Welding system, feed control method, and communication connection method

Abstract

To increase operation accuracy of a tip position of a wire and optimally realize control of a welding condition performed on the basis of at least one of the tip position and feeding speed of the wire in a feeding control method.SOLUTION: A welding system in which the tip of a welding wire is fed toward a base material periodically with a normal feeding period and a reverse feeding period as one period and which controls a welding condition on the basis of at least one of the tip position and feeding speed of the welding wire includes a welding control device, a welding power supply, a servo motor and a servo amplifier. The servo amplifier and the welding power supply are connected directly or indirectly via digital communication. The servo amplifier includes: means of generating a feeding command of normal feeding or reverse feeding on the basis of setting information input via the digital communication; means of outputting a control signal based on the generated feeding command to the servo motor; and means of outputting a synchronization signal pertaining to the generated feeding command to the welding power supply. The welding power supply includes means of calculating a wire position phase on the basis of the synchronization signal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a welding system, a feed control method, and a communication connection method. [Background technology]

[0002] Gas-shielded arc welding has traditionally been used in the manufacturing of automobiles, steel frames, construction machinery, shipbuilding, and various other industries. There is a demand for improvements in welding workability, including the reduction of spatter, in gas-shielded arc welding. One conventional method considered effective in reducing spatter is a welding method (hereinafter also referred to as a "feed control method") in which a forward feed period and a reverse feed period of a welding wire (hereinafter also referred to as a "wire") are periodically repeated, with one cycle consisting of one forward feed period and one reverse feed period, while controlling at least one of the welding conditions based on at least one of the tip position or the feed speed of the welding wire.

[0003] Patent Document 1 discloses that a consumable electrode arc welding power source that supplies welding current to a wire serving as a consumable electrode, which aims to suppress the generation of spatter even when a large current is passed through the wire when arc welding is performed by periodically repeating forward and reverse feed of the tip of the wire serving as a consumable electrode, has a control means that changes the welding current in accordance with the periodically fluctuating tip position of the wire when the tip of the wire is fed toward the base metal while periodically switching between periods of forward feed and periods of reverse feed, thereby making it possible to reduce spatter even in the case of a high current range in which welding can be performed efficiently with high heat input. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-49506 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 achieves spatter reduction by controlling the welding current according to the wire tip position or the wire feed speed. However, the wire tip position is calculated based on the wire feed speed. If the update period of the wire feed speed command (hereinafter referred to as the "forward / reverse feed command") output to the servo amplifier that controls the servo motor for feeding the wire forward or backward is slow, the number of updates by this forward / reverse feed command is limited, resulting in poor accuracy in controlling the wire tip position. Furthermore, a phase mismatch may occur between the forward / reverse feed command and the wire tip position, making it difficult to control the welding current with optimal timing. As a result, the timing of current control may be disrupted, resulting in a failure to achieve spatter reduction and other improvements in welding workability. One factor that slows down the wire feed speed command speed is communication speed. However, in current configurations where feed commands are sent digitally from a control unit within a welding power source to a servo amplifier, the wire feed speed command can only be updated approximately every 1 ms (millisecond). For example, if the frequency when the forward feed period and reverse feed period are one cycle (hereinafter referred to as the "wire forward / reverse frequency") is 100 Hz and the communication speed is 1 ms, only 10 updates are possible. Note that to obtain the effect of improving welding workability, the feed command must be updated at least at a cycle faster than 200 μs. In this case, if the wire forward / reverse frequency is 100 Hz, 50 updates are possible.

[0006] The present invention aims to provide a welding system, a feed control method, and a communication connection method that have high operational accuracy in the wire tip position in a feed control method and can optimally realize control of welding conditions based on at least one of the wire tip position and the feed speed. [Means for solving the problem]

[0007] The present invention comprises the following configurations. (1) A welding system in which a tip end of a welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, and at least one of welding conditions is controlled based on at least one of the tip end position and the feed speed of the welding wire, the welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor; At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication, The servo amplifier means for generating a feed command for forward feed or reverse feed based on the setting information input by the digital communication; a means for outputting a control signal based on the generated feed command to the servo motor; means for outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source has a means for calculating a wire position phase based on the synchronization signal; A welding system comprising: (2) A feed control method in which a tip of a welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, and welding is performed while controlling at least one of the welding conditions based on at least one of the tip position or the feed speed of the welding wire, A welding system including at least a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor, wherein at least the servo amplifier and the welding power source are directly or indirectly connected by digital communication; The servo amplifier generating a feed command for forward feed or reverse feed based on the setting information input by the digital communication; outputting a control signal based on the generated feed command to the servo motor; outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source calculates a wire position phase based on the synchronization signal; Feed control method. (3) A communication connection method for communicating between devices constituting a welding system that controls at least one of welding conditions based on at least one of a tip position and a feed speed of a welding wire so that the tip of the welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, the method comprising: the welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor; At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication, The servo amplifier generating a feed command for forward feed or reverse feed based on setting information input by digital communication from a device other than the servo amplifier among devices constituting the welding system; outputting a control signal based on the generated feed command to the servo motor; outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source calculates a wire position phase based on the synchronization signal; Communication connection method. [Effects of the Invention]

[0008] According to the present invention, the wire feed control method has high operational accuracy for the wire tip position, and it is possible to obtain optimal control of welding conditions based on at least one of the wire tip position and the wire feed speed, thereby achieving good welding workability. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration example of a welding system according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing a schematic configuration relating to control of a welding power source, a welding control device, and a servo amplifier in the present embodiment. [Figure 3]10 is a graph illustrating an example of the relationship between a current setting signal, a speed phase, a position phase, and a synchronization signal. [Figure 4] 1 is a flowchart illustrating task processing in gas-shielded arc welding along a welding sequence. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a gas-shielded arc welding system, a feed control method, and a communication connection method according to the present disclosure will be described in detail with reference to the accompanying drawings.

[0011] Note that this embodiment is an example of a case where a welding robot is used, and the welding control method according to the present disclosure is not limited to the configuration of this embodiment. For example, an automatic welding device using a cart instead of a welding robot body may be applied, or a portable small welding robot may be applied.

[0012] In this embodiment, a gas metal arc welding (hereinafter also referred to as "GMAW") method using a welding wire, which is a consumable electrode, among gas shielded arc welding methods will be described. However, the welding system according to the present disclosure can also be applied to additive manufacturing systems that use gas metal arc welding. Note that the present disclosure also applies to the case of a non-consumable electrode, such as TIG, that uses a filler wire.

[0013] 1 is a schematic diagram showing an example of the configuration of a welding system according to this embodiment. Welding system 50 includes welding robot 110, welding control device 120, welding power source 140, controller 150, servo amplifier 160, servo motor 170, push motor 180, and wire buffer 190. Push motor 180 feeds welding wire 100.

[0014] Welding power source 140 is connected to welding robot 110 via a positive power cable (not shown) 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 (not shown). This connection is for welding with reverse polarity. To perform welding with positive polarity, the polarity of welding power source 140 can be reversed.

[0015] Furthermore, the welding power source 140 and the push motor 180 are connected by a signal line, and the feed speed of the welding wire can be controlled. In the feed control of this embodiment, the push motor 180 rotates only in the forward direction, and the servo motor 170, which will be described later, is switched between the forward and reverse directions.

[0016] 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.

[0017] The welding torch 111 is equipped with a shielding gas nozzle, which serves as a mechanism for ejecting shielding gas. While the shielding gas is not particularly limited, a gas composition that exhibits globular transition is preferable due to the characteristics of the control used in this embodiment. Specifically, it is preferable for the gas to contain at least one gas with a high potential gradient: carbon dioxide, nitrogen, hydrogen, or oxygen. From the viewpoint of versatility, in the case of a mixed gas with argon gas (hereinafter also referred to as "Ar gas"), a system containing at least 10% by volume of carbon dioxide is more preferable, a system containing 90% by volume or more of carbon dioxide is even more preferable, and carbon dioxide alone is even more preferable. The shielding gas is supplied from a shielding gas supply device (not shown).

[0018] 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 inside. Servo motor 170 switches between forward and reverse rotation based on a forward / reverse feed command to control feed. Servo amplifier 160 also enables high-speed calculation processing and includes a forward / reverse feed command generation unit 161, as described below.

[0019] A wire buffer 190 is disposed between the push motor 180 and the servo motor 170. Because the push motor 180 feeds the wire only in the forward direction and the servo motor 170 feeds the wire in both the forward and reverse directions, the feed directions of the push motor 180 and the servo motor 170 may differ. This can create a situation where a large load is likely to be placed on the wire within the feed path. To ensure proper feed control even in such a feeding situation, the wire buffer 190 is provided to prevent buckling of the wire.

[0020] 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.

[0021] In this embodiment, the specific configuration of workpiece 200 is not particularly important, and welding conditions such as joint shape, welding posture, and groove shape are also not particularly important. Welding control device 120 mainly controls the operation of welding robot 110. Therefore, welding control device 120 may also be referred to as a robot controller. Welding control device 120 holds teaching data that predefines 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 data to control the operation of welding robot 110. Furthermore, welding 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.

[0022] As shown in FIG. 1, welding system 50 of the present embodiment is configured such that welding control device 120 is independent from welding power source 140, but welding control device 120 may be provided within welding power source 140.

[0023] Controller 150 is connected to welding control device 120, and creates or displays a program for operating welding robot 110, inputs teaching data, etc. Information input by the user to controller 150 is provided to welding control device 120. Controller 150 may also have a function for manually operating welding robot 110. The connection between controller 150 and welding control device 120 may be wired or wireless.

[0024] In response to a command from welding 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 welding control device 120, welding power source 140 outputs a control signal for push motor 180.

[0025] 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, welding control device 120, and servo amplifier 160 according to this embodiment.

[0026] Welding power source 140 is connected to welding control device 120 via digital communication, and welding control device 120 is connected to servo amplifier 160 via digital communication. That is, servo amplifier 160, welding control device 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 welding control device 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.

[0027] In this embodiment, communication between welding power source 140 and welding control device 120 is via CAN (Controller Area Network), which is one of the industrial field networks, and communication between welding 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.

[0028] (Functional configuration of welding power source) The control system 141 of the welding power source 140 is executed, for example, by the welding control device 120 or a computer (not shown) executing a program. 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 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 time and end time of each of the peak period Dap, the fall period Ddwn, the base period Db, and the rise period Dup related to current control. The wire-tip position conversion unit 36B has a function of obtaining information on the tip position of the welding wire 100.

[0029] The various condition settings for the peak period Dap, fall period Ddwn, base period Db, and rise period Dup related to the current non-suppression period TIP (in this embodiment, the sum of the Dup and Dap periods) and the current suppression 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. In this embodiment, the various condition settings refer to the setting of conditions such as current value, time, or phase.

[0030] The welding current exhibits a pulse waveform that alternates between a current non-suppression period TIP and a current suppression period TIB based on the 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 when the wire tip position is closest to the tip side and 180° is when the wire tip position is closest to the base metal side.

[0031] Based on the setting 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 current non-suppression period TIP and the set current value Ib (hereinafter also referred to as "base current Ib") for the base period Db in the current suppression period TIB, which are calculated by the waveform control table linear calculation unit 37, are set in the current setting unit 36. Note that, as just one example, the sum of the peak current command value Ip from the waveform control table and the manipulated variable Mn may be used as the peak current Iap. In this case, Iap = Ip + Mn. The manipulated variable Mn is calculated based on the voltage setting value Vap and the value Vo of the voltage detection signal.

[0032] In this embodiment, the welding current is basically controlled by two values: peak current Iap and base current Ib. Therefore, the start time of the base period Db represents the time when the base current Ib starts, i.e., the base current start time. Furthermore, the end time of the current suppression period Db represents the time when the base current Ib ends, i.e., the base current end time. The start time of the base period Db, the end time of the base period Db, the duration (time) of the falling period Ddwn, and the duration (time) of the falling period Ddwn are calculated by the waveform control table linear calculation unit 37. The start time of the peak period Dap may be expressed as the peak current start time, and the end time of the peak period Dap may be expressed as the peak current end time.

[0033] 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.

[0034] 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, as described above.

[0035] 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.

[0036] 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.

[0037] 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 provided to the welding tip as an output from the main power supply circuit, and is passed through welding wire 100, which serves as a consumable electrode.

[0038] The welding wire 100 is fed by a push motor 180, 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 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.

[0039] 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.

[0040] 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 (a gap into which the wire can escape when 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.

[0041] 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, in this embodiment, an absolute encoder built into the wire buffer 190 is used, but it is not limited to this. For example, a rotation angle sensor may be used, in which case the serial-to-analog conversion unit 191 may not be provided.

[0042] A voltage setting signal Vap, which is a target value of the voltage to be applied between the welding tip and base metal 200, is provided to current setting unit 36 ​​from voltage setting unit 36C.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] An average feed speed Favg of the welding wire 100 being fed is provided to waveform control table linear calculation unit 37. 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 relating to feed settings may be stored in welding control device 120, and the various pieces of information may be output from welding control device 120 to welding power source 140.

[0049] 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.

[0050] 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.

[0051] The feed setting data unit 35 may store set values ​​such as the wire amplitude Wf, the wire forward / reverse frequency Sf, and the wire forward / reverse cycle Tf in addition to the average feed speed Favg. 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 set values ​​other than these. may be stored as the feeding setting data.

[0052] 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 lower 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.

[0053] The average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle Tf stored in feed setting data unit 35 are input from digital communication unit 42 to digital communication unit 122 of welding control device 120. In this embodiment, the communication of these feed setting data is performed via CAN communication.

[0054] Welding sequence unit 43 processes each task in the following order based on the teaching data: idle, gas flow, arc start, during welding, and anti-stick. Of these tasks, the "during welding" task is controlled primarily by current setting unit 36. In FIG. 2, welding condition information held by welding control device 120 is shown enclosed by a dashed line within welding power source 140 for convenience.

[0055] (Functional configuration of welding control device) As described above, digital communication unit 122 of welding control device 120 receives, via CAN communication, feed setting data such as average feed rate Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle Tf from feed setting data unit 35 of welding power source 140. Welding 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 welding control device 120 and digital communication unit 162 of servo amplifier 160 are connected via EtherCAT (registered trademark) communication.

[0056] (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 to digital communication unit 162 of servo amplifier 160 via EtherCAT (registered trademark) communication. Forward / reverse feed command generation unit 161 of servo amplifier 160 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. Forward / reverse feed command generation unit 161 calculates an amplitude feed speed Ff from the wire amplitude Wf ​​and the wire forward / reverse cycle Tf, and outputs a feed speed command signal Fw to servo motor 170 based on the amplitude feed speed Ff and average feed speed Favg.

[0057] In this embodiment, the feeding speed command signal Fw is expressed by the following equation. Fw=Ff+Favg...Formula (A)

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 3 is a graph illustrating the relationship between the current setting signal CCset, the speed phase, the position phase, and the synchronization signal. The dashed wavy line in the speed phase of the feed speed represents the feed speed indicated by the feed speed command signal Fw. The solid wavy line in the speed phase of the feed speed represents the actual feed speed Fc_com.

[0062] In this embodiment, the phase synchronization signal is at least one of a synchronization signal for the wire position phase and a synchronization signal for the speed phase of the feed speed (hereinafter simply referred to as the "speed phase"). As shown in FIG. 3, the speed phase synchronization signal is ON during the forward feed period (position from 0 to π) and OFF during the reverse feed period (position from π to 2π). On the other hand, the position phase synchronization signal is ON during a period (position from 0.5π to 1.5π) in which the wire tip, when the wire is fed forward or backward, approaches the base metal 200 side from the center position of the wire amplitude wf (position where the wave height is Lm / 2) (position from 0.5π to 1.5π), and OFF during a period (position from 1.5π to 0.5π) in which the wire tip approaches the tip side from the center position of the wire amplitude. In this embodiment, the wave height Lm is the difference (mm) between the position where the wire tip position is closest to the tip side and the position where the wire tip position is closest to the base metal side. When the set value of the wire amplitude wf is set in "mm," the wave height Lm and the wire amplitude wf are the same.

[0063] Based on the phase synchronization signal and the aforementioned phase delay correction amount, wire tip position conversion unit 36B in welding power source 140 determines the wire position phase of welding wire 100. Current setting unit 36 ​​sets various current values ​​that define the welding current flowing through welding wire 100 based on the determined wire position phase. That is, welding conditions are controlled by determining the wire position phase based on the aforementioned database and synchronization signal. Note that in this embodiment, this control of welding conditions is timing correction of waveform control of the welding current. Here, in this embodiment, the phase delay correction amount corresponds to Deg-adj shown in FIG. 3, and the wire position phase is determined based on the phase synchronization signal whose phase has been corrected by Deg-adj.

[0064] Note that welding conditions may be controlled without providing a database in the phase delay correction unit 38. To achieve this, the phase delay correction amount is calculated by reading the operating cycle of the servo motor 170 using an encoder (not shown) or the like. That is, the servo amplifier 160 has an encoder that receives setting information and an operating signal of the servo motor 170, such as a phase signal for forward and reverse feed operation, and calculates the difference, such as the phase shift, between the feed command generated by the servo amplifier 160 and the operating signal of the servo motor 170. The welding conditions may be controlled in the welding power source 140 by determining the wire position phase based on the difference and a synchronization signal. Note that the control of the welding conditions may be performed by correcting the timing of waveform control of the welding current.

[0065] FIG. 4 is a flowchart illustrating task processing in gas-shielded arc welding along a welding sequence.

[0066] First, feed setting data is stored in advance in feed setting data unit 35 of welding power source 140. The feed setting data includes an average feed speed Favg, a wire amplitude Wf, a wire forward / reverse frequency Sf, and a wire forward / reverse cycle Tf.

[0067] Welding power source 140 transmits the feed setting data to welding control device 120 (S1). This transmission may be performed via CAN communication or EtherCAT (registered trademark) communication.

[0068] Welding control device 120 transmits the feed setting data to servo amplifier 160 (S2). This transmission may be performed by EtherCAT (registered trademark) communication.

[0069] The forward / reverse feed command generating unit 161 of the servo amplifier 160 calculates a feed speed command signal Fw that serves as the basis for driving and controlling the servo motor 170 based on the acquired feed setting data, i.e., the average feed speed Favg, the wire amplitude Wf, the wire forward / reverse frequency Sf, and the wire forward / reverse period Tf (S3).

[0070] In this embodiment, welding power source 140 is connected to welding control device 120 via digital communication, and welding control device 120 is connected to servo amplifier 160 via digital communication, so the above steps S1 and S2 are processed. However, this is not limiting, and processing may be performed according to the network connection configuration of each device. For example, a network connection configuration in which servo amplifier 160 and welding power source 140 are connected via digital communication, and welding power source 140 and welding control device 120 are connected via digital communication, is also possible. In this case, the feed setting data for average feed speed Favg, wire amplitude Wf, wire forward / reverse frequency Sf, and wire forward / reverse cycle Tf may be stored in either welding power source 140 or welding control device 120. If the feed setting data is stored in welding power source 140, the feed setting data is transmitted from welding power source 140 to servo amplifier 160 via EtherCAT (registered trademark) communication. If the feed setting data is stored in the welding control device 120, for example, the feed setting data can be transmitted from the welding control device 120 to the welding power source 140 via CAN communication, and then transmitted from the welding power source 140 to the servo amplifier 160 via EtherCAT (registered trademark) communication.

[0071] In step S4, processing begins in welding sequence unit 43. The tasks "idle," "gas flow," and "arc start" are tasks that are generally performed in gas-shielded arc welding, and therefore detailed explanations thereof will be omitted.

[0072] In step S5, after a predetermined time has elapsed since the task of welding sequence unit 43 became "welding", servo motor 170 is controlled based on feed speed command signal Fw. Furthermore, synchronization signal generating unit 163 generates at least one phase synchronization signal out of the above-mentioned speed phase synchronization signal or position phase synchronization signal based on feed speed command signal Fw, and outputs the generated synchronization signal to welding power source 140.

[0073] In step S6, the welding power source 140 corrects the phase shift of the phase synchronization signal based on the phase delay correction amount calculated by the phase delay correction unit 38 of the welding power source 140. The welding power source 140 inputs the corrected phase synchronization signal to the wire tip position conversion unit 36B, and calculates the real-time wire position phase of the welding wire 100. Note that although correcting the phase shift is more preferable from the viewpoint of the operating accuracy of the wire tip position, the welding power source 140 may input the phase synchronization signal directly to the wire tip position conversion unit 36B without correcting it.

[0074] Based on the real-time wire position phase of welding wire 100 calculated in step S6, welding current control by welding power source 140 is performed (step S7). In this embodiment, the control of welding conditions is performed by controlling the waveform of the welding current. However, the control of welding conditions in step S7 is not limited to controlling the waveform of the welding current, and may include, for example, control of the waveform of the arc voltage or the welding speed among the welding conditions. For example, multiple welding conditions may be controlled, such as controlling the waveform of the welding current and the waveform of the arc voltage.

[0075] In S8, the processes of steps S5 to S7 are continued while the task of welding sequence unit 43 is "welding", and when the "welding" task is completed, "anti-stick" control is performed and welding is completed. Note that the "anti-stick" task is a task that is generally performed in gas-shielded arc welding, so a detailed explanation of it will be omitted.

[0076] The above steps S1 to S8 enable smooth data transmission by digital communication. In addition, by generating a forward / reverse feed command signal (feed speed command signal Fw) using the servo amplifier 160, which is capable of high-speed calculation processing, the movement of the tip of the wire can be grasped with high accuracy.

[0077] A synchronization signal is output from servo amplifier 160 to welding power source 140, and welding conditions such as the welding current are controlled based on the synchronization signal, thereby enabling more advanced control.

[0078] Therefore, in the welding system 50 of the present disclosure, the wire tip position is highly accurately controlled in the feed control method, and control such as welding current waveform control based on at least one of the wire tip position or the feed speed can be optimally realized.

[0079] 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.

[0080] As described above, the present specification discloses the following:

[0081] (1) A welding system in which a tip end of a welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, and at least one of welding conditions is controlled based on at least one of the tip end position and the feed speed of the welding wire, the welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor; At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication, The servo amplifier means for generating a feed command for forward feed or reverse feed based on the setting information input by the digital communication; a means for outputting a control signal based on the generated feed command to the servo motor; means for outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source has a means for calculating a wire position phase based on the synchronization signal; A welding system comprising: According to this welding system, the feed control method has high operational accuracy for the wire tip position, and can optimally realize control of welding conditions based on at least one of the wire tip position and the feed speed.

[0082] (2) The welding system according to (1), wherein the synchronization signal is based on at least one of a wire position phase and a speed phase of a feed speed. According to this welding system, synchronization can be achieved between the servo motor and the welding power source based on the wire position phase or the speed phase of the feed speed.

[0083] (3) The servo amplifier is a means for receiving the setting information and an operation signal of the servo motor and calculating a difference between the generated feed command and the operation signal of the servo motor, The welding power source includes: a means for controlling the welding conditions based on the difference and the synchronization signal; Having The welding system according to (1) or (2), characterized by: According to this welding system, the servo amplifier is capable of high-speed calculation processing, so it can accurately detect the discrepancy between the feed command based on the setting information and the actual operation of the servo motor, and correct the discrepancy with high precision.

[0084] (4) The welding power source is a database including data in which a difference between the setting information and the operation signal of the servo motor is calculated in advance; a means for controlling the welding conditions based on the database and the synchronization signal; Having The welding system according to any one of (1) to (3), characterized by: According to this welding system, welding conditions such as the timing of waveform control of the welding current controlled by the welding power source can be appropriately synchronized with the servo motor that controls the wire feed.

[0085] (5) The welding system according to any one of (1) to (4), wherein the setting information includes at least one setting value of an average feed speed, a wire amplitude, a wire forward / reverse frequency, and a wire forward / reverse cycle. According to this welding system, the servo motor can generate a feed command for forward feed or reverse feed based on the set value.

[0086] (6) The welding power source and the servo amplifier are connected by at least analog input / output, At least the synchronization signal is input to the welding power source from the servo amplifier via the analog input / output; The welding system according to any one of (1) to (5), characterized by: According to this welding system, the setting information is transmitted by digital communication, while the synchronization signal is transmitted by analog communication, thereby enabling efficient use of digital communication and analog communication depending on the application.

[0087] (7) The welding system includes a wire buffer device and a push motor, the wire buffer device has a sensor for detecting a buffer amount of the wire, The welding power source has a means for controlling the push motor based on the input buffer amount. The welding system according to any one of (1) to (6), characterized by: According to this welding system, it is possible to prevent a large load from being applied to the wire in the feed path between the push motor and the servo motor.

[0088] (8) A feed control method in which a tip of a welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, and welding is performed while controlling at least one of the welding conditions based on at least one of the tip position or the feed speed of the welding wire, A welding system including at least a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor, wherein at least the servo amplifier and the welding power source are directly or indirectly connected by digital communication; The servo amplifier generating a feed command for forward feed or reverse feed based on the setting information input by the digital communication; outputting a control signal based on the generated feed command to the servo motor; outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source calculates a wire position phase based on the synchronization signal; Feed control method. According to this feed control method, the operation accuracy of the wire tip position is high, and it is possible to optimally realize control of the welding conditions based on at least one of the wire tip position and the feed speed.

[0089] (9) A communication connection method for communicating between devices constituting a welding system that controls at least one of welding conditions based on at least one of a tip position and a feed speed of a welding wire so that the tip of the welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, the method comprising: the welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor; At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication, The servo amplifier generating a feed command for forward feed or reverse feed based on setting information input by digital communication from a device other than the servo amplifier among devices constituting the welding system; outputting a control signal based on the generated feed command to the servo motor; outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source calculates a wire position phase based on the synchronization signal; Communication connection method. According to this communication connection method, the wire tip position can be controlled with high accuracy in the feed control method, and the welding conditions can be optimally controlled based on at least one of the wire tip position and the feed speed.

[0090] (10) The digital communication is digital communication connected via an industrial field network, The communication connection method described in (9) is characterized in that the servo amplifier, the welding control device, and the welding power source are connected in this order, or the servo amplifier, the welding power source, and the welding control device are connected in a line type order. According to this communication connection method, setting information can be smoothly transmitted between devices that make up a welding system by utilizing an industrial field network. [Explanation of symbols]

[0091] 1 Three-phase 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 100 welding wire 110 Welding Robot 111 Welding Torch 120 Welding control device 122 Digital Communications Department 123 Digital Communications Department 140 Welding power source 141 Control System Department 150 Controller 160 Servo amplifier 161 Forward / reverse feed command generation unit 162 Digital Communications Department 163 Synchronization signal generator 170 Servo motor 180 Push Motor 190 Wire Buffer 191 Serial to Analog Converter 200 Work

Claims

1. A welding system in which a tip end of a welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, and at least one of welding conditions is controlled based on at least one of a tip end position and a feed speed of the welding wire, the welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor; At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication, The servo amplifier means for generating a feed command for forward feed or reverse feed based on the setting information input by the digital communication; a means for outputting a control signal based on the generated feed command to the servo motor; means for outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source has a means for calculating a wire position phase based on the synchronization signal; A welding system comprising:

2. The welding system of claim 1 , wherein the synchronization signal is based on at least one of a wire position phase and a speed phase of a feed speed.

3. The servo amplifier a means for receiving the setting information and an operation signal of the servo motor and calculating a difference between the generated feed command and the operation signal of the servo motor, The welding power source includes: A means for controlling the welding conditions based on the difference and the synchronization signal. Having The welding system of claim 2 .

4. The welding power source includes: a database including data in which a difference between the setting information and the operation signal of the servo motor is calculated in advance; a means for controlling the welding conditions based on the database and the synchronization signal; Having The welding system of claim 2 .

5. The setting information is 5. The welding system according to claim 1, further comprising at least one set value selected from the group consisting of an average feed rate, a wire amplitude, a wire forward / reverse frequency, and a wire forward / reverse cycle.

6. The welding power source and the servo amplifier are connected by at least analog input / output, At least the synchronization signal is input to the welding power source from the servo amplifier via the analog input / output; 5. The welding system according to claim 1, wherein:

7. the welding system includes a wire buffer device and a push motor; the wire buffer device has a sensor for detecting a buffer amount of the wire, The welding power source has a means for controlling the push motor based on the input buffer amount.

5. The welding system according to claim 1, wherein:

8. A feed control method for welding, wherein a tip end of a welding wire is fed toward a base metal while periodically repeating a forward feed period and a reverse feed period as one cycle, and welding is performed while controlling at least one of a tip position of the welding wire and a feed speed, the method comprising: A welding system including at least a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor, wherein at least the servo amplifier and the welding power source are directly or indirectly connected by digital communication; The servo amplifier generating a feed command for forward feed or reverse feed based on the setting information input by the digital communication; outputting a control signal based on the generated feed command to the servo motor; outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source calculates a wire position phase based on the synchronization signal; Feed control method.

9. A communication connection method for communicating between devices constituting a welding system that controls at least one of welding conditions based on at least one of a tip position and a feed speed of a welding wire so that a tip of the welding wire is fed toward a base metal while cyclically repeating a forward feed period and a reverse feed period as one cycle, comprising: the welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor; At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication, The servo amplifier generating a feed command for forward feed or reverse feed based on setting information input by digital communication from a device other than the servo amplifier among devices constituting the welding system; outputting a control signal based on the generated feed command to the servo motor; outputting a synchronization signal related to the generated feed command to the welding power source; the welding power source calculates a wire position phase based on the synchronization signal; Communication connection method.

10. the digital communication is digital communication connected via an industrial field network, 10. The communication connection method according to claim 9, wherein the servo amplifier, the welding control device, and the welding power source are connected in this order, or the servo amplifier, the welding power source, and the welding control device are connected in a line type order.

Images