JP5855848B2 - Arc welding system - Google Patents

Description

The present invention relates to an arc welding system.

  Conventionally, a welding method that repeats a droplet transfer period and a cooling period is known (see, for example, Patent Document 1). In this welding method, the droplet is transferred from the consumable electrode to the base material during the droplet transfer period. During the droplet transfer period, the welding torch holding the consumable electrode is stopped with respect to the base material. Thus, a circular molten pool is formed in plan view during the droplet transfer period. On the other hand, during the cooling period, a slight welding current that does not transfer droplets from the consumable electrode to the base material is allowed to flow from the consumable electrode to the base material. Further, during the cooling period, the welding torch is moved to a point in the base material where the next droplet transfer period starts. During the cooling period, the molten pool is solidified to form welding marks. The droplet transfer period and the cooling period as described above are repeated. As a result, a scaly bead is formed in which circular welding marks are continuous in one direction.

  In the conventional welding method, the welding robot or the welding power supply device controls the length of each droplet transfer period to be a certain length. In such a method, the length of each droplet transfer period is unlikely to be a fixed length and often varies. When the length of each droplet transfer period varies, the size of the circular weld mark varies. If it does so, the width | variety of a bead will become non-uniform | heterogenous and will cause the deterioration of the external appearance of a bead. As an application related to the present application, there is Japanese Patent Application No. 2011-3014 (not disclosed at the time of application).

Japanese Patent Laid-Open No. 11-267839

  The present invention has been conceived under the circumstances described above, and an object thereof is to provide an arc welding system and an arc welding method capable of forming a bead having a uniform width.

  According to the first aspect of the present invention, a plurality of droplet transfer periods for transferring the droplets from the consumable electrode and a cooling period for cooling the molten pool formed in the base material after the droplet transfer period are provided. An arc welding method that is repeated a plurality of times, and during each droplet transfer period, a current of a unit pulse waveform including a peak period in which current flows at a peak value and a base period in which current flows at a base value smaller than the peak value. A step of repeatedly flowing the consumable electrode, a step of moving the consumable electrode in the welding progress direction during each cooling period, and a standard pulse that is the number of times of the peak period per set time based on a set time A number calculating step, and when the number of times of the peak period in the droplet transfer period reaches a set number, a pulse number control step for ending the droplet transfer period, and the length of the droplet transfer period being set A time control step of ending the droplet transfer period, the time control step is performed when the switching control circuit receives a preliminary welding start instruction signal from the operation unit, An arc welding method is provided in which the pulse number control step is performed when the switching control circuit receives a main welding start instruction signal from the operation unit.

  According to the second aspect of the present invention, a droplet transfer period in which a pulse current is supplied to the consumable electrode and a cooling period in which the molten pool formed in the base material is cooled after the droplet transfer period are each repeated a plurality of times. An arc welding system comprising an output circuit, wherein the waveform of the pulse current has a shape of repeating a unit pulse waveform including a peak period in which current flows at a peak value and a base period in which current flows at a base value smaller than the peak value. A set time storage unit that stores a set time, a set number storage unit that stores a set number, and a standard pulse number that is the number of times of the peak period per the set time is calculated based on the set time. A pulse number calculation circuit; an end determination circuit for sending an end instruction signal when the number of times of the peak period in the droplet transfer period reaches the set number; a first mode instruction signal; A switching control circuit that sends a mode instruction signal, and the end determination circuit sends a set time arrival signal when the length of the droplet transfer period reaches the set time, and the droplet When the number of peak periods in the transition period reaches the set number, a pulse number comparison circuit that sends a set number arrival signal and an end instruction switching circuit, the end instruction switching circuit includes the first mode instruction signal The first mode is received, and the second mode is received when the second mode instruction signal is received. In the first mode, the end instruction switching circuit receives the set time arrival signal in the first mode. In the second mode, the end instruction signal is sent when the set number arrival signal is received, and the output circuit ends the droplet transfer period when the end instruction signal is received. You , Arc welding system is provided.

  According to such a configuration, the end of the droplet transfer period can be determined based on the number of peak periods in the droplet transfer period. Therefore, the size of the circular welding mark formed in each droplet transfer period can be made uniform. Therefore, it is possible to form a clean bead having a uniform width.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a figure which shows the structure of the arc welding system concerning the 1st reference example of this invention. It is a figure which shows the internal structure of the arc welding system shown in FIG. FIG. 3 is a block diagram illustrating an example of a current waveform generation circuit in FIG. 2. It is a timing chart of the signal etc. in the welding method concerning the 1st reference example of the present invention. It is a figure which shows the timing chart shown in FIG. 4 in detail. (A) is a figure which shows the state of the arc etc. during the droplet transfer period of the welding method concerning the 1st reference example of this invention. (B) is a figure which shows the state of the arc etc. at the time of the start of the cooling period of the welding method concerning the 1st reference example of this invention. (C) is a figure which shows the state of the arc etc. at the time of completion | finish of the cooling period of the welding method concerning the 1st reference example of this invention. (D) is a figure which shows states, such as an arc at the time of the restart of the droplet transfer period of the welding method concerning the 1st reference example of this invention. It is a top view which shows the shape of the bead formed by the welding method concerning the 1st reference example of this invention. It is a figure which shows the internal structure of the arc welding system concerning the 2nd reference example of this invention. It is a figure which shows the internal structure of the arc welding system concerning the 3rd reference example of this invention. It is a timing chart of the signal etc. in the welding method concerning the 3rd reference example of the present invention. It is a figure which shows the timing chart shown in FIG. 10 in detail. It is a figure which shows the internal structure of the arc welding system concerning the 4th reference example of this invention. It is a figure which shows the internal structure of the arc welding system concerning the 5th reference example of this invention. FIG. 14 is a block diagram of an end determination circuit shown in FIG. 13. It is a timing chart of the signal etc. in the welding method concerning the 5th reference example of the present invention. It is a figure which shows the internal structure of the arc welding system concerning 1st Embodiment of this invention. It is a timing chart of the signal etc. in the welding method concerning a 1st embodiment of the present invention. It is a figure which shows the internal structure of the arc welding system concerning 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an arc welding system according to a first reference example of the present invention.

  An arc welding system A11 shown in FIG. 1 includes a welding robot 1, a robot control device 2, and a welding power source device 3. The welding robot 1 automatically performs arc welding on the base material W. Base material W is, for example, an aluminum alloy having a thickness of 1 mm. The welding robot 1 includes a base member 11, a plurality of arms 12, a plurality of motors 13, a welding torch 14, a wire feeding device 16, and a coil liner 19.

  The base member 11 is fixed to an appropriate location such as a floor. Each arm 12 is connected to the base member 11 via a shaft. The welding torch 14 guides the consumable electrode 15 (welding wire) to a predetermined position near the base material W. The welding torch 14 is provided with a shield gas nozzle (not shown). The shield gas nozzle is for supplying a shield gas such as argon. The motor 13 is a moving mechanism and is rotationally driven by the robot control device 2. By this rotational drive, the movement of each arm 12 is controlled, and the welding torch 14 can move freely up and down, front and rear, and left and right.

  The motor 13 is provided with an encoder (not shown). The output of the encoder is sent to the robot control device 2. The wire feeding device 16 is provided in the upper part of the welding robot 1. The wire feeding device 16 is for feeding the consumable electrode 15 to the welding torch 14. The wire feeding device 16 includes a feeding mechanism 161 (motor WM), a wire reel (not shown), and a wire push device (not shown). Using the feeding mechanism 161 as a drive source, the wire push device feeds the consumable electrode 15 wound around the wire reel to the welding torch 14.

  One end of the coil liner 19 is connected to the wire feeder 16 and the other end is connected to the welding torch 14. The coil liner 19 has a tube shape, and a consumable electrode 15 is inserted through the coil liner 19. The coil liner 19 guides the consumable electrode 15 delivered from the wire feeder 16 to the welding torch 14. The fed consumable electrode 15 protrudes from the welding torch 14.

  FIG. 2 is a diagram showing an internal configuration of the arc welding system A11 shown in FIG.

  The robot control device 2 includes an operation control circuit 21 and a teach pendant 23. The robot control device 2 is for controlling the operation of the welding robot 1.

  The operation control circuit 21 has a microcomputer and a memory (not shown). The memory stores a work program in which various operations of the welding robot 1 are set. The operation control circuit 21 sets the robot moving speed VR. The robot moving speed VR is the speed of the welding torch 14 with respect to the base material W in the in-plane direction of the base material W. The operation control circuit 21 sends an operation control signal Ms to the welding robot 1 based on the work program, the coordinate information from the encoder, the robot moving speed VR, and the like. The welding robot 1 receives the operation control signal Ms and rotates each motor 13. By rotating the motors 13, the welding torch 14 moves to a predetermined welding start position on the base material W or moves along the in-plane direction of the base material W. The operation control circuit 21 sends a droplet transfer start signal Ss.

  The teach pendant 23 is connected to the operation control circuit 21. The teach pendant 23 is for the user of the arc welding system A11 to set parameters and the like when performing welding.

  The welding power supply device 3 includes an output circuit 31, a current value storage unit 33, an end determination circuit 34, a set number storage unit 35, and a feed control circuit 38. The welding power source device 3 is a device for supplying the welding current Iw while applying the welding voltage Vw between the consumable electrode 15 and the base material W, and is a device for feeding the consumable electrode 15. .

  The current value storage unit 33 stores the second value ir2. The set number storage unit 35 stores the set number Nb. Each value of the second value ir2 and the set number Nb is input from the teach pendant 23 and stored in each storage unit via the operation control circuit 21, for example.

  The output circuit 31 includes a power supply circuit 311, a current detection circuit 312, a current error calculation circuit EI, a current switching circuit 313, a current control circuit 314, a current waveform generation circuit 315, a signal generation circuit 316, and a voltage detection. A circuit 317, a voltage error calculation circuit EV, and a voltage control circuit 318 are included. The output circuit 31 applies the welding voltage Vw at a value designated between the consumable electrode 15 and the base material W, or allows the welding current Iw to flow at a value designated from the consumable electrode 15 to the base material W. Is.

  The power supply circuit 311 receives, for example, a commercial power supply such as three-phase 200 V, performs output control such as inverter control and thyristor phase control, and outputs a welding voltage Vw and a welding current Iw.

  The current detection circuit 312 is for detecting the value of the welding current Iw flowing between the consumable electrode 15 and the base material W. The current detection circuit 312 sends a current detection signal Id corresponding to the value of the welding current Iw. The current error calculation circuit EI is for calculating a difference ΔIw between the value of the welding current Iw that is actually flowing and the set value of the welding current. The current error calculation circuit EI receives a current detection signal Id and a current setting signal Ir described later corresponding to the set welding current value, and sends a current error signal Ei corresponding to the difference ΔIw to the power supply circuit 311. The current error calculation circuit EI may send a current error signal Ei corresponding to a value obtained by amplifying the difference ΔIw.

  The voltage detection circuit 317 is for detecting the value of the welding voltage Vw applied between the consumable electrode 15 and the base material W. The voltage detection circuit 317 sends a voltage detection signal Vd corresponding to the value of the welding voltage Vw. In this reference example, the voltage detection circuit 317 sends a voltage detection signal Vd corresponding to the time average value of the welding voltage Vw. The voltage control circuit 318 is for setting the value of the welding voltage Vw applied between the consumable electrode 15 and the base material W. The voltage control circuit 318 sends a voltage setting signal Vr for instructing the value of the welding voltage Vw based on a setting voltage value stored in a storage unit (not shown). The voltage error calculation circuit EV is for calculating a difference ΔVw between the value of the welding voltage Vw actually applied and the value of the set welding voltage. The voltage error calculation circuit EV receives the voltage detection signal Vd and the voltage setting signal Vr corresponding to the set welding voltage value, and sends a voltage error signal Ev corresponding to the difference ΔVw. The voltage error calculation circuit EV may send a voltage error signal Ev corresponding to a value obtained by amplifying the difference ΔVw.

  The signal generation circuit 316 is for repeatedly generating the pulse generation instruction signal Ps. In this reference example, the signal generation circuit 316 is a voltage frequency conversion circuit. Therefore, the signal generation circuit 316 receives the voltage error signal Ev, converts the difference ΔVw into a frequency (1 / Tf) proportional to the difference ΔVw, and changes to a high level for a short period every period Tf. Send Ps. Since the frequency (1 / Tf) is proportional to the difference ΔVw, the period Tf is not a constant value but varies somewhat.

  The current waveform generation circuit 315 is for generating a waveform of the welding current Iw in a droplet transfer period T1 described later. Specifically, the current waveform generation circuit 315 generates a unit pulse waveform (the waveform of the welding current Iw in the period Tf in FIG. 5C) every time the pulse generation instruction signal Ps is received. The current waveform generation circuit 315 sends a current setting signal Ir1 corresponding to the generated waveform current.

  FIG. 3 is a block diagram illustrating an example of the current waveform generation circuit 315. The block diagram of the current waveform generation circuit 315 shown in the figure is for generating the unit pulse waveform shown in FIG. 5C, and if the unit pulse waveform is different from that shown in FIG. 5C. The block diagram of the current waveform generation circuit 315 is also different from that in FIG.

  As shown in the figure, the current waveform generation circuit 315 includes a timer circuit TM, a switching circuit SW, current control circuits IPR and IBR, an increase period storage unit TU, a peak period storage unit TP, and a decrease period storage unit. It has TD, peak current memory | storage part IP, and base current memory | storage part IB.

  The increase period storage unit TU stores the increase period Tu, the peak period storage unit TP stores the peak period Tp, the decrease period storage unit TD stores the decrease period Td, and the peak current storage unit IP stores the peak current value ip. The base current storage unit IB stores the base current value ib.

  The timer circuit TM receives the pulse generation instruction signal Ps and sends a period signal tss. The period signal tss is at a high level for a preset period Ts (see FIG. 5C) from the time when the pulse generation instruction signal Ps changes to a high level. The current control circuit IPR receives the period signal tss and sends a current setting signal ipr. The current control circuit IPR is connected to the increase period storage unit TU, the peak period storage unit TP, the decrease period storage unit TD, and the peak current storage unit IP. The current control circuit IPR generates a current setting signal ipr for causing the welding current Iw to have a waveform in the period Ts shown in FIG. 5 from the time when the period signal tss becomes High level (ta (1) in FIG. 5). Generate. The current control circuit IBR is connected to the base current storage unit IB. The current control circuit IBR generates a current setting signal ibr for making the welding current Iw the base current value ib.

  The switching circuit SW receives the period signal tss and the current setting signals ipr and ibr and sends the current setting signal Ir1. While the period signal tss is at the High level, the switching circuit SW sends the current setting signal ipr to the current switching circuit 313 as the current setting signal Ir1. On the other hand, while the period signal tss is at the low level, the switching circuit SW sends the current setting signal ibr to the current switching circuit 313 as the current setting signal Ir1. As described above, the current waveform generation circuit 315 generates the unit pulse waveform shown in FIG. 5C and sends the current setting signal Ir1.

  The current control circuit 314 shown in FIG. 2 is for setting the value of the welding current Iw flowing between the consumable electrode 15 and the base material W in the cooling period T2 described later. The current control circuit 314 sends a current setting signal Ir2 for causing the welding current Iw to flow at the second value ir2.

  The current switching circuit 313 switches the power supply characteristic (constant voltage characteristic or constant current characteristic) of the output circuit 31. When the power supply characteristic of the output circuit 31 is a constant voltage characteristic, the output of the output circuit 31 is controlled so that the value of the welding voltage Vw becomes a set value. On the other hand, when the power supply characteristic of the output circuit 31 is a constant current characteristic, the output of the output circuit 31 is controlled so that the value of the welding current Iw becomes a set value. More specifically, it is as follows. The current switching circuit 313 receives current setting signals Ir1 and Ir2, a droplet transfer start signal Ss described later, and an end instruction signal Es described later. When the current switching circuit 313 receives the droplet transfer start signal Ss, the switch in the current switching circuit 313 is connected to the a side in FIG. In this case, the power supply characteristic of the output circuit 31 is a constant voltage characteristic. That is, the current switching circuit 313 sends the current setting signal Ir1 as the current setting signal Ir to the current error calculation circuit EI, and the welding voltage Vw becomes a value set by the voltage control circuit 318. On the other hand, when the current switching circuit 313 receives the end instruction signal Es, the switch in the current switching circuit 313 is connected to the b side in FIG. In this case, the power supply characteristic of the output circuit 31 is a constant current characteristic. That is, the current switching circuit 313 sends the current setting signal Ir2 as the current setting signal Ir to the current error calculation circuit EI, and the welding current Iw becomes a value set by the current control circuit 314.

  The end determination circuit 34 is for determining whether or not to end the droplet transfer period T1. The end determination circuit 34 includes a measurement circuit 341 and a comparison circuit 342. The measuring circuit 341 is for measuring the number Ns of peak periods Tp in each droplet transition period T1 (that is, the number of unit pulse waveforms of the welding current Iw in each droplet transition period T1). In the present reference example, the measurement circuit 341 measures the number Ns of peak periods Tp based on the number of times the pulse generation instruction signal Ps is generated. When the number Ns of peak periods Tp in each droplet transfer period T1 reaches the set number Nb stored in the set number storage unit 35, the comparison circuit 342 outputs an end instruction signal Es to the output circuit 31 (current in this reference example). To the switching circuit 313) and the operation control circuit 21.

  The feed control circuit 38 is for controlling the speed at which the consumable electrode 15 is fed from the welding torch 14 (feed speed Fw). The feed control circuit 38 sends a feed speed control signal Fc for instructing the feed speed Fw to the feed mechanism 161.

  Next, an arc welding method using the arc welding system A11 will be described with further reference to FIGS. FIG. 4 is a timing chart of signals and the like in the arc welding method using the arc welding system A11. FIG. 4A shows a change state of the robot moving speed VR, FIG. 5B shows a connection state of the switch Sw in the current switching circuit 313 (change state of power supply characteristics), and FIG. 5C shows a change state of the welding current Iw. (D) shows the changing state of the welding voltage Vw, (e) shows the changing state of the feeding speed Fw, (f) shows the changing state of the droplet transfer start signal Ss, (g) The change state of the end instruction signal Es is shown, and (h) shows the change state of the pulse generation instruction signal Ps. In FIG. 6B, a high level indicates that the switch Sw of the current switching circuit 313 is connected to the a side, and a low level indicates that the switch Sw is connected to the b side.

  In the arc welding method using the arc welding system A11, the droplet transfer period T1 and the cooling period T2 are alternately repeated. That is, each of the droplet transfer period T1 and the cooling period T2 is repeated a plurality of times. The droplet transfer period T1 is, for example, 0.1 to 0.5 seconds. The cooling period T2 is, for example, 0.1 to 0.5 seconds. FIG. 5 is a timing chart showing in detail the change state of each signal and the like in the droplet transfer period T1 of FIG.

<Droplet transfer period T1 (time ta (1) to time ta (n + 1))>
The droplet transfer period T1 is a period for transferring the droplet 151 from the consumable electrode 15 to the base material W while generating an arc a1 between the consumable electrode 15 and the base material W. At time ta (1) shown in FIGS. 4A and 5A, the operation control circuit 21 sends an operation control signal Ms for setting the robot moving speed VR to the speed v1 to the welding robot 1. Thereby, the robot moving speed VR with respect to the base material W of the welding torch 14 holding the consumable electrode 15 becomes v1. In this reference example, v1 = 0. Therefore, during the droplet transfer period T1, the welding torch 14 is stopped with respect to the base material W in the in-plane direction of the base material W. As shown in FIG. 5F, at time ta (1), the operation control circuit 21 sends the droplet transfer start signal Ss, the feed control circuit 38, the current switching circuit 313 of the output circuit 31, and the end determination circuit. 34 measurement circuits 341. Upon receiving the droplet transfer start signal Ss, the feed control circuit 38 sends a feed speed control signal Fc for setting the feed speed Fw to the speed fw1 to the feed mechanism 161. As a result, as shown in FIG. 5E, the consumable electrode 15 starts to be fed at the feeding speed Fw at the feeding speed Fw1. The feed speed Fw is positive in the direction from the welding torch 14 toward the base material W. The speed fw1 is, for example, 100 to 300 cm / min. As shown in FIG. 6H, at time ta (1), the pulse generation instruction signal Ps changes to the high level. As a result, the current waveform generation circuit 315 sends a current setting signal Ir1 for flowing the welding current Iw having a unit pulse waveform to the current switching circuit 313. Further, as shown in FIG. 4B, when the current switching circuit 313 receives the droplet transfer start signal Ss, the switch Sw in the current switching circuit 313 is connected to the a side. Therefore, a welding current Iw having a unit pulse waveform shown in FIG. 3C flows from time ta (1).

  As shown in FIG. 5C, the period Tf in which the welding current Iw having a unit pulse waveform flows is composed of an increase period Tu, a peak period Tp, a decrease period Td, and a base period Tb. In the increase period Tu, the welding current Iw increases to the peak current value ip. During the peak period Tp, the welding current Iw flows at the peak current value ip. In the decrease period Td, the welding current Iw decreases from the peak current value ip to the base current value ib. During the base period Tb, the welding current Iw flows at the base current value ib. In this reference example, the length of the base period Tb is adjusted so that the time average value of the welding voltage Vw becomes a preset voltage value vr1. Thereby, the length of the arc a1 is kept at an appropriate value. Then, the welding current Iw flows with the absolute value of the time average value at the first value ir1. In the peak period Tp, the droplet 151 grown at the tip of the consumable electrode 15 is affected by the electromagnetic pinch force. Then, the droplet 151 separates from the consumable electrode 15 and falls onto the base material W during the peak period Tp or the decrease period Td. Thus, one droplet 151 moves to the base material W during the period Tf.

  As shown in FIG. 5 (h), at time ta (2), the pulse generation instruction signal Ps again changes to the high level. As a result, the current waveform generation circuit 315 sends a current setting signal Ir1 for flowing the welding current Iw having a unit pulse waveform to the current switching circuit 313. Further, as shown in FIG. 2B, the switch Sw in the current switching circuit 313 is connected to the a side. Therefore, a welding current Iw having a unit pulse waveform shown in FIG. 5C flows from time ta (2). Similarly, a welding current Iw having a unit pulse waveform flows from time ta (3), ta (4)... Ta (n) (n is an integer). That is, in the droplet transfer period T1, a pulse current having a shape in which the unit pulse waveform is repeated a plurality of times flows. As shown in FIG. 6A, in the droplet transfer period T <b> 1, the droplet moves to the base material W and a molten pool 881 is formed in the base material W.

  During the droplet transfer period T1, the pulse generation instruction signal Ps is sent to the measurement circuit 341 in the end determination circuit 34. Further, as described above, the droplet transfer start signal Ss is sent to the measurement circuit 341 at time ta (1), which is the start time of the droplet transfer period T1. The measurement circuit 341 measures the number of times the pulse generation instruction signal Ps is received after the time when the droplet transfer start signal Ss is received. Thereby, the measurement circuit 341 measures the number Ns of peak periods Tp in each droplet transfer period T1. Then, when the number Ns reaches the set number Nb, the comparison circuit 342 sends an end instruction signal Es to the current switching circuit 313, the feed control circuit 38, and the operation control circuit 21 in the output circuit 31. In the present reference example, the comparison circuit 342 ends the end instruction signal at the time (time ta (n + 1)) after the period Tf from the time (time ta (n)) at which the number Ns has reached the set number Nb. Sending Es. The time at which the comparison circuit 342 sends the end instruction signal Es is not necessarily the time ta (n + 1), and may be before the time ta (n + 1). For example, the time at which the comparison circuit 342 sends the end instruction signal Es may be a time after the period Ts from the time (time ta (n)) when it is determined that the number Ns has reached the set number Nb. The set number Nb is, for example, 15-18.

<Cooling period T2>
The cooling period T2 is a period for cooling the molten pool 881 formed in the base material W. When the current switching circuit 313 receives the end instruction signal Es at time ta (n + 1), the switch Sw in the current switching circuit 313 is connected to the b side, as shown in FIGS. 4B and 5B. Thereby, the droplet transfer period T1 ends and the cooling period T2 starts. As shown in FIG. 6C, when the switch Sw in the current switching circuit 313 is connected to the b side, the welding current Iw flows with the second value ir2 as the time average value of the absolute value of the welding current Iw from the time ta (n + 1). In this reference example, the second value ir2 is a direct current. The second value ir2 is smaller than the first value ir1. The second value ir2 is a very small value such that the droplets do not migrate from the consumable electrode 15 to the base material W, and is, for example, 5 to 20A. In this reference example, the state where the arc a1 is generated in the cooling period T2 is continued. Therefore, it is not necessary to regenerate the arc a1 when starting the next droplet transfer period T1. On the other hand, as shown in FIGS. 4A and 5A, when the operation control circuit 21 receives the end instruction signal Es at time ta (n + 1), the operation for setting the robot moving speed VR to the speed v2. A control signal Ms is sent to the welding robot 1. As a result, the welding torch 14 holding the consumable electrode 15 moves at a speed v2 with respect to the base material W in the in-plane direction of the base material W along the welding progress direction Dr of FIGS. 6B and 7. start. The speed v2 is larger than the speed v1. The speed v2 is, for example, 50 to 150 cm / min. The welding direction Dr in each cooling period T2 is common to each other. As shown in FIG. 4E, when the feed control circuit 38 receives the end instruction signal Es, the feed control circuit 38 sends a feed speed control signal Fc for setting the feed speed Fw to the speed fw2 to the feed mechanism 161. Thereby, the consumable electrode 15 starts to be fed from the welding torch 14 toward the base material W at the speed fw2. The speed fw2 is smaller than the speed fw1, for example, 70 cm / min. As shown in FIG.6 (c), in the cooling period T2, the molten pool 881 is solidified by being cooled, and the circular welding trace 882 is formed by planar view (refer FIG. 7). When the welding torch 14 reaches a predetermined position of the base material W, the droplet transfer period T1 starts again as shown in FIG.

  As described above, welding is performed by repeating the droplet transfer period T1 and the cooling period T2. As a result, as shown in FIG. 7, a scaly bead is formed in which a plurality of circular welding marks 882 are continuous along the welding progress direction Dr.

  Next, the function and effect of this reference example will be described.

  In this reference example, when the number Ns of peak periods Tp in each droplet transition period T1 (the number of unit pulse waveforms of the welding current Iw) reaches the set number Nb, the droplet transition period T1 is terminated. Yes. One droplet 151 moves from the consumable electrode 15 to the base material W during the period Tf in which the welding current Iw having one unit pulse waveform flows. Therefore, the number of droplets 151 transferred in each droplet transfer period T1 can be made uniform. Moreover, the volume of the droplet 151 which transfers in each period Tf is substantially the same. Therefore, the size of each welding mark 882 formed on the base material W in each droplet transfer period T1 can be made uniform. Therefore, according to this reference example, a clean bead having a uniform width can be formed.

  In general, the period Tf, which is the period of the pulse generation instruction signal Ps sent by the signal generation circuit 316 that is a voltage frequency conversion circuit, is not a constant value but varies somewhat. Therefore, when the droplet transfer period T1 is controlled to have a certain length using the timer circuit, the number of times Ns in each droplet transfer period T1 may vary for each droplet transfer period T1. If the number of times Ns in each droplet transition period T1 varies, the number of droplets 151 that migrate in each droplet transition period T1 varies. Then, since the size of each welding mark 882 formed on the base material W in each droplet transfer period T1 varies, a clean bead having a uniform width cannot be formed. On the other hand, according to this reference example, as described above, the droplet transfer period T1 is terminated by measuring the number Ns of peak periods Tp in each droplet transfer period T1. Therefore, the number of times Ns in each droplet transfer period T1 does not vary. If the number of times Ns in each droplet transfer period T1 does not vary, the size of each welding mark 882 formed on the base material W in each droplet transfer period T1 can be made uniform as described above. Therefore, this reference example is suitable for forming a clean bead having a uniform width.

  Next, a second reference example of the present invention will be described with reference to FIG.

  FIG. 8 is a diagram showing an internal configuration of the arc welding system according to this reference example.

  An arc welding system A12 shown in FIG. 1 includes a welding robot 1, a robot control device 2, and a welding power source device 3. The arc welding system A12 is different from the above-described arc welding system A11 in that the measurement circuit 341 measures the number of times Ns, and the other points are the same. The measurement circuit 341 does not measure the number Ns of the peak period Tp based on the number of times the pulse generation instruction signal Ps is generated, but measures the number Ns based on the value of the welding current Iw detected by the current detection circuit 312. . Therefore, in this reference example, the current detection signal Id is sent from the current detection circuit 312 to the measurement circuit 341. The measurement circuit 341 employs, for example, the number of times Ns that the value of the welding current Iw exceeds a certain threshold value.

  According to the present reference example, a clean bead having a uniform width can be formed for the same reason as described in the first reference example.

  Next, a third reference example of the present invention will be described with reference to FIGS.

  FIG. 9 is a diagram showing an internal configuration of the arc welding system according to the present reference example. FIG. 10 is a timing chart of signals and the like in the welding method according to this reference example. FIG. 11 is a timing chart showing in detail the change state of each signal and the like in the droplet transfer period T1 of FIG.

  As shown in FIGS. 10 and 11, the present reference example differs from the first reference example in that the welding torch 14 is moved relative to the base material W while the arc a1 is extinguished during the cooling period T2. An arc welding system A13 shown in FIG. 9 includes a welding robot 1, a robot control device 2, and a welding power source device 3. Since the welding robot 1 and the robot controller 2 in the arc welding system A13 are the same as the arc welding system A11 according to the first reference example, description thereof is omitted. The welding power source device 3 includes an output circuit 31, a current value storage unit 37, an end determination circuit 34, a set number storage unit 35, and a feed control circuit 38. Each configuration of the welding power source device 3 is substantially the same as the configuration in the first reference example except for the output circuit 31 and the current value storage unit 37, and thus the description thereof is omitted.

  The current value storage unit 37 stores the third value ir3. The value of the third value ir3 is input from the teach pendant 23 and stored in the current value storage unit 37 via the operation control circuit 21, for example.

  The output circuit 31 includes a power supply circuit 311, a current detection circuit 312, a current error calculation circuit EI, a current switching circuit 313, a current control circuit 319, a current waveform generation circuit 315, a signal generation circuit 316, and a voltage detection. A circuit 317, a voltage error calculation circuit EV, and a voltage control circuit 318 are included. Each configuration of the output circuit 31 is substantially the same as the configuration in the first reference example except for the current control circuit 319, and thus the description thereof is omitted. The current control circuit 319 is for setting a value of a welding current Iw that flows during an arc generation period T0 described later. The current control circuit 319 sends a current setting signal Ir3 for allowing the welding current Iw to flow at the third value ir3 to the current switching circuit 313.

  Next, an arc welding method using the arc welding system A13 will be described with reference to FIGS. In the method according to this reference example, the arc generation period T0, the droplet transfer period T1, and the cooling period T2 are repeated.

<Arc generation period T0 (time tg1 to time ta (1))>
[Time tg1 to Time tg2]
The arc generation period T0 starts at time tg1. As shown in FIG. 11 (e), at time tg 1, the feed control circuit 38 sets the feed speed Fw as the feed speed control signal Fc to the value fw 3 (slow-down feed speed). To the feeding mechanism 161. As a result, the consumable electrode 15 is fed from the welding torch 14 with the feeding speed Fw as the value fw3. The value fw3 is, for example, 100 to 300 cm / min. At time tg1, since consumable electrode 15 and base material W are separated from each other, as shown in FIG. 5C, during a certain period from time tg1 (time tg1 to time tg2 in this reference example) The welding current Iw does not flow between the consumable electrode 15 and the base material W. On the other hand, as shown in FIG. 4D, from time tg1 to time tg2, a no-load voltage V0 of about 80 V, for example, is applied as the welding voltage Vw between the consumable electrode 15 and the base material W. The current control circuit 319 sends a current setting signal Ir3 to the current switching circuit 313. During time tg1 to time ta (1), the switch of the current switching circuit 313 is connected to the b side. Therefore, during time tg1 to time ta (1), the current setting signal Ir3 is sent from the current switching circuit 313 to the current error calculation circuit EI as the current setting signal Ir.

  Note that, as shown in FIG. 5A, in the arc generation period T0, the robot moving speed VR is 0, and the welding torch 14 does not move along the base material W.

[Time tg2 to Time tg3]
The consumable electrode 15 is fed from the welding torch 14 and approaches the base material W, and the consumable electrode 15 and the base material W come into contact at time tg2. Then, as shown in FIG. 11 (d), the welding voltage Vw applied between the consumable electrode 15 and the base material W rapidly decreases. Further, as shown in FIG. 3C, energization of the welding current Iw from the consumable electrode 15 to the base material W is started. As described above, the current setting signal Ir3 is sent from the current switching circuit 313 to the current error calculation circuit EI as the current setting signal Ir. Therefore, the value of the welding current Iw increases rapidly so as to become the third value ir3.

[Time tg3 to Time tg4]
As shown in FIG. 11C, at time tg3, the value of the welding current Iw reaches the third value ir3. And for a while from time tg3, the welding current Iw flows at the third value ir3. During a short period from time tg3 (time tg3 to time tg4 in this reference example), the consumable electrode 15 and the base material W are kept in contact with each other. While the consumable electrode 15 and the base material W are in contact, a portion of the consumable electrode 15 adjacent to the base material W is melted by Joule heat.

[Time tg4 to Time ta (1)]
At time tg4, a portion of the consumable electrode 15 that is close to the base material W is melted, and an arc a1 is generated between the consumable electrode 15 and the base material W. As shown in FIG. 11D, the welding voltage Vw applied between the consumable electrode 15 and the base material W increases rapidly in the vicinity of time tg4. From time tg4 to time ta (1), the welding current Iw is kept flowing at the third value ir3. This is because the distance between the consumable electrode 15 and the base material W is set to an appropriate length.

<Droplet transfer period T1 (time ta (1) to time ta (n + 1))>
The droplet transfer period T1 starts from time ta (1). As shown in FIGS. 10 (f) and 11 (f), at time ta (1), the operation control circuit 21 sends the droplet transfer start signal Ss to the feed control circuit 38 and the current switching circuit of the output circuit 31. 313 and the measurement circuit 341 of the end determination circuit 34. Thereafter, the same process as the process in the droplet transfer period T1 of the first reference example is performed.

  Also in this reference example, the pulse generation instruction signal Ps is sent to the measurement circuit 341 in the end determination circuit 34 during the droplet transfer period T1. Further, as described above, the droplet transfer start signal Ss is sent to the measurement circuit 341 at time ta (1), which is the start time of the droplet transfer period T1. The measurement circuit 341 measures the number of times the pulse generation instruction signal Ps is received after the time when the droplet transfer start signal Ss is received. Thereby, the measurement circuit 341 measures the number Ns of peak periods Tp in each droplet transfer period T1. Then, when the number of times Ns reaches the set number Nb, the comparison circuit 342 sends an end instruction signal Es to the current switching circuit 313, the feed control circuit 38, and the operation control circuit 21. The end instruction signal Es is also sent to the power supply circuit 31 (not shown).

<Cooling period T2>
The cooling period T2 is a period for cooling the molten pool 881 formed in the base material W. As shown in FIG. 11C and FIG. 11D, when the power supply circuit 311 receives the end instruction signal Es at time ta (n + 1), the power supply circuit 311 stops, and the welding voltage Vw and the welding current Iw are set. 0 (welding current Iw is caused to flow at second value ir2 = 0A). In this way, the droplet transfer period T1 ends and the cooling period T2 starts. As shown in FIG. 5E, when the feed control circuit 38 receives the end instruction signal Es, the feed control circuit 38 sends a feed speed control signal Fc for setting the feed speed Fw to 0 to the feed mechanism 161. Thereby, the supply of the consumable electrode 15 is stopped. As shown in FIGS. 10A and 11A, when the operation control circuit 21 receives the end instruction signal Es at time ta (n + 1), the operation control signal for setting the robot moving speed VR to the speed v2. Ms is sent to the welding robot 1. As a result, the welding torch 14 holding the consumable electrode 15 starts to move at a velocity v2 with respect to the base material W along the welding progress direction Dr (see FIGS. 6 and 7) in the in-plane direction of the base material W. . In the cooling period T2, the molten pool 881 is solidified by being cooled, and a circular welding mark 882 (see FIGS. 6 and 7) is formed in plan view. When the cooling period T2 ends, the arc generation period T0 described above is started and the arc a1 is generated again.

  As described above, in this reference example, welding is performed by repeating the arc generation period T0, the droplet transfer period T1, and the cooling period T2.

  According to the present reference example, a clean bead having a uniform width can be formed for the same reason as described in the first reference example.

  Next, a fourth reference example of the present invention will be described with reference to FIG.

  FIG. 12 is a diagram showing an internal configuration of the arc welding system according to this reference example.

  An arc welding system A14 shown in the figure includes a welding robot 1, a robot control device 2, and a welding power source device 3. The arc welding system A14 differs from the above-described arc welding system A13 in that the measurement circuit 341 measures the number Ns of times, and the other points are the same. The measurement circuit 341 does not measure the number Ns of the peak period Tp based on the number of times the pulse generation instruction signal Ps is generated, but measures the number Ns based on the value of the welding current Iw detected by the current detection circuit 312. . Therefore, in this reference example, the current detection signal Id is sent from the current detection circuit 312 to the measurement circuit 341. The measurement circuit 341 employs, for example, the number of times Ns that the value of the welding current Iw exceeds a certain threshold value.

  According to the present reference example, a clean bead having a uniform width can be formed for the same reason as described in the third reference example.

  Next, a fifth reference example of the present invention will be described.

  FIG. 13 is a diagram showing an internal configuration of an arc welding system according to a fifth reference example of the present invention.

  The arc welding system A21 shown in the figure has a function of automatically calculating the number of peak periods Tp (the number of unit pulses of the welding current Iw) that should be in one droplet transfer period T1, Mainly different from the arc welding system described above. This will be specifically described below.

  The arc welding system A21 includes a welding robot 1, a robot control device 2, and a welding power source device 3.

  Since the welding robot 1 in the arc welding system A21 is the same as the welding robot 1 in the arc welding system A11, the description thereof is omitted.

  The robot control device 2 includes an operation control circuit 21, a switching control circuit 22, and a teach pendant 23.

  The teach pendant 23 includes a display unit 231 and an operation unit 232. The display unit 231 displays, for example, parameters when performing welding. The operation unit 232 is for the user of the arc welding system A21 to input an instruction for starting welding or an instruction for changing the welding mode to the arc welding system A21. In this reference example, a main welding start instruction signal Ss1 is sent from the operation unit 232.

  The switching control circuit 22 is for controlling a mode of an end instruction circuit 346 described later. The switching control circuit 22 sends a first mode instruction signal Sm1 and a second mode instruction signal Sm2. As will be described later, when the first mode instruction signal Sm1 is sent from the switching control circuit 22, the end of the droplet transfer period T1 is determined based on the length of the droplet transfer period T1. On the other hand, when the second mode instruction signal Sm2 is sent from the switching control circuit 22, the end of the droplet transfer period T1 is the number Ns of peak periods Tp in the droplet transfer period T1 (the number of unit pulse waveforms of the welding current Iw). To be determined. The switching control circuit 22 does not need to have the configuration of the robot control device 2 and may have the configuration of the welding power source device 3.

  The welding power source device 3 includes an output circuit 31, a pulse number calculation circuit 32, a current value storage unit 33, an end determination circuit 34, a set number storage unit 35, a set time storage unit 36, and a feed control circuit 38. And including. The configurations of the output circuit 31, the current value storage unit 33, and the feed control circuit 38 in the welding power supply device 3 of the present reference example are the same as those in the arc welding system A11, and thus the description thereof is omitted. Hereinafter, the pulse number calculation circuit 32, the end determination circuit 34, the set number storage unit 35, and the set time storage unit 36 will be described.

  The set time storage unit 36 stores the set time Tr. The value of the set time Tr is input from the teach pendant 23 and stored in the set time storage unit 36 via the operation control circuit 21, for example.

  The pulse number calculation circuit 32 calculates the number of unit pulse waveforms to be included in the droplet transfer period T1. Specifically, the pulse number calculation circuit 32 calculates the standard pulse number Na. The standard pulse number Na is the number of peak periods Tp per set time Tr. In this reference example, the pulse number calculation circuit 32 receives an end instruction signal Es, a droplet transfer start signal Ss, and a pulse generation instruction signal Ps.

  The set number storage unit 35 stores the set number Nb. In this reference example, the set number storage unit 35 is connected to the pulse number calculation circuit 32, and the standard pulse number Na is sent from the pulse number calculation circuit 32. The set number storage unit 35 stores the standard pulse number Na obtained by the pulse number calculation circuit 32 as the set number Nb.

  The end determination circuit 34 is for determining whether or not to end the droplet transfer period T1. As illustrated in FIG. 14, the end determination circuit 34 includes a measurement circuit 341, a pulse number comparison circuit 342 ′, a time comparison circuit 344, and an end instruction circuit 346.

  The measuring circuit 341 is for measuring the number Ns of peak periods Tp in each droplet transition period T1 (that is, the number of unit pulse waveforms of the welding current Iw in each droplet transition period T1). In the present reference example, the measurement circuit 341 measures the number Ns of peak periods Tp based on the number of times the pulse generation instruction signal Ps is generated. Although description is omitted in this reference example, the measurement circuit 341 may perform measurement based on the value of the welding current Iw detected by the current detection circuit 312 as described regarding the arc welding system A12.

  When the number Ns of peak periods Tp in the droplet transfer period T1 reaches the set number Nb stored in the set number storage unit 35, the pulse number comparison circuit 342 'sends a set number arrival signal Sr2. In this reference example, the set number storage unit 35 stores the standard pulse number Na as the set number Nb. When the standard pulse number Na is stored as the set number Nb in the set number storage unit 35, the pulse number comparison circuit 342 ′ allows the number Ns of peak periods Tp in the droplet transfer period T1 to reach the standard pulse number Na. Then, the set number arrival signal Sr2 is sent.

  When the length of the droplet transfer period T1 reaches the set time Tr stored in the set time storage unit 36, the time comparison circuit 344 sends a set time arrival signal Sr1. In this reference example, the time comparison circuit 344 receives the droplet transfer start signal Ss. The time comparison circuit 344 determines the length of the droplet transfer period T1 by measuring the elapsed time from the time when the droplet transfer start signal Ss was received.

  The end instruction circuit 346 determines the end of the droplet transfer period T1 based on the length of the droplet transfer period T1, or the end of the droplet transfer period T1 is the number Ns of peak periods Tp in the droplet transfer period T1. To decide based on End instruction circuit 346 receives set time arrival signal Sr1, set number arrival signal Sr2, first mode instruction signal Sm1, and second mode instruction signal Sm2. When the termination instruction circuit 346 determines that the droplet transfer period T1 should be terminated, the termination instruction signal Es is sent to the output circuit 31 (current switching circuit 313 in this reference example), the operation control circuit 21, and the pulse number calculation circuit 32. The data is sent to the feed control circuit 38.

  The end instruction circuit 346 takes the first mode M1 and the second mode M2. When the end instruction circuit 346 receives the first mode instruction signal Sm1, the end instruction circuit 346 enters the first mode M1. In the case of the first mode M1, the end instruction circuit 346 sends an end instruction signal Es when it receives the set time arrival signal Sr1. On the other hand, when receiving the second mode instruction signal Sm2, the end instruction circuit 346 enters the second mode M2. In the case of the second mode M2, the end instruction circuit 346 sends an end instruction signal Es when it receives the set number arrival signal Sr2.

  Next, an arc welding method using the arc welding system A21 will be described with reference to FIG.

  Also in the arc welding method using the arc welding system A21, the droplet transfer period T1 and the cooling period T2 are alternately repeated as in the arc welding method using the arc welding system A11. The arc welding method using the arc welding system A21 uses the arc welding system A11 in that the end of the droplet transfer period T1 is determined based on the length of the droplet transfer period T1 for a certain period from the start of welding. Different from arc welding method.

<First mode period Tm1>
The first mode period Tm1 is a period during which the end instruction circuit 346 is in the first mode M1. First, when the user of the arc welding system A21 operates the operation unit 232 in the teach pendant 23, the main welding start instruction signal Ss1 is sent from the operation unit 232 to the operation control circuit 21 and the switching control circuit 22. When the operation control circuit 21 receives the main welding start instruction signal Ss1, after passing through a minute arc generation period (not shown in FIG. 15), the droplet transfer start signal Ss is determined as an output circuit 31, a pulse number calculation circuit 32, or an end determination. The droplet transfer period T1 starts, for example, by sending it to the circuit 34.

  As shown in FIG. 15, when the switching control circuit 22 receives the main welding start instruction signal Ss1, the switching control circuit 22 sends a first mode instruction signal Sm1 to the end instruction circuit 346 in the end determination circuit 34. When receiving the first mode instruction signal Sm1, the end instruction circuit 346 enters the first mode M1.

  The time comparison circuit 344 in the end determination circuit 34 measures the elapsed time from the time when the droplet transfer start signal Ss (see FIG. 5) is received. When the elapsed time from the time when the droplet transfer start signal Ss is received, that is, the length of the droplet transfer period T1 reaches the set time Tr, the time comparison circuit 344 sends the set time arrival signal Sr1 to the end instruction circuit 346. .

  Since the end instruction circuit 346 is in the first mode M1 as described above, the end instruction signal Es is sent to the output circuit 31 (current switching circuit 313 in the present reference example) when the set time arrival signal Sr1 is received. . When the output circuit 31 receives the end instruction signal Es, the droplet transfer period T1 ends and the cooling period T2 starts in the same manner as described for the arc welding system A11. Thus, during the first mode period Tm1, the end of the droplet transfer period T1 is determined based on the length of the droplet transfer period T1. That is, the time control process is performed in the first mode period Tm1.

  As described above, the droplet transfer period T1 and the cooling period T2 are alternately repeated.

<Calculation of standard pulse number>
During the first mode period Tm1, the pulse number calculation circuit 32 calculates the standard pulse number Na based on the set time Tr. In order to obtain the standard pulse number Na based on the set time Tr, the number of peak periods Tp in the droplet transfer period T1 whose length is the set time Tr may be used. An example of a method for calculating the standard pulse number Na by the pulse number calculation circuit 32 in this case is specifically as follows.

  In each droplet transfer period T1, the pulse number calculation circuit 32 receives the end instruction signal Es (see FIGS. 4 and 5) from the time at which the droplet transfer start signal Ss (see FIGS. 4 and 5) is received. The number of times the pulse generation instruction signal Ps has been received is measured. Thereby, the pulse number calculation circuit 32 measures the number Na (1), Na (2),... Na (m) (m is an integer) of the peak period Tp in each droplet transfer period T1. Na (m) is the number of peak periods Tp in the m-th droplet transfer period T1 counted from the start of welding. The maximum value of m is about 3 to 5, for example.

Next, the pulse number calculation circuit 32 obtains the average value of the number Na (1), Na (2),... Na (m) of the peak period Tp in each droplet transfer period T1, thereby obtaining the standard pulse number. Find Na. That is, the pulse number calculation circuit 32 calculates the standard pulse number Na based on the following equation.

Na = (Na (1) + Na (2) +... + Na (m)) / m

The pulse number calculation circuit 32 sends the standard pulse number Na thus determined to the set number storage unit 35. The set number storage unit 35 stores the standard pulse number Na as the set number Nb.

  In order to obtain the standard pulse number Na based on the set time Tr, the number of the peak period Tp in the droplet transfer period T1 whose length is the set time Tr is not used, but the unit pulse waveform in a droplet transfer period T1 is used. You may use the period of. An example of a method for calculating the standard pulse number Na by the pulse number calculation circuit 32 in this case is specifically as follows.

  In a droplet transfer period T1, the pulse number calculation circuit 32 measures a period for receiving the pulse generation instruction signal Ps (see FIG. 5). Thereby, the period Ttp (1), Ttp (2),... Ttp (m) (m is an integer) of the unit pulse waveform in a certain droplet transfer period T1 is measured. Ttp (m) is the period of the mth unit pulse waveform counted from the start of a certain droplet transfer period T1.

Next, the pulse number calculation circuit 32 divides the set time Tr by the average value of the periods Ttp (1), Ttp (2),. Ask for. That is, the pulse number calculation circuit 32 calculates the standard pulse number Na based on the following equation.

Na = m × Tr / (Ttp (1) + Ttp (2) +... + Ttp (m))

The pulse number calculation circuit 32 sends the standard pulse number Na thus determined to the set number storage unit 35. The set number storage unit 35 stores the standard pulse number Na as the set number Nb.

<Switching from the first mode period Tm1 to the second mode period Tm2>
In this reference example, when the switching control circuit 22 determines that the standard pulse number Na is obtained by the pulse number calculation circuit 32, the switching control circuit 22 sends the first mode instruction signal Sm1 to the end instruction circuit 346. Is switched to a state in which the second mode instruction signal Sm2 is sent to the end instruction circuit 346. Thereby, the end instruction circuit 346 switches from the first mode M1 to the second mode M2. The switching control circuit 22 determines that the standard pulse number Na is obtained by the pulse number calculation circuit 32, for example, a predetermined number of times (3, 4) from when the switching control circuit 22 receives the main welding start instruction signal Ss1. This is a case where a droplet transfer period T1 of about (times) has elapsed. Alternatively, the switching control circuit 22 determines that the standard pulse number Na is obtained by the pulse number calculation circuit 32, for example, when a predetermined time has elapsed since the switching control circuit 22 received the main welding start instruction signal Ss1. This is the case.

<Second mode period Tm2>
The second mode period Tm2 is a period during which the end instruction circuit 346 is in the second mode M2. During the second mode period Tm2, the pulse generation instruction signal Ps is sent to the measurement circuit 341 in the end determination circuit 34. The measurement circuit 341 measures the number of times the pulse generation instruction signal Ps is received after the time when the droplet transfer start signal Ss is received. Thereby, the measurement circuit 341 measures the number Ns of peak periods Tp in each droplet transfer period T1. Then, when the number Ns reaches the set number Nb (that is, the standard pulse number Na), the pulse number comparison circuit 342 ′ sends a set number arrival signal Sr2 to the end instruction circuit 346.

  In the second mode period Tm2, since the end instruction circuit 346 is in the second mode M2, when the set number arrival signal Sr2 is received, the end instruction signal Es is output to the output circuit 31 (in this reference example, the current switching circuit). 313). When the output circuit 31 receives the end instruction signal Es, the droplet transfer period T1 ends and the cooling period T2 starts in the same manner as described for the arc welding system A11. Thus, in the second mode period Tm2, the end of the droplet transfer period T1 is determined based on the number of peak periods Tp (number of unit pulse waveforms) in the droplet transfer period T1. That is, the pulse number control step is performed in the second mode period Tm2.

  As described above, the droplet transfer period T1 and the cooling period T2 are alternately repeated.

  Next, the function and effect of this reference example will be described.

  According to the present reference example, a clean bead having a uniform width can be formed in the second mode period Tm2 for the same reason as described regarding the arc welding system A11.

  In general, some users of the arc welding system A21 have knowledge about the length of the droplet transfer period T1, but have knowledge about the number of peak periods Tp included in the droplet transfer period T1. There are those who have not. For users who do not have knowledge about the number of peak periods Tp (number of unit pulse waveforms) included in the droplet transfer period T1, it is very difficult to set the value of the set number Nb. Further, in this case, welding for knowing the desired set number Nb has to be performed many times, and there is a possibility that a lot of wasted base material is generated.

  In this reference example, the pulse number calculation circuit 32 calculates the standard pulse number Na based on the set time Tr. The standard pulse number Na is the number of peak periods Tp per set time Tr (number of unit pulse waveforms). According to such a configuration, if the user of the arc welding system A21 has knowledge about the set time Tr, the pulse number calculation circuit 32 may determine the standard pulse number Na based on the set time Tr that the user has knowledge. As described above, the number of peak periods Tp to be included in the set time Tr can be obtained. Therefore, even when a user who does not have knowledge about the number of times of the peak period Tp included in the droplet transfer period T1 uses the arc welding system A21, an appropriate setting is made using the standard pulse number Na. The value of the number Nb is determined. Therefore, an arc welding system that is easy to use for many users is realized.

  In this reference example, the pulse number calculation circuit 32 sends the standard pulse number Na to the set number storage unit 35. The set number storage unit 35 stores the standard pulse number Na obtained by the pulse number calculation circuit 32 as the set number Nb. According to such a configuration, the standard pulse number Na obtained by the pulse number calculation circuit 32 can be automatically stored in the set number storage unit 35 as the set number Nb. Therefore, it is not necessary for the user to set the setting number Nb. This configuration is easy for the user to use.

  In this reference example, the switching control circuit 22 sends the first mode instruction signal Sm1 when receiving the main welding start instruction signal Ss1 from the operation unit 232. Further, when the switching control circuit 22 determines that the standard pulse number Na has been obtained by the pulse number calculation circuit 32, the switching control circuit 22 sends the second mode instruction signal Sm2. According to such a configuration, from the start of the main welding until the standard pulse number Na is obtained by the pulse number calculation circuit 32 (first mode period Tm1), the droplets that many users have knowledge about. The droplet transfer period T1 ends based on the length of the transfer period T1. Therefore, it is avoided that the circular welding mark formed from the start of the main welding until the standard pulse number Na is obtained by the pulse number calculation circuit 32 becomes extremely large or extremely small. can do. In this reference example, the switching control circuit 22 sends the second mode instruction signal Sm2 when determining that the standard pulse number Na is obtained by the pulse number calculation circuit 32. Therefore, the second mode period Tm2 is automatically started without the user operating the operation unit 232 or the like. Therefore, the second mode period Tm2 can be started smoothly without delay.

  In addition, during the second mode period Tm2, the switching control circuit 22 changes from the state of sending the second mode instruction signal Sm2 when the length of the droplet transfer period T1 becomes a value outside the predetermined range. You may switch to the state which sends 1 mode instruction | indication signal Sm1. According to such a configuration, when the length of the droplet transfer period T1 is extremely long or short, the end of the droplet transfer period T1 is again determined based on the length of the droplet transfer period T1. Can do. Then, after the new standard pulse number Na is calculated, the switching control circuit 22 may be configured to switch to a state in which the second mode instruction signal Sm2 is sent. Note that the standard pulse number Na obtained by the pulse calculation circuit 32 may be displayed on the teach pendant 23.

  Next, a first embodiment of the present invention will be described.

  An arc welding system A22 shown in FIG. 16 includes a welding robot 1, a robot control device 2, and a welding power source device 3.

  Since the welding robot 1 in the arc welding system A22 is the same as the welding robot 1 in the arc welding system A11, the description thereof is omitted.

  The robot control device 2 includes an operation control circuit 21, a switching control circuit 22, and a teach pendant 23.

  The teach pendant 23 includes a display unit 231 and an operation unit 232. In the present embodiment, the display unit 231 displays the standard pulse number Na obtained by the pulse number calculation circuit 32. In the present embodiment, a main welding start instruction signal Ss1 and a preliminary welding start instruction signal Ss2 are sent from the operation unit 232. The display unit 231 and the operation unit 232 are the same as those described with respect to the arc welding system A21 in other respects.

  The switching control circuit 22 is substantially the same as that in the arc welding system A21. However, the process in which the switching control circuit 22 sends the first mode instruction signal Sm1 and the second mode instruction signal Sm2 is different from that in the arc welding system A21.

  Since the welding power source device 3 is the same as that in the arc welding system A21, the description thereof is omitted. In the present embodiment, the pulse number calculation circuit 32 is not connected to the set number storage unit 35. Therefore, the setting number storage unit 35 receives the value of the setting number Nb from the teach pendant 23 and stores it via the operation control circuit 21.

  Next, the arc welding method using arc welding system A22 is demonstrated using FIG.

<First mode period Tm1>
First, when the user of the arc welding system A22 operates the operation unit 232 in the teach pendant 23, a preliminary welding start instruction signal Ss2 is sent from the operation unit 232 to the operation control circuit 21 and the switching control circuit 22. When the operation control circuit 21 receives the preliminary welding start instruction signal Ss2, the operation control circuit 21 calculates the droplet transfer start signal Ss after the minute arc generation period (not shown in FIG. 17), and the number of pulses is calculated. The droplet transfer period T1 starts by sending it to the circuit 32, the end determination circuit 34, or the like.

  When the switching control circuit 22 receives the preliminary welding start instruction signal Ss2, the switching control circuit 22 sends the first mode instruction signal Sm1 to the end instruction circuit 346 in the end determination circuit 34. When receiving the first mode instruction signal Sm1, the end instruction circuit 346 enters the first mode M1. In the first mode period Tm1 in which the end instruction circuit 346 is in the first mode M1, the end of the droplet transfer period T1 is determined based on the length of the droplet transfer period T1, as described for the arc welding system A21. Is done.

  As described above, the droplet transfer period T1 and the cooling period T2 are alternately repeated.

<Calculation of standard pulse number>
Also in the present embodiment, during the first mode period Tm1, the pulse number calculation circuit 32 calculates the standard pulse number Na as described for the arc welding system A21. Since the method for obtaining the standard pulse number Na is as described above, the description thereof is omitted. In the present embodiment, the obtained standard pulse number Na is displayed on the display unit 231.

  Then, after the standard pulse number Na is obtained, the arc between the consumable electrode 15 and the base material W is extinguished, and the welding of the base material W is once ended. Thus, the first mode period Tm1 ends.

<Second mode period Tm2>
Next, a base material W different from the base material W used in the first mode period Tm1 is newly prepared. The newly prepared base material W is made of the same material as the base material W used in the first mode period Tm1 and has the same thickness.

  The user of the arc welding system A22 inputs the standard pulse number Na displayed on the display unit 231 to the teach pendant 23. As a result, the standard pulse number Na is stored as the set number Nb in the set number storage unit 35 via the operation control circuit 21 and the like.

<Second mode period Tm2>
Next, when the user of the arc welding system A22 operates the operation unit 232 in the teach pendant 23, a main welding start instruction signal Ss1 is sent from the operation unit 232 to the operation control circuit 21 and the switching control circuit 22. When the operation control circuit 21 receives the main welding start instruction signal Ss1, the operation control circuit 21 calculates the droplet transfer start signal Ss after the minute arc generation period (not shown in FIG. 17) passes, and the number of pulses calculated. The droplet transfer period T1 starts by sending it to the circuit 32, the end determination circuit 34, or the like.

  In the present embodiment, when the switching control circuit 22 receives the main welding start instruction signal Ss1, the second mode instruction signal Sm2 is sent to the end instruction circuit 346 in the end determination circuit 34. Upon receiving the second mode instruction signal Sm2, the end instruction circuit 346 enters the second mode M2. In the second mode period Tm2 in which the end instruction circuit 346 is in the second mode M2, as described with respect to the arc welding system A21, the end of the droplet transfer period T1 is the number of times of the peak period Tp in the droplet transfer period T1. Determined based on Ns.

  Next, the effect of this embodiment is demonstrated.

  According to the present embodiment, a clean bead having a uniform width can be formed in the second mode period Tm2 for the same reason as described for the arc welding system A11.

  In the present embodiment, the pulse number calculation circuit 32 calculates the standard pulse number Na based on the set time Tr. The standard pulse number Na is the number of peak periods Tp per set time Tr (number of unit pulse waveforms). According to such a configuration, if the user of the arc welding system A21 has knowledge about the set time Tr, the pulse number calculation circuit 32 may determine the standard pulse number Na based on the set time Tr that the user has knowledge. As described above, the number of peak periods Tp to be included in the set time Tr can be obtained. Therefore, even when a user who does not have knowledge about the number of times of the peak period Tp included in the droplet transfer period T1 uses the arc welding system A22, an appropriate setting is made using the standard pulse number Na. The value of the number Nb is determined. Therefore, an arc welding system that is easy to use for many users is realized.

  In the present embodiment, when receiving the preliminary welding start instruction signal Ss2 from the operation unit 232, the switching control circuit 22 sends the first mode instruction signal Sm1 and the main welding start instruction signal Ss1 from the operation unit 232. When received, the second mode instruction signal Sm2 is sent. According to such a configuration, the second mode period Tm2 starts when the switching control circuit 22 receives the main welding start instruction signal Ss1. Therefore, after obtaining the standard pulse number Na in the first mode period Tm1, welding is performed on a new base material W different from the base material W used in the first mode period Tm1 in the second mode period Tm2. It can be carried out. Therefore, from the first point of welding to the new base material W, the end of the droplet transfer period T1 is based on whether the number Ns of peak periods Tp in the droplet transfer period T1 has reached the standard pulse number Na. Can be determined. Therefore, the entire width of the beads formed on the new base material W can be made uniform.

  Next, a second embodiment of the present invention will be described.

  An arc welding system A23 shown in FIG. 18 includes a welding robot 1, a robot control device 2, and a welding power source device 3.

  This embodiment is different from the arc welding system A21 in that a preliminary welding start instruction signal Ss2 is sent from the operation unit 232 in addition to the main welding start instruction signal Ss1. The switching control circuit 22 is different from the arc welding system A21 in that the preliminary welding non-execution mode and the preliminary welding execution mode are taken. According to the arc welding system A23, any of the arc welding method described regarding the arc welding system A21 and the arc welding method described regarding the arc welding system A22 can be performed.

  When the switching control circuit 22 is in the preliminary welding non-execution mode, a process similar to the process in the switching control circuit 22 of the arc welding system A21 is executed. That is, in the preliminary welding non-execution mode, the switching control circuit 22 sends the first mode instruction signal Sm1 when receiving the main welding start instruction signal Ss1 from the operation unit 232, and the pulse number calculation circuit 32 When it is determined that the standard pulse number Na is obtained, the second mode instruction signal Sm2 is sent.

  On the other hand, when the switching control circuit 22 is in the preliminary welding execution mode, a process similar to the process in the switching control circuit 22 of the arc welding system A22 is executed. That is, when the switching control circuit 22 is in the preliminary welding execution mode, the first mode instruction signal Sm1 is sent when the preliminary welding start instruction signal Ss2 from the operation unit 232 is received, and the main welding from the operation unit 232 is performed. When the start instruction signal Ss1 is received, the second mode instruction signal Sm2 is sent.

  According to such a configuration, both of the advantages in the arc welding system A21 and the advantages in the arc welding system A22 can be enjoyed.

  In the arc welding method using the arc welding systems A21, A22, A23, a configuration in which the arc a1 is extinguished during the cooling period T2 as described regarding the arc welding systems A13, A14 may be adopted.

  The scope of the present invention is not limited to the embodiment described above. The specific configuration of each part of the present invention can be changed in various ways. In the above description, the voltage frequency conversion circuit is described as the signal generation circuit. However, the signal generation circuit may be a circuit in which an integration circuit and a comparison circuit are combined. In the above description, an example in which the unit pulse waveform is a direct current has been described, but an alternating current having an EN period may be used.

A11, A12, A13, A14, A21, A22, A23 Arc welding system 1 Welding robot 11 Base member 12 Arm 13 Motor 14 Welding torch 15 Consumable electrode 151 Droplet 16 Wire feeding device 161 Feeding mechanism 19 Coil liner 2 Robot control Device 21 Operation control circuit 22 Switching control circuit 23 Teach pendant 231 Display unit 232 Operation unit 3 Welding power supply device 31 Output circuit 311 Power supply circuit 312 Current detection circuit 313 Current switching circuit 314 Current control circuit 315 Current waveform generation circuit 316 Signal generation circuit 317 Voltage detection circuit 318 Voltage control circuit 319 Current control circuit 32 Pulse number calculation circuit 33 Current value storage unit 34 End determination circuit 341 Measurement circuit 342 Comparison circuit 342 ′ Pulse number comparison circuit 344 Time comparison circuit 346 End indication circuit 35 Setting number storage 36 Setting time storage unit 37 Current value storage unit 38 Feed control circuit 881 Weld pool Dr. Welding trace Dr Welding direction EI Current error calculation circuit Ei Current error signal EV Voltage error calculation circuit Ev Voltage error signal Es End instruction signal Fc Speed control signal Fw Feeding speed IB Base current storage unit ib Base current value IBR Current control circuit ibr Current setting signal Id Current detection signal IP Peak current storage unit ip Peak current value IPR Current control circuit ipr Current setting signal Ir, Ir1, Ir2 , Ir3 Current setting signal ir1 First value ir2 Second value Iw Welding current M1 First mode M2 Second mode Ms Operation control signal Na Standard pulse number Nb Set number Ns Number of times Ps Pulse generation instruction signal Sm1 First mode instruction signal Sm2 First 2 mode instruction signal Sr1 set time arrival signal Sr2 set number arrival signal Ss Drop transfer start signal Ss1 Main welding start instruction signal Ss2 Preliminary welding start instruction signal SW switching circuit T0 Arc generation period T1 Droplet transfer period T2 Cooling period Tm1 First mode period Tm2 Second mode period TB Base period storage unit TD Reduction period storage Part Td Decrease period TM Timer circuit TP Peak period storage part Tp Peak period Tr Set time tss Period signal Ts Period TU Increase period storage part Tu Increase period Vd Voltage detection signal VR Robot moving speed Vr Voltage setting signal Vw Welding voltage W Base material

Claims (1)

Comprising a droplet transfer period a pulse current to the vanishing Worn electrodes, a cooling period for cooling the molten pool formed in the base material after the droplet transfer period, the output circuit a plurality of times, respectively,
The waveform of the pulse current is an arc welding system having a shape that repeats a unit pulse waveform including a peak period in which current flows at a peak value and a base period in which current flows at a base value smaller than the peak value,
A set time storage unit for storing the set time;
A set number storage unit for storing the set number;
Based on the set time, a pulse number calculation circuit for calculating a standard pulse number that is the number of times of the peak period per set time;
When the number of times of the peak period in the droplet transfer period reaches the set number, an end determination circuit that sends an end instruction signal;
A switching control circuit for sending a first mode instruction signal and a second mode instruction signal,
The termination determination circuit is
When the length of the droplet transfer period reaches the set time, a time comparison circuit for sending a set time arrival signal,
When the number of peak periods in the droplet transfer period reaches the set number, a pulse number comparison circuit that sends a set number arrival signal;
An end instruction switching circuit,
The end instruction switching circuit enters the first mode when receiving the first mode instruction signal, enters the second mode when receiving the second mode instruction signal,
The end instruction switching circuit sends the end instruction signal when receiving the set time arrival signal in the first mode, and receives the set number arrival signal in the second mode. Send the end instruction signal,
The arc welding system, wherein the output circuit ends the droplet transfer period when receiving the end instruction signal.

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