JP2019093403A - Arc-welding method - Google Patents

Abstract

To provide an arc-welding method that performs welding by alternately switching pulse-arc welding and short-circuit transfer welding, in which welding methods can be smoothly switched.SOLUTION: In an arc-welding method in which welding is performed by alternately switching a period of time during which a welding voltage corresponding to a first welding voltage set value is outputted and a welding wire is fed at first feed speed to perform pulse arc-welding and a period of time during which a welding voltage corresponding to a second welding voltage set value is outputted and the welding wire is fed at second feed speed to perform short-circuit transfer welding, the period of time for the pulse arc-welding is constituted of a commencement transition period at times t4-t5, a stationary pulse period at times t1-t2 and a termination transition period at times t2-t3. The welding methods are switched by changing the feed speed from the second feed speed to the first feed speed with slope in the commencement transition period, and by changing the speed from the first feed speed to the second feed speed with slope in the termination transition period.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an arc welding method in which welding is performed by alternately switching a period in which pulse arc welding is performed and a period in which short circuit transition welding is performed.

  A method is used in which a welding wire is fed, and a period in which pulse arc welding is performed and a period in which short circuit transfer welding is performed are alternately switched and welding (see, for example, Patent Document 1). The switching frequency in this case is about 0.1 to 10 Hz. In this welding method, a scale-like beautiful bead can be formed. Furthermore, in this welding method, the heat input to the base material can be controlled by adjusting the ratio between the period of pulse arc welding and the period of short circuit transfer welding.

JP 2005-313179 A

  In the prior art, there is a problem that spattering occurs and the welding state becomes unstable because the droplet transfer form changes when switching between pulse arc welding and short circuit transfer welding.

  Therefore, it is an object of the present invention to provide an arc welding method capable of smoothly switching between pulse arc welding and short circuit transition welding.

In order to solve the problems described above, the invention of claim 1 is
The welding voltage corresponding to the first welding voltage setting value is output, the welding wire is fed at the first feeding speed, and the period when pulse arc welding is performed, and the welding voltage corresponding to the second welding voltage setting value is output. In the arc welding method, in which the wire is fed at a second feed speed and the period during which short circuit transition welding is performed is alternately switched and welding is performed,
The period of the pulse arc welding is formed of an initial transition period, a steady pulse period and a final transition period,
Changing from the second feeding speed to the first feeding speed with a slope during the initial transition period,
Changing from the first feeding speed to the second feeding speed with a slope during the final transition period,
It is an arc welding method characterized by the above.

The invention according to claim 2 changes the second welding voltage setting value to the first welding voltage setting value with a slope during the initial transition period,
In the final transition period, the first welding voltage set value is changed from the first welding voltage set value to the second welding voltage set value with a slope.
It is an arc welding method of Claim 1 characterized by the above-mentioned.

The invention of claim 3 is characterized in that the rate of change of the delivery speed during the initial transition period is smaller than the rate of change of the delivery speed during the final transition period.
It is an arc-welding method of Claim 1 or 2 characterized by the above-mentioned.

The invention of claim 4 is the arc welding method according to any one of claims 1 to 3, wherein the initial transition period and the final transition period include a plurality of pulse periods.

  According to the present invention, switching between pulse arc welding and short circuit transition welding can be smoothly performed.

It is a block diagram of a welding power supply for enforcing the arc welding method concerning Embodiment 1 of the present invention. It is a timing chart of each signal in the welding power supply of FIG. 1 which shows the arc welding method which concerns on Embodiment 1 of this invention.

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

First Embodiment
FIG. 1 is a block diagram of a welding power source for carrying out an arc welding method according to a first embodiment of the present invention. Each block will be described below with reference to the figure.

  Power supply main circuit MC receives a commercial AC power supply (not shown) such as three-phase 200 V, performs output control by inverter control according to a drive signal Dv described later, and outputs welding current Iw and welding voltage Vw. Although not shown, the power supply main circuit MC is a primary rectification circuit that rectifies an alternating current commercial power supply, a capacitor that smoothes the rectified direct current, an inverter circuit that converts the smoothed direct current into high frequency alternating current according to the drive signal Dv, high frequency The high frequency transformer which steps down alternating current to a voltage value suitable for arc welding, the secondary rectification circuit which rectifies the stepped-down high frequency alternating current, and the reactor which smoothes the rectified direct current are provided.

  The welding wire 1 is fed through the welding torch 4 by the rotation of a feed roll 5 coupled to a feed motor WM described later, and an arc 3 is generated between the welding wire 1 and the base material 2. Welding voltage Vw is applied between welding wire 1 and base material 2, and welding current Iw is conducted.

  The steady pulse arc welding period setting circuit T1R outputs a predetermined steady pulse arc welding period setting signal T1r. The first feed speed setting circuit F1R outputs a first feed speed setting signal F1r for setting the feed speed during steady-state pulse arc welding. The first welding voltage setting circuit V1R outputs a first welding voltage setting signal V1r for setting the welding voltage Vw during steady pulse arc welding.

  The short circuit transition welding period setting circuit T2R outputs a predetermined short circuit transition welding period setting signal T2r. The second feed speed setting circuit F2R outputs a second feed speed setting signal F2r for setting the feed speed during the short circuit transition welding period. The second welding voltage setting circuit V2R outputs a second welding voltage setting signal V2r for setting the welding voltage Vw during the short circuit transition welding period.

  The final feed speed change rate setting circuit SER sets a predetermined final feed speed change rate setting signal Ser for setting a change rate of the feed speed when switching from the first feed speed to the second feed speed. Output The final transition period setting circuit TER receives the first feeding speed setting signal F1r, the second feeding speed setting signal F2r, and the final feeding speed change rate setting signal Ser as input, and sets the final transition period setting signal. Output Ter The final transition period setting signal Ter = | F1r-F2r | / Ser. For example, in the case of F1r = 8 m / min, F2r = 2 m / min, and Ser = 0.3 (m / min) / ms, Ter = 20 ms. That is, the final transition period setting signal Ter is a length of time required to change from the first feeding speed to the second feeding speed at the final feeding speed change rate.

  The first stage feed speed change rate setting circuit SSR sets a predetermined start stage feed speed change rate setting signal Ssr for setting the rate of change of the feed speed when switching from the second feed speed to the first feed speed. Output The start transition period setting circuit TSR receives the first feed speed setting signal F1r, the second feed speed setting signal F2r, and the start feed rate change rate setting signal Ssr as input, and sets the start transition period setting signal. Output Tsr. The start transition period setting signal Tsr = | F1r−F2r | / Ssr is calculated. For example, in the case of F1r = 8 m / min, F2r = 2 m / min, and Ssr = 0.15 (m / min) / ms, Tsr = 40 ms. That is, the initial transition period setting signal Tsr is a length of time required to change from the second feeding speed to the first feeding speed at the initial feeding speed change rate.

  The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The average voltage detection circuit VAD receives the voltage detection signal Vd and outputs an average voltage detection signal Vad. The average voltage detection signal Vad is calculated by passing the voltage detection signal Vd through a low pass filter. The voltage error amplification circuit EV amplifies an error between the voltage detection signal Vd and a welding voltage setting signal Vr described later, and outputs a voltage error amplification signal Ev.

  The average voltage error amplification circuit EVA amplifies an error between a welding voltage setting signal Vr described later and the average voltage detection signal Vad to output an average voltage error amplification signal Eva. The pulse cycle timer circuit TFC receives the above average voltage error amplification signal Eva, performs voltage / frequency conversion on the average voltage error amplification signal Eva, and outputs a pulse cycle signal Tf that is briefly set to high level for each pulse cycle. . The peak period timer circuit TPC receives the above-described pulse period signal Tf, and becomes high level during a predetermined peak period each time the pulse period signal Tf changes to high level for a short time, and thereafter becomes low level. Output signal Tpc. A peak period is a peak period when the signal Tpc is at a high level, and a base period when the signal Tpc is at a low level.

The timer circuit TM includes the steady pulse arc welding period setting signal T1r, the final transition period setting signal Ter, the short circuit transition welding period setting signal T2r, the early transition period setting signal Tsr, and the pulse period signal Tf. The following processing is performed with the input as an input and the timer signal Tm is output.
1) During the steady pulse arc welding period determined by the steady pulse arc welding period setting signal T1r, the timer signal Tm = 1 is output.
2) Subsequently, after the period determined by the final transition period setting signal Ter has elapsed, the timer signal Tm = 2 is output during the final transition period until the pulse cycle signal Tf first becomes High level for a short time.
3) Subsequently, the timer signal Tm = 3 is output during a period determined by the short circuit transition welding period setting signal T2r.
4) Subsequently, the timer signal Tm = 4 is output during the initial transition period determined by the initial transition period setting signal Tsr.
5) Repeat the above processes 1) to 4).

Feeding speed setting circuit FR performs the following processing with the above first feeding speed setting signal F1r, the above second feeding speed setting signal F2r and the above timer signal Tm as input, and performs the following processing. Output Fr.
1) When the timer signal Tm = 1 (steady pulse arc welding period), the first feed speed setting signal F1r is output as the feed speed setting signal Fr.
2) When the timer signal Tm = 2 (final transition period), a feeding speed setting signal Fr that changes with a slope from the first feeding speed setting signal F1r to the second feeding speed setting signal F2r is output .
3) When the timer signal Tm = 3 (short-circuit shift welding period), the second feed speed setting signal F2r is output as the feed speed setting signal Fr.
4) When the timer signal Tm = 4 (initial transition period), the feeding speed setting signal Fr changing from the second feeding speed setting signal F2r to the first feeding speed setting signal F1r is outputted. .

  The feed control circuit FC receives the above-described feed speed setting signal Fr, and uses a feed control signal Fc for feeding the welding wire 1 at a feed speed Fw determined by the feed speed setting signal Fr. Output to WM. The feed motor WM feeds the welding wire 1 in accordance with the above feed control signal Fc.

The welding voltage setting circuit VR receives the first welding voltage setting signal V1r, the second welding voltage setting signal V2r, and the timer signal Tm, and performs the following processing to output a welding voltage setting signal Vr. .
1) When the timer signal Tm = 1 (steady pulse arc welding period), the first welding voltage setting signal V1r is output as the welding voltage setting signal Vr.
2) When the timer signal Tm = 2 (final transition period), the welding voltage setting signal Vr which changes with a slope from the first welding voltage setting signal V1r to the second welding voltage setting signal V2r is output.
3) When the timer signal Tm = 3 (short circuit transition welding period), the second welding voltage setting signal V2r is output as the welding voltage setting signal Vr.
4) When the timer signal Tm = 4 (initial transition period), the welding voltage setting signal Vr which changes with a slope from the second welding voltage setting signal V2r to the first welding voltage setting signal V1r is output.

  The peak current setting circuit IPR outputs a predetermined peak current setting signal Ipr. The base current setting circuit IBR outputs a predetermined base current setting signal Ibr.

  The current control setting circuit ICR receives the above peak current setting signal Ipr, the above base current setting signal Ibr and the above peak period signal Tpc as input, and sets the peak current when the peak period signal Tpc is High level (peak period) The signal Ipr is output as the current control setting signal Icr, and when it is low, the base current setting signal Ibr is output as the current control setting signal Icr.

  The current detection circuit ID detects the above-mentioned welding current Iw and outputs a current detection signal Id. The current error amplification circuit EI amplifies an error between the current control setting signal Icr and the current detection signal Id, and outputs a current error amplification signal Ei.

  The welding method switching circuit SM receives the current error amplification signal Ei, the voltage error amplification signal Ev and the timer signal Tm as described above, and when the timer signal Tm = 1, 2 or 4, the current error amplification signal Ei is input. The error amplification signal Ea is output as the error amplification signal Ea, and when the timer signal Tm = 3, the voltage error amplification signal Ev is output as the error amplification signal Ea. As a result, during the initial transition period, the steady pulse arc welding period, and the final transition period, pulse arc welding is performed, and during short circuit transition welding, short circuit transition welding is performed.

  The drive circuit DV performs pulse width modulation control based on the error amplification signal Ea, and outputs a drive signal Dv for driving the inverter circuit of the power supply main circuit MC.

  FIG. 2 is a timing chart of each signal in the welding power source of FIG. 1 showing the arc welding method according to the first embodiment of the present invention. The figure (A) shows the time change of feed speed Fw, the figure (B) shows the time change of welding voltage setting signal Vr, the figure (C) shows the time change of welding current Iw, the figure (D) shows the time change of welding voltage Vw. The operation will be described below with reference to the figure.

  The period of time t1 to t2 is a steady pulse arc welding period, the period of time t2 to t3 is a final transition period, the period of time t3 to t4 is a short circuit transition welding period, and the period of time t4 to t5 is a start period It is a transition period. The stationary pulse arc welding period is set by a stationary pulse arc welding period setting signal T1r. The stationary pulse arc welding period is set to, for example, 500 ms. The final transition period is set as a value obtained by adding a period (about 5 ms) until the end of the pulse period to the period determined by the final transition period setting signal Ter. The final transition period is set to, for example, 20 ms. The short circuit transition welding period is set by the short circuit transition welding period setting signal T2r. The short circuit transfer welding period is set to, for example, 500 ms. The start transition period is set by the start transition period setting signal Tsr. The initial transition period is set to, for example, 40 ms. The initial transition period, the steady pulse arc welding period and the final transition period are pulse arc welding periods.

(1) Operation in the steady pulse arc welding period from time t1 to t2 As shown in FIG. 6A, the feed speed Fw is the first feed speed, and as shown in FIG. The signal Vr becomes a first welding voltage setting signal V1r. The first feeding speed is set by a first feeding speed setting signal F1r. During this period, as shown in FIG. 6C, the peak current and the base current are energized, and as shown in FIG. 4D, the peak voltage and the base voltage are applied. The pulse period at this time is modulated and controlled so that the average value of the welding voltage Vw becomes equal to the welding voltage setting signal Vr. The first feed speed is set to, for example, 8 m / min, and the average value of the welding current Iw at this time is 150A. The first welding voltage setting signal V1r is set to 24 V, for example. The peak current is set to, for example, 450A. The base current is set to, for example, 50A.

(2) Operation of final transition period of time t2 to t3 As shown in FIG. 6A, the feed speed Fw changes from the first feed speed to the second feed speed with a slope. The first delivery rate is greater than the second delivery rate. The change rate of the feed speed Fw during this period is set to be an appropriate value. The rate of change of the feed speed Fw is set by the final feed rate change rate setting signal Ser. Final feed speed change rate setting signal Ser is set to, for example, 0.3 (m / min) / ms. As shown in FIG. 7B, the welding voltage setting signal Vr changes from the first welding voltage setting signal V1r to the second welding voltage setting signal V2r with a slope. During this period, pulse arc welding is performed. This period is a transition period from pulse arc welding to short circuit transition welding. When the rate of change in the feed speed Fw becomes larger than the appropriate range, the change in the melt speed can not follow the change in the feed speed Fw, and the unmelted wire portion is stuck in the molten pool and the welding state is Become unstable. When the rate of change of the feed speed Fw is smaller than the appropriate range, the duration of pulse arc welding becomes longer, the bead appearance becomes worse, and the effect of heat input control is also reduced. Therefore, it is important to set the rate of change of the feed speed Fw in an appropriate range. To this end, the rate of change of the feed speed Fw is set, and the final transition period is calculated from the set rates of the rate of change of the feed speed Fw, the first feed speed and the second feed speed. In this way, the change rate of the feed speed Fw can be maintained at a constant value regardless of the setting values of the first feed speed and the second feed speed, so that the welding state can be stably maintained. Can. Furthermore, since the end point of the final transition period is controlled to be the end point of the pulse cycle, transition to short-circuit transition welding can be made in a state where droplet transition has been completed. Because of this, switching to short circuit transfer welding becomes smooth.

(3) Operation of short-circuit transition welding period from time t3 to t4 As shown in FIG. 6A, the feed speed Fw is the second feed speed, and as shown in FIG. Vr is a second welding voltage setting signal V2r. The second feed speed is set by a second feed speed setting signal F2r. During this period, as shown in FIG. 7C, the welding current Iw increases during the short circuit period and decreases during the arc period. As shown in FIG. 6D, the short circuit voltage value is several volts during the short circuit period, and the arc voltage value is several tens volts during the arc period. Welding voltage Vw is feedback-controlled to be equal to welding voltage setting signal Vr. The second feed speed is set to, for example, 2 m / min, and the average value of the welding current Iw at this time is 50A. The second welding voltage setting signal V2r is set to 17 V, for example.

(4) Operation of Initial Transition Period of Time t4 to t5 As shown in FIG. 6A, the feed speed Fw changes from the second feed speed to the first feed speed with a slope. The change rate of the feed speed Fw during this period is set to be an appropriate value. The rate of change of the feed speed Fw is set by the initial feed rate change rate setting signal Ssr. The initial feed speed change rate setting signal Ssr is set to, for example, 0.15 (m / min) / ms. As shown in FIG. 6B, the welding voltage setting signal Vr changes from the second welding voltage setting signal V2r to the first welding voltage setting signal V1r with a slope. During this period, pulse arc welding is performed. This period is a transition period from short circuit transition welding to pulse arc welding. If the rate of change in the feed speed Fw becomes larger than the appropriate range, the change in the melt speed can not follow the change in the feed speed Fw, and the arc length becomes long and the burnup state occurs, so the welding state becomes unstable. . When the rate of change of the feed speed Fw is smaller than the appropriate range, the duration of pulse arc welding becomes longer, the bead appearance becomes worse, and the effect of heat input control is also reduced. Therefore, it is important to set the rate of change of the feed speed Fw in an appropriate range. To this end, the rate of change of the feed speed Fw is set, and the initial transition period is calculated from the set rates of the rate of change of the feed speed Fw, the first feed speed, and the second feed speed. In this way, the change rate of the feed speed Fw can be maintained at a constant value regardless of the setting values of the first feed speed and the second feed speed, so that the welding state can be stably maintained. Can.

  Hereafter, the effect of the arc welding method which concerns on Embodiment 1 of this invention is demonstrated. According to the invention of the first embodiment, in the arc welding method for alternately switching between pulse arc welding and short circuit transition welding, the period of pulse arc welding is formed from the initial transition period, the steady pulse period and the final transition period , Change from the second feeding speed to the first feeding speed with a slope during the initial transition period, and change with the slope from the first feeding speed to the second feeding speed during the final transition period . Thus, by changing the feed speed in the state of pulse arc welding, it is possible to smoothly switch the welding method. On the other hand, if the welding method is switched by changing the feeding speed in the state of short circuit transition welding, the welding state becomes unstable.

  Furthermore, according to the invention of the first embodiment, the second welding voltage setting value is changed from the second welding voltage setting value to the first welding voltage setting value in the initial transition period, and is changed from the first welding voltage setting value in the final transition period. The second welding voltage setting value is changed with a slope. The welding state can be further stabilized by changing the welding voltage setting value in synchronization with the change of the feeding speed when switching the welding method.

  Furthermore, according to the invention of the first embodiment, the rate of change of the delivery speed during the initial transition period is smaller than the rate of change of the delivery speed during the final transition period. By setting the rate of change of the feed speed during the initial transition period to an appropriate value, it is possible to prevent the burning of the arc. By setting the rate of change of the feeding speed during the final transition period to an appropriate value, it is possible to prevent the welding wire from becoming stuck. By setting the rate of change of the feed rate during the initial transition period to be smaller than the rate of change of the feed rate during the final transition period, it is possible to further stabilize the welding state when switching the welding method.

  Furthermore, according to the invention of the first embodiment, the initial transition period and the final transition period include a plurality of pulse periods. By including a plurality of pulse periods in this manner, it is possible to smooth the change of the arc length accompanying the switching of the welding method.

DESCRIPTION OF SYMBOLS 1 welding wire 2 base material 3 arc 4 welding torch 5 feed roll DV drive circuit Dv drive signal Ea error amplification signal EI current error amplification circuit Ei current error amplification signal EV voltage error amplification circuit Ev voltage error amplification signal EVA average voltage error amplification Circuit Eva Average voltage error amplification signal F1R 1st feeding speed setting circuit F1r 1st feeding speed setting signal F2R 2nd feeding speed setting circuit F2r 2nd feeding speed setting signal FC Feeding control circuit Fc Feeding control signal FR Feeding speed setting circuit Fr Feeding speed setting signal Fw Feeding speed IBR Base current setting circuit Ibr Base current setting signal ICR Current control setting circuit Icr Current control setting signal ID Current detection circuit Id Current detection signal IPR Peak current setting circuit Ipr Peak Current setting signal Iw Welding current MC Power supply main circuit SER Final feed speed change rate setting circuit Ser Final feed speed change Rate setting signal SM Welding method switching circuit SSR First stage feeding speed change rate setting circuit Ssr First stage feeding speed change rate setting signal T1R Steady-state pulse arc welding period setting circuit T1r Steady-state pulse arc welding period setting signal T2R Short-circuit transition welding period setting circuit T2r Short-circuit transition welding period setting signal TER Final transition period setting circuit Ter Final transition period setting signal TFC Pulse period timer circuit Tf Pulse period signal TM Timer circuit Tm Timer signal TPC Peak period timer circuit Tpc Peak period signal TSR Peak transition period setting circuit Tsr Start period Transition period setting signal V1R first welding voltage setting circuit V1r first welding voltage setting signal V2R second welding voltage setting circuit V2r second welding voltage setting signal VAD average voltage detection circuit Vad average voltage detection signal VD voltage detection circuit Vd voltage detection signal VR welding voltage setting circuit Vr welding voltage setting signal w welding voltage WM feed motor

Claims (4)

The welding voltage corresponding to the first welding voltage setting value is output, the welding wire is fed at the first feeding speed, and the period when pulse arc welding is performed, and the welding voltage corresponding to the second welding voltage setting value is output. In the arc welding method, in which the wire is fed at a second feed speed and the period during which short circuit transition welding is performed is alternately switched and welding is performed,
The period of the pulse arc welding is formed of an initial transition period, a steady pulse period and a final transition period,
Changing from the second feeding speed to the first feeding speed with a slope during the initial transition period,
Changing from the first feeding speed to the second feeding speed with a slope during the final transition period,
Arc welding method characterized by The second welding voltage setting value is changed from the second welding voltage setting value to the first welding voltage setting value during the initial transition period,
In the final transition period, the first welding voltage set value is changed from the first welding voltage set value to the second welding voltage set value with a slope.
The arc welding method according to claim 1, characterized in that: The rate of change of the delivery rate during the initial transition period is smaller than the rate of change of the delivery rate during the final transition period,
The arc welding method according to claim 1 or 2 characterized by things. The arc welding method according to any one of claims 1 to 3, wherein the initial transition period and the final transition period include a plurality of pulse periods.

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