JP2012081501A - Arc welding control method, and arc welding equipment - Google Patents

Abstract

In a welding control method in which a wire feed speed is repeated between forward and reverse feeds in order to reduce spatter, when a short circuit occurs, the short circuit is immediately decelerated from forward feed to reverse feed to actively open the short circuit. However, since a reverse feed is made immediately when a short circuit occurs, there is no amount of pushing into the molten pool by forward feed, and the penetration becomes shallower than in the case of forward feed and short circuit opening. If the welding current is increased and the heat input is increased, the penetration can be deepened, but the wire usage increases due to the increase in the wire feed amount, which increases costs and increases the welding conditions. It is uneconomical because it requires extra.
An arc welding control method for performing short-circuit welding by alternately repeating a short-circuit and an arc while feeding a wire, in the short-circuit period from the occurrence of a short-circuit to the occurrence of an arc, with the time of occurrence of the short-circuit as a time starting point The wire is fed forward until a predetermined time, and the wire is fed backward after the predetermined time has elapsed.
[Selection] Figure 1

Description

  The present invention relates to an arc welding control method and an arc welding apparatus that perform short-circuit welding by repeating short-circuiting and arcing while continuously and automatically feeding a welding wire that is a consumable electrode.

  FIG. 3 is a diagram showing an output waveform in a conventional arc welding control method involving a short circuit, and shows temporal changes in the welding current I, the welding voltage V, and the wire feed speed WS.

  In FIG. 3, in the short-circuit period (Ts) from time t1 to time t2, current control is performed after time t1 in the initial stage of short-circuit occurrence to increase the welding current I, and forward feed as the wire feed speed WS ( The welding wire is fed backward by decelerating from the wire feed speed WS1 which is the forward feed) to the wire feed speed WS3 which is the backward feed (reverse feed).

  In the arc period (Ta) from time t2 to time t3, current control is performed from time t2 in the initial stage of arc generation to increase the welding current I to the peak current IP (for example, 200 A or more), and the wire feed speed WS. Is accelerated from the wire feed speed WS3 to the wire feed speed WS1, and the welding wire is fed forward.

  As described above, in the short-circuit period (Ts), the wire feed is set as the backward feed, whereby the feeding amount of the welding wire fed during the short-circuit period can be reduced, and the wire feed is set as the backward feed. It is possible to generate an arc by opening the short-circuit state in a shorter time than when not. Further, by increasing the welding current to a predetermined peak current by changing the wire feeding from the backward feeding to the forward feeding after the arc is generated, it is possible to stably burn the welding wire and form droplets.

  As a result, it is difficult for a short circuit to occur immediately after the occurrence of an arc, and sputtering can be reduced (see, for example, Patent Document 1).

JP 2007-216218 A

  As shown in FIG. 3, in the conventional arc welding control method described above, when a short circuit occurs at time t1, the wire feed speed WS is immediately changed from the wire feed speed WS1, which is forward feed, as shown in FIG. The speed is reduced to the wire feed speed WS3 which is the reverse feed, and the short circuit is actively opened. However, in this case, since the welding wire is retracted and fed as soon as a short circuit occurs, there is no pushing amount of the welding wire into the molten pool formed in the welding object by the forward feeding of the welding wire. For this reason, the penetration (d1) tends to be shallow as compared with the case where the welding wire is fed backward without being fed backward and the wire is fed forward while the short circuit is opened. Although it varies depending on the welding current, shield gas, joint shape, etc., the amount of penetration becomes approximately 0.5 to 0.9 times shallower. In this case, in order to deepen the penetration, it is necessary to increase the heat input by setting the welding current high again. However, there is a proportional relationship between the welding current and the welding wire feed rate (welding wire feed rate). If the welding current is increased, the welding wire feed rate also increases, and the welding wire feed rate increases, resulting in welding. Since the amount of wire used increases, the cost of the welding wire is increased. In addition, since the electrical energy is required by the amount corresponding to the increased welding current, it is uneconomical.

  In order to solve the above problems, an arc welding control method of the present invention is an arc welding control method in which welding is performed by alternately repeating a short circuit and an arc while feeding a welding wire. In the short-circuit period up to, the welding wire is fed forward until a predetermined time starting from the time of occurrence of the short-circuit, and the welding wire is fed backward after the predetermined time has elapsed.

  Further, in addition to the above, the arc welding control method of the present invention feeds the welding wire forward at a predetermined speed during the arc period from the occurrence of the arc to the occurrence of the short circuit until the predetermined time elapses in the short circuit period. The welding wire is fed forward at a predetermined speed during the arc period.

An arc welding apparatus according to the present invention is an arc welding apparatus that performs welding by repeatedly generating and short-circuiting an arc between a welding wire that is a consumable electrode and an object to be welded, and is a switching element that controls a welding output. When,
A welding voltage detection unit for detecting a welding voltage, a short-circuit / arc detection unit for detecting whether a short-circuit state or an arc state is based on an output of the welding voltage detection unit, and a welding output in a short-circuit state A short-circuit control unit that outputs a control signal, an arc control unit that outputs a control signal for welding output when in an arc state, and the switching element is controlled based on a control signal from the short-circuit control unit or the arc control unit A wire feeding motor controller for feeding the welding wire, a wire feeding motor for feeding the welding wire, and a wire feeding motor control unit for controlling the wire feeding motor based on a signal from the short circuit / arc detecting unit, The wire feed motor control unit outputs a signal for instructing the wire feed speed, and generates a short circuit during the short circuit period from the occurrence of the short circuit to the occurrence of the arc. Time measuring unit for measuring time starting from time, wire feeding speed control for outputting a control signal for controlling the wire feeding motor control unit by inputting outputs of the wire feeding speed instruction unit and the timing unit The wire feeding motor control unit causes the welding wire to be fed forward until a predetermined time starting from the time of occurrence of the short circuit in the short circuit period from the time of occurrence of the short circuit to the time of occurrence of the arc, and the predetermined time has elapsed. Later, the welding wire is fed backward.

  In addition to the above, the wire feed motor control unit in the arc welding device according to the present invention feeds the welding wire forward at a predetermined speed during the arc period from the time of the arc occurrence to the time of the short circuit occurrence. The welding wire is fed forward at a predetermined speed during the arc period until a predetermined time elapses.

  As described above, according to the present invention, the welding wire is fed forward until a predetermined time elapses from the time of occurrence of the short circuit, and the welding wire is fed backward after the predetermined time elapses. The penetration can be increased by the action of pushing the molten pool at the tip of the welding wire that is short-circuited until a predetermined time. Thereby, since the penetration can be increased without increasing the average value of the feeding amount of the welding wire, it is possible to deepen the penetration while suppressing the increase in the cost of the welding wire and the increase in electric energy. . And opening of a short circuit can be accelerated | stimulated by carrying out reverse feed (reverse feed) of a welding wire after progress of predetermined time.

The figure which shows the output waveform in the arc welding control method of Embodiment 1 of this invention. The figure which shows schematic structure of the arc welding apparatus in Embodiment 1 of this invention. The figure which shows the output waveform in the arc welding control method with the conventional short circuit

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

(Embodiment 1)
FIG. 1 is a diagram showing output waveforms in an arc welding control method performed by the arc welding apparatus of the present embodiment, and shows temporal changes in welding current I, welding voltage V, and wire feed speed WS.

  In the short-circuit period (Ts) from time t1 to time t2 shown in FIG. 1, current control is performed from time t1 in the initial stage of short-circuit occurrence to increase the welding current I with a predetermined slope. Further, even if a short circuit occurs at time t1, the wire feed speed WS is maintained at the wire feed speed WS1 during the arc period until the predetermined time tb elapses and time t7 is reached (normal feed). Send). When the time t7 is reached, the wire feeding speed WS is decelerated to the wire feeding speed WS3 and set to backward feeding (reverse feeding). In addition, immediately before the end of the short-circuit period, that is, immediately before time t2, as is conventionally known, control is performed to detect the constriction of the molten welding wire and sharply reduce the welding current I.

  In the arc period (Ta) from time t2 to time t3, current control is performed from time t2 in the initial stage of arc generation to increase the welding current I with a predetermined slope, and the peak current IP (for example, 200 A or more) of the welding current I is increased. ) Until it becomes. Further, the wire feeding speed WS is accelerated from the wire feeding speed WS3 that is the backward feeding to the wire feeding speed WS1 that is the forward feeding.

  Even if a short circuit occurs, the wire is fed forward at the wire feed speed WS1 until the predetermined time tb elapses. Therefore, the wire feed speed WS1 × the predetermined time tb (the hatched portion of the wire feed speed WS in FIG. 1). The wire amount indicated by is fed even after the occurrence of a short circuit and pushes in the molten pool formed in the welding object. For this reason, since the molten metal in the molten pool is pushed toward the forward feeding direction (forward feeding direction) of the welding wire, the penetration depth of the welding object is the penetration in FIG. 3 showing an example of a conventional arc control method. With respect to the depth d1, it becomes deep like the penetration depth d2 shown in FIG. Although it differs depending on the welding current, shield gas, joint shape, etc., the amount of penetration becomes approximately 1.1 to 1.5 times deeper.

  Here, the longer the predetermined time tb is, the deeper the penetration is due to an increase in the pushing amount of the molten pool. However, if it is too long, the unmelted solid portion at the tip of the welding wire comes into contact with the solid portion (unmelted welding object) at the bottom of the melting pool, and the welding object is pushed and moved. And the position shift of a welding target object generate | occur | produces and deviation | shift of a weld bead generate | occur | produces in subsequent welding. For this reason, the value of the predetermined time tb is desirably a value greater than 0 obtained by experiments and demonstrations and up to about 5 ms.

  Moreover, in FIG. 1, the wire feed speed WS at the predetermined time tb shows the same example as the wire feed speed WS1, which is the wire feed speed during the arc period. However, since the wire feeding speed of the forward feeding has a pushing action, there is no problem even if the wire feeding speed of the forward feeding is different from the wire feeding speed WS1 during the arc period. However, when welding is performed, it is desirable that the change in the wire feed speed WS is small, and the wire feed speed WS at the predetermined time tb is set to be the wire feed speed WS from the viewpoint of easy control of the wire feed speed WS. It is desirable to make it the same as the feeding speed WS1.

  In addition, since the required penetration differs for each welding site, it is possible to obtain proper penetration by adjusting the value of the predetermined time tb for each welding site together with the adjustment of the set welding current and the set welding voltage. .

  Here, the arc welding apparatus for performing the arc welding control as described above will be described with reference to FIG.

  In FIG. 2, an arc welding apparatus includes a primary rectification unit 2 that rectifies power input from an input power supply 1, a switching element 3 for controlling the welding output using the output of the primary rectification unit 2, and a switching element. 3 controls the operation of the switching element 3, the transformer 4 that transforms the output of the transformer 3, the secondary rectifier 5 that rectifies the output of the transformer 4, the DCL 6 that is an inductance for smoothing the output of the secondary rectifier 5. Drive unit 7, welding voltage detection unit 8 that detects the welding voltage, welding current detection unit 9 that detects the welding current, and in the arc state based on the detection result of welding voltage detection unit 8 A short circuit / arc detection unit 10 that detects whether there is a short circuit, a short circuit control unit 11 that outputs a control signal of welding output to the drive unit 7 in the case of a short circuit state based on the detection result of the short circuit / arc detection unit 10, An arc control unit 12 for outputting a welding output control signal to the drive unit 7 in the case of an arc state based on the detection result of the envelope / arc detection unit 10 and a wire feed motor control unit for controlling the feeding of the welding wire 19 13, a welding condition setting unit 14 for setting welding conditions such as a set welding current, a diameter of the welding wire, and a welding method such as CO 2 and MAG, a welding condition, a predetermined time tb, a welding condition, a wire feed speed, and the like. Are stored in association with each other.

  The wire feeding motor control unit 13 includes a wire feeding speed instruction unit 16 for controlling the feeding speed of the welding wire 19, a time measuring unit 17 for measuring time, and a wire feeding speed instruction unit 16 for measuring time. A wire feed speed control unit 23 that outputs a signal for controlling the wire feed based on the output of the unit 17 is provided.

  One end of the welding output is supplied to the welding wire 19 via the tip 20, the other end of the welding output is supplied to the welding object 22, and a welding arc is generated between the tip portion of the welding wire 19 and the welding object 22. 21 occurs. Further, the welding wire 19 is fed by a wire feeding motor 18.

  Moreover, the welding voltage detection part 8 is connected between the power supply output terminals for welding, and outputs the signal corresponding to the detected voltage. The short-circuit / arc detection unit 10 determines whether the welding output voltage is equal to or higher than a certain value based on the signal from the welding voltage detection unit 8, and the welding wire 19 is contact-short-circuited to the welding object 22 based on the determination result. It is determined whether it is a short-circuited state, or an arc state in which the welding arc 21 is generated in a non-contact state, and a determination signal is output.

  A predetermined time tb is selected from the storage unit 15 based on the welding conditions set and input to the welding condition setting unit 14 and output to the time measuring unit 17. Further, based on the welding conditions set and input to the welding condition setting unit 14, the wire feeding speed WS1 that is forward feeding and the wire feeding speed WS3 that is backward feeding are selected from the storage unit 15, and the wire feeding is performed. It is output to the speed instruction unit 16.

  Next, the feed control of the welding wire 19 after the determination by the short circuit / arc detection unit 10 will be described.

  First, the case where the signal from the short-circuit / arc detection unit 10 is a short-circuit period (Ts) indicating a short-circuit determination will be described.

  The wire feed motor control unit 13 includes a wire feed speed instruction unit 16, a timer unit 17, and a wire feed speed control unit 23. When the signal from the short circuit / arc detection unit 10 is a short circuit determination signal indicating the short circuit period (Ts), the time measuring unit 17 starts measuring time. Then, when a predetermined time tb set in advance elapses, the timer unit 17 outputs a signal indicating that the predetermined time tb has elapsed to the wire feed speed control unit 23.

  When the signal from the short-circuit / arc detection unit 10 is a short-circuit determination signal indicating the short-circuit period (Ts), the wire feed speed instruction unit 16 and the wire feed speed WS1 that is forward feed (forward feed) and the reverse feed The wire feeding speed WS3 which is feeding (reverse feeding) is output to the wire feeding speed control unit 23.

  The wire feed speed control unit 23 inputs the output of the wire feed speed instruction unit 16 and the output of the time measuring unit 17, and until receiving a signal indicating that the predetermined time tb has elapsed from the time measuring unit 17, A control signal is output to the wire feed motor 18 so as to control the feed speed WS to the wire feed speed WS1. The wire feed motor 18 that has received the control signal from the wire feed motor control unit 13 feeds the welding wire 19 so that the wire feed speed WS becomes the wire feed speed WS1 that is forward feed. Control. When the wire feeding speed control unit 23 receives a signal indicating that the predetermined time tb has elapsed from the time measuring unit 17, the wire feeding motor 18 is configured to control the wire feeding speed WS to the wire feeding speed WS3. Output a control signal. Then, the wire feeding motor 18 that has received the control signal from the wire feeding motor control unit 13 feeds the welding wire 19 so that the wire feeding speed WS becomes the wire feeding speed WS3 which is the backward feeding. Control.

  Next, the case where the signal from the short-circuit / arc detection unit 10 is an arc period (Ta) in which a signal indicating arc determination is described.

  When the signal from the short-circuit / arc detection unit 10 is an arc determination signal indicating an arc period (Ta), the wire feed speed instruction unit 16 sets the wire feed speed WS1 that is forward feed (forward feed) to the wire. Output to the feeding speed control unit 23. Note that the timer 17 does not operate during the arc period (Ta).

  The wire feed speed control unit 23 receives the output of the wire feed speed instruction unit 16 and outputs a control signal to the wire feed motor 18 so as to control the wire feed speed WS to the wire feed speed WS1. Then, the wire feeding motor 18 that has received the control signal from the wire feeding motor control unit 13 controls the feeding of the welding wire 19 so that the wire feeding speed WS becomes the wire feeding speed WS1.

  Next, control of the welding output after the determination of the short circuit / arc detection unit 10 will be described below.

  Control of the welding output during the short-circuit period (Ts) is performed based on the short-circuit control unit 11. Control of the welding output during the arc period (Ta) is performed based on the arc control unit 12.

  When a signal indicating a short circuit period (Ts) is received from the short circuit / arc detection unit 10, the short circuit control unit 11 outputs a control signal to the drive unit 7, and based on this control signal, the drive unit 7 switches the switching element 3. Is operated to control the welding output during the short circuit period (Ts).

  When a signal indicating the arc period (Ta) is received from the short-circuit / arc detection unit 10, the arc control unit 12 outputs a control signal to the drive unit 7, and the drive unit 7 is switched on based on this control signal. By operating the element 3, the welding output during the arc period (Ta) is controlled.

  As described above, according to the arc welding apparatus and the arc welding control method of the present embodiment, in the short circuit period (Ts), the wire feed is performed until the predetermined time tb elapses from the time t1 when the short circuit occurs. The welding wire 19 is fed forward at the wire feeding speed WS1 during the arc period without decelerating the feeding speed WS, and after the predetermined time tb has elapsed, the wire feeding speed WS is controlled to the wire feeding speed WS3 to move backward. Let it be sent. Thus, in the short circuit period (Ts), the welding wire 19 is fed forward (forward) from the time of occurrence of the short circuit to the predetermined time tb. For this reason, until the predetermined time tb elapses from time t1 when the short circuit occurs, the weld pool 22 is short-circuited and the molten pool formed in the welding object 22 is pushed in by the forward feed welding wire 19, It becomes possible to increase the penetration of the welding object 22. Thereby, since it is possible to increase the penetration without increasing the set value of the welding current I, that is, without increasing the average value of the feeding amount of the welding wire 19, the amount of welding wire 19 used is suppressed and welding is performed. An increase in cost applied to the wire 19 can be suppressed, and the penetration of the welding object 22 can be deepened, so that good welding can be realized.

  According to the present invention, the welding wire is fed forward until a predetermined time elapses from the time of occurrence of the short circuit, and the welding wire is fed backward after the predetermined time elapses. It is possible to achieve good welding by increasing the penetration by the action of pushing the molten pool at the tip of the welding wire that is short-circuited, and short-circuiting while continuously feeding the welding wire as a consumable electrode automatically It is industrially useful as an arc welding control method and arc welding apparatus for performing short-circuit welding by repeating arc and arc.

V Welding voltage I Welding current IP Peak current WS Wire feed speed WS1 Wire feed speed WS3 Wire feed speed tb Predetermined time 1 Input power source 2 Primary rectifier 3 Switching element 4 Transformer 5 Secondary rectifier 6 DCL
DESCRIPTION OF SYMBOLS 7 Drive part 8 Welding voltage detection part 9 Welding current detection part 10 Short circuit / arc detection part 11 Short circuit control part 12 Arc control part 13 Wire feed motor control part 14 Welding condition setting part 15 Storage part 16 Wire feed speed instruction | indication part 17 Timekeeping section 18 Wire feed motor 19 Welding wire 20 Tip 21 Welding arc 22 Welding object 23 Wire feed speed control section Ta arc period Ts Short circuit period

Claims (4)

An arc welding control method for performing welding by alternately repeating a short circuit and an arc while feeding a welding wire,
An arc welding control method in which, during a short circuit period from the occurrence of a short circuit to the occurrence of an arc, the welding wire is fed forward until a predetermined time starting from the time of occurrence of the short circuit, and the welding wire is fed backward after the predetermined time has elapsed. . The welding wire is fed forward at a predetermined speed during an arc period from the occurrence of an arc to the occurrence of a short circuit, and the welding wire is fed forward at a predetermined speed during the arc period until a predetermined time elapses in the short circuit period. The arc welding control method according to claim 1. An arc welding apparatus that performs welding by repeatedly generating and short-circuiting an arc between a welding wire that is a consumable electrode and a welding object,
A switching element for controlling the welding output;
A welding voltage detector for detecting the welding voltage;
A short-circuit / arc detection unit for detecting whether a short-circuit state or an arc state based on an output of the welding voltage detection unit;
A short-circuit control unit that outputs a control signal of welding output when in a short-circuit state;
An arc control unit that outputs a control signal of welding output when in an arc state;
A drive unit for controlling the switching element based on a control signal from the short-circuit control unit or the arc control unit;
A wire feed motor for feeding the welding wire;
A wire feed motor controller that controls the wire feed motor based on a signal from the short circuit / arc detector;
The wire feed motor control unit outputs a signal for instructing the wire feed speed, and measures the time starting from the occurrence of the short circuit in the short circuit period from the occurrence of the short circuit to the occurrence of the arc. A wire feeding speed control unit that outputs a control signal for controlling the wire feeding motor control unit by inputting the output of the time measuring unit, the wire feeding speed instruction unit, and the timing unit;
The wire feeding motor control unit feeds the welding wire forward until a predetermined time from the time of occurrence of the short circuit to a predetermined time in a short circuit period from the time of occurrence of the short circuit to the time of occurrence of the arc. Arc welding equipment that feeds back. The wire feed motor control unit feeds the welding wire forward at a predetermined speed during the arc period from the occurrence of the arc to the occurrence of the short circuit, and the predetermined speed during the arc period until the predetermined time elapses during the short circuit period. The arc welding apparatus according to claim 3, wherein the welding wire is fed forward.

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