JP4501355B2 - Arc welding control method and arc welding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc welding control method and an arc welding machine for generating welding arc and controlling welding output.
[0002]
[Prior art]
Arc welding, for example, consumable electrode type arc welding, is a joining method that uses a quantity of heat generated by supplying a voltage to the welding wire tip to generate an arc discharge between the wire tip and the base material.
[0003]
At the time of short circuit transition of consumable electrode arc welding, the arc state and the short circuit state are repeated alternately. However, arc breaks may occur irregularly even during stable short-circuit transfer welding due to changes in the energization point in the welding tip, variations in wire quality, variations in feedability, and the like.
[0004]
The arc breakage causes a deterioration in welding stability and causes an increase in spatter, which adversely affects welding quality.
[0005]
The AS determination unit performs the determination operation by comparing the welding output voltage with a preset value to determine whether the arc state or the short-circuit state.
[0006]
In the conventional technology, the AS determination unit determines whether the welding state is an arc state or a short circuit state, performs the welding output voltage control during the arc state, and performs the welding output current control during the short circuit state. . (For example, see Patent Document 1)
As a recent development trend of welding power sources, multi-process power sources are oriented in accordance with the needs for inverter control frequency improvement, low-cost supply of high-speed processors, and model integration.
[0007]
[Patent Document 1]
JP-A-62-214872
[Problems to be solved by the invention]
However, in a multi-process power source, since it is necessary to control welding by control, it is necessary to ensure a large di / dt in design.
[0009]
In order to ensure di / dt, it is conceivable to increase the no-load voltage of the main transformer or reduce the number of DCL turns on the secondary side to reduce the L value. Therefore, there is a limit to the no-load voltage, and the L value of DCL is reduced to cope with it.
[0010]
When consumable electrode arc welding is performed using a welding power source having a small L value, the output current drops sharply when shifting from short circuit to arc as compared to the case where the L value is large, resulting in arc breakage. Cheap.
[0011]
Further, when CO2 gas is used as the shielding gas, the tendency becomes remarkable.
[0012]
This is because the CO2 gas has a larger voltage gradient in the arc than the argon-rich shield gas, and thus the voltage required to maintain the arc state is increased. Further, when the L value of DCL becomes small, the current ripple for each ignition of the inverter becomes large, which also causes arc breakage.
[0013]
Under such circumstances, the conventional arc welding control method described above has a problem that the arc state cannot be maintained due to a steep drop in current at the moment of transition from the short-circuit state to the arc state, and arc breakage occurs. It was.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, the consumable electrode type arc welding control method of the present invention is configured such that the output current is preliminarily set for a first arc control time set in advance from the time when the arc is regenerated from the short circuit state. Control is performed to the set first arc control set current value.
[0015]
Moreover, in order to solve the said problem, the arc welding machine of this invention uses the said welding control method.
[0016]
By these methods, the consumable electrode type arc welding method of the present invention has an effect of preventing the occurrence of arc break even when the L value of DCL becomes small and the welding state changes from a short circuit to an arc.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment)
Embodiments of the present invention will be described below.
[0018]
FIG. 1 shows an embodiment of the present invention.
[0019]
FIG. 2 is a diagram for explaining an embodiment of a welding control method according to the present invention.
[0020]
FIG. 3 is a diagram for explaining an embodiment of a welding control method according to the present invention.
[0021]
In the figure, 1 is a primary rectification unit, 2 is a smoothing capacitor, 3 is a switching element, 4 is a transformer, 5 is a secondary rectification unit, 6 is a DCL, 7 is a drive unit, 8 is a switching unit, 9 is a setting unit, 10 is a voltage detection unit, 11 is a current detection unit, 12 is an AS determination unit, 13 is a comparison unit, 14 is a differentiation unit, 15 is a first arc control timer, 16 is a first short-circuit control timer, and 17 is a first Arc control unit, 18 is a first short circuit control unit, 19 is a short circuit control unit, 20 is an arc control unit, Ts is a short circuit state period, Ta is an arc state period, Ta1 is a first arc control time, and Ia1 is a first arc control. The set current value, E1 is the time when the arc is regenerated from the short circuit state, E2 is the time when the transition from the short circuit to the arc is started, Is1 is the first short circuit control set current value, and Vasl is the first short circuit control determination value.
[0022]
FIG. 2 shows the melt output current waveform, the welding output voltage waveform, and the output value from the AS determination unit at the time of short circuit transition in consumable electrode arc welding. The AS determination unit outputs an L level when the welding state is a short circuit and an H level when the welding state is an arc state.
[0023]
In this figure, it has shifted to the arc from the short circuit at the time E1.
[0024]
In the present invention, the output current is controlled to the preset first arc control set current value Ia1 during the preset first arc control time Ta1, starting from the point E1 when the arc is regenerated from the short circuit state.
[0025]
The first arc control time Ta1 may be a reference value of a table database created in advance that is referred to by the set current value, the wire type, and the wire diameter, or may be a value calculated from the set current and the output current.
[0026]
The first arc control setting current value Ial may be a preset fixed value (for example, 0.6 ms). The first arc control setting current value Ial is a value obtained by multiplying the output current value detected at the time of arc re-ignition by a coefficient (for example, 0.75). Alternatively, a preset fixed value (for example, 350 A) may be used.
[0027]
After the first arc control time ends, the process proceeds to the arc control is control electrostatic pressure.
[0028]
According to the above method, since the constant current characteristic is obtained for a certain period from the time when the short circuit is transferred to the arc, a droop of current does not occur. Therefore, it is difficult for the output current to become zero (= arc break). Further, the arc state becomes possible stable control for shifting to the arc control (voltage control) after stable. According to the above method, it is possible to prevent an arc break that occurs due to a sudden drop in current that occurs at the time of arc transition from a short circuit.
[0029]
Next, the following embodiment will be described with reference to FIGS.
[0030]
FIG. 3 shows the melt output current waveform, the welding output voltage waveform, and the differential value of the output value welding output voltage from the AS determination unit at the time of short-circuit transition in consumable electrode arc welding.
[0031]
The AS determination unit outputs an L level when the welding state is a short circuit and an H level when the welding state is an arc state. In FIG. 3, the transition start point from the short circuit to the arc can be confirmed at time E2. In the present invention, the output of the welding power source is turned off when the differential value of the welding output voltage exceeds a preset first short-circuit control determination value Vasl. The output of the welding power source may be turned on when the differential value becomes smaller than Vasl or when the preset first short-circuit control output stop time Ts1 has elapsed, and the welding state is arc. It may be the point when it becomes a state. The first short circuit control output stop time Ts1 may be set in advance. After the output of the welding power source is turned ON, the output current is controlled to the first short-circuit control setting current value Is1 set in advance.
[0032]
When the welding state becomes an arc, the welding power source output is turned on, and the arc control is started. By the above method, it is possible to prevent the occurrence of spatter that occurs at the moment of transition from short circuit to arc.
[0033]
Another embodiment will be described with reference to FIG.
[0034]
At the time of short circuit transition of consumable electrode welding, the AS determination unit 12 outputs an L level during a short circuit and an H level during an arc. When shifting from the short circuit to the arc, the AS determination unit 12 outputs an H level to the switching unit 8 and the first arc control timer 15. The first arc control timer 15 starts counting upon receiving the H level from the switching unit 8, and sets the H level to the switching unit 8 during the period until the first arc control time Ta1 preset by the setting unit 9. Output. The switching unit 8 selectively outputs the input signal from the first arc control unit 17 to the drive unit 7 during a period of receiving the H level from the first arc control timer 15 and the H level from the AS determination unit 12.
[0035]
The first arc control unit 17 outputs, to the switching unit 8, the result of feedback calculation of the welding output current value detected by the current detection unit 11 and the first arc control set current value Ia1 preset by the setting unit 9. .
[0036]
The first arc control set current value Ia1 holds the welding output current value from the current detection unit 11 at the moment when the setting unit 9 detects that the input from the AS determination unit 12 is at the H level, A value obtained by multiplying by a coefficient (for example, 0.75) may be used.
[0037]
The first arc control set current value Ia1 is the welding output current value, welding output voltage value, set current value, set voltage value, wire feed amount detected by the setting unit 9 immediately before the occurrence of the arc again. Table fixed values referred to from input values of shield gas type, wire material, and wire diameter may be used. The drive unit 7 receives the signal from the switching unit 8 and drives the switching element 3 to control the power output.
[0038]
With this configuration, it is possible to prevent an arc break accompanying a sharp attenuation of the arc current at the moment of transition from the short circuit to the arc.
[0039]
Still another embodiment will be described with reference to FIG.
[0040]
The welding output voltage value detected by the voltage detection unit 10 at the time of short circuit transition of the consumable electrode welding is output to the differentiation unit 14.
[0041]
The differentiating unit 14 outputs a value obtained by differentiating the welding output voltage value to the comparing unit 13. The comparison unit 13 compares the differential value with the first short-circuit control determination value Vasl preset by the setting unit 9 and outputs an H level to the drive unit 7 when the differential value increases. The drive unit 7 receives the H level from the comparison unit 13 and stops driving the switching element 3.
[0042]
Further, while the drive unit 7 receives the H level from the AS determination unit 12, the drive unit 7 may be prohibited from stopping the switching element 3.
[0043]
With this configuration, it is possible to reduce the occurrence of spatter at the moment of transition from short circuit to arc.
[0044]
The comparison unit 13 compares the differential value with the first short-circuit control determination value Vasl preset by the setting unit 9, and outputs the L level to the drive unit 7 when the differential value becomes small.
The drive unit 7 may receive the L level from the comparison unit 13 and start driving the switching element 3 immediately.
[0045]
In addition, the first short-circuit control timer 16 that starts counting upon receiving the H level from the comparison unit 13 and outputs the H level to the drive unit 7 only during the period up to the first short-circuit control time Ts1 preset by the setting unit 9. It is also possible to receive an L level signal from.
[0046]
Further, the first arc control timer 15 receives the H level from the switching unit 8 and starts counting, and during the period until the first arc control time Ta1 preset by the setting unit 9, Output level.
The switching unit 8 selectively outputs the input signal from the first short-circuit control unit 18 to the drive unit 7 during a period from when the H level from the comparison unit 13 is received until the AS determination unit 12 becomes the H level. The first short-circuit control unit 18 outputs the result of feedback calculation of the welding output current value detected by the current detection unit 11 and the first short-circuit control set current value Is1 preset by the setting unit 9 to the switching unit 8. .
[0047]
With the above configuration, after detecting the transition start point from the short circuit to the arc by the comparison unit, the current can be kept constant until the arc is ignited, and the occurrence of sputtering can be prevented.
[0048]
In addition, although embodiment in the above demonstrated at the time of the short circuit transfer of consumable electrode type welding, it is not limited to this.
[0049]
【The invention's effect】
As apparent from the above description, according to the present invention, it is possible to prevent the occurrence of arc breakage when shifting from a short circuit to an arc, and to prevent welding instability due to arc breakage. As a result, the welding quality can be improved and the amount of spatter can be reduced.
[0050]
Furthermore, it is possible to reduce the amount of spatter generated when shifting from a short circuit to an arc.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a welding control method in the present invention. FIG. 2 is a diagram showing a welding control method in the present invention. FIG. 3 is a diagram showing a welding control method in the present invention.
DESCRIPTION OF SYMBOLS 1 Primary rectification part 2 Smoothing capacitor 3 Switching element 4 Transformer 5 Secondary rectification part 6 DCL
7 drive unit 8 switching unit 9 setting unit 10 voltage detection unit 11 current detection unit 12 AS determination unit 13 comparison unit 14 differentiation unit 15 first arc control timer 16 first short-circuit control timer 17 first arc control unit 18 first Short-circuit control unit 19 Short-circuit control unit 20 Arc control unit Ts Short-circuit state period Ta Arc-state period Ta1 First arc control time Ia1 First arc control set current value E1 Time point when arc is regenerated from short-circuit state E2 Transition from short-circuit to arc Is1 first short circuit control set current value Vasl first short circuit control determination value

Claims (13)

During arc from short circuit condition of a first arc control time set in advance the time of the re-generated as time origin, an arc welding control method of controlling the first arc control set current value set the welding output current advance, the Current control is performed during the first arc control time, voltage control is performed after the end of the first arc control time, and the first arc control set current value is welded immediately before the arc is regenerated by the current control. An arc welding control method that is smaller than the output current value and does not cause arc breakage.   2. The arc welding control method according to claim 1, wherein the first arc control set current value is a value calculated by multiplying a welding output current value immediately before arc regeneration by a coefficient smaller than 1. 3. It said first arc control set current value, an arc welding control method according to claim 1, wherein the constant fixed value set in advance. The arc welding control method according to any one of claims 1 to 3, wherein voltage control is performed until a short circuit occurs after the end of the first arc control time.   The arc welding control method according to any one of claims 1 to 4, wherein the first arc control time is a preset fixed value.   The first arc control time and the first arc control set current value are the welding output current value, the welding output voltage value, the wire feed amount, the shield gas type, which are detected immediately before the arc is regenerated, The arc welding control method according to any one of claims 1 to 5, wherein the arc welding control method is a function of at least one of a wire material and a wire diameter.   An arc welder using the arc welding control method according to claim 1. A current detection unit that detects a welding output current, a voltage detection unit that detects a welding output voltage, and an arc short-circuit detection unit (AS detection unit) that determines whether the welding state is a short circuit or an arc. An arc welding machine that controls an output current to a preset first arc control set current value for a preset first arc control time starting from a time when the occurrence of the arc occurs, the first arc control Current control is performed for a period of time, voltage control is performed after the end of the first arc control time, and the first arc control set current value is greater than the welding output current value immediately before the arc is regenerated by the current control. An arc welding machine that is small and does not cause arc breakage.   9. The arc welder according to claim 8, wherein the first arc control set current value is a value calculated by multiplying a welding output current value immediately before arc regeneration by a coefficient smaller than 1. 10. The arc welding apparatus according to claim 8, wherein the first arc control set current value is a fixed value set in advance. The arc welder according to any one of claims 8 to 10, wherein voltage control is performed until a short circuit occurs after the end of the first arc control time.   The arc welding machine according to any one of claims 8 to 11, wherein the first arc control time is a preset fixed value.   The first arc control time and the first arc control set current value are the welding output current value, welding output voltage value, wire feed amount, shield gas type detected immediately before the arc is regenerated. The arc welder according to any one of claims 8 to 12, wherein the arc welder is a function of at least one of wire material and wire diameter.

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