JP6596675B2 - Arc welding control method - Google Patents

Description

  The present invention relates to an arc welding control method for performing welding by generating an arc between a welding wire as a consumable electrode and a base material as a workpiece.

  In arc welding in which an arc is generated between a welding wire and a base material and welding is performed, when the critical current value is exceeded, the form of transfer of droplets generated by melting the welding wire is spray transfer. A welding method that is performed by alternately repeating a peak current higher than the critical current value and a base current lower than the critical current value for maintaining the arc is called a pulse arc welding method, which is lower than the direct current spray transfer welding. The spray transfer can be performed with an average current.

  The arc is maintained during the base current period in which the base current flows. In the pulse arc welding method, the droplet transfer is performed during a base current period in which the arc force is least affected by the arc force. Therefore, it is possible to greatly reduce spatter.

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

  When spatter occurs, it adheres to the base material, and particularly when spatter adheres to the movable part of the product to be operated, the movable range of the product is limited, and the product value is significantly reduced. For this reason, another process for removing spatters is required, which significantly reduces welding productivity.

  FIG. 6 shows an arc portion 501, a welding voltage, and a welding current waveform in the conventional pulsed arc welding control method disclosed in Patent Document 1. In this pulse arc welding control method, constant current pulse control is performed using a shield gas containing carbon dioxide as a main component.

  As shown in FIG. 6, the output of the peak current Ip is started and the peak time Tp is started. The tip 519P of the welding wire 519 starts to melt from the melting start point t501. In the growth period T502 starting from the melting start point t501, the droplet 523 grows from the tip 519P of the welding wire 519, a constriction 523A is generated between the tip 519P of the welding wire 519 and the droplet 523, and the droplet 523 is the tip 519P. Begin to leave. The droplet 523 is detached from the welding wire 519 at the droplet separation point t503, and the separation of the droplet 523 is completed. In the pulse arc welding, the droplet separation point t503 is repeated from the melting start point t501. At the droplet detachment point t503, the arc length, which is the length of the arc 517, increases in a short time, so that the welding voltage increases sharply. Therefore, when the welding voltage V exceeds a predetermined voltage threshold value or by detecting that the amount of change (dV / dt) per unit time of the welding voltage V exceeds a predetermined value, The separation of 523 from the welding wire 519 can be detected.

  When the arc force applied to the droplet 523 is strong after the droplet 523 is detached, that is, when the density of the arc 517 is high, spatter increases due to the reaction force of the arc force. Therefore, after the droplet 523 is detached, the value of the welding current I is reduced from the peak current Ip to a predetermined reduction current Ir lower than the peak current Ip, thereby preventing the occurrence of sputtering. Thereafter, the welding current I is maintained at the reduction current Ir during the decrease time TM, and after the decrease time TM has elapsed, the welding current I is increased to the original peak current Ip to melt the tip portion 519P of the welding wire 519. When the peak time Tp ends, the base current Ib starts to be output, and the base time Tb is started.

  On the other hand, when spray transfer welding is performed by applying a DC welding current higher than the critical current value without using the pulse arc welding method, the voltage is generally controlled during the arc period. Patent Document 2 discloses an arc welding control method in which short-circuit arc welding is performed by repeating a short-circuit period and an arc period, and as a method for controlling voltage fluctuation in voltage control, an inductance value by electronic reactor control is adjusted during the arc period. Is disclosed.

Japanese Patent No. 5036197 International Publication No. 2013/14569

  An arc welding control method of constant voltage control in a spray transfer state uses an arc welding apparatus that outputs a welding current to a welding wire. The welding current is curved to have a minimum value in the peak current when the droplet formed by melting the welding wire separates from the welding wire and the concave shape when starting and promoting the melting of the welding wire. The arc welding apparatus is controlled to repeat a continuously changing melting current. The arc welding apparatus may be controlled so that the peak current and the melting current fall within a predetermined range.

  With this arc welding control method, spatter can be reduced and a bead with a uniform width can be obtained.

FIG. 1 is a schematic configuration diagram of an arc welding apparatus in the first embodiment. FIG. 2 is a diagram showing an arc portion, a welding voltage, and a welding current of the arc welding apparatus in the first embodiment. FIG. 3 is a diagram showing the current fluctuation width and transition period of the welding current of the arc welding apparatus in the first embodiment. FIG. 4 is a schematic configuration diagram of the arc welding apparatus in the second embodiment. FIG. 5A is a diagram showing a relationship between a welding current and a welding voltage of the arc welding apparatus in the third embodiment. FIG. 5B is a diagram showing a welding voltage and a welding current of the arc welding apparatus in the third embodiment. FIG. 6 is a diagram showing an arc portion, a welding voltage, and a welding current in a conventional arc welding control method.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of an arc welding apparatus 101 according to the first embodiment. The arc welding apparatus 101 includes an arc part 102. FIG. 2 schematically shows the operation of the arc part 2. FIG. 2 shows the welding voltage and welding current of the arc welding apparatus 101 together.

  The arc welding apparatus 101 includes a primary rectification unit 2 that rectifies AC power input from an input power supply 1, a switching unit 3 that controls welding output, and an output from the switching unit 3 that is input to convert the power into a power suitable for welding. The transformer 4 is provided.

  The arc welding apparatus 101 includes a secondary rectification unit 5 that rectifies the secondary output of the transformer 4, a reactor 6 that smoothes the output of the secondary rectification unit 5, a drive unit 7 that drives the switching unit 3, and a welding current. It further includes a welding current detection unit 8 that detects I, a welding voltage detection unit 9 that detects a welding voltage V, and a droplet detachment detection unit 10. The droplet detachment detection unit 10 detects the detachment of the droplet 23 from the distal end portion 19P of the welding wire 19 based on the output of the welding voltage detection unit 9.

  The arc welding apparatus 101 further includes a welding condition setting unit 14 and a storage unit 13. The welding condition setting unit 14 has welding conditions such as the setting current Is of the welding current I, the setting voltage Vs of the welding voltage V, the feed amount of the welding wire 19, the type of shield gas, the type of the welding wire 19, and the diameter of the welding wire 19. Etc. are set. The storage unit 13 includes various values such as a plurality of reactor values, peak currents Ip, melting currents Ig of the electronic reactor control respectively corresponding to information set by the welding condition setting unit 14 and a plurality of values of the feeding amount of the welding wire 19. The parameters are stored.

  The arc welding apparatus 101 further includes an arc control unit 12 that outputs a signal for controlling a current and a voltage when the arc 17 is generated based on outputs from the welding voltage detection unit 9 and the storage unit 13. The drive unit 7 controls the switching unit 3 based on the output of the arc control unit 12.

  The welding wire 19 is fed by a wire feeding motor controlled by the wire feeding unit 20. Electric power for welding is supplied to the welding wire 19 via a tip 16 provided on the torch 15, and an arc 17 is generated between the welding wire 19 and the base material 18 to weld the base material 18. .

  Each component constituting the arc welding apparatus 101 shown in FIG. 1 may be configured independently, or a plurality of components may be combined.

  The operation of the arc welding apparatus 101 will be described below. The arc welding apparatus 101 performs welding voltage V and welding based on a set voltage Vs for setting the output of the welding voltage V and a set current Is for setting the output of the welding current I in arc welding with constant voltage control in a spray transition state. The welding output including the current I is controlled. In FIG. 2, at the melting start point t <b> 1, the droplet 23 is detached from the tip portion 19 </ b> P of the welding wire 19 and the droplet 23 at the tip portion 19 </ b> P of the welding wire 19 starts to grow. At the droplet separation point t3, the welding current I reaches the peak current Ip. In the growth period T2 from the melting start point t1 to the droplet separation point t3, the droplet 23 formed by melting the tip 19P of the welding wire 19 grows. The welding voltage V depends on the arc length L17 of the arc 17. As the droplet 23 grows after the welding wire 19 starts to melt, the arc length L17 becomes shorter, and the resistance value between the welding wire 19 and the base material 18 becomes smaller, so the welding voltage V decreases. When the droplet 23 is detached from the tip 19P of the welding wire 19 at the droplet separation point t3 and the melting of the welding wire 19 is started again, the arc length L17 becomes longer again. Therefore, the resistance value between the welding wire 19 and the base material 18 is increased at the droplet separation point t3, and the welding voltage V is sharply increased accordingly. Thus, the waveform of the welding voltage V is a sawtooth wave. With the change of the welding voltage V along the waveform of the sawtooth wave, the welding current I alternately repeats the melting current Ig and the projecting peak current Ip. Specifically, the welding current I becomes the peak current Ip at the droplet separation point t3 when the droplet 23 is detached. The melting current Ig continuously changes so as to have a minimum value IL by curving into a concave shape that starts and accelerates the melting of the welding wire 19. The wire feed amount that is the speed at which the welding wire 19 is fed is determined by the set current. A plurality of values of the wire feed amount derived experimentally in advance corresponding to a plurality of values of the set current are stored in the storage unit 13. Welding control parameters respectively corresponding to a plurality of values of the wire feed amount are also stored in the storage unit 13. In the first embodiment, the wire feed amount value corresponding to the set current value at which the spray transition state is sufficiently achieved is selected. In the arc welding control method according to the present embodiment, welding is performed based on a set voltage for setting the output of the welding voltage V and a set current for setting the output of the welding current I in arc welding with constant voltage control in a spray transition state. The output is controlled, and the peak current Ip having a protrusion when the droplet 23 is detached and the melting current Ig having a curved waveform continuously changing in a concave shape that starts and accelerates the melting of the welding wire 19 are obtained. Repeatedly, welding is performed by controlling the current fluctuation range It, which is the difference between the peak current Ip and the minimum curve IL of the melting current Ig, to be a predetermined value. The current fluctuation width It is set so that the transition period Tt from when the droplet 23 is detached from the welding wire 19 and melting of the welding wire 19 to when the droplet 23 is separated from the welding wire 19 is within a predetermined range. adjust. In other words, the current fluctuation width It is adjusted such that the timing at which the droplet 23 is detached from the welding wire 19 is one separation / one cycle.

  The current fluctuation width It is centered on the set current or the average value of the moving average of the welding current I over a predetermined period, in other words, within a range of ± 25% to ± 45% with respect to the welding current, more preferably ± 25. % To ± 30% or less. Specifically, the peak current Ip is greater than the average value of the welding current I by 25% or more and 45% or less of 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 25% or more and 45% or less. More preferably, specifically, the peak current Ip is larger than the average value of the welding current I by a value not less than 25% and not more than 30% of the average value of the welding current I, and the minimum value IL of the melting current Ig is the welding current. The current fluctuation width It is controlled so that it is smaller than the average value of the welding current I by 25% or more and 30% or less of the average value of I. The predetermined period for calculating the moving average is an integral multiple of the transition period Tt. The transition period Tt adjusted by the current fluctuation width It is 15 msec or more and 35 msec or less, more preferably 15 msec or more and 20 msec or less. Thereby, since the transition period Tt is stabilized, the fluctuation of the arc length L19 is suppressed, and the bead width is made uniform.

  FIG. 3 shows the relationship between the current fluctuation width It and the transition period Tt. The arc during welding is stabilized by adjusting the current fluctuation width It and the transition period Tt within the arc stable region As, which is the above range of the current fluctuation width It and the transition period Tt shown in FIG.

  In FIG. 3, when the current fluctuation width It is larger than ± 45%, deviates from the arc stable region As, and the current fluctuation width It becomes larger, the melting current Ig having a curved waveform continuously curved and changes in a concave shape. Since the minimum value IL becomes low, the amount of heat input to the welding wire 19 in the growth period T2 in which the welding wire 19 is melted to grow the droplet 23 is insufficient. Therefore, the distance between the tip 19P of the welding wire 19 fed toward the base material 18 and the base material 18 is shortened in the growth period T2, and before the droplet 23 is detached from the welding wire 19, the welding wire The tip 19P of 19 and the base material 18 are short-circuited, the arc becomes unstable, and spatter occurs.

  Further, when the current fluctuation width It is smaller than ± 25% and deviates from the arc stable region As and the current fluctuation width It becomes smaller, the minimum value IL of the melting current Ig becomes higher, so that the welding wire 19 in the growth period T2 is increased. The amount of heat input becomes excessive. This increases the arc reaction force in the growth period T2. Therefore, since the molten droplet 23 at the tip 19P of the molten welding wire 19 is pushed back toward the welding wire 19, the arc becomes unstable and is scattered from the tip 19P of the welding wire 19 to be sputtered.

  Next, a detailed operation for controlling the current fluctuation width It using the inductance value will be described with reference to FIG. The inductance value is, for example, an added value of the reactor 6 as a fixed value and a variable electronic reactor value by electronic reactor control. In the first embodiment, the inductance value of reactor 6 is a fixed value, but may be variable.

  In FIG. 3, when the current fluctuation width It exceeds ± 45% and deviates from the arc stable region As, the electronic reactor value is decreased to increase the inductance value related to the welding output, and voltage control tracking is performed. And the current fluctuation width It is adjusted so as to be in the arc stable region As.

  Further, when the current fluctuation width It is smaller than ± 25% and smaller than the arc stable region As, the electronic reactor value is increased, the inductance value is decreased, and the followability of the voltage control is improved. It is adjusted so that It is within the arc stable region As.

  As described above, by adjusting and controlling the current fluctuation width It so as to be within the arc stable region As shown in FIG. 3, the melting time of the welding wire 19 changes. The transition period Tt for releasing the droplet 23 can be set to 15 msec or more and 35 msec or less in the arc stable region As, and a stable arc 17 can be obtained.

  Furthermore, in the present embodiment, the current fluctuation range It is adjusted by changing a setting voltage that sets an average value that is a moving average of the welding voltage V over a predetermined period. As shown in FIG. 3, the welding current I waveform is centered on the set current so that the current fluctuation range It is within the stable arc stable region As of the arc 17 as shown in FIG. The current fluctuation width It is adjusted so as to fall within the predetermined range.

  In addition, in the constant voltage control arc welding in the spray transfer state, 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 13, and outputs an output control signal corresponding to the inductance value to the driving unit 7. Thereby, the inductance value can be finely adjusted, and the current fluctuation width It can be adjusted so that the current fluctuation width It is within the arc stable region As.

  As described above, in the arc welding control method according to the first embodiment, by adjusting the set voltage and the inductance value in the constant voltage control to optimize the current fluctuation range It, in other words, the fluctuation width of the growth of the droplet 23 is reduced. By optimizing and stabilizing the transition period Tt so that the current fluctuation width It is within the arc stable region As, it is possible to suppress the occurrence of spatter and achieve more stable arc welding.

  In the pulse arc welding method shown in FIG. 6, if the arc length is slightly larger than the diameter of the droplet 523, the tip portion 519P of the welding wire 519 and the base material 518 are not short-circuited, so that spatter can be reduced. Is possible. However, during welding, the distance between the tip 519 </ b> P of the welding wire 519 and the base material 518 due to a disturbance such as a variation in the protruding length, which is the length of the welding wire 519 protruding from the tip, or a displacement of the base material 518. May become shorter. When the distance between the tip 519P of the welding wire 519 and the base material 518 becomes short, the short-circuit between the tip 519P of the welding wire 519 and the base material 518 occurs before the droplet 523 separates from the tip 519P of the welding wire 519. When the welding current I when the short circuit occurs is a high peak current Ip, a large amount of spatter is generated during the short circuit. As described above, a large amount of spatter may occur when a disturbance such as a variation in the protruding length or a displacement of the base material 518 occurs. Further, when the welding current I when the welding wire 519 is melted is a low base current Ib, arc blow due to the lack of directivity of the arc 517 is likely to occur. For this reason, the variation of the arc length is large, and the bead width may be uneven.

  In arc welding apparatus 101 in the first embodiment, current fluctuation width It is controlled using constant voltage control as described above, so that fluctuations in arc length L17 are suppressed. As a result, even if disturbance such as fluctuation of the protruding length L19 of the welding wire 19 protruding from the tip 16 or displacement of the base material 18 occurs, fluctuation of the arc length L17 is suppressed, the transition period Tt is stabilized, and the arc Is stable. Therefore, a minute short circuit between the welding wire 19 and the base material 18 is suppressed, spatter is reduced, and a bead having a uniform width is obtained.

  As described above, the arc welding control method of the constant voltage control in the spray transition state in the first embodiment uses the arc welding apparatus that outputs the welding current I to the welding wire 19. In the arc welding control method, the welding current I is accelerated by starting the melting of the welding wire 19 and the peak current Ip when the droplet 23 formed by melting the welding wire 19 is detached from the welding wire 19. The arc welding apparatus 101 is controlled so as to repeat the melting current Ig which is curved and continuously changed so as to have a minimum value IL in a concave shape. Further, the peak current Ip is larger than the average value of the welding current I by 25% or more and 45% or less of the average value of the welding current I, and the minimum value IL of the melting current Ig is 25% of the average value of the welding current I. The arc welding apparatus 101 is controlled so as to be smaller than the average value of the welding current I by 45% or less.

  Based on the set voltage Vs that sets the output of the welding voltage V, the arc welding apparatus 101 may be controlled such that the welding current I repeats the peak current Ip and the melting current Ig.

  The arc welding control method of constant voltage control in the spray transfer state uses an arc welding apparatus 101 that outputs a welding current I to the welding wire 19. In the arc welding control method, the difference between the peak current Ip and the minimum value IL is such that the transition period Tt from the start of melting of the welding wire 19 until the droplet 23 is detached from the welding wire 19 is 15 msec or more and 35 msec or less. The current fluctuation width It may be controlled.

(Embodiment 2)
FIG. 4 is a schematic configuration diagram of the arc welding apparatus 101a according to the second embodiment. In FIG. 4, the same reference numerals are given to the same portions as those of the arc welding apparatus 101 in the first embodiment shown in FIG. The arc welding apparatus 101a in the second embodiment further includes a time measuring unit 11 connected to the droplet separation detecting unit 10 of the arc welding apparatus 101 in the first embodiment.

  The timer unit 11 detects the transition period Tt by the following method. Since the arc length L17 suddenly increases at the droplet separation point t3 at which the droplet 23 has separated from the tip 19P of the welding wire 19, the welding voltage V detected at the droplet separation point t3 increases sharply. When the welding voltage A exceeds a predetermined voltage threshold or when the amount of change (dV / dt) per unit time of the welding voltage V exceeds a predetermined value, the droplet detachment detection unit 10 It is determined that the droplet 23 has detached, and the separation of the droplet 23 from the welding wire 19 is detected. The timer 11 detects the time from when the droplet detachment detecting unit 10 detects the detachment of the droplet until the detachment of the droplet 23 is detected again as the transition period Tt. The storage unit 13 stores the value of the transition period Tt within the arc stable region As (see FIG. 3) obtained in advance by experiments or the like. The current fluctuation width It is adjusted so that the detected transition period Tt becomes the value of the transition period Tt in the arc stable region As stored in the storage unit 13.

  In the arc welding control method according to the second embodiment, the transition period Tt is detected using a predetermined voltage threshold value of the welding voltage V or a change amount (dV / dt) of the welding voltage V per unit time, and the transition is performed. By adjusting the current fluctuation width It so that the period Tt becomes a predetermined value within the arc stable region As determined in advance, the fluctuation of the protruding length L19 of the welding wire 19, the positional deviation of the base material 18, etc. Even when the disturbance occurs, the arc 17 can be stably arc-welded. Further, since the arc 17 is stabilized in this way, the bead width can be made uniform, and a minute short circuit is suppressed, so that sputtering is also reduced.

(Embodiment 3)
FIG. 5A shows external characteristics showing the relationship between welding current I and welding voltage V in the arc welding control method according to the third embodiment. In FIG. 5A, the vertical axis represents the average value of the welding voltage V, and the horizontal axis represents the average value of the welding current I. FIG. 5B shows the welding voltage V and the welding current I. The transition period Tt from the start of melting of the welding wire 19 to the separation of the droplet 23 is repeated after the droplet 23 is detached from the welding wire 19. In the arc welding control method according to the third embodiment, among the repeated transition periods Tt, the current fluctuation width It of the transition period Tt2 next to the transition period Tt1 is obtained beforehand by experiments or the like according to the arc length L17 in the transition period Tt1. The current fluctuation width It is controlled based on the external characteristic curve shown in FIG. 5A so as to fall within the arc stable region As. The current fluctuation width It may be controlled based on a data table showing the relationship of the external characteristics instead of the curve of the external characteristics shown in FIG. 5A.

  The adjustment of the current fluctuation width It uses at least one welding control parameter among the peak current Ip, the melting current Ig, the transition period Tt, and the set voltage. Then, the current fluctuation width It is adjusted so as to satisfy the current fluctuation width It and the transition period Tt in the arc stable region As shown in FIG.

  The welding voltage detector 9 shown in FIG. 1 detects the arc length L17 using the welding voltage V detected during a predetermined part of the immediately preceding transition period Tt1 or the current transition period Tt2. 5A and 5B, the set current Is and the set voltage Vs are set. Arc welding is performed using welding control parameters corresponding to the set current Is and set voltage Vs. In this arc welding, the average value of the welding voltage V within the transition period Tt1 from the start of melting of the welding wire 19 to the separation of the droplet 23 from the welding wire 19 after the droplet 23 is detached from the welding wire 19 The arc length L17 as an average value in the transition period Tt1 is detected.

  For example, in FIG. 5B, the average value of the welding voltage V (output of the set voltage Vs) is detected as the average value of the arc length L17 in the transition period Tt1 immediately before the transition period Tt2. When the average value of the welding voltage V (the output of the set voltage Vs) is the value V1, the average value of the welding current I (the output of the set current Is) corresponding to the value V1 of the welding voltage V from the external characteristics shown in FIG. 5A. Is the value I1. Therefore, the welding control parameter of the setting voltage Vs of the welding voltage V value V1 and the setting current Is of the welding current I value I1 is used as the welding control parameter of the transition period Tt2.

  Further, the average value of the welding voltage V (the output value of the voltage with respect to the set voltage Vs) in the transition period Tt1 is detected as the average value of the arc length L17, and the welding current is detected in the next transition period Tt2 in accordance with the external characteristics shown in FIG. 5A. The current fluctuation range It is controlled using the welding current control parameter of the peak current Ip and / or the melting current Ig so that the average value of I becomes a value corresponding to the average value of the welding voltage V detected in the transition period Tt1. Thus, the generation of spatter can be suppressed and the bead width can be made uniform.

  For example, the average value of the arc length is detected from the average value of the welding voltage V in the transition period Tt1. In the transition period Tt2 next to the transition period Tt1, the average value of the welding current I (output of the set current Is) determined by the external characteristics shown in FIG. 5A corresponding to the average value of the welding voltage V detected in the transition period Tt1. The current fluctuation width It in the next transition period Tt2 may be controlled using the peak current Ip (Ip2) and / or the melting current Ig (Ig2). Thereby, fine adjustment of the current fluctuation width It becomes possible.

  Similarly, the average value of the arc length is detected from the average value of the welding voltage V in the transition period Tt2. In the transition period Tt3 next to the transition period Tt2, the average value of the welding current I (output of the set current Is) determined by the external characteristics shown in FIG. 5A corresponding to the average value of the welding voltage V detected in the transition period Tt2. The current fluctuation width It in the next transition period Tt3 may be controlled using the peak current Ip (Ip3) and / or the melting current Ig (Ig3). Thereby, fine adjustment of the current fluctuation width It becomes possible.

  Further, when the welding wire 19 is heated red, the arc length L17 is increased, and when the average value of the welding voltage V for each transition period Ttd is relatively high, the amount of heat input to the base material 18 is increased and the base material 18 is increased. May burn out. In this case, the slope of the external characteristic curve of the welding current I and the welding voltage V is relaxed, and a welding control parameter (welding current) with respect to fluctuations in the arc length L17 (the average value of the welding voltage V in each transition period Tt). By improving the followability of (average value of I), the amount of heat input to the base material 18 can be reduced.

  In the arc welding control method in the third embodiment, the arc length L17 (average value of the welding voltage V) in the immediately preceding transition period Tt (Tt1) is detected during welding, and the arc is detected in the next transition period Tt (Tt2). Since the optimum current fluctuation width It is adjusted with respect to the length L17 (average value of the welding voltage V), the arc 17 is stabilized regardless of the protruding length L19 and the positions of the welding wire 19 and the base material 18. The current fluctuation width It is adjusted to the next transition period Tt2 based on the arc length L17 in the transition period Tt1, but if the stability of the arc 17 is not adversely affected, for example, the following period after the transition period Tt2 The current fluctuation width It may be adjusted in the transition period Tt3 based on the arc length L17 in the transition period Tt1.

  Furthermore, even if a disturbance such as a change in the protruding length L19 or a displacement of the base material 18 occurs during welding, the arc 17 is stabilized because the arc length L17 is controlled to be constant. Thereby, a minute short-circuit between the welding wire 19 and the base material 18 is suppressed, it is possible to reduce spatter and make the bead width uniform, and it is also possible to suppress the welding wire 19 from being burned out.

  As described above, in the arc welding control method for performing arc welding for constant voltage control in the spray transition state in the first, second, and third embodiments, the output of the welding voltage V is obtained in arc welding for constant voltage control in the spray transition state. Based on the set voltage Vs to be set and the set current Is to set the output of the welding current I, the welding output (welding voltage V, welding current I) is controlled. The welding current repeats a peak current Ip having a protrusion from which the droplet 23 is detached and a melting current Ig having a curved waveform continuously changing in a concave shape that starts and accelerates the melting of the welding wire 19. The set voltage Vs, the set current Is, the inductance value related to the welding output, and the welding so that the current fluctuation width It, which is the difference between the current Ip and the minimum value IL of the melting current Ig, becomes a predetermined value. The welding current I is controlled using at least one of the external characteristics indicating the relationship between the current I and the welding voltage V. As a result, the welding current I is adjusted by the current fluctuation width It of the welding current I, so that the followability is high with respect to the fluctuation of the arc length L17, and the shield gas is used as in the conventional pulse arc welding method as constant current pulse control. Even if a disturbance such as a variation in the protruding length L19 or a displacement of the base material 18 occurs, the concentration of carbon dioxide gas exceeds 30%, or carbonic acid is not limited. The arc 17 is stabilized even when a shielding gas containing gas as a main component is used. Therefore, a minute short circuit between the welding wire 19 and the base material 18 is suppressed, spatter is reduced, and the bead width is made uniform.

  As described above, the arc welding control method of constant voltage control in the spray transfer state generates arc 17 from the welding wire 19 by outputting the welding output including the welding current I and the welding voltage V to the welding wire 19. The apparatus 101 is used. In the arc welding control method, the inductance value related to the welding output, the welding current I, and the welding voltage V are set such that the current fluctuation width It which is the difference between the peak current Ip and the minimum value IL becomes a predetermined value. The arc welding apparatus is controlled using at least one of the external characteristics indicating the relationship.

  The current fluctuation width It may be adjusted so that the transition period Tt from when the welding wire 19 starts to melt until the droplet 23 separates from the welding wire 19 falls within a predetermined range.

  The transition period Tt may be 15 msec or more and 35 msec or less.

  Using the predetermined voltage threshold value of the welding voltage V or the amount of change (dV / dt) per unit time of the welding voltage V, the droplet 23 is removed from the welding wire 19 after the welding wire 19 starts to melt. The transition period Tt until the separation is detected. The current fluctuation width It is adjusted so that the detected transition period Tt becomes a predetermined value within the arc stable region As determined in advance.

  The peak current Ip is 25% or more of the average value of the welding current I and larger than the average value of the welding current by a value of 45% or less, and the minimum value IL of the melting current Ig is 45% or more of 25% or more of the average value of the welding current I. The following value may be smaller than the average value of the welding current I.

  The peak current Ip is larger than the average value of the welding current I by a value that is 30% or less of the average value of the welding current I, and the minimum value IL of the melting current Ig is the value of the welding current I that is 30% or less of the average value of the welding current. It may be smaller than the average value.

  The arc welding apparatus may include a reactor and perform electronic reactor control. In this case, the inductance value is an addition value of the reactor and the electronic reactor value by the electronic reactor control.

  The arc welding apparatus 101 (101a) repeats the transition period Tt from the start of melting of the welding wire 19 until the droplet 23 is detached from the welding wire 19. According to the arc length L17 of the arc 17 in a certain transition period Tt1 among the repeated transition periods Tt, the average of the welding current I in the transition period Tt2 next to the certain transition period Tt1 in the repeated transition periods Tt. The current fluctuation width It is adjusted using external characteristics so that the value corresponds to the average value of the welding voltage V.

  The current fluctuation width It may be controlled by at least one of the peak current Ip and the melting current Ig.

6 Reactor 17 Arc 18 Base material 19 Welding wire 101 Welding device Ip Peak current Ig Melting current Tt Transition period It Current fluctuation width t1 Melting start point T2 Growth period t3 Droplet separation point TM Decrease time

Claims (15)

An arc welding control method for constant voltage control in a spray transition state using an arc welding apparatus that outputs a welding current to a welding wire,
The welding current has a minimum value in a peak current when a droplet formed by melting the welding wire is detached from the welding wire and a concave shape when starting and promoting melting of the welding wire. Controlling the arc welding apparatus to repeat a melting current that curves continuously and changes continuously,
The peak current is greater than the average value of the welding current by 25% or more and 45% or less of the average value of the welding current, and the minimum value of the melting current is 25% or more of the average value of the welding current. And controlling the arc welding apparatus to be smaller than the average value of the welding current by a value of 45% or less;
An arc welding control method including: The step of controlling the arc welding apparatus so that the welding current repeats the peak current and the melting current is based on a set voltage that sets an output of a welding voltage. The arc welding control method according to claim 1, comprising the step of controlling the arc welding apparatus so as to repeat a current. An arc welding control method for constant voltage control in a spray transition state using an arc welding apparatus that outputs a welding current to a welding wire,
The welding current has a peak current when a droplet formed by melting the welding wire is detached from the welding wire, and a minimum value by curving into a concave shape when starting and promoting melting of the welding wire Controlling the arc welding apparatus to repeat a melting current that continuously changes to have:
A current fluctuation range which is a difference between the peak current and the minimum value is controlled so that a transition period from the start of melting of the welding wire to the time when the droplet is detached from the welding wire is 15 msec or more and 35 msec or less. And steps to
An arc welding control method including: An arc welding control method for constant voltage control in a spray transition state using an arc welding apparatus for generating a welding output including a welding current and a welding voltage on a welding wire to generate an arc from the welding wire,
The welding current has a peak current when the droplet formed by melting the welding wire is detached from the welding wire and a minimum value by curving into a concave shape when starting and promoting melting of the welding wire. Controlling the arc welding apparatus to repeat a continuously changing melting current to have
An inductance value related to the welding output and an external characteristic indicating a relationship between the welding current and the welding voltage so that a current fluctuation range which is a difference between the peak current and the minimum value becomes a predetermined value. Controlling the arc welding apparatus using at least one;
An arc welding control method including: The peak current is larger than the average value of the welding current by a value of 25% or more and 45% or less of the average value of the welding current,
The arc welding control method according to claim 4, wherein the minimum value of the melting current is smaller than the average value of the welding current by a value of 25% or more and 45% or less of the average value of the welding current. The peak current is larger than the average value of the welding current by a value of 30% or less of the average value of the welding current,
The arc welding control method according to claim 5, wherein the minimum value of the melting current is smaller than the average value of the welding current by a value of 30% or less of the average value of the welding current. The arc welding apparatus includes a reactor and performs electronic reactor control,
The arc welding control method according to claim 4, wherein the inductance value is an added value of the reactor and an electronic reactor value by the electronic reactor control. The arc welding apparatus repeats a transition period from the start of the melting of the welding wire until the droplets are detached from the welding wire,
The step of controlling the arc welding apparatus using the at least one of the inductance value and the external characteristic is based on the arc length of the arc at a certain transition period among the repeated transition periods. The current fluctuation width is set using the external characteristics so that the average value of the welding current becomes a value corresponding to the average value of the welding voltage in the transition period next to the certain transition period among the repeated transition periods. The arc welding control method according to claim 4, comprising a step of adjusting. The arc welding control method according to claim 8, wherein the step of adjusting the current fluctuation range includes a step of controlling the current fluctuation range by at least one of the peak current and the melting current. The arc welding control method according to claim 4, further comprising the step of controlling the current fluctuation range by at least one of the peak current and the melting current. An arc welding control method for constant voltage control in a spray transition state using an arc welding apparatus for generating a welding output including a welding current and a welding voltage on a welding wire to generate an arc from the welding wire,
The welding current has a peak current when the droplet formed by melting the welding wire is detached from the welding wire and a minimum value by curving into a concave shape when starting and promoting melting of the welding wire. Controlling the arc welding apparatus to repeat a continuously changing melting current to have
A current fluctuation width that is a difference between the peak current and the minimum value is set so that a transition period from the start of the melting of the welding wire to the time when the droplet is detached from the welding wire is within a predetermined range. Adjusting steps,
An arc welding control method including: The arc welding control method according to claim 11, wherein the transition period is 15 msec or more and 35 msec or less. The step of adjusting the current fluctuation range includes at least an inductance value related to the welding output and an external characteristic indicating a relationship between the welding current and the welding voltage so that the current fluctuation width becomes a predetermined value. The arc welding control method according to claim 11, comprising the step of controlling the arc welding apparatus using one. An arc welding control method for constant voltage control in a spray transition state using an arc welding apparatus for generating a welding output including a welding current and a welding voltage on a welding wire to generate an arc from the welding wire,
The welding current has a peak current when the droplet formed by melting the welding wire is detached from the welding wire and a minimum value by curving into a concave shape when starting and promoting melting of the welding wire. Controlling the arc welding apparatus to repeat a continuously changing melting current to have
Using the predetermined voltage threshold value of the welding voltage or the amount of change per unit time of the welding voltage until the droplet is detached from the welding wire after the melting of the welding wire is started. Detecting a transition period;
Adjusting the current fluctuation range, which is the difference between the peak current and the minimum value, so that the detected transition period is a predetermined value within the stable region of the arc determined in advance;
An arc welding control method including: The step of adjusting the current fluctuation range includes at least an inductance value related to the welding output and an external characteristic indicating a relationship between the welding current and the welding voltage so that the current fluctuation width becomes a predetermined value. The arc welding control method according to claim 14, comprising the step of controlling the arc welding apparatus using one.

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