JPS6277199A - Backing material for one-side welding - Google Patents

Abstract

PURPOSE:To obtain penetration beads having good external appearance without bringing a molten metal and a copper plate into contact with each other, by providing at least two layers of backing materials of an inorganic substance, which are pressed against the reverse side of a groove part by the copper plate, and forming the backing material of the lower layer by using a material whose melting point is higher than that of the backing material of the upper layer. CONSTITUTION:One-side welding is executed by pressing a backing material 5 of an inorganic substance along the reverse side of a groove part of a material to be welded 1 by a backing copper plate 4, and generating arcs between a welding electrode 3 and the material to be welded 1. In this case, as for the backing material 5 to be used, at least two layers are used, and a backing material 5B of the lower layer is formed by a material whose melting point is higher than that of a backing material 5A of the upper layer. In this regard, the backing material 5 is constituted of a granular or solid flux, or a glass fiber tape. In this way, a molten metal and the copper plate do not come into contact with each other, and penetration beans having good external appearance can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a backing material that is pressed against the back surface of a workpiece during single-sided welding.

[Prior art and its problems]

In single-sided welding, as shown in Fig. 3, a backing material 2 such as flux or glass fiber tape is pressed against the back surface of the workpiece 1 along the groove using a backing copper plate 4, and the welding electrode 3 and workpiece are welded together. The material 1 to be welded is welded by generating an arc between the material 1 and the material 1.

The backing material 2 melts during welding, becomes slag, and serves to protect the back bead.

However, if the backing plate 2 is made of a material with a low melting point, the backing bead will directly contact the backing copper plate 4, which will cause copper to get mixed into the weld bead and cause welding defects. Further, since this portion is not protected by the slag caused by the γ contact material 2 in which the back bead is melted, a problem arises in that the bead appearance is not clear.

In addition, it has recently been found that the voltage generated between the material to be welded 1 and the backing copper plate 4 is related to the shape of the backing bead. However, there was a problem in that the molten metal directly contacted the backing copper plate, and therefore the voltage could not be detected.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a backing material that can not only form a good back bead but also prevent the back bead from directly contacting the backing copper plate.

[Summary of the invention]

During single-sided welding, an inorganic backing material is pressed against the back surface of the material to be welded by a backing copper plate along the groove, and the backing material has at least two layers, and the lower layer of the backing material is the same as the upper layer of the backing material. It is characterized by being made of a material that has a higher melting point than the other materials.

[Structure of the invention]

Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing a state in which one-sided welding is performed using a true member according to an embodiment of the present invention.

As shown in FIG. 1, a backing material 5 according to an embodiment of the present invention
has two layers: an upper layer tape 5A that is directly pressed against the back surface of the workpiece 1 along the groove, and an upper layer tape 5
It consists of a lower layer tape 5B bonded to the lower surface of A.

The upper layer tape 5A is made of glass fiber tape with a low melting point of 900° C. or lower. The lower layer tape 5B is made of a glass fiber tape having a high melting point of 1200° C. or higher.

In this way, when single-sided welding is performed with the backing material 5 made of two layers, a low melting point tape and a high melting point tape, the low melting point upper layer tape 5A that is directly pressed against the back surface of the welded material 1 , melts quickly to form a slag, high melting point lower layer tape 5
In B, since the back bead hardly ever melts, the back bead does not come into direct contact with the backing copper plate 4, and as a result, the back bead has a clean appearance. As is clear from FIG. 2, when the backing material of the present invention is used, the voltage changes more significantly than when the conventional backing material is used.

Therefore, the welding current can be easily controlled using the voltage generated between the material to be welded 1 and the backing copper plate 4, so that the back bead width can be automatically controlled more easily. The backing material 5 may be made of granular or solid flux in addition to glass fiber tape, and the backing material 5 should have at least two layers, but at least the bottom layer of the backing material may be glass fiber tape or solid flux. Any solid flux is fine.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible not only to form a good back bead, but also to prevent the back bead from directly hitting the backing copper plate, and to prevent the back bead from directly hitting the backing copper plate. This brings about the extremely useful effect of being able to stably detect voltage.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a state in which one-sided welding is performed using a backing material according to an embodiment of the present invention, FIG. 2 is a graph showing the relationship between detected voltage and welding current, and FIG. 3 is a graph showing the relationship between detected voltage and welding current. FIG. 2 is a cross-sectional view showing a state in which one-sided welding is performed using a conventional backing material. In the drawings, 1... Material to be welded, 2... Backing material, 3... Welding electrode, 4... Backing copper plate, 5... Backing material,
5A... Upper layer tape, 5B... Lower layer tape.

Claims (5)

[Claims] (1) In an inorganic backing material that is pressed against the back side of the workpiece by a backing copper plate along the groove during single-sided welding, the backing material is made of at least two layers, and the backing material of the lower layer is is a backing material for single-sided welding characterized by being made of a material with a higher melting point than the upper layer backing material. (2) The backing material for single-sided welding according to claim 1, wherein the backing material is granular or solid flux. (3) The backing material for single-sided welding according to claim (1), wherein the backing material is a glass fiber tape. (4) The backing material for single-sided welding according to claim 1, wherein the bottom layer of the backing material is solid flux. (5) Claim No. 1 (1) characterized in that the lowermost backing material of the backing material is a glass fiber tape.
) Backing material for single-sided welding as described in item.