JPS632594A - Backing fixing method for butt welding - Google Patents

Abstract

PURPOSE:To prevent the bucking of a backing based on a thermal expansion and perform the welding in good state by closely fitting a backing to the plate to be welded after applying the tensile strength in the weld line direction thereon in the butt welding using a backing. CONSTITUTION:The backing 1' providing projections 1'a and 1'b at the intervals of the welding length or more is abutted to the steel plates (a), (b) to be subjected to a butt welding. The projection 1'a is abutted to the end face of the steel plates (a), (b), a tension is applied on the backing 1' by the hydraulic jack 5 whose one end is abutted to the fitting 4 which is fixed respectively to the steel plates (a), (b) via a force receiving plate 1'c on the projection 1'b of the other end, and after giving the necessary tension the backing 1 is fixed by a wedge 3 and fixing fitting 2. In this way, the compression force caused on the backing by the thermal expansion is reduced or eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a backing fixing method applied to butt welding of steel plates, etc.

[Conventional technology]

Conventionally, as shown in Figs. 3 to 5, a copper backing 1 was placed under the weld line of the steel plates a and b to be butt welded, and a wedge 3 was attached to the fixing bracket 2 that fixed the steel plates a and b. Drive it in and fix it. In such a fixing method, the steel plate a is fixed by heat input through welding.

When b and the backing 1 become hot, the copper backing 1 expands more because they have different coefficients of linear expansion.

In addition, since the related cross-sectional area of the backing 1 is significantly smaller than that of the backing 1, the backing 1 buckles between the fixed points and separates from the steel plates a and b, as shown in FIG.

As a result, the weld metal did not form the desired shape in the distant parts of the backing 1, which was likely to cause welding defects.

[Problem that the invention seeks to solve]

As mentioned above, measures to prevent buckling due to expansion of the backing include narrowing the installation interval of fixing metal fittings, or having one worker constantly monitor the welding process and constantly tightening the wedges. However, both were economically disadvantageous, and improvements were needed.

[Failure to solve the problem]

In order to solve the above problems, the present invention is a backing fixing method in which, prior to fixing the backing, a large tension is applied in the longitudinal direction of the backing on the condition that the backing does not yield.

That is, in butt welding using a backing, a method for fixing a backing for butt welding is provided, which is characterized by applying a tensile force to the backing in the welding line direction and then bringing the backing into close contact with a plate to be welded.

[Effect]

The butt welding backing fixing method of the present invention is as described above, so by applying tension in the longitudinal direction to the backing, the compressive force generated on the backing due to thermal expansion can be reduced. Alternatively, since it can be erased, this method can significantly reduce the probability of buckling of the backing.

〔Example〕

Hereinafter, two embodiments of the present invention will be specifically described based on embodiments shown in the drawings. FIG. 1 is a front view to which a butt welding backing fixing method according to an embodiment of the present invention is applied. FIG. 2 is a plan view of FIG. 1 according to this embodiment. The explanation will be given below. 1st
．． In Figure 2, a backing 1 is provided with protrusions 1/a and 1'b at intervals equal to or longer than the welding length on steel plates a and b to be butt welded.
', and the protrusion 1/a is applied to the end surfaces of the steel plates a and b, and the protrusion 1'b at the other end is placed through the force receiving plate 1'C.

Tension is applied to the backing 1' by a hydraulic jack 5 with one end placed against a metal fitting 4 fixed to each of steel plates a and b, and after the required tension is applied, the backing 1 is fixed using a wedge 3 and a fixing metal fitting 2. . In this example.

The reaction force of the tension of the backing l is applied to the steel plate a to be welded.

Although the reaction force is applied to steel plate b, the same effect can be achieved even if the reaction force is applied to a location independent of steel plates a and b.

〔Effect of the invention〕

As specifically explained above, in the present invention, buckling of the backing due to thermal expansion due to welding is prevented.

This can be prevented by applying tension before fixing the backing, and therefore welding can be performed in good condition, and the effect is remarkable.

[Brief explanation of drawings]

Fig. 1 is a front view to which a butt welding backing fixing method according to an embodiment of the present invention is applied, Fig. 2 is a plan view of Fig. 1 according to this embodiment, and Fig. 3 is a conventional butt welding method. FIG. 4 is a front view showing the backing fixing method, FIG. 4 is a side view of the conventional method shown in FIG. 3, and FIG. 5 is a front view showing the welded state using the conventional butt welding backing fixing method. . 1.1'--Backing 1'a, 1'b,...Protrusion
1/c,... force receiving plate, 2... fixing metal fittings, 3... wedge, 4
...Metal fittings, 5...Hydraulic jack.

Claims (1)

[Claims] A method for fixing a backing for butt welding, which involves applying a tensile force to the backing in the direction of the welding line and then bringing the backing into close contact with a plate to be welded.