) as the wire position phase.

[0040] The phase delay correction amount signal is output from the phase delay correction unit 38. The phase delay correction unit 38 has a database (not shown). This database stores data that is calculated in advance for each welding condition, the difference between periodic setting information and the operation signal of the actual forward / reverse feed operation of the servo motor 170. For example, when the welding condition is a wire forward / reverse frequency S f If the wire forward / reverse frequency S is fThe amount of phase delay correction is determined based on the database in accordance with the value of , and is output from the phase delay correction unit 38 as a phase delay correction amount signal.

[0041] The main power supply circuit of the welding power supply 140 is composed of a three-phase AC power supply (hereinafter also referred to as "AC power supply") 1, a primary side rectifier 2, a smoothing capacitor 3, a switching element 4, a transformer 5, a secondary side rectifier 6, and a reactor 7.

[0042] AC power input from AC power supply 1 is full-wave rectified by primary-side rectifier 2, and further smoothed by smoothing capacitor 3 to be converted into DC power. Next, the DC power is converted into high-frequency AC power by inverter control using switching element 4, and then converted into secondary-side power via transformer 5. The AC output of transformer 5 is full-wave rectified by secondary-side rectifier 6, and further smoothed by reactor 7. The output current of reactor 7 is given to the contact tip as an output from the main power supply circuit, and is passed through welding wire 100, which serves as a consumable electrode.

[0043] The welding wire 100 is fed by the push motor 180 and the servo motor 170, and an arc is generated between the welding wire 100 and the base material 200. The welding wire 100 is fed at an average feeding speed F avg The period during which the welding wire 100 is fed at a value higher than the average feeding speed F avg The period during which the welding wire 100 is fed at a value lower than the forward feed period is defined as the reverse feed period. In this embodiment, the feeding motor periodically feeds the welding wire 100, with the forward feed period and the reverse feed period combined being one cycle. Note that the tip of the welding wire generally refers to the tip of the wire when ignoring the presence of droplets hanging down from the wire tip. In other words, the wire melted by the arc is considered to have immediately transferred to the base material 200.

[0044] The feeding of the welding wire 100 by the push motor 180 is controlled by a control signal from the push feeder control unit 39. The average value of the 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 source 140.

[0045] Further, 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, i.e., a gap portion where the wire can escape if it becomes loose due to feeding between the motors, so as to prevent a large load from being applied to the wire in the feeding path between the push motor 180 and the servo motor 170. An absolute encoder, which is a sensor built into the wire buffer 190, detects the amount of wire buffered as a rotation angle. The detected value is converted into an analog signal by a serial-to-analog converter 191, and an electrical angle calculation unit calculates the electrical angle. The calculated electrical angle is input to an A / D input unit 40 of the welding power source.

[0046] A differential signal obtained by calculating the difference between the electrical angle from the A / D input unit 40 and a reference value of the electrical angle preset in the electrical angle adjustment unit 41 is input to the push feeder control unit 39. Based on this differential signal, the push feeder control unit 39 controls the push motor 180 to buffer an appropriate amount of wire, thereby performing interference control to prevent a large load from being placed on the feeding system. Note that, although the interference control described above is performed in this embodiment, it is not limited to this. Also, although an absolute encoder built into the wire buffer 190 is used in this embodiment, 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 may not be provided.

[0047] A voltage setting signal Vap, which is a target value of the voltage to be applied between the contact tip and the base material 200, is given to the current setting section 36 from a voltage setting section 36C.

[0048] On the other hand, the voltage detection signal Vo is an actual measurement value. In this embodiment, the voltage detection signal Vo passes through a low-pass filter LPF, passes through a separation detection unit 33 (described later), and is input to the current setting unit 36 ​​together with a separation detection signal DTR (described later). Note that 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 amplified signal.

[0049] The current setting unit 36 ​​controls the welding current during the peak period Dap so that the length of the arc (hereinafter also referred to as "arc length") remains constant. The current setting unit 36 ​​determines and sets at least the peak period, rise period, base period, and rising period based on the voltage setting signal Vap and the voltage detection signal Vo. The values ​​of the peak current Ip and the base current Ib may be reset. A current setting signal CCset corresponding to the set period or value is output to the current error amplifier (PWM) 34.

[0050] The current error amplifier 34 amplifies the difference between the current setting signal CCset given as a target value and the current detection signal Io detected by the current detector 31, and outputs the amplified current error signal Ed to the inverter driver 30. The inverter driver 30 corrects the drive signal Ec of the switching element 4 using the current error amplified signal Ed.

[0051] A detachment detection signal DTR, which is a signal for detecting the detachment of a droplet from the tip of the welding wire 100, is also input to the current setting unit 36. The detachment detection signal DTR is output from the detachment detection unit 33. The detachment detection unit 33 monitors a change in the voltage detection signal Vo output by the voltage detection unit 32, and detects the detachment of a droplet from the welding wire 100 from the change. Note that the detachment detection unit 33 is an example of a detection means.

[0052] The detachment detection unit 33 detects droplet detachment by, for example, differentiating or second-order differentiating the voltage detection signal Vo after passing it through an LPF and comparing the result with a predetermined detection threshold value. The detection threshold value is pre-stored in a memory unit (not shown). The detachment detection unit 33 may also generate the detachment detection signal DTR based on a change in resistance value calculated from the voltage detection signal Vo and the current detection signal Io, which are actual measured values.

[0053] The waveform control table linear calculation unit 37 calculates the average feed speed F of the welding wire 100 being fed. avg is given. The average feeding speed F avg are stored in advance in feed setting data unit 35. In this embodiment, feed setting data unit 35 is located within welding power source 140, but various information related to feed settings may be stored in robot control device 120, and the various information may be output from robot control device 120 to welding power source 140.

[0054] The waveform control table linear calculation unit 37 calculates the given average feed speed F avg Based on this, the controller 31 determines values ​​for the peak current Ip, the base current Ib, the time when the base current Ib starts, the time when the base current Ib ends, and the like, and outputs these values ​​to the current setting unit 36. As described above, since the values ​​of the wire position phase, time, and cycle cyc can be converted into each other, the setting value of the base start phase, etc. may be converted into a value of time or cycle cyc, and the converted value may be output to the current setting unit 36.

[0055] In this embodiment, the average feeding speed F avg is input to the waveform control table linear calculation unit 37, but the average feeding speed F avg The value relating to the average feeding speed F is input to the waveform control table linear calculation unit 37 as a set value, and the waveform control table linear calculation unit 37 calculates the set value as the average feeding speed F avg For example, the average feeding speed F avg and the average feed rate F avgWhen a database of average current values ​​that enable optimal welding for the welding speed F is stored, the average current value is used as the setting value, and the setting value is set to the average feed speed F avg may be used in place of the above.

[0056] The feed setting data section 35 is configured to set the average feed speed F avg In addition, the wire amplitude W f , Wire forward / reverse frequency S f , wire forward / reverse cycle T f , and set values ​​of the forward feed acceleration period ratio FAPR and the reverse feed acceleration period ratio RAPR, which will be described later, may be stored. f , Wire forward / reverse frequency S f , and the wire forward / reverse cycle T f is the input average feed rate F avg The feed setting data unit 35 may also store other setting values ​​as the feed setting data.

[0057] In this embodiment, the average feeding speed F avg The period when the feeding speed is higher than the average feeding speed F avg The period during which the feeding speed is lower than the average feeding speed F is defined as a reverse feeding period, and the forward feeding period and the reverse feeding period alternate (hereinafter referred to as "amplitude feeding"). avg The period when the feeding rate is lower than the average feeding rate F avg It refers to a negative feed speed, i.e., a speed at which the wire tip moves in the opposite direction to the position of the base material 200. f is the average feed rate F avg The change range for the wire forward / reverse cycle T f gives the time of change of the wire amplitude, which is the repeating unit. The wire forward / reverse frequency S f is the wire forward / reverse cycle T f is the reciprocal of

[0058] In addition, the wire feeding in Patent Document 1 is performed at an average feeding speed F avg The normal feeding period is a period in which the feeding rate is greater than the average feeding rate F avgIn this feeding method, forward feeding periods, in which the feeding speed is slower than the forward feeding period, and reverse feeding periods, in which the feeding speed is slower than the forward feeding period, appear alternately, and the periods in which the wire tip is accelerated and decelerated during the forward feeding periods are equal, and the periods in which the wire tip is accelerated and decelerated during the reverse feeding periods are equal.

[0059] In contrast to this, in this embodiment, the period during which the acceleration of the wire tip in the forward feed direction during the forward feed period is positive is called the forward feed acceleration period P fa The period during which the acceleration of the wire tip in the positive feed direction becomes negative is called the positive feed deceleration period P fb When this is the case, the ratio of the accelerated forward feed period to the normal feed period is defined as the normal feed acceleration period ratio FAPR, which is expressed by the following formula:

[0060]

number

[0061] The period during which the acceleration of the wire tip in the reverse feed direction becomes positive is called the reverse feed acceleration period P ra The period during which the acceleration of the wire tip in the reverse feed direction becomes negative is called the reverse feed deceleration period P rb When this is the case, the ratio of the reverse feed acceleration period to the reverse feed period is defined as the reverse feed acceleration period ratio RAPR, which is expressed by the following formula:

[0062]

number

[0063] The average feeding speed F stored in the feeding setting data section 35 avg , wire amplitude W f , Wire forward / reverse frequency S f , wire forward / reverse cycle T fThe forward feed acceleration period ratio FAPR and the reverse feed acceleration period ratio RAPR are input from the digital communication unit 42 to the digital communication unit 122 of the robot control device 120. In this embodiment, the forward feed acceleration period ratio FAPR and the reverse feed acceleration period ratio RAPR are stored in the feed setting data unit 35. For example, fa , positive feed deceleration period P fb , reverse feed acceleration period P ra and reverse feed deceleration period P rb In this embodiment, the feeding setting data is communicated by CAN communication.

[0064] The average feeding speed F stored in the feeding setting data section 35 avg , wire amplitude W f , Wire forward / reverse frequency S f , wire forward / reverse cycle T f The forward feed acceleration period ratio FAPR and the reverse feed acceleration period ratio RAPR are input from the digital communication unit 42 to the digital communication unit 122 of the robot control device 120. In this embodiment, communication of these feed setting data is performed by CAN communication.

[0065] Welding sequence unit 43 processes each task in the following order based on the teaching data: idle, gas flow, arc start, welding in progress, and anti-stick. For convenience, in Fig. 2, the welding condition information held by robot control device 120 is also shown enclosed by a dashed line within welding power source 140.

[0066] (Functional configuration of the robot control device) As described above, the digital communication unit 122 of the robot control device 120 receives the average feed speed F avg , wire amplitude W f , Wire forward / reverse frequency S f , wire forward / reverse cycle T f, forward feed acceleration period ratio FAPR, reverse feed acceleration period ratio RAPR, and other feed setting data are input. 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 via EtherCAT (registered trademark) communication.

[0067] (Servo amplifier functional configuration) The digital communication unit 162 of the servo amplifier 160 receives the average feeding speed F avg , wire amplitude W f , Wire forward / reverse frequency S f , wire forward / reverse cycle T f , forward feed acceleration period ratio FAPR, reverse feed acceleration period ratio RAPR, etc. A forward / reverse feed command generating unit 161 of the servo amplifier 160 generates a feed command for forward feed or reverse feed based on the setting information input by digital communication, i.e., the feed setting data.

[0068] The forward / reverse feeding command generation unit 161 generates a wire forward / reverse period T. f , forward feed acceleration period ratio FAPR and reverse feed acceleration period ratio RAPR, fa , positive feed deceleration period P fb , reverse feed acceleration period P ra and reverse feed deceleration period P rb In addition, in the feed setting data section 35, the normal feed acceleration period P fa , positive feed deceleration period P fb , reverse feed acceleration period P ra and reverse feed deceleration period P rb If the value of is stored, it does not need to be calculated.

[0069] Positive feed acceleration period P fa , positive feed deceleration period P fb , reverse feed acceleration period P ra and reverse feed deceleration period P rb is given by the following equation:

[0070]

number

[0071] In the above example, the positive feed acceleration period P fa , positive feed deceleration period P fb , reverse feed acceleration period P ra and reverse feed deceleration period P rb , respectively, and the wire forward / reverse cycle T f , can be derived based on the forward feed acceleration period ratio FAPR and the reverse feed acceleration period ratio RAPR. f , the forward feed acceleration period ratio FAPR and the reverse feed acceleration period ratio RAPR are fa , positive feed deceleration period P fb , reverse feed acceleration period P ra and reverse feed deceleration period P rb corresponds to a value that can be derived.

[0072] The forward feeding period and the reverse feeding period are equal, and the forward feeding acceleration period P fa and reverse feed deceleration period P rb and the normal feed deceleration period P fb and the reverse feed acceleration period P ra When the values ​​of the forward feeding acceleration period ratio FAPR and the reverse feeding acceleration period ratio RAPR are equal to each other, when one of the values ​​is set, the other value is also determined.

[0073] The forward / reverse feed command generating unit 161 determines the wire amplitude W f , positive feed acceleration period P fa , positive feed deceleration period P fb , reverse feed acceleration period P ra and reverse feed deceleration period P rb In this embodiment, the forward / reverse feed command generating unit 161 starts calculating the amplitude feed speed Ff from the forward feed period, but may start calculating the amplitude feed speed Ff from the reverse feed period.

[0074] Positive feed acceleration period P faAmplitude feed rate F f is given by the following equation, where t represents time.

[0075]

number

[0076] Here, T0 is the start time of the wire forward / reverse cycle and the start time of the forward feeding acceleration period. Time t is T0+P fa If this is the case, the normal feed deceleration period P fb The normal feed deceleration period P fb Amplitude feed rate F f is given by the following equation:

[0077]

number

[0078] where T1 is the start time of the positive feed deceleration period, T1 = T0 + P fa Time t is T1+P fb If this occurs, the reverse feed acceleration period P ra The reverse feed acceleration period P ra Amplitude feed rate F f is given by the following equation:

[0079]

number

[0080] where T2 is the start time of the reverse feed acceleration period, T2 = T1 + P fb Time t is T2+P ra If this occurs, the reverse feed deceleration period P rb The reverse feed deceleration period P rb Amplitude feed rate F f is given by the following equation:

[0081]

number

[0082] where T3 is the start time of the reverse feed deceleration period, T3 = T2 + P ra Time t is T3+P rb If this is the case, the normal feeding acceleration period P fa Transition to.

[0083] The forward / reverse feed command generation unit 161 generates an amplitude feed speed F f Calculate the amplitude feed rate F f and average feeding speed F avg Based on this, the feed speed command signal F w is output to the servo motor 170.

[0084] In this embodiment, the feeding speed command signal F w is expressed by the following equation: F w =F f +F avg ...Formula (A)

[0085] Furthermore, the forward / reverse feed command generating unit 161 may detect at which wire position phase in amplitude feeding the separation has occurred based on the separation detection signal DTR given from the separation detection unit 33. However, the feed speed command signal F w is limited to the case where the separation of a droplet from the tip of the welding wire 100 is detected within the expected period. If the separation of a droplet is not detected within the expected period, the forward / reverse feed command generating unit 161 generates the feed speed command signal F w For example, the forward / reverse feed command generating unit 161 may switch the feed speed command signal F w The average feeding speed F avg Switch to feeding by average feeding speed F avg The switching from the feeding control by equation (A) to the feeding control expressed by equation (B) is determined according to the timing at which the detachment of the droplet is detected.

[0086] The servo amplifier 160 receives a feed speed command signal F wThe servo amplifier 160 performs inverter control of the servo motor 170 based on the feed speed command signal F. The synchronization signal generator 163 of the servo amplifier 160 outputs a phase synchronization signal to the welding power source 140. The phase synchronization signal is generated based on the feed speed command signal F. w is generated based on

[0087] Note that welding power source 140 and synchronization signal generator 163 of servo amplifier 160 may be connected at least via an analog input / output. In this case, a synchronization signal is input to welding power source 140 from servo amplifier 160 via the analog input / output. Average feed speed F avg , wire amplitude W f , Wire forward / reverse frequency S f , wire forward / reverse cycle T f By transmitting feed setting data such as the forward feed acceleration period ratio FAPR and the reverse feed acceleration period ratio RAPR via digital communication, while transmitting the synchronization signal via analog communication, digital communication and analog communication can be used efficiently depending on the application.

[0088] 3 and 4 are waveform diagrams showing the change over time in the acceleration of the wire tip. FIG. 3 is a waveform diagram of Patent Document 1, and FIG. 4 is a waveform diagram of this embodiment. The horizontal axis represents time, and the wire forward / reverse cycle T f is converted into a phase using 2π. The vertical axis represents the acceleration of the wire tip, with positive values ​​representing acceleration in the forward feed direction and negative values ​​representing acceleration in the reverse feed direction.

[0089] Referring to Figure 3, in Patent Document 1, the absolute values ​​of the acceleration of the wire tip are equal between the forward feeding period and the reverse feeding period, and the acceleration and deceleration periods are symmetrical. Specifically, during the forward feeding period, the wire tip accelerates from 0 to π / 2 and decelerates from π / 2 to π. Similarly, during the reverse feeding period, the wire tip accelerates from π to 3π / 2 and decelerates from 3π / 2 to 2π.

[0090] On the other hand, in the present embodiment shown in Fig. 4, it can be seen that the absolute value of the acceleration of the wire tip during the forward feed period is smaller than the absolute value of the acceleration of the wire tip during the reverse feed period, the acceleration period of the wire tip during the forward feed period is longer than the deceleration period, and the acceleration period of the wire tip during the reverse feed period is shorter than the deceleration period. Specifically, during the forward feed period, the wire tip accelerates from 0 to a phase greater than π / 2 and then decelerates in a short period from a phase greater than π / 2 to π. During the reverse feed period, the wire tip accelerates in a short period from π to a phase less than 3π / 2 and then decelerates in a long period from a phase less than 3π / 2 to π.

[0091] In this way, it is preferable to control the absolute value of the wire tip acceleration asymmetrically between the forward feed period and the reverse feed period. In this embodiment, by keeping the absolute value of the wire tip acceleration small during the forward feed period, the wire tip tends to stably hold the droplet. On the other hand, by increasing the absolute value of the wire tip acceleration during the reverse feed period, the droplet and the wire tip tend to separate instantaneously.

[0092] 5 and 6 are waveform diagrams showing the time change in the velocity of the wire tip. FIG. 5 is a waveform diagram of Patent Document 1, and FIG. 6 is a waveform diagram of this embodiment. The horizontal axis represents time, and the wire forward / reverse cycle T f is converted into a phase by 2π. The vertical axis represents the speed of the wire tip, with positive values ​​representing speed in the forward feed direction and negative values ​​representing speed in the reverse feed direction. Between 0 and π, the speed of the wire tip is the average speed F avg The period when the wire tip speed is higher than the average speed F avg The period during which the temperature is lower than the reference temperature is the reverse feed period.

[0093] 5, in Patent Document 1, the phase at which the absolute value of the wire tip speed is maximum during the forward feed period is π / 2, and the phase at which the absolute value of the wire tip speed is maximum during the reverse feed period is 3π / 2. This shows that the wire tip speed changes symmetrically during the forward feed period and the reverse feed period.

[0094] On the other hand, in the present embodiment shown in Figure 6, the phase in which the absolute value of the wire tip velocity is maximum during the forward feeding period is greater than π / 2, and the phase in which the absolute value of the wire tip velocity is maximum during the reverse feeding period is smaller than 3π / 2. Specifically, during the forward feeding period, the wire tip velocity gradually increases from 0 to a phase greater than π / 2 and then rapidly decreases over a short period from a phase greater than π / 2 to π. During the reverse feeding period, the wire tip velocity rapidly increases over a short period from π to a phase less than 3π / 2 and then gradually decreases over a long period from a phase less than 3π / 2 to 2π. In other words, during the forward feeding period, the wire tip velocity gradually increases, reaches a maximum value, and then rapidly decreases, whereas during the reverse feeding period, the wire tip velocity rapidly increases, reaches a maximum value, and then gradually decreases.

[0095] In this way, in this embodiment, by controlling the speed change of the wire tip asymmetrically during the forward feed period and the reverse feed period, droplets can be grown while the wire tip is slowly brought closer to the base material during the forward feed period, and droplets can be detached while the wire tip is quickly moved away from the base material during the reverse feed period.

[0096] 7 and 8 are waveform diagrams showing the change in the position of the wire tip over time under the condition that the wire tip does not melt. Fig. 7 is a waveform diagram of Patent Document 1, and Fig. 8 is a waveform diagram of this embodiment. The horizontal axis represents time, and the wire forward / reverse cycle T f is converted into a phase by 2π. The vertical axis represents the position of the wire tip, with the upward direction representing the direction approaching the base metal and the downward direction representing the direction moving away from the base metal. The wire tip is located at the wire amplitude W f During the reverse feed period, the wire amplitude W f Therefore, the center of the amplitude of the change in the position of the wire tip is W f It is set to the / 2 position.

[0097] Here, the speed of the wire tip is the average feed speed F avgSince the wire tip is offset in the forward feeding direction by this amount, the wire tip position per cycle moves upward by the product of the average feeding speed and the forward / reverse feeding period. In other words, the change in the wire tip position shown in Figures 7 and 8 is a superposition of the changes in the wire tip position during the forward feeding period and the reverse feeding period on an average upward trend.

[0098] Referring to Fig. 7, in Patent Document 1, the phases at which the position of the wire tip is the amplitude center are π / 2 and 3π / 2. In other words, the period in which the position of the wire tip is closer to the base material than the amplitude center is equal to the period in which the position of the wire tip is farther from the base material than the amplitude center. Specifically, in the periods from 0 to π / 2 and from 3π / 2 to 2π, the position of the wire tip is closer to the amplitude center W f / 2, and in the period from π / 2 to 3π / 2, the position of the wire tip is at the amplitude center W f Closer to the base material than / 2.

[0099] On the other hand, in the present embodiment shown in FIG. 8, the position of the wire tip is the amplitude center W f The phase where the wire tip is at the amplitude center W is greater than π / 2 and less than 3π / 2. In other words, the period when the wire tip is closer to the base material than the amplitude center is shorter than the period when the wire tip is farther from the base material than the amplitude center. Specifically, in the period from 0 to a phase greater than π / 2 and from a phase less than 3π / 2 to 2π, the wire tip is at the amplitude center W. f When the wire tip is farther from the base material than π / 2 and in the period from a phase greater than π / 2 to a phase less than 3π / 2, the position of the wire tip is at the amplitude center W f Closer to the base material than / 2.

[0100] In this way, the position of the wire tip is the center of amplitude W f By shortening the period during which the wire tip is closer to the base metal than / 2, the risk of the wire tip and droplets at the wire tip coming into contact with the base metal and causing a short circuit can be reduced. This is because if the wire tip gets too close to the base metal, droplets will come into contact with the base metal and a short circuit will easily occur. If a short circuit occurs, the arc will become unstable, causing spatter and welding defects. In Patent Document 1, the position of the wire tip is set at the amplitude center W fIn this embodiment, the position of the wire tip is equal to the amplitude center W f By controlling the period during which the droplets are closer to the base metal to be shorter than / 2, the time during which the droplets are in close proximity to the base metal can be minimized, and the occurrence of short circuits can be effectively prevented.

[0101] Figures 9 and 10 are histograms showing the variation in the time from the start of the low-current period TIB to droplet detachment measured for each forward / reverse wire cycle. The change in arc voltage that occurs when a droplet detaches from the wire tip was used to detect the droplet detachment timing. The numbers at the top of each histogram indicate the value of that histogram. The number of measurements n corresponds to 1,000 forward / reverse wire cycles (n = 1,000), and the time from the start of the low-current period TIB to droplet detachment was measured for 1,000 cycles. The mean μ indicates the average of the measured data, and the standard deviation σ indicates the degree to which the measured data is dispersed from the average. Note that Figure 9 is a graph from Patent Document 1, and Figure 10 is a graph from this embodiment.

[0102] 9, in Patent Document 1, the average μ of the measured data is 2.414 ms and the standard deviation σ is 0.461 ms. In other words, it can be seen that approximately 68% of the time from the start of the low current period TIB to droplet detachment is in the range of 1.953 ms to 2.875 ms.

[0103] 10, in this embodiment, the average μ of the measured data is 2.588 ms, and the standard deviation σ is 0.261 ms. In other words, it can be seen that approximately 68% of the time from the start of the low current period TIB to droplet detachment falls within a range of 2.327 ms to 2.849 ms. Compared to the case of Patent Document 1, it is clear that in this embodiment, approximately 68% of the time from the start of the low current period TIB to droplet detachment falls within a narrower range, indicating that there is a higher probability that a droplet will detach from the wire tip at a specific timing.

[0104] In this way, it was demonstrated that the present embodiment has a higher probability of droplets detaching from the wire tip at a specific timing than the technology of Patent Document 1. The spatter reduction effect is thought to be due to the fact that the droplet detachment timing is concentrated, which makes it easier to balance the wire melting rate due to the heat input per wire forward / reverse cycle and the average wire feed speed, thereby stabilizing the arc length.

[0105] (Variation) Fig. 11 is a waveform diagram showing the change over time in the acceleration of the wire tip in this embodiment. Fig. 12 is a waveform diagram showing the change over time in the velocity of the wire tip in this embodiment. Fig. 13 is a waveform diagram showing the change over time in the position of the wire tip in this embodiment. Figs. 11, 12, and 13 are diagrams showing modified examples corresponding to Figs. 4, 6, and 8, respectively.

[0106] The forward feeding period and the reverse feeding period can be adjusted separately. Figures 11, 12, and 13 show the case where only the forward feeding period is adjusted in length. That is, the forward feeding deceleration period P fb is the normal feeding acceleration period P fa The reverse feed acceleration period P ra and reverse feed deceleration period P rb Contrary to what is shown in the figure, the length of the reverse feed period may be different only in the reverse feed acceleration period P ra is the reverse feed deceleration period P rb The period is adjusted to be smaller than the normal feeding acceleration period P fa and the normal feed deceleration period P fb The length of the period may remain the same.

[0107] The forward feed period and the reverse feed period may have different lengths. When the forward feed period and the reverse feed period have different lengths, the setting unit may further set a forward / reverse feed ratio indicating the ratio between the forward feed period and the reverse feed period. The forward / reverse feed ratio may be defined by any of the following formulas. Forward / reverse feed ratio = (forward feed period / period of one cycle) x 100 (%) Forward / reverse feed ratio = (reverse feed period / period of one cycle) x 100 (%)

[0108] The present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0109] As described above, the present specification discloses the following:

[0110] (1) A welding power source that controls wire feeding at a constant average feed speed while periodically switching between forward and reverse feed, A setting unit is provided, When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or Within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived is set, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived is set. Welding power supply.

[0111] According to this welding power source, in an arc welding control technology in which the tip of the wire is fed toward the base material while periodically switching between periods in which it is fed forward and periods in which it is fed backward, spatter can be further reduced by providing periods in which the wire tip is accelerated and decelerated within the range of the forward feed period, and periods in which the wire tip is accelerated and decelerated within the range of the backward feed period.

[0112] (2) The forward feed acceleration period and the forward feed deceleration period are different from each other, or the reverse feed acceleration period and the reverse feed deceleration period are different from each other. (1) The welding power source described above.

[0113] According to this welding power source, in an arc welding control technology in which the tip of the wire is fed toward the base material while periodically switching between periods in which it is fed forward and periods in which it is fed backward, spatter can be further reduced by providing periods in which the wire tip is accelerated and decelerated within the range of the forward feed period, and periods in which the wire tip is accelerated and decelerated within the range of the backward feed period.

[0114] (3) The setting unit is characterized in that it sets a normal feed acceleration period ratio, which is a ratio of the normal feed acceleration period to the normal feed period as a whole, as a value from which the normal feed acceleration period and the normal feed deceleration period can be derived. A welding power source according to (1) or (2).

[0115] According to this welding power source, even when welding conditions change, the forward feed acceleration period and the forward feed deceleration period can be flexibly determined using the forward feed acceleration period ratio.

[0116] (4) The setting unit is characterized in that it sets a reverse feed acceleration period ratio, which is a ratio of the reverse feed acceleration period to the entire reverse feed period, as a value from which the reverse feed acceleration period and the reverse feed deceleration period can be derived. A welding power source according to (1) or (2).

[0117] According to this welding power source, even when welding conditions change, the reverse feed acceleration period and the reverse feed deceleration period can be flexibly determined using the reverse feed acceleration period ratio.

[0118] (5) When the proportion of the forward feed acceleration period to the whole forward feed period is defined as a forward feed acceleration period ratio, and the proportion of the reverse feed acceleration period to the whole reverse feed period is defined as a reverse feed acceleration period ratio, When one of the forward feed acceleration period ratio and the reverse feed acceleration period ratio is set, the other is determined at the same time. A welding power source according to (3) or (4).

[0119] According to this welding power source, if only one of the forward feed acceleration period ratio and the reverse feed acceleration period ratio is known as a set value, the other can be calculated.

[0120] (6) The welding machine is characterized by comprising a welding condition control means for changing at least one welding condition in accordance with the tip position of the wire. A welding power source according to any one of (1) to (5).

[0121] (7) In the welding condition control means, the welding condition to be controlled is at least the welding current, and at least a current section lower than the average welding current is provided within the range of the reverse feed period. (6) A welding power source according to the present invention.

[0122] These welding power sources enable precise welding according to the position of the tip of the wire.

[0123] (8) The setting unit further sets a forward / reverse feed ratio indicating a ratio between a forward feed period and a reverse feed period, The forward / reverse feed ratio is Forward / reverse feed ratio = (forward feed period / period of one cycle) x 100 (%), or Forward / reverse feed ratio = (reverse feed period / period of one cycle) x 100 (%) A welding power source according to any one of (1) to (7).

[0124] According to this welding power source, the forward feed period and the reverse feed period can be set so that the forward feed period and the reverse feed period have different lengths.

[0125] (9) A welding system including at least a welding power source, which controls wire feeding at a constant average feeding speed while periodically switching between forward feeding and reverse feeding, The welding power source includes a setting unit, and the setting unit When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or Within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived is set, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived is set. Welding system.

[0126] According to this welding system, in an arc welding control technique in which the tip of the wire is fed toward the base material while periodically switching between periods in which it is fed forward and periods in which it is fed backward, spatter can be further reduced by providing periods in which the wire tip is accelerated and decelerated within the period in which it is fed forward, and periods in which the wire tip is accelerated and decelerated within the period in which it is fed backward.

[0127] (10) A control method for controlling wire feeding at a constant average feeding speed by periodically switching between forward feeding and reverse feeding using a welding power source, comprising: a setting unit provided in the welding power source, When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or a step of setting, within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived, Control method.

[0128] According to this control method, in an arc welding control technology in which the tip of the wire is fed toward the base material while periodically switching between periods in which it is fed forward and periods in which it is fed backward, spatter can be further reduced by providing periods in which the wire tip is accelerated and decelerated within the range of the forward feed period, and periods in which the wire tip is accelerated and decelerated within the range of the backward feed period. [Explanation of symbols]

[0129] 1 AC power supply 2 Primary rectifier 3 smoothing capacitors 4 Switching elements 5. Transformer 6 Secondary rectifier 7 Reactor 10 Arc welding system 30 Inverter drive unit 31 Current detection section 32 Voltage detection section 33 Separation detection unit 34 Current error amplifier 35 Feed setting data section 36 Current setting section 36A target current setting section 36B Wire tip position change part 36C Voltage setting section 37 Waveform control table linear calculation section 38 Phase delay correction unit 39 Push feeder control section 40 A / D input section 41 Electrical angle adjustment unit 42 Digital Communications Department 43 Welding Sequence Division 50 Welding System 100 welding wire 110 Welding Robot 111 Welding Torch 120 Robot control device 122 Digital Communications Department 123 Digital Communications Department 140 Welding power source 141 Control System Department 150 Controller 160 Servo amplifier 161 Forward / reverse feed command generation unit 162 Digital Communications Department 163 Synchronization signal generator 170 Servo motor 180 Push Motor 190 Wire Buffer 191 Serial to Analog Converter 200 Work

Claims

1. A welding power source that controls wire feeding at a constant average feeding speed while periodically switching between forward feeding and reverse feeding, A setting unit is provided, When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or Within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived is set, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived is set. Welding power supply.

2. The forward feed acceleration period and the forward feed deceleration period are different from each other, or the reverse feed acceleration period and the reverse feed deceleration period are different from each other.

2. The welding power supply according to claim 1.

3. The setting unit is characterized in that it sets a normal feed acceleration period ratio, which is a ratio of the normal feed acceleration period to the whole normal feed period, as a value from which the normal feed acceleration period and the normal feed deceleration period can be derived.

2. The welding power supply according to claim 1.

4. the setting unit sets a reverse feed acceleration period ratio, which is a ratio of the reverse feed acceleration period to the entire reverse feed period, as a value from which the reverse feed acceleration period and the reverse feed deceleration period can be derived.

2. The welding power supply according to claim 1.

5. When the proportion of the forward feed acceleration period to the entire forward feed period is defined as a forward feed acceleration period ratio, and the proportion of the reverse feed acceleration period to the entire reverse feed period is defined as a reverse feed acceleration period ratio, When one of the forward feed acceleration period ratio and the reverse feed acceleration period ratio is set, the other is determined at the same time.

5. A welding power supply according to claim 3 or 4.

6. The welding machine is characterized in that it comprises a welding condition control means for changing at least one welding condition in accordance with the tip position of the wire.

2. The welding power supply according to claim 1.

7. the welding condition control means controls at least the welding current as a welding condition, and provides at least a current section in which the welding current is lower than an average welding current within the reverse feed period.

7. The welding power supply according to claim 6.

8. The setting unit Further setting a forward / reverse feeding ratio indicating a ratio between a forward feeding period and a reverse feeding period; The forward / reverse feed ratio is Forward / reverse feed ratio=(forward feed period / period of one cycle)×100(%), or Forward / reverse feed ratio=(reverse feed period / period of one cycle)×100(%) 2. The welding power supply according to claim 1.

9. A welding system including at least a welding power source, which controls wire feed at a constant average feed speed while periodically switching between forward feed and reverse feed, The welding power source includes a setting unit, and the setting unit When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or Within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived is set, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived is set. Welding system.

10. A control method for controlling wire feeding at a constant average feeding speed by periodically switching between forward feeding and reverse feeding using a welding power source, comprising: a setting unit provided in the welding power source, When a period during which the wire is fed at a rate higher than the average feed rate is defined as a forward feed period, and a period during which the wire is fed at a rate lower than the average feed rate is defined as a reverse feed period, Within the range of the positive feed period, a value of a positive feed acceleration period in which the acceleration in the positive feed direction of the wire becomes positive or a value from which the positive feed acceleration period can be derived is set, and a value of a positive feed deceleration period in which the acceleration in the positive feed direction of the wire becomes negative or a value from which the positive feed deceleration period can be derived is set, or a step of setting, within the range of the reverse feed period, a value of a reverse feed acceleration period in which the acceleration in the reverse feed direction of the wire becomes positive or a value from which the reverse feed acceleration period can be derived, and a value of a reverse feed deceleration period in which the acceleration in the reverse feed direction of the wire becomes negative or a value from which the reverse feed deceleration period can be derived, Control method.

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