Feed control method, control device, and feed control program

Abstract

In feed control that does not primarily involve short-circuit transfer, the deviation between the target amplitude and the actual amplitude is suppressed, droplet detachment is stabilized, spatter is reduced, and welding quality is improved. [Solution] A feed control method for feeding a welding wire at a predetermined average wire feed speed while periodically repeating forward and reverse feed in accordance with a wire forward / reverse frequency, with a forward feed period and a reverse feed period forming one cycle, includes at least the steps of calculating or measuring an actual amplitude amount of the welding wire or an error amount between the actual amplitude amount and a target amplitude amount, calculating a correction amount based on the actual amplitude amount or the error amount, and calculating an amplitude command value based on the correction amount.

Description

[Technical Field]

[0001] The present invention relates to a feed control method, a control device, and a feed control program for feeding a welding wire at a constant speed while periodically repeating a forward feed period and a reverse feed period. [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 actual feed speed during forward and reverse feed may be attenuated relative to the set value due to factors such as wire feed resistance loads caused by clogging or bending of the conduit cable, or motor loads due to the assembly accuracy of the wire feeder. This attenuation of the actual feed speed may cause a discrepancy between the set conditions and the actual measured value. Note that the amount of this discrepancy varies depending on the wire feed resistance load or motor load, and therefore varies depending on the configuration of the welding system.

[0005] The attenuation of the actual feed rate can cause a discrepancy between the set value and the measured value, for example, due to the amplitude of both amplitudes. These amplitudes are particularly important factors in feed control that does not primarily involve short-circuit transfer. If the measured values ​​of these amplitudes (hereinafter also referred to as "actual amplitudes") differ from the set values ​​(hereinafter also referred to as "target amplitudes"), droplet detachment becomes unstable. In other words, spatter increases during welding.

[0006] Furthermore, if the target amplitude and the actual amplitude differ, the wire movement in one of the feeding directions increases, and the average feed speed also differs from the set value. In other words, there is a problem that the desired deposition amount cannot be obtained, which adversely affects the welding quality.

[0007] However, Patent Document 1 does not take into consideration the influence of wire feeding resistance load and motor load, nor does it take into consideration the problem that occurs when the target amplitude amount and the actual amplitude amount differ due to these influences.

[0008] The object of the present invention is to suppress the difference between the target amplitude amount and the actual amplitude amount, stabilize droplet detachment, reduce spatter, and improve welding quality in feed control that does not primarily involve short-circuit transfer. [Means for solving the problem]

[0009] The present invention comprises the following configurations.

[0010] (1) A feed control method for feeding a welding wire at a predetermined average wire feed speed while periodically repeating forward and reverse feed in accordance with a wire forward / reverse frequency, the forward feed period and the reverse feed period being one cycle, the method comprising: calculating or measuring at least an actual amplitude amount of the welding wire or an error amount between the actual amplitude amount and a target amplitude amount; calculating a correction amount based on the actual amplitude amount or the error amount; calculating an amplitude command value based on the correction amount; A feed control method comprising:

[0011] (2) A control device for controlling the feeding of a welding wire at a predetermined average wire feeding speed while periodically repeating forward and reverse feeding in accordance with a wire forward / reverse frequency, the forward feeding period and the reverse feeding period being one cycle, the control device includes at least an actual amplitude detection unit and a correction amount calculation unit, The real amplitude detection unit a means for detecting an actual feed speed of the welding wire; The measuring device includes a means for calculating an actual amplitude amount calculated based on at least the detected actual feed speed and either a set average feed speed value or an actual measured average feed speed value, The correction amount calculation unit means for calculating a correction amount based on the actual amplitude amount and the target amplitude amount; means for calculating a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value; The control device, characterized in that the actual amplitude amount calculated by the actual amplitude detection unit is at least one of the actual amplitude amount in a forward movement period, the actual amplitude amount in a reverse movement period, and an average actual amplitude amount obtained by averaging the actual amplitude amounts in the forward movement period and the reverse movement period.

[0012] (3) A control device for controlling the feeding of the welding wire at a predetermined average wire feeding speed while periodically repeating forward and reverse feeding in accordance with a wire forward / reverse frequency, the forward feeding period and the reverse feeding period being one cycle, the control device includes at least an amplitude error amount calculation unit and a correction amount calculation unit; The amplitude error amount calculation unit includes means for detecting an actual feed speed of a welding wire; at least a means for calculating a difference between the detected actual feed speed and a reference target feed speed, and for calculating an amplitude error amount as a value obtained by numerically integrating the difference over a predetermined forward / reverse wire cycle, the correction amount calculation unit includes means for calculating, as an amplitude command value, a value obtained by adding the amplitude error amount to a target amplitude amount as a correction amount; A control device comprising:

[0013] (4) A feed control program used to feed a welding wire at a predetermined average wire feed speed while periodically repeating forward and reverse feed in accordance with a wire forward / reverse frequency, the forward feed period and the reverse feed period being one cycle, the program comprising: The control device a function of calculating or measuring at least an actual amplitude amount of the welding wire or an error amount between the actual amplitude amount and a target amplitude amount; a function of calculating a correction amount based on the actual amplitude amount or the error amount; a function of calculating an amplitude command value based on the correction amount; A feed control program that realizes this. [Effects of the Invention]

[0014] According to the present invention, in feed control that does not primarily involve short-circuit transfer, the difference between the target amplitude amount and the actual amplitude amount can be suppressed, thereby stabilizing droplet detachment, reducing spatter, and improving welding quality.

[0015] Furthermore, since the actual amplitude amount is calculated based on the set average speed, when the actual amplitude amounts in the forward and reverse transport periods match, the actual average speed is equal to the set average speed, and the present invention also serves to correct the average speed. [Brief explanation of the drawings]

[0016] [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, the robot control device, and the servo amplifier in this embodiment. [Figure 3] FIG. 3 is a block diagram showing an example of the configuration of a servo amplifier and a servo motor including an amplitude correction unit in this embodiment. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of a servo amplifier and a servo motor including an amplitude correction unit in this embodiment. [Figure 5]FIG. 5 is a diagram showing the relationships between various values ​​for the control device in this embodiment. [Figure 6] FIG. 6 is a diagram showing the results of amplitude correction in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] It should be noted that this embodiment is an example of a case where a welding robot is used, and the feed control method according to the present disclosure is not limited to the configuration of this embodiment.

[0019] 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.

[0020] 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, which is a consumable electrode, 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 weld with positive polarity, the polarity of welding power source 140 can be reversed.

[0021] 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.

[0022] The welding robot 110 is equipped with a welding torch 111 as an end effector. The welding torch 111 has a current-carrying mechanism, i.e., a welding tip, that applies current to the welding wire 100. When current is applied from the welding tip, the welding wire 100 generates an arc from its tip, and the generated heat welds the workpiece 200, which is the welding target. The welding tip is also generally referred to as a contact tip.

[0023] 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).

[0024] 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.

[0025] A wire buffer 190 is disposed between the servo motor 170 and the push motor 180. Because the servo motor 170 feeds the welding wire 100 in both forward and reverse directions and the push motor 180 feeds the welding wire 100 only in the forward direction, the feeding directions of the servo motor 170 and the push motor 180 may differ. 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 a feeding situation, the wire buffer 190 is provided to suppress buckling of the wire.

[0026] 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.

[0027] 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, welding voltage, and feed speed to welding power source 140 during welding work in accordance with the teaching data.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] In this embodiment, communication between welding power source 140 and robot control device 120 is via CAN (Controller Area Network), which is one of the industrial field networks, and communication between robot control device 120 and servo amplifier 160 is via EtherCAT (Ethernet for Control Automation Technology) (registered trademark), which is also one of the industrial field networks, but this is not limited to these.

[0033] (Functional configuration of welding power source) The control system unit 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 unit 141 corresponds to 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. The method of inputting the values ​​in the setting is not particularly limited. For example, the setting may be performed by a user inputting a value. A database or table data that stores the setting values ​​may exist, and the setting may be performed by extracting the value from the database or table data. The value may be set according to various conditions such as frequency conditions. The setting value may be a fixed value or may vary according to some detection value obtained during welding.

[0034] 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.

[0035] 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 robot control device 120, welding power source 140, etc.

[0036] The various condition settings for the peak period Dap, fall period Ddwn, base period Db, and rise period Dup related to the high current period TIP (in this embodiment, the sum of the Dup and Dap periods) and the low current period TIB (in this embodiment, the sum of the Ddwn and Db periods) may be determined by the waveform control table linear calculation unit 37 based on a waveform control table prepared in advance. Note that the various condition settings here mean, in this embodiment, the setting of conditions such as current value, time, or phase.

[0037] 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 tip side and 180° is the angle when the wire tip position is closest to the base metal side. The above wire position phase can also be expressed as a case in which 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°.

[0038] Based on the set value of the average feed rate Favg in the welding condition information stored by the control system unit 141, the set current value Iap (hereinafter also referred to as "peak current Iap") for the peak period Dap in the high current period TIP and the set current value Ib (hereinafter also referred to as "base current Ib") for 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.

[0039] 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 start time of the low current period TIB and the duration (time) of the fall period Ddwn and the duration (time) of the base period Db associated with the end time 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.

[0040] 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.

[0041] 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.

[0042] The phase delay correction amount signal is output from phase delay correction unit 38. 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 servo motor 170. For example, when the welding condition is a wire forward / reverse frequency, the phase delay correction amount is determined based on the database in accordance with the value of the wire forward / reverse frequency to be used, and is output from phase delay correction unit 38 as a phase delay correction amount signal.

[0043] 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.

[0044] 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.

[0045] The welding wire 100 is fed by a push motor 180 and a servo motor 170, generating an arc between the welding wire 100 and the base material 200. A forward feed period during which the tip of the welding wire 100 moves toward the base material 200 is referred to as a forward feed period TP. A reverse feed period during which the tip of the welding wire 100 moves in a direction opposite to the direction in which the base material 200 is located is referred to as a reverse feed period TN. In this embodiment, the feed motor periodically feeds the welding wire 100, with the forward feed period TP and the reverse feed period TN combined forming one cycle. Note that the tip of the welding wire usually refers to the tip of the wire when ignoring the presence of droplets hanging from the wire tip. In other words, the wire melted by the arc is considered to have immediately transferred to the base material 200.

[0046] 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.

[0047] Further, the push feeder control unit 39 performs control in accordance with 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 into which the wire can escape if it becomes loose due to the influence of feeding between the motors) so that a large load is not applied to the wire in the feeding path between the push motor 180 and the servo motor 170, and an absolute encoder, which is a sensor built into the wire buffer 190, detects the buffered amount of wire 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.

[0048] 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.

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

[0050] On the other hand, the voltage detection signal Vo is an actually measured 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.

[0051] 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. The current setting signal CCset corresponding to the set period or value is output to the current error amplifier (PWM) 34.

[0052] 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 amplified current error signal Ed.

[0053] 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.

[0054] The detachment detection unit 33 detects droplet detachment by, for example, comparing a value obtained by differentiating or second-order differentiating the voltage detection signal Vo after passing through an LPF with a predetermined detection threshold. The detection threshold 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 calculated from the voltage detection signal Vo and the current detection signal Io, which are actual measured values.

[0055] An average feed speed Favg of the welding wire 100 being fed is provided to waveform control table linear calculation unit 37. The average feed speed Favg is stored in advance in feed setting data unit 35. Note that, although feed setting data unit 35 is provided in welding power source 140 in this embodiment, various pieces of information related to feed settings may be stored in robot control device 120, and the various pieces of information may be output from robot control device 120 to welding power source 140.

[0056] Based on the given average feed speed Favg, the waveform control table linear calculation unit 37 determines values ​​such as the peak current Ip, the base current Ib, the time when the base current Ib starts, and the time when the base current Ib ends, and outputs these values ​​to the current setting unit 36. Note that, since the values ​​of the wire position phase, time, and cycle cyc can be converted into each other as described above, 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.

[0057] In this embodiment, the average feed speed Favg is input to waveform control table linear calculation unit 37, but a value related to the average feed speed Favg may be input as a set value to waveform control table linear calculation unit 37, and waveform control table linear calculation unit 37 may use the set value as the average feed speed Favg. For example, if a database of average feed speeds Favg and average current values ​​that enable optimal welding for that average feed speed Favg is stored in a storage unit (not shown), the average current value may be used as the set value, and the set value may be used as the average feed speed Favg.

[0058] In addition to the average feed speed Favg, the feed setting data unit 35 may store setting values ​​such as the wire amplitude Wf, the wire forward / reverse frequency Sf, the wire forward / reverse cycle Tf, the forward feed acceleration period ratio, and the reverse feed acceleration period ratio. Note that the wire amplitude Wf, the wire forward / reverse frequency Sf, and the wire forward / reverse cycle Tf may be determined based on the input average feed speed Favg. The feed setting data unit 35 may also store setting values ​​other than these as feed setting data.

[0059] In this embodiment, a period in which the feed rate is higher than the average feed rate Favg is defined as a forward feed period, and a period in which the feed rate is lower than the average feed rate Favg is defined as a reverse feed period, resulting in feed in which forward and reverse feed periods alternate (hereinafter abbreviated as "amplitude feed"). Note that a period in which the feed rate is lower than the average feed rate Favg refers to a rate less than the average feed rate Favg, and includes a negative feed rate, i.e., a rate at which the wire tip moves in the opposite direction from the position of the base material 200. The wire amplitude Wf ​​gives the range of change relative to the average feed rate Favg, and the wire forward / reverse cycle Tf gives the time period for change in the wire amplitude, which is the repetition unit. The wire forward / reverse frequency Sf is the reciprocal of the wire forward / reverse cycle Tf.

[0060] The average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle 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, the communication of these feed setting data is performed by CAN communication.

[0061] The average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle 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, the communication of these feed setting data is performed by CAN communication.

[0062] 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.

[0063] (Functional configuration of the robot control device) As described above, feed setting data such as average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle Tf are input to digital communication unit 122 of robot control device 120 via CAN communication from feed setting data unit 35 of welding power source 140. Robot control device 120 has digital communication unit 123 for outputting this feed setting data to digital communication unit 162 of servo amplifier 160. In this embodiment, digital communication unit 123 of robot control device 120 and digital communication unit 162 of servo amplifier 160 are connected via EtherCAT (registered trademark) communication.

[0064] (Servo amplifier functional configuration) Feed setting data such as average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle Tf are input via EtherCAT (registered trademark) communication to a digital communication unit 162 of the servo amplifier 160. A forward / reverse feed command generation unit 161 of the servo amplifier 160 (in FIG. 2, the forward / reverse feed command generation unit 161 is abbreviated to "feed command") generates a feed command for forward feed or reverse feed based on the setting information input via digital communication, i.e., the feed setting data.

[0065] The forward / reverse feed command generating unit 161 calculates the amplitude feed speed Ff, 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.

[0066] In this embodiment, the feeding speed command signal Fw is expressed by the following equation. Fw=Ff+Favg...Formula (A)

[0067] Furthermore, the forward / reverse feed command generation unit 161 may detect at which wire position phase of the amplitude feed the detachment occurred, based on the detachment detection signal DTR provided by the detachment detection unit 33. However, the feed speed command signal Fw expressed by equation (A) is generated only when the detachment of a droplet from the tip of the welding wire 100 is detected within an expected period. If the detachment of a droplet is not detected within the expected period, the forward / reverse feed command generation unit 161 may switch the feed speed command signal Fw to feed control at a constant speed. For example, the forward / reverse feed command generation unit 161 switches the feed speed command signal Fw to feeding at an average feed speed Favg. The switch from feeding at the average feed speed Favg to the feed control expressed by equation (A) is determined depending on the timing at which the detachment of a droplet is detected.

[0068] Based on the feed speed command signal Fw, servo amplifier 160 performs inverter control of servo motor 170. Furthermore, a synchronization signal generating unit 163 of servo amplifier 160 outputs a phase synchronization signal to welding power source 140. This phase synchronization signal is generated based on the feed speed command signal Fw.

[0069] Note that welding power source 140 and synchronization signal generator 163 of servo amplifier 160 may be connected at least via 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. By transmitting feeding setting data such as average feeding speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle Tf via digital communication, while transmitting the synchronization signal via analog communication, digital communication and analog communication can be used efficiently depending on the application.

[0070] 3 is a block diagram showing an example of the configuration of servo amplifier 160 and servo motor 170 including amplitude correction unit 164 in this embodiment. In this embodiment, amplitude correction unit 164 is included in servo amplifier 160, but this is not limited to this. For example, amplitude correction unit 164 may be included in welding power source 140 or robot control device 120, or the configuration of amplitude correction unit 164 may be included in welding system 50 as an independent control device.

[0071] The servo motor 170 includes a motor 61 and a motor encoder 62. The servo amplifier 160 includes an amplitude correction unit 164, a forward / reverse feed command generation unit 161, and a drive control unit 70. The amplitude correction unit 164 includes an actual amplitude detection unit 71 and a correction amount calculation unit 67. The actual amplitude detection unit 71 includes a forward / reverse determination unit 63, a reverse feed amplitude detection unit 641, a forward feed amplitude detection unit 642, a filter 651, a filter 652, and an averaging processing unit 66. The forward / reverse feed command generation unit 161 includes a forward / reverse speed command unit 68 and a speed command unit 69.

[0072] An actual feeding speed Vmon is measured from the motor 61 via a motor encoder 62. A forward / reverse determining unit 63 determines whether the amplitude is in a forward feeding period or a reverse feeding period according to the actual feeding speed Vmon.

[0073] The reverse feed amplitude detection unit 641 detects the amplitude of the reverse feed and outputs an actual reverse feed amplitude amount Ab. The forward feed amplitude detection unit 642 detects the amplitude of the forward feed and outputs an actual forward feed amplitude amount Af.

[0074] The backward transmission actual amplitude amount Ab and the forward transmission actual amplitude amount Af are filtered by the filters 651 and 652, and then averaged by the averaging processor 66, and the results are used as actual amplitude amounts.

[0075] The deviation E between the target amplitude amount At and the actual amplitude amount is input to a correction amount calculation unit 67. The correction amount calculation unit 67 includes a feedback controller. The feedback controller may be, for example, a PI controller, and FIG. 3 illustrates a PI controller. In the illustrated example, the correction amount calculation unit 67 performs PI control on the deviation and outputs an amplitude correction amount Au.

[0076] The forward / reverse speed command unit 68 calculates and outputs an amplitude feed speed Ff based on the amplitude correction amount Au.

[0077] The amplitude feed speed Ff and the average feed speed Favg are input to the speed command section 69. The speed command section 69 outputs a feed speed command signal Fw based on the amplitude feed speed Ff and the average feed speed Favg.

[0078] Based on the obtained feeding speed command signal Fw, the drive control unit 70 outputs an electric signal for controlling the driving of the motor 61 related to feeding control. Although the drive control unit 70 is not shown in Fig. 2, the drive control unit 70 outputs an electric signal based on the feeding speed command signal Fw to the servo motor 170 via the drive control unit 70.

[0079] FIG. 4 is a block diagram showing an example of the configuration of the servo amplifier 160 including the amplitude correction unit 164 and the servo motor 170 in this embodiment.

[0080] Of the control device shown in Fig. 4, detailed description of the same configuration as the control device shown in Fig. 3 will be omitted. In Fig. 4, the correction amount calculation unit 67 is divided into two, a forward feed period correction amount calculation unit 671 and a backward feed period correction amount calculation unit 672. Accordingly, averaging processing of the backward feed actual amplitude amount Ab and the forward feed actual amplitude amount Af becomes unnecessary. A deviation Ef based on the filtered forward feed actual amplitude amount Af and the target correction amount At is input to the forward feed period correction amount calculation unit 671. A deviation Eb based on the filtered backward feed actual amplitude amount Ab and the target correction amount At is input to the backward feed period correction amount calculation unit 672.

[0081] 3 in that the forward feed period correction amount calculation unit 671 and the backward feed period correction amount calculation unit 672 each perform feedback control such as PI control. The forward feed period correction amount calculation unit 671 outputs a forward feed amplitude correction amount Auf to the forward / reverse speed command unit 68. The backward feed period correction amount calculation unit 672 outputs a reverse feed amplitude correction amount Aub to the forward / reverse speed command unit 68.

[0082] The forward / reverse speed command unit 68 calculates and outputs an amplitude feed speed Ff based on the forward feed amplitude correction amount Auf and the reverse feed amplitude correction amount Aub. The amplitude feed speed Ff here may be a command that combines the amplitude command value in the forward feed period and the amplitude command value in the reverse feed period.

[0083] (Variation) Modified examples are described below. Note that the modified examples include multiple forms corresponding to Fig. 3, Fig. 4, etc., and therefore the addition of reference symbols is omitted. For example, the correction amount calculation unit in the following corresponds to the correction amount calculation unit 67 in Fig. 3, and the forward transmission period correction amount calculation unit 671 and the backward transmission period correction amount calculation unit 672 in Fig. 4.

[0084] The correction amount calculation unit calculates or measures at least the actual amplitude amount of the welding wire, or the error amount between the actual amplitude amount and the target amplitude amount. The actual amplitude amount here is the measured value of the difference (wave height) between the upper end position and the lower end position during one cycle, with the tip of the welding wire as the base point. The error amount may be calculated as follows: First, the average speed is subtracted from the feed speed. Then, the amount of change is calculated from the difference between the current waveform and a sample waveform prepared in advance, and the error amount is determined by integrating the amount of change. The correction amount calculation unit calculates the amplitude correction amount based on the actual amplitude amount or the error amount. The speed command unit calculates the amplitude command value based on the amplitude correction amount.

[0085] When the actual amplitude amount is calculated or measured, in the step of calculating the correction amount, the correction amount calculation unit calculates the correction amount (Au) based on the calculated or measured actual amplitude amount (Af, Ab) and the target amplitude amount (At: reference).

[0086] In the forward / reverse speed command unit, the amplitude command value is calculated by adding the amplitude correction amount Au and the target amplitude amount At.

[0087] The actual amplitude amount is at least one of the actual amplitude amount Af in the forward transport period, the actual amplitude amount Ab in the backward transport period, and the average actual amplitude amount Afb obtained by averaging the actual amplitude amounts in the forward transport period and the backward transport period.

[0088] The actual amplitude is calculated by detecting the actual feed speed of the welding wire and based on at least the detected actual feed speed and either the set average feed speed or the measured average feed speed.

[0089] The actual amplitude amount may be calculated by numerically integrating the actual wire feed speed according to a predetermined sample time and adding or subtracting a movement amount corresponding to the average wire feed speed to or from the integrated value for each predetermined wire forward / reverse cycle. The sample time may be a time determined based on, for example, the control cycle of the control device. For example, the sample time may be the control cycle time. The predetermined wire forward / reverse cycle may be, for example, a half cycle (1 / 2 cycle), but may also be any other cycle.

[0090] Fig. 5 is a diagram showing the relationships between various values ​​for the control device in this embodiment. In Fig. 5(a), the horizontal axis represents time (radian) and the vertical axis represents the speed of the tip of the welding wire. In Fig. 5(b), the horizontal axis represents time (radian) and the vertical axis represents the position of the tip of the welding wire. Note that the time (radian) on the horizontal axis represents the wire position phase described above.

[0091] 5(a), the feeding speed command signal Fw is expressed as Fw=Ff+Favg. In this case, the amplitude feeding speed Ff in the forward feeding period is given by the following equation: where t represents time.

[0092]

number

[0093] A uf is the forward feed amplitude correction amount. The amplitude feed speed Ff during the backward feed period is given by the following equation: where t represents time.

[0094]

number

[0095] A ubis the backward amplitude correction amount.

[0096] As shown in the figure, the actual feeding speed periodically deviates from the set average feeding speed (hereinafter also referred to as the "set average feeding speed"). The control cycle of the control device is generally shorter than the forward / reverse cycle.

[0097] The actual amplitude may be calculated as a value obtained by numerically integrating the value obtained by subtracting the set average feed rate from the actual feed rate of the welding wire in accordance with a predetermined sampling time. That is, the order of the integration calculation and the calculation of subtracting the set average feed rate may be reversed.

[0098] The actual amplitude amount may be calculated as an actual amplitude amount Af in the forward transmission period and an actual amplitude amount Ab in the backward transmission period.

[0099] There may be a step of averaging the calculated actual amplitude amount Af in the forward transmission period and the calculated actual amplitude amount Ab in the backward transmission period to calculate an average actual amplitude amount (see FIG. 3). In this case, in the step of calculating the amplitude correction amount Au, the amplitude correction amount Au is calculated based on the average actual amplitude amount and the target amplitude amount At.

[0100] In addition, in the step of calculating the correction amount, a forward feed amplitude correction amount Auf may be calculated based on at least the actual amplitude amount Af and the target amplitude amount At in the forward feed period. Similarly, a backward feed amplitude correction amount Aub may be calculated based on at least the actual amplitude amount Ab and the target amplitude amount At in the backward feed period (see FIG. 4).

[0101] (Actual amplitude detection section) The actual amplitude detection unit includes a means for detecting an actual feed speed of the welding wire. The actual amplitude detection unit includes a means for calculating an actual amplitude amount calculated based on at least the detected actual feed speed and either the set average feed speed value or the actual measured average feed speed value. For example, in the configuration of Fig. 3, the forward / reverse determination unit 63, the reverse feed amplitude detection unit 641, the forward feed amplitude detection unit 642, the filter 651, the filter 652, and the averaging processing unit 66 correspond to the actual amplitude detection unit referred to here.

[0102] (Correction amount calculation unit) The correction amount calculation unit includes a means for calculating an amplitude correction amount Au based on the actual amplitude amounts (forward transmission actual amplitude amount Af, backward transmission actual amplitude amount Ab) and the target amplitude amount At. The correction amount calculation unit also includes a means for calculating a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value (At+Au). For example, in the configuration of FIG. 3, the correction amount calculation unit 67 is included in the correction amount calculation unit referred to here.

[0103] In the above case, the actual amplitude amount calculated by the actual amplitude detection unit is at least one of the actual amplitude amount Af during the forward transmission period, the actual amplitude amount Ab during the reverse transmission period, and the average actual amplitude amount Afb obtained by averaging the actual amplitude amounts during the forward transmission period and the reverse transmission period.

[0104] The actual amplitude detection unit includes a backward transmission amplitude detection unit, a forward transmission amplitude detection unit, and an averaging processing unit (see FIG. 3). The backward transmission amplitude detection unit includes means for calculating the actual amplitude amount during the backward transmission period. The forward transmission amplitude detection unit includes means for calculating the actual amplitude amount during the forward transmission period. The averaging processing unit includes means for calculating the average actual amplitude amount from the actual amplitude amount during the backward transmission period and the actual amplitude amount during the forward transmission period.

[0105] In another embodiment, the actual amplitude detection unit includes a reverse feed amplitude detection unit and a forward feed amplitude detection unit (see FIG. 4). In this case, the correction amount calculation unit is composed of two units: a correction amount calculation unit for a forward feed period and a correction amount calculation unit for a reverse feed period. The reverse feed amplitude detection unit includes a means for calculating an actual amplitude amount for the reverse feed period. The forward feed amplitude detection unit includes a means for calculating an actual amplitude amount for the forward feed period. The correction amount calculation unit for the forward feed period includes a means for calculating a forward feed amplitude correction amount Auf for the forward feed period based on the actual amplitude amount Af for the forward feed period and the target amplitude amount At, and a means for calculating a value obtained by adding the forward feed amplitude correction amount Auf for the forward feed period and the target amplitude amount as an amplitude command value for the forward feed period. The correction amount calculation unit for the reverse feed period includes means for calculating a reverse feed amplitude correction amount Aub for the reverse feed period based on the actual amplitude amount Ab and the target amplitude amount At for the reverse feed period, and means for calculating a value obtained by adding the reverse feed amplitude correction amount Aub for the reverse feed period and the target amplitude amount as an amplitude command value for the reverse feed period.

[0106] (When calculating or measuring the amount of error) The above describes the case where the actual amplitude amount is calculated or measured. Next, the case where the error amount is calculated or measured will be described.

[0107] When the error amount is calculated or measured, the amplitude correction unit 164 includes at least an amplitude error amount calculation unit and a correction amount calculation unit. The amplitude error amount calculation unit may include at least some of the components included in the actual amplitude detection unit described above with reference to Figures 3 and 4. The correction amount calculation unit corresponds to the correction amount calculation unit described above with reference to Figures 3 and 4.

[0108] The amplitude error calculation unit includes a means for detecting an actual feed speed of the welding wire. The amplitude error calculation unit includes a means for calculating at least a difference between the detected actual feed speed and a reference target feed speed, and for calculating an amplitude error amount as a value obtained by numerically integrating the difference over a predetermined forward / reverse wire cycle. The correction amount calculation unit includes a means for calculating the amplitude error amount as an amplitude correction amount Au, and for calculating a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value (At+Au).

[0109] When calculating the error amount, first, the amplitude error amount calculation unit detects the actual feed speed of the welding wire. Next, the amplitude error amount calculation unit calculates the difference between the detected actual feed speed and a reference target feed speed. Then, the amplitude error amount calculation unit calculates the error amount by numerically integrating the difference amount over a predetermined number of forward and reverse wire cycles. Then, the correction amount calculation unit calculates the amplitude correction amount Au from the amplitude error amount.

[0110] Fig. 6 is a diagram showing the results of amplitude correction in this embodiment. Fig. 6 is composed of three graphs showing, from the top to the bottom, the actual feeding speed Vmon, the actual amplitude amount Afb, and the amplitude correction amount Au, and the horizontal axis of each graph represents time (ms). The target amplitude amount At is 5 mm, and amplitude correction starts at 100 ms.

[0111] In the initial state before amplitude correction begins, the actual amplitude Afb is approximately 4.4 mm. When amplitude correction begins at 100 ms, it can be seen that the amplitude correction amount Au increases. As a result, the wave height of the actual feed speed Vmon gradually increases, and as a result, the actual amplitude Afb approaches the target amplitude At, reaching 5 mm, which is the target amplitude At, at approximately 400 ms. After that, although there are some fluctuations, it can be seen that it stabilizes near the target amplitude At.

[0112] From this result, it can be confirmed that the actual amplitude amount Afb can be corrected to the target amplitude amount At by the amplitude correction method of this embodiment.

[0113] 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.

[0114] As described above, the present specification discloses the following:

[0115] (1) A feed control method for feeding a welding wire at a predetermined average wire feed speed while periodically repeating forward and reverse feed in accordance with a wire forward / reverse frequency, the forward feed period and the reverse feed period being one cycle, the method comprising: calculating or measuring at least an actual amplitude amount of the welding wire or an error amount between the actual amplitude amount and a target amplitude amount; calculating a correction amount based on the actual amplitude amount or the error amount; calculating an amplitude command value based on the correction amount; A feed control method comprising:

[0116] (2) When at least the actual amplitude amount is calculated or measured in the step of calculating or measuring the actual amplitude amount or the error amount, In the step of calculating the correction amount, the correction amount is calculated based on the calculated or measured actual amplitude amount and a target amplitude amount; In the step of calculating the amplitude command value, a value obtained by adding the correction amount and the target amplitude amount is calculated as the amplitude command value; The feed control method according to (1), characterized in that the actual amplitude amount uses at least one of the actual amplitude amount in the forward feed period, the actual amplitude amount in the reverse feed period, and the average actual amplitude amount obtained by averaging the actual amplitude amounts in the forward feed period and the reverse feed period.

[0117] (3) detecting an actual welding wire feed speed; The feed control method according to (2), characterized in that the actual amplitude amount is calculated based on at least the detected actual feed speed and a set average feed speed or an actual measured average feed speed.

[0118] (4) numerically integrating the actual feed rate of the welding wire according to a predetermined sampling time; The feed control method according to (3), characterized in that the actual amplitude amount is calculated by adding or subtracting a movement amount corresponding to an average wire feed speed to or from the integration result for each predetermined forward / reverse wire cycle.

[0119] (5) The feed control method according to (3), characterized in that the actual amplitude is calculated as a value obtained by subtracting an average feed speed from the actual feed speed of the welding wire in accordance with a predetermined sample time, and then integrating the resultant value over a predetermined forward / reverse wire cycle.

[0120] (6) The feeding control method according to any one of (1) to (5), characterized in that in the step of calculating the actual amplitude amount, the actual amplitude amount is calculated as an actual amplitude amount in the forward feeding period and an actual amplitude amount in the reverse feeding period.

[0121] (7) The method further includes a step of averaging the calculated actual amplitude amount Af in the forward transmission period and the calculated actual amplitude amount Ab in the backward transmission period to calculate an average actual amplitude amount, The feed control method according to (6), wherein in the step of calculating the correction amount, the correction amount is calculated based on the average actual amplitude amount and a target amplitude amount.

[0122] (8) The feeding control method according to (6), characterized in that in the step of calculating the correction amounts, at least a correction amount based on an actual amplitude amount and a target amplitude amount in the forward feeding period, and a correction amount based on an actual amplitude amount and a target amplitude amount in the reverse feeding period are calculated as the correction amounts.

[0123] (9) When at least the error amount is calculated in the step of calculating or measuring the actual amplitude amount or the error amount, Detect the actual feed speed of the welding wire, Calculating at least a difference between the detected actual feeding speed and a reference target feeding speed; The difference is numerically integrated over a predetermined number of forward and reverse cycles of the wire to calculate the error amount, The feed control method according to (1), wherein in the step of calculating the correction amount, the error amount is treated as the correction amount.

[0124] (10) A control device for controlling the feeding of a welding wire at a predetermined average wire feeding speed while periodically repeating forward and reverse feeding in accordance with a wire forward / reverse frequency, the forward feeding period and the reverse feeding period being one cycle, the control device includes at least an actual amplitude detection unit and a correction amount calculation unit, The real amplitude detection unit a means for detecting an actual feed speed of the welding wire; The measuring device includes a means for calculating an actual amplitude amount calculated based on at least the detected actual feed speed and either a set average feed speed value or an actual measured average feed speed value, The correction amount calculation unit means for calculating a correction amount based on the actual amplitude amount and the target amplitude amount; means for calculating a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value; The control device, characterized in that the actual amplitude amount calculated by the actual amplitude detection unit is at least one of the actual amplitude amount in a forward movement period, the actual amplitude amount in a reverse movement period, and an average actual amplitude amount obtained by averaging the actual amplitude amounts in the forward movement period and the reverse movement period.

[0125] (11) The actual amplitude detection unit includes a backward amplitude detection unit, a forward amplitude detection unit, and an averaging processing unit, the backward amplitude detection unit includes means for calculating an actual amplitude amount during a backward period; the normal transmission amplitude detection unit includes means for calculating an actual amplitude amount during a normal transmission period, The control device according to (10), wherein the averaging processing unit includes means for calculating an average actual amplitude amount from the actual amplitude amount in the backward transmission period and the actual amplitude amount in the forward transmission period.

[0126] (12) The actual amplitude detection unit includes a backward amplitude detection unit and a forward amplitude detection unit, the correction amount calculation unit is composed of two units: a correction amount calculation unit for a forward transport period and a correction amount calculation unit for a backward transport period; the backward amplitude detection unit includes means for calculating an actual amplitude amount during a backward period; the normal transmission amplitude detection unit includes means for calculating an actual amplitude amount during a normal transmission period, The correction amount calculation unit for the normal transport period a means for calculating a correction amount for the normal transport period based on the actual amplitude amount and the target amplitude amount for the normal transport period; a means for calculating a value obtained by adding the target amplitude amount to the correction amount in the normal feed period as an amplitude command value in the normal feed period, The backward movement period correction amount calculation unit a means for calculating a correction amount during the backward movement period based on the actual amplitude amount during the backward movement period and the target amplitude amount; a means for calculating a value obtained by adding the target amplitude amount to the correction amount during the backward transport period as an amplitude command value during the backward transport period; The control device according to (10) is characterized by:

[0127] (13) A control device for controlling the feeding of the welding wire at a predetermined average wire feeding speed while periodically repeating forward and reverse feeding in accordance with a wire forward / reverse frequency, the forward feeding period and the reverse feeding period being one cycle, the control device includes at least an amplitude error amount calculation unit and a correction amount calculation unit; The amplitude error amount calculation unit includes means for detecting an actual feed speed of a welding wire; at least a means for calculating a difference between the detected actual feed speed and a reference target feed speed, and for calculating an amplitude error amount as a value obtained by numerically integrating the difference over a predetermined forward / reverse wire cycle, the correction amount calculation unit includes means for calculating, as an amplitude command value, a value obtained by adding the amplitude error amount to a target amplitude amount as a correction amount; A control device comprising:

[0128] (14) A servo amplifier including the control device according to any one of (10) to (13).

[0129] (15) A welding system including the servo amplifier according to (14).

[0130] (16) A welding power source including the control device according to any one of (10) to (13).

[0131] (17) A welding system including the welding power source described in (16).

[0132] (18) A feed control program used to feed a welding wire at a predetermined average wire feed speed while periodically repeating forward and reverse feed in accordance with a wire forward / reverse frequency, the forward feed period and the reverse feed period being one cycle, comprising: The control device a function of calculating or measuring at least an actual amplitude amount of the welding wire or an error amount between the actual amplitude amount and a target amplitude amount; a function of calculating a correction amount based on the actual amplitude amount or the error amount; a function of calculating an amplitude command value based on the correction amount; A feed control program that realizes this. [Explanation of symbols]

[0133] 1 AC power supply 2 Primary rectifier 3 smoothing capacitors 4 Switching elements 5. Transformer 6 Secondary rectifier 7 Reactor 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 Section 50 Welding System 60 Control device 61 Motor 62 Motor Encoder 63 Forward / reverse determination section 641 Backward amplitude detector 642 Positive transmission amplitude detection unit 651 Filters 652 filters 66 Averaging processing section 67 Correction amount calculation section 671 Correction amount calculation unit for normal transmission period 672 Backward transmission period correction amount calculation unit 68 Forward / reverse speed command section 69 Speed ​​command section 70 Drive control unit 71 Real amplitude detection section 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 feed control method for feeding a welding wire at a predetermined average wire feed speed while periodically repeating forward and reverse feed in accordance with a wire forward / reverse frequency, the forward feed period and the reverse feed period being one cycle, comprising: calculating or measuring at least an actual amplitude amount of the welding wire or an error amount between the actual amplitude amount and a target amplitude amount; calculating a correction amount based on the actual amplitude amount or the error amount; calculating an amplitude command value based on the correction amount; A feed control method comprising:

2. When at least the actual amplitude amount is calculated or measured in the step of calculating or measuring the actual amplitude amount or the error amount, In the step of calculating the correction amount, the correction amount is calculated based on the calculated or measured actual amplitude amount and a target amplitude amount; In the step of calculating the amplitude command value, a value obtained by adding the correction amount and the target amplitude amount is calculated as the amplitude command value; 2. The feed control method according to claim 1, wherein the actual amplitude amount is at least one of an actual amplitude amount during a forward feed period, an actual amplitude amount during a reverse feed period, and an average actual amplitude amount obtained by averaging the actual amplitude amounts during the forward feed period and the reverse feed period.

3. Detect the actual feed speed of the welding wire, 3. The feed control method according to claim 2, wherein the actual amplitude is calculated based on at least the detected actual feed speed and a set average feed speed or an actual measured average feed speed.

4. Numerical integration of the actual feed speed of the welding wire according to a predetermined sample time; 4. The feed control method according to claim 3, wherein the actual amplitude is calculated by adding or subtracting a movement amount corresponding to an average wire feed speed to or from the integration result for each predetermined forward / reverse wire cycle.

5. 4. The feed control method according to claim 3, wherein the actual amplitude is calculated as a value obtained by subtracting an average feed speed from the actual feed speed of the welding wire in accordance with a predetermined sampling time and integrating the resultant value over a predetermined forward / reverse wire cycle.

6. 6. The feed control method according to claim 1, wherein in the step of calculating the actual amplitude amount, the actual amplitude amount is calculated as an actual amplitude amount in the forward feed period and an actual amplitude amount in the reverse feed period.

7. The method further includes a step of averaging the calculated actual amplitude amount Af in the forward transport period and the calculated actual amplitude amount Ab in the backward transport period to calculate an average actual amplitude amount, 7. The feed control method according to claim 6, wherein in the step of calculating the correction amount, the correction amount is calculated based on the average actual amplitude amount and a target amplitude amount.

8. 7. The feed control method according to claim 6, wherein in the step of calculating the correction amounts, at least a correction amount based on an actual amplitude amount and a target amplitude amount in the forward feed period, and a correction amount based on an actual amplitude amount and a target amplitude amount in the reverse feed period are calculated as the correction amounts.

9. When at least the error amount is calculated in the step of calculating or measuring the actual amplitude amount or the error amount, Detect the actual feed speed of the welding wire, Calculating at least a difference between the detected actual feeding speed and a reference target feeding speed; The difference is numerically integrated over a predetermined number of forward and reverse cycles of the wire to calculate the error amount, 2. The feed control method according to claim 1, wherein in the step of calculating the correction amount, the error amount is treated as the correction amount.

10. A control device for controlling the feeding of a welding wire at a predetermined average wire feeding speed while periodically repeating forward and reverse feeding in accordance with a wire forward / reverse frequency, the forward feeding period and the reverse feeding period being one cycle, the control device includes at least an actual amplitude detection unit and a correction amount calculation unit, The real amplitude detection unit a means for detecting an actual feed speed of the welding wire; The measuring device includes a means for calculating an actual amplitude amount calculated based on at least the detected actual feed speed and either a set average feed speed value or an actual measured average feed speed value, The correction amount calculation unit means for calculating a correction amount based on the actual amplitude amount and the target amplitude amount; means for calculating a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value; The control device, characterized in that the actual amplitude amount calculated by the actual amplitude detection unit is at least one of the actual amplitude amount in a forward movement period, the actual amplitude amount in a reverse movement period, and an average actual amplitude amount obtained by averaging the actual amplitude amounts in the forward movement period and the reverse movement period.

11. the actual amplitude detection unit includes a backward amplitude detection unit, a forward amplitude detection unit, and an averaging processing unit; the backward amplitude detection unit includes means for calculating an actual amplitude amount during a backward period; the normal transmission amplitude detection unit includes means for calculating an actual amplitude amount during a normal transmission period, 11. The control device according to claim 10, wherein the averaging processing unit includes means for calculating an average actual amplitude amount from the actual amplitude amount in the backward transmission period and the actual amplitude amount in the forward transmission period.

12. the actual amplitude detection unit includes a backward amplitude detection unit and a forward amplitude detection unit, the correction amount calculation unit is composed of two units: a correction amount calculation unit for a forward transport period and a correction amount calculation unit for a backward transport period; the backward amplitude detection unit includes means for calculating an actual amplitude amount during a backward period; the normal transmission amplitude detection unit includes means for calculating an actual amplitude amount during a normal transmission period, The correction amount calculation unit for the normal transport period a means for calculating a correction amount for the normal transport period based on the actual amplitude amount and the target amplitude amount for the normal transport period; a means for calculating a value obtained by adding the target amplitude amount to the correction amount in the normal feed period as an amplitude command value in the normal feed period, The backward movement period correction amount calculation unit a means for calculating a correction amount during the backward movement period based on the actual amplitude amount during the backward movement period and the target amplitude amount; a means for calculating a value obtained by adding the target amplitude amount to the correction amount during the backward transport period as an amplitude command value during the backward transport period; The control device according to claim 10, characterized in that

13. A control device for controlling the feeding of a welding wire at a predetermined average wire feeding speed while periodically repeating forward and reverse feeding in accordance with a wire forward / reverse frequency, the forward feeding period and the reverse feeding period being one cycle, the control device includes at least an amplitude error amount calculation unit and a correction amount calculation unit; The amplitude error amount calculation unit includes means for detecting an actual feed speed of a welding wire; at least a means for calculating a difference between the detected actual feed speed and a reference target feed speed, and for calculating an amplitude error amount as a value obtained by numerically integrating the difference over a predetermined forward / reverse wire cycle, the correction amount calculation unit includes means for calculating, as an amplitude command value, a value obtained by adding the amplitude error amount to a target amplitude amount as a correction amount; A control device comprising:

14. A servo amplifier comprising the control device according to any one of claims 10 to 13.

15. A welding system including the servo amplifier of claim 14.

16. A welding power supply comprising the control device according to any one of claims 10 to 13.

17. A welding system including the welding power supply of claim 16.

18. 1. A feed control program used to feed a welding wire at a predetermined average wire feed speed while periodically repeating forward and reverse feed in accordance with a wire forward / reverse frequency, the forward feed period and the reverse feed period being one cycle, The control device a function of calculating or measuring at least an actual amplitude amount of the welding wire or an error amount between the actual amplitude amount and a target amplitude amount; a function of calculating a correction amount based on the actual amplitude amount or the error amount; a function of calculating an amplitude command value based on the correction amount; A feed control program that realizes this.

Images