JP2018051624A - Arc-welding control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome such concerns that, in a welding tip which forms an opening along a wire insertion hole on a part of the inside thereof and provides to the opening a spring for pressing a welding wire into a wire inserting hole, consumption of the spring feeding electricity to the welding wire at an electricity feeding point becomes easy to proceed by energization on the spring for pressing the welding wire, and also a tip life shortens by lowering of a pressing force due to exothermic heat.SOLUTION: There is provided a new type welding tip for feeding electricity to a welding wire. The welding tip has such an insulation structure that, in the tip top side of a wire insertion hole for inserting the welding wire for electricity feeding, an insulator for electrically insulating the welding wire is provided to a pressing part for pressing the welding wire at the feeding point of the wire insertion hole. The progress of consumption in the pressing part is slow because of no electricity feeding from the pressing part to the welding wire. Further, lowering of a pressing force in the pressing part is restrained because of hardly generating heat, and thereby a tip life is improved.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an arc welding control method in which an arc is generated between a welding wire which is a consumable electrode and a base material which is a workpiece, and welding output control of short-circuit arc welding is performed.

  In recent years, from the viewpoint of protecting the global environment, in the automobile industry, reduction of vehicle steel plates and the like has been progressing year by year in order to reduce weight for the purpose of improving fuel efficiency. In addition, in order to improve productivity, the production tact of the welding process is being improved. For this reason, improvement in welding quality is expected in arc welding of thin plates performed using a robot. In the case where a gap is generated between the base materials to be welded, by suppressing the base material from being melted down, it is possible to increase the yield of the workpieces and reduce the number of rework steps. Therefore, demands for solving these problems from the market are increasing year by year. In response to these requirements, various types of thin plate welding and gap welding have been proposed. For example, in pulse MAG arc welding, the arc length can be adjusted by switching pulse conditions such as pulse current and base current to two pulse current groups (see, for example, Patent Document 1). As a result, in butt welding and lap welding, even if there is a gap, it is possible to suppress burnout by shortening the arc length.

JP-A-4-333368

  However, in recent years, with the progress of thinning due to weight reduction, pulse arc welding with a large heat input is more likely to generate back waves on the back side of the work to be welded than short-circuit arc welding, and there is a higher risk of burn-off. Distortion is likely to occur. The longer the welding length, the greater the effect of this distortion, and there is a risk of causing any occurrence of the welding wire with respect to the workpiece. Moreover, although the heat input can be reduced by reducing the welding current as a whole, there is a problem that the arc becomes unstable. The present application is intended to prevent melting during thin plate welding and to control the amount of heat input to stabilize the arc length.

In order to solve the above-described problem, an arc welding control method of the present invention uses a welding wire that is a consumable electrode to a workpiece to be welded to a first heat input period including a first heat input amount and a second heat input period. An arc welding control method for performing arc welding that periodically repeats a second heat input period consisting of a heat input amount,
The arc length during arc welding is an arc welding control method that is controlled based on a preset arc length adjustment value.
Moreover, the arc welding control method of the present invention is lower than the first heat input amount and the first heat input period consisting of the first heat input amount with respect to the workpiece using the welding wire which is the consumable electrode in the previous period. An arc welding control method for performing arc welding that periodically repeats a second heat input period composed of a second heat input amount,
The first heat input period and the second heat input period each have a short circuit period and an arc period, and the arc length during arc welding is controlled based on a preset arc length adjustment value. It is a control method.

  Further, in the arc welding control method of the present invention, the arc length adjustment value is composed of a first arc length adjustment value, and the first arc length adjustment value is a peak current in the arc period of the second heat input period. And the average value of the base current or the welding current.

  In the arc welding control method of the present invention, the first arc length adjustment value composed of an average value of the welding current in the arc period of the second heat input period is set to the arc period Ta of the first heat input period. The average value of the welding current in the arc period of the second heat input period is 30 A or more and 150 A or less, preferably 40 A or more and 120 A, so that the welding current is reduced to 20% or more and 40% or less, preferably 30%. The arc welding control method is set to the following range.

  In the arc welding control method of the present invention, the base current of the arc period of the second heat input period as the first arc length adjustment value is 25 A or more.

In the arc welding control method of the present invention, the first heat input period and the second heat input period each have a short circuit period and an arc period,
In the first heat input period or the second heat input period, an inflection point that is a switching point between the current increase slope in the short-circuit period and the second current increase slope is in a range of 200 A to 400 A, and more preferably. Is 300A.

  Further, in the arc welding control method of the present invention, the arc length adjustment value further includes a second arc length adjustment value, a set average welding voltage as the second arc length adjustment value is set, and the set average Constant voltage control is performed so that an average welding voltage corresponding to the welding voltage is output. Further, during arc welding, any one of at least the bending point of the short-circuit period, the peak current, the base current, the duration of the peak current, and the duration of the base current in the arc period in the first heat input period An arc welding control method that changes one or more.

  Further, the arc welding control method of the present invention has the second arc length adjustment value individually for each of the first heat input period and the second heat input period, and the second arc length adjustment. The values are a first set average welding voltage corresponding to the first heat input period and a second set average welding voltage corresponding to the second heat input period, and the first heat input period and the This is an arc welding control method in which constant voltage control is performed so that the arc length becomes constant in each heat input period of the second heat input period.

  According to the present invention, a short heat welding period is used to cycle through a low heat input period, which is a second heat input period for reducing the welding current after the short circuit is opened, and a first heat input period in which the heat input amount is larger than the second heat input period. Repeatedly, the heat input is reduced while maintaining a stable arc, the welding of thin plate welding workpieces can be suppressed, the gap tolerance can be improved, the strain can be reduced, and the welding quality can be improved. I can do it.

The figure of the output waveform by the arc welding control method in Embodiment 1 of this invention, the supply waveform of a welding wire, and the droplet transfer state of the welding wire tip The figure which shows schematic structure of the arc welding apparatus in this invention The figure of the output waveform by the arc welding control method in Embodiment 2, 3 of this invention, the supply waveform of a welding wire, and the droplet transfer state of the welding wire tip

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
(Embodiment 1)
First, an arc welding apparatus that performs the arc welding control method of the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of the arc welding apparatus. The arc welding device 20 performs welding by repeating the arc period Ta in the arc state and the short-circuit period Ts in the short-circuit state between the welding wire 22 that is a consumable electrode and the workpiece 21.

  The arc welding apparatus 20 includes a main transformer 2, a primary side rectification unit 3, a switching unit 4, a DCL (reactor) 5, a secondary side rectification unit 6, a welding current detection unit 7, and a welding voltage detection unit. 8, a short circuit detection unit 9, a short circuit / arc detection unit 10, a short circuit opening detection unit 11, and a wire feed speed control unit 16.

  The output control unit 12 includes a short circuit control unit 13 and an arc control unit 14. The wire feed speed control unit 16 includes a wire feed speed detection unit 17, a calculation unit 18, and a forward / reverse feed switching timing control unit 19. The primary side rectification unit 3 rectifies the input voltage input from the input power source 1 outside the arc welding apparatus 20. The switching unit 4 controls the output of the primary side rectification unit 3 to an output suitable for welding. The main transformer 2 converts the output of the switching unit 4 into an output suitable for welding. The secondary side rectification unit 6 rectifies the output of the main transformer 2. A DCL (reactor) 5 smoothes the output of the secondary side rectification unit 6 to a current suitable for welding.

  The welding current detector 7 detects the welding current. The welding voltage detector 8 detects the welding voltage. Based on the output of the welding voltage detection unit 8, the short circuit / arc detection unit 10 determines whether the welding state is a short circuit state in which the welding wire 22 and the workpiece 21 are short-circuited, or the welding wire 22 and the workpiece. It is determined whether the arc is in an arc state where the arc 23 is generated. The short-circuit opening detection unit 11 detects the number of times that the short-circuit state is opened and the arc state is determined.

  The output control unit 12 controls the welding output by outputting a control signal to the switching unit 4. When the short-circuit control unit 13 determines that the short-circuit / arc detection unit 10 is in the short-circuit state, the short-circuit control unit 13 controls the short-circuit current that is the welding current during the short-circuit period. When it is determined that the short circuit / arc detection unit 10 is in the arc state, the arc control unit 14 controls the arc current that is the welding current during the arc period. The arc control unit 14 performs control to reduce the welding current during the second heat input period when the short-circuit open detection unit 11 detects the number of short-circuit opens set by the welding condition setting unit 15.

  The wire feed speed control unit 16 controls the wire feed unit 25 to control the feed speed of the welding wire 22. The wire feed speed detector 17 detects the wire feed speed. Based on the signal from the wire feed speed detection unit 17, the calculation unit 18 calculates an integrated amount of the feed amount of the welding wire 22 for a predetermined time. The forward / reverse switching timing control unit 19 controls the control signal for delaying the switching timing of the feeding of the welding wire 22 from the normal feeding to the reverse feeding based on the signal from the calculation unit 18 or the reverse feeding to the normal feeding. A control signal for delaying the switching timing to is output.

A welding condition setting unit 15 and a wire feeding unit 25 are connected to the arc welding apparatus 20. The welding condition setting unit 15 is used for setting welding conditions in the arc welding apparatus 20. The wire feeding unit 25 controls the feeding of the welding wire 22 based on a signal from the wire feeding speed control unit 16.
The welding output of the arc welding apparatus 20 is supplied to the welding wire 22 via the welding tip 24. Then, welding is performed by generating an arc 23 between the welding wire 22 and the workpiece 21 by the welding output of the arc welding apparatus 20.

  Next, operation | movement of the arc welding apparatus 20 comprised as mentioned above is demonstrated using FIG.

  FIG. 1 is a diagram showing an output waveform by the consumable electrode type arc welding control method in the present embodiment. In arc welding in which the short-circuit period Ts and the arc period Ta are alternately repeated, the time change of the welding current Aw and the welding voltage Vw, the time change of the feeding speed Wf of the welding wire 22, and the droplet transfer state Ww of the welding wire 22 Schematic diagrams (a to h) are shown.

  First, in FIG. 1, in (a) in the droplet transfer state Ww, after a short circuit occurs between the welding wire 22 and the workpiece 21, the droplet of the welding wire 22 is transferred to a molten pool (not shown) on the workpiece 21. I am migrating. Further, the welding current Aw in (a) is controlled so as to increase the welding current with the passage of time in order to open the short circuit state in the short circuit period Ts.

  As an increase mode, for example, as shown in FIG. 1, first, in the short-circuit period Ts, the first current increase slope Aws1 increases, and then the first current increase slope Aws1 has a gentler slope than the first current increase slope Aws1. The current increase slope Aws2 is 2. The current value at the time of switching from the first current increase slope Aws1 to the second current increase slope Aws2 is referred to as a bending point.

  Further, the feeding of the welding wire is fed at the welding wire feeding speed Wf, and is controlled so as to repeat the forward feeding and the reverse direction. Feeding performed in the direction toward the workpiece 21 is forward feeding, and feeding performed in the direction opposite to the forward feeding is reverse feeding. Alternately, the wire feeding speed is changed at a predetermined cycle Wt and a predetermined amplitude Wa, and the welding wire 22 is periodically fed. Wap is the forward feed amplitude, Wtp is the forward feed cycle, Wan is the reverse feed amplitude, and Wtn is the reverse feed cycle. The welding wire feed speed Wf in (a) is reverse feed in order to open the short circuit state in the short circuit period Ts.

  Next, when the welding voltage Vw in (b) rises, a short circuit open is determined. The droplet transfer state Ww in (b) at this time causes a constriction phenomenon on the distal end side of the welding wire 22 due to the pinch effect to transfer the droplet and release from the short circuit state. The control of the welding current Aw from (c) to (d) increases the welding current to a predetermined peak current value Awa1 during the arc period Ta. Thereby, in the droplet transfer state Ww from (c) to (d), the melting rate of the tip of the welding wire 22 is increased, and the grown droplet that forms and grows the droplet is short-circuited again, so that the welding is performed. Form a bead.

  (B) After determining short-circuit opening at time, in (c) and (d), the control of the welding wire feed speed Wf is forward feeding in order to promote the short-circuit. Usually, welding is performed by repeating only the first heat input period Th including the short-circuit period Ts and the arc period Ta via a plurality of times (a), (b), (c), and (d). .

  However, in the present embodiment, the heat input amount is lower than the first heat input period Th passing through (a), (b), (c), and (d) in FIG. 1 and the first heat input period Th. (E) The amount of heat input to the workpiece 21 is reduced by performing welding by periodically repeating the second heat input period Tc via (f), (g), and (h). For example, as shown in FIG. 1, in the first heat input period Th, after the droplets at the tip of the welding wire 22 are grown through (a), (b), (c), and (d), FIG. When the next short-circuit occurrence between the welding wire 22 and the workpiece 21 is detected by the welding voltage Vw, the droplet transfer state Ww in (e) is similar to the droplet transfer state Ww in (a). Twenty-two droplets are transferred to the molten pool.

  The welding current Aw in (e) is controlled so as to increase the welding current with the passage of time in order to open the short-circuit state, similarly to the form of increase in the welding current Aw in (a). Further, the welding wire feeding speed Wf is controlled by reverse feeding in order to promote the opening of the short circuit.

  Further, the droplet transfer state Ww when the welding voltage Vw in (f) determines that the short circuit is opened is similar to the droplet transfer state Ww in (b), and a constriction phenomenon occurs at the tip of the welding wire 22 due to the pinch effect. The droplet is transferred to the molten pool and released from the short-circuit state. Then, the welding current Aw from (g) to (h) is used for the peak current Awa1 during the arc period Ta of the first heat input period Th until the next short circuit between the welding wire 22 and the workpiece 21 occurs. Control to a lower current.

Thereby, the heat input amount in the second heat input period Tc can be reduced. During the arc period Ta in the second heat input period Tc, the base current Awc2 is output after the peak current Awc1 is output. In the first embodiment, the arc length depends on the current waveform Aw. The arc length during arc welding is controlled based on a preset arc length adjustment value. The arc length adjustment value includes the first arc length adjustment value, and includes welding parameters such as peak current Awc1 and base current Awc2 in the second heat input period Tc in which the second heat input amount is set, or the second input heat input. The average value of the welding current Aw during the arc period Ta during the heat period Tc is referred to as a first arc length adjustment value.
The first arc length adjustment value is obtained experimentally in advance, for example. The first arc length adjustment value may be obtained so as to correspond to the weld joint and the plate thickness.

  By reducing the welding current Aw in the arc period of the second heat input period from the welding current Aw in the arc period Ta of the first heat input period Th by the first arc length adjustment value, The heat input amount during the arc period Ta during the heat period Tc is set to a second heat input amount that is lower than the first heat input amount during the first heat input period Th.

  When the work 21 is thin (for example, a plate thickness of 0.6 mm or more and 1.0 mm or less) and excessive heat input or melting due to a gap becomes a problem, the arc of the second heat input period Tc The first arc length adjustment value consisting of the average value of the welding current Aw during the period Ta is reduced to 20% to 40%, preferably about 30%, compared with the welding current Aw during the arc period Ta during the first heat input period Th. To do. In this way, the average value of the welding current Aw (Awc1, Awc2) in the arc period Ta of the second heat input period Tc is set in the range of 30 A to 150 A, preferably 40 A to 120 A, and the low heat input. It is preferable to make it.

  The first arc length adjustment value as the base current Awc2 in the arc period Ta of the second heat input period Tc is 25 A or more. If the base current Awc2 is lower than this range, arc breaks occur frequently and the arc becomes unstable. Further, when the base current Awc2 is higher than the peak current Awc1, the effect of suppressing the burnout of the work piece 21 is reduced. In addition, when the average value of the welding current Aw in the arc period Ta of the second heat input period Tc exceeds 150 A, the arc length is increased due to the excessive heat input and the welding wire 21 is burned out. It becomes easy to do.

  Therefore, by controlling within an appropriate range, burn-out can be suppressed, and by reducing heat input, the occurrence of strain is suppressed, and the effect of increasing the gap tolerance, which is the tolerance for the gap, can be obtained. .

  Further, in order to stabilize the periodic arc, the current increase gradient Aws1 and the second current increase gradient Aws2 in the short circuit period Ts of the first heat input period Th, the inflection point, and the short circuit period Ts of the second heat input period Tc. The arc in the arc period Ta is stabilized by changing one or more of the current increase slope Aws1, the second current increase slope Aws2, and the bending point to promote short circuit opening. For example, it is preferable to set and control the bending point of the short-circuit period Ts in a range of 200 A to 400 A. More preferably, it is 300A.

  When this bending point is lower than 200 A, for example, the amount of heat input to the welding wire in the second heat input period Tc decreases, and when the arc length is shortened, the short circuit is not smoothly opened and the arc becomes unstable. . On the other hand, if it is set higher than 400A, the amount of heat input at the moment of transferring the droplet increases, so that spatter increases. The material to be welded as the workpiece 21 and the welding wire 22 can be applied to mild steel, stainless steel, high-tensile material, aluminum material, and the like. It is particularly effective because it is likely to cause burnout and the like.

Note that periodically repeating the first heat input period Th and the second heat input period Tc having a lower heat input amount than the first heat input period Th is one or more first heat input periods Th. As long as one or more second heat input periods Tc are included and repeated.
For example, a plurality of first heat input periods Th and a plurality of second heat input periods Tc that are less than the number of consecutive first heat input periods Th, a plurality of first heat input periods Th It may be one that repeats Th and one second heat input period Tc, one that repeats one first heat input period Th, and one second heat input period Tc.
(Embodiment 2)
The second embodiment relates to a method for controlling the arc length in which the influence of disturbance is suppressed.
In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The main difference from the first embodiment is that the arc length adjustment value further includes a second arc length adjustment value, and is controlled by setting a voltage as the second arc length adjustment value. The operation will be described with reference to FIG.

  In the second embodiment, a set average welding voltage Vs for performing constant voltage control is provided, the set average welding voltage Vs is set in the welding condition setting unit 15 as a second arc length adjustment value of the arc length adjustment value, and welding voltage detection is performed. A welding voltage Vw during arc welding is detected at part 8. The set average welding voltage Vs as the second arc length adjustment value in the first heat input period Th and the second heat input period Tc is obtained in advance experimentally, for example.

  Constant voltage control is performed so that an average welding voltage corresponding to the set average welding voltage Vs is output. When there is a difference between the set average welding voltage Vs and the output average welding voltage, the amount of heat input is reduced in the second heat input period Tc. The welding parameters such as the welding current Aw in the heat input period Th of 1 are dominant. Therefore, it is preferable to mainly adjust and control the welding parameter of the first heat input period Th that is dominant with respect to the output average welding voltage.

  When there is a difference between the set average welding voltage Vs and the output average welding voltage, a change in the bending point of the short-circuit period Ts of the first heat input period Th during the first heat input period Th during arc welding. I do. Further, any one of the predetermined peak current Awa1, the duration Awt1 of the peak current Awa1, the base current Awa2, and the duration Awt2 of the base current Awa2 in the first heat input period Th is changed. Furthermore, the bending point of the short circuit period Ts in the second welding heat input period Tc is changed. Further, any one of predetermined peak current Awc1, base current Awc2, duration Awt2 of peak current Awc1, and duration Awt3 of base current Awc2 in arc period Ta in second welding heat input period Tc is changed. Further, any one of the forward feed amplitude Wap, the reverse feed amplitude Wan, the forward feed cycle Wtp, and the reverse feed cycle Wtn of the welding wire feed speed Wf is changed.

  For example, the bending point of the short-circuit period Ts of the first heat input period Th that affects the short-circuit opening is changed within a range of 20 A or more and 50 A or less with respect to the value set in the welding condition setting unit 15, and set average welding When the average welding voltage output corresponding to the voltage Vs is low, the bending point is raised, and when the average welding voltage output corresponding to the set average welding voltage Vs is high, the bending point is lowered. Thereby, the short circuit state is easily opened, and even when the short circuit is opened and the arc length is increased, the amount of heat input at the time of droplet transfer can be reduced, so that the generation of spatter can be suppressed.

  Furthermore, when the fluctuation of the arc spread in the arc period Ta is large, the peak current Awa1 and the base current Awa2 in the arc period Ta of the first heat input period Th are set to values set in the welding condition setting unit 15. It is changed within the range of 10A to 50A. When the average welding voltage output corresponding to the set average welding voltage Vs is low, the peak current Awa1 and the base current Awa2 are increased in the first heat input period Th. When the output of the average welding voltage corresponding to the set average welding voltage Vs is high, the peak current Awa1 and the base current Awa2 are lowered.

Thereby, the influence of disturbance is suppressed, the fluctuation of the spread of the arc is suppressed, the melting speed of the tip of the welding wire 22 is stabilized, and the arc length is stabilized.
Further, while maintaining the low heat input effect due to the second heat input period Tc, the influence of disturbance is suppressed and the arc length is stabilized.

  Furthermore, when the output of the average welding voltage corresponding to the set average welding voltage Vs cannot be adjusted with the bending point, peak current Awa1 and base current Awa2, the set average welding is performed at the welding wire feed speed Wf. It is preferable to adjust the output of the average welding voltage corresponding to the voltage Vs. In other words, it is preferable not to change the welding wire feed speed Wf in preference to the bending point, the peak current Awa1 and the base current Awa2.

  For example, when the output of the average welding voltage corresponding to the set average welding voltage Vs is low, it is determined that the arc length is shortened, and the reverse feed amplitude Wan or the reverse feed cycle Wtn is increased, or the forward feed amplitude Wap or The forward cycle Wtp is decreased. If the output of the average welding voltage corresponding to the set average welding voltage Vs is high, it is determined that the arc has become longer, and the reverse feed amplitude Wan or the reverse feed cycle Wtn is decreased, or the forward feed amplitude Wap or the forward feed The transmission cycle Wtp is increased. Thereby, the arc length is stabilized.

  However, if the welding wire feed speed Wf is changed solely in preference to the bending point of the welding current Aw, the peak current Awa1 and the base current Awa2, etc., the average welding voltage corresponding to the set average welding voltage Vs will be reduced. If the output is low, it is determined that the arc length has become shorter, and the reverse feed amplitude Wan or the reverse feed cycle Wtn is relatively increased, or the forward feed amplitude Wap or the forward feed cycle Wtp is decreased too much. Will end up. Thereby, since the amount of welding decreases, it becomes difficult to form a bead.

  On the other hand, if the output of the average welding voltage corresponding to the set average welding voltage Vs is high, it is determined that the arc has become longer, and the reverse feed amplitude Wan or the reverse feed cycle Wtn is relatively reduced or forward fed. In the second heat input period Tc in which the heat input is decreased, the heat input for melting the welding wire is insufficient, and the arc is increased. The length becomes unstable.

  As described above, the set average welding voltage as the second arc length adjustment value is set, and constant voltage control is performed so that the average welding voltage corresponding to the set average welding voltage Vs is output. When there is a difference between the set average welding voltage Vs and the output average welding voltage, during arc welding, the bending point of the short-circuit period Ts of the first heat input period Th and further the first heat input period Th At least one of a predetermined peak current Awa1, a duration Awt1 of the peak current Awa1, a base current Awa2, and a duration Awt2 of the base current Awa2 in the arc period Ta is changed.

  As a result, the heat input corresponding to the protruding length of the welding wire 22 is applied, and the average welding voltage is set to the welding parameter of the current waveform Aw so that the average welding voltage corresponding to the set average welding voltage Vs is output. By using and adjusting, for example, constant voltage control can be performed with the set average voltage Vw corresponding to the weld joint and plate thickness, and even if variations such as plate thickness and gap occur, the influence of disturbance is suppressed. The arc length is stabilized.

For example, even in the case where a disturbance such as a target with respect to the work piece 21 occurs such that the weld length of the work piece 21 is long, the thickness or gap varies, and the arc length greatly changes during welding, the above-described problem occurs. Since the constant voltage control is performed, the arc can be stabilized. In particular, it is effective for construction where heat tends to be trapped and melts easily like high-tensile (high-strength steel) materials, and heat input is reduced, so the generation of strain is suppressed, leading to improved welding quality. I can do things.
(Embodiment 3)
The third embodiment relates to an arc length control method in which the influence of disturbance is suppressed.
In the third embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted. The main difference from the first and second embodiments is that the set average welding voltage is set and controlled as the second arc length adjustment value in each of the first heat input period Th and the second heat input period Tc. is there.

  In Embodiment 3, as the second arc length adjustment value, a predetermined set average welding voltage (not shown) corresponding to each of the first heat input period Th and the second heat input period Tc is set in the welding condition setting unit 15. To do. The set average welding voltage to be set is experimentally obtained in advance, for example.

  The welding voltage detection unit 8 detects the welding voltage during arc welding in each of the first heat input period Th and the second heat input period Tc, and during arc welding so as to obtain a desired average welding voltage. The current waveform Aw is changed and controlled. The part where the current waveform Aw is changed is the same as in the second embodiment.

  Thus, each of the first heat input period Th and the second heat input period Tc has the second arc length adjustment value individually, and the first heat input period Th and the second heat input period Tc. The arc length is controlled to be constant during each heat input period. The second arc length adjustment value is a first set average welding voltage corresponding to the first heat input period Th and a second set average welding voltage corresponding to the second heat input period, and constant voltage control. Is to do.

Thereby, since the heat input amount at the time of welding can be managed in each of the first heat input period Th and the second heat input period Tc, each of the first heat input period Th and the second heat input period Tc performed by the user is performed. The adjustment margin of the second arc length adjustment value is improved.
In the present embodiment, since the first heat input period Th and the second heat input period Tc having different heat input amounts are used, it is not preferable to use one average moving voltage for constant voltage control. In other words, it is preferable to use the average moving voltage in each of the first heat input period Th and the second heat input period Tc.

In particular, since the amount of heat input is reduced during the arc period Ta of the second heat input period Tc, the heat input during the first heat input period Th is dominant in the arc length during welding.
Therefore, the welding voltage Vw during arc welding can be detected in each of the first heat input period Th and the second heat input period Tc, and the arc length can be controlled with high accuracy. Note that the second arc length adjustment value in the first heat input period Th that is dominant with respect to the heat input may be mainly adjusted.

  Since the adjustment margin of the second arc length adjustment value is improved, the number of work man-hours for setting the welding conditions is reduced, which can lead to an improvement in productivity. Further, since the arc length can be finely adjusted and the amount of heat input can be reduced with high accuracy, the welded material 21 can be prevented from being burned out or distorted.

  As described above, according to the present invention, in short-circuit welding in which a short circuit and an arc are repeated, the first heat input period Th and the second heat input period Tc having a lower heat input than the first heat input period Th are cycled. Since the heat input can be reduced while maintaining a stable arc, it is possible to realize the suppression of the burn-out of the thin plate welding and the improvement of the gap tolerance.

  Thus, by setting and repeating one or more first heat input periods Th and one or more second heat input periods Tc having a lower heat input amount than the first heat input period Th, a low value is obtained. Switching of heat input for heat input can be set finely. Moreover, while reducing heat input, the change of bead width can be suppressed and a favorable bead appearance can be obtained. The short-circuit arc welding of the present invention has a smaller heat input than pulse arc welding, and can shorten the arc length and reduce the heat input.

  By periodically reducing the welding current during the arc period, the stability of the arc is increased, the heat input is suppressed, and the arc length is shortened. It is possible to improve the welding quality by preventing the burn-off during welding when there is a gap between objects, leading to the improvement of the welding quality and the productivity.

  According to the present invention, in short-circuit welding which repeats a short circuit and an arc, the first heat input period Th and the second heat input period Tc having a lower heat input than the first heat input period Th are periodically repeated. It is possible to reduce the heat input while maintaining a stable arc, to suppress the welding of the thin plate, and to improve the gap tolerance, leading to the improvement of the welding quality and the productivity. This is industrially useful as an arc welding control method for performing short-circuit arc welding while feeding a welding wire as a consumable electrode.

1 Input power 2 Main transformer (transformer)
3 Primary side rectification part 4 Switching part 5 DCL (reactor)
6 Secondary side rectification unit 7 Welding current detection unit 8 Welding voltage detection unit 9 Short circuit detection unit 10 Short circuit / arc detection unit 11 Short circuit release detection unit 12 Output control unit 13 Short circuit control unit 14 Arc control unit 15 Welding condition setting unit 16 Wire Feed speed control unit 17 Wire feed speed detection unit 18 Calculation unit 19 Forward feed / reverse feed switching timing control unit 20 Arc welding apparatus 21 Work piece 22 Welding wire 23 Arc 24 Welding tip

Claims (9)

An arc that periodically repeats a first heat input period composed of a first heat input amount and a second heat input period composed of a second heat input amount with respect to the work piece using a welding wire which is a consumable electrode. An arc welding control method for performing welding,
An arc welding control method in which the arc length during arc welding is controlled based on a preset arc length adjustment value. A second heat input composed of a first heat input period composed of a first heat input amount and a second heat input amount lower than the first heat input amount with respect to an object to be welded using a welding wire which is a consumable electrode. An arc welding control method for performing arc welding that periodically repeats a period,
The first heat input period and the second heat input period each have a short circuit period and an arc period, and the arc length during arc welding is controlled based on a preset arc length adjustment value. Control method. The arc length adjustment value includes a first arc length adjustment value, and the first arc length adjustment value is an average value of a peak current and a base current in the arc period of the second heat input period, or a welding current. The arc welding control method according to claim 1. The arc length adjustment value includes a first arc length adjustment value, and the first arc length adjustment value is an average value of a peak current and a base current in the arc period of the second heat input period, or a welding current. The arc welding control method according to claim 2. The first arc length adjustment value, which is an average value of the welding current during the arc period of the second heat input period, is 20% or more and 40% or less than the welding current of the arc period Ta of the first heat input period. The average value of the welding current during the arc period of the second heat input period is preferably set in the range of 30 A to 150 A, preferably 40 A to 120 A, so as to be preferably reduced to 30%. The arc welding control method described in 1. The arc welding control method according to claim 5, wherein a base current of the arc period of the second heat input period as the first arc length adjustment value is 25A or more. The first heat input period and the second heat input period have a short circuit period and an arc period, respectively.
In the first heat input period or the second heat input period, an inflection point that is a switching point between the current increase slope in the short-circuit period and the second current increase slope is in a range of 200 A to 400 A, and more preferably. The arc welding control method according to claim 3, wherein is 300A. The arc length adjustment value further includes a second arc length adjustment value, a set average welding voltage as the second arc length adjustment value is set, and an average welding voltage corresponding to the set average welding voltage is output. As shown in FIG.
During arc welding, at least one of at least the bending point of the short circuit period, the peak current, the base current, the duration of the peak current, and the duration of the base current in the arc period during the first heat input period The arc welding control method according to claim 4 or 7, wherein: Each of the first heat input period and the second heat input period has the second arc length adjustment value individually, and the second arc length adjustment value is determined during the first heat input period. The corresponding first set average welding voltage and the second set average welding voltage corresponding to the second heat input period, and the respective heat input of the first heat input period and the second heat input period. The arc welding control method according to claim 8, wherein the constant voltage control is performed so that the arc length is constant in each period.