JPS6092077A - Welding method of butted part of pipe - Google Patents

Abstract

PURPOSE:To prevent generation of underbead when butting two pipes at groove width of zero and TIG welding, by providing a ring of specified shape between the pipes and making the ring eccentric to upper part of center line and welding. CONSTITUTION:When butting two pipes 2 and TIG welding at groove width of the butted part zero, a ring 10 is provided between butted parts of the two pipes. The width t of the ring 10 is made nearly equal to the thickness T of the pipes, and the outer diameter is made equal to or slightly larger than outer diameter of the pipes. The ring 10 is made slightly eccentric upward to the center line of the pipes 2, and the two pipes 2 are TIG welded while melting the ring 10. The thickness P of the ring 10 is determined properly basing on the thickness T of the pipes. Molten metal formed by welding is pulled downward by gravity. However, as the ring 10 is deviated upward, underbead is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding method for butt portions of pipes by TIG welding.

In TIG welding, as shown in Fig. 1, an arc is generated between a bare tungsten rod 1 and a workpiece 2 under an atmosphere of inert gas, and the heat is used to weld the filler metal 3 and workpiece 2. This method performs welding while melting the material, and has the advantages of no coating agent or flux furnace, easy welding in all positions, high efficiency, and excellent welding quality, and is widely used for welding metals.

In this TIG welding, as shown in Figure 2, the plate thickness is 1
~ In welding the butt part of 3 holes, the middle of the groove (the middle of the root) is Q.
In some cases, welding is performed with type I welding without the use of filler metal. When the pipe 2 is fixed horizontally as shown in Fig. 2 by welding in the middle of this groove and welded by rotating the TiC rod (as shown in the arrow), as shown in Figs. There is a problem in that the molten metal 4 is pulled downward under the influence of gravity, resulting in underbeads 3 at the final completion.

Therefore, as shown in Fig. 5, it is considered that a ring 5 is placed on the back of the welded part of the pipe 2, and this ring functions as both the conventional backing ring and the insert ring to prevent underbead a. However, as shown by the chain line in the figure, there is a risk that the ring 5 will melt in the upper part and that part will fall down and become an under bead 3.

The object of the present invention is to perform welding without underbeads even in TIG welding in the groove without using filler metal.

In order to achieve this object, the present invention assumes that the molten metal is drawn downward by gravity, and melting is performed slightly above, so that the molten metal protrudes downward while being drawn downward. Next, this invention will be explained in detail based on FIGS. 6 and 7 showing one embodiment of the invention.

As shown in the figure, when two wooden pipes 2, 2 are butted together and the butted portion is TIG welded with groove 1-110, a ring 10 is interposed between the butts of both pipes 2, 2, and this ring The width 1 of ring 10 is approximately the same as the pipe thickness T, and its outer diameter is set to be the same as or slightly larger than the pipe outer diameter, for example, A-0.5ymtr is set to be as large as this ring 1.
0 is slightly eccentrically upward with respect to the center line of the pipe 2, and both pipes 2, 2 are TIC welded while the ring 10 is melted. The thickness P of the ring 10 is appropriately determined based on the thickness T of the pipe 2.

During this welding, the welding is performed while the ring 10 and the abutting portions of both pipes 1 and 2 are melted, and the molten metal is pulled downward by gravity. Protrusion in the outer diameter and lower inner diameter, depression in the lower outer diameter and upper inner diameter are corrected.

Therefore, according to the present invention, by eccentrically moving the ring upward and welding the ring while melting it, underbeads are prevented from occurring and highly accurate welding can be performed.

[Brief explanation of the drawing]

Figures 1 and 2 are front views showing the conventional TIG welding method, Figure 3 is an enlarged cutaway front view of the welded area by the conventional TIG welding method, Figure 4 is a side view of the same, and Figure 5 is a cutaway front view. , 6th
The figure is a front view showing the welding method of the present invention, and FIG. 7 is a sectional view taken along the line X--X in FIG. 6. 1...Tungsten rod, 2...Pipe (object to be welded)
, 3... filler metal, 10... ring.

Claims (1)

[Claims] Two pipes are butted against each other, and the abutting portion is TIed with a groove of 0.
When performing G welding, a ring is inserted between the butts of both pipes, and the width of this ring is approximately the same as the pipe thickness, and its outer diameter is set to be the same as or slightly larger than the pipe outer diameter. A method of welding the butt part of pipes, which is characterized by welding both pipes while melting the ring, slightly eccentrically upward from the center line of the pipe.