JPS61266185A - Double electrode mig welding method - Google Patents

Abstract

PURPOSE:To increase an operational efficiency and to equalize the welding quality by setting the current and voltage of the succeeding electrode higher than the preceding electrode and by melting constantly always the molten metal of the preceding electrode by the succeeding electrode. CONSTITUTION:The succeeding electrode 3 is arranged on the opposite side to the preceding electrode 2 and current and voltage thereof are set higher than those of the preceding electrode 2. The root face beta inside the groove 11 which could not be melted by the preceding electrode 2 and the molten metal are melted and further the metal melted by the preceding electrode 2 is melted constantly always corresponding to the variation in the root face beta and root gap alpha. With this method, the work of back chipping, etc. is disused and a complete butt is obtd. as well. the operational efficiency in welding is therefore increased and at the same time the welding quality is equalized.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to two-electrode MAG (MIG) welding, and in particular,
This invention relates to a two-electrode MAG welding method that allows complete penetration in butt welding without the need for processing such as back chiseling.

[Background of the invention]

In MAG welding, a wire with a small diameter of 1.2 mmφ-1.6+++ mφ is usually used, so the current density is relatively high, and therefore deep penetration can be achieved. When performing X-shaped butt welding of thick plates by this MAG welding, FIG. 3 shows a general lamination method. The welding procedure is such that after the grooves of the base metals 1 are aligned, they are first laminated. In this welding method, poor penetration 10 occurs due to changes in root spacing α and root surface β, and complete penetration cannot be achieved at 100%.

The above welding method is not suitable for welding pressure vessels and other items that require complete penetration. As a countermeasure for this,
This is commonly done, but after welding one side, the unwelded part of the opposite side is welded. This is the so-called Urahatsuri method. The back chisel method is as shown in Figure 4, after welding one side, as shown in Figure 5,
The part 21 on the back side that does not melt is removed by cowling, a grinder, etc., and then as shown in Figure 6,
weld and obtain a complete welded joint. However, this butt welding method using a back-end pick not only requires the extra work of back-end pick-up, but also requires finishing work with a grinder, which has been an impediment to improving workability.

The content of is shown in FIG. 7, where there is a trailing electrode 3 with an inter-electrode distance of 8 from the leading electrode 2, and by setting the trailing electrode 3 to be shifted by a distance of 22 in the transverse direction with respect to the advancing direction, the electrode 3 is formed with the leading electrode 2. The molten metal 9 that has been removed is remelted by the trailing electrode 3 to form a new molten metal 10, but this method is applicable only within the same groove and is not applicable to the first layer. However, defects due to poor penetration cannot be eliminated.

[Purpose of the invention]

The purpose of the present invention is to provide two electrodes placed on both sides of the
To develop welding by welding from both sides, freely controlling the penetration depth, constantly adapting the welding conditions to the root width of the welding groove to obtain a perfect butt weld, and further improving workability. The object of the present invention is to provide a two-electrode MAG welding method for the purpose of.

[Summary of the invention]

The present invention enables butt welding, which requires complete penetration without internal defects, without the need for back chisel work, etc.
This has achieved the purpose of making it possible to obtain complete penetration.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is an explanatory diagram showing the arrangement of two electrodes within a welding site. In the figure, reference numeral 2 denotes a leading electrode, which is located within the groove 11- and is placed as a reference in a welding direction that is set according to a groove angle (not shown). 3 is a trailing electrode. This trailing electrode 3 is disposed on the opposite side of the leading electrode 2, and during welding, the current and voltage are set higher than that of the leading electrode 3, and the groove 11, which cannot be melted by the leading electrode 3, has a rut surface β. In addition, the metal melted by the preceding electrode 2 is constantly melted in a constant manner in response to changes in the root surface β and the root gap α in the groove 11. Although this example does not describe the inclination angle of the leading electrode 2 and trailing electrode 3 in the welding direction,
The angle can be set arbitrarily depending on the welding current and voltage or welding speed. FIG. 2 shows a sectional view taken along the line XX in FIG. 1.

An arc 4 is generated at the leading electrode 2 using a certain fixed welding current and voltage to form a molten metal 9. The penetration depth of the preceding electrode 2 into the base material 1 at this time is 5. Trailing electrode 3
of the molten metal 9 formed by the preceding electrode 2,
A part of the molten metal is located on the opposite side of the range where solidification begins (distance between the leading electrode 2 and the trailing electrode 8), and the current and voltage are set higher than the leading electrode 2 to generate an arc 4 and molten metal 1.
form 0. The penetration depth of this trailing electrode 3 is 6, and by controlling the welding conditions so that the lap portion 7 with respect to the penetration depth 5 of the preceding electrode is constant, the penetration depth is always 6 during the welding groove. The welding work can be carried out extremely easily, workability is greatly improved, and excellent effects such as no internal defects such as poor penetration can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, high-level welding such as underside welding can be automated, and the effect is great.

[Brief explanation of drawings]

Fig. 1 is a diagram of the arrangement of electrodes during implementation of the two-electrode MIG welding method of the present invention, Fig. 2 is a sectional view taken along line XX in Fig. 1, and Fig. 3 is a
Cross-sectional explanatory diagrams of defective parts due to normal poor penetration, Figures 4 and 5
6 and 6 are respectively explanatory diagrams of work performed by normal back chiseling, and FIG. 7 is an explanatory diagram of a known two-electrode MIG welding method. 1. Base material, 2. Leading electrode, 3. Trailing electrode, 4.
...Arc, 5...Penetration, 6...Penetration, 7...
Wrap portion of melting.

Claims (1)

[Claims] 1. In two-electrode MIG welding in which the leading and trailing electrodes have the same polarity, the leading electrode is placed at a reference position within the groove of the base material to be welded, and a portion of the molten metal caused by the leading electrode solidifies. Within the starting range, the trailing electrode was placed on the opposite side of the groove of the leading electrode, and during welding, the current and voltage of the trailing electrode were set higher than those of the leading electrode, so that the leading electrode could not melt. A two-electrode MIG welding method, characterized in that the root surface of the groove and the molten metal are melted by a trailing electrode, and the metal melted by the leading electrode is always melted at a constant rate, making it possible to perform complete butt welding. .