JP3990151B2 - Arc start control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc start control method of consumable electrode arc welding in which a welding wire is fed forward and backward to a base material to start an arc 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 base material. When it is determined that the welding wire has come into contact with the base material, the wire feed motor is reversely rotated to feed the welding wire backward from the base material. At the same time, an initial current having a predetermined small current value is applied, and when the welding wire is separated from the base metal due to the backward feeding described above and an initial arc is generated, the welding wire is fed forward again, and a steady welding current is simultaneously generated. 2. Description of the Related Art Conventionally, an arc start control method of consumable electrode arc welding (generally called a retract arc start method) for energizing and shifting from an initial arc generation state to a steady arc generation state has been known. Hereinafter, this arc start control method of the prior art will be described with reference to the drawings.
[0003]
FIG. 1 is a block diagram of a conventional arc welding apparatus. Hereinafter, a description will be given with reference to FIG.
When a welding start signal St is input from a welding start circuit ST provided outside, the welding power source device PS outputs a welding voltage Vw and a welding current Iw for generating an arc and feeds the welding wire 1. Is fed to the wire feed motor WM. The welding wire 1 is fed through the welding torch 4 by a feeding roll 5 directly connected to the wire feeding motor WM. When the wire feed motor WM rotates in the forward direction, the welding wire 1 is fed forward to the base material 2, and when it rotates in the reverse direction, the welding wire 1 is fed backward in a direction away from the base material 2. The welding voltage Vw output from the welding power source device PS is supplied to the welding wire 1 by a contact tip 4a attached to the tip of the welding torch 4. When the welding wire 1 and the base material 2 are in a contact (short circuit) state or an arc 3 generation state, the welding current Iw is energized. On the other hand, when the welding wire 1 and the base material 2 are separated from each other and the arc 3 is not generated, the welding voltage Vw becomes the maximum no-load voltage and the welding current Iw is not energized. Further, the shortest distance between the tip of the welding wire 1 and the base material 2 is the wire tip / base material distance Lw [mm]. Therefore, the distance Lw between the wire tip and the base material during generation of the arc 3 is substantially equal to the arc length.
[0004]
FIG. 2 is a timing chart of each signal of the above-described welding apparatus, and FIG. 3 is a diagram illustrating a feeding state of the welding wire in the welding torch when the length of the welding torch is as short as 0.3 [m]. is there. FIG. 4A shows the time change of the welding start signal St, FIG. 4B shows the time change of the feed control signal Fc, FIG. 4C shows the time change of the welding voltage Vw, and FIG. (D) shows the time change of the welding current Iw, and FIG. (E) shows the time change of the wire tip / base material distance Lw. 3 (F1) shows the welding wire feeding state immediately before time t2, (F2) just before time t3, (F3) at time t4, and (F4) at each time of time t5. Hereinafter, a description will be given with reference to FIG.
[0005]
(1) Period from time t1 to t2 (forward feed period)
At time t1, when the welding start signal St is input (High level) as shown in FIG. 9A, the feed control signal Fc is sent as a positive initial value as shown in FIG. The feed speed is set to Fsi, and the welding wire is fed forward to the base material at the initial feed speed. 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. Further, the external characteristics of the welding power source apparatus during the period from the time t1 to the time t4 are output-controlled to a constant current characteristic or a drooping characteristic in order to pass an initial current Is described later. However, during this period from time t1 to time t2, since the welding wire and the base metal are in an unloaded state, the welding voltage Vw becomes the no-load voltage Vnl as shown in FIG. As shown in FIG. (D), the welding current Iw is not energized. On the other hand, as shown in FIG. 5E, the wire tip / base material distance Lw gradually decreases with time due to forward feeding.
Further, as shown in FIG. 3 (F1), during this period, the feed roll 5 is rotated forward, and the welding wire 1 is fed forward through the liner 4b inserted into the welding torch 4, and the wire tip gradually increases. Approach the base material. At this time, the forward feeding propulsion force acts on the welding wire 1 from the pressure point P1 of the two feeding rolls 5. On the other hand, in order to stably supply power to the welding wire 1 from the power supply point P2 inside the contact tip 4a, the contact resistance of the power supply point P2 is designed to be large. For this reason, a propulsive force is applied to the welding wire 1 at the pressurizing point P1, and a resistance force is applied at the power supply point P2, and between the pressurizing point P1 and the power supply point P2 (corresponding to the welding torch length) Thus, the welding wire 1 is fed forward in a state where it is bent a number of times to the left and right (hereinafter referred to as the play of the welding wire). Therefore, the play of the welding wire becomes longer in proportion to the length of the welding torch.
[0006]
(2) Period from time t2 to t3 (reverse feed period)
At time t2, the welding wire comes into contact with the base metal by the forward feeding in the item (1), and the welding voltage Vw is equal to or lower than a predetermined reference voltage value Vth [V] as shown in FIG. When the short circuit voltage value is changed, the feed control signal Fc becomes a negative value of the reverse feed speed setting value Fsr as shown in FIG. 5B, and the welding wire is fed backward from the base material at the reverse feed speed. Is done. At the same time, as shown in FIG. 4D, the initial current Is having a small current value determined in advance by the constant current characteristic or the drooping characteristic is energized. The value of the initial current Is is set to a small current value of about several [A] to several tens [A].
On the other hand, at time t2, the wire feed motor is switched from forward rotation (forward feed) to reverse rotation (reverse feed), and this delay time for forward and reverse inversion (hereinafter referred to as motor inversion delay time). During this time, the welding wire is continuously fed forward by inertia. However, since the welding wire is already in contact with the base material, the contact state is maintained. Thereafter, as shown in FIG. 3 (F2), the reverse force of the wire feeding motor causes the welding wire 1 to have a driving force for backward feeding from the pressurizing point P1, but because of the contact resistance of the feeding point P2. In addition, a delay time until the play portion of the welding wire is fed backward and the welding wire is not bent between the pressurizing point P1 and the feeding point P2 and becomes a substantially straight line (hereinafter referred to as a play portion feed delay time). During this period, the wire tip does not move. Therefore, from the point of time when switching to reverse feed at time t2, the motor reverse delay time elapses until time t3 until the play feed delay time elapses, as shown in FIG. Thus, since the wire tip does not move, the wire tip / base material distance Lw remains 0 [mm].
[0007]
(3) Period from time t3 to t4 (reverse feed period)
Immediately after time t3, when the welding wire and the base material are separated by the backward feeding of the item (2), an initial arc 3a in which the initial current Is is energized is generated. When the initial arc 3a is generated, the welding voltage Vw becomes an arc voltage value exceeding the reference voltage value Vth as shown in FIG. During the period from the time t3 when the initial arc is generated to the time t4 when the predetermined delay time Td elapses, the reverse feed is continued, so that the arc length of the initial arc 3a is shown in FIG. (Distance Lw between wire tip and base material) becomes gradually longer. The reason for providing the delay time Td is that if the re-forward feed described in the next item (4) is started immediately after the initial arc 3a is generated, the contact state may be brought into contact again. However, since the motor reversal delay time and the idle feed delay time described above occur at the start of re-forward feeding, there is a case where the delay time Td need not be provided.
[0008]
(4) Period from time t4 to t5 (re-forward feed period)
When the delay time Td elapses at time t4, the feed control signal Fc becomes a positive steady feed speed set value Fs as shown in FIG. 5B, and the welding wire is at a steady feed speed. Re-forwarded. At the same time, the external characteristic of the welding power source is output controlled to a constant voltage characteristic corresponding to a predetermined voltage setting value Vs, so that the welding voltage Vw is equal to this voltage setting value Vs as shown in FIG. While becoming a corresponding voltage value, as shown in FIG.
On the other hand, as shown in FIG. 3 (F3), at time t4, the wire feed motor is switched from reverse rotation (reverse feed) to forward rotation (re-forward feed). During the period until the reversal delay time elapses, the backward feeding of the welding wire 1 is continued due to the inertia, so that the arc length (the distance Lw between the wire tip and the base material) is as shown in FIG. Keeps getting longer. Further, after that, during the period until the time t5 until the play part feeding delay time elapses, the welding wire 1 is fed forward again, but as shown in FIG. 3 (F4), the play part of the welding wire 1 is fed. Until the wire is fed, the wire tip does not move. However, as shown in FIG. 4D, since a steady welding current Ic having a value larger than the initial current Is is energized at this time, as shown in FIG. In addition, the arc length Lw continues to increase and reaches the maximum arc length Lp1 [mm] at time t5. That is, the arc length Lw continues to increase during the re-forward feed delay time Ta1 from time t4 to time t5.
[0009]
(5) Period after time t5 (steady feeding period)
At time t5, when the above-described delay time Ta1 at the time of re-advance feeding has elapsed, the feeding speed of the welding wire becomes a substantially steady feeding speed. Therefore, as shown in FIG. It converges to the steady arc length Lc [mm] and enters a steady arc 3 generation state.
[0010]
[Problems to be solved by the invention]
As described above with reference to FIG. 2, when the welding torch length is as short as about 0.3 [m], the re-forward feed delay time Ta1 is, for example, about 10 [ms] for the motor reversal delay time. The feeding delay time is about 10 [ms], and the total is about 20 [ms]. If the re-forward feed delay time Ta1 is about this level, since the arc length overshoot is small, the difference between the maximum arc length Lp1 and the steady arc length Lc is small. For this reason, the welding quality such as the bead appearance and penetration of the arc start portion is substantially good. However, it is rare to use a welding torch length as short as 0.3 [m] as described above because workability is poor, and it is normal to use a welding torch length of about 1 to 3 [m]. It is. As described above, when a welding torch having a normal length is used, the following problems occur in the related art.
[0011]
FIG. 4 is a timing chart corresponding to FIG. 2 when the welding torch length is 1 [m]. The signals in FIGS. 9A to 9E are the same as those in FIG. 2, and their operations are the same as those in FIG. 2 except for the following description. When the welding torch length increases from 0.3 [m] to 1 [m], the play feed delay time becomes longer. Therefore, as shown in FIG. 2E, the re-forward feed delay time Ta2 is considerably longer than Ta1 in FIG. As described above, when the re-forward feed time delay time Ta2 becomes longer, the arc length becomes longer and the overshoot becomes larger during this period, so the maximum arc length Lp2 [mm] is the steady arc length Lc [mm]. Will be much longer than. Further, when the re-forward feed time delay time Ta2 is increased, the convergence time Tb2 is also increased in proportion to the length of time, so that the period in which the arc length is longer than the steady arc length Lc continues for a long time. As a result, the bead appearance during the overshoot period of the re-forward feed time delay time Ta2 and the convergence time Tb2 may deteriorate, and the penetration may fluctuate, resulting in poor welding quality. If the welding torch length becomes longer than 1 [m], the overshoot becomes larger and the welding quality becomes worse. When the welding torch length is 1 [m], the motor reverse delay time is about 10 [ms], the idle feed delay time is increased to about 50 [ms], and the re-forward feed delay The time Ta2 is about 60 [ms]. Therefore, the delay time at the time of re-forward feeding becomes three times longer than when the welding torch length is 0.3 [m].
[0012]
Therefore, the present invention provides an arc start control method capable of preventing deterioration in welding quality due to the overshoot of the arc length due to the above-described delay time during re-forward feeding even when the welding torch length is long. .
[0013]
[Means for Solving the Problems]
As shown in FIGS.
When the welding start signal St is input to the welding power source device, the feed forward of the welding wire to the base material is started and the output of the welding power source device is started. When the welding wire comes into contact with the base material by the forward feed, The reverse feed from the base material of the welding wire is started and the initial current Is having a small current value is supplied. After the reverse feed, the welding wire is separated from the base material and the initial arc 3a is generated, and then the steady feed speed Fs. In the arc start control method of consumable electrode arc welding in which re-advance feeding of the welding wire is started and a steady welding current Ic is applied to shift from the initial arc generation state 3a to the steady arc generation state.
The welding wire is fed forward at an initial high-speed feed speed Fsh that is faster than the steady-state feed speed Fs during a predetermined initial high-speed feed time Th from the start time of the re-forward feed, and thereafter the steady-state feed speed Fsh. The arc start control method is characterized in that forward feeding is performed at a feeding speed Fs.
[0014]
As shown in FIGS.
An arc start control method characterized in that the initial high-speed feeding time Th and / or the initial high-speed feeding speed Fsh described in the first invention are set to appropriate values according to the length of the welding torch. is there.
[0015]
As shown in FIG.
In the arc start control method, the value of the initial high-speed feed time Th described in the first invention is set in response to the time length Tr from the start of reverse feed to the initial arc occurrence time. is there.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, Examples 1 and 2 will be described with reference to the drawings as examples of embodiments of the present invention.
[Example 1]
In the invention of Example 1, the welding wire is fed forward at an initial high-speed feeding speed that is faster than the steady-state feeding speed during a predetermined initial high-speed feeding time from the start of re-advance feeding of the welding wire. After that, the arc start control method performs forward feeding at a steady feeding speed. The initial high speed feeding time and / or the initial high speed feeding speed are set to appropriate values according to the length of the welding torch. In the invention of Example 1, during the initial high-speed feeding time from the start of retransmission feeding, the play wire feeding delay time is reduced by feeding the welding wire at an initial high-speed feeding speed that is faster than the steady feeding speed. As a result, the delay time at the time of re-forward feeding can be shortened. For this reason, the arc length overshoot can be reduced, and the difference between the maximum arc length and the steady arc length can be reduced, thereby preventing deterioration of the welding quality such as the bead appearance and penetration of the arc start part. can do. Hereinafter, the invention of Example 1 will be described with reference to the drawings.
[0017]
FIG. 5 is a block diagram of a welding power source apparatus PS for carrying out the invention of the first embodiment. Hereinafter, a description will be given with reference to FIG.
The output control circuit INV receives a commercial power supply (three-phase 200 [V], etc.) as input and performs output control such as inverter control and thyristor control according to a drive signal Dv described later, and a welding voltage Vw and welding current Iw suitable for welding. Is output.
[0018]
The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The short circuit determination circuit SD outputs a short circuit determination signal Sd that is at a high level when the voltage detection signal Vd is equal to or lower than the predetermined reference voltage value Vth as described above with reference to FIG. The delay circuit TD outputs a delay time signal Td that becomes High level for a predetermined time from the time when the short circuit determination signal Sd changes from High level (short circuit) to Low level (non-short circuit). The initial feed speed setting circuit FSI outputs a predetermined initial feed speed setting signal Fsi. The logic NOT circuit NOT logically inverts the short circuit determination signal Sd and outputs a switching signal Not. The initial feeding switching circuit SI is connected to the a side until the switching signal Not changes from the High level (non-short circuit) to the Low level (short circuit), and the initial feeding speed setting signal Fsi is fed. The control setting signal Fsc is output. After changing from the High level to the Low level, the control signal is switched to the b side, and a reverse feed switching circuit output signal Sr described later is output as the feed speed control setting signal Fsc. The reverse feed speed setting circuit FSR outputs a predetermined reverse feed speed setting signal Fsr. The reverse feed switching circuit SR is connected to the a side until the delay time signal Td changes from the High level to the Low level, and the reverse feed speed setting signal Fsr is used as the reverse feed switching circuit output signal Sr. After the output is changed from the High level to the Low level, the signal is switched to the b side, and an initial high-speed feed switching circuit output signal Sh described later is output as the reverse feed switching circuit output signal Sr. The initial high speed feed speed setting circuit FSH outputs a predetermined initial high speed feed speed setting signal Fsh. The steady feeding speed setting circuit FS outputs a predetermined steady feeding speed setting signal Fs. The initial high-speed feed time timer circuit TH outputs an initial high-speed feed time signal Th that becomes High level for a predetermined time from the time when the delay time signal Td changes from High level to Low level. The initial high-speed feed switching circuit SH is connected to the a side until the initial high-speed feed time signal Th changes from the High level to the Low level, and the initial high-speed feed speed setting signal Fsh is supplied to the initial high-speed feed switching circuit SH. It outputs as the switching circuit output signal Sh, and after changing from the High level to the Low level, switches to the b side and outputs the above-mentioned steady feeding speed setting signal Fs as the initial high speed feeding switching circuit output signal Sh. When the welding start signal St is at a high level (start), the feed control circuit FC sends a feed control signal Fc for feeding the welding wire at a speed corresponding to the feed speed control setting signal Fsc. Output to the wire feed motor WM.
[0019]
The voltage setting circuit VS outputs a predetermined voltage setting signal Vs. The initial current setting circuit ISI outputs a predetermined initial current setting signal Isi. The voltage error amplification circuit EV amplifies an error between the voltage setting signal Vs and the voltage detection signal Vd and outputs a voltage error amplification signal Ev. By the feedback control by this voltage error amplifier circuit EV, the external characteristic of the welding power source device becomes a constant voltage characteristic for supplying a steady welding current. The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The current error amplification circuit EI amplifies an error between the initial current setting signal Isi and the current detection signal Id and outputs a current error amplification signal Ei. By the feedback control by the current error amplifier circuit EI, the external characteristic of the welding power source device becomes a constant current characteristic or a drooping characteristic for supplying an initial current. The external characteristic switching circuit SP is connected to the a side until the delay time signal Td changes from the High level to the Low level, and outputs the current error amplification signal Ei as the error amplification signal Ea, and from the High level to the Low level. After changing to the level, the voltage is switched to the b side and the voltage error amplified signal Ev is output as the error amplified signal Ea. The drive circuit DV outputs the drive signal Dv according to the error amplification signal Ea when the welding start signal St is at a high level (start), and does not output the drive signal Dv when it is at a low level (stop).
[0020]
FIG. 6 is a timing chart of each signal of the above-described welding power source apparatus when the welding torch length is 1 [m]. (A) shows the time change of the welding start signal St, (B) shows the time change of the feed control signal Fc, (C) shows the time change of the short circuit determination signal Sd, Fig. (D) shows the time change of the delay time signal Td, Fig. (E) shows the time change of the initial high-speed feed time signal Th, and Fig. (F) shows the time change of the welding voltage Vw. Fig. (G) shows the time change of the welding current Iw, Fig. (H) shows the time change of the wire tip / base material distance Lw, and Fig. (I1) to (I5) show the welding wire at each time. Indicates the feeding state. Hereinafter, a description will be given with reference to FIG.
[0021]
(1) Period from time t1 to t2
At time t1, when the welding start signal St is input (High level) as shown in FIG. 9A, the feed control signal Fc is sent as a positive initial value as shown in FIG. The feed speed set value Fsi is obtained, and the welding wire 1 is fed forward to the base material 2 at the initial feed speed as shown in FIG. During this period, since the welding wire 1 and the base material 2 are in an unloaded state as shown in FIG. 11 (I1), the welding voltage Vw is the no-load voltage Vnl as shown in FIG. Thus, as shown in FIG. 5G, the initial current Is is not energized. On the other hand, as shown in FIG. 5H, the wire tip / base material distance Lw gradually decreases with time due to forward feeding.
[0022]
(2) Period from time t2 to t3
At time t2, when the welding wire 1 and the base material 2 come into contact with each other by the forward feeding of the item (1) as shown in FIG. 12 (I2), the welding voltage Vw is as shown in FIG. The short-circuit voltage value is equal to or less than the reference voltage value Vth. In response to this, when the short circuit determination signal Sd changes to a high level (short circuit) as shown in FIG. 10C, the feed control signal Fc has a negative value as shown in FIG. The reverse feed speed set value Fsr is set, and the welding wire is fed backward from the base material at the reverse feed speed. At the same time, the initial current Is is energized as shown in FIG. Also, during this period, the wire tip does not move and the wire tip-base metal distance Lw as shown in FIG. Remains 0 [mm].
[0023]
(3) Period from time t3 to t4
Immediately after time t3, as shown in FIG. 11 (I3), when the welding wire 1 and the base material 2 are separated by the backward feeding of the item (2), an initial arc 3a in which the initial current Is is energized is generated. When the initial arc 3a is generated, the welding voltage Vw becomes an arc voltage value exceeding the reference voltage value Vth as shown in FIG. For this reason, as shown in FIG. 5C, the short circuit determination signal Sd changes to the low level (non-short circuit). However, during this period, the reverse feed continues while maintaining the initial arc generation state 3a. Therefore, as shown in FIG. 5H, the wire tip / base material distance Lw during this period gradually increases with time.
[0024]
(4) Period from time t4 to t5
At time t4, when the delay time signal Td changes from the High level to the Low level as shown in FIG. 4D, during the predetermined initial high-speed feed time Th, as shown in FIG. The feed control signal Fc becomes a positive initial high-speed feed speed setting value Fsh, and the welding wire is fed forward again at the initial high-speed feed speed. At the same time, the external characteristic of the welding power source is output controlled to a constant voltage characteristic corresponding to a predetermined voltage setting signal Vs, so that the welding voltage Vw is equal to this voltage setting signal Vs as shown in FIG. A corresponding voltage value is obtained, and a steady welding current Ic is applied as shown in FIG.
On the other hand, as described above, during this period, the arc length continues to become longer due to the motor reversal delay time and the play feed delay time, as shown in FIG. However, since feeding is performed at an initial high-speed feeding speed that is faster than the steady feeding speed, the idle feeding delay time is shortened, and as a result, the re-forward feeding delay time Ta3 is also shortened. For this reason, the arc length overshoot is also reduced, and the difference between the maximum arc length Lp3 and the steady arc length Lc is also reduced.
[0025]
(5) Period after time t5
When the initial high-speed feed time Th elapses at time t5, the feed control signal Fc changes to a positive steady feed speed set value Fs as shown in FIG. It is fed at the feeding speed. As described above, since the overshoot is small and the difference between the maximum arc length Lp3 and the steady arc length Lc is small, the convergence time Tb3 is also shortened as shown in FIG. It converges to Lc.
[0026]
The initial high-speed feed time Th or the initial high-speed feed speed Fsh or both values are set to appropriate values according to the length of the re-forward feed time delay time Ta3 depending on the welding torch length. Is done.
[0027]
[Example 2]
The invention of Embodiment 2 is an arc start control method in which the initial high-speed feed time value is set in response to the length of time from the start of reverse feed to the initial arc occurrence time. That is, in FIG. 6 described above, the initial high-speed feeding time Th is set in response to the backward feeding delay time Tr from the time t2 (reverse feed start time) to the time t3 (initial arc occurrence time). The backward feeding time delay time Tr is a time length during which the short circuit determination signal Sd shown in FIG. 6C is at a high level (short circuit), and can be easily measured. On the other hand, the re-forward feed time delay time Ta is a time from the start of the re-forward feed to the time when the maximum arc length is reached, and is difficult to measure. Therefore, by using the fact that the reverse feed delay time Tr and the re-forward feed delay time Ta change substantially in proportion to the welding torch length, the refeed feed delay time Tr is easily measured. The forward feed delay time Ta is estimated, and the initial high-speed feed time Th is set. At this time, there is also a method in which the initial high-speed feeding time Th is set in advance by measuring the backward feeding delay time Tr before welding. There is also a method of automatically setting the initial high-speed feeding time Th by automatically measuring the backward feeding delay time Tr. The invention of the second embodiment, which is the latter case, will be described below with reference to the drawings.
[0028]
FIG. 7 is a block diagram of a welding power source apparatus for carrying out the invention 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 circuit block indicated by a dotted line different from FIG. 5 will be described. The short circuit time measurement circuit CS measures the length of time that the short circuit determination signal Sd is at a high level (short circuit), and outputs a short circuit time signal Cs. The initial high-speed feed time timer circuit TH according to the second embodiment has an initial high-speed feed time signal that is at a high level for a predetermined time determined by the short-circuit time signal Cs after the delay time signal Td changes from a high level to a low level. Th is output.
[0029]
[effect]
FIG. 8 is a diagram showing a change in the arc length (the distance Lw between the wire tip and the base material) at the time of the arc start to show the effects of the inventions of the first and second embodiments. The horizontal axis in the figure shows the elapsed time from the start of reverse feed, and the vertical axis shows the arc length Lw. In the figure, the dotted line indicates the case of the prior art, and the solid line indicates the case of the present invention. Further, the welding conditions were a welding torch length of 1 [m], a welding wire aluminum alloy A5183 diameter of 1.2 [mm], a steady feed speed Fs = 6 [m / min] (welding current Iw = 100 [A] equivalent) ), Initial high-speed feed speed Fsh = 9 [m / min].
[0030]
The time point of the elapsed time 0 [s] corresponds to time t2 in FIG. 6, and the time point 60 [ms] at which the arc length Lw is not 0 [mm] corresponds to time t3 in FIG. In the prior art, the arc length Lw greatly overshoots and takes a long time to converge to the steady arc length, resulting in poor weld quality such as bead appearance and penetration at the arc start portion. On the other hand, in the present invention, since the overshoot of the arc length Lw is small and converges in a short time, the welding quality of the arc start portion does not deteriorate.
[0031]
【The invention's effect】
In the arc start control method of the present invention, the welding torch length is increased by feeding at an initial high speed feed speed that is faster than the steady feed speed during the initial high speed feed time from the re-forward feed start time. However, since the delay time at the time of re-forward feeding can be shortened, the overshoot of the arc length can be reduced, and the welding quality of the arc start portion can always be improved.
Furthermore, in the invention of the second embodiment, the initial high-speed feeding time is set in response to the backward feeding delay time that is easy to measure, so that it can be set to an appropriate value corresponding to the welding torch length. As a result, the arc length overshoot can be minimized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a conventional welding apparatus.
FIG. 2 is a timing chart of a conventional welding apparatus.
FIG. 3 is a feeding state diagram of a welding wire in a conventional welding apparatus.
FIG. 4 is a timing chart for explaining a problem to be solved in the prior art.
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 welding power source device according to the first embodiment.
FIG. 7 is a block diagram of a welding power source apparatus according to a second embodiment.
FIG. 8 is an arc length change chart at the time of arc start showing the effect of the present invention.
[Explanation of symbols]
1 Welding wire
2 Base material
3 Arc
3a initial arc
4 Welding torch
4a Contact chip
4b liner
5 Feeding roll of wire feeder
CS short circuit time measurement circuit
Cs Short circuit time signal
DV drive circuit
Dv drive signal
Ea Error amplification signal
EI current error amplifier circuit
Ei Current error amplification signal
EV voltage error amplifier circuit
Ev Voltage error amplification signal
FC feed control circuit
Fc feed control signal
FS steady feed speed setting circuit
Fs Constant feed speed setting (value / signal)
FSH initial high-speed feed speed setting circuit
Fsh Initial high-speed feed speed setting (value / signal)
FSI initial feed speed setting circuit
Fsi Initial feed speed setting (value / signal)
FSR reverse feed speed setting circuit
Fsr Reverse feed speed setting (value / signal)
Ic Steady welding current
ID current detection circuit
Id Current detection signal
Is Initial current
ISI initial current setting circuit
Isi initial current setting signal
Iw welding current
Lc Steady arc length
Lp Maximum arc length
Lw Distance between wire tip and base metal / arc length
NOT logic negation circuit
Not switching signal
P1 Pressurization point
P2 feeding point
PS welding power supply
SD short-circuit detection circuit
Sd Short circuit detection signal
SH initial high-speed feed switching circuit
Sh Initial high-speed feed switching circuit output signal
SI initial feed switching circuit
SP external characteristic switching circuit
SR Reverse feed switching circuit
Sr Reverse feed switching circuit output signal
ST Welding start circuit
St welding start signal
Ta Delay time for re-forward feeding
Tb convergence time
TD delay circuit
Td delay time (signal)
TH initial high-speed feed time timer circuit
Th Initial high-speed feed time (signal)
Tr Delay time during reverse feed
VD voltage detection circuit
Vd Voltage detection signal
Vnl No-load voltage
VS voltage setting circuit
Vs Voltage setting (value / signal)
Vth reference voltage value
Vw welding voltage
WM wire feed motor

Claims (3)

When a welding start signal is input to the welding power source device, the welding wire starts to feed forward to the base material and starts to output the welding power source device. When the welding wire comes into contact with the base material by this forward feeding, welding is started. The reverse feed from the base metal of the wire is started, and an initial current of a small current value is applied. In the arc start control method of consumable electrode arc welding that starts re-forward feeding and energizes a steady welding current to shift from the initial arc generation state to the steady arc generation state,
The welding wire is fed forward at an initial high-speed feed speed that is faster than the steady-state feed speed during a predetermined initial high-speed feed time from the start point of the re-forward feed, and thereafter the steady-feed speed. An arc start control method characterized by feeding forward with the An arc start control method characterized in that the initial high-speed feeding time and / or initial high-speed feeding speed according to claim 1 are set to appropriate values according to the length of the welding torch. An arc start control method characterized in that the initial high-speed feed time value according to claim 1 is set in response to a time length from the start of reverse feed to the initial arc occurrence time.

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