JPS58176074A - Consumable electrode type pulse arc welding method - Google Patents

Abstract

PURPOSE:To suppress irregular rocking of a welding metal and to obtain stable penetration, by periodically varying a peak current value of a welding current having a pulse waveform, in case of consumable pulse arc welding. CONSTITUTION:A peak value Ip of a welding current (i) controlled to a pulse waveform is controlled, for instance, to a sine wave, so that it is varied periodically within a range of a current which is larger than a critical current value Ic. In accordance with this variation period, arc force is varied, a weld metal of a molten pool 7 follows little by little in the advancing direction of a wire 8. Accordingly, stable penetration which scarcely causes variance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a consumable electrode type pulse arc welding method which is aimed at stabilizing penetration.

Conventionally, the consumable electrode type arc has GCh gas as the main component and is used as a shield gas.
! In the tangential method, as shown in Fig. 1, there is a technique in which the current i flowing through the wire circuit is sprayed from a relatively low current range as a pulsed current controlled by a thyristor or power transistor to a constant peak [LITlK]. .

(Hereinafter referred to as the pulsed MAG#lW method) According to this method, a current higher than the critical current Ic at which the wire sprays transfers can be passed in an extremely short interval by utilizing the sharp rise of the pulsed tc current. By utilizing the periodic pinch effect, it becomes stable granular droplets and can be transferred to the base material, making #l contact with less spatter possible.

However, it has been found that when this conventional method is used, intermittent arc heat and molten metal formed by droplets cannot be controlled at all, and the molten metal scrapes irregularly. In other words, the molten metal oscillates due to the balance of arc force, gravity, and surface tension, and there are two cases: when the molten metal advances to just below the arc, and when the molten metal retreats from just below the arc, the solid direction of the Kt material directly below the arc is set. It is K that occupies an irregular place t in the leap up to the case where

Compared to the continuous movement of the wire, the molten metal 114 moves intermittently and irregularly, causing the molten pool to fluctuate irregularly. Due to this rule, the conditions of the base metal exposed to the arc varied irregularly, resulting in unstable penetration even if the heat input was completely uniform.

An object of the present invention is to stabilize penetration by controlling the movement of the molten pool (VCL) as described above, which has not been achieved with the prior art.

In order to achieve this object, in the consumable electrode type pulsed arc welding method of the present invention, the peak current of the #l contact current having a pulse waveform 1 fluctuates periodically in a region equal to or higher than the critical current value for spray transfer. controlled as follows. From this K, the arc force applied to the molten pool changes periodically, ・#l
l Gold metal is given a small fluctuation force.

This K suppresses irregular fluctuations of the molten metal, and #l
Stable penetration can be obtained by advancing gold metal in small increments.

Hereinafter, a preferred embodiment of the present invention will be explained with reference to the drawings.

Figure 2 shows the waveform 1 of the #contact current according to an embodiment of the present invention, where i is the average of the S* current that can be read with an ammeter, etc. The value Ic is the critical current value at which spray transfer is possible.

In addition, within the range of the current that is controlled by the pulse waveform and is larger than the peak value of the S contact current 1, the critical current value Ia,
In the case of 0 lines, which is controlled to fluctuate in 8 periods.

The waveform connecting the peak value Ipt is controlled to be a sine wave that fluctuates at a regular period τ. The waveform of the beater value Ip of this welding current is not a sine *K11J+ but another waveform, and is 4 times.

What is the fluctuation in the peak value Ip of the S* current?

For example, it can be obtained by constructing a welding power supply circuit as shown in FIG. II! In Figure 3, 1 is a transformer and 2 is a rectifier R circuit. 3 is a group of power transistors for base current setting, and 4 is a group of power transistors for pulse current, 69. These combined currents flow through the output. Reference numeral 6 denotes a sine wave signal generator, and the amplitude II and wave number of the sine wave can be arbitrarily controlled. 5 is a pulse generator.

The output pulse train of the pulse generator 5 is completely amplitude-modulated by the output of the sine wave signal generator 6. This amplitude-modulated output pulse train is amplified by the power transistor group 4 and becomes the beak bath current RIp.

In the consumable electrode type pulsed arc welding method of the present invention, the peak value of the welding current of the pulse waveform changes synchronously, so that the arc force changes in accordance with the period of this fluctuation. Due to this fluctuation of the arc force, as shown in Fig. 4, a constantly fluctuating force is applied to the molten pool 7, which maintains its shape due to the balance of arc force, gravity, and surface tension, or which oscillates due to loss of balance. The Rukoto. By applying this fluctuating force, the molten metal in the molten pool 7 has the same surface tension and arc force as the molten metal.

Since the balance with gravity will be disrupted in small increments, the wire 8 can be moved without large irregular movements.
As the wire progresses, it follows the wire in small increments in the direction of wire movement. Therefore, in the method of the present invention, small fluctuations in penetration occur, but large irregular fluctuations do not occur in the conventional method.Moreover, such fluctuations tl - peak current value Ip of the welding current to be generated The fluctuation of critical current value I
Since Cj is also carried out in a high region, it has no effect on the spray transfer of droplets, therefore #1
The spray transfer of droplets is stable and constant state is maintained as in the pulsed MAG agitation method.

Such good sex I! The weld bead obtained by the welding method of the present invention, which exhibits the following properties, is compared with that of the conventional pulsed MAG method and is shown in FIGS. 5 and 6. ! - was obtained by conventional pulse MAG welding method. It shows a cross section of a weld bead 9 cut in the weld line direction on a single plate.

This welding was performed with S*current I = 31OA, arc voltage -30V, 5atat-so/min, Y@yc
w-2・φL! Welding was carried out under the following welding conditions: fin, base material: mild steel, plate thickness: 5 mm, using transistor-controlled pulse MAGII@I. The ms diagram shows a cross section in the bath tangent direction of a weld bead 10 obtained by the welding method of the present invention and similar to that shown in FIG. In this welding, the peak value Ip of the welding current of the pulse waveform shown in Fig. 2 is controlled to a 9 sine wave using the circuit shown in Fig. 3, and the period τ of the sine wave is
The welding was carried out under controlled welding conditions, with tα being controlled at 07 seconds. Comparing the pipes in Figures 5 and 6, it is clear that there is a slight variation in penetration depth in the present invention.

It is much more stable and achieves deeper penetration than conventional methods.

This integration #! The variation in height is due to the peak electric current of 1% Ei engineering p.
However, as shown in Figure 7, the period τi of the ripple wave of the bead also changes with +\ short synchronization τ.
By setting #! It can be seen that it is possible to reduce the variation in the thickness, and therefore, by setting appropriate conditions, it is possible to obtain a bead with good machining.

As described above, when using the consumable electrode type pulsed arc welding method of the present invention, the conventional pulsed M
Molten metal movement that could not be achieved with the AG welding method! ! It is possible to control the tube, thereby making it possible to obtain a stable and constant penetration t with little variation.

[Brief explanation of the drawing]

The first diagram shows the conventional consumable electrode pulsed arc welding method #! Waveform diagram of contact current. FIG. 2 is a waveform diagram of welding current in the consumable electrode type pulsed arc welding method of the present invention. Figure 3 is a circuit diagram of a welding power supply circuit that fully controls the S contact current in Figure F1m2. Figure g4 is a sectional view showing the state of the welded part. FIG. 5 is a cross-sectional view of a friend weld bead obtained by the conventional consumable electrode type pulsed arc welding method. FIG. 6 shows the relationship between the fluctuation period of the peak current value and the dispersion of the penetration depth. It is. Ding: Average IIl contact current. Ic... Spray transfer critical current. Ip--Peak current. 1. Fist... Welding current. τ･･･Fluctuating period. τ Cao...@φ bead ripple wave period. 1...Trance. 2...e-rectifier circuit. 3... Base current setting transistor group. No. 010. Power transistor group for pulse current. 50... Pulse generator. 6... Sine wave signal generator. , 7... Molten pool. 9. lO... Welding bead.

Claims (2)

[Claims] (1) A consumable electrode type pulsed arc welding method characterized by performing pulsed arc bath welding while periodically varying the peak current value of a welding current having a pulsed waveform. (2) The consumable electrode type pulsed arc welding method according to claim 311, wherein the waveform of the temporary fluctuation of the peak current value indicated by # is a sine wave as a t% sign.