JP2023075387A - Welding end control method for consumable electrode arc welding - Google Patents

Abstract

To perform satisfactory welding end control corresponding to various welding conditions in consumable electrode arc welding.SOLUTION: A welding end control method for consumable electrode arc welding is provided in which, when a welding end signal On is inputted to a welding power source at a time t1, a feeding motor stops driving, and a short circuit period and an arc period are repeated during an anti-stick period until welding ends after a feeding speed of the feeding motor transiently decreases due to inertia and stops. In the welding end control method, when a final arc period from a time t11 after the short circuit period is repeated a predetermined number of times is determined during an anti-stick period from the time t1 to a time t2, an output of the welding power source is stopped at the time t2. During the anti-stick period from the time t1 to t2, an increase rate of welding current Iw during the short circuit period is made larger than that during a steady welding period at and before the time t1.SELECTED DRAWING: Figure 2

Description

The present invention relates to a welding end control method for consumable electrode arc welding.

In consumable electrode arc welding, it prevents the welding wire from sticking to the molten pool at the end of welding, and optimizes the size of the wire tip grain formed at the end of welding to improve the next arc startability. Welding end control (anti-stick control) is performed for Welding end control is the control of the welding current and welding voltage during the inertia period from when a welding end signal is input to the welding power source until the feed motor stops due to transient deceleration due to inertia (for example, Patent Document 1 reference).

JP 2015-16487 A

In the prior art, it was difficult to always optimize the size of the wire tip grain formed at the end of welding under various welding conditions such as the deceleration state of the feed motor, welding posture, and joint shape. For this reason, the size of the grain at the tip of the wire may become too large or too small, and there is a problem that the next arc startability is deteriorated. In particular, when the shielding gas is 100% carbon dioxide, this problem becomes significant.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method of controlling the end of welding that is suitable for various welding conditions in consumable electrode arc welding.

In order to solve the above-mentioned problems, the invention of claim 1 is
When a welding end signal is input to the welding power source, the feed motor stops driving, and the feed motor is transiently decelerated by inertia and stopped. In a welding termination control method for consumable electrode arc welding in which welding is terminated by repeating an arc period,
stopping the output of the welding power source when determining the final arc period after repeating the short-circuit period a predetermined number of times during the anti-stick period;
A welding end control method for consumable electrode arc welding characterized by:

The invention of claim 2 is
making the rate of increase of the welding current during the short-circuit period greater during the anti-stick period than during the steady welding period;
The welding end control method for consumable electrode arc welding according to claim 1, characterized in that:

The invention of claim 3 is
stopping the output of the welding power source when it is determined that the duration of the final arc period has reached a reference time;
The welding end control method for consumable electrode arc welding according to claim 1 or 2, characterized in that:

According to the present invention, in consumable electrode arc welding, it is possible to provide a good welding end control method corresponding to various welding conditions.

1 is a block diagram of a welding power source PS for carrying out a welding end control method for consumable electrode arc welding according to an embodiment of the present invention; FIG. 2 is a timing chart of each signal in the welding power source of FIG. 1, showing a welding end control method for consumable electrode arc welding according to an embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a welding power supply PS for implementing a welding end control method for consumable electrode arc welding according to an embodiment of the present invention. Each block will be described below with reference to FIG.

The power supply main circuit PM receives a commercial power supply (not shown) such as 3-phase 200 V, and performs output control such as inverter control according to a drive signal Dv described later to set the welding voltage Vw and welding current Iw suitable for arc welding. Output. Although not shown, the power supply main circuit PM includes a primary rectifier circuit that rectifies commercial power, a capacitor that smoothes the rectified direct current, and an inverter circuit that is driven by a drive signal Dv that converts the smoothed direct current into high-frequency alternating current. , a high-frequency transformer for stepping down high-frequency alternating current to a voltage suitable for arc welding, a secondary rectifier circuit for rectifying the stepped-down high-frequency alternating current, and a reactor for smoothing the rectified direct current.

The output voltage detection circuit ED detects the output voltage E rectified by the secondary rectifier circuit of the power supply main circuit PM and outputs an output voltage detection signal Ed.

Welding wire 1 is fed through welding torch 4 by rotation of feed roll 5 coupled to feed motor M, and arc 3 is generated between work 2 and welding wire 1 . A welding voltage Vw is applied between the welding wire 1 and the workpiece 2, and a welding current Iw is applied. Shielding gas (not shown) is jetted out from the tip of the welding torch 4 .

The welding start/end circuit ON outputs a welding start/end signal On that becomes High level (welding start signal) when welding is started and becomes Low level (welding end signal) when welding is ended. This circuit is a switch attached to the welding torch 4 . Also, this circuit is built into the robot controller in the case of robot welding.

A welding current setting circuit IR outputs a predetermined welding current setting signal Ir.

A feeding speed setting circuit FR receives the welding current setting signal Ir and outputs a feeding speed setting signal Fr calculated by a predetermined current/feeding speed conversion function.

A feeding speed detection circuit FD receives a rotation speed signal from the feeding motor M, converts it into a feeding speed, and outputs a feeding speed detection signal Fd. The rotational speed signal is a signal from an encoder provided in the feeding motor M, an armature voltage signal, or the like.

A welding voltage detection circuit VD detects the welding voltage Vw and outputs a welding voltage detection signal Vd. A welding current detection circuit ID detects the welding current Iw and outputs a welding current detection signal Id.

The short-circuit discrimination circuit SD receives the welding voltage detection signal Vd, and when this value is less than the short-circuit discrimination value (approximately 10 V), it discriminates that it is in the short-circuit period and becomes High level. It determines that there is a short circuit and outputs a short-circuit determination signal Sd that becomes Low level.

The reference number setting circuit NR outputs a predetermined reference number setting signal Nr. A final arc period setting circuit TAR outputs a predetermined final arc period setting signal Tar.

The output stop circuit OFF receives the welding start/end signal On, the short circuit determination signal Sd, the reference number of times setting signal Nr, and the final arc period setting signal Tar, and the welding start/end signal On is Low. level to enter the anti-stick period Ta, the number of times the short circuit determination signal Sd changes to High level (short circuit) becomes equal to the value of the reference number setting signal Nr, and the duration of the final arc period after that is the final arc period. When the value set by the setting signal Tar is reached, the output stop signal Off is output which becomes High level for a short period of time.

The feed control circuit FC receives the welding start/end signal On and the feed speed setting signal Fr as inputs, performs the following processing, and generates a feed control signal Fc for controlling the feed motor M. to output
1) When the welding start/end signal On is at High level (welding start signal), the welding wire 1 is fed at a constant speed at a feed speed set by the feed speed setting signal Fr.
2) When the welding start/end signal On changes to the Low level (welding end signal) and the anti-stick period Ta begins, the drive of the feed motor M is stopped. As a result, the feeding speed is reduced to 0 by inertia.

The feeding motor M has its rotation speed controlled by the feeding control signal Fc, and feeds the welding wire 1 at the feeding speed.

A steady welding voltage setting circuit VCR outputs a predetermined steady welding voltage setting signal Vcr.

An anti-stick welding voltage setting circuit VAR receives the feed speed detection signal Fd and outputs an anti-stick welding voltage setting signal Var set by a predetermined function with the feed speed detection signal Fd as an input.

The welding voltage setting circuit VR receives the above welding start/end signal On, the above steady welding voltage setting signal Vcr and the above antistick welding voltage setting signal Var as inputs, performs the following processing, and outputs the welding voltage setting signal Vr. Output.
1) When the welding start/end signal On is at High level during the steady welding period Tc, the steady welding voltage setting signal Vcr is output as the welding voltage setting signal Vr.
2) When the welding start/end signal On is in the low level anti-stick period Ta, the anti-stick welding voltage setting signal Var is output as the welding voltage setting signal Vr.

The amplification factor setting circuit LR receives the welding start/end signal On as an input, and during the steady welding period when the welding start/end signal On is at a high level, the gain setting circuit LR becomes a predetermined steady welding period amplification factor, and the welding start/end signal During the anti-stick period Ta in which On is at Low level, it outputs the amplification factor setting signal Lr that has a predetermined anti-stick period amplification factor. The amplification factor of the electronic reactor control is set according to the value of the amplification factor setting signal Lr. where anti-stick period gain<steady welding period gain.

A welding voltage control setting circuit VER receives the welding voltage setting signal Vr, the welding current detection signal Id, and the amplification factor setting signal Lr as inputs, and calculates Ver=Vr−Lr×dId/dt to perform welding. It outputs the voltage control setting signal Ver. This circuit is a circuit that performs well-known electronic reactor control, and can change the rate of increase of the welding current Iw during the short-circuit period according to the value of the amplification factor setting signal Lr. Here, since the value of the amplification factor setting signal Lr is smaller during the anti-stick period Ta than during the steady welding period Tc, the rate of increase of the welding current Iw during the short circuit period is increased.

A voltage error amplification circuit EV amplifies an error between the welding voltage control setting signal Ver and the output voltage detection signal Ed to output a voltage error amplification signal Ev.

The drive circuit DV receives the welding start/end signal On, the output stop signal Off, and the voltage error amplification signal Ev as inputs, and operates from the time the welding start/end signal On changes to a high level (start of welding). During the period until the output stop signal OFF goes high for a short period of time, the drive signal Dv for driving the power supply main circuit PM is output based on the voltage error amplification signal Ev. Therefore, the welding power source PS performs output control during the steady welding period Tc and the anti-stick period Ta.

FIG. 2 is a timing chart of each signal in the welding power source of FIG. 1 showing the welding end control method for consumable electrode arc welding according to the embodiment of the present invention. (A) shows the change over time of the welding start/end signal On, (B) shows the change over time of the feed speed, and (C) shows the change over time of the welding current Iw. (D) shows the time change of the welding voltage Vw, (E) shows the time change of the welding voltage setting signal Vr, (F) shows the time change of the drive signal Dv, and (G) shows the time change of the drive signal Dv. indicates the time change of the output stop signal OFF. The operation of each signal will be described below with reference to FIG.

In the figure, the period before time t1 is the steady welding period Tc. The period from time t1 to t2 is the anti-stick period Ta. Then, at time t2, as shown in (G) of the figure, when the output stop signal Off goes high for a short period of time, the anti-stick period Ta ends, the welding power source stops outputting, and welding ends.

(1) Operation during steady welding period Tc before time t1 During this period, the welding start/end signal On is at High level (welding start) as shown in FIG. Then, as shown in FIG. 1B, the feeding speed becomes the value set by the feeding speed setting signal Fr of FIG. As shown in (E) of the figure, the welding voltage setting signal Vr has a value set by the steady welding voltage setting signal Vcr in FIG. Voltage controlled. As shown in (D) of the figure, the welding voltage Vw repeats a short-circuit period in which the short-circuit voltage value is several volts and an arc period in which the arc voltage value is several tens of volts. As shown in (C) of the figure, the welding current Iw gradually increases during the short circuit period and gradually decreases during the arc period. The rate of increase of the welding current Iw during the short-circuit period is controlled (electronic reactor control) by the value of the gain setting signal Lr in FIG. As shown in (F) of the figure, the drive signal Dv is at a high level until time t2 and the welding power source performs output, and at time t2 it is at a low level and the welding power source stops outputting.

(2) Operation during anti-stick period Ta from time t1 to t2)
At time t1, the welding start/end signal On changes from High level (welding start) to Low level (welding end) as shown in FIG. In response to this, the driving of the feeding motor M is stopped, so that the feeding speed is reduced by inertia and becomes 0 at time t12, as shown in FIG. As shown in (E) of the figure, the welding voltage setting signal Vr decreases linearly or curvedly along with the deceleration of the feed speed, and when it reaches a predetermined value, it maintains that value. The welding voltage setting signal Vr during this period is set by the anti-stick welding voltage setting signal Var of FIG. The value of the anti-stick welding voltage setting signal Var is a function of inputting the feed speed detection signal Fd of FIG. By doing so, the change in the average value of the welding voltage Vw becomes gentler, and the welding state becomes more stable. During this period, the short-circuit period and the arc period are repeated as shown in (C) and (D) of the figure. The rate of increase of the welding current Iw during the short circuit period in the anti-stick period Ta is higher than during the steady welding period Tc before time t1. This is because the value of the amplification factor setting signal Lr in FIG. 1 for electronic reactor control is set to a smaller value during the anti-stick period Ta than during the steady welding period Tc. In this way, the rate of increase of the welding current Iw during the short-circuit period increases, and the number of short-circuits increases, thereby stabilizing the burning of the welding wire tip during the arc period.

Then, when the number of short-circuit periods becomes equal to the value of the reference number-of-times setting signal Nr in FIG. 1, the short circuit is released at time t11 immediately before the feeding speed becomes 0, and the final arc period begins. As shown in (C) of the figure, the welding current Iw during the final arc period is a small current value of several tens of amperes. At time t2, when the duration of the final arc period reaches the value of the final arc period setting signal Tar shown in FIG. 1, the output stop signal Off goes high for a short period of time as shown in FIG. 1(G). In response to this, the driving signal Dv changes to the low level as shown in (F) of the figure, and the welding power supply stops outputting. As a result, at time t2, the arc is extinguished, the welding current Iw becomes 0A as shown in (C) of the same figure, and the welding voltage Vw also becomes 0V as shown in (D) of the same figure. For example, the reference number is 5 times, the final arc period is 4 ms, and the anti-stick period is about 100 ms.

The effects of this embodiment will be described below.
According to this embodiment, the output of the welding power source is stopped when the final arc period after repeating the short-circuit period a predetermined number of times during the anti-stick period is determined. In this way, welding can be terminated when the arc state reaches a desired state under various welding conditions. As a result, in the present embodiment, it is possible to prevent welding at the end of welding and optimize the size of the wire tip grain under various welding conditions.

More preferably, according to the present embodiment, the welding current increase rate during the short-circuit period is made greater during the anti-stick period than during the steady welding period. If the rate of increase of the welding current during the short circuit period is increased, the number of short circuits increases, so the burning of the welding wire tip during the arc period is stabilized. As a result, the size of the wire tip grains at the end of welding can be made more uniform.

More preferably, according to this embodiment, the output of the welding power source is stopped when it is determined that the duration of the final arc period has reached the reference time. By doing so, the size of the wire tip grains at the end of welding can be made more uniform.

1 Welding wire 2 Work 3 Arc 4 Welding torch 5 Feed roll DV Drive circuit Dv Drive signal E Output voltage ED Output voltage detection circuit Ed Output voltage detection signal EV Voltage error amplification circuit Ev Voltage error amplification signal FC Feed control circuit Fc Feed Feed control signal FD Feed speed detection circuit Fd Feed speed detection signal FR Feed speed setting circuit Fr Feed speed setting signal ID Welding current detection circuit Id Welding current detection signal IR Welding current setting circuit Ir Welding current setting signal Iw Welding current LR Amplification setting circuit Lr Amplification setting signal M Feeding motor NR Reference number setting circuit Nr Reference number setting signal OFF Output stop circuit OFF Output stop signal ON Welding start/end circuit ON Welding start/end signal PM Power supply main circuit PS Welding Power supply SD Short-circuit discrimination circuit Sd Short-circuit discrimination signal TAR Final arc period setting circuit Tar Final arc period setting signal VAR Anti-stick welding voltage setting circuit Var Anti-stick welding voltage setting signal VCR Regular welding voltage setting circuit Vcr Regular welding voltage setting signal VD Welding voltage Detection circuit Vd Welding voltage detection signal VER Welding voltage control setting circuit Ver Welding voltage control setting signal VR Welding voltage setting circuit Vr Welding voltage setting signal Vw Welding voltage

Claims (3)

When a welding end signal is input to the welding power source, the feed motor stops driving, and the feed motor is transiently decelerated by inertia and stopped. In a welding termination control method for consumable electrode arc welding in which welding is terminated by repeating an arc period,
stopping the output of the welding power source when determining the final arc period after repeating the short-circuit period a predetermined number of times during the anti-stick period;
A welding end control method for consumable electrode arc welding, characterized by: making the rate of increase of the welding current during the short-circuit period greater during the anti-stick period than during the steady welding period;
The welding end control method for consumable electrode arc welding according to claim 1, characterized in that: stopping the output of the welding power source when it is determined that the duration of the final arc period has reached a reference time;
The welding end control method for consumable electrode arc welding according to claim 1 or 2, characterized in that:

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