Submerged arc welding control method

Abstract

To provide a submerged arc welding method, in which even when short-circuit occurs between a welding wire and a base material, a welding quality can be maintained excellently.SOLUTION: In a submerged arc welding method, in which a welding wire is fed and welding voltages Vw and welding currents Iw are outputted between the welding wire and a base material to generate arc so as to weld the wire to the material, when it is determined that short-circuit has occurred between the welding wire and the base material at a time t4, short-circuit currents Iw are carried, a peak value of the short-circuit currents Iw is controlled to 1500 A or more and 2500 A or less, and a rise rate of the short-circuit currents Iw is controlled to 400 A / ms or more and 1500 A / ms or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control for releasing a short circuit in submerged arc welding. [Background technology]

[0002] A submerged arc welding method has been disclosed in which the arc length can be controlled by variable feed speed control that changes the feed speed of the welding wire in accordance with the welding voltage (see, for example, Patent Document 1).

[0003] In variable feed speed control, the welding voltage, which correlates with the arc length, is maintained at an appropriate value by feedback-controlling the feed speed based on the error between the detected value and the set value of the welding voltage. In submerged arc welding using a large-diameter wire, the wire melting rate is unlikely to change even when the welding current changes, making it difficult to achieve the self-regulation of the arc length that is commonly used in consumable electrode arc welding using a welding power source with constant voltage characteristics. For this reason, in submerged arc welding, the arc length is maintained at an appropriate value by performing variable feed speed control using a welding power source with constant current characteristics. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-271944 Summary of the Invention [Problem to be solved by the invention]

[0005] Submerged arc welding is a welding method that is basically performed under welding conditions that do not cause short circuits. Therefore, if a short circuit occurs between the welding wire and the base material (molten pool) due to fluctuations in the welding state in submerged arc welding, it can cause welding defects, uneven penetration, and other problems, resulting in poor weld quality.

[0006] Therefore, an object of the present invention is to provide a submerged arc welding control method that can maintain good welding quality even if a short circuit occurs between the welding wire and the base metal. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the invention of claim 1 is as follows: 1. A submerged arc welding control method for feeding a welding wire and outputting a welding voltage and a welding current between the welding wire and a base metal to generate an arc for welding, comprising: When a short circuit between the welding wire and the base material is detected, a short circuit current is applied; The peak value of the short-circuit current is controlled to 1500 A or more and 2500 A or less. The present invention relates to a method for controlling submerged arc welding.

[0008] The invention of claim 2 is as follows: The rate of rise of the short-circuit current is controlled to be 400 A / ms or more and 1500 A / ms or less. 2. The method for controlling submerged arc welding according to claim 1, wherein:

[0009] The invention of claim 3 is as follows: outputting the AC welding voltage and the AC welding current by periodically switching the output polarity between electrode positive polarity and electrode negative polarity; Control is performed so that the output polarity is not switched during the short circuit. 3. The method for controlling submerged arc welding according to claim 1 or 2.

[0010] The invention of claim 4 is as follows: After the short circuit is released and the arc is re-strike, the absolute value of the welding current is reduced to a polarity switching current value to switch the output polarity. 4. The method for controlling submerged arc welding according to claim 3. [Effects of the Invention]

[0011] According to the submerged arc welding control method of the present invention, good welding quality can be maintained even if a short circuit occurs between the welding wire and the base metal. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram of a welding device for carrying out a submerged arc welding control method according to an embodiment of the present invention. [Figure 2] 2 is a timing chart of each signal in the welding device of FIG. 1 when a welding current having a sine waveform is applied in an AC output mode. [Figure 3] 2 is a timing chart of each signal in the welding device of FIG. 1 in a DC output mode. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] 1 is a block diagram of a welding device for carrying out a submerged arc welding control method according to an embodiment of the present invention. Each block will be described below with reference to the diagram.

[0015] The power supply main circuit PM is connected to a commercial power supply (not shown) such as a three-phase 200V power supply, and receives as input a current error amplification signal Ei (described later) and a polarity switching signal Spn (described later), performs inverter control in accordance with the current error amplification signal Ei, switches between electrode positive polarity EP and electrode negative polarity EN in accordance with the polarity switching signal Spn, and outputs an AC or DC welding current Iw and welding voltage Vw. Although not shown, this power supply main circuit PM includes a primary rectifier that rectifies the commercial power supply, a smoothing capacitor that smooths the rectified DC, a primary-side inverter circuit that converts the smoothed DC into high-frequency AC, a high-frequency transformer that steps down the high-frequency AC to a voltage value suitable for welding, a secondary rectifier that rectifies the stepped-down high-frequency AC to DC, a reactor that smooths the rectified DC, a secondary-side inverter circuit that switches the smoothed DC between electrode positive polarity EP and electrode negative polarity EN in accordance with a polarity switching signal Spn, a modulation circuit that receives as input the current error amplified signal Ei and outputs a pulse-width modulated signal, and a drive circuit that receives as input the pulse-width modulated signal to drive the switching elements of the primary-side inverter circuit.

[0016] The welding wire 1 is fed through the welding torch 4 by the rotation of a feed roll 5 connected to a feeder WM, and an arc 3 is generated between the welding wire 1 and the base material 2. A welding voltage Vw is applied between the power feed tip (not shown) of the welding torch 4 and the base material 2, and a welding current Iw flows. A flux feeder 6 is provided in the welding device, which supplies flux (not shown) to the arc generation area. The arc generation area is covered by the flux, so the arc 3 cannot be seen from outside. The welding torch 4 is mounted on an automatic cart, welding robot, or the like and moves along the weld line.

[0017] The output mode setting circuit MR is a switch or the like provided on the front panel of the welding power source, and outputs an output mode setting signal Mr that goes to a high level when the welding operator selects the AC output mode and goes to a low level when the welding operator selects the DC output mode.

[0018] The voltage detection circuit VD detects the instantaneous value of the welding voltage Vw, converts it into an absolute value, and outputs a voltage detection signal Vd.

[0019] The voltage effective value detection circuit VED receives the voltage detection signal Vd, calculates an effective value from the voltage detection signal Vd, and outputs an effective voltage detection signal Ved.

[0020] The external characteristic control circuit CC receives the output mode setting signal Mr, the voltage effective value detection signal Ved, and the voltage detection signal Vd as inputs, and outputs the current effective value setting signal Ier and the DC current setting signal Idr calculated based on the following equation (1) or (2): 1) When the output mode setting signal Mr is at High level (AC output mode) The external characteristics are the output characteristics of the welding power source, and can be expressed as a function Ve = f(Ie), where the effective value of the welding current Ie is the input and the effective value Ve of the welding voltage Vw is the output. If the function is defined as a straight line, it becomes the following equation. Ve=K·Ie+V0 Here, K [V / A] is the slope of a predetermined line, and V0 is the predetermined value of Ve when Ie = 0. Rearranging the above equation with Ie, substituting Ie with the current effective value setting signal Ier and Ve with the voltage effective value detection signal Ved, yields the following equation. Ier=(Ved-V0) / K (1) In AC output mode, the external characteristics are controlled by this formula. K is set in the range of approximately -0.1 to -40V / 100A, and V0 is set in the range of approximately 20 to 50V. 2) When the output mode setting signal Mr is at low level (DC output mode) In the above (1), if Ier is replaced with Idr and Ved with Vd, the following equation is obtained: Idr=(Vd-V0) / K (2) formula In DC output mode, the external characteristics are controlled by this formula.

[0021] The current detection circuit ID detects the instantaneous value of the welding current Iw, converts it into an absolute value, and outputs a current detection signal Id.

[0022] The current effective value detection circuit IED receives the current detection signal Id, calculates an effective value from the current detection signal Id, and outputs a current effective value detection signal Ied.

[0023] The current amplitude modulation circuit AMC receives the RMS current detection signal Ied and the RMS current setting signal Ier, performs modulation control based on the error amplification value of both signals, and outputs a current amplitude modulation signal Amc. This circuit changes the amplitude of the welding current Iw so that the RMS value of the welding current Iw becomes equal to the set value.

[0024] The electrode positive polarity period setting circuit TPR outputs a predetermined electrode positive polarity period setting signal Tpr, and the electrode negative polarity period setting circuit TNR outputs a predetermined electrode negative polarity period setting signal Tnr.

[0025] The short-circuit determination circuit SD receives the voltage detection signal Vd. If the voltage detection signal Vd is less than a predetermined short-circuit determination value, the circuit determines that the welding wire 1 and the base material 2 are short-circuited and outputs a high-level short-circuit determination signal Sd. If the voltage detection signal Vd is greater than or equal to a predetermined short-circuit determination value, the circuit determines that an arc is being generated and outputs a low-level short-circuit determination signal Sd. In submerged arc welding, a welding voltage of at least approximately 20 V is required to maintain an arc, regardless of the diameter of the welding wire. Therefore, the short-circuit determination value must be 20 V or less, and more preferably between 10 V and 18 V. If the short-circuit determination value exceeds 18 V, a momentary change in the welding voltage is likely to be mistakenly determined as a short circuit. Furthermore, in submerged arc welding, the output terminal of the welding power source and the welding torch may be connected by a long welding cable of several tens of meters. In this case, if the welding voltage is detected at the output terminal, the voltage drop due to the welding cable will be added to the actual welding voltage. Therefore, if the short-circuit determination value becomes too small, it becomes difficult to determine a short circuit. For this reason, the short-circuit determination value is preferably 10 V or more.

[0026] The current setting circuit IR receives the electrode positive polarity period setting signal Tpr, the electrode negative polarity period setting signal Tnr, the current amplitude modulation signal Amc, and the short circuit determination signal Sd as inputs, performs the following processes 1) to 5), and outputs a current setting signal Ir having a half-cycle waveform of a sine wave or a square wave, as well as a polarity signal Tpn. 1) During the electrode positive polarity period Tep set by the electrode positive polarity period setting signal Tpr, the start and end points of the period are polarity switching current values, and a half-cycle sine wave waveform with an amplitude set by the current amplitude modulation signal Amc is output as the current setting signal Ir. During the electrode positive polarity period Tep, a polarity signal Tpn that is at a high level is output. 2) During the electrode negative polarity period Ten set by the electrode negative polarity period setting signal Tnr, the start and end points of the period are the polarity switching current values, and a half-cycle sine wave waveform with an amplitude set by the current amplitude modulation signal Amc is output as the current setting signal Ir. During the electrode negative polarity period Ten, a polarity signal Tpn that is at a low level is output. 3) When the short circuit determination signal Sd is at a low level (arc period), the above steps 1) and 2) are repeated. 4) When the short-circuit determination signal Sd is at a high level (short-circuit period) and the polarity signal Tpn is at a high level (electrode positive polarity EP), only the above 1) is repeated. 5) When the short-circuit determination signal Sd is at a high level (short-circuit period) and the polarity signal Tpn is at a low level (electrode negative polarity EN), only the above 2) is repeated.

[0027] The polarity switching setting circuit SPN receives the output mode setting signal Mr, the short circuit determination signal Sd, and the polarity signal Tpn as inputs, performs the following processing, and outputs the polarity switching signal Spn. 1) When the output mode setting signal Mr is at a high level (AC output mode), the short circuit determination signal Sd is at a low level (arc period), and the polarity signal Tpn is at a high level (electrode positive polarity EP), a high-level polarity switching signal Spn is output. 2) When the output mode setting signal Mr is at a high level (AC output mode), the short circuit determination signal Sd is at a low level (arc period), and the polarity signal Tpn is at a low level (electrode negative polarity EN), a low-level polarity switching signal Spn is output. 3) When the output mode setting signal Mr is at a high level (AC output mode) and the short circuit determination signal Sd changes to a high level (short circuit period), the polarity switching signal Spn is maintained at its current value and output, thereby preventing polarity switching during the short circuit period. 4) When the output mode setting signal Mr is at a low level (DC output mode), a polarity switching signal Spn is output at a high level when the electrode positive polarity EP is set, and at a low level when the electrode negative polarity EN is set.

[0028] The short-circuit current peak value setting circuit IPR outputs a predetermined short-circuit current peak value setting signal Ipr, which is preferably set to a value between 1500 A and 2500 A, more preferably between 1800 A and 2200 A.

[0029] The short-circuit current rise rate setting circuit SR outputs a predetermined short-circuit current rise rate setting signal Sr, which is preferably set to a value between 400 A / ms and 1500 A / ms, and more preferably between 600 A / ms and 1200 A / ms.

[0030] The short-circuit current setting circuit ISR receives as input the current setting signal Ir, the short-circuit determination signal Sd, the short-circuit current peak value setting signal Ipr, and the short-circuit current rise rate setting signal Sr. When the short-circuit determination signal Sd changes to a high level (short circuit), the short-circuit current setting circuit ISR outputs a short-circuit current setting signal Isr which rises from the value of the current setting signal Ir at the rate set by the short-circuit current rise rate setting signal Sr, and which maintains the value of the short-circuit current peak value setting signal Ipr.

[0031] The current control setting circuit ICR receives the output mode setting signal Mr, the short circuit determination signal Sd, the current setting signal Ir, the DC current setting signal Idr, and the short circuit current setting signal Isr as inputs, performs the following processing 1) or 2), and outputs the current control setting signal Icr. 1) When the output mode setting signal Mr is at High level (AC output mode) When the short circuit determination signal Sd is at a low level (arc period), the current setting signal Ir is output as the current control setting signal Icr, and when the short circuit determination signal Sd is at a high level (short circuit period), the short circuit current setting signal Isr is output as the current control setting signal Icr. 2) When the output mode setting signal Mr is at low level (DC output mode) When the short circuit determination signal Sd is at a low level (arc period), the DC current setting signal Idr is output as the current control setting signal Icr, and when the short circuit determination signal Sd is at a high level (short circuit period), the short circuit current setting signal Isr is output as the current control setting signal Icr.

[0032] The current error amplifier circuit EI receives the current control setting signal Icr and the current detection signal Id, amplifies the difference between the two values, and outputs a current error amplified signal Ei. This circuit controls the welding device to a constant current.

[0033] The voltage setting circuit VR outputs a predetermined voltage setting signal Vr.

[0034] The variable feed speed control circuit FMC receives the RMS voltage detection signal Ved and the voltage setting signal Vr as inputs, performs variable feed speed control using P (proportional) control, PI (proportional-integral) control, or PID (proportional-integral-derivative) control based on the error amplification value of these two values, and outputs a feed speed modulation signal Fmc. This circuit variably controls the feed speed Fw so that the arc length is maintained at an appropriate value. In DC output mode, the voltage detection signal Vd may be used instead of the RMS voltage detection signal Ved.

[0035] The feed control circuit FC receives the feed speed modulation signal Fmc as an input and outputs a feed control signal Fc to the feeder WM to control the feed speed Fw of the welding wire 1 to a speed determined by the feed speed modulation signal Fmc.

[0036] Figure 2 is a timing chart of each signal in the welding device of Figure 1 when a sinusoidal welding current is applied in AC output mode. Figure 2(A) shows the change over time in welding current Iw, Figure 2(B) shows the change over time in welding voltage Vw, Figure 2(C) shows the change over time in short circuit detection signal Sd, and Figure 2(D) shows the change over time in polarity switching signal Spn. The operation of each signal will be explained below with reference to the figure.

[0037] In the figure, positive values ​​above 0 A and 0 V indicate positive electrode polarity EP, and negative values ​​below 0 A and 0 V indicate negative electrode polarity EN.

[0038] During the period from time t1 to t2, as shown in FIG. 1D, the polarity switching signal Spn is at a high level, resulting in electrode positive polarity EP. As shown in FIG. 1A, during the electrode positive polarity period Tep from time t1 to t2, the welding current Iw has a positive polarity switching current value at the start point t1 and end point t2 of the period, and exhibits a positive half-cycle waveform of a sine wave with an amplitude set by the current amplitude modulation signal Amc. During the period from time t2 to t3, as shown in FIG. 1D, the polarity switching signal Spn is at a low level, resulting in electrode negative polarity EN. As shown in FIG. 1A, during the electrode negative polarity period Ten from time t2 to t3, the welding current Iw has a negative polarity switching current value at the start point t2 and end point t3 of the period, and exhibits a negative half-cycle waveform of a sine wave with an amplitude set by the current amplitude modulation signal Amc. The electrode positive polarity period Tep is set by the electrode positive polarity period setting signal Tpr in FIG. 1. The electrode negative polarity period Ten is set by the electrode negative polarity period setting signal Tnr in Figure 1. The current effective value setting signal Ier in Figure 1 is calculated by inputting the voltage effective value detection signal Ved into the above equation (1). The welding current amplitude is modulated and controlled so that the current effective value detection signal Ied in Figure 1 is equal to the current effective value setting signal Ier. This allows external characteristic control. For example, Tep = 10 ms, Ten = 10 ms, polarity switching current value = ±200 A, and amplitude ±1000 A.

[0039] As shown in Figure 1(B), the welding voltage Vw has a waveform similar to a square wave. The effective value of the welding voltage Vw is a value correlated with the arc length. The feed speed Fw in Figure 1 is variably controlled so that the voltage effective value detection signal Ved is equal to the voltage setting signal Vr in Figure 1. This allows arc length control.

[0040] From time t3, as shown in (D) of the figure, the polarity switching signal Spn again becomes high level (electrode positive polarity EP), and the above operation is repeated. When the welding wire and base metal are short-circuited at time t4 during this electrode positive polarity EP, the welding voltage Vw suddenly decreases to a short-circuit voltage value of several volts, as shown in (B) of the figure, and the short-circuit determination signal Sd changes to high level, as shown in (C) of the figure. In response to this, as shown in (A) of the figure, the welding current Iw is controlled to the value of the short-circuit current setting signal Isr of FIG. 1. From time t4, the welding current Iw increases at a rate set by the short-circuit current increase rate setting signal Sr of FIG. 1, and when it reaches a peak value set by the short-circuit current peak value setting signal Ipr of FIG. 1, it maintains that value until the short circuit is released at time t5. During the short-circuit period from time t4 to t5, as shown in (D) of the figure, the polarity switching signal Spn remains high level, and no polarity switching occurs. At time t5, when the short circuit is released and the arc is re-struck, as shown in FIG. 1B, the welding voltage Vw rises sharply to an arc voltage value of several tens of volts, and the short circuit determination signal Sd changes to low level as shown in FIG. 1C. In response to this, as shown in FIG. 1A, the welding current Iw decreases from time t5 and returns to the half-cycle sinusoidal waveform observed during the arc period. Then, at time t6, the welding current Iw reaches the polarity switching current value, and as shown in FIG. 1D, the polarity switching signal Spn changes to low level and the electrode polarity becomes negative EN. From this point on, the operation from time t2 to t3 is repeated. The short circuit period from time t4 to t5 is, for example, approximately 200 ms. The electrode positive polarity EP and electrode negative polarity EN are approximately 10 ms, and in this case, the short circuit period is 10 times longer.

[0041] Figure 3 is a timing chart of each signal in the welding device of Figure 1 when in DC output mode. Figure 3(A) shows the change over time in welding current Iw, Figure 3(B) shows the change over time in welding voltage Vw, Figure 3(C) shows the change over time in short circuit detection signal Sd, and Figure 3(D) shows the change over time in polarity switching signal Spn. The operation of each signal will be explained below with reference to this figure.

[0042] Since the DC output mode and electrode positive polarity EP are selected, the polarity switching signal Spn remains high throughout the entire period, resulting in a positive electrode polarity EP, as shown in (D) of the figure. The arc period occurs from time t1 to t2, and the short-circuit detection signal Sd remains low, as shown in (C) of the figure. As shown in (A) of the figure, the welding current Iw assumes a DC waveform and is controlled to the value of the DC current setting signal Idr in Figure 1. The DC current setting signal Idr is calculated by inputting the voltage detection signal Vd into equation (2) above. This allows external characteristic control to be performed. As shown in (B) of the figure, the welding voltage Vw assumes a DC waveform and assumes a value correlated with the arc length. The feed speed Fw in Figure 1 is variably controlled so that the voltage detection signal Vd is equal to the voltage setting signal Vr in Figure 1. This allows arc length control to be performed.

[0043] At time t2, when a short circuit occurs between the welding wire and the base metal, as shown in FIG. 1B, the welding voltage Vw suddenly decreases to a short-circuit voltage value of several volts, and as shown in FIG. 1C, the short-circuit determination signal Sd changes to a high level. In response to this, as shown in FIG. 1A, the welding current Iw is controlled to the value of the short-circuit current setting signal Isr in FIG. 1. From time t4, the welding current Iw increases at a rate set by the short-circuit current increase rate setting signal Sr in FIG. 1. When it reaches a peak value set by the short-circuit current peak value setting signal Ipr in FIG. 1, it maintains that value until the short circuit is released at time t3. At time t3, when the short circuit is released and the arc is re-struck, the welding voltage Vw suddenly increases to an arc voltage value of several tens of volts, as shown in FIG. 1B, and the short-circuit determination signal Sd changes to a low level, as shown in FIG. 1C. In response to this, as shown in FIG. 1A, the welding current Iw decreases from time t3 and returns to the DC waveform it had during the arc period.

[0044] The effects of this embodiment will be described below. According to this embodiment, when a short circuit between the welding wire and the base metal is detected, a short-circuit current is passed through, and the peak value of the short-circuit current is controlled to be 1500 A or more and 2500 A or less. Submerged arc welding is a welding method performed under welding conditions that basically prevent short circuits from occurring. Therefore, in submerged arc welding, if a short circuit occurs between the welding wire and the base metal (molten pool) due to fluctuations in the welding state, there is a problem that welding defects, uneven penetration, etc. occur, resulting in poor welding quality. This is because, in conventional technology, even if a short circuit occurs, no special control is performed to quickly release the short circuit and return to an arc-generating state, resulting in a short-circuit period lasting 500 ms or more. In contrast, in this embodiment, when a short circuit occurs, control is performed to pass a short-circuit current with a peak value of 1500 A or more and 2500 A or less. By passing a short-circuit current of a high current value, melting of the protruding portion of the welding wire is promoted and the short circuit is quickly released. As a result, in this embodiment, the short-circuit period can be shortened to approximately 200 ms or less, thereby preventing deterioration of welding quality. If the peak value of the short-circuit current is less than 1500 A, the effect of quickly releasing the short circuit will be insufficient, and if it exceeds 2500 A, the load on the welding equipment will be too heavy. It is more preferable to control the peak value of the short-circuit current to 1800 A or more and 2200 A or less.

[0045] More preferably, according to this embodiment, the rate of rise of the short-circuit current is controlled to be 400 A / ms or more and 1500 A / ms or less. If the rate of rise is less than 400 A / ms, the effect of quickly releasing the short circuit becomes insufficient. If the rate of rise exceeds 1500 A / ms, the welding state may become unstable. Therefore, by controlling the rate of rise within the above range, the short circuit can be quickly released without causing the welding state to become unstable. It is even more preferable to control the rate of rise to be 600 A / ms or more and 1200 A / ms or less.

[0046] More preferably, according to this embodiment, the output polarity is periodically switched between electrode positive polarity and electrode negative polarity to output AC welding voltage and welding current, and the output polarity is controlled not to be switched during a short circuit. If the output polarity were switched during a short circuit, the welding current would temporarily decrease to 0 A, making it impossible to quickly release the short circuit. For this reason, in this embodiment, the output polarity is controlled not to be switched during a short circuit, thereby quickly releasing the short circuit.

[0047] More preferably, according to this embodiment, after the short circuit is released and the arc is re-struck, the absolute value of the welding current is reduced to the polarity switching current value to switch the output polarity. This allows for smooth switching of the output polarity after the short circuit is released, thereby improving the arc generation condition. [Explanation of symbols]

[0048] 1 welding wire 2 Base material 3. Arc 4 welding torches 5 Feeding roll 6 Flux supply machine AMC Current Amplitude Modulation Circuit Amc Current Amplitude Modulation Signal CC External characteristics control circuit EI current error amplifier circuit Ei Current error amplification signal EN electrode negative polarity EP electrode positive polarity FC feed control circuit Fc feed control signal FMC variable speed feed control circuit Fmc Feed speed modulation signal Fw Feeding speed ICR current control setting circuit Icr Current control setting signal ID current detection circuit Id Current detection signal Idr DC current setting signal IED current effective value detection circuit Ied Current effective value detection signal IPR Short circuit current peak value setting circuit Ipr Short circuit current peak value setting signal IR current setting circuit Ir Current setting signal ISR short circuit current setting circuit Isr Short circuit current setting signal Iw Welding current MR output mode setting circuit Mr output mode setting signal PM power supply main circuit SD short circuit detection circuit Sd Short circuit detection signal SPN polarity switching setting circuit SPN polarity switching signal SR Short-circuit current rise rate setting circuit Sr Short circuit current rise rate setting signal Ten electrode negative polarity period Tep electrode positive polarity period TNR electrode negative polarity period setting circuit Tnr Electrode negative polarity period setting signal TPN polarity signal TPR electrode positive polarity period setting circuit Tpr electrode positive polarity period setting signal VD voltage detection circuit Vd Voltage detection signal VED voltage effective value detection circuit Ved Voltage effective value detection signal VR voltage setting circuit Vr voltage setting signal Vw welding voltage WM feeder

Claims

1. 1. A submerged arc welding control method for feeding a welding wire and outputting a welding voltage and a welding current between the welding wire and a base metal to generate an arc for welding, comprising: When a short circuit between the welding wire and the base material is detected, a short circuit current is applied; The peak value of the short-circuit current is controlled to be 1500 A or more and 2500 A or less. A method for controlling submerged arc welding.

2. The rate of rise of the short-circuit current is controlled to be 400 A / ms or more and 1500 A / ms or less.

2. The method for controlling submerged arc welding according to claim 1.

3. outputting the AC welding voltage and the AC welding current by periodically switching the output polarity between electrode positive polarity and electrode negative polarity; Control is performed so that the output polarity is not switched during the short circuit.

3. The method for controlling submerged arc welding according to claim 1 or 2.

4. After the short circuit is released and the arc is re-strike, the absolute value of the welding current is reduced to a polarity switching current value to switch the output polarity.

4. The method for controlling submerged arc welding according to claim 3.

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