JP6757892B2 - Arc welding control method - Google Patents

Description

The present invention relates to an arc welding control method in which an arc is generated between a welding wire as a consumable electrode and a base metal to be welded to perform welding.

In arc welding in which an arc is generated between the welding wire and the base metal to perform welding, when the critical current value is exceeded, the transfer form of the droplet becomes spray transfer. A welding method in which a peak current higher than the critical current value and a base current lower than the critical current value for maintaining the arc are alternately repeated is called a pulse arc welding method, which is more than DC spray transition welding. A low average current can be used to perform the spray transition.

In the pulse arc welding method, in order to maintain the arc, the transfer of droplets is performed during the base current period, which is the least affected by the arc force. Therefore, it is possible to significantly reduce sputtering.

However, the pulse arc welding method is restricted by the composition of the shield gas. When the ratio of carbon dioxide gas in the shield gas exceeds 30%, the effect of reducing spatter becomes weak. On the other hand, if a large amount of expensive argon gas is used as the main component, the cost of the shield gas increases. Therefore, there is a demand for an arc welding method capable of stable spray transfer welding using a shield gas containing carbon dioxide as a main component.

When spatter occurs, it adheres to the base material, and when spatter enters the moving portion of the operating product, the movable range of the product is limited and the product value is significantly reduced. For this reason, a post-process for removing spatter is required, which significantly reduces welding productivity.

FIG. 4 is a diagram for explaining a pulse arc welding control method using a shield gas containing carbon dioxide as a main component, and shows the process of the arc portion, the welding voltage V, and the welding current I.

As shown in FIG. 4, the output of the peak current Ip is started and the peak time Tp is started. Melting of the tip of the welding wire is started from the melting start time t3, and the droplet grows at the tip of the welding wire during the growth period T4 of the droplet, and a constriction is generated and the droplet begins to separate. At the time of droplet detachment t5, the droplet is detached and the droplet detachment is completed. Pulse arc welding is performed in which the melting start time t3 and the droplet detachment time t5 are repeated. At the time point t5 when the droplets are separated, the arc length becomes long in a short time, so that the welding voltage V sharply increases.

Therefore, when the welding voltage V exceeds a predetermined voltage threshold value, or when the amount of change (dV / dt) of the welding voltage V per unit time exceeds a predetermined value, the droplets are separated. Can be detected.

After the droplets are separated, if the arc force applied to the droplets is strong, that is, the arc density is high, the reaction force of the arc force increases the sputtering. Therefore, after the droplets are separated, the welding current I is reduced from the peak current Ip to a predetermined lowering current Ir lower than the peak current Ip to prevent the occurrence of spatter.

After that, the welding current I is maintained at the lowering current Ir during the lowering period TM, and after the lowering period TM elapses, the welding current I is increased to the original peak current Ip to melt the tip of the wire. When the peak time Tp ends, the base current Ib starts to be output, and the base time Tb starts (see, for example, Patent Document 1).

Japanese Patent No. 5036197

The arc welding apparatus is controlled by an arc welding control method so as to melt a part of the welding wire. By performing an operation of detecting that the droplet of the welding wire has separated from the welding wire, the time when the droplet has separated from the welding wire is detected. Immediately after the droplet breaks off, the welding current is reduced to the reduced current. In the step of reducing the welding current to the reduced current, the welding current is reduced to the reduced current and then increased to the predetermined current after a predetermined current reduction period has elapsed.

By this arc welding control method, spatter can be reduced and beads having a uniform width can be obtained.

FIG. 1 is a schematic configuration diagram of an arc welding apparatus according to an embodiment. FIG. 2 is a diagram showing an arc welding control method according to the embodiment. FIG. 3 is a diagram showing another arc welding control method according to the embodiment. FIG. 4 is a diagram showing a conventional pulse arc welding control method.

FIG. 1 is a schematic configuration diagram of an arc welding apparatus 1001 according to an embodiment. The arc welding device 1001 inputs the primary rectifying unit 2 that rectifies the AC power input from the input power supply 1, the switching unit 3 that controls the welding output, and the output of the switching unit 3 and converts the power into power suitable for welding. The transformer 4 is provided.

The arc welding device 1001 includes a secondary rectifying unit 5 that rectifies the secondary output of the transformer 4, a reactor 6 that smoothes the output of the secondary rectifying unit 5, a driving unit 7 that drives the switching unit 3, and a welding current. Based on the outputs of the welding current detection unit 8 that detects the welding current, the welding voltage detection unit 9 that detects the welding voltage, and the welding current detection unit 8 and the welding voltage detection unit 9, the droplets at the tip of the welding wire 18 are released. A droplet detachment detection unit 10 for detecting is further provided.

The arc welding device 1001 further includes a welding condition setting unit 13 and a storage unit 12. The welding condition setting unit 13 sets welding conditions such as a set current, a set voltage, a wire feed amount, a shield gas type, a wire type, and a wire diameter. The storage unit 12 stores various parameters such as information set by the welding condition setting unit 13 and a reactor value of electronic reactor control for each wire feeding speed.

The arc welding device 1001 further includes an arc control unit 11. The arc control unit 11 controls the current and voltage at the time of arc generation based on the outputs from the welding voltage detection unit 9, the droplet detachment detection unit 10, and the storage unit 12. Output the signal to be welded. The drive unit 7 controls the switching unit 3 based on the output of the arc control unit 11.

The welding wire 18 is fed by a feed motor controlled by a wire feed unit 19. Power for welding is supplied to the welding wire 18 via a tip 15 provided on the torch 14, and an arc 20 is generated between the welding wire 18 and the base metal 17 to perform welding.

It should be noted that each of the constituent parts constituting the arc welding apparatus 1001 shown in FIG. 1 may be individually configured, or a plurality of constituent parts may be combined and configured.

The operation of the arc welding apparatus 1001 will be described below. FIG. 2 shows an arc welding control method in the arc welding apparatus 1001, showing the welding wire 18 of the arc welding apparatus 1001, the welding current I, the welding voltage V, and the welding resistance R which is the ratio of the welding voltage V to the welding current I. Is shown. The detection invalid period T6 is a period during which detection is not performed even if the threshold value for withdrawal detection is exceeded.

During the welding, disturbances such as fluctuation of the protruding length L18, which is the length protruding from the torch 14 of the welding wire 18, and misalignment of the base metal 17 occur. Welding is performed by constant voltage control that is resistant to disturbance based on the set current Is and the set voltage Vs set by the operator.

The storage unit 12 stores the feeding amount, which is the speed at which the welding wire 18 is fed. Feed rate of the welding wire 18 is determined by the setting current Is, are previously experimentally derived for the set current Is. The storage unit 12 stores the feed amount of the welding wire 18. The storage unit 12 also stores a plurality of values of welding control parameters corresponding to the plurality of values of the feed amount of the wire 18.

In the arc welding control method of the embodiment, in the arc welding of constant voltage control in the spray transition state, the set voltage Vs for setting the output of the welding voltage V and the set current Is for setting the output of the welding current I are used. The welding output, which is the welding voltage V and the welding current I, is controlled. In the operation shown in FIG. 2, the welding current I is curved in a concave shape so as to have a minimum value IL by starting and promoting melting of the protruding peak current Ip and the welding wire 18 when the droplet 23 is separated. The melting current Ig, which changes continuously, is repeated alternately. Welding is performed by controlling the welding output so that the current fluctuation width It, which is the difference between the peak current Ip and the minimum value IL of the melting current Ig, becomes a predetermined value. The current fluctuation width It is set so that the transition cycle Tt from when the droplet 23 is separated from the welding wire 18 until the welding wire 18 is melted and then the droplet 23 is separated from the welding wire 18 is within a predetermined range. It will be adjusted. In other words, the current fluctuation width It is adjusted so that the droplet 23 is separated from the welding wire 18 only once per transition cycle Tt.

The current fluctuation width It is a width of ± 25% or more and ± 45% or less of the center value, more preferably the center value, centered on the average value of the moving average of the welding current I for a predetermined period or the center value which is the set current Is. The welding output is controlled so as to be ± 25% or more and ± 30% or less of. Specifically, the peak current Ip is 25% or more and 45% or less of the above-mentioned center value of the welding current I, which is larger than the center value of the welding current I, and the minimum value IL of the melting current Ig is the welding current I. The current fluctuation width It is controlled so that it is smaller than the center value of the welding current I by a value of 25% or more and 45% or less of the center value.

Specifically, the peak current Ip is 25% or more and 30% or less of the average value of the welding current I, which is larger than the average value of the welding current I, and the minimum value IL of the melting current Ig is the average value of the welding current I. The current fluctuation width It is controlled so that it is smaller than the average value of the welding current I by a value of 25% or more and 30% or less. The above-mentioned predetermined period for calculating the moving average is an integral multiple of the transition cycle Tt. The transition period Tt adjusted by the current fluctuation width It is 15 msec or more and 35 msec or less, and more preferably 15 msec or more and 20 msec or less. As a result, since the transition cycle Tt is stabilized, fluctuations in the arc length L20, which is the length of the arc 20, are suppressed, and the width of the bead generated by welding can be made uniform.

In the embodiment, the feed amount of the welding wire 18 that is sufficiently in the spray transition state is selected. The wire feeding amount of the welding wire 18 is determined by the set current Is.

At the start of melting t3, the droplet 23 at the tip 18P of the welding wire 18 begins to melt and begins to grow, and after the growth period T4 at which the droplet 23 grows, the droplet 23 reaches the tip 18P of the welding wire 18 at the time of withdrawal t5. Withdraw from. If the welding current I when the droplet 23 is separated is large, the arc reaction force becomes large. Since the droplet 23 is pushed back in the direction toward the welding wire 18 by the arc reaction force, the droplet 23 does not stably separate and becomes spatter and scatters. Therefore, the welding current I is reduced immediately after detecting the droplet separation time point t5 from which the droplet 23 is separated, and the welding current I is suppressed to suppress the arc reaction force and reduce sputtering.

It is detected that the welding voltage V sharply increases or the welding resistance R sharply increases at the droplet detachment time t5 because the arc length L20 suddenly becomes long at the droplet detachment time t5 when the droplet 23 is detached. It is detected that the droplet 23 is separated from the tip 18P of the welding wire 18. In the droplet detachment detection unit 10, the welding wire 18 has the welding wire 18 changed according to the change amount of the welding resistance R or the welding resistance R per unit time, or the absolute value of the welding voltage V or the change amount of the welding voltage V per unit time. It is detected that the tip 18P is detached from the tip 18P, and the time point t5 of the droplet detachment is detected.

In the arc welding control method of the embodiment, the droplet detachment detection unit 10 detects that the droplet 23 has detached due to the amount of change in the welding resistance R per unit time for the following reasons. The welding voltage V in the spray transition state changes agilely due to fluctuations in the arc length L20. Therefore, when the detachment of the droplet 23 is detected by using the amount of change in the welding voltage V per unit time or the absolute value of the welding voltage V, erroneous detection due to pulsation, which is a minute fluctuation of the welding voltage V, frequently occurs. Since the welding resistance R does not change sharply due to pulsation but changes slowly, it is possible to suppress the occurrence of erroneous detection. Further, since the welding resistance R has little pulsation (steep fluctuation), it is possible to set a small threshold value used for detecting the amount of change in the welding resistance R per unit time due to the detachment of the droplet 23. Therefore, it is possible to detect the detachment of the droplet 23 early and accurately based on the amount of change in the welding resistance R per unit time as compared with the welding voltage V and the amount of change thereof.

After detecting the detachment of the droplet 23, the welding current I is sharply reduced from the peak current Ip before the droplet 23 is detached to the reduced current Ir in order to reduce the arc reaction force and suppress spatter. The current reduction period T1 is maintained at the reduction current Ir. The value of the reduced current Ir may be experimentally set in advance to a value at which the tip 18P of the welding wire 18 after the output of the reduced current Ir melts smoothly regardless of the stable region of the current fluctuation width It. When the reduced current Ir becomes small, the amount of heat input to the welding wire 18 is insufficient, so that the droplet 23 does not start to melt smoothly and the arc 20 becomes unstable. Further, if the reduced current Ir is large, the effect of reducing sputtering is weakened.

The constant current control pulse arc welding method shown in FIG. 4 can reduce spatter because the tip of the welding wire and the base metal do not short-circuit when the arc length is even slightly larger than the diameter of the droplet. Is. However, during welding, the distance between the tip of the welding wire and the base metal may be shortened due to disturbances such as fluctuations in the protruding length of the welding wire protruding from the tip and misalignment of the base metal. The constant current control is easily affected by disturbances such as fluctuations in the protrusion length and misalignment of the base metal. In particular, when the distance between the tip of the welding wire and the base metal is shortened, the tip of the welding wire and the base metal are short-circuited before the droplets are separated. Then, when the current at the time of short circuit is high, a large amount of sputtering occurs. In spray transfer welding in pulse arc welding using carbon dioxide as the shield gas, the arc reaction force is particularly large, and the droplets grown at the tip of the welding wire are pushed back toward the welding wire. Therefore, since the droplets do not separate stably, the frequency of short circuits with the base metal is high, and a large amount of spatter is scattered.

That is, in spray welding using carbon dioxide gas, a large amount of spatter is generated when the droplets are separated and when disturbances such as fluctuations in the protruding length and displacement of the work are generated.

In the arc welding control method of the embodiment, as shown in FIG. 2, the undershoot of the current generated when the reduced current Ir is output converges within the current decrease period T1. After the current decrease period T1 has elapsed, the welding current I is increased to a predetermined current If during the current increase period T2 with a predetermined inclination α.

The current decrease period T1 is shorter than the current increase period T2. When the current decrease period T1 becomes long, the period when the current is low becomes long, and the arc becomes unstable. Further, when the current rise period T2 becomes short and the angle α of the rise of the welding current I becomes large, the current flows through the welding wire 18 at once and becomes reddish, and the force pushing the molten pool becomes too large to generate spatter. It is desirable that the current increase period T2 is a period during which the welding current I is increased to a predetermined current If by suppressing scattering of spatter due to melting and detachment of the droplet 23. "

In order to secure heat input to the tip 18P of the welding wire 18 when the droplet 23 begins to melt, the inclination α and the current rise period T2 are set, and the predetermined current If after the detachment of the droplet 23 is detected is melted. It should be substantially the same as the peak current Ip before the detection of the detachment of the drop 23. As a result, in the period T7 during which the constant voltage control is performed from the time when the welding current I rises to the predetermined current If to the time when the droplet is removed t5, the difference between the predetermined current If and the minimum value IL of the melting current Ig is used. By adjusting and optimizing a certain current fluctuation width It, the transition cycle Tt from the start of melting of the welding wire 18 to the detachment of the droplet 23 is stabilized, so that the arc 20 is stabilized.

Here, constant current control is performed during a predetermined period Tft, which is the sum of the current decrease period T1 and the current increase period T2, and constant voltage control is performed during the period T7. Switching from constant current control to constant voltage control stabilizes the constant current control of Tft for a predetermined period, which is a period for reducing spatter, and the constant voltage control for T7, which is a period for growing droplets 23 and stabilizing the arc. Immediately after the welding current I rises to a predetermined current If, it is carried out.

As described above, in the arc welding control method using the arc welding apparatus 1001 of the embodiment, the peak current Ip and the melt current Ig whose welding current I is curved in a concave shape are alternately repeated. After the welding current I is sharply lowered after the droplet detachment time t5 when the detachment of the droplet 23 is detected, the welding current I is increased to a predetermined current If during the current increase period T2 with a predetermined inclination α. The welding current I is increased during the current rise period T2 with a predetermined slope α so that the predetermined current If is substantially the same as the peak current Ip before the detachment of the droplet 23 is detected, and at least the current fluctuation width It is increased. Control. As a result, generation of spatter and insufficient heat input can be suppressed, and welding can be performed with a stable arc 20.

The predetermined slope α that increases to a predetermined current If during the current increase period T2 is smaller than the slope β when the slope β that sharply lowers the welding current I after the droplet detachment time t5 is defined. ..

FIG. 3 shows another arc welding control method in the arc welding device 1001, and is a welding resistance which is a ratio of the welding wire 18 of the arc welding device 1001, the welding current I, the welding voltage V, and the welding voltage V to the welding current I. Indicates R. In FIG. 3, the same reference numbers are assigned to the same parts as those in FIG. In the present embodiment, the feed amount of the welding wire 18 that is sufficiently in the spray transition state is selected. The welding current I is maintained constant until the droplet detachment time t5 when the droplet 23 is detached after increasing to a predetermined current If. The feed amount of the welding wire 18 is determined by the set current Is. Also in the operation shown in FIG. 3, similarly to FIG. 2, the welding current I is sharply lowered after the droplet detachment time point t5 when the detachment of the droplet 23 is detected, and then a predetermined current is applied during the current increase period T2 with a predetermined inclination α. Increases to If. The welding current I is increased and controlled during the current rise period T2 with a predetermined slope α so that the predetermined current If is substantially the same as the peak current Ip before the detachment of the droplet 23 is detected. As a result, generation of spatter and insufficient heat input can be suppressed, and welding can be performed with a stable arc 20.

The storage unit 12 may store the inductance value of the electronic reactor control as a welding control parameter. The constant voltage control current of spray transition welding using carbon dioxide as the shield gas can be adjusted, for example, by adjusting the inductance value.

Further, the current fluctuation width It is controlled by changing the inductance value related to the welding output. The inductance value is an addition value of the reactor 6 and the electronic reactor value of the electronic reactor control stored in the storage unit 12, and the output control signal based on this inductance value is output to the drive unit 7.

The welding current I having the current fluctuation width It shown in FIG. 2 is easier to control the detachment of the droplet 23 in the spray transition than the constant welding current I shown in FIG. By controlling the current fluctuation width It of the curved waveform, the welding current I is reduced when the droplet 23 grows at the tip 18P of the welding wire 18, and the welding current is increased when the droplet 23 is separated. This is because it is possible to do so.

If the current fluctuation width It is too large, the melting current Ig becomes small, so that the amount of heat input to the welding wire 18 when the droplet 23 grows is insufficient. Therefore, the distance between the tip 18P of the welding wire 18 fed toward the base material 17 and the base material 17 becomes shorter when the droplet 23 grows. Therefore, the tip 18P of the welding wire 18 does not sufficiently grow the droplet 23, the tip 18P of the wire 18 does not sufficiently melt, and the tip 18P of the welding wire 18 and the base metal 17 are separated before the droplet 23 is separated. Short circuit. As a result, the arc 20 becomes unstable and spatter occurs.

Further, if the current fluctuation width It is too small, the minimum value IL of the melting current Ig becomes large, so that the arc reaction force when the droplet 23 grows becomes large. Therefore, the droplet 23 at the tip 18P of the melted wire 18 is pushed back toward the welding wire 18, so that the arc 20 becomes unstable and scatters from the tip 18P of the welding wire 18 to cause sputtering. Therefore, by optimizing the current fluctuation width It, the transition cycle Tt from the start of melting of the welding wire 18 to the release of the droplet 23 is stabilized, so that the arc 20 is stabilized.

As described above, in the spray transition welding using a gas containing carbon dioxide as a main component, the current fluctuation width It is adjusted by constant voltage control to control the welding current I. When the curved welding current I shown in FIG. 2 is used, the droplet 23 grows stably, and the droplet 23 can be separated from the welding wire 18 at a stable cycle. Further, since the droplet 23 grows stably and the droplet 23 is released at a stable cycle, the arc 20 is stabilized and the arc length L20 is controlled to be always constant. Since the arc length L20 is constant, fluctuations in the arc length L20 are suppressed even when disturbances such as fluctuations in the protruding length L18 and misalignment of the base metal 17 occur, so that minute short circuits are suppressed and sputtering occurs. It is reduced and at the same time a bead with a uniform width is obtained.

In spray transfer welding using a shield gas containing carbon dioxide as a main component, the detachment of the droplet 23 is detected, and immediately after the detachment is detected, the welding current I is reduced to the lowering current Ir. After that, after the welding current I reaches a predetermined current If through the current decrease period T1 and the current increase period T2, the melt current Ig curved in a concave shape is output.

By detecting the droplet detachment time point t5 at which the droplet 23 is detached, the welding current I is sharply reduced from the peak current Ip to the decrease current Ir immediately after the droplet detachment time point t5, so that the droplet 23 is detached. The arc reaction force at that time can be suppressed, and the spatter generated when the droplet 23 is separated can also be reduced.

When the welding control is switched from constant current control before and after the predetermined current If to constant voltage control, in other words, the constant current from the detection of the detachment of the droplet 23 until the welding current I reaches the predetermined current If. At the time when the predetermined period Tft in which the control is performed and the period T7 in which the constant voltage control is performed are switched, hunting of the welding current I is likely to occur, and hunting of the value of the welding resistance R is likely to occur accordingly. False detection of withdrawal may occur.

Specifically, after detecting the detachment of the droplet 23, constant current control is performed to reduce the welding current from the peak current Ip before the droplet 23 detaches to the decreasing current Ir. It is maintained for the decrease period T1, and then the welding current I is increased in the current increase period T2 with a predetermined inclination α to reach the predetermined current If, and then the constant current control is switched to the constant voltage control. The pulsation of the current with the current fluctuation width It after T2 becomes large, causing hunting that makes it difficult to stabilize, and erroneous detection of detachment of the droplet 23 may occur.

When the welding current I reaches the predetermined current If, that is, when the predetermined period Tft elapses, the welding control is switched from the constant current control to the constant voltage control, and hunting of the welding current I is likely to occur. In the welding device that generates the curved current fluctuation width It shown in FIG. 2, the inductance value is small, and hunting is more likely to be promoted and hunting of the welding current is more likely to occur as compared with the constant welding current I shown in FIG. Along with this, hunting of the value of the welding resistance R tends to occur.

In the arc welding control method of the embodiment, it is not detected that the droplet 23 has left the droplet 23 during the predetermined detection invalid period T6 from the time when the current increase period T2 at which the welding current I reaches the predetermined current If has elapsed.

As described above, in the arc welding control method of the present embodiment, the detachment of the droplet 23 is the amount of change in the welding resistance R or the welding resistance R per unit time, or the unit time of the welding voltage V or the welding voltage V. It is detected based on the amount of change per hit. A constant current control is performed during the predetermined period Tft from the droplet detachment time point t5 when the detachment of the droplet 23 is detected, and after the predetermined period Tft elapses, the control is switched to the constant voltage control, and when the predetermined period Tft elapses, that is, From the time when the welding current I reaches a predetermined current If, the detection invalid period T6 does not detect the detachment of the droplet 23. As a result, the droplet 23 can be stably detected by the welding resistance R, minute short circuits can be reduced, and sputtering can be reduced.

As a result, it has high followability to fluctuations in the arc length L20, and unlike the conventional pulse arc welding method, the arc 20 is unstable and spatters without being restricted by the composition of the shield gas containing carbon dioxide as the main component. It is possible to obtain a stable arc 20 with low spatter even in spray transfer welding using a gas containing carbon dioxide as a main component, which tends to generate gas.

As described above, the arc welding control method in the spray transition state uses an arc welding device 1001 that outputs a welding current I to the welding wire 18. In this arc welding control method, the arc welding apparatus 1001 is controlled so as to melt a part of the welding wire 18. By performing an operation of detecting that the droplet 23 composed of a melted part of the welding wire 18 has separated from the welding wire 18, the droplet separation time point t5 at which the droplet 23 has separated from the welding wire 18 is detected. Immediately after the droplet separation time t5, the welding current I is reduced to the lowering current Ir. After the welding current I is reduced to the reduced current Ir and the predetermined current reduction period T1 has elapsed, the welding current I is increased to the predetermined current If.

When controlling the arc welding apparatus 1001 so as to melt a part of the welding wire 18, constant current control may be performed from t5 at the time of droplet detachment, and then constant current control may be switched to constant voltage control. In this case, the operation of detecting that the droplet 23 has separated from the welding wire 18 is not performed during the predetermined detection invalid period T6 from the time when the predetermined current reduction period T1 elapses, and the predetermined detection invalid period T6 elapses. After that, the operation of detecting that the droplet 23 has separated from the welding wire 18 is performed.

It may be detected that the droplet 23 is separated from the welding wire 18 due to the change amount of the welding resistance R or the welding resistance R, or the change amount of the welding voltage V or the welding voltage V.

The arc welding apparatus 1001 may be controlled so that the welding current I becomes a constant current until a part of the welding wire 18 is melted and the droplet 23 is separated from the welding wire 18.

The welding current I is continuously curved so as to have a peak current Ip when the droplet 23 separates from the welding wire 18 and a concave minimum value IL when the welding wire 18 starts and accelerates melting. The arc welding apparatus 1001 may be controlled so as to alternately repeat the changing melting current Ig.

In the above case, the welding current I may be increased to a predetermined current If by a predetermined current rise period T2 with a predetermined slope α so that the predetermined current If is substantially the same as the peak current Ip. In this case, the current fluctuation width It, which is the difference between the peak current Ip and the minimum value IL of the melting current Ig, is controlled.

The current fluctuation width It may be controlled by adjusting a predetermined slope α and a predetermined current rise period T2.

The current fluctuation width It may be adjusted around the set current Is by changing the value of the inductance related to the welding output.

The inductance may consist of the sum of the reactor and the electronic reactor value controlled by the electronic reactor.

The arc welding apparatus 1001 may be controlled so that the welding current I repeats the peak current Ip and the melting current Ig based on the set voltage Vs that sets the output of the welding voltage V.

The reduced current Ir may be smaller than the minimum value IL.

The predetermined current decrease period T1 may be shorter than the predetermined current increase period T2.

In the arc welding control according to the embodiment, the arc length L20 is stable even when disturbances such as fluctuation of the protrusion length L18 and misalignment of the base metal 17 occur in the case of performing arc welding in the spray transition state. Therefore, the workability of the operator is improved, the base metal 17 can be welded with a uniform bead width, and spatter generated when the droplet 23 is separated or a minute short circuit can be suppressed can be suppressed.

Since the arc welding control method according to the present invention can stabilize the arc length, it is useful for arc welding in a state where disturbance occurs.

1 Input power supply 2 Primary rectifying unit 3 Switching unit 4 Transformer 5 Secondary rectifying unit 6 Reactor 7 Drive unit 8 Welding current detection unit 9 Welding voltage detection unit 10 Drip detachment detection unit 11 Arc control unit 12 Storage unit 13 Welding condition setting Part 14 Torch 15 Chip 17 Base material 18 Welding wire 19 Wire feeding part 20 Arc 23 Dropping Ip Peak current Ig Melting current It Current fluctuation width Ir Decrease current T1 Current decrease period T2 Current increase period t3 At the start of melting T4 Growth period t5 Time of droplet detachment T6 Detection invalid period T7 Constant voltage control period Tft Predetermined period Ib Base current α Tilt

Claims (12)

This is an arc welding control method in the spray transition state using an arc welding device that outputs a welding current to the welding wire.
A step of controlling the arc welding apparatus to melt a part of the welding wire, and
A step of detecting a droplet detachment time point when the droplet is detached from the welding wire by performing an operation of detecting that the droplet composed of the molten portion of the welding wire is detached from the welding wire.
A step of reducing the welding current to a reduced current immediately after the droplet detachment, and
In the step of reducing the welding current to the reduced current, a step of reducing the welding current to the reduced current and then increasing the welding current to a predetermined current after a predetermined current reduction period has elapsed.
Arc welding control method including. The step of controlling the arc welding apparatus to melt the part of the welding wire is
The step of performing constant current control from the time of droplet detachment and
The step of switching the constant current control to the constant voltage control,
Including
The step of detecting the droplet detachment time point does not perform the operation of detecting that the droplet has detached from the welding wire during the predetermined detection invalid period from the time when the predetermined current reduction period elapses. The arc welding control method according to claim 1, further comprising the step of performing the operation of detecting that the droplet has separated from the welding wire after the predetermined detection invalid period has elapsed. The step of detecting the time of the droplet detachment includes a step of detecting that the droplet has detached from the welding wire due to the welding resistance or the amount of change in the welding resistance, or the welding voltage or the amount of change in the welding voltage. , The arc welding control method according to claim 1 or 2. In the step of controlling the arc welding device so as to melt the part of the welding wire, the welding current is constant until the part of the welding wire is melted and the droplets are separated from the welding wire. The arc welding control method according to claim 1 or 2, which comprises a step of controlling the arc welding apparatus so as to be a current. The step of controlling the arc welding apparatus to melt the part of the welding wire is that the welding current causes the peak current when the droplets are separated from the welding wire and the melting of the welding wire. 1 or 2, wherein the arc welding apparatus is controlled so as to alternately repeat a melting current which is curved so as to have a minimum value in a concave shape when starting and promoting. The arc welding control method described. In the step of increasing the welding current to the predetermined current, the welding current is increased to the predetermined current for a predetermined current increase period with a predetermined inclination so that the predetermined current is substantially the same as the peak current. Including the step of increasing the current
The step of controlling the arc welding apparatus so as to melt the part of the welding wire further includes a step of controlling a current fluctuation width which is a difference between the peak current and the minimum value of the melting current. The arc welding control method according to claim 5. The arc welding control method according to claim 6, wherein the step of controlling the current fluctuation width includes a step of controlling the current fluctuation width by adjusting the predetermined inclination and the predetermined current rise period. The step of controlling the arc welding device so as to melt the part of the welding wire is a step of adjusting the current fluctuation width around a set current by changing the value of the inductance related to the welding output. 7. The arc welding control method according to claim 7. The arc welding control method according to claim 8 , wherein the inductance is an sum of a reactor and an electronic reactor value controlled by an electronic reactor. The arc welding control method according to any one of claims 6 to 9, wherein the predetermined current decrease period is shorter than the predetermined current increase period. The step of controlling the arc welding apparatus to melt the part of the welding wire is such that the welding current repeats the peak current and the melting current based on a set voltage that sets the output of the welding voltage. The arc welding control method according to claim 5, further comprising a step of controlling the arc welding apparatus. The arc welding control method according to any one of claims 5 to 11, wherein the reduced current is smaller than the minimum value.

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