KR102259226B1 - Arc welding method - Google Patents

Abstract

In spray transfer welding, penetration is deepened.
During the first period (T1), the first output voltage (E1) and the first welding current (Iw1) are output, and during the second period (T2), the second output voltage (E2) and the second welding current (Iw2) are output. And, during the third period (T3), the third output voltage (E3) and the third welding current (Iw3) are output, 0<E2<E3<E1, 0<Iw2<Iw3<Iw1, and the rate of change of the welding current When it is less than this reference rate of change, the first output voltage E1 is increased and/or the second output voltage E2 is decreased. The molten metal immediately under the wire is made thin by the first period (T1), the arc is concentrated under the wire by the second period (T2), and the molten paper is concentrated and heated by the third period (T3). After that, the melted paper is calmed. By modifying the output voltages E1 and E2, deep penetration can be formed without being affected by the inductance value of the welding cable, and high quality can be achieved.

Description

Arc welding method {ARC WELDING METHOD}

The present invention relates to a high quality arc welding method in which welding wire is supplied and welded according to the spray transition state.

Mug welding using a solid wire using a mixed gas of argon gas and carbon dioxide as a shielding gas, arc welding using a flux-containing wire using a carbon dioxide gas as a shielding gas, and a flux-containing wire for self-shielding without using a shielding gas. In self-shielded arc welding and the like to be used, the volume transfer mode is the spray transfer mode. In the spray transfer mode, the tip of the welding wire is melted by arc heat to form fine particles and transfer to the molten paper. In the spray transfer mode, the volume does not short-circuit transfer, but transfers by free fall.

In arc welding by spray transfer mode (hereinafter referred to as spray transfer welding), a welding power source having a constant voltage characteristic is used, and a welding wire is supplied at a constant speed. In spray transfer welding, there is a characteristic that the amount of sputtering is small, and the appearance of the bead is also improved. On the other hand, in spray transfer welding, since the arc length becomes longer than that of short transfer welding, and the arc becomes wider, penetration becomes shallow. This point may be a problem in terms of welding quality depending on the work. Hereinafter, a conventional spray transfer welding will be described with reference to the drawings.

5 is a voltage/current waveform diagram in a general spray transfer welding. (A) of this figure shows the time change of the output voltage setting signal (Er) for setting the output value of the constant voltage characteristic of the welding power source, and (B) of this figure is the welding voltage (Vw) applied between the welding wire and the base material. The time change is shown, and (C) of this figure shows the time change of the welding current Iw which conducts an arc. Hereinafter, it demonstrates with reference to this drawing.

As shown in Fig. (A), the output voltage setting signal Er is set to a constant value. As shown in (B) of this figure, although the welding voltage Vw slightly fluctuates up and down, it becomes a substantially constant value. As shown in Fig. (C), the welding current Iw is also slightly fluctuating up and down, but has a substantially constant value. The instantaneous value of the welding voltage Vw is set by the output voltage setting signal Er. The average value of the welding current Iw is set by the feeding speed of the welding wire.

In the invention of Patent Document 1, in spray transfer welding and globular transfer welding, by periodically changing the output voltage of the welding power source at a frequency of 100 Hz or more and 600 Hz or less, the welding current is changed within a current amplitude of 20 A or more and 100 A or less. Change and weld.

Japanese Patent Publication No. 2007-229775

Accordingly, it is an object of the present invention to provide an arc welding method capable of improving quality by deepening penetration in spray transfer welding.

In order to solve the above-described problem, the invention of claim 1,

In the arc welding method of supplying a welding wire, outputting an output voltage from a welding power source, energizing a welding current, and welding according to a spray transition form,

During the first period, the first output voltage E1 is output to conduct the first welding current Iw1, and during the second period, the second output voltage E2 is output to conduct the second welding current Iw2, During the third period, the third output voltage E3 is output to conduct the third welding current Iw3, 0<E2<E3<E1, 0<Iw2<Iw3<Iw1, and the first to the first period. Repeat 3 periods,

Detects a rate of change of the welding current when switching each period of the first period to the third period, and when the rate of change is less than a predetermined reference rate of change, the first output voltage E1 increases and/or the second 2 It is an arc welding method characterized by reducing the output voltage E2.

The invention of claim 2 is an arc welding method according to claim 1, wherein an alarm is issued when the rate of change is less than the reference rate of change.

The invention of claim 3 is the arc welding method according to claim 1 or 2, wherein when the rate of change is less than the reference rate of change, the first period and/or the second period are lengthened.

According to the present invention, during the first period, a large arc pressure acts on the molten paper, and the molten paper becomes a concave shape with a concave immediately under the wire, and the molten metal immediately under the wire becomes thin. Subsequently, during the second period, the arc shape becomes constricted, and the arc is concentrated in a portion of the molten metal immediately under the wire in a thin state. Subsequently, during the third period, in the first half, the concave portion of the molten paper is concentrated and heated by the arc, and in the second half, since the arc pressure is constant, the concave portion of the molten paper disappears and becomes a calm state. In the present invention, by repeating these first to third periods, penetration can be deepened and high quality can be achieved in spray transfer welding. Further, in the present invention, since the inductance value of the welding cable is large, when the rate of change of the welding current is small and is less than the reference rate of change, the first output voltage value E1 increases and/or the second output voltage E2 ) Decreases, it is possible to increase the rate of change of the welding current. For this reason, it is not affected by the inductance value of the welding cable, and the above effect can be exhibited.

1 is a block diagram of a welding power source for performing the arc welding method according to Embodiment 1 of the present invention.
Fig. 2 is a timing chart of each signal in the welding power supply of Fig. 1 showing the arc welding method according to the first embodiment of the present invention.
3 is a block diagram of a welding power source for performing the arc welding method according to Embodiment 2 of the present invention.
Fig. 4 is a timing chart of each signal in the welding power supply of Fig. 3 showing the arc welding method according to the second embodiment of the present invention.
5 is a voltage/current waveform diagram in a general spray transfer welding in the prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]

1 is a block diagram of a welding power source for performing the arc welding method according to Embodiment 1 of the present invention. Hereinafter, each block will be described with reference to the drawings.

The power supply main circuit PM receives a commercial power supply (not shown) such as a three-phase 200V as input, performs output control by inverter control using a voltage error amplification signal Ev, which will be described later, and adjusts the output voltage E. Print it out. This power supply main circuit (PM) is not shown, but a primary rectifier circuit that rectifies commercial power, a capacitor that smoothes rectified direct current, an inverter circuit that converts smoothed direct current into high-frequency alternating current, and a voltage suitable for arc welding of high-frequency alternating current. A high-frequency transformer stepped down to a value, a secondary rectifying circuit rectifying the stepped down high-frequency AC, and a driving circuit for driving the inverter circuit by performing modulation control such as PWM control using the voltage error amplifying signal Ev as an input, and have. This power supply main circuit PM serves as a constant voltage source, is subjected to constant voltage control with an output voltage control setting signal Ecr described later as a target value, and outputs an output voltage E. Reactor WL smoothes this output voltage E. Thus, the output voltage E is the voltage before being smoothed by the reactor WL.

The welding wire 1 receives the inside of the welding torch 4 by the rotation of the feed roll 5 coupled to the feed motor (not shown), and the arc 3 is generated between the base material 2 so that welding is not possible. Done. A welding voltage Vw is applied between the power supply chip (not shown) in the welding torch 4 and the base material 2, and the welding current Iw is energized in the arc 3. One output terminal (not shown) of the welding power source and the welding torch 4 are connected by a welding cable 6, and the other output terminal (not shown) of the welding power source and the base material 2 are connected to the welding cable 7 ). The summed inductance value of the welding cables 6 and 7 is Lc (µH). The welding wire 1 is welded with an electrode minus polarity (EN) or an electrode plus polarity (EP), depending on the type.

The output voltage setting circuit ER outputs a predetermined output voltage setting signal Er. The voltage increase value setting circuit EUR outputs a predetermined voltage increase value setting signal Eur. The voltage decrease value setting circuit EDR outputs a predetermined voltage decrease value setting signal Edr.

The first period setting circuit T1R outputs a predetermined first period setting signal T1r. The second period setting circuit T2R outputs a predetermined second period setting signal T2r. The third period setting circuit T3R outputs a predetermined third period setting signal T3r.

The output voltage control setting circuit ECR includes the output voltage setting signal Er, the voltage increasing value setting signal Eur, the voltage decreasing value setting signal Edr, the first period setting signal T1r, and the first period setting signal T1r. 2 A period setting signal (T2r), the third period setting signal (T3r), and a rate of change determination signal (Sd) to be described later are input, the following processing is performed, and the output voltage control setting signal (Ecr) and the period signal (Sp) are input. ) Is displayed.

1) During the first period T1 determined by the first period setting signal T1r from the start of the first period, Ecr=Er+Eur is output, and the first period in the first period The output voltage control set value of (T1) is stored as Ecr(1,1). Also, during this period, Sp=1 is output.

2) Subsequently, during the second period T2 determined by the second period setting signal T2r, Ecr = Er-Edr is output, and the second period T2 in the first period is output. It is stored as the voltage control set value Ecr(1,2). Also, during this period, Sp=2 is output.

3) Subsequently, during the third period T3 determined by the third period setting signal T3r, Ecr=Er is output. Also, during this period, Sp=3 is output.

4) During the first period T1 determined by the first period setting signal T1r from the start of the nth period, the rate of change determination signal Sd at the start of the nth first period T1 When is low level, Ecr=Ecr(n-1,1) is output, and when is high level, Ecr=Ecr(n-1,1)+Δu is output. Then, it is stored as the output voltage control set value Ecr(n,1) in the first period T1 in the nth cycle. Δu is a correction amount, and is a value of a predetermined amount. Also, during this period, Sp=1 is output.

5) Subsequently, during the second period T2 determined by the second period setting signal T2r, when the rate of change determination signal Sd at the start of the n-th first period T1 is at a low level, Ecr =Ecr(n-1,2) is output, and at high level, Ecr=Ecr(n-1,2)-Δd is output. Then, it is stored as the output voltage control set value Ecr(n,2) in the second period T2 in the nth cycle. Δd is a correction amount and is a value of a predetermined amount. Also, during this period, Sp=2 is output.

6) Subsequently, during the third period T3 determined by the third period setting signal T3r, Ecr=Er is output regardless of the change rate determination signal Sd. Also, during this period, Sp=3 is output.

7) Repeat the treatments 4) to 6) above.

In the output voltage control setting circuit ECR, the output voltage control setting signal Ecr when the rate of change determination signal Sd is at a high level increases by ΔU from the value of the previous period during the first period T1. , During the second period T2, the value of the previous period is decreased by ΔD, and during the third period T3, the value of the output voltage setting signal Er does not change as it is.

The output voltage detection circuit ED detects the output voltage E, smoothes the ripple caused by the inverter frequency, and outputs an output voltage detection signal Ed. The voltage error amplification circuit EV amplifies an error between the output voltage control setting signal Ecr(+) and the output voltage detection signal Ed(-), and outputs a voltage error amplification signal Ev. The welding power supply is controlled at a constant voltage by this voltage error amplifying circuit EV.

The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The rate of change determination circuit SD receives the current detection signal Id and the period signal Sp as inputs, and detects the rate of change of the current detection signal id from the time point when Sp=3 to Sp=1, When this rate of change is less than the predetermined reference rate of change, it becomes a high level, and when it is above, the rate of change discrimination signal Sd, which becomes a low level, is output at the time when Sp=2 is changed. In this circuit, the rate of change of the current detection signal Id from the time point when Sp=1 to Sp=2 or the time point at which Sp=2 to Sp=3 is changed is detected and compared with the corresponding reference rate of change. do. When the length of the welding cable (6, 7) is lengthened or the inductance value (Lc) of the welding cable is increased due to the length of the welding cable (6, 7) The rate of change of the current Iw becomes gentle. With this circuit, it is determined that the rate of change of the welding current Iw at the time of switching each period of the first period to the third period becomes more gentle than a predetermined reference rate of change.

The alarm circuit AR receives the rate-of-change discrimination signal Sd as an input, and generates an alarm when the rate-of-change discrimination signal Sd = High level. The alarm is performed by lighting an indicator light, sounding an alarm sound, or outputting an alarm signal to the outside.

Fig. 2 is a timing chart of each signal in the welding power supply of Fig. 1 showing the arc welding method according to the first embodiment of the present invention. (A) of this figure shows the time change of the output voltage control setting signal (Ecr), (B) of this figure shows the time change of the welding voltage (Vw), and (C) of this figure shows the time of the welding current (Iw) The change is shown, and (D) of this figure shows the time change of the change rate discrimination signal Sd. Hereinafter, it demonstrates with reference to this drawing.

In this figure, in the period from the start of welding to the time t4, since the inductance value Lc of the welding cable is small, the rate of change of the welding current Iw becomes more than the reference rate of change, as shown in (D) of this figure. Likewise, the rate of change determination signal Sd remains at the low level. On the other hand, the period after time t4 is a case where the wiring of the welding cable is changed and the inductance value Lc is increased. Since the inductance value Lc of the welding cable is determined according to the installation environment of the welding device, it is seldom changed during welding. In this drawing, in order to make the operation of this embodiment easier to understand, it is assumed that the inductance value Lc changes during welding.

As shown in Fig. 1A, the output voltage control setting signal Ecr is a waveform that periodically vibrates by the output voltage control setting circuit ECR of Fig. 1. As shown in FIG. (D), the rate of change determination signal Sd is at a low level before the time t1, and the start time t1 of the first period T1 is also at a low level. Therefore, as shown in (A) of this figure, the output voltage control setting signal Ecr is set to the output voltage setting signal Er during the first predetermined period T1 of time t1 to t2. It becomes the value obtained by adding the signal Eur, and becomes the value obtained by subtracting the voltage reduction value setting signal Edr from the output voltage setting signal Er during the second predetermined period T2 of the times t2 to t3, and the time t3 During the third predetermined period T3 from t4 to t4, the value of the output voltage setting signal Er is obtained. Here, Er>0, Eur>0, Edr>0, Ecr>0.

The output voltage E is set by the output voltage control setting signal Ecr, resulting in substantially the same rectangular waveform. Hereinafter, the output voltage E of the first period T1 is described as the first output voltage E1, the output voltage E of the second period T2 is described as the second output voltage E2, The output voltage E in the third period T3 is described as the third output voltage E3.

As shown in (B) of this figure, the welding voltage Vw becomes a vibration waveform because the output voltage E is a vibration waveform, and during the first period T1 of the times t1 to t2, the third welding voltage value ( Vw3) increases with a slope to become a first welding voltage value (Vw1) of an approximately constant value, and during the second period (T2) of time t2 to t3, decreases with a slope from the first welding voltage value (Vw1) It becomes the second welding voltage value Vw2 of an approximately constant value, and during the third period T3 of the time t3 to t4, the third welding voltage increases with a slope from the second welding voltage value Vw2 to approximately a constant value. It becomes the value (Vw3). The first welding voltage value Vw1 is set by Er+Eur, the second welding voltage value Vw2 is set by Er-Edr, and the third welding voltage value Vw3 is set by Er.

As shown in (C) of this figure, the welding current Iw is determined by the welding voltage Vw and the arc load, and since the welding voltage Vw is vibrating, it becomes a vibration waveform. During one period (T1), the third welding current value (Iw3) increases with a slope to become a first welding current value (Iw1) having an approximately constant value, and during the second period (T2) of the times t2 to t3, the 1 It decreases with a slope from the welding current value Iw1 to become the second welding current value Iw2 of an approximately constant value, and during the third period T3 of the times t3 to t4, from the second welding current value Iw2 It increases with an inclination, and becomes the 3rd welding current value Iw3 of an approximately constant value. Here, it is 0<Iw2<Iw3<Iw1. Since the rate of change of the welding current Iw during the first period T1 is equal to or greater than the reference rate of change, the rate of change discrimination signal Sd does not change as it is at the low level, as shown in FIG.

As shown in FIG. (D), the rate of change determination signal Sd at the start time t4 of the first period T1 is at a low level. For this reason, as shown in (A) of this figure, the output voltage control setting signal Ecr becomes the same value as the previous period, and during the first period T1 of the times t4 to t5, it becomes Er+Eur, and the time During the second period T2 of t5 to t6, it becomes Er-Edr, and during the third period T3 of the time t6 to t7, it becomes Er.

Since the inductance value Lc of the welding cable increases from the time t4, the slope (change rate) of the welding voltage Vw becomes gentle as shown in (B) of this figure. For this reason, the welding voltage Vw gradually increases during the first period T1 of the times t4 to t5 and ends during the increase, and gradually decreases during the second period T2 of the times t5 to t6 and decreases during the decrease. The period ends. During the third period T3, it gradually increases and becomes the third welding voltage value Vw3 having a substantially constant value.

Similarly, as shown in FIG. (C), the slope (change rate) of the welding current Iw also becomes gentle. For this reason, the welding current Iw gradually increases during the first period T1 of the times t4 to t5, and the period ends during the increase, and gradually decreases and decreases during the second period T2 of the times t5 to t6. The period ends on the way. During the third period T3, it gradually increases and becomes the third welding current value Iw3 of a substantially constant value. That is, the amplitude of the welding current Iw in the first period T1 and the second period t2 decreases. Here, since the rate of change of the welding current Iw during the first period T1 becomes less than the reference rate of change, the rate of change determination signal Sd changes to a high level at time t5 as shown in (D) of this figure. .

As shown in FIG. (D), the rate of change determination signal Sd at the start time t7 of the first period T1 is at a high level. Therefore, as shown in (A) of this figure, the output voltage control setting signal Ecr becomes a value corrected from the value of the previous period, and during the first period T1 of the times t7 to t8, Er+Eur+ It becomes the value obtained by adding Δu to the value of Δu and the previous period, and becomes the value obtained by subtracting Δd from the value of Er-Edr-Δd and the previous period during the second period (T2) of the times t8 to t9, and the times t9 to t10 During the third period (T3) of, the value of Er and the previous period remains as it is.

From time t4, the inductance value Lc of the welding cable is increasing, but the value of the output voltage control setting signal Ecr increases during the first period T1, so that the first output voltage E1 increases, and the second period T2. ), since the value of the output voltage control setting signal Ecr decreases and the second output voltage E2 decreases, the slope (change rate) of the welding voltage Vw is, as shown in (B) of this figure, It is gentler than before time t4, but becomes more rapid than the period of time t4 to time t7. For this reason, the welding voltage Vw has a slope from the third welding voltage value Vw3 to the vicinity of the first welding voltage value Vw1 which is a value before the time t4 during the first period T1 of the time t7 to t8. Increases, and during the second period T2 of the times t8 to t9, the slope has a slope from the vicinity of the first welding voltage value Vw1 and decreases to the vicinity of the second welding voltage value Vw2, which is a value before the time t4, and decreases from the time t9 to During the third period T3 of t10, the slope increases from the vicinity of the second welding voltage value Vw2 to a substantially constant third welding voltage value Vw3.

Similarly, as shown in Fig. (C), the slope (rate of change) of the welding current Iw is gentler than before the time t4, but becomes more rapid than the period of the time t4 to t7. Therefore, the welding current Iw has a slope from the third welding current value Iw3 to the vicinity of the first welding current value Iw1 which is a value before the time t4 during the first period T1 of the time t7 to t8. Increases, and during the second period T2 of the time t8 to t9, it has a slope from the vicinity of the first welding current value Iw1 and decreases to the vicinity of the second welding current value Iw2, which is a value before the time t4, and decreases from the time t9 to During the third period T3 of t10, the slope increases from the vicinity of the second welding current value Iw2 to a substantially constant third welding current value Iw3. That is, the amplitude of the welding current Iw in the first period T1 and the second period t2 becomes substantially the same as before the time t4. Here, since the rate of change of the welding current Iw during the first period T1 becomes equal to or greater than the reference rate of change, the rate of change determination signal Sd changes to a low level at time t8 as shown in (D) of this figure. .

As shown in FIG. (D), the rate of change determination signal Sd at the start time t10 of the first period T1 is at a low level. Therefore, as shown in (A) of this figure, the output voltage control setting signal Ecr becomes the same value as the value of the previous period, and during the first period T1 of the times t10 to t11, Er+Eur+Δu And Er-Edr-?d during the second period T2 of the times t11 to t12, and Er during the third period T3 of the times t12 to t13.

From time t4, the inductance value Lc of the welding cable is increasing, but the value of the output voltage control setting signal Ecr increases during the first period T1, so that the first output voltage E1 increases, and the second period ( Among T2), since the value of the output voltage control setting signal Ecr increases and the second output voltage E2 decreases, as shown in (B) of this figure, the slope (change rate) of the welding voltage Vw is It becomes the same as the previous cycle. For this reason, the welding voltage Vw becomes substantially the same waveform as the previous period.

Similarly, as shown in Fig. (C), the slope (change rate) of the welding current Iw is also the same as in the previous period. For this reason, the welding current Iw becomes substantially the same waveform as the previous period. That is, the amplitude of the welding current Iw in the first period T1 and the second period t2 becomes substantially the same as before the time t4. Here, since the rate of change of the welding current Iw during the first period T1 becomes equal to or greater than the reference rate of change, the rate of change determination signal Sd remains at the low level, as shown in FIG.

After this, the periodic operation of the times t10 to t13 is repeated. In this figure, although the case where the correction of the output voltage control setting signal Ecr is only one cycle from the time t7 to t10 is illustrated, there are cases where the change rate of the welding current Iw is continued for a plurality of cycles until the rate of change is equal to or greater than the reference rate of change. . The above-described correction amounts [Delta]u and [Delta]d are set to about 1 to 3V. If this value is too large, the welding condition becomes unstable, and if it is too small, it takes time to correct, and the welding quality deteriorates during the correction period. During the modified first period T1, an upper limit may be set to the value of the output voltage control setting signal Ecr. During the corrected second period T2, a lower limit may be set to the value of the output voltage control setting signal Ecr.

The reference rate of change is set to about 50 to 70 A/ms. If this value is too small, the penetration depth becomes shallow when the inductance value Lc is large, so that the required value cannot be reached. If this value is too large, the output voltage control setting signal Ecr is corrected to a part that does not require correction, and thus the welding state may become unstable.

Next, a numerical example will be given. This is a numerical example in the case of welding at an average welding current of 250 A and an average welding voltage of 21 V using a self-shielding flux-containing wire (material: steel, diameter: 1.6 mm) for the welding wire. Er=21V, Eur=10V, Edr=10V, Δu=2V, Δd=2V, T1r=2ms, T2r=4ms, T3r=6ms, and reference rate of change=65A/ms. As a result, one cycle becomes 12 ms, Vw1=31V, Vw2=11V, Vw3=21V, Iw1=400A, Iw2=60A, and Iw3=250A.

The rate of change of the welding current Iw in the period before the time t4 is 100 A/ms during the first period T1, 113 A/ms during the second period T2, and during the third period T3 It becomes 126A/ms. The rate of change of the welding current Iw in the period after time t7 is 75 A/ms during the first period T1, 85 A/ms during the second period T2, and during the third period T3 It becomes 95A/ms.

Next, the effects of the present embodiment will be described. First, the effect of the case where the inductance value Lc of the welding cable before time t4 is small is demonstrated. During the first period (T1) of the times t1 to t2, the welding current (Iw) becomes the largest value, the first welding current value (Iw1), so a large arc pressure acts on the melting sheet, and the melting sheet is concave directly under the wire. It becomes a concave shape, and the molten metal immediately under the wire becomes thin. During the second period (T2) of the times t2 to t3, the welding current (Iw) becomes the second welding current value (Iw2), which is the smallest value, so the arc shape becomes a constricted shape, and the arc becomes the molten metal directly under the wire. It is concentrated on this thin part. During the third period T3 of the times t3 to t4, the welding current Iw becomes the third welding current value Iw3, which is an intermediate value close to the welding current value determined by the feeding speed of the welding wire. By maintaining the third welding current value (Iw3) at an approximately constant value, the portion where the melted paper is concave is heated by the arc in the first half of the third period (T3), and the arc pressure is constant in the second half, so that the melted paper is concave. The damaged part disappears and becomes a calm state. At the time of transition to the first period (T1), if the molten paper does not become in a calm state, during the first period (T1), immediately under the wire does not become a concave shape, but a crushed shape, and the effect of deepening penetration is effective. Will be lost. Therefore, in order to reliably bring the molten ground into a calm state at the end of the third period T3, it is recommended that the third period T3 is set to a period longer than the first period T1 and the second period T2. desirable. Due to these effects, a deep penetration shape can be stably formed.

The first welding voltage value Vw1 (voltage increase value setting signal Eur) and the first period T1 (the first welding current value Iw1) so that the molten paper can be deformed into a concave concave shape. 1 A period setting signal T1r is set In addition, the second welding voltage value Vw2 (voltage decreases) so that the arc is constricted in a concave shape by the second welding current value Iw2 and concentrated directly under the wire. A value setting signal (Edr)) and a second period (T2) (a second period setting signal (T2r)) are set, and after heating the concave portion by focusing on the third welding current value (Iw3). A third welding voltage value Vw3 (voltage setting signal Er) and a third period T3 (third period setting signal T3r) are set so that the molten paper is in a calm state. The reason why the constant current control is not so as to be the first welding current value Iw1 to the third welding current value Iw3 is because it is necessary to control the constant voltage in order to keep the arc length at an appropriate value. Iw) is set, therefore, the first welding current value Iw1 to the third welding current value Iw3 slightly fluctuate depending on the state of the arc load.

Since the inductance value Lc of the welding cable increased from the time t4, the rate of change of the welding current Iw is gentle during the first period T1 of the times t4 to t5 and the second period T2 of the times t5 to t6. As it becomes, the amplitude becomes small. As a result, the maximum value of the welding current Iw during the first period T1 decreases, and the minimum value of the welding current Iw increases during the second period T2. For this reason, the effect of the above-described first period T1 and second period T2 is not sufficient. Such a state is determined by the rate of change of the welding current Iw being less than the reference rate of change.

When it is determined that the rate of change of the welding current Iw is less than the reference rate of change, the value of the output voltage control setting signal Ecr is increased by Δu during the first period T1 of the times t7 to t8, and During the second period T2, the value of the output voltage control setting signal Ecr is decreased by Δd. As a result, the rate of change of the welding current Iw becomes large, and it becomes substantially the same as the current waveform before the time t4. For this reason, the effect before time t4 mentioned above is exhibited.

In the present embodiment, when the rate of change of the welding current Iw is less than the reference rate of change, the increase in the output voltage control setting signal Ecr during the first period T1 (the increase in the first output voltage E1) and the second period Among (T2), the output voltage control setting signal Ecr is decreased (the second output voltage E2 is decreased). At this time, only one of them may be performed.

According to the first embodiment described above, during the first period, the first output voltage E1 is output to conduct the first welding current Iw1, and during the second period, the second output voltage E2 is output to perform the second welding. The current Iw2 is supplied, and during the third period, the third output voltage E3 is output to supply the third welding current Iw3, 0<E2<E3<E1, and 0<Iw2<Iw3<Iw1. , The first to third periods are repeated, and the rate of change of the welding current when each period of the first to third periods is switched is detected, and when the rate of change is less than a predetermined reference rate of change, the first output voltage E1 ) Increases and/or decreases the second output voltage E2. During the first period, a large arc pressure acts on the molten paper, and the molten paper becomes a concave shape in which the wire immediately underneath the wire becomes concave, and the molten metal immediately under the wire becomes thin. Subsequently, during the second period, the arc shape becomes constricted, and the arc is concentrated in a portion of the molten metal immediately under the wire in a thin state. Subsequently, during the third period, in the first half, the concave portion of the molten paper is concentrated and heated by the arc, and in the second half, since the arc pressure is constant, the concave portion of the molten paper disappears and becomes a calm state. In the present embodiment, by repeating these first to third periods, penetration can be deepened and high quality can be achieved in spray transfer welding. At this time, in this embodiment, since the inductance value of the welding cable is large, when the rate of change of the welding current is small and becomes less than the reference rate of change, the first output voltage value E1 increases and/or the second output voltage ( By reducing E2), the rate of change of the welding current can be increased. For this reason, it is not affected by the inductance value of the welding cable, and the above effect can be exhibited.

Further, according to the present embodiment, an alarm is issued when the rate of change of the welding current at the time of switching each period of the first to third period is less than the reference rate of change. When this alarm is not released and continues, it indicates that the rate of change of the welding current is less than the reference rate of change even by the correction of the output voltage. The welding operator can recognize that a case in which the penetration depth does not reach the required value occurs in such a state. For this reason, the welding operator can take measures to improve the installation environment of the welding apparatus so that the inductance value of the welding cable may be reduced.

[Embodiment 2]

In the invention of the second embodiment, when the rate of change of the welding current is less than the reference rate of change, the first period and/or the second period are lengthened.

3 is a block diagram of a welding power source for performing the arc welding method according to the second embodiment of the present invention. This drawing corresponds to FIG. 1 described above, and the same blocks are denoted by the same reference numerals, and their descriptions are not repeated. In this drawing, the output voltage control setting circuit ECR of FIG. 1 is replaced with the second output voltage control setting circuit ECR2. Hereinafter, this block will be described with reference to this drawing.

The second output voltage control setting circuit ECR2 includes an output voltage setting signal Er, a voltage increase value setting signal Eur, a voltage decrease value setting signal Edr, a first period setting signal T1r, and a second period. The following processing is performed by inputting the setting signal T2r, the third period setting signal T3r, and the change rate determination signal Sd, and outputting the output voltage control setting signal Ecr and the period signal Sp.

1) During the first period T1 determined by the first period setting signal T1r from the start of the first period, Ecr=Er+Eur is output, and the first period in the first period The output voltage control set value Ecr(1,1) of the period T1 and the first period set value T1r(1) are stored. Also, during this period, Sp=1 is output.

2) Subsequently, during the second period T2 determined by the second period setting signal T2r, Ecr = Er-Edr is output, and the second period T2 in the first period is output. It is stored as the voltage control set value Ecr(1,2) and the second period set value T2r(1). Also, during this period, Sp=2 is output.

3) Subsequently, during the third period T3 determined by the third period setting signal T3r, Ecr=Er is output. Also, during this period, Sp=3 is output.

4) During the first period T1 determined by the first period set value T1r(n-1) in the n-1th period from the start of the nth period, the nth first When the rate of change determination signal Sd at the start of the period T1 is at a low level, Ecr=Ecr(n-1,1) is output, and T1r(n)=T1r(n-1) is set, and when it is at a high level Ecr=Ecr(n-1,1)+Δu is output, and T1r(n)=T1r(n-1)+Δt. Then, the output voltage control set value Ecr(n,1) and the first period set value T1r(n) in the first period T1 in the nth cycle are stored. Δu and Δt are correction amounts, and are values of a predetermined amount. Also, during this period, Sp=1 is output.

5) Subsequently, during the second period T2 determined by the second period set value T2r(n-1) in the n-1th period, the start time of the nth first period T1 When the rate of change determination signal (Sd) of is low level, Ecr=Ecr(n-1,2) is output, and T2r(n)=T2r(n-1) is set, and at high level, Ecr=Ecr(n- 1,2)-Δd is output, and T2r(n) = T2r(n-1) + Δt. Then, the output voltage control set values Ecr(n,2) and T2r(n) in the second period T2 in the nth cycle are stored. Δd is a correction amount, and is a value of a predetermined amount. Also, during this period, Sp=2 is output.

6) Subsequently, during the third period T3 determined by the third period setting signal T3r, Ecr=Er is output regardless of the change rate determination signal Sd. Also, during this period, Sp=3 is output.

7) Repeat the treatments 4) to 6) above.

In the second output voltage control setting circuit ECR2, the operation of the output voltage control setting signal Ecr is the same as that of the output voltage control setting circuit ECR of FIG. 1. On the other hand, in the second output voltage control setting circuit ECR2, the first period T1 when the rate of change determination signal Sd is at a high level is increased by Δt from the value of the previous period, and the second period T2 Is lengthened by Δt from the value of the previous period, and the third period T3 does not change. This operation is different from the output voltage control setting circuit ECR of FIG. 1.

Fig. 4 is a timing chart of each signal in the welding power supply of Fig. 3 showing the arc welding method according to the second embodiment of the present invention. (A) of this figure shows the time change of the output voltage control setting signal (Ecr), (B) of this figure shows the time change of the welding voltage (Vw), and (C) of this figure shows the time of the welding current (Iw) The change is shown, and (D) of this figure shows the time change of the change rate discrimination signal Sd. In the description of this figure, differences from the operation of Fig. 2 described above will be described, and the description of the same operation will not be repeated. Hereinafter, it demonstrates with reference to this drawing.

In this figure, since the operation in the period up to time t7 is the same as that of FIG. 2, the description is not repeated.

As shown in FIG. (D), the rate of change determination signal Sd at the start time t7 of the first period T1 is at a high level. Therefore, as shown in (A) of this figure, the output voltage control setting signal Ecr becomes a value corrected from the value of the previous period, and during the first period T1 of the times t7 to t8, Er+Eur+ It becomes the value obtained by adding Δu to the value of Δu and the previous period, and becomes the value obtained by subtracting Δd from the value of Er-Edr-Δd and the previous period during the second period (T2) of the times t8 to t9, and the times t9 to t10 During the third period (T3) of, the value of Er and the previous period remains as it is. Similarly, as shown in this figure, the first period T1 becomes a value corrected from the value of the previous period, and Δt is the first period T1 = T1r+Δt and the value of the previous period at times t7 to t8. Is a value obtained by adding Δt from the value of the second period (T2) = T2r+Δt and the previous period at times t8 to t9, and the third period (T3) at times t9 to t10 is T3r and The value of the previous cycle remains as it is.

As shown in (B) of this figure, during the first period T1 of the times t7 to t8, the welding voltage Vw increases from the third welding voltage value Vw3 to the same slope as in FIG. 2, and the first period Since (T1) is getting longer, it becomes approximately the first welding voltage value Vw1 of a constant value. During the second period T2 of the times t8 to t9, the welding voltage Vw decreases from the first welding voltage value Vw1 to the same slope as in FIG. It becomes the second welding voltage value Vw2. During the third period T3 of the times t9 to t10, the welding voltage Vw increases from the second welding voltage value Vw2 to the same slope as in FIG. 2 to become a third welding voltage value Vw3 having an approximately constant value.

Similarly, as shown in (C) of this figure, during the first period T1 of the times t7 to t8, the welding current Iw increases from the third welding current value Iw3 to the same slope as in FIG. Since one period T1 is getting longer, it becomes approximately the first welding current value Iw1 of a constant value. During the second period T2 of the times t8 to t9, the welding current Iw decreases from the first welding current value Iw1 to the same slope as in FIG. It becomes the 2nd welding current value Iw2. During the third period T3 of the times t9 to t10, the welding current Iw increases from the second welding current value Iw2 to the same slope as in FIG. 2 to become a third welding current value Iw3 having an approximately constant value. Accordingly, the amplitude of the welding current Iw in the first period T1 and the second period t2 becomes substantially the same value as before the time t4. In addition, since the welding current Iw of the first period T1 and the second period T2 is changed differently from the case of FIG. 2 and there is a portion of a certain value, even if the inductance value Lc of the welding cable becomes larger The amplitude before time t4 can be obtained.

As shown in FIG. (D), the rate of change determination signal Sd at the start time t10 of the first period T1 is at a low level. Therefore, as shown in this figure, the first period T1 becomes the same value as the value of the previous period, the first period T1 at the times t10 to t11 = T1r+Δt, and the times t11 to t12 The second period (T2) = T2r + ?t, and the third period (T3) = T3r at times t12 to t13. For this reason, the waveforms of the welding voltage Vw and the welding current Iw become the same as in the previous period.

After this, the operation of the cycle of the times t10 to t13 is repeated. The above-described correction amount Δt is set to about 0.1 to 1.0 ms. If this value is too large, the welding condition becomes unstable, and if it is too small, it takes time to correct, and the welding quality deteriorates during the correction period. An upper limit may be set in the corrected first period T1 and second period T2.

In this embodiment, when the rate of change of the welding current Iw is less than the reference rate of change, the first period T1 and the second period T2 are lengthened. At this time, only one of them may be lengthened.

According to the second embodiment described above, when the rate of change of the welding current at the time of switching each period of the first period to the third period is less than the reference rate of change, the first period and/or the second period are lengthened. Accordingly, in this embodiment, in addition to the effect of the first embodiment, even if the inductance value of the welding cable becomes larger, the amplitude of the welding current can be maintained at a desired value during the first and second periods, thereby ensuring deep penetration. can do.

1: welding wire
2: base material
3: arc
4: welding torch
5: feed roll
6, 7: welding cable
AR: alarm circuit
E: output voltage
E1: first output voltage
E2: second output voltage
E3: 3rd output voltage
ECR: Output voltage control setting circuit
Ecr: Output voltage control setting signal
ECR2: 2nd output voltage control setting circuit
ED: output voltage detection circuit
Ed: output voltage detection signal
EDR: Voltage reduction value setting circuit
Edr: Voltage reduction value setting signal
ER: Output voltage setting circuit
Er: Output voltage setting signal
EUR: Voltage increase value setting circuit
Eur: Voltage increase value setting signal
EV: Voltage error amplifier circuit
Ev: Voltage error amplification signal
ID: current detection circuit
Id: current detection signal
Iw: welding current
Iw1: first welding current
Iw2: second welding current
Iw3: 3rd welding current
Lc: Inductance value of welding cable
PM: Power main circuit
SD: Rate of change discrimination circuit
Sd: change rate discrimination signal
Sp: period signal
T1: 1st period
T1R: first period setting circuit
T1r: first period setting signal
T2: 2nd period
T2R: second period setting circuit
T2r: second period setting signal
T3: 3rd period
T3R: 3rd period setting circuit
T3r: 3rd period setting signal
Vw: welding voltage
Vw1: first welding voltage value
Vw2: second welding voltage value
Vw3: third welding voltage value
WL: Reactor
Δd, Δt, Δu: correction amount

Claims (3)

In the arc welding method of supplying a welding wire, outputting an output voltage from a welding power source, energizing a welding current, and welding according to a spray transition form,
During the first period, the first output voltage E1 is output to conduct the first welding current Iw1, and during the second period, the second output voltage E2 is output to conduct the second welding current Iw2, During the third period, the third output voltage E3 is output to conduct the third welding current Iw3, 0<E2<E3<E1, 0<Iw2<Iw3<Iw1, and the first to the first period. Repeat 3 periods,
Detects a rate of change of the welding current when switching each period of the first period to the third period, and when the rate of change is less than a predetermined reference rate of change, the first output voltage E1 increases and/or the second 2 Reduce the output voltage E2,
When the rate of change is less than the reference rate of change, an alarm is issued. delete In the arc welding method of supplying a welding wire, outputting an output voltage from a welding power source, energizing a welding current, and welding according to a spray transition form,
During the first period, the first output voltage E1 is output to conduct the first welding current Iw1, and during the second period, the second output voltage E2 is output to conduct the second welding current Iw2, During the third period, the third output voltage E3 is output to conduct the third welding current Iw3, 0<E2<E3<E1, 0<Iw2<Iw3<Iw1, and the first to the first period. Repeat 3 periods,
Detects a rate of change of the welding current when switching each period of the first period to the third period, and when the rate of change is less than a predetermined reference rate of change, the first output voltage E1 increases and/or the second 2 Reduce the output voltage E2,
When the rate of change is less than the reference rate of change, the first period and/or the second period are lengthened.

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