JP2004202546A - Laser irradiation arc start control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser irradiation arc start control method for constantly performing excellent arc start. <P>SOLUTION: In the laser irradiation arc start control method, when a welding start signal is inputted, a welding wire 1 is fed forward to a work 2 while laser beam irradiation is stopped. At the point of time when the welding wire 1 is brought into contact with the work 2, the initial current IS of the predetermined small value is conducted from a welding power source device, the welding wire 1 is fed backward from the work 2, and the traveling instruction signal of a working head is outputted. When the welding wire 1 is separated from the work 2 by the backward feed, the initial arc 3a is generated, the backward-feed is continued while maintaining the state of generating the initial arc 3a. After the predetermined time elapsed from the time when the initial arc 3a is generated, the welding wire 1 is fed forward again to the work 2 at a predetermined regular feeding speed WS to conduct the regular welding current IW, and laser irradiation is started. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention irradiates a laser to a welding target position on a workpiece or a peripheral portion thereof, starts feeding a welding wire and outputs a welding voltage, and generates an arc between the welding wire and the workpiece. The present invention relates to a laser irradiation arc start control method.
[0002]
[Prior art]
[Prior art 1]
In welding using only consumable electrode gas shielded arc welding, the wire feed motor is rotated forward to feed the welding wire forward to the workpiece, and then when it is determined that the welding wire has come into contact with the workpiece, the wire is fed. The welding wire is reversely fed by rotating the motor in the reverse direction, and at the same time, an initial current of a small current value is supplied.If an initial arc is generated by the backward feeding, the welding wire is fed forward again at a steady feeding speed. An arc start control method for simultaneously starting an arc by applying a steady welding current has been conventionally known (for example, see Patent Document 1).
Hereinafter, the arc start control method of the prior art 1 will be described with reference to FIGS.
[0003]
FIG. 1 is a schematic diagram showing a welding wire feed system for explaining an arc start control method according to Prior Art 1. In the figure, a welding wire 1 is fed through a welding torch 4 by a feed roll 5a directly connected to a wire feed motor WM. When the wire feed motor WM rotates forward, the welding wire 1 is fed forward to the workpiece 2, and when the wire feed motor WM rotates reversely, the welding wire 1 is fed backward from the workpiece 2. The welding voltage Vw from the welding power supply PS is supplied to the welding wire by the contact tip 4 a attached to the tip of the welding torch 4.
[0004]
Next, an arc start control method according to Prior Art 1 will be described. FIG. 2 is a diagram for explaining an arc start control method according to the related art 1. In the figure, when a welding start signal is input from the outside to the welding power source device PS, the welding wire 1 is fed forward to the workpiece 2 at the initial feeding speed as shown in FIG. At the same time, a no-load voltage is applied between the welding wire 1 and the workpiece 2 as the welding voltage Vw. The distance between the tip of the wire and the workpiece 2 is gradually reduced by the above-described forward feeding.
[0005]
Next, as shown in FIG. 2B, when it is determined that the welding wire 1 has come into contact with the workpiece 2 by forward feeding, the welding wire 1 is fed backward from the workpiece 2. At the same time, an initial current having a small current value is supplied.
[0006]
Next, as shown in FIG. 2C, when the welding wire 1 and the workpiece 2 are separated by the backward feeding, an initial arc 3a through which the above-described initial current Is flows is generated. It is determined that the initial arc 3a has occurred, and during the predetermined time, the backward feeding is continued while maintaining the initial arc occurrence state 3a as shown in FIG. Therefore, the distance Lw between the tip of the wire and the workpiece is gradually increased.
[0007]
Next, after the elapse of the predetermined time, the welding wire 1 is again fed forward to the workpiece 2 at a steady feeding speed. At the same time, a steady welding current of a large current corresponding to the steady feeding speed is supplied. Accordingly, the state shifts from the initial arc generation state 3a shown in FIG. 3D to the steady arc generation state 3b shown in FIG.
[0008]
[Prior art 2]
Next, there is known a combined laser irradiation arc welding method in which laser irradiation with a YAG laser, a carbon dioxide laser, a semiconductor laser, or the like, and consumable electrode gas shield arc welding are used in combination. In this welding method, high-speed welding of 2 to 5 [m / min] can be performed by irradiating a laser having high energy to the arc generating portion. In addition, this welding method irradiates a laser to a welding target position on a workpiece to be welded or a peripheral portion thereof at the start of welding, and at the same time, starts welding wire feeding and welding voltage output, thereby smoothly forming an arc. Can be generated.
[0009]
In this laser irradiation arc welding method, the feeding of the welding wire and the output of the welding voltage are started while the laser irradiation is stopped, and when the welding wire comes into contact with the workpiece, the feeding of the welding wire is stopped and the welding wire is stopped. The laser irradiation is started at the same time as the prescribed initial current is supplied, and after the initial arc at which the initial current is supplied by the laser irradiation is generated, the re-feeding of the welding wire is started and the steady welding current is supplied. A laser irradiation arc start control method for smoothly transitioning from an initial arc generation state to a steady arc generation state has been proposed (for example, see Patent Document 2).
Hereinafter, the related art 2 will be described with reference to FIGS. 3 to 5.
[0010]
FIG. 3 is a view showing a general laser irradiation arc welding apparatus, and FIG. 4 is an enlarged view of the processing head shown in FIG. 3 and 4, a processing head 8 including a welding torch 4 and a laser torch 12 is attached to a wrist of a manipulator 6, and a welding wire wound on a wire reel 15 is supplied to the welding torch 4 by a wire feeding device 16. Will be sent. Reference numeral 13 denotes a robot controller for controlling the manipulator 6, and reference numeral 14 denotes a teach pendant for operating the manipulator 6.
Further, the welding power supply device PS controls the rotation of the welding wire feeding roll of the wire feeding device 16 and supplies electric power between the power supply tip in the welding torch 4 and the workpiece to be welded, so that the welding wire and the welding wire are connected to each other. An arc is generated between the workpiece and the workpiece.
[0011]
The laser light output from the laser oscillation device 9 is transmitted to the laser torch 12 by the optical fiber 11, and is converged by a lens provided in the laser torch 12 so that the object to be welded is focused, and is irradiated on the object to be welded. Is done.
[0012]
FIG. 5 is a diagram for explaining a laser irradiation arc start control method according to Prior Art 2. This will be described with reference to FIG. When a welding start signal is input from the robot control device 13 to the welding power supply device PS and the laser oscillation device 9, the welding wire 1 is initially fed while the laser irradiation is stopped, as shown in FIG. Sent at speed. At the same time, a no-load voltage is applied between the welding wire 1 and the workpiece 2.
[0013]
Next, when the welding wire 1 comes into contact with the workpiece 2 by feeding, as shown in FIG. 2B, a laser 7 is irradiated and an initial current is supplied. At the same time, the feeding of the welding wire 1 is stopped.
Then, as time elapses, the plasma existing space 7a is formed by the laser irradiation, and when the leading end of the welding wire 1 whose feeding is stopped by the application of the initial current is melted and separated from the workpiece 2, As shown in FIG. 3C, an initial arc 3a is generated.
When the initial arc 3a is generated, the welding wire 1 is fed at a constant feeding speed. At the same time, a steady welding current corresponding to the steady feed speed is supplied.
[0014]
At the time when several hundred [ms] to several [s] have passed since the initial arc 3a was generated, the welding wire 1 was fed at a steady feeding speed as shown in FIG. A steady arc 3b through which a steady welding current flows is generated.
[0015]
[Prior art 3]
In order to more reliably generate a steady arc, a laser irradiation arc start control method combining the above-described prior art 1 and prior art 2 has been proposed. FIG. 6 is a diagram for explaining a laser irradiation arc start control method according to Prior Art 3. This will be described with reference to FIG.
When a welding start signal is input from the robot control device 13 to the welding power supply device PS and the laser oscillation device 9, the welding wire 1 is initially fed while the laser irradiation is stopped, as shown in FIG. Sent at speed. At the same time, a no-load voltage is applied between the welding wire 1 and the workpiece 2.
[0016]
Next, when the welding wire 1 comes into contact with the workpiece 2 by feeding, as shown in FIG. 2B, a laser 7 is irradiated, and the welding wire 1 is fed back from the workpiece 2. At the same time, an initial current having a small current value is supplied.
[0017]
Next, as shown in FIG. 3C, when the welding wire 1 and the workpiece 2 are not brought into contact with each other due to the backward feeding, an initial arc 3a through which the above initial current is applied is generated. It is determined that the initial arc 3a has occurred, and during the predetermined time, the backward feeding is continued while maintaining the initial arc occurrence state 3a as shown in FIG. Therefore, the distance Lw between the tip of the wire and the workpiece is gradually increased.
[0018]
Next, after the elapse of the predetermined time, the welding wire 1 is again fed forward to the workpiece 2 at a steady feeding speed. At the same time, a steady welding current of a large current corresponding to the steady feeding speed is supplied. Accordingly, the state shifts from the initial arc generation state 3a shown in FIG. 3D to the steady arc generation state 3b shown in FIG.
[0019]
[Patent Document 1]
JP-A-2002-178145
[Patent Document 2]
JP-A-2002-248571
[0020]
[Problems to be solved by the invention]
In the laser irradiation arc start control method of the above-mentioned conventional technology 3, when the work to be welded is a thin plate, since the laser is irradiated prior to the arc, welding defects such as burn-through may occur.
[0021]
An object of the present invention is to provide a laser irradiation arc start control method capable of always performing a good arc start.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is:
Laser irradiation for irradiating a laser to a welding target position on a workpiece or a peripheral portion thereof, starting feeding of a welding wire and outputting a welding voltage, and generating an arc between the welding wire and the workpiece. In the arc start control method, when the welding start signal is input, the welding wire is forwardly fed to the workpiece while the laser irradiation is stopped, and is predetermined at the time when the welding wire comes into contact with the workpiece. The welding current is supplied from the welding power supply device and the welding wire is started to retreat from the work to be welded, and at the same time, a traveling command signal for a machining head including a laser torch and a welding torch is output, and the retreat feeding is performed. When the welding wire separates from the workpiece, an initial arc through which the initial current flows is generated, and the initial arc is maintained while maintaining the initial arc generation state. The reciprocating feed is continued, and after a lapse of a predetermined time from the time when the initial arc is generated, the welding wire is forwardly fed again to the work to be welded at a predetermined steady feeding speed, and the steady feeding is performed. A laser irradiation arc start control method, characterized in that a steady welding current corresponding to a feed rate is supplied and laser irradiation is started.
[0023]
The invention described in claim 2 is
2. The laser irradiation according to claim 1, wherein the laser irradiation is started after a lapse of a predetermined time from the start of forward feeding of the welding wire to the workpiece again at a predetermined steady feeding speed. Is a laser irradiation arc start control method.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described based on examples with reference to the drawings.
[Embodiment 1]
FIG. 7 is a block diagram of a welding power supply device for implementing the laser irradiation arc start control method of the present invention. Hereinafter, each circuit block will be described with reference to FIG.
[0025]
Voltage detection circuit VD detects welding voltage Vw and outputs voltage detection signal Vd. The short-circuit / arc discrimination circuit SA receives the voltage detection signal Vd as input, and outputs a short-circuit signal when the welding wire 1 and the workpiece 2 are in contact with each other, an arc-generation signal when the arc is in an arc-generating state, It is output as a short circuit / arc determination signal Sa. The delay circuit DT outputs a delay signal Dt that becomes High level for a predetermined delay time Td, triggered by the change of the short-circuit / arc determination signal Sa from the short-circuit signal to the arc generation signal.
[0026]
The steady feed speed setting circuit WS outputs a steady feed speed setting signal Ws. When the welding start signal St is input from the robot controller 13, the feed control circuit FC feeds the welding wire 1 to the workpiece 2 at an initial feed speed Wfi corresponding to a predetermined initial feed speed set value Wi. When the forward feeding is performed and the short-circuit / arc discrimination signal Sa subsequently becomes the short-circuit signal, the backward feeding speed corresponding to the predetermined backward feeding speed set value Wr from the workpiece 2 to the welding wire 1 is returned. When the output of the delay signal Dt is completed, the welding wire 1 is again fed to the workpiece 2 at a steady feed speed corresponding to the steady feed speed setting signal Ws. A feed control signal Fc for forward feeding at Wfs is output. The wire feed motor WM feeds the welding wire 1 forward or backward according to the feed control signal Fc, as described above in the description of FIG.
[0027]
Voltage setting circuit VS outputs voltage setting signal Vs for setting welding voltage Vw of welding power supply PS. The output control circuit INV outputs a welding voltage Vw and a welding current Iw suitable for maintaining the arc 3 stably by inverter control, thyristor phase control, or the like, using a commercial power supply as an input. The output control circuit INV supplies a predetermined small current value of the initial current Is from when the welding start signal St is input from the robot controller 13 to when the output of the delay signal Dt ends. A constant voltage characteristic corresponding to the voltage setting signal Vs for forming a constant current characteristic or a drooping characteristic for energizing, and thereafter supplying a steady welding current Iw corresponding to the value of the steady feeding speed setting signal Ws. To form
[0028]
The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The steady-state current determination circuit SID receives the current detection signal Id, and outputs a steady-state arc generation signal Sid (High level) when it determines that the steady-state current has been supplied based on the current value.
[0029]
The arc-laser synchronizing circuit 10 receives the above-described steady arc generation signal Sid and outputs a laser output start signal Lst (High level) to the laser oscillation device 9. For example, a high-speed operation programmable controller may be used as the arc-laser synchronization circuit 10 in order to almost eliminate the time delay from the occurrence of the steady arc to the irradiation of the laser. Further, a delay circuit is provided in the arc / laser synchronizing circuit 10, and after a predetermined time has elapsed from the input of the steady arc generation signal Sid, the laser output start signal Lst (High level) is oscillated by the laser. The data may be output to the device 9.
[0030]
The robot controller 13 receives the short-circuit / arc discrimination signal Sa, and outputs a machining head traveling command signal Hst for starting traveling of the machining head to the manipulator 6 when the signal becomes a short-circuit signal.
[0031]
FIG. 8 is a timing chart of each signal of the welding power supply device PS described above with reference to FIG. FIG. 7A shows the time change of the welding start signal St, FIG. 7B shows the time change of the feed control signal Fc, and FIG. 8C shows the change of the short circuit / arc discrimination signal Sa. FIG. 4D shows a time change of the delay signal Dt, FIG. 4E shows a time change of the welding current Iw, and FIG. FIG. 7G shows the time change of the laser output start signal Lst, and FIG. 7H shows the time change of the machining head travel command signal Hst. FIGS. (I1) to (I5) show the feeding state of the welding wire 1 at each time. Hereinafter, description will be made with reference to FIG.
[0032]
{Circle around (1)} When a welding start signal St is input from the robot control device 13 to the welding power supply PS in the period t1 between the times t1 and t2 as shown in FIG. Thus, the feed control signal Fc becomes the positive initial feed speed set value Wi, and the welding wire 1 is fed forward to the workpiece 2 at the initial feed speed Wfi as shown in FIG. Is done. When the feed control signal Fc has a positive value, forward feed is performed, and when the feed control signal Fc has a negative value, reverse feed is performed.
At the same time, as described above in the description of FIG. 7, the output control circuit INV forms a constant current characteristic or a drooping characteristic, and although not shown, a no-load voltage is applied as the welding voltage Vw.
Next, during the period from the time t1 to the time t2, the distance Lw between the wire tip and the work to be welded is gradually reduced by the forward feeding as shown in FIG.
[0033]
{Circle around (2)} In the period t2 between the times t2 and t3, when the welding wire 1 comes into contact with the workpiece 2 by the forward feeding as shown in FIG. 12 (I2), a short circuit occurs as shown in FIG. The / arc discrimination signal Sa changes to a short circuit signal (High level). When the short circuit / arc discrimination signal Sa changes to a short circuit signal, the feed control signal Fc becomes a negative value of the backward feed speed set value Wr, as shown in FIG. 2, the sheet is fed backward at the backward feeding speed Wfr.
At the same time, as shown in FIG. 9E, the initial current Is having a small current value is supplied by the constant current characteristic or the drooping characteristic described in the item (1). The reason for setting the value of the initial current Is to a small current value of about 50 [A] is to prevent the welding wire 1 from being melted by the initial current Is and welding to the workpiece 2.
Further, at time t2, when the welding wire 1 comes into contact with the workpiece 2, the robot controller 13 outputs a machining head travel command signal Hst to the manipulator 6, as shown in FIG. Thereafter, the processing head 8 actually starts running near a time t4 described later due to a mechanical response delay of the manipulator 6.
[0034]
Next, during the period from time t2 to time t3, the welding wire 1 is fed backward, but the response delay time of the forward / reverse reversal of the wire feeding motor WM described above with reference to FIG. The welding wire 1 and the workpiece 2 remain in contact with each other due to the time required for the backward feeding of the play due to the bending in the welding wire 1. Therefore, as shown in FIG. 2F, the distance Lw between the wire tip and the workpiece remains at 0 [mm] during this period.
[0035]
{Circle around (3)} At time t3 from time t3 to time t4, when the welding wire 1 and the workpiece 2 are separated by the backward feeding as shown in FIG. An arc 3a occurs. The occurrence of the initial arc 3a is determined, and the short circuit / arc determination signal Sa changes from the short circuit signal (High level) to the arc generation signal (Low level) as shown in FIG. With this change as a trigger, the delay signal Dt is output (High level) for a predetermined delay time Td (time t3 to t4) as shown in FIG.
During the backward feed time Tr from time t3 to t4 when the above-mentioned delay signal Dt is output, as shown in FIG. (I4), the backward feed is continued while the initial arc occurrence state 3a is maintained. I do. Therefore, as shown in FIG. 2F, the distance Lw between the tip of the wire and the workpiece is gradually increased.
[0036]
{Circle around (4)} During the period from time t4 to time t5, when the output of the delay signal Dt is completed as shown in FIG. 4D, the feed control signal Fc becomes positive as shown in FIG. The value becomes the steady-state feed speed setting signal Ws, and the welding wire 1 is again fed forward to the workpiece 2 at the steady-state feed speed Wfs. At the same time, as described above in the description of FIG. 7, the output control circuit INV forms a constant voltage characteristic and supplies a large current steady welding current Iw corresponding to the steady feed speed Wfs.
Further, as shown in FIG. 2F, the distance Lw between the wire tip and the work to be welded is calculated from the distance Lwt [mm] between the wire tip and the work to be welded at the time t4 at the time of re-advancing feeding. At the time t5 after the convergence time Tc1 [s] elapses due to the application of the steady welding current Iw, the arc converges to the steady arc length (steady distance between the wire tip and the workpiece) Lwc [mm]. Therefore, during this period, the state shifts from the initial arc generation state 3a shown in FIG. (I4) to the steady arc generation state 3b shown in FIG. (I5).
[0037]
According to the experiments performed by the inventors, the laser irradiation arc start control method of the present invention described above was performed when the work to be welded was a thin plate. As a result, the weld pool generated by the arc can be irradiated with the laser. Good arc start could be performed without occurrence of welding defects such as burn-through.
[0038]
【The invention's effect】
The present invention is configured as described above, and has the following effects.
[0039]
The present invention irradiates a laser to a welding target position on a workpiece or a peripheral portion thereof, starts feeding a welding wire and starts outputting a welding voltage, and forms an arc between the welding wire and the workpiece. In the laser irradiation arc start control method to be generated, when a welding start signal is input, the welding wire is fed forward to the workpiece while the laser irradiation is stopped, and the welding wire comes into contact with the workpiece. A running command signal of a processing head including a laser torch and a welding torch is output while energizing an initial current of a predetermined small current value from the welding power supply device at the time and starting backward feeding of the welding wire from the workpiece. When the welding wire is separated from the work to be welded by the backward feeding, an initial arc in which the initial current is applied is generated and the initial arc generating state is maintained. Until the predetermined time has elapsed from the time when the initial arc is generated, and the welding wire is forward-forward-fed to the workpiece again at a predetermined steady-state feeding speed. A laser welding arc start control method, characterized in that a steady welding current corresponding to the feeding speed is supplied and the laser irradiation is started.
By carrying out this method, the laser can be irradiated to the molten pool generated by the arc, so that a good arc start can be performed without occurrence of welding defects such as burn-through.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a welding wire feeding system for explaining an arc start control method according to Prior Art 1. FIG.
FIG. 2 is a diagram for explaining an arc start control method according to Prior Art 1.
FIG. 3 is a view showing a general laser irradiation arc welding apparatus.
FIG. 4 is an enlarged view of the processing head shown in FIG.
FIG. 5 is a diagram for explaining a laser irradiation arc start control method according to Prior Art 2.
FIG. 6 is a diagram for explaining a laser irradiation arc start control method according to Prior Art 3;
FIG. 7 is a block diagram of a welding power supply device for implementing the laser irradiation arc start control method of the present invention.
8 is a timing chart of each signal of the welding power supply device PS described above with reference to FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Welding wire 2 Workpiece 3 Arc 3a Initial arc (generation state)
3b Arc (generation state)
4 Welding Torch 4a Contact Tip 5a Feed Roll 6 Manipulator 7a Plasma Presence Space 7 Laser 8 Processing Head 9 Laser Oscillator 10 Arc / Laser Synchronization Circuit 11 Optical Fiber 12 Laser Torch 13 Robot Controller 14 Teach Pendant 15 Wire Reel 16 Wire Feed Device DT Delay circuit Dt Delay signal FC Feed control circuit Fc Feed control signal Hst Machining head traveling command signal ID Current detection circuit Id Current detection signal INV Output control circuit Is Initial current Iw Welding current Lst Laser output start signal Lw Wire tip Welding object distance Lwt Wire tip and welding object distance PS Welding power supply SA Arc discrimination circuit Sa Arc discrimination signal Sid Steady arc generation signal SID Steady current discrimination circuit St Welding start signal Tc1 Convergence time Td Delay time Tr Reverse feed Time VD Pressure detection circuit Vd Voltage detection signal VS Voltage setting circuit Vs Voltage setting signal Vw Welding voltage Wfi Initial feed speed Wfr Reverse feed speed Wfs Feed speed Wi Initial feed speed set value WM Wire feed motor Wr Reverse feed speed setting Value WS Feeding speed setting circuit Ws Feeding speed setting signal

Claims (2)

Laser irradiation for irradiating a laser to a welding target position on a workpiece or a peripheral portion thereof, starting feeding of a welding wire and outputting a welding voltage, and generating an arc between the welding wire and the workpiece. In the arc start control method, when the welding start signal is input, the welding wire is forwardly fed to the workpiece while the laser irradiation is stopped, and is predetermined at the time when the welding wire comes into contact with the workpiece. The welding current is supplied from the welding power supply device and the welding wire is started to retreat from the work to be welded, and at the same time, a traveling command signal for a machining head including a laser torch and a welding torch is output, and the retreat feeding is performed. When the welding wire separates from the workpiece, an initial arc through which the initial current flows is generated, and the initial arc is maintained while maintaining the initial arc generation state. The reciprocating feed is continued, and after a lapse of a predetermined time from the time when the initial arc is generated, the welding wire is forwardly fed again to the work to be welded at a predetermined steady feeding speed, and the steady feeding is performed. A laser irradiation arc start control method, characterized in that a steady welding current corresponding to a feed rate is supplied and the laser irradiation is started. 2. The laser irradiation according to claim 1, wherein the laser irradiation is started after a lapse of a predetermined time from the start of forward feeding of the welding wire to the workpiece again at a predetermined steady feeding speed. Laser irradiation arc start control method.

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