Feed control method, control device, welding power source, welding system, and recording medium

Abstract

The invention relates to a feed control method, a control device, a servo amplifier, a welding power source, a welding system, and a recording medium. A feed control method for feeding a welding wire at a predetermined average welding wire feed speed while periodically repeating forward feed and reverse feed on the basis of the forward and reverse frequencies of the welding wire at which a forward feed period and a reverse feed period are set as one cycle. The feed control method includes: calculating or actually measuring at least an actual amplitude of the welding wire or an error between the actual amplitude and a target amplitude; a step for calculating a correction amount on the basis of the actual amplitude amount or the error amount; and a step of calculating an amplitude command value on the basis of the correction amount. The purpose of the present invention is to suppress the deviation between a target amplitude amount and an actual amplitude amount, stabilize droplet detachment, reduce spatter, and improve welding quality in feed control that does not mainly include short-circuit transitions.

Description

TECHNICAL FIELD

[0001] The present application relates to a feeding control method, a control device, and a feeding control program, which feed a welding wire at a constant speed while periodically repeating a forward feeding period and a reverse feeding period. BACKGROUND

[0002] Conventionally, there is a control method of arc welding in which a leading end of a consumable electrode (hereinafter, referred to as "welding wire" or "welding electrode") is fed to a base material in accordance with periodic switching between a forward feeding period and a reverse feeding period. In this control method, it is known that control is performed so that a welding current is changed in accordance with a periodically changing welding wire leading end position, and a welding current lower than a predetermined current value is supplied during a period in which the leading end of the welding wire is reverse fed, whereby spatter reduction can be achieved. Such a technique is disclosed in, for example, Patent Literature 1.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2020-049506

[0006] Due to the influence of a welding wire feeding resistance load caused by clogging, bending, or the like of a conduit cable, or a motor load caused by assembly accuracy of a welding wire feeding device, there is a concern that an actual feeding speed at the time of forward feeding and reverse feeding is attenuated with respect to a set value. Due to this attenuation of the actual feeding speed, there is a possibility that a set condition and a measured value are deviated. In addition, the amount of deviation differs depending on the welding wire feeding resistance load or the motor load, and thus differs depending on the structure of the welding system.

[0007] As a condition in which the set value and the measured value are deviated due to the attenuation of the actual feeding speed, for example, a two-amplitude amount can be cited. The two-amplitude amount is a factor that is particularly important in feeding control that does not mainly use a short-circuit transfer. In a case where the measured value of the two-amplitude amount (hereinafter, also referred to as "actual amplitude amount") and the set value (hereinafter, also referred to as "target amplitude amount") are different, droplet detachment becomes unstable. In other words, spatter in welding increases.

[0008] In addition, in a case where the target amplitude amount and the actual amplitude amount are different, the welding wire moving amount in the feeding direction to one side increases, and thus the average feeding speed also does not coincide with the set value. In other words, there is also a problem that a desired deposition amount cannot be obtained, and an adverse effect on the welding quality is also caused.

[0009] However, in Patent Literature 1, the influence of the welding wire feeding resistance load, the motor load, and the problem in a case where the target amplitude amount and the actual amplitude amount are different due to the influence are not considered. SUMMARY

[0010] An object of the present application is to suppress a deviation between a target amplitude amount and an actual amplitude amount in a feeding control that does not mainly use short-circuit transition, stabilize a droplet detachment, and achieve a reduction in spatter and an improvement in welding quality.

[0011] The present application is configured by the following structure.

[0012] (1) A feeding control method of periodically repeating a forward feeding and a reverse feeding of a welding wire according to a welding wire forward-reverse frequency that sets a forward feeding period and a reverse feeding period as one cycle, while feeding the welding wire at a predetermined average welding wire feeding speed, characterized by,

[0013] a step of at least calculating or actually measuring an actual amplitude amount of the welding wire or an error amount of the actual amplitude amount from a target amplitude amount;

[0014] a step of calculating a correction amount based on the actual amplitude amount or the error amount; and

[0015] a step of calculating an amplitude command value based on the correction amount.

[0016] (2) A control device of periodically repeating a forward feeding and a reverse feeding of a welding wire according to a welding wire forward-reverse frequency that sets a forward feeding period and a reverse feeding period as one cycle, while feeding controlling the welding wire at a predetermined average welding wire feeding speed, characterized by,

[0017] the control device at least has an actual amplitude detection section and a correction amount calculation section,

[0018] the actual amplitude detection section includes:

[0019] a unit that detects an actual feeding speed of the welding wire; and

[0020] a unit that at least calculates an actual amplitude amount that is calculated based on any one of a detected actual feeding speed and an average feeding speed set value and an average feeding speed actually measured value,

[0021] the correction amount calculation section includes:

[0022] a unit that calculates a correction amount based on the actual amplitude amount and a target amplitude amount; and

[0023] a unit that calculates a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value,

[0024] The actual amplitude quantity calculated in the actual amplitude detection section is at least one of an actual amplitude quantity during forward feeding, an actual amplitude quantity during reverse feeding, and an average actual amplitude quantity obtained by averaging actual amplitude quantities during forward feeding and reverse feeding.

[0025] (3) A control device that feeds a welding wire periodically repeating forward feeding and reverse feeding according to a welding wire forward-reverse frequency in which a forward feeding period and a reverse feeding period are set as one cycle, while feeding the welding wire at a predetermined average welding wire feeding speed, characterized by

[0026] The control device has at least an amplitude error quantity calculation section and a correction quantity calculation section,

[0027] The amplitude error quantity calculation section includes:

[0028] a unit that detects an actual feeding speed of the welding wire; and

[0029] a unit that calculates at least a difference quantity between the detected actual feeding speed and a target feeding speed serving as a reference, and calculates an amplitude error quantity as a value obtained by numerically integrating the difference quantity over a predetermined welding wire forward-reverse cycle,

[0030] The correction quantity calculation section includes a unit that adds the amplitude error quantity to a target amplitude quantity and calculates a value after the addition as an amplitude command value.

[0031] (4) A feeding control program used for feeding a welding wire periodically repeating forward feeding and reverse feeding according to a welding wire forward-reverse frequency in which a forward feeding period and a reverse feeding period are set as one cycle, while feeding the welding wire at a predetermined average welding wire feeding speed,

[0032] to cause a control device to function as:

[0033] a function of calculating at least or actually measuring an actual amplitude quantity of the welding wire or an error quantity of the actual amplitude quantity from a target amplitude quantity;

[0034] a function of calculating a correction quantity based on the actual amplitude quantity or the error quantity; and

[0035] a function of calculating an amplitude command value based on the correction quantity.

[0036] According to the present application, in feeding control that is not mainly based on short-circuiting transfer, a deviation of a target amplitude quantity from an actual amplitude quantity can be suppressed, so that droplet detachment is stabilized, and reduction of spatter and improvement of welding quality can be achieved.

[0037] Further, since the actual amplitude amount is calculated on the basis of the set average speed, if the actual amplitude amounts during the forward feeding and the reverse feeding are identical, the actual average speed is equal to the set average speed, and the present application also functions as correction of the average speed. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a diagram showing a schematic configuration of a welding system to which the present embodiment is applied.

[0039] Figure 2 is a block diagram showing a schematic configuration of a welding power source, a robot control device, and control of a servo amplifier in the present embodiment.

[0040] Figure 3 is a block diagram showing a configuration example of a servo amplifier including an amplitude correction section and a servo motor in the present embodiment.

[0041] Figure 4 is a block diagram showing a configuration example of a servo amplifier including an amplitude correction section and a servo motor in the present embodiment.

[0042] Figure 5 is a diagram showing a relationship of various values of a control device in the present embodiment.

[0043] Figure 6 is a diagram showing a result of amplitude correction in the present embodiment.

[0044] -Explanation of Reference Numerals-

[0045] 1 AC power source

[0046] 2 Primary side rectifier

[0047] 3 Smoothing capacitor

[0048] 4 Switching element

[0049] 5 Transformer

[0050] 6 Secondary side rectifier

[0051] 7 Reactor

[0052] 30 Inverter drive section

[0053] 31 Current detection section

[0054] 32 Voltage detection section

[0055] 33 Disengagement detection section

[0056] 34 Current error amplification section

[0057] 35 Feed set data section

[0058] 36 current setting section

[0059] 36A target current setting section

[0060] 36B welding wire tip position conversion section

[0061] 36C voltage setting section

[0062] 37 waveform control table linear operation section

[0063] 38 phase delay correction section

[0064] 39 push-type wire feeder control section

[0065] 40 A / D input section

[0066] 41 electrical angle adjustment section

[0067] 42 digital communication section

[0068] 43 welding timing section

[0069] 50 welding system

[0070] 60 control device

[0071] 61 motor

[0072] 62 motor encoder

[0073] 63 forward / reverse determination section

[0074] 641 reverse feed amplitude detection section

[0075] 642 forward feed amplitude detection section

[0076] 651 filter

[0077] 652 filter

[0078] 66 averaging processing section

[0079] 67 correction amount calculation section

[0080] 671 forward feed period correction amount calculation section

[0081] 672 reverse feed period correction amount calculation section

[0082] 68 forward / reverse speed command section

[0083] 69 speed command section

[0084] 70 drive control section

[0085] 71 actual amplitude detection section

[0086] 100 welding wire

[0087] 110 welding robot

[0088] 111 welding torch

[0089] 120 robot control device

[0090] 122 digital communication section

[0091] 123 digital communication section

[0092] 140 welding power source

[0093] 141 control system section

[0094] 150 controller

[0095] 160 servo amplifier

[0096] 161 forward / reverse feed command generation section

[0097] 162 digital communication section

[0098] 163 synchronization signal generation section

[0099] 170 servo motor

[0100] 180 push-in motor

[0101] 190 welding wire buffer

[0102] 191 string mode conversion section

[0103] 200 workpiece DETAILED DESCRIPTION

[0104] Hereinafter, an embodiment of the present application will be described in detail with reference to the drawings.

[0105] Further, in the present embodiment, 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 structure of the present embodiment.

[0106] Figure 1 is a schematic diagram showing the structure of a welding system according to the present embodiment. The welding system 50 is provided with a welding robot (ROBOT) 110, a robot control device 120, a welding power source 140, a controller 150, a servo amplifier 160, a servo motor 170, a push-in motor 180, and a welding wire buffer 190. The servo motor 170 and the push-in motor 180 feed the welding wire 100.

[0107] The welding power source 140 is connected to the welding robot 110 via a positive power cable to be electrically connected to the welding wire 100 as a consumable electrode, and is connected to the workpiece (hereinafter also referred to as "base material") 200 via a negative power cable. This connection is in the case of welding in opposite polarity. In the case of welding in positive polarity, the welding power source 140 can be reversed in polarity.

[0108] Further, the welding power source 140 is connected to the push-in motor 180 via a signal line, and can control the feeding speed of the welding wire.

[0109] The welding robot 110 has a welding torch 111 as an end effector. The welding torch 111 has an electrode mechanism that electrically connects the welding wire 100, that is, a welding tip. The welding wire 100 generates an arc from the tip by being electrically connected from the welding tip, and uses the heat to weld the workpiece 200 as a welding object. In addition, the welding tip is also sometimes referred to as a contact tip.

[0110] The welding torch 111 has a shielding gas nozzle that becomes a mechanism for ejecting shielding gas. The shielding gas is supplied from a not-illustrated shielding gas supply device.

[0111] The servo motor 170 is provided near the welding torch 111. A servo amplifier 160 connected to the servo motor 170 controls the servo motor 170. In the present embodiment, the welding torch 111 is provided as a structure independent of the servo motor 170, but can also be a welding torch having a structure in which the servo motor 170 is provided in the welding torch 111. The servo motor 170 switches the direction of rotation based on a forward / reverse feed command, and performs feed control. Further, the servo amplifier 160 can perform high-speed arithmetic processing, and has a forward / reverse feed command generation section 161 as described later.

[0112] A welding wire buffer 190 is disposed between the servo motor 170 and the push-in motor 180. The servo motor 170 feeds the welding wire 100 in the forward and reverse directions, and the push-in motor 180 feeds the welding wire 100 only in the forward direction, so that the feed directions of the servo motor 170 and the push-in motor 180 are sometimes different. Therefore, a situation in which a large load is easily applied to the welding wire 100 occurs in the feed path. In order to be able to appropriately perform feed control also in such a feed situation, the welding wire buffer 190 is provided to suppress the buckling of the welding wire, and the like.

[0113] The welding wire 100 used in the present embodiment is not particularly limited. For example, either of a solid wire without flux and a flux-cored wire including flux can be used. Further, the material of the welding wire 100 is not limited. For example, the material can be mild steel, can be stainless steel, aluminum, titanium, or can have a plating layer such as Cu on the surface of the welding wire. The diameter of the welding wire 100 is also not particularly limited. In the case of the present embodiment, it is preferable to set the upper limit of the diameter to 1.6 mm and the lower limit to 0.8 mm.

[0114] In the present embodiment, the specific structure of the workpiece 200 is not particularly limited, and the welding conditions such as the joint shape, the welding posture, the groove shape, and the like are not particularly limited. The robot control device 120 mainly controls the action of the welding robot 110. Therefore, the robot control device 120 can also be said to be a robot controller. The robot control device 120 holds, in advance, a teaching mode that determines the action mode of the welding robot 110, the welding start position, the welding end position, the welding conditions, the swing action, and the like, instructs them to the welding robot 110, and controls the action of the welding robot 110. Further, the robot control device 120 provides the welding conditions such as the welding current, the welding voltage, the feed speed, and the like in the welding work to the welding power source 140 in accordance with the teaching data.

[0115] In addition, as shown in Figure 1 the present embodiment, the welding system 50 is provided in a structure in which the robot control device 120 and the welding power source 140 are independent, but can also be provided in a structure in which the robot control device 120 is provided in the welding power source 140. The controller 150 is connected to the robot control device 120 and performs creation or display of a program for causing the welding robot 110 to act, input of teaching data, and the like. The information input by the user to the controller 150 is provided to the robot control device 120. Further, the controller 150 can also have a function of performing manual operation of the welding robot 110. The connection between the controller 150 and the robot control device 120 is not particularly limited in terms of the kind of wire or wireless.

[0116] The welding power source 140 supplies electric power to the welding wire 100 and the workpiece 200 in accordance with the instruction from the robot control device 120, and thereby generates an arc between the welding wire 100 and the workpiece 200. Further, the welding power source 140 outputs a control signal of the push-in motor 180 in accordance with the instruction from the robot control device 120.

[0117] Next, the functional structure of the welding system 50 related to the present embodiment will be described in detail. Figure 2 Next, the functional structure of the welding system 50 related to the present embodiment will be described in detail. Figure 2 is a block diagram that shows the outline structure related to the control of the welding power source 140, the robot control device 120, and the servo amplifier 160 in the present embodiment.

[0118] The welding power source 140 is connected to the robot control device 120 through digital communication, and the robot control device 120 is connected to the servo amplifier 160 through digital communication. That is, in the order of the servo amplifier 160, the robot control device 120, and the welding power source 140 connected through digital communication, they are connected in a linear fashion. This can be interpreted as a state in which the servo amplifier 160 and the welding power source 140 are indirectly connected through digital communication. Alternatively, the servo amplifier 160, the welding power source 140, and the robot control device 120 can be connected in a linear fashion in this order. This can be interpreted as a state in which the servo amplifier 160 and the welding power source 140 are directly connected through digital communication.

[0119] Further, in the present embodiment, the welding power source 140 and the robot control device 120 communicate through CAN (Controller Area Network), which is one of field networks for industry, and the robot control device 120 and the servo amplifier 160 communicate through EtherCAT (Ethernet for Control Automation Technology) (registered trademark), which is one of field networks for industry, but are not limited thereto.

[0120] (Functional configuration of welding power source)

[0121] The control system section 141 of the welding power source 140 is executed by, for example, the robot control device 120 or a computer not shown, executing a program. The control system section 141 corresponds to a setting section that sets values capable of deriving a forward feed acceleration period described later, values capable of deriving a forward feed deceleration period, values capable of deriving a reverse feed acceleration period, and values capable of deriving a reverse feed deceleration period. The input method of the values in the setting is not particularly limited. For example, the setting can be performed by a user inputting values. There can be a database, table data, or the like in which the set values are stored, and the values are extracted from the database, table data, or the like to perform the setting. The values can be set according to various conditions such as frequency conditions. The set values can be fixed values, or values that vary depending on certain detected values obtained in welding.

[0122] The control system section 141 of the welding power source 140 includes a current setting section 36. The current setting section 36 in the present embodiment has a function of setting various current values that regulate the welding current that flows through the welding wire 100. The current setting section 36 has a function of setting the time at which each period of the current control starts and the time at which each period ends. The current setting section 36 has a target current setting section 36A, a welding wire tip position conversion section 36B, and a voltage setting section 36C. The target current setting section 36A has a function of setting the start time and the end time of each period for the peak period Dap, the falling period Ddwn, the base period Db, and the rising period Dup involved in the current control. The welding wire tip position conversion section 36B has a function of obtaining information of the tip position of the welding wire 100.

[0123] In addition, the various condition settings can be determined, for example, based on a setting value that is input by an operator in advance, a waveform control table prepared in advance, a database of welding conditions, or the like. The setting value, the table, the database, or the like can be stored in any of the structural elements of the welding system 50. The setting value, the table, the database, or the like can be stored, for example, in the robot control device 120, the welding power source 140, or the like.

[0124] The various condition settings for each period of the peak period Dap, the falling period Ddwn, the base period Db, and the rising period Dup involved in the high current period TIP (the sum of the Dup and Dap periods in the present embodiment) and the low current period TIB (the sum of the Ddwn and Db periods in the present embodiment) can be determined by the waveform control table linear operation section 37 based on a waveform control table prepared in advance. In addition, the various condition settings referred to herein refer to condition settings such as current values, times, or phases in the present embodiment.

[0125] The welding current represents a pulse waveform of the welding current in which the high current period TIP and the low current period TIB are alternately repeated based on the phase involved in the welding wire tip position (hereinafter referred to as "welding wire position phase" or "position phase"). In the present embodiment, the timing of the peak period Dap, the falling period Ddwn, the base period Db, and the rising period Dup is controlled based on the welding wire position phase of 0 to 360° (0 to 2π) in which the case where the welding wire tip position is closest to the nozzle side is set to 0° and the case where the welding wire tip position is closest to the base material side is set to 180°. In addition, the above-described welding wire position phase can also be expressed as a case where the welding wire position phase is 0° with the welding wire tip position at the time of switching from the reverse feeding period to the forward feeding period as a reference.

[0126] Based on the set value of the average feeding speed Favg in the welding condition information held by the control system part 141, in the current setting part 36, the set current value Iap of the peak period Dap in the high current period TIP calculated by the waveform control table linear operation part 37 (hereinafter, also referred to as "peak current Iap") and the set current value Ib of the base period Db in the low current period TIB (hereinafter, also referred to as "base current Ib") are set.

[0127] In the case of the present embodiment, the welding current is basically controlled by both of the peak current Iap and the base current Ib. Therefore, the start time of the low current period TIB can also be expressed as the low current start time, which is the time of the transition to the base current Ib, that is, the start time of the falling period Ddwn. Further, the time of the end of the low current period TIB can also be expressed as the base current Ib end time, that is, the low current end time. The period (time) of the falling period Ddwn involved in the time of the start of the low current period TIB and the time of the end of the low current period TIB is calculated in the waveform control table linear operation part 37. The start time of the high current period TIP, that is, the start time of the rising period Dup can be expressed as the high current start time, and the time of the end of the high current period TIP can also be expressed as the high current end time.

[0128] In addition, the above-described various start times, end times, and the like are described based on time. However, the value of the wire position phase can also be used as a reference, and the value can be converted into time or the period cyc according to the wire position phase. That is, the values of the wire position phase, time, and the period cyc can be converted into each other, and therefore, control can also be performed based on any of the values as a reference.

[0129] Further, based on the phase synchronization signal and the phase delay correction amount signal from the servo amplifier 160, the wire tip position conversion part 36B determines the wire tip position. In the present embodiment, the wire tip position can be expressed using an angle (0 to 2π) as the wire position phase.

[0130] The phase delay correction amount signal is output from the phase delay correction part 38. The phase delay correction part 38 has a database, which is omitted from the illustration. In the database, for various welding conditions, data in which the difference between the set information having periodicity and the actual forward / reverse feeding operation of the servo motor 170 is calculated in advance is stored. For example, in the case where the welding condition is the wire forward / reverse frequency, based on the above-described database, the phase delay correction amount is determined according to the value of the used wire forward / reverse frequency, and is output from the phase delay correction part 38 as the phase delay correction amount signal.

[0131] The power supply main circuit of the welding power source 140 is composed of a three-phase alternating current power source (hereinafter, also referred to as "AC power source") 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.

[0132] The alternating current power input from the AC power source 1 is full-wave rectified by the primary-side rectifier 2, and is further smoothed by the smoothing capacitor 3 to be converted into direct current power. Next, the direct current power is converted into high-frequency alternating current power by inverter control by the switching element 4, and is converted into secondary-side power via the transformer 5. The alternating current output of the transformer 5 is full-wave rectified by the secondary-side rectifier 6, and is further smoothed by the reactor 7. The output current of the reactor 7 is supplied as an output from the power supply main circuit to the contact tip to be supplied to the welding wire 100 as a consumable electrode.

[0133] The welding wire 100 is fed by the push-type motor 180 and the servo motor 170 to generate an arc between the welding wire 100 and the base material 200. A forward feeding period in which the leading end of the welding wire 100 is moved toward the base material 200 is denoted as a forward feeding period TP. A reverse feeding period in which the leading end of the welding wire 100 is moved in a direction opposite to the direction in which the base material 200 is present is denoted as a reverse feeding period TN. In the case of the present embodiment, the feeding motor periodically feeds the welding wire 100 by combining the forward feeding period TP and the reverse feeding period TN as one cycle. In addition, the leading end of the welding wire generally refers to the leading end of the welding wire, ignoring the presence of a droplet hanging from the leading end of the welding wire. That is, it is considered that the welding wire immediately transferred to the base material 200 by the arc.

[0134] The feeding of the welding wire 100 by the push-type motor 180 is controlled by a control signal based on the push-type wire feeder control section 39. In addition, the average value of the feeding speed is substantially the same as the melting speed. In the case of the present embodiment, the feeding of the welding wire 100 by the push-type motor 180 is also controlled by the welding power source 140.

[0135] Further, the push-type wire feeder control section 39 controls in accordance with the state of the welding wire buffer 190. In the present embodiment, the welding wire buffer 190 is provided with a play portion of the welding wire (i.e., a gap portion that retreats in the case where the welding wire is slackened due to the influence of the feeding between the motors) in order not to apply a large load to the welding wire in the feeding path between the push-type motor 180 and the servo motor 170, and the amount of buffering of the welding wire is detected as a rotation angle by a sensor, i.e., an absolute encoder, built into the welding wire buffer 190. The detected value is converted into an analog signal by a serial-to-digital conversion section 191, and an electrical angle is calculated by an electrical angle calculation section. The calculated electrical angle is input to the A / D input section 40 of the welding power source.

[0136] A difference signal that takes the difference between the electrical angle from the A / D input section 40 and the reference value of the electrical angle that is set in advance in the electrical angle adjustment section 41 is input to the push-type wire feeder control section 39. The push-type wire feeder control section 39 controls the push-type motor 180 based on the difference signal so that the amount of buffer of the welding wire becomes appropriate, thereby performing disturbance control that does not apply a large load to the feeding system. Note that, in the present embodiment, the aforementioned disturbance control is performed, but the present embodiment is not limited thereto. Furthermore, in the present embodiment, an absolute encoder that is built into the welding wire buffer 190 is used, but the present embodiment is not limited thereto. For example, a rotation angle sensor can be used, in which case the string mode conversion section 191 can not be provided.

[0137] A voltage setting signal Vap that is a target value of the voltage applied between the welding tip and the base material 200 is supplied from the voltage setting section 36C to the current setting section 36.

[0138] On the other hand, the voltage detection signal Vo is a measured value. In the present embodiment, the voltage detection signal Vo is input to the current setting section 36 through a low-pass filter LPF, along with the disengagement detection signal DTR described later, via the disengagement detection section 33 described later. Note that, the present embodiment can be configured so that a voltage comparison section is provided, and the difference between the voltage setting signal Vap and the voltage detection signal Vo is amplified as a voltage error amplification signal and output to the current setting section 36.

[0139] The current setting section 36 controls the welding current during the peak period Dap so that the length of the arc (hereinafter, also referred to as "arc length") becomes fixed. The current setting section 36 determines at least the peak period, the rise period, the base period, and the rise period based on the voltage setting signal Vap and the voltage detection signal Vo, and performs setting. Note that, the value of the peak current Ip and the value of the base current Ib can be set again. A current setting signal CCset corresponding to the set period or value is output to the current error amplification section (PWM) 34.

[0140] The current error amplification section 34 amplifies the difference between the current setting signal CCset that is supplied as a target value and the current detection signal Io that is detected by the current detection section 31, and outputs the amplified signal as a current error amplification signal Ed to the inverter drive section 30. The inverter drive section 30 corrects the drive signal Ec of the switching element 4 based on the current error amplification signal Ed.

[0141] A disengagement detection signal DTR that becomes a signal that detects disengagement of the droplet from the front end of the welding wire 100 is also input to the current setting section 36. The disengagement detection signal DTR is output from the disengagement detection section 33. The disengagement detection section 33 monitors the change in the voltage detection signal Vo output from the voltage detection section 32, and detects disengagement of the droplet from the welding wire 100 based on the change. Note that, the disengagement detection section 33 is an example of a detection unit.

[0142] The detachment detection section 33 detects detachment of the droplet, for example, by comparing a value obtained by differentiating or second-order differentiating the voltage detection signal Vo that has passed through the LPF with a given threshold value for detection. The threshold value for detection is stored in advance in an omitted storage section. Alternatively, the detachment detection section 33 can generate a detachment detection signal DTR based on a change in the resistance value calculated from the voltage detection signal Vo and the current detection signal Io as measured values.

[0143] The average wire feed speed Favg is supplied to the waveform control table linear operation section 37. The average wire feed speed Favg is stored in advance in the wire feed setting data section 35. Alternatively, the wire feed setting data section 35 can store various information relating to wire feed setting in advance in the robot control device 120, and output the various information from the robot control device 120 to the welding power source 140.

[0144] The waveform control table linear operation section 37 determines the values of the peak current Ip, the base current Ib, the time at which the base current Ib starts, the time at which the base current Ib ends, and the like based on the supplied average wire feed speed Favg, and outputs the values to the current setting section 36. Alternatively, as described above, the values of the wire position phase, the time, and the period cyc can be converted into each other, and thus the set value of the phase at which the base starts and the like can be converted into the value of the time or the period cyc, and the converted value can be output to the current setting section 36.

[0145] In the present embodiment, the average wire feed speed Favg is input to the waveform control table linear operation section 37, but a value related to the average wire feed speed Favg can be input to the waveform control table linear operation section 37 as a set value, and the waveform control table linear operation section 37 can use the set value by replacing the average wire feed speed Favg. For example, in a case where a database of the average wire feed speed Favg and the average current value at which optimal welding can be performed with respect to the average wire feed speed Favg is stored in an omitted storage section, the average current value can be used as the set value, and the set value can be used by replacing the average wire feed speed Favg.

[0146] The wire feed setting data section 35 can store the set values of the wire amplitude Wf, the wire forward / reverse frequency Sf, and the wire forward / reverse period Tf, the forward wire feed acceleration period ratio, the reverse wire feed acceleration period ratio, and the like in addition to the average wire feed speed Favg. Alternatively, the wire amplitude Wf, the wire forward / reverse frequency Sf, and the wire forward / reverse period Tf can be determined based on the input average wire feed speed Favg. Furthermore, the wire feed setting data section 35 can store set values other than these as wire feed setting data.

[0147] In the present embodiment, a period in which the feeding speed is higher than the average feeding speed Favg is set as a forward feeding period, a period in which the feeding speed is lower than the average feeding speed Favg is set as a reverse feeding period, and a feeding in which the forward feeding period and the reverse feeding period appear alternately is performed (hereinafter, referred to as "amplitude feeding" is omitted). In addition, the period in which the feeding speed is lower than the average feeding speed Favg means lower than the average feeding speed Favg, and includes a negative feeding speed, that is, a speed at which the tip of the welding wire moves to a surface opposite to the position at which the base material 200 is present. The welding wire amplitude Wf provides a variation amplitude with respect to the average feeding speed Favg, and the welding wire forward-reverse period Tf provides a time of variation of the welding wire amplitude as a unit of repetition. The welding wire forward-reverse frequency Sf is an inverse of the welding wire forward-reverse period Tf.

[0148] The average feeding speed Favg, the welding wire amplitude Wf, the welding wire forward-reverse frequency Sf, and the welding wire forward-reverse period Tf stored in the feeding setting data section 35 are input from the digital communication section 42 to the digital communication section 122 of the robot control device 120. In the present embodiment, communication of these feeding setting data is performed by CAN communication.

[0149] The average feeding speed Favg, the welding wire amplitude Wf, the welding wire forward-reverse frequency Sf, and the welding wire forward-reverse period Tf stored in the feeding setting data section 35 are input from the digital communication section 42 to the digital communication section 122 of the robot control device 120. In the present embodiment, communication of these feeding setting data is performed by CAN communication.

[0150] The welding timing section 43 processes each task in the order of idle, gas flow, arc striking, welding, and anti-wire sticking on the basis of the teaching data. In addition, in the welding power source 140, the welding condition information possessed by the robot control device 120 is also indicated by a dashed line in the welding timing section 43. Figure 2 In the welding power source 140, the welding condition information possessed by the robot control device 120 is also indicated by a dashed line in the welding timing section 43.

[0151] (Functional structure of robot control device)

[0152] As described above, the average feeding speed Favg, the welding wire amplitude Wf, the welding wire forward-reverse frequency Sf, the welding wire forward-reverse period Tf, and the like are input from the feeding setting data section 35 of the welding power source 140 to the digital communication section 122 of the robot control device 120 by CAN communication. The robot control device 120 has a digital communication section 123 for outputting these feeding setting data to the digital communication section 162 of the servo amplifier 160. In the present embodiment, the digital communication section 123 of the robot control device 120 and the digital communication section 162 of the servo amplifier 160 are connected by EtherCAT (registered trademark) communication.

[0153] (Functional structure of servo amplifier)

[0154] The average feeding speed Favg, the wire amplitude Wf, the wire forward / reverse frequency Sf, the wire forward / reverse period Tf, and the like are input to the digital communication unit 162 of the servo amplifier 160 through EtherCAT (registered trademark) communication. The forward / reverse feeding command generation unit 161 (hereinafter, the forward / reverse feeding command generation unit 161 is simply referred to as a feeding command) of the servo amplifier 160 generates a feeding command of forward feeding or reverse feeding based on the setting information input through the digital communication, that is, the feeding setting data. Figure 2

[0155] The forward / reverse feeding command generation unit 161 calculates the amplitude feeding speed Ff and outputs a feeding speed command signal Fw to the servo motor 170 based on the amplitude feeding speed Ff and the average feeding speed Favg.

[0156] In the case of the present embodiment, the feeding speed command signal Fw is represented by the following equation.

[0157] Fw = Ff + Favg ··· Equation (A)

[0158] Further, the forward / reverse feeding command generation unit 161 can also detect at which wire position phase the detachment occurs by the detachment detection signal DTR supplied from the detachment detection unit 33. However, the feeding speed command signal Fw represented by Equation (A) is limited to a case where the detachment is detected during a period in which the droplet is supposed to detach from the front end of the wire 100. In a case where the detachment of the droplet is not detected during the supposed period, the forward / reverse feeding command generation unit 161 can also switch the feeding speed command signal Fw to feeding control based on a constant speed. For example, the forward / reverse feeding command generation unit 161 switches the feeding speed command signal Fw to feeding based on the average feeding speed Favg. The switching from the feeding based on the average feeding speed Favg to the feeding control represented by Equation (A) is determined in accordance with the timing at which the detachment of the droplet is detected.

[0159] The servo amplifier 160 performs inverter control of the servo motor 170 based on the feeding speed command signal Fw. Further, the synchronization signal generation unit 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 feeding speed command signal Fw.

[0160] ​Further, the welding power source 140 and the synchronization signal generation section 163 of the servo amplifier 160 can be connected at least through analog input and output. In this case, the synchronization signal is input from the servo amplifier 160 to the welding power source 140 via the analog input and output. The average feed speed Favg, the welding wire amplitude Wf, the welding wire forward / reverse frequency Sf, the welding wire forward / reverse period Tf, and the like are transmitted by digital communication, and on the other hand, the synchronization signal is transmitted by analog communication, whereby it is possible to efficiently separate the use of digital communication and analog communication according to the use.

[0161] Figure 3 is a block diagram showing a configuration example of the servo amplifier 160 including the amplitude correction section 164 in the embodiment and the servo motor 170. Further, in the embodiment, the amplitude correction section 164 is included in the servo amplifier 160, but is not limited thereto, and for example, can be included in the welding power source 140 or the robot control device 120, or a configuration including the amplitude correction section 164 as an independent control device can be included in the welding system 50.

[0162] The servo motor 170 is provided with the motor 61 and the motor encoder 62. Further, the servo amplifier 160 is provided with the amplitude correction section 164, the forward / reverse feed command generation section 161, and the drive control section 70. The amplitude correction section 164 is provided with the actual amplitude detection section 71 and the correction amount calculation section 67. The actual amplitude detection section 71 is provided with the forward / reverse determination section 63, the reverse feed amplitude detection section 641, the forward feed amplitude detection section 642, the filter 651, the filter 652, and the averaging processing section 66. Further, the forward / reverse feed command generation section 161 is provided with the forward / reverse speed command section 68 and the speed command section 69.

[0163] The actual feed speed Vmon is measured from the motor 61 via the motor encoder 62. The forward / reverse determination section 63 determines whether the amplitude is during the forward feed or during the reverse feed, based on the actual feed speed Vmon.

[0164] The reverse feed amplitude detection section 641 detects the amplitude of the reverse feed and outputs the reverse feed actual amplitude amount Ab. The forward feed amplitude detection section 642 detects the amplitude of the forward feed and outputs the forward feed actual amplitude amount Af.

[0165] The reverse feed actual amplitude amount Ab and the forward feed actual amplitude amount Af are subjected to filtering by the filter 651 and the filter 652, and then the averaging processing section 66 performs averaging processing, and the result thereof is output as the actual amplitude amount.

[0166] The deviation E between the target amplitude amount At and the actual amplitude amount is input to the correction amount calculation section 67. The correction amount calculation section 67 is provided with a feedback controller. The feedback controller can be, for example, a PI controller, and in the case of the PI controller, the target amplitude amount At and the actual amplitude amount are input to the feedback controller, and the feedback controller outputs the correction amount. Figure 3The diagram illustrates a PI controller. In the example shown, the correction calculation unit 67 performs PI control for the deviation and outputs an amplitude correction amount Au.

[0167] The forward and reverse speed command unit 68 calculates and outputs the amplitude feed speed Ff based on the amplitude correction amount Au.

[0168] The amplitude feed rate Ff and the average feed rate Favg are input to the speed command unit 69. Based on the amplitude feed rate Ff and the average feed rate Favg, the speed command unit 69 outputs a feed rate command signal Fw.

[0169] Based on the acquired feed speed command signal Fw, the drive control unit 70 outputs an electrical signal for controlling the drive of the motor 61 involved in feed control. Additionally, Figure 2 In the figure, the drive control unit 70 is not shown, but it outputs an electrical signal based on the feed speed command signal Fw to the servo motor 170.

[0170] Figure 4 This is a block diagram illustrating a structural example of a servo amplifier 160 and a servo motor 170, including the amplitude correction unit 164 in this embodiment.

[0171] about Figure 4 The control device shown is related to Figure 3 The control device shown has the same structure, so detailed descriptions are omitted. Figure 4 In this configuration, the correction calculation unit 67 is divided into two parts: a correction calculation unit 671 for forward feed and a correction calculation unit 672 for reverse feed. Accordingly, averaging processing of the actual amplitude of the reverse feed (Ab) and the actual amplitude of the forward feed (Af) is unnecessary. The deviation Ef between the value after applying a filter to the actual amplitude of the forward feed (Af) and the target correction amount At is input to the correction calculation unit 671 for forward feed. The deviation Eb between the value after applying a filter to the actual amplitude of the reverse feed (Ab) and the target correction amount At is input to the correction calculation unit 672 for reverse feed.

[0172] This is similar to the feedback control, such as PI control, performed by the correction calculation unit 671 during forward feed and the correction calculation unit 672 during reverse feed. Figure 3 Same. During forward feed, the correction calculation unit 671 outputs the forward feed amplitude correction amount Auf to the forward and reverse speed command unit 68. During reverse feed, the correction calculation unit 672 outputs the reverse feed amplitude correction amount Aub to the forward and reverse speed command unit 68.

[0173] The forward / reverse speed command section 68 calculates and outputs the 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 referred to here can be a command that adds both the amplitude command value during the forward feed and the amplitude command value during the reverse feed.

[0174] (Variants)

[0175] Variants are described below. In addition, variants include a plurality of modes corresponding to Figure 3 , Figure 4 and so on, and thus the addition of reference numerals is omitted. For example, the correction amount calculation section described below corresponds to Figure 3 the correction amount calculation section 67 in Figure 4 the forward feed period correction amount calculation section 671 and the reverse feed period correction amount calculation section 672 in .

[0176] The correction amount calculation section at least calculates or measures the actual amplitude amount of the welding wire or the error amount of the actual amplitude amount and the target amplitude amount. The actual amplitude amount referred to here is a measured value of the difference (wave height) between the upper end position and the lower end position in one period with the welding wire tip as the base point. The error amount can be calculated as follows. First, the average speed is subtracted from the feed speed. On this basis, the variation amount is calculated from the difference between the current waveform and the pre-prepared sample waveform, and the amount integrated with respect to the variation amount is taken as the error amount. The correction amount calculation section calculates the correction amount of the amplitude based on the actual amplitude amount or the error amount. The speed command section calculates the amplitude command value based on the correction amount of the amplitude.

[0177] In the case of calculating or measuring the actual amplitude amount, in the step of calculating the correction amount, the correction amount calculation section calculates the correction amount (Au) based on the calculated or measured actual amplitude amount (Af, Ab) and the target amplitude amount (At: reference).

[0178] In the forward / reverse speed command section, the value obtained by adding the amplitude correction amount Au and the target amplitude amount At is calculated as the amplitude command value.

[0179] The actual amplitude amount is an amount using at least one of the actual amplitude amount Af during the forward feed, the actual amplitude amount Ab during the reverse feed, or the average actual amplitude amount Afb obtained by averaging the actual amplitude amount during the forward feed and the actual amplitude amount during the reverse feed.

[0180] The actual amplitude amount is detected actual feed speed, and is calculated based on at least any one of the detected actual feed speed, the average feed speed set value, and the average feed speed measured value.

[0181] The actual amplitude amount can be calculated by numerically integrating the actual feeding speed of the welding wire according to a predetermined sampling time, and adding or subtracting a movement amount of the average feeding speed amount to the integrated value for each predetermined welding wire forward and reverse cycle. The sampling time can be, for example, a time determined based on a control period of the control device. For example, the sampling time can be the time of the control period. The predetermined welding wire forward and reverse cycle can be, for example, a half cycle (1 / 2 cycle), but can also be a cycle other than this.

[0182] Figure 5 is a graph showing the relationship of various values regarding the control device in the present embodiment. Figure 5 The horizontal axis of (a) of shows time (radians), and the vertical axis shows the speed of the welding wire tip. Figure 5 The horizontal axis of (b) of shows time (radians), and the vertical axis shows the position of the welding wire tip. In addition, the time (radians) of the horizontal axis indicates the welding wire position phase described above.

[0183] In Figure 5 In (a) of, the feeding speed command signal Fw is represented by Fw = Ff + Favg. At this time, the amplitude feeding speed Ff in the forward feeding period is provided by the following equation. Here, t indicates the time.

[0184] [Num 1]

[0185]

[0186] A uf is the forward feeding amplitude correction amount. In addition, the amplitude feeding speed Ff in the reverse feeding period is provided by the following equation. Here, t indicates the time.

[0187] [Num 2]

[0188]

[0189] A ub is the reverse feeding amplitude correction amount.

[0190] As shown in the figure, the actual feeding speed periodically deviates, that is, a deviation occurs, compared to the set average feeding speed (hereinafter, also referred to as "set average feeding speed"). The control period of the control device is usually shorter than the forward and reverse cycle.

[0191] The actual amplitude amount can also be calculated as a value obtained by numerically integrating a value obtained by subtracting the set average feeding speed from the actual feeding speed of the welding wire according to a predetermined sampling time. That is, the order of the integration operation and the subtraction operation of the set average feeding speed can also be reversed.

[0192] The actual amplitude amount can be calculated as the actual amplitude amount Af in the forward feeding period and the actual amplitude amount Ab in the reverse feeding period.

[0193] There can also be a step of averaging the actual amplitude amount Af during the forward feeding period and the actual amplitude amount Ab during the reverse feeding period to calculate an average actual amplitude amount (refer to Figure 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.

[0194] Further, in the step of calculating the correction amount, as the correction amount, a forward feeding amplitude correction amount Auf based on the actual amplitude amount Af during the forward feeding period and the target amplitude amount At can be at least calculated. Likewise, as the correction amount, a reverse feeding amplitude correction amount Aub based on the actual amplitude amount Ab during the reverse feeding period and the target amplitude amount At can be at least calculated (refer to Figure 4 ).

[0195] (Actual Amplitude Detection Section)

[0196] The actual amplitude detection section includes a unit that detects the actual feeding speed of the welding wire. The actual amplitude detection section includes at least a unit that calculates an actual amplitude amount calculated based on any one of the detected actual feeding speed, the average feeding speed set value, and the average feeding speed measured value. For example, in the structure of Figure 3 , the forward / reverse determination section 63, the reverse feeding amplitude detection section 641, the forward feeding amplitude detection section 642, the filter 651, the filter 652, and the averaging processing section 66 correspond to the actual amplitude detection section described herein.

[0197] (Correction Amount Calculation Section)

[0198] The correction amount calculation section includes a unit that calculates the amplitude correction amount Au based on the actual amplitude amount (the forward feeding actual amplitude amount Af, the reverse feeding actual amplitude amount Ab) and the target amplitude amount At. The correction amount calculation section includes a unit that calculates a value obtained by adding the correction amount and the target amplitude amount as the amplitude command value (At + Au). For example, in the structure of Figure 3 , the correction amount calculation section 67 corresponds to the correction amount calculation section described herein.

[0199] In the above case, the actual amplitude amount calculated in the actual amplitude detection section is at least one of the actual amplitude amount Af during the forward feeding period, the actual amplitude amount Ab during the reverse feeding period, and the average actual amplitude amount Afb obtained by averaging the actual amplitude amounts during the forward feeding period and the reverse feeding period.

[0200] The actual amplitude detection section includes the reverse feeding amplitude detection section, the forward feeding amplitude detection section, and the averaging processing section (refer to Figure 3). The reverse feed amplitude detection section includes a unit that calculates the actual amplitude amount during the reverse feed. The forward feed amplitude detection section includes a unit that calculates the actual amplitude amount during the forward feed. The averaging processing section includes a unit that calculates the average actual amplitude amount from the actual amplitude amount during the reverse feed and the actual amplitude amount during the forward feed.

[0201] As another way, the actual amplitude detection section includes a reverse feed amplitude detection section and a forward feed amplitude detection section (refer to Figure 4 ). In this case, the correction amount calculation section is constituted by both a correction amount calculation section for the forward feed period and a correction amount calculation section for the reverse feed period. The reverse feed amplitude detection section includes a unit that calculates the actual amplitude amount during the reverse feed. The forward feed amplitude detection section includes a unit that calculates the actual amplitude amount during the forward feed. The correction amount calculation section for the forward feed period includes a unit that calculates the forward feed amplitude correction amount Auf during the forward feed based on the actual amplitude amount Af during the forward feed and the target amplitude amount At, and a unit that calculates a value obtained by adding the forward feed amplitude correction amount Auf during the forward feed to the target amplitude amount as the amplitude command value during the forward feed. The correction amount calculation section for the reverse feed period includes a unit that calculates the reverse feed amplitude correction amount Aub during the reverse feed based on the actual amplitude amount Ab during the reverse feed and the target amplitude amount At, and a unit that calculates a value obtained by adding the reverse feed amplitude correction amount Aub during the reverse feed to the target amplitude amount as the amplitude command value during the reverse feed.

[0202] (Regarding the case of calculating or measuring the error amount)

[0203] In the above, the case of calculating or measuring the actual amplitude amount is described. Next, the case of calculating or measuring the error amount is described.

[0204] In the case of calculating or measuring the error amount, in the amplitude correction section 164, at least the amplitude error amount calculation section and the correction amount calculation section are provided. The amplitude error amount calculation section can include a unit that calculates the error amount between the target amplitude amount At and the actual amplitude amount during the forward feed Af, and a unit that calculates the error amount between the target amplitude amount At and the actual amplitude amount during the reverse feed Ab. Figure 3 and Figure 4 in at least a part of the structural elements provided in the above actual amplitude detection section. The correction amount calculation section refers to Figure 3 and Figure 4 corresponding to the above correction amount calculation section.

[0205] The amplitude error amount calculating section has a unit that detects the actual wire feed speed. The amplitude error amount calculating section has at least a unit that calculates the difference between the detected actual wire feed speed and the target feed speed that is the reference, and calculates the amplitude error amount as the value obtained by numerically integrating the difference amount over a predetermined wire feed cycle. The correction amount calculating section has a unit that calculates the value obtained by adding the correction amount and the target amplitude amount as the amplitude command value (At + Au) using the amplitude error amount as the amplitude correction amount Au.

[0206] In the case of calculating the error amount, first, the amplitude error amount calculating section detects the actual wire feed speed. Next, the amplitude error amount calculating section calculates the difference between the detected actual wire feed speed and the target feed speed that is the reference. Then, the amplitude error amount calculating section calculates the error amount as the value obtained by numerically integrating the difference amount over a predetermined wire feed cycle. Then, the correction amount calculating section calculates the amplitude correction amount Au from the amplitude error amount.

[0207] Figure 6 is a graph showing the result of the amplitude correction in the present embodiment. Figure 6 The three graphs showing the progress of the actual feed speed Vmon, the actual amplitude amount Afb, and the amplitude correction amount Au are arranged in the order from the top, and the horizontal axis of each graph shows the time (ms). The target amplitude amount At is 5 mm, and the amplitude correction is started at the 100 ms time point.

[0208] The actual amplitude amount Afb in the initial state before the start of the amplitude correction is about 4.4 mm. When the amplitude correction is started at the 100 ms time point, it can be confirmed that the amplitude correction amount Au increases. Along with this, the wave height of the actual feed speed Vmon gradually increases, and as a result, the actual amplitude amount Afb approaches the target amplitude amount At, and reaches 5 mm, which is the target amplitude amount At, at the 400 ms time point. After that, although there are some fluctuations, a stable state is confirmed near the target amplitude amount At.

[0209] 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 the present embodiment.

[0210] The present application is not limited to the above-described embodiments, and modifications, applications, and the like based on the combination of the structures of the embodiments with each other, the description, and publicly known technologies by those skilled in the art are intended to be included in the scope of the present application.

[0211] As described above, the following matters are disclosed in the present specification.

[0212] (1) A feeding control method in which a welding wire is periodically repeatedly subjected to forward feeding and reverse feeding in accordance with a welding wire forward-reverse frequency in which a forward feeding period and a reverse feeding period are set to one cycle, while feeding the welding wire at a predetermined average welding wire feeding speed,

[0213] The feeding control method is characterized by comprising:

[0214] a step 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;

[0215] a step of calculating a correction amount on the basis of the actual amplitude amount or the error amount; and

[0216] a step of calculating an amplitude command value on the basis of the correction amount.

[0217] (2) The feeding control method according to (1), in which

[0218] in a case where the actual amplitude amount is calculated or measured in the step of calculating or measuring the actual amplitude amount or the error amount,

[0219] in the step of calculating the correction amount, a correction amount is calculated on the basis of the calculated or measured actual amplitude amount and target amplitude amount,

[0220] 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,

[0221] the actual amplitude amount uses at least one of an actual amplitude amount during a forward feeding period, an actual amplitude amount during a reverse feeding period, and an average actual amplitude amount obtained by averaging actual amplitude amounts during the forward feeding period and the reverse feeding period.

[0222] (3) The feeding control method according to (2), in which

[0223] an actual feeding speed of the welding wire is detected,

[0224] the actual amplitude amount is calculated on the basis of at least the detected actual feeding speed and an average feeding speed set value or an average feeding speed measured value.

[0225] (4) The feeding control method according to (3), in which

[0226] a numerical integral of the actual feeding speed of the welding wire is performed in accordance with a predetermined sampling time,

[0227] for the integral result, a moving amount of an average feeding speed amount is added or subtracted per predetermined welding wire forward-reverse cycle, whereby the actual amplitude amount is calculated.

[0228] (5) The feeding control method according to (3), wherein

[0229] The actual amplitude amount is calculated as a value obtained by numerically integrating a value obtained by subtracting the average feeding speed from the actual feeding speed of the welding wire for a predetermined welding wire forward-reverse cycle, according to a predetermined sampling time.

[0230] (6) The feeding control method according to any one of (1) to (5), wherein

[0231] In the step of calculating the actual amplitude amount, the actual amplitude amount is calculated as an actual amplitude amount during the forward feeding period and an actual amplitude amount during the reverse feeding period.

[0232] (7) The feeding control method according to (6), wherein

[0233] the step of calculating an average actual amplitude amount by averaging the calculated actual amplitude amount Af during the forward feeding period and the actual amplitude amount Ab during the reverse feeding period,

[0234] 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.

[0235] (8) The feeding control method according to (6), wherein

[0236] In the step of calculating the correction amount, as the correction amount, at least a correction amount based on the actual amplitude amount during the forward feeding period and a target amplitude amount, and a correction amount based on the actual amplitude amount during the reverse feeding period and a target amplitude amount are calculated.

[0237] (9) The feeding control method according to (1), wherein

[0238] In the case where at least the error amount is calculated in the step of calculating or measuring the actual amplitude amount or the error amount,

[0239] detecting an actual feeding speed of a welding wire,

[0240] calculating at least a difference amount between the detected actual feeding speed and a target feeding speed serving as a reference,

[0241] calculating the error amount as a value obtained by numerically integrating the difference amount for a predetermined welding wire forward-reverse cycle,

[0242] In the step of calculating the correction amount, the error amount is handled as a correction amount.

[0243] (10) A control device that periodically repeats forward feeding and reverse feeding of a welding wire while setting a welding wire forward-reverse frequency that sets a forward feeding period and a reverse feeding period as one cycle, and feeds the welding wire at a predetermined average welding wire feeding speed, characterized by

[0244] The control device includes at least an actual amplitude detection section and a correction amount calculation section,

[0245] The actual amplitude detection section includes:

[0246] a unit that detects an actual feeding speed of the welding wire; and

[0247] a unit that calculates at least an actual amplitude amount that is calculated based on any one of the detected actual feeding speed and an average feeding speed set value and an average feeding speed measured value,

[0248] The correction amount calculation section includes:

[0249] a unit that calculates a correction amount based on the actual amplitude amount and a target amplitude amount; and

[0250] a unit that calculates a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value,

[0251] The actual amplitude amount calculated in the actual amplitude detection section is at least one of an actual amplitude amount during the forward feeding period, an actual amplitude amount during the reverse feeding period, and an average actual amplitude amount obtained by averaging the actual amplitude amounts during the forward feeding period and the reverse feeding period.

[0252] (11) The control device according to (10), wherein

[0253] The actual amplitude detection section includes a reverse feeding amplitude detection section, a forward feeding amplitude detection section, and an averaging processing section,

[0254] The reverse feeding amplitude detection section includes a unit that calculates an actual amplitude amount during the reverse feeding period,

[0255] The forward feeding amplitude detection section includes a unit that calculates an actual amplitude amount during the forward feeding period,

[0256] The averaging processing section includes a unit that calculates an average actual amplitude amount based on the actual amplitude amount during the reverse feeding period and the actual amplitude amount during the forward feeding period.

[0257] (12) The control device according to (10), wherein

[0258] The actual amplitude detection section includes a reverse feeding amplitude detection section and a forward feeding amplitude detection section,

[0259] The correction amount calculation section is composed of a correction amount calculation section for the forward feeding period and a correction amount calculation section for the reverse feeding period,

[0260] The reverse feeding amplitude detection section includes a unit that calculates the actual amplitude amount during the reverse feeding period,

[0261] The forward feeding amplitude detection section includes a unit that calculates the actual amplitude amount during the forward feeding period,

[0262] The correction amount calculation section for the forward feeding period includes:

[0263] a unit that calculates a correction amount during the forward feeding period based on the actual amplitude amount and a target amplitude amount during the forward feeding period; and

[0264] a unit that calculates a value obtained by adding the correction amount during the forward feeding period to the target amplitude amount as an amplitude command value during the forward feeding period,

[0265] The correction amount calculation section for the reverse feeding period includes:

[0266] a unit that calculates a correction amount during the reverse feeding period based on the actual amplitude amount and a target amplitude amount during the reverse feeding period; and

[0267] a unit that calculates a value obtained by adding the correction amount during the reverse feeding period to the target amplitude amount as an amplitude command value during the reverse feeding period.

[0268] (13) A control device that feeds a welding wire periodically in a forward feeding direction and a reverse feeding direction at a predetermined average welding wire feeding speed while setting the forward feeding period and the reverse feeding period as one cycle of a welding wire forward-reverse frequency, the control device characterized by comprising:

[0269] The control device includes at least an amplitude error amount calculation section and a correction amount calculation section,

[0270] The amplitude error amount calculation section includes:

[0271] a unit that detects an actual feeding speed of the welding wire; and

[0272] a unit that calculates at least a difference amount between the detected actual feeding speed and a target feeding speed that serves as a reference, and calculates an amplitude error amount as a value obtained by numerically integrating the difference amount over the predetermined welding wire forward-reverse cycle,

[0273] The correction amount calculation section includes a unit that calculates a value obtained by adding the amplitude error amount to a target amplitude amount as an amplitude command value.

[0274] (14) A servo amplifier including the control device according to any one of (10) to (13).

[0275] (15) A welding system including the servo amplifier according to (14).

[0276] (16) A welding power source including the control device according to any one of (10) to (13).

[0277] (17) A welding system including the welding power source according to (16).

[0278] (18) A wire feeding control program that periodically repeats forward feeding and reverse feeding of a welding wire at a predetermined average wire feeding speed while performing the forward feeding and the reverse feeding of the welding wire based on a wire forward / reverse frequency that sets a forward feeding period and a reverse feeding period as one cycle,

[0279] The wire feeding control program causes a control device to function as:

[0280] a function of calculating or measuring at least an actual amplitude amount of the welding wire or an error amount of the actual amplitude amount from a target amplitude amount;

[0281] a function of calculating a correction amount based on the actual amplitude amount or the error amount; and

[0282] a function of calculating an amplitude command value based on the correction amount.

Claims

1. A feeding control method of feeding a welding wire at a predetermined average welding wire feeding speed while periodically repeating forward feeding and reverse feeding of the welding wire based on a welding wire forward-reverse frequency in which a forward feeding period and a reverse feeding period are set to one cycle. The feeding control method is characterized by comprising: a step 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 step of calculating a correction amount based on the actual amplitude amount or the error amount; and a step of calculating an amplitude command value based on the correction amount.

2. The feeding control method according to claim 1, wherein in a case where 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 actual amplitude amount uses at least one of an actual amplitude amount in the forward feeding period, an actual amplitude amount in the reverse feeding period, and an average actual amplitude amount obtained by averaging the actual amplitude amounts in the forward feeding period and the reverse feeding period.

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

4. The feeding control method according to claim 3, wherein the actual feeding speed of the welding wire is numerically integrated according to a predetermined sampling time, for the integrated result, a moving amount of the average feeding speed amount is added or subtracted for each welding wire forward-reverse cycle, and thus the actual amplitude amount is calculated.

5. The feeding control method according to claim 3, wherein the actual amplitude amount is calculated as a value obtained by numerically integrating a value obtained by subtracting an average feeding speed from the actual feeding speed of the welding wire for a predetermined welding wire forward-reverse cycle.

6. The feeding control method according to any one of claims 1 to 5, wherein 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.

7. The feeding control method according to claim 6, wherein the step of calculating an average actual amplitude amount by averaging the calculated actual amplitude amount in the forward feeding period Af and the actual amplitude amount in the reverse feeding period Ab is further included, 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. The feeding control method according to claim 6, wherein In the step of calculating the correction amount, as the correction amount, at least a correction amount based on the actual amplitude amount during the forward feeding and a correction amount based on the actual amplitude amount during the reverse feeding are calculated.

9. The feeding control method according to claim 1, wherein, in the case where at least the error amount is calculated in the step of calculating or measuring the actual amplitude amount or the error amount, detecting an actual feeding speed of the welding wire, calculating at least a difference amount between the detected actual feeding speed and a target feeding speed serving as a reference, calculating the error amount as a value obtained by numerically integrating the difference amount over a predetermined welding wire forward-reverse cycle, in the step of calculating the correction amount, the error amount is handled as a correction amount.

10. A control device that feeds a welding wire periodically repeating forward feeding and reverse feeding according to a welding wire forward-reverse frequency in which a forward feeding period and a reverse feeding period are set as one cycle, at a predetermined average welding wire feeding speed, the control device is characterized in that, the control device at least includes an actual amplitude detection section and a correction amount calculation section, the actual amplitude detection section includes: a unit that detects an actual feeding speed of the welding wire; and a unit that calculates at least an actual amplitude amount based on either one of the detected actual feeding speed and an average feeding speed set value and an average feeding speed measured value, the correction amount calculation section includes: a unit that calculates a correction amount based on the actual amplitude amount and a target amplitude amount; and a unit that calculates a value obtained by adding the correction amount and the target amplitude amount as an amplitude command value, the actual amplitude amount calculated in the actual amplitude detection section is at least one of an actual amplitude amount during a forward feeding period, an actual amplitude amount during a reverse feeding period, and an average actual amplitude amount obtained by averaging actual amplitude amounts during a forward feeding period and a reverse feeding period.

11. The control device according to claim 10, wherein, the actual amplitude detection section includes a reverse feeding amplitude detection section, a forward feeding amplitude detection section, and an averaging processing section, the reverse feeding amplitude detection section includes a unit that calculates an actual amplitude amount during a reverse feeding period, the forward feeding amplitude detection section includes a unit that calculates an actual amplitude amount during a forward feeding period, the averaging processing section includes a unit that calculates an average actual amplitude amount from an actual amplitude amount during a reverse feeding period and an actual amplitude amount during a forward feeding period.

12. The control device according to claim 10, wherein, the actual amplitude detection section includes a reverse feeding amplitude detection section and a forward feeding amplitude detection section, the correction amount calculation section is constituted by both a correction amount calculation section for a forward feeding period and a correction amount calculation section for a reverse feeding period, the reverse feeding amplitude detection section includes a unit that calculates an actual amplitude amount during a reverse feeding period, the forward feeding amplitude detection section includes a unit that calculates an actual amplitude amount during a forward feeding period, the correction amount calculation section for a forward feeding period includes: a unit that calculates a correction amount in the forward feeding period based on the actual amplitude amount and the target amplitude amount in the forward feeding period; and a unit that calculates a value obtained by adding the correction amount in the forward feeding period to the target amplitude amount as an amplitude command value in the forward feeding period, the correction amount calculation unit for the reverse feeding period includes: a unit that calculates a correction amount in the reverse feeding period based on the actual amplitude amount and the target amplitude amount in the reverse feeding period; and a unit that calculates a value obtained by adding the correction amount in the reverse feeding period to the target amplitude amount as an amplitude command value in the reverse feeding period.

13. A control device that feeds a welding wire periodically repeating forward feeding and reverse feeding according to a welding wire forward-reverse frequency that sets a forward feeding period and a reverse feeding period as one cycle, while feeding the welding wire at a predetermined average welding wire feeding speed, the control device characterized by, the control device at least includes an amplitude error amount calculation unit and a correction amount calculation unit, the amplitude error amount calculation unit includes: a unit that detects an actual feeding speed of the welding wire; and a unit that at least calculates a difference amount between the detected actual feeding speed and a target feeding speed that is a reference, and calculates an amplitude error amount as a value obtained by numerically integrating the difference amount for a predetermined welding wire forward-reverse cycle, the correction amount calculation unit includes a unit that adds the amplitude error amount as a correction amount to a target amplitude amount, and calculates a value after the addition as an amplitude command value.

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

15. A welding system including the servo amplifier according to claim 14.

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

17. A welding system including the welding power source according to claim 16.

18. A recording medium that stores a feeding control program for feeding a welding wire periodically repeating forward feeding and reverse feeding according to a welding wire forward-reverse frequency that sets a forward feeding period and a reverse feeding period as one cycle, while feeding the welding wire at a predetermined average welding wire feeding speed, the feeding control program causes a control device to function as: a function of at least calculating or measuring an actual amplitude amount of the welding wire or an error amount of 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; and a function of calculating an amplitude command value based on the correction amount.

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