JPS6224181B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of butt welding tube bodies, and more particularly to a method of welding by fitting a backing ring across both ends of the tube body.

For example, in piling work for steel pipe piles, a lower pile 1 and an upper pile 2 are sometimes butt-welded on site as shown in FIG. In that case, by fitting the backing ring 3 to the inner circumference of the upper end 1a of the lower pile 1 and the lower end 2a of the upper pile to be welded together, it is possible to prevent molten metal from flowing into the inside of the pile during welding. At the same time, the lower pile 1 and the upper pile 2 are held on the same axis. By the way, conventionally, as shown in FIG. 1, a backing ring 3 having a plurality of protrusions 4 integrally protruding from its outer periphery is used, and the lower half of this backing ring 3 is attached to the upper end 1a of the lower pile 1. The projections 4 are brought into contact with the upper end surface of the lower stake 1 to support this backing ring 3 on the lower stake 1, and then the lower end 2a of the upper stake 2 is placed on the top of the backing ring 3. The half part was fitted until the lower end surface came into contact with the protrusion 4, and then the upper end part 1a of the lower pile and the lower end part 2a of the upper pile were manually welded. However, in this method, the protrusion 4 has poor penetration during welding, and the welding of the protrusion 4 portion is incomplete. Therefore, when a horizontal force is applied to the pile, the welding cannot be performed on the protrusion 4.
There was a risk that the parts would be damaged. Although there were still ways to deal with such problems in the case of manual welding, apart from the problem of work efficiency, it has become an unavoidable problem when applying automatic or semi-automatic welding.

In addition, in the backing ring 3 shown in FIG.
Since it is formed from a cut-and-raised piece, it has an opening 4a corresponding to the projection 4. Therefore, there is a risk that molten metal may flow down from this opening 4a,
There are also problems such as the heat capacity changing at the opening 4a and the welding conditions changing.

An object of the present invention is to provide a welding method that allows easy support of a backing ring and is free from the risk of welding defects.One embodiment of the present invention will be described below with reference to FIGS. 2 to 4.

First, as shown in FIG. 2, the backing ring 5 is fitted onto the inner periphery of the upper end portion 1a of the lower pile 1 and supported. That is,
The backing ring 5 includes a ring body 6 having an arcuate cross section and a dividing portion 7 at one location in the circumferential direction, and a central portion in the axial direction that is spaced apart in the circumferential direction on the outer periphery of the ring body 6;
That is, the ring body 6 is provided with a plate-shaped or rod-shaped support fitting 8 which is attached to the maximum outer diameter position of the ring body 6 by welding 9 only on one side in the axial direction. Further, the edges of the divided portion 7 are separated from each other, and a backing plate 10 is provided on the back surface of the divided portion, and one end in the circumferential direction is welded.
With the weld 9 facing upward, the lower half of this backing ring 5 in the axial direction is fitted onto the inner circumference of the upper end 1a of the lower pile 1, and is pushed in until the support metal fitting 8 comes into contact with the upper end surface 1b of the lower pile. . Then, the backing ring 5 is tightly fitted to the upper end portion 1a of the lower stake, and is securely supported by the lower stake 1 by the support fitting 8. Next, as shown in FIG. 3, root spacing holding beads 11a to 11d are formed between each support fitting 8 on the upper end surface 1b of the lower pile, integrally with the backing ring 5. These root spacing maintaining beads are sequentially formed starting from the bead 11a adjacent to the dividing portion 7, beads 11b and 11c, and finally a bead 11d aligned with the dividing portion 7.
In this way, these root spacing beads 11a to 11
When the backing ring 5 is supported by d, the supporting metal fitting 8 is cut and removed using a gas torch or the like. After gas cutting, inspect whether there are any protrusions on the surface of the backing ring 5, that is, the ring body 6, and if any, remove them with a grinder to make them smooth, remove the slag from the root spacing beads 11a to 11d, and adjust the height of the protrusions. Use a grinder to adjust the temperature to within the specified value. Thereafter, as shown in FIG. 4, the upper pile 2 is erected, and its lower end 2a is fitted into the upper half of the backing ring 5. Then, the lower pile 1 and the upper pile 2 are held concentrically through the backing ring 5, and there is a root spacing holding bead 11 between the lower pile upper end surface 1b and the upper pile lower end surface 2b.
A predetermined route interval is maintained by a to 11d. In this way, by welding the upper end 1a of the lower pile 1 and the lower end 2a of the upper pile 2 using a semi-automatic welding machine (not shown), the lower pile 1 and the upper pile 2 can be welded together without any welding defects. are joined.

FIG. 5 shows another embodiment of the backing ring. This backing ring 15 is formed so that the ring body 16 has a circumference considerably longer than the inner circumference of the lower pile 1, and one end 16a and the other end 16b overlap each other in the radial direction, as shown by the imaginary line. The dividing part 7 and the backing plate 10 are eliminated. This backing ring 15
When using the root spacing bead 1, after tightly fitting the backing ring 15 to the upper end 1a of the lower pile.
1a, 11b, and 11c are formed, and then the other end 16b of the ring body 16 is cut and removed at the overlapping part of the one end 16a and the other end 16b, and the ring body 16 is separated by a gap between its edges. After fitting the ring body 16 to the upper end portion 1a of the lower pile without
The root spacing bead 11 spans between the edges of the
form d. Other steps are similar to the embodiments shown in FIGS. 2 to 4.

In the above explanation, only the connection of the lower pile and the upper pile in the pile driving work of steel pipe piles has been explained, but it is clear that the present invention can also be applied to butt welding of columns and other various pipe bodies.

According to the method of the present invention, as explained above, a root spacing bead is formed with the backing ring temporarily supported at one end of the tube using the backing ring having the support metal fitting, and the support metal fitting is After cutting and removing, the other end of the tube is fitted into the backing ring and both tubes are welded together, so there is no need for effort to attach and support the backing ring, and it is easy to weld both tubes together. Since there are no dissimilar metals in the weld, sufficient penetration can be achieved and a welding defect-free joint can be achieved.

[Brief explanation of the drawing]

Fig. 1 shows a conventional example, a is a plan view, b is a vertical sectional view taken in the direction of a - Figs. Fig. 3B is a plan view of a state in which the backing ring is fitted; FIG. FIG. 4 is a vertical sectional view showing the state in which the upper pile is installed, and FIG. 5 is FIG. 3a showing another embodiment of the present invention.
FIG. 1... Lower pile (one tube body), 1a... Upper end, 1b
...Top end surface, 2...Top pile (other pipe body), 2a...Lower end portion, 2b...Lower end surface, 5, 15...Backing ring, 6,
16...Ring body, 7...Divided part, 8...Support fitting, 9
... Welding, 10... Backing plate, 11a to 11d... Root spacing holding bead.

Claims (1)

[Claims] 1. The lower half of the backing ring, in which a plurality of supporting metal fittings are attached at intervals in the circumferential direction at the center in the axial direction of the outer periphery, is attached to one tube end, and the plurality of supporting metal fittings are attached to the one tube end. After fitting so as to be in contact with the end surface of the tube body, and then forming a root spacing bead integrally with the backing ring on the end surface of the one tube body,
A method for butt welding a tube body, comprising cutting and removing the supporting metal fitting, then fitting the other tube end portion into the upper half of the backing ring, and welding the ends of both tube bodies.