JPH08206830A - Penetration welding method - Google Patents

Abstract

PURPOSE: To sufficiently restrain the oxidation of a back bead by welding in a state that a backup member having a groove for storing inert gas faced to bevel parts is in a bridging. CONSTITUTION: The bevel parts 2 of a material to be welded (e.g. large pipe-like member, penstock, large diameter pressure vessel) 1 are butted and the cross sectional U-shaped copper-made backup metal 4 having the groove 3 for storing argon gas (as one sample of inert gas) is welded in the bridging state faced to the bevel parts 2 at the back side of the bevel parts 2 of the materials 1 to be welded. At the time of back-bead welding the bevel parts 2 with a welding torch 5 in this state, the argon gas 7 supplied as the shielding from the welding torch 5 side, is stored into the groove 3 in the backup metal 4, and the argon gas 7 in the groove 3 carries out a function of back shield gas to restrain the oxidation of the back bead 6 formed in the bevel parts 2. By this method, it can be unnecessary to specially supply the back shield gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backside welding method.

[0002]

2. Description of the Prior Art In conventional backside welding in TIG welding, as shown in FIG. 2, a cover 32 is arranged on the back side of a groove portion 31 of an object to be welded 30, and a supply pipe 33 is attached to the cover 32. For example, 2 to 4 l / min of argon gas is supplied from the supply pipe 33 into the cover 32 for back shield, and 2 for shield from the welding torch side.
An argon gas atmosphere is created in the groove 31 by supplying 5 l / min of argon gas to prevent the back bead 34 from being oxidized.

[0003]

The above-mentioned conventional welding method has a problem that it is uneconomical because the argon gas for the back shield is supplied separately from the argon gas for the shield.

Therefore, an object of the present invention is to provide a backside welding method capable of solving the above problems.

[0005]

Means for solving the problems of the present invention are as follows. The groove portions of the objects to be welded are abutted against each other, and the groove portions of the objects to be welded are opposite to each other. The backing member having a groove for accumulating an inert gas is welded in a state of being extended.

[0006]

In the above means for solving the problems, when the groove portions are abutted to each other and the backing member having the groove for retaining the inert gas is welded to the back side of the groove portions of the objects to be welded, welding is performed. The inert gas supplied from the welding torch side for shielding collects in the groove of the backing metal, and the inert gas in this groove functions as a back shield gas, oxidizing the back bead formed in the groove. Suppress.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1, which is a backside welding method in TIG welding, in which an object to be welded (for example, a large-diameter pipe-shaped member, a hydraulic iron pipe, Diameter pressure vessel) 1 groove portions 2 are butted against each other, and a groove 3 for accumulating argon gas (an example of an inert gas) facing the groove portion 2 is provided on the back side of the groove portions 2 of the objects 1 to be welded.
Welding is performed with the copper backing metal 4 having a U-shaped cross-section having a cross section.

In this state, when the groove portion 2 is backside welded by the welding torch 5, the argon gas 7 supplied for shielding from the welding torch 5 side is collected in the groove 3 of the backing metal 4, and the inside of this groove 3 is filled. The argon gas 7 functions as a back shield gas, and it is possible to suppress the oxidation of the back bead 6 formed in the groove 2.

Further, by bringing the backing metal 4 made of copper into contact with the object to be welded 1, the heat of the contacting part of the object to be welded 1 with the backing metal 4 escapes to the side of the backing metal 4 and is cooled. So it can be welded with a larger current than before, and therefore
It is possible to increase the amount of the deposited metal that is welded to the groove portion 2, so that sound and stable welding can be performed.

As described above, when the groove portions 2 of the object to be welded 1 are backside welded, the copper backing plate 4 having the groove 3 for accumulating the argon gas is transferred to the rear side of the groove portion 2. By welding in this state, the argon gas supplied from the welding torch 5 side collects in the groove 3 of the backing metal 4, so back shield gas is not required and it is economical, and the back bead 6 is oxidized. In addition, since the contact portion of the work piece 1 with the backing metal 4 is cooled, the temperature of the groove portion 2 rises abnormally even if welding is performed with a larger current than in the past. It is possible to increase the amount of the deposited metal for each pass, and to perform sound and stable welding.

[0011]

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, when the groove portions are abutted against each other, the inert gas pools facing the groove portions are provided behind the groove portions of the objects to be welded. Since the backing member having the groove is welded across, the inert gas supplied from the welding torch side collects in the groove of the backing metal and functions as a back shield gas. It is economical because there is no need to supply a back shield gas, and oxidation of the back bead can be sufficiently suppressed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a welded portion constructed by a welding method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a welded portion constructed by a conventional welding method.

[Explanation of symbols]

 1 Workpiece 2 Groove 3 Backing metal groove 4 Backing metal 5 Welding torch 6 Back bead 7 Argon gas

Claims (1)

[Claims] 1. The groove portions of the objects to be welded are butted against each other, and a backing member having a groove for holding an inert gas facing the groove portions is provided behind the groove portions of the objects to be welded. A backside welding method characterized by welding in a state.