JP2023010100A - Arc-welding control method - Google Patents

Abstract

To uniformize a bead width even if the changeable control of welding wire-feeding speed is performed so that the average value of welding current becomes constant when the distance between a power-feeding chip and a base material changes.SOLUTION: An arc-welding control method comprises welding a welding wire while performing the changeable control of a welding wire-feeding speed Fw so that the average value Iwa of a welding current becomes a prescribed value. In the control method, correction is performed so that a welding speed Sw becomes fast when the feeding speed Fw becomes fast by speed-changeable control and on the contrary, the speed Sw becomes slow following a slow speed of Fw. The welding speed Sw is corrected so that the feeding amount per unit welding length becomes constant.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding control method for performing welding by variably controlling the feeding speed of a welding wire so that the average value of welding current becomes a predetermined value.

An arc welding control method is commonly used in which welding is performed by variable-speed control of the feeding speed of the welding wire so that the average value of the welding current becomes a predetermined value (see Patent Document 1). In normal consumable electrode arc welding, the feed rate is constant during welding. On the other hand, in the invention of Patent Document 1, the feed speed is variable-speed controlled so that the average value of the welding current is constant even if the distance between the power feeding tip and the base metal changes. Since the penetration depth of the base metal is approximately proportional to the average value of the welding current, the penetration depth becomes uniform when the average value of the welding current becomes constant. In normal arc welding, welding is performed while maintaining a constant distance between the power supply tip and the base material. However, in the case of deep groove welding, multi-layer welding, etc., it may be difficult to keep the distance between the power supply tip and the base material at a constant value due to problems such as interference between the welding torch and the base material. . In welding in which the distance between the power supply tip and the base metal varies in this way, the invention of Patent Document 1 maintains the average value of the welding current constant by variable speed control of the feed speed, so it is one of the important welding quality. It is possible to suppress fluctuations in the penetration depth, which is one of them, and to make it uniform.

JP-A-7-51854

If the feeding speed is variable as in the prior art, the penetration depth can be made uniform even if the distance between the feeding tip and the base material fluctuates. However, if the feed speed changes greatly, the welding speed is a constant value, so there is a problem that the bead width fluctuates.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an arc welding control method capable of uniformizing the bead width even when the feed speed is variable.

In order to solve the above-mentioned problems, the invention of claim 1 is
In an arc welding control method for performing welding by variable-speed control of the welding wire feed speed so that the average value of the welding current is a predetermined value,
By the variable speed control, when the feed speed changes to increase, the welding speed is corrected to increase, and when the feed speed changes to decrease, the welding speed decreases. fix,
An arc welding control method characterized by:

The invention of claim 2 is
The welding speed is modified so that the feed rate per unit weld length is constant.
The arc welding control method according to claim 1, characterized in that:

The invention of claim 3 is
The rate of change of the feed speed is a value smaller than the maximum value of the rate of change of the welding speed.
The arc welding control method according to claim 1 or 2, characterized in that:

According to the present invention, the bead width can be made uniform even if the feeding speed is variable.

1 is a configuration diagram of a welding device for carrying out an arc welding control method according to an embodiment of the present invention; FIG. 2 is a timing chart of each signal in the welding apparatus of FIG. 1, showing the arc welding control method according to the 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 configuration diagram of a welding apparatus for carrying out an arc welding control method according to an embodiment of the present invention. Hereinafter, each component will be described with reference to the same figure.

Welding power supply PS receives an AC commercial power supply (not shown) such as 3-phase 200 V, performs output control such as inverter control, and outputs welding voltage Vw and welding current Iw for generating arc 3 . Welding power source PS is a power source with constant voltage characteristics for performing consumable electrode arc welding.

A welding current setting circuit IR outputs a predetermined welding current setting signal Ir for setting the average value of the welding current Iw.

A welding current average value detection circuit ID detects the average value of the welding current Iw and outputs a welding current average value detection signal Id.

A current error amplification circuit EI receives the welding current setting signal Ir and the welding current average value detection signal Id, amplifies the error between the two values, and outputs a current error amplification signal Ei.

The feeding speed setting circuit FR outputs a predetermined feeding speed setting signal Fr as an initial value.

A feeding speed correction circuit FCR receives the feeding speed setting signal Fr and the current error amplification signal Ei, calculates Fcr=Fr+∫Ei·dt, and outputs a feeding speed correction signal Fcr. This circuit performs variable speed control so that the value of the welding current average value detection signal Id becomes equal to the value of the welding current setting signal Ir, and outputs the feed speed correction signal Fcr.

The welding speed setting circuit SR outputs a predetermined welding speed setting signal Sr as an initial value.

The welding speed correction circuit SCR receives the welding speed setting signal Sr, the feed speed setting signal Fr, and the feed speed correction signal Fcr as inputs.
Fcr=Sr.times.(Fcr/Fr) --Equation (1) is calculated to output the welding speed correction signal Scr. As a result, when the value of the feed speed correction signal Fcr increases, the value of the welding speed correction signal Scr is corrected to increase by the variable speed control, and the value of the feed speed correction signal Fcr decreases. , the value of the welding speed correction signal Scr is corrected to be slow. As a result, even if the feeding speed Fw changes due to the variable speed control, the bead width can be made uniform. Furthermore, when the welding speed correction signal Scr is output based on the above equation (1), the feed amount per unit weld length (the integrated value of the feed speed correction signal Fcr) becomes constant, so that the bead width is further reduced. can be homogenized.

Here, it is preferable that the rate of change of the feed speed correction signal Fcr is smaller than the maximum value of the rate of change of the welding speed correction signal Scr. In general, the rate of change in acceleration/deceleration of the welding speed Sw by a robot, an automatic cart, or the like is smaller than the rate of change in acceleration/deceleration of the feed speed Fw by the feeder WF. For this reason, if the rate of change of the feed speed Fw is larger than the maximum value of the rate of change of the welding speed Sw, the correction of the welding speed Sw responds sufficiently to changes in the feed speed Fw by the variable speed control. It may not be possible. In order to suppress this, the above conditions are added.

The feeder WF feeds the welding wire 1 at a feed speed Fw corresponding to the feed speed correction signal Fcr.

The welding torch WT feeds the welding wire 1 to the welded portion of the base material 2 by supplying power to the welding wire 1 via a power supply tip (not shown) attached thereto. An arc 3 is generated between the welding wire 1 and the base material 2 . A welding voltage Vw is applied between the power supply tip and the base material 2, and a welding current Iw is applied.

The robot RM is equipped with the welding torch WT, and moves at a welding speed Sw according to an operation control signal Mc, which will be described later.

The robot controller RC receives the welding speed correction signal Scr as an input and moves the robot RM along the weld line at the welding speed Sw determined by the welding speed correction signal Scr according to a predetermined work program. It outputs a control signal Mc.

FIG. 2 is a timing chart of each signal in the welding apparatus of FIG. 1 showing the arc welding control method according to the embodiment of the present invention. (A) shows the time change of the feed tip-base material distance Lw, (B) shows the time change of the feed speed Fw, and (C) shows the time change of the welding speed Sw. , and (D) shows the time change of the welding current average value Iwa. The operation of each signal will be described below with reference to FIG.

In the figure, as shown in (A) of the same figure, the distance Lw between the power feeding tip and the base material is a predetermined appropriate reference distance during the period from time t1 to t2, and The distance is longer than the reference distance, and the distance is shorter than the reference distance during the period from time t3 to t4.

During the period from time t1 to t2, the distance Lw between the power feeding tip and the base material is the reference distance, so the feed speed Fw is determined by the feed speed setting signal Fr shown in FIG. 1, as shown in FIG. As shown in FIG. 1(C), the welding speed Sw becomes a value determined by the welding speed setting signal Sr of FIG. Then, as shown in FIG. 1(D), the welding current average value Iwa is determined by adjusting the feed speed Fw so that the value of the welding current setting signal Ir shown in FIG. 1 becomes equal to the value of the welding current average value detection signal Id. Since the speed change control is performed, the value of the welding current setting signal Ir is maintained throughout the entire period.

During the period from time t2 to t3, when the distance Lw between the power feeding tip and the base material changes to a distance longer than the reference distance, as shown in FIG. Due to the variable speed control by the correction circuit FCR, the speed changes with a slope faster than during the period from time t1 to t2. Then, as shown in FIG. 1C, the welding speed Sw becomes faster than during the period from time t1 to t2 because the welding speed correction circuit SCR of FIG. so that it has a slope that changes. As a result, the feed tip-to-base material distance Lw changes, and the welding speed Sw changes according to the change in the feed speed Fw, so that the bead width can be made uniform. Furthermore, if the welding speed Sw is changed based on the above formula (1), the feeding amount per unit welding length can be made constant, so that the bead width can be made more uniform.

During the period from time t3 to t4, when the distance Lw between the power feeding tip and the base material changes to a distance shorter than the reference distance, the feed speed Fw changes from the feed speed shown in FIG. 1, as shown in FIG. Due to the variable speed control by the correction circuit FCR, the speed changes with a slope slower than during the period from time t1 to t2. Then, as shown in FIG. 1C, the welding speed Sw is changed with a slope so that the feed speed Fw is slowed down by the welding speed correction circuit SCR of FIG. Change to be slower than medium. As a result, the feed tip-to-base material distance Lw changes, and the welding speed Sw changes according to the change in the feed speed Fw, so that the bead width can be made uniform. Furthermore, if the welding speed Sw is changed based on the above formula (1), the feeding amount per unit welding length can be made constant, so that the bead width can be made more uniform.

Here, the slope (rate of change) of the feed speed Fw is preferably smaller than the maximum value of the slope (rate of change) of the welding speed Sw. In general, the rate of change in acceleration/deceleration of the welding speed Sw by a robot, an automatic cart, or the like is smaller than the rate of change in acceleration/deceleration of the feed speed Fw by the feeder WF. For this reason, if the rate of change of the feed speed Fw is larger than the maximum value of the rate of change of the welding speed Sw, the correction of the welding speed Sw responds sufficiently to changes in the feed speed Fw by the variable speed control. There are cases where it is not possible. In order to suppress this, it is preferable to add the above conditions.

1 welding wire
2 Base material
3 Arc FCR Feeding speed correction circuit Fcr Feeding speed correction signal FR Feeding speed setting circuit Fr Feeding speed setting signal Fw Feeding speed ID Welding current average value detection circuit Id Welding current average value detection signal IR Welding current setting circuit Ir Welding current setting signal Iw Welding current PS Welding power source RC Robot controller RM Robot SCR Welding speed correction circuit Scr Welding speed correction signal SR Welding speed setting circuit Sr Welding speed setting signal Sw Welding speed Vw Welding voltage WF Feeder WT Welding torch

Claims (3)

In an arc welding control method for performing welding by variable-speed control of the welding wire feed speed so that the average value of the welding current is a predetermined value,
By the variable speed control, when the feed speed changes to increase, the welding speed is corrected to increase, and when the feed speed changes to decrease, the welding speed decreases. fix,
An arc welding control method characterized by: The welding speed is modified so that the feed rate per unit weld length is constant.
The arc welding control method according to claim 1, characterized by: The rate of change of the feed speed is a value smaller than the maximum value of the rate of change of the welding speed.
The arc welding control method according to claim 1 or 2, characterized in that:

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