JPH0669638B2 - One-sided welding backing material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a backing material for one-sided welding, which is pressed against the back surface of a material to be welded to form a back bead during one-sided welding.

[Prior art]

The conventional backing method in single-sided welding is, as shown in the side cross section of FIG. 5, a backing material 2 such as flux or glass fiber tape along a groove line on the back surface of the material to be welded 1 and a backing copper plate 4
By pressing, welding electrode (wire) 3 and welded material 1
The material to be welded 1 is welded by generating an arc between and.

The backing material 2 in the prior art serves to melt and become slag during welding to perform metallurgical protection of the back bead.

Further, the backing copper plate 4 which is the backing metal plays a role of promoting solidification by heat dissipation of the melting portion due to good thermal conductivity.

[Problems to be solved by the invention]

However, the groove gap may change due to poor processing accuracy of the material to be welded, and in that case, there is a problem that the back bead becomes uneven by the conventional backing method alone.

With respect to this problem, the present inventor has proposed that the welded material 1 and the backing copper plate 4
It is found that the voltage value generated between and is related to the shape of the back bead, and the welding current value is controlled by detecting the voltage and comparing it with a reference voltage so that the back bead width is always constant. Thought. However, in this case, if the back bead comes into direct contact with the backing copper plate 4 even once due to some influence, a short circuit occurs at that portion, and thereafter, the above-mentioned detection voltage cannot be detected at all.

It should be noted that Japanese Patent Publication No. Sho 50-36822 discloses a back bead detection element in which a plurality of back bead detection elements are embedded at equal intervals in the groove gap width direction in a consumable backing material such as solid flux and contacted with the back bead. Although a method of detecting the width of the back bead from the number of the back beads has been proposed, this backing material has a drawback that the structure becomes complicated and costly, and the detection electrode melts into the back bead and impairs the appearance. .

The present invention is for solving the above-mentioned problems,
It is an object of the present invention to provide a backing material for single-sided welding which can be used to control the width of the back bead, as well as being able to form a good back bead.

[Means for solving problems]

The present invention aims to provide a backing material for single-sided welding, in which a good bead is formed in order to solve the above-mentioned problems of the prior art, and the width of the back bead can be controlled. In welding, in a backing material of an inorganic material that is pressed against the back surface of the material to be welded along the groove, a wire mesh of the same material as the material to be welded is arranged in the center of the backing material and over the entire length, and the wire mesh A backing material for single-sided welding, in which the inorganic material is electrically insulated from the material to be welded and the backing metal, and the voltage between the material to be welded and the wire mesh can be detected. .

Further, the inorganic material in the backing material for one-sided welding is composed of granular or solid flux, or the inorganic material is composed of tape-shaped glass fiber or a combination thereof.

[Action]

Since the present invention is a backing material for one-sided welding having the above-described configuration, when performing one-sided welding of a material to be welded using this, as shown in Examples described later, the material to be welded and the end portion of the wire mesh are If the arc plasma hits the inorganic material through the gap between the materials to be welded by connecting the wires in advance with a conductive wire, a voltage will be applied between the wire mesh covered with the inorganic material and the material to be welded. Occurs. The inorganic material in the portion hit by the arc is melted, and the wire mesh in that portion is also melted to form a weld bead after solidification. Although arc welding progresses toward the end of the wire mesh in the longitudinal direction, since the wire mesh is covered with an inorganic material, the wire mesh in the backing material does not come into direct contact with the material to be welded, and since the wire mesh melts sequentially, the back bead is directly welded. Since there is no contact with the wire, the voltage between the material to be welded and the wire mesh can be detected to the end without a short circuit. Therefore, the uniform back bead width can be easily formed by controlling the welding current value using the voltage generated between the material to be welded and the wire mesh.

Even if the back bead comes into direct contact with the backing copper plate, the voltage between the material to be welded and the wire mesh can be measured, so that the back bead width can be controlled without any influence.

〔Example〕

The present invention will be described in detail with reference to Examples. FIG. 1 is a side sectional view in which single-sided welding is performed using a backing material which is an embodiment of the present invention.

In FIG. 1, 1 is a material to be welded, 2 is a backing material made of an inorganic material such as flux or glass fiber, 3 is a welding electrode (welding wire), 4 is a backing copper plate which is a backing metal, and 5 is a book It is a tape-shaped wire mesh according to the invention. Since the metal net 5 is covered with the inorganic backing material 2 as shown in the drawing, it is electrically insulated from the welded material 1 and the backing copper plate 4.

The metal net 5 is embedded in the backing material 2 and provided for the welding length as shown in the figure. The portion which is melted by the welding arc and then solidified becomes a part of the back bead 6.

Next, FIG. 2 (A) is a plan view showing the backing material 2 of the present invention, and FIG. 2 (B) is a side view. As shown in FIGS. 2 (a) and 2 (b), a tape-shaped wire mesh 5 is covered with the backing material 2 at the center of the backing material 2, and a backing copper plate is provided on the back surface of the material 1 to be welded. When it is crimped by 4, the wire mesh 5 and the work piece 1 are not in direct contact with each other and are electrically insulated from each other. The voltage generated between the wire mesh 5 and the wire net 5 can be detected.

Next, regarding the backing method using a glass fiber tape and a copper plate, an example of using a backing material in which a wire mesh with a diameter of 0.23 mm and 50 mesh × 5 mm width is inserted into the third piece of glass fiber tape (13 pieces stacked) Describe.

In this case, the voltage between the material 1 to be welded and the wire mesh 5 was detected by the voltage between the wire mesh 5 on the welding end side and the material 1 to be welded.

Next, the material 1 to be welded had a V-shaped groove with a plate thickness of 12 mm and 50 °, and the backing material 2 was pressure-bonded to the back surface of the groove. At this time, the wire mesh 5 was arranged so as to be aligned with the groove line.

FIG. 3 is a graph showing the relationship between the back bead width (mm) and the detection voltage (V) when welding is performed by changing the preceding welding current using two-electrode submerged arc welding (SAW). Is.

As shown in FIG. 3, the relationship between the detection voltage generated between the material to be welded 1 and the wire net 5 and the back bead width when performing single-sided welding shows a very good correlation.

FIG. 4 shows the welding current and detection voltage when automatic back bead control is performed by changing the welding current so that the detection voltage becomes 1.5 V under the welding conditions shown below using the backing material of the present invention. 2 is a waveform chart diagram of FIG.

Welding conditions: Leading electrode Welding current 750 to 950A, Welding voltage 35V Trailing electrode Welding current 500A Welding voltage 36V Welding speed 50cm / min As shown in Fig. 4, there is a very good correlation between welding current and detection voltage. Therefore, it is clear that if the welding current is controlled by using the voltage signal generated between the material to be welded 1 and the wire net 5, the back bead width can be automatically controlled easily.

The material of the backing material 2 may be a granular or solid flux, or two layers of a glass fiber tape and a solid flux other than the glass fiber tape. In short, the wire mesh 5 may be electrically insulated.

〔The invention's effect〕

According to the present invention, not only the back bead having a good appearance can be formed, but also the voltage between the material to be welded and the wire mesh can be accurately detected. Therefore, it is preferable to control the welding current by using the voltage value. It is a backing material for single-sided welding, which has a simple structure and is inexpensive, and has an extremely large effect industrially.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention. FIG. 2 (A) is a plan view of the backing material for single-sided welding according to the present invention. FIG. 2B is a side view of the backing material for single-sided welding according to the present invention. FIG. 3 is a graph showing the relationship between the back bead width and the detection voltage according to the present invention. FIG. 4 is a waveform chart showing the relationship between the welding current and the detected voltage when the back bead automatic control according to the present invention is performed. FIG. 5 is a side sectional view in the case of using a conventional backing material for single-sided welding. In the figure, 1: material to be welded, 2: backing material, 3: welding electrode, 4: backing copper plate, 5: wire mesh, 6: back bead

Claims (3)

[Claims] 1. A backing material made of an inorganic material, which is pressed against a back surface of a material to be welded along a groove in single-sided welding, and a wire mesh made of the same material as the material to be welded at the center and the entire length of the backing material. Is arranged, and the wire mesh is electrically insulated from the material to be welded and the backing metal with the inorganic material so that the voltage between the material to be welded and the wire mesh can be detected. Backing material for single-sided welding. 2. The backing material for one-sided welding according to claim 1, wherein the inorganic material is a granular or solid flux. 3. The backing material for one-sided welding according to claim 1, wherein the inorganic material is a glass fiber in a tape shape.