JPH01233014A - Steel pipe with inside ribs and its manufacture - Google Patents

Abstract

PURPOSE:To stabilize quality, to simplify a manufacturing stage and to reduce manufacturing cost by inserting and fixing a sleeve obtained when a thin plate having preformed projections is formed in a cylindrical shape to the tip or the overall length of a steel pipe. CONSTITUTION:When the thin plate 3 is wound in a round shape, the projections which form desired helical ribs 2a are formed by pressing in advance on the thin plate 3. The thin plate 3 having projections 2a formed in this way is formed in a round shape to obtain a sleeve 2. It is possible to work the sleeve 2 easily on the thin plate 3 by providing slits 4 on the projection 2a at a prescribe interval. The sleeve 2 obtained in this way is inserted into the steel pipe 1. The product can be manufactured economically by this method.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" This invention relates to a novel steel pipe with internal ribs and a method for manufacturing the steel pipe.

``Prior art'' Assuming that a spiral protrusion made of a round or square bar is installed around the inner periphery of the tip of an open-ended steel pipe pile, it is possible to prevent the soil from resisting the drag force without disturbing the topsoil on the inner wall of the pile during normal rotation. A drilled steel pipe pile that promotes penetration, increases penetration speed, increases inner circumferential surface friction resistance, and exhibits a large tip support force was proposed by the applicant in Japanese Patent Application No. 1986-286855. It has been proposed in No. 62-302492, etc.

On the other hand, steel pipes with ribs for studs attached to the entire length of the inner surface of the pipe wall are used as synthetic steel pipes that are used as jacket pipes for mortar-lined steel pipes.

Now, as described in Section 2, as a means of forming spiral ribs made of round or square bar steel over the entire length or part of the inner surface of a steel pipe, it was initially possible to form ribs on the inner surface of the pipe wall of a ready-made steel pipe. The process used to be welded, but when carrying out this process, it was difficult to install the ribs because it required a great deal of time and effort, such as marking inside the pipe, carrying the rib material into the pipe, tacking, and welding. The workability is very poor (particularly impossible for small diameter pipes), the cost is high, and it is difficult to correctly attach the ribs in the specified state. For example, there is an automatic mechanized means that can be welded to a steel plate, roll-bended, rolled into a plate, and formed with internal ribs at the same time as the pipe, and is also possible for small-diameter pipes, for example, in Japanese Utility Model Publication No. 53-24092. This method has been proposed in Japanese Patent Publication No. 51-107262, etc.

[Problem to be solved by the invention] However, the automatic mechanization of the ridge is a technology for cases where the inner spiral rib extends over the entire length of the steel pipe, and it has the difficult problem of forming a steel plate where the cross-sectional strength locally changes dramatically. In addition, it is extremely uneconomical to deal with the case where the inner spiral rib is formed only at the tip of the drilled steel pipe pile mentioned above, and new problems are involved, and it is difficult to put it into practical use. There is a problem in that it is not easy to solve the problem, and furthermore, there is a disadvantage that a process for forming ribs on the steel plate must be inserted into the existing pipe-making line.

For example, even if the above-mentioned model with internal ribs only for the tip is cut into parts and connected to the tip of the raw pipe, it will take a lot of man-hours, and there are concerns about the strength of the welded part. becomes.

In addition, other problems include the need for narrow plates for fine spiral protrusion pitches, which requires a large amount of welding, and the complexity of equipment when creating a production line that accommodates various spiral protrusion pitches. be.

In consideration of the ridges, the present invention forms ribs on the inner surface of the wall of a ready-made steel pipe by post-processing, and even for small diameter pipes,
It is an object of the present invention to provide a steel pipe with internal ribs, which can form internal ribs extremely simply and economically, even if the entire length or a part of the pipe is covered, and a means for making the pipe.

"Means for Solving the Problems" In order to achieve the above object, the internally ribbed steel pipe of the present invention is provided with protrusions that form a desired rib shape such as a spiral when rolled into a circle by means of Fuss processing. When forming a thin plate into a circular shape or forming protrusions on a thin plate, a sleeve formed into a circular shape is inserted into the tip of the steel pipe or over the entire length, and the sleeve is bonded with an adhesive or a means that can be bonded from outside the pipe, such as spot welding. It is what it is.

When the thin plate is formed into a circular shape, the protrusions formed on the thin plate mentioned above are
It is preferable to provide stress relief slits at predetermined intervals so that a predetermined protrusion shape can be maintained even when subjected to bending stress.

``Function J'' The steel pipe with internal ribs of the present invention configured as described above has the flexibility to accommodate all kinds of protrusion shapes because the protrusions are formed by press forming. Since the shape is determined by adhesion of the inner sleeve, it can be easily formed from the outside of the tube, and it can be shaped regardless of whether it is a small diameter tube, the entire length or a part of it.

"Example" Examples will be described with reference to the drawings.

- Fig. 1 is a cutaway perspective view of a steel pipe of the present invention in which only the tip portion is ribbed, Fig. 2 a - c are explanatory views of the procedure for forming protrusions on a thin plate;
FIG. 2 is an overhead view of the thin plate in a state where the protrusion press forming is completed, and a perspective view of the thin plate formed into a circular shape to form a sleeve.

In FIG. 1, reference numeral 1 denotes a ready-made steel pipe, and a sleeve 2 is integrally bonded to the inner surface of the tip end thereof.

The sleeve 2 is provided with protrusions (ribs) 2a.

Since the ready-made steel pipe 1 has a double pipe structure at a portion (the tip end) and the protrusions 2a are formed on the inner surface of the inner pipe, it becomes a steel pipe with internal ribs.

The material of the ridged sleeve 2 is a thin plate 3 made of a steel plate or a resin material, and the projections 2a are formed on the thin plate 3 by press working, as shown in FIGS. 2a and 2b.

Therefore, it is possible to form any projection, and the illustrated example (a
In Figure), the protrusions 2a on both sides of the plate 3 are continuous to form a spiral.

The protrusion 2a has stress relief slits 4 at predetermined intervals as shown in Figure b. If ... is provided, board 3
When forming the circular molded sleeve 2, ribs can be formed quickly.

Sleeving and forming the protrusions 2 may be completed in one pressing process. The sleeve 2 is bonded to the steel pipe 1 by spot welding, adhesive bonding, plug welding, single-tightening bolts, etc., which are bonding means that can be performed from the outside of the tube.

Note that the inserted sleeve 2 does not necessarily have to be seam welded in the longitudinal direction.

"Effects of the Invention" Since the present invention is configured as described above, it produces the effects described below.

i) This is a method in which ribs are added to a ready-made steel pipe in post-processing, so it is suitable because there is no need to make any troublesome changes to the existing pipe-making process.

ii) It does not matter whether the pipe is a small diameter pipe, with ribs on the entire length or part of the pipe.

iii) It is simple and economical because it is completed by gluing the insertion sleeve.

[Brief explanation of the drawing]

Fig. 1 is a cutaway perspective view of a steel pipe of the present invention in which only the tip portion is ribbed, Fig. 2 a - c are explanatory views of the procedure for forming protrusions on a thin plate;
FIG. 2 is an overhead view of the thin plate in a state where the protrusion press forming is completed, and a perspective view of the thin plate formed into a circular shape to form a sleeve. 1...Steel pipe, 2...Sleeve, 2a...Protrusion, 3...Thin plate, 4...Slit.

Claims (3)

[Claims] (1) A steel pipe with internal ribs made by adhering a press-shaped sleeve to the inside of an arbitrary rib protrusion inserted at the tip or over the entire length of a ready-made steel pipe using an adhesive or external adhesive means such as spot welding. . (2) At the tip of the steel pipe, a sleeve is formed by forming a thin plate into a circular shape with protrusions that form a desired rib shape such as a spiral when rolled into a circular shape, or by forming the thin plate into a circular shape when forming the protrusions. 2. The method for producing an internally ribbed steel pipe according to claim 1, wherein the steel pipe is inserted over a portion or the entire length thereof and is bonded with adhesive or a means capable of bonding from outside the pipe, such as spot welding. (3) The method for manufacturing a steel pipe with internal ribs according to claim 2, wherein slits for stress relief are provided at predetermined intervals in the projections when forming the thin plate sleeve.