JP5053481B2 - Arc start control method and welding power source apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc start control method for consumable electrode gas shielded arc welding in which a welding wire is fed forward and backward to a workpiece to be arced by a wire feeding motor capable of forward and reverse rotation.
[0002]
[Prior art]
The wire feed motor is rotated forward to feed the welding wire forward to the work piece. When it is determined that the welding wire has contacted the work piece, the wire feed motor is reversely rotated to move the welding wire backward. At the same time, an initial current Is having a small current value is energized, and when an initial arc is subsequently generated by backward feeding, the welding wire is fed forward again at a steady feeding speed Wfs, and at the same time, a steady welding current Iw is energized. An arc start control method for consumable electrode gas shielded arc welding for arc starting is known. Hereinafter, this arc start control method of the prior art will be described with reference to FIGS.
[0003]
FIG. 2 is a schematic diagram showing a welding wire feeding system. The welding wire 1 is fed through the welding torch 4 by a feeding roll 5a directly connected to the wire feeding motor WM. When the wire feed motor WM is rotated forward, the welding wire 1 is fed forward to the workpiece 2 and when it is rotated reversely, the welding wire 1 is fed backward from the workpiece 2. The welding voltage Vw from the welding power supply device PS is fed to the welding wire by the contact tip 4a attached to the tip of the welding torch 4. Further, the shortest distance between the tip of the welding wire 1 and the workpiece 2 is the distance Lw [mm] between the tip of the wire and the workpiece.
[0004]
FIG. 3 is a block diagram of a welding power source apparatus for carrying out the above-described conventional arc start control method. Hereinafter, each circuit block will be described with reference to FIG.
[0005]
The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The short circuit / arc discriminating circuit SA receives the voltage detection signal Vd as described above and outputs a short circuit signal when the welding wire 1 and the work piece 2 are in contact with each other, an arc generation signal when the arc is generated, It outputs as a short circuit / arc discrimination signal Sa. The delay circuit DT outputs a delay signal Dt that is at a 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.
[0006]
The steady feeding speed setting circuit WS outputs a steady feeding speed setting signal Ws. When the welding start signal St is input from the outside, the feed control circuit FC feeds the welding wire 1 forward to the workpiece 2 at an initial feed speed Wfi corresponding to a predetermined initial feed speed set value Wi. Then, when the short-circuit / arc determination signal Sa becomes a short-circuit signal, the welding wire 1 is moved backward from the work piece 2 at a reverse feed speed Wfr corresponding to a predetermined reverse feed speed set value Wr. When the output of the delay signal Dt is completed, the welding wire 1 is fed forward again to the work piece 2 at a steady feeding speed Wfs corresponding to the steady feeding speed setting signal Ws. A feed control signal Fc 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.
[0007]
The voltage setting circuit VS outputs a voltage setting signal Vs for setting the welding voltage Vw of the welding power source device PS. The output control circuit INV receives a commercial power supply and outputs a welding voltage Vw and a welding current Iw suitable for stably maintaining the arc 3 by inverter control, thyristor phase control, or the like. The output control circuit INV is a constant current characteristic that energizes an initial current Is having a predetermined small current value from the time when the welding start signal St is input from the outside to the time when the output of the delay signal Dt is ended. Alternatively, a drooping characteristic is formed, and thereafter, a constant voltage characteristic corresponding to the voltage setting signal Vs for applying the steady welding current Iw corresponding to the value of the steady feeding speed setting signal Ws is formed.
[0008]
FIG. 4 is a timing chart of each signal of the welding power source apparatus PS described above with reference to FIG. FIG. 4A shows the change over time of the welding start signal St, FIG. 4B shows the change over time of the feed control signal Fc, and FIG. 4C shows the short-circuit / arc discrimination signal Sa. (D) shows the time change of the delay signal Dt, (E) shows the time change of the welding current Iw, (F) shows the wire tip, The time change of the distance Lw between to-be-welded objects is shown, The same figure (G1)-(G5) has shown the supply state of the welding wire 1 in each time. Hereinafter, a description will be given with reference to FIG.
[0009]
(1) Period from time t1 to t2
When a welding start signal St is input from the outside at time t1, as shown in FIG. 10A, the feed control signal Fc is a positive initial feed speed as shown in FIG. The set value Wi is set, and the welding wire 1 is fed forward to the work piece 2 at the initial feeding speed Wfi as shown in FIG. When the feed control signal Fc is a positive value, forward feeding is performed, and when the feed control signal Fc is negative, backward feeding is performed. At the same time, as described above in the description of FIG. 3, 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, as shown in FIG. 4F, the distance Lw between the wire tip and the workpiece is gradually shortened by the above-described forward feeding.
[0010]
(2) Period from time t2 to t3
At time t2, when the welding wire 1 comes into contact with the work piece 2 by forward feeding as shown in (G2) of the figure, as shown in (C) of FIG. High level). When the short circuit / arc discrimination signal Sa changes to a short circuit signal, the feed control signal Fc becomes a negative reverse feed speed set value Wr as shown in FIG. 2 is reversely fed at a reverse feed speed Wfr. At the same time, as shown in FIG. 5E, the initial current Is having a small current value is applied 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 being welded to the work piece 2.
Next, during the period from the time t2 to the time t3, the welding wire 1 is fed backward, but within the welding torch of the welding wire 1 and the response delay time of forward / reverse inversion 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 depending on the time required for the backward feeding of the play due to the bend. Therefore, as shown in FIG. 5F, the wire tip-to-be-welded distance Lw remains 0 [mm] during this period.
[0011]
(3) Period from time t3 to t4
At time t3, as shown in FIG. 3G3, when the welding wire 1 and the workpiece 2 are not brought into contact with each other by backward feeding, an initial arc 3a in which the initial current Is is applied is generated. When it is determined that the initial arc 3a has occurred, 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 feeding time Tr from the time t3 to t4 when the delay signal Dt is output, the backward feeding is continued while maintaining the initial arc generation state 3a as shown in FIG. To do. Therefore, as shown in FIG. 5F, the distance Lw between the wire tip and the workpiece is gradually increased.
[0012]
(4) Period from time t4 to t5
When the output of the delay signal Dt is completed at time t4 as shown in FIG. 4D, the feed control signal Fc is a positive feed speed setting signal having a positive value, as shown in FIG. The welding wire 1 is fed forward again to the workpiece 2 at a steady feeding speed Wfs. At the same time, as described above in the description of FIG. 3, the output control circuit INV forms a constant voltage characteristic and energizes a steady welding current Iw having a large current corresponding to the steady feeding speed Wfs.
Further, as shown in FIG. 8F, the wire tip-to-be-welded object distance Lw is calculated from the wire tip-to-be-welded object distance Lwt [mm] at the time of re-forward feeding at time t4. The current is converged to a steady arc length (steady wire tip-to-be-welded distance) Lwc [mm] at time t5 after the convergence time Tc1 [s] has elapsed by energizing the steady welding current Iw. Therefore, during this period, a transition is made from the initial arc generation state 3a shown in FIG. 4G4 to the steady arc generation state 3b shown in FIG.
[0013]
[Problems to be solved by the invention]
The above-described conventional arc start control method has the following two problems to be solved for smoothly shifting from the initial arc generation state to the steady arc generation state.
(1) First problem to be solved
As described above with reference to FIG. 4, during the period of backward feeding at the backward feeding speed Wfr (time t <b> 3 to t <b> 4), the arc break is generated without recontacting the welding wire and the workpiece. Therefore, it is necessary to continue the backward feeding while maintaining the initial arc generation state stably. The reason is that if the contact is made again after the initial arc is generated, there is a high possibility that the welding wire and the workpiece are welded, and therefore, the arc cannot be started. In addition, when an arc break occurs during this period, no arc is generated for a long time until the welding wire comes into contact with the workpiece again by re-forward feeding, and as a result, the bead appearance of the arc start portion becomes poor. Because.
[0014]
In order to prevent the re-contact, it is necessary to increase the backward feed speed Wfr in order to quickly increase the distance Lw between the wire tip and the workpiece after the initial arc is generated. On the other hand, in order not to cause the arc break, the maximum value of the reverse feed speed Wfr is limited according to the type of shield gas, the diameter of the welding wire, the thickness of the workpiece, and the like. Therefore, it is necessary to set the reverse feed speed Wfr to an appropriate value that does not cause re-contact or arc breakage according to the type of shield gas, the diameter of the welding wire, the thickness of the workpiece, and the like. For example, when the type of shield gas is carbon dioxide 100 [%], arc breakage is more likely to occur than in the case of a mixed gas of carbon dioxide 20 [%] + argon gas 80 [%]. It is necessary to slow down the feeding speed Wfr.
[0015]
However, as described above with reference to FIG. 4, in the conventional technique, the delay time Td for performing the reverse feed is a constant value. Therefore, if the setting of the reverse feed speed Wfr is changed for the reason described above, the re-forward feed is consequently performed. The distance Lwt between the wire tip and the work piece at that time changes. If the difference between the wire tip-to-be-welded distance Lwt and the steady arc length Lwc at the time of re-forward feeding is increased by this change, the convergence time required for the transition from the initial arc generation state to the steady arc generation state Since Tc1 becomes long, there is a problem that the bead appearance of the arc start portion is deteriorated.
[0016]
(2) Second problem to be solved
The steady arc length Lwc shown in FIG. 4 (F) described above is set to an appropriate value by the voltage setting signal Vs according to the type of shield gas, the steady feed speed Wfs, the plate thickness of the workpiece, and the like. . Therefore, in order to shorten the convergence time Tc1 required for the transition from the initial arc generation state to the steady arc generation state and improve the bead appearance of the arc start portion, the difference from the above-mentioned steady arc length Lwc is small. Thus, it is necessary to control the distance Lwt between the wire tip and the workpiece during re-advance feeding to an appropriate value according to the type of shielding gas, the steady feeding speed Wfs, the thickness of the workpiece, and the like.
[0017]
However, in the prior art, the delay time Td is a constant value when the backward feed speed Wfr is determined to be an appropriate value for the reason of the above item (1). The inter-object distance Lwt is a constant value and cannot be controlled to an arbitrary value. Therefore, in the prior art, even if the setting of the steady arc length Lwc changes, the distance Lwt between the wire tip and the workpiece to be welded at the time of re-forward feeding cannot be controlled accordingly. There is a problem that it cannot be prevented that the convergence time Tc1 is increased and the bead appearance of the arc start portion is deteriorated due to the increase in the convergence time Tc1.
[0018]
[Means for Solving the Problems]
According to the first aspect of the present invention, when a welding start signal is input, the welding wire is forwardly fed to the workpiece, and is predetermined when the welding wire contacts the workpiece. Does not melt the welding wire An initial current having a small current value is energized from the welding power source device, and the welding wire is retracted from the workpiece, and the initial current is energized when the welding wire is separated from the workpiece by the backward feeding. While the initial arc is generated and the initial arc generation state is maintained, the backward feeding is continued, and when the distance between the wire tip and the work piece reaches a predetermined backward distance set value, the welding wire is From the initial arc generating state to the steady arc generating state by feeding forward to the workpiece again at a predetermined steady feeding speed and energizing a steady welding current corresponding to the steady feeding speed. Make a smooth transition,
The distance between the wire tip and the workpiece to be welded has reached the set value for the backward distance by the backward feeding, and the welding wire backward distance obtained by integrating the feeding speed of the backward feeding from the initial arc occurrence time is This is an arc start control method for consumable electrode gas shielded arc welding, which is determined by reaching the setback distance.
[0019]
According to the second aspect of the present invention, when a welding start signal is inputted, the welding wire is forwardly fed to the workpiece, and is predetermined when the welding wire contacts the workpiece. Does not melt the welding wire An initial current having a small current value is energized from the welding power source device, and the welding wire is retracted from the workpiece, and the initial current is energized when the welding wire is separated from the workpiece by the backward feeding. While the initial arc is generated and the initial arc generation state is maintained, the backward feeding is continued, and when the distance between the wire tip and the work piece reaches a predetermined backward distance set value, the welding wire is From the initial arc generating state to the steady arc generating state by feeding forward to the workpiece again at a predetermined steady feeding speed and energizing a steady welding current corresponding to the steady feeding speed. Make a smooth transition,
That the distance between the wire tip and the work piece has reached the set value for the reverse distance by the reverse feed, the time for the reverse feed from the time of the initial arc occurrence is the set value for the reverse distance and the reverse feed. This is an arc start control method for consumable electrode gas shielded arc welding, which is determined by reaching the set value for the reverse feed time determined in accordance with the feed speed set value.
[0022]
According to a third aspect of the present invention, a wire feed motor that feeds a welding wire forward or backward from a workpiece to be welded and a short circuit when the welding wire and the workpiece are in contact with each other. When the signal is in an arc generation state, a short circuit / arc determination circuit that outputs the arc generation signal as a short circuit / arc determination signal, and a distance when the distance between the wire tip and the workpiece to be welded is equal to a predetermined receding distance setting signal value When a welding start signal is input, a distance determination circuit that outputs a coincidence signal and the welding wire is fed forward to the workpiece, and when the short circuit / arc determination signal becomes a short circuit signal, the welding wire is A backward distance feed control circuit for feeding backward from the workpiece and feeding the welding wire forward again to the workpiece at a predetermined steady feeding speed when the distance coincidence signal is output; , Start welding No. is between the time entered to the point where the distance match signal is output a predetermined Does not melt the welding wire An output control circuit that forms a constant current characteristic or a drooping characteristic that energizes an initial current of a small current value and thereafter forms a constant voltage characteristic that energizes a steady welding current corresponding to the steady feeding speed. And
When the welding start signal is input, the welding wire is fed forward, and when the short circuit / arc discrimination signal becomes a short circuit signal, the initial current is energized, the welding wire is fed backward, and the backward movement is performed. When the welding wire is separated from the work piece by feeding, an initial arc in which the initial current flows is generated, and the backward feeding is continued while maintaining the initial arc generation state, and the distance coincidence signal is output. At that time, the welding wire is forwardly fed again at a steady feeding speed and the steady welding current is energized to smoothly transition from the initial arc generation state to the steady arc generation state.
Feeding that outputs the distance coincidence signal when the distance of the welding wire, which is obtained by integrating the feeding speed of the backward feeding from the time when the initial arc occurs, reaches the value of the backward distance setting signal It is a welding power supply apparatus for consumable electrode gas shield arc welding which is a speed integration circuit.
[0023]
According to a fourth aspect of the present invention, a wire feed motor that feeds a welding wire forward or backward from a workpiece to be welded and a short circuit when the welding wire and the workpiece are in contact with each other. When the signal is in an arc generation state, a short circuit / arc determination circuit that outputs the arc generation signal as a short circuit / arc determination signal, and a distance when the distance between the wire tip and the workpiece to be welded is equal to a predetermined receding distance setting signal value When a welding start signal is input, a distance determination circuit that outputs a coincidence signal and the welding wire is fed forward to the workpiece, and when the short circuit / arc determination signal becomes a short circuit signal, the welding wire is A backward distance feed control circuit for feeding backward from the workpiece and feeding the welding wire forward again to the workpiece at a predetermined steady feeding speed when the distance coincidence signal is output; , Start welding No. is between the time entered to the point where the distance match signal is output a predetermined Does not melt the welding wire An output control circuit that forms a constant current characteristic or a drooping characteristic that energizes an initial current of a small current value and thereafter forms a constant voltage characteristic that energizes a steady welding current corresponding to the steady feeding speed. And
When the welding start signal is input, the welding wire is fed forward, and when the short circuit / arc discrimination signal becomes a short circuit signal, the initial current is energized, the welding wire is fed backward, and the backward movement is performed. When the welding wire is separated from the work piece by feeding, an initial arc in which the initial current flows is generated, and the backward feeding is continued while maintaining the initial arc generation state, and the distance coincidence signal is output. At that time, the welding wire is forwardly fed again at a steady feeding speed and the steady welding current is energized to smoothly transition from the initial arc generation state to the steady arc generation state.
The distance discriminating circuit is set to the value of the reverse feed time setting signal that is determined in accordance with the reverse distance setting signal and the reverse feed speed setting value from the initial arc occurrence time. It is a welding power supply device for consumable electrode gas shield arc welding, which is a reverse feed timer circuit that outputs the distance coincidence signal when the distance is reached.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
An example of an embodiment of the present invention is shown in FIG. 1 (the same diagram as FIG. 6),
When the welding start signal St is input, the welding wire 1 is fed forward to the workpiece 2;
When the welding wire 1 contacts the workpiece 2, an initial current Is having a predetermined small current value is energized from the welding power source device PS and the welding wire 1 is moved backward from the workpiece 2.
When the welding wire 1 is separated from the workpiece 2 by the backward feeding, an initial arc 3a in which the initial current Is is energized is generated, and the backward feeding is continued while maintaining the initial arc generation state 3a. ,
When the distance Lw between the wire tip and the workpiece reaches a predetermined setback distance Ls, the welding wire 1 is fed forward again to the workpiece 2 at a predetermined steady feeding speed Wfs. Arc start control method for consumable electrode gas shielded arc welding that smoothly transitions from the initial arc generation state 3a to the steady arc generation state 3b by applying a steady welding current Iw corresponding to the steady feeding speed Wfs. It is.
[0027]
【Example】
[Example 1]
The invention of Example 1 described below is It is the Example used as the foundation of this invention. In the invention of the first embodiment, the distance Lwt between the wire tip and the workpiece to be welded at the time of re-advance feeding described above can be set to an appropriate value corresponding to the steady arc length Lwc by a backward distance setting signal Ls described later. . The invention of Example 1 will be described below.
[0028]
FIG. 5 is a block diagram of a welding power source apparatus for carrying out the arc start control method of the first embodiment. In this figure, the same circuit blocks as those in FIG. 3 described above are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, the reverse distance setting circuit LS, the distance determination circuit LD, the reverse distance feed control circuit FCR, and the output control circuit INV, which are circuit blocks different from those in FIG. 3 surrounded by a dotted line, will be described with reference to FIG.
[0029]
The receding distance setting circuit LS outputs a receding distance setting signal Ls set corresponding to the steady arc length Lwc described above with reference to FIG. The distance discrimination circuit LD outputs a distance coincidence signal Ld when the distance Lw between the wire tip and the workpiece is equal to the value of the retreat distance setting signal Ls. As a method for detecting the distance Lw between the wire tip and the workpiece, the thyristor phase control is performed by the method described later in Embodiments 2 to 4, and when the output control circuit INV described above is inverter controlled, the PWM control pulse width is used. In this case, there is a method of performing by the firing phase angle. As in the case of FIG. 3, the reverse distance feed control circuit FCR corresponds to a predetermined initial feed speed setting value Wi when the welding wire 1 is input to the work piece 2 when a welding start signal St is input from the outside. Forward feed at the initial feed speed Wfi, and when the short-circuit / arc discrimination signal Sa becomes a short-circuit signal, the welding wire 1 is equivalent to the reverse feed speed set value Wr set in advance from the workpiece 2. Unlike the case of FIG. 3, when the distance matching signal Ld is output, the welding wire 1 is again sent to the work piece 2 at a steady feeding speed setting signal Ws. A feed control signal Fc for feeding forward at a steady feed speed Wfs corresponding to is output. The output control circuit INV is a constant current characteristic that energizes the initial current Is having a predetermined small current value from the time when the welding start signal St is input from the outside to the time when the distance coincidence signal Ld is output. Alternatively, a drooping characteristic is formed, and thereafter, a constant voltage characteristic corresponding to the voltage setting signal Vs for energizing the steady welding current Iw corresponding to the value of the steady feeding speed setting signal Ws is formed.
[0030]
FIG. 6 is a timing chart of each signal in the welding power source apparatus PS of the first embodiment described above. FIG. 4A shows the change over time of the welding start signal St, FIG. 4B shows the change over time of the feed control signal Fc, and FIG. 4C shows the short-circuit / arc discrimination signal Sa. FIG. 4D shows the time change of the distance coincidence signal Ld, FIG. 4E shows the time change of the welding current Iw, and FIG. 4F shows the wire tip. -The time change of the distance Lw between to-be-welded objects is shown, The same figure (G1)-(G5) has shown the supply state of the welding wire 1 in each time. The operation in the period from the time t1 to the time t3 in the figure is the same as the operation at the same time in FIG. The operation at time t41 in FIG. 4 corresponding to time t4 in FIG. 4 and operation at time t51 in FIG. 4 corresponding to time t5 in FIG. 4 will be described below with reference to FIG.
[0031]
Period from time t41 to t51
At time t41, as shown in FIG. 5F, when the distance Lw between the wire tip and the workpiece is made equal to the value of the backward distance setting signal Ls by the backward feeding at the backward feeding speed Wfr, As shown in (D), the distance coincidence signal Ld is output (High level). When the distance coincidence signal Ld is output, the feed control signal Fc becomes the value of the steady feed speed setting signal Ws, and the welding wire 1 has the steady feed speed Wfs as shown in FIG. Then, it is fed forward again to the work piece 2. At the same time, the output control circuit INV described above with reference to FIG. 5 forms a constant voltage characteristic and energizes a steady welding current Iw having a large current value corresponding to the steady feeding speed Wfs.
Further, as shown in FIG. 4F, the wire tip-to-be-welded distance Lw is equal to the value of the backward distance setting signal Ls at time t41. The distance Lwt [mm] is obtained, and the steady arc length Lwc [mm] is obtained at time t51. At this time, as described above, the backward distance setting signal Ls is set to a value substantially equal to the steady arc length Lwc. Thus, the difference from the steady arc length Lwc becomes smaller and the convergence time Tc2 is shorter than the convergence time Tc1 in the prior art of FIG. Therefore, the transition from the initial arc generation state 3a shown in (G4) to the steady arc generation state 3b shown in (G5) is smoothly performed in a short time.
[0032]
[Example 2]
The invention of Example 2 described below is Corresponding to the inventions of claim 1 and claim 3 . In the invention of the second embodiment, the fact that the distance Lw between the wire tip and the workpiece to be welded has reached the value of the backward distance setting signal Ls by the backward feeding described in the description of the first embodiment, from the initial arc occurrence time point. This is the arc start control method according to the first embodiment, in which the welding wire retraction distance Lr obtained by integrating the retraction feed speed Wfr reaches the above retreat distance setting value Ls. The invention of Example 2 will be described below.
[0033]
FIG. 7 is a block diagram of a welding power source apparatus for carrying out the arc start control method of the second embodiment. In this figure, the same circuit blocks as those in FIG. 5 described above are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, a feed speed detection circuit WD and a feed speed integration circuit IW, which are circuit blocks different from those in FIG. 5 surrounded by a dotted line, will be described with reference to FIG.
[0034]
The feed speed detection circuit WD detects the feed speed Wf and outputs a feed speed detection signal Wd. As a detection method, a method of detecting an encoder by attaching an encoder to the wire feed motor WM and detecting by an output signal of the encoder, a method of detecting by an armature voltage of the wire feed motor WM proportional to the feed speed Wf, etc. are commonly used. Yes.
The feed speed integrating circuit IW is a circuit that replaces the distance discriminating circuit LD described above with reference to FIG. 5, and during the reverse feed period from when the short circuit / arc discrimination signal Sa changes from the short circuit signal to the arc generation signal. The distance coincidence signal Ld is output when the welding wire receding distance Lr obtained by integrating the feed speed detection signal Wd reaches the value of the receding distance setting signal Ls. The integrated value of the reverse feed speed Wfr from the above initial arc occurrence time (when the short circuit / arc determination signal Sa changes from the short circuit signal to the arc generation signal) is the welding wire regardless of the set value of the reverse feed speed Wfr. The distance Lw between the wire tip and the workpiece to be welded, which is the retreat distance of.
Moreover, since the timing chart of each signal in the welding power source device PS of the second embodiment described above is the same as that of FIG. 6 described above, the description thereof is omitted.
[0035]
[Example 3]
The invention of Example 3 described below is Corresponding to the inventions of claim 2 and claim 4 . In the invention of the third embodiment, the fact that the distance Lw between the wire tip and the workpiece to be welded has reached the value of the backward distance setting signal Ls by the backward feeding described in the description section of the first embodiment from the initial arc occurrence time point. Arc start control according to the first embodiment, which is determined when a reverse feed time Tr, which will be described later, reaches a value of a reverse feed time setting signal Trs determined in accordance with the reverse distance setting signal Ls and the reverse feed speed setting value Wr. Is the method. The invention of Example 3 will be described below.
[0036]
FIG. 8 is a block diagram of a welding power source apparatus for carrying out the arc start control method according to the third embodiment. In this figure, the same circuit blocks as those in FIG. 5 described above are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, the reverse feed time setting circuit TRS and the reverse feed timer circuit TR, which are circuit blocks different from those in FIG. 5 surrounded by a dotted line, will be described with reference to FIG.
[0037]
The reverse feed time setting circuit TRS outputs a reverse feed time setting signal Trs determined corresponding to the reverse distance setting signal Ls and the reverse feed speed setting value Wr. This correspondence is Trs [s] = Ls [mm] / Wr [mm / s].
The reverse feed timer circuit TR is a circuit that replaces the distance discriminating circuit LD described above with reference to FIG. 5. The reverse feed timer circuit TR has a reverse feed time Tr from when the short-circuit / arc discrimination signal Sa changes from the short-circuit signal to the arc generation signal. The distance coincidence signal Ld is output when the value of the reverse feed time setting signal Trs is reached. Therefore, the output time point of the distance coincidence signal Ld is a time point when the distance Lwt between the wire tip and the workpiece to be welded at the time of re-forward feeding becomes equal to the value of the backward distance setting signal Ls.
Further, the timing chart of each signal in the welding power source device PS of the third embodiment described above is the same as that of FIG.
[0038]
[Example 4]
The invention of Example 4 described below is It is a reference example of the present invention . In the invention of the fourth embodiment, the fact that the distance Lw between the wire tip and the workpiece to be welded has reached the value of the backward distance setting signal Ls by the backward feeding described above in the description of the first embodiment is as follows. This is the arc start control method according to the first embodiment in which it is determined that the welding voltage value Vw has reached a later-described backward distance voltage setting value Vrs that is determined in accordance with the backward distance setting signal Ls and the initial current setting value Is. The invention of Example 4 will be described below.
[0039]
FIG. 9 is a block diagram of a welding power source apparatus for carrying out the arc start control method of the fourth embodiment. In this figure, the same circuit blocks as those in FIG. 5 described above are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, the receding distance voltage setting circuit VRS and the voltage comparison circuit CM, which are circuit blocks different from those in FIG. 5 surrounded by a dotted line, will be described with reference to FIG.
[0040]
The reverse distance voltage setting circuit VRS outputs a reverse distance voltage setting signal Vrs determined in accordance with the reverse distance setting signal Ls and the initial current setting value Is. Here, if the current value for energizing the arc is constant, the arc length and the welding voltage value Vw are in a proportional relationship. Accordingly, the welding voltage value Vw when the arc length of the initial arc through which the initial current Is is energized (the distance Lw between the wire tip and the workpiece) is equal to the value of the predetermined backward distance setting signal Ls is set as the backward distance voltage setting. Set as the value of signal Vrs.
The voltage comparison circuit CM is a circuit that replaces the distance determination circuit LD described above with reference to FIG. 5, and the welding voltage value Vw when the short-circuit / arc determination signal Sa is an arc generation signal is the reverse distance voltage setting signal Vrs. When this value is reached, the distance coincidence signal Ld is output. Therefore, the output time point of the distance coincidence signal Ld is a time point when the distance Lwt between the wire tip and the workpiece to be welded at the time of re-forward feeding becomes equal to the value of the backward distance setting signal Ls.
Moreover, since the timing chart of each signal in the welding power source device PS of the above-described fourth embodiment is the same as that of FIG. 6 described above, the description thereof is omitted.
When the power supply characteristic during energization of the initial current Is is a drooping characteristic, the fact that the distance Lw between the wire tip and the workpiece to be welded has reached the value of the backward distance setting signal Ls due to the backward feeding described above, It can also be determined that the welding current value Iw in the state has reached the retreat distance current set value determined in accordance with the retreat distance setting signal Ls.
[0041]
【Effect of the invention】
In the present invention, even if the backward feed speed Wfr changes according to the type of shield gas, the diameter of the welding wire, the thickness of the workpiece, the distance Lwt between the wire tip and the workpiece during re-forward feeding. Is controlled to be equal to the predetermined reverse distance set value Ls, so that the transition from the initial arc generation state to the steady arc generation state is always constant even if the reverse feed speed Wfr changes. Smooth in time, so that the bead appearance at the arc start is always good.
Furthermore, in the present invention, the distance Lwt between the wire tip and the workpiece to be welded at the time of re-advance feeding is controlled so as to be equal to the receding distance setting value Ls substantially equal to the steady arc length Lwc. Even if the steady arc length Lwc set to an appropriate value by the voltage setting signal Vs changes according to the steady feeding speed Wfs, the plate thickness of the work piece, etc., the steady arc occurrence state changes from the initial arc occurrence state. The bead appearance at the arc start part is always good with a smooth transition to and from.
[Brief description of the drawings]
FIG. 1 is a block diagram of a welding power source device illustrating an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a welding wire feeding system.
FIG. 3 is a block diagram of a conventional apparatus.
FIG. 4 is a timing chart of each signal of a conventional device.
FIG. 5 is a block diagram of a welding power source apparatus according to the first embodiment.
FIG. 6 is a timing chart of the first embodiment.
FIG. 7 is a block diagram of a welding power source apparatus according to a second embodiment.
FIG. 8 is a block diagram of a welding power source apparatus according to a third embodiment.
FIG. 9 is a block diagram of a welding power source apparatus according to a fourth embodiment.
[Explanation of symbols]
1 Welding wire
2 Workpiece
3a Initial arc (occurrence state)
3b Steady arc (occurrence state)
4 Welding torch
4a Contact chip
5a Feeding roll of wire feeding device
CM voltage comparison circuit
DT delay circuit
Dt delay signal
FC feed control circuit
Fc feed control signal
FCR reverse distance feed control circuit
INV output control circuit
Is Initial current (value / setting value)
IW feed speed integration circuit
Ld Distance coincidence signal
LD distance discrimination circuit
Lr Welding wire receding distance
LS reverse distance setting circuit
Ls Backward distance setting value (signal)
Lw Distance between wire tip and workpiece
Lwc Steady arc length (steady wire tip / workpiece distance)
Lwt Distance between wire tip and work piece during re-advance feeding
PS welding power supply
SA short-circuit / arc discrimination circuit
Sa short / arc discrimination signal
St welding start signal
Tc convergence time
Td delay time (setting value)
TR reverse feed timer circuit
Tr reverse feed time
Trs Reverse feed time setting (value / signal)
TRS reverse feed time setting circuit
VD voltage detection circuit
Vd Voltage detection signal
Vrs Reverse voltage setting (value / signal)
VRS reverse distance voltage setting circuit
VS voltage setting circuit
Vs Voltage setting signal
Vw Welding voltage (value)
WD Feeding speed detection circuit
Wd Feeding speed detection signal
Wf Feeding speed
Wfi initial feed speed
Wfr Reverse feed speed
Wfs Steady feed speed
Wi initial feed speed setting value
WM wire feed motor
Wr Reverse feed speed setting value
WS Regular feed speed setting circuit
Ws Steady feed speed setting signal

Claims (4)

When a welding start signal is input, the welding wire is fed forward to the workpiece, and when the welding wire comes into contact with the workpiece, a predetermined initial current that does not melt the welding wire is welded. When the welding wire is energized from a power supply device and the welding wire is retracted from the workpiece, and the welding wire is separated from the workpiece by the backward feeding, an initial arc in which the initial current is energized is generated and the initial While the arc generation state is maintained, the backward feeding is continued, and when the distance between the wire tip and the workpiece reaches a predetermined backward distance setting value, the welding wire is set at a predetermined steady feeding speed. By moving forward again to the workpiece and applying a steady welding current corresponding to the steady feed speed, the initial arc generation state is smoothly shifted to the steady arc generation state.
The distance between the wire tip and the workpiece to be welded has reached the set value for the backward distance by the backward feeding, and the welding wire backward distance obtained by integrating the feeding speed of the backward feeding from the initial arc occurrence time is An arc start control method for consumable electrode gas shielded arc welding, which is determined by reaching a set back distance. When a welding start signal is input, the welding wire is fed forward to the workpiece, and when the welding wire comes into contact with the workpiece, a predetermined initial current that does not melt the welding wire is welded. When the welding wire is energized from a power supply device and the welding wire is retracted from the workpiece, and the welding wire is separated from the workpiece by the backward feeding, an initial arc in which the initial current is energized is generated and the initial While the arc generation state is maintained, the backward feeding is continued, and when the distance between the wire tip and the workpiece reaches a predetermined backward distance setting value, the welding wire is set at a predetermined steady feeding speed. By moving forward again to the workpiece and applying a steady welding current corresponding to the steady feed speed, the initial arc generation state is smoothly shifted to the steady arc generation state.
That the distance between the wire tip and the work piece has reached the set value for the reverse distance by the reverse feed, the time for the reverse feed from the time of the initial arc occurrence is the set value for the reverse distance and the reverse feed. An arc start control method for consumable electrode gas shielded arc welding, which is determined by reaching a set value for the reverse feed time determined in accordance with the feed speed set value. When the wire feed motor that feeds the welding wire forward or backward from the workpiece and the welding wire is in contact with the workpiece, the short-circuit signal is in an arc generation state. Is a short-circuit / arc discrimination circuit that outputs an arc generation signal as a short-circuit / arc discrimination signal, and a distance discrimination signal that outputs a distance coincidence signal when the distance between the wire tip and the work piece is equal to the value of a predetermined retraction distance setting signal When a circuit and a welding start signal are input, the welding wire is fed forward to the workpiece, and when the short circuit / arc discrimination signal becomes a short circuit signal, the welding wire is moved backward from the workpiece. When the distance coincidence signal is output, a reverse distance feed control circuit that feeds the welding wire forward again to the workpiece at a predetermined steady feed rate, and the welding start signal is input. When Constant current characteristic or the drooping characteristic to form thereafter feeding rate of the steady between energizes the initial current of a small current value which does not melt the welding wire a predetermined up to the point of output the distance match signal from And an output control circuit for forming a constant voltage characteristic for energizing a steady welding current corresponding to
When the welding start signal is input, the welding wire is fed forward, and when the short circuit / arc discrimination signal becomes a short circuit signal, the initial current is energized, the welding wire is fed backward, and the backward movement is performed. When the welding wire is separated from the work piece by feeding, an initial arc in which the initial current flows is generated, and the backward feeding is continued while maintaining the initial arc generation state, and the distance coincidence signal is output. At that time, the welding wire is forwardly fed again at a steady feeding speed and the steady welding current is energized to smoothly transition from the initial arc generation state to the steady arc generation state.
Feeding that outputs the distance coincidence signal when the distance of the welding wire, which is obtained by integrating the feeding speed of the backward feeding from the time when the initial arc occurs, reaches the value of the backward distance setting signal A welding power supply for consumable electrode gas shield arc welding, which is a speed integration circuit. When the wire feed motor that feeds the welding wire forward or backward from the workpiece and the welding wire is in contact with the workpiece, the short-circuit signal is in an arc generation state. Is a short-circuit / arc discrimination circuit that outputs an arc generation signal as a short-circuit / arc discrimination signal, and a distance discrimination signal that outputs a distance coincidence signal when the distance between the wire tip and the work piece is equal to the value of a predetermined retraction distance setting signal When a circuit and a welding start signal are input, the welding wire is fed forward to the workpiece, and when the short circuit / arc discrimination signal becomes a short circuit signal, the welding wire is moved backward from the workpiece. When the distance coincidence signal is output, a reverse distance feed control circuit that feeds the welding wire forward again to the workpiece at a predetermined steady feed rate, and the welding start signal is input. When Constant current characteristic or the drooping characteristic to form thereafter feeding rate of the steady between energizes the initial current of a small current value which does not melt the welding wire a predetermined up to the point of output the distance match signal from And an output control circuit for forming a constant voltage characteristic for energizing a steady welding current corresponding to
When the welding start signal is input, the welding wire is fed forward, and when the short circuit / arc discrimination signal becomes a short circuit signal, the initial current is energized, the welding wire is fed backward, and the backward movement is performed. When the welding wire is separated from the work piece by feeding, an initial arc in which the initial current flows is generated, and the backward feeding is continued while maintaining the initial arc generation state, and the distance coincidence signal is output. At that time, the welding wire is forwardly fed again at a steady feeding speed and the steady welding current is energized to smoothly transition from the initial arc generation state to the steady arc generation state.
The distance discriminating circuit is set to the value of the reverse feed time setting signal that is determined in accordance with the reverse distance setting signal and the reverse feed speed setting value from the initial arc occurrence time. A welding power supply device for consumable electrode gas shield arc welding, which is a reverse feed timer circuit that outputs the distance coincidence signal when the distance is reached.

Images