JPH028582A - Steel pipe with projection and manufacture thereof - Google Patents

Abstract

PURPOSE:To strengthen a steel pipe by forming a network projection on at least one of the inner and outer surfaces of the steel pipe. CONSTITUTION:A network projection 111 is formed on at least one of the inner and outer surfaces of a steel pipe 1. According to this construction, the projection 111 comes to strengthen the steel pipe 1 and it becomes possible to increase the strength of the pipe 1 even when the weight thereof is equivalent to the weight of a conventional steel pipe. Furthermore, the aforesaid network projection 111 can also work for substantially improving adhesion with concrete.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a steel pipe provided with reticular protrusions on the inner or outer surface or both the inner and outer surfaces, and a method for manufacturing the same.

(b) Prior art In recent years, steel pipes have been used in a wide range of applications such as fluid transport pipes, structural supports and beams, foundation piles, and concrete composite steel pipes.

Some conventional concrete composite steel pipes have protrusions on the inner or outer surface or both the inner and outer surfaces of the steel pipe in order to strengthen the adhesion of concrete, but these protrusions do not improve the strength of the steel pipe itself. Moreover, none of the protrusions were continuous in a net-like manner. Further, in conventional structural supports, beams, foundation piles, etc., there are no protrusions provided on the inner or outer surface or both the inner and outer surfaces of the steel pipe with the intention of improving the strength of the steel pipe.

As mentioned above, conventional steel pipes provided with various protrusions to increase the adhesion between concrete loaded inside the pipe and the inner surface of the steel pipe, and methods for manufacturing the same, can be broadly classified as follows.

(2) Continuous protrusions in one direction are arranged parallel to the inner peripheral surface of a steel pipe (for example, Japanese Patent Publication No. 59-49118).

■ Discontinuous protrusions are arranged on the inner peripheral surface of the steel pipe using a rolled steel plate with discontinuous protrusions (for example,
8-106439, Japanese Patent Publication No. 5922115).

■ Steel pipes with gold g
Utility Model Application Publication No. 50-52705).

However, all of the above-mentioned conventional techniques have the following problems.

■ Adding protrusions will significantly increase processing costs or make steel pipe manufacturing more complicated.

■ The protrusions are not arranged effectively to increase the load-bearing capacity of the steel pipe itself. Although the spiral protrusions have the effect of increasing adhesion depending on the direction, the protrusions hardly contribute to reinforcing the steel pipe itself. . Furthermore, even when the height of the protrusions is increased in order to increase the adhesion force, the reinforcing effect of the protrusions on the steel pipe itself is extremely partial, and the protrusions are not fully utilized. It is not effective in increasing the load-bearing capacity of the steel pipe itself.

(c) Problems to be Solved by the Invention The problems to be solved by the present invention are to improve the strength of steel pipes, to also strengthen their adhesion to concrete, and to develop a simple manufacturing method for such steel pipes. There are seven things you can get.

(d) Means for Solving the Problems The steel pipe with projections of the present invention solves the above problems by forming linear projections on at least one of the inner and outer surfaces of the steel pipe.

Here, the term "striated protrusion" refers to a protrusion that is raised from at least one of the inner and outer surfaces of a steel pipe to a certain height or more and extends continuously in a straight or curved manner on that surface. A protrusion in which the strips intersect with each other to define a mesh-like surface area of a subdivision.

The method for producing a steel pipe with protrusions of the present invention includes forming reticular protrusions on at least one of the front and back surfaces of a steel plate by rolling, and forming the steel plate into a steel pipe by spiral splicing or longitudinal splicing. The above issues have been resolved.

(E) Function In the steel pipe with projections of the present invention, the projections forming the projections are continuous, and the projections have at least two or more directions at the intersection of the projections, so that the reticulated projections contributes to reinforcing the steel pipe against external forces acting on the steel pipe (for example, external bending force on the steel pipe, external force at the drilling point, external force in the tube axis direction, external impact force, etc.).

Furthermore, the reticulated projections can also serve to further improve the adhesion to concrete, and the steel pipe of the present invention functions as a steel pipe for concrete composite steel pipes.

(e) Examples Embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1 and FIG. 2, in the steel pipe 1 with projections of the present invention, a mesh-like projection 11 is formed on at least one of the inner and outer surfaces of the steel pipe 1.

Here, the term "reticular protrusion" refers to a protrusion 111 that is raised from at least one of the inner and outer surfaces of the steel pipe 1 at a certain height or more and extends continuously in a linear or curved manner on that surface; It refers to a protrusion 11 in which protrusions 111 intersect with each other to define a surface portion 112 of a small section in a mesh shape.

An example of the protrusion 11 is shown in FIG. 3. FIG. 3 is an enlarged development view of a part (circle surrounded by a two-dot chain line) of the outer surface of the steel pipe 1 shown in FIG. FIGS. 3(A) to 3(E) show a protrusion 11 consisting of a protrusion 111 extending linearly. Figure 3 (A), (
B) shows a protrusion 11 consisting of a protrusion 111 extending in two directions, FIGS. 3(C) and (D) in three directions, and FIG. 3(E) in four directions.

In addition to the above-mentioned protrusion 11, FIGS.
) may be a protrusion 11 consisting of a protrusion 111 extending in a curved shape.

Furthermore, the cross-sectional shape of the protrusion is shown in FIGS.
) may be of various shapes. The projections 11 shown in FIGS. 3 and 4 may be provided on the inner surface or both the inner and outer surfaces of the steel pipe 1.

From the viewpoint of the strength of the steel pipe 1, it is preferable to provide a ridge having a large height and a narrow width (for example, as shown in FIGS. 5(^) and 5(B)). This is because a steel pipe with greater cross-sectional performance can be obtained with the same weight of material.

On the other hand, the steel pipe 1 of the present invention fully functions as a concrete composite steel pipe. That is, if concrete is loaded onto the surface of the steel pipe 1 provided with the protrusions 11, sufficient adhesion performance can be obtained.
As shown in B), since the protrusions 111 are provided so as to intersect with each other, even if cracks occur in the concrete at a part of the contact surface between the protrusions 111 and the concrete, the protrusions continue in a spiral pattern. Some of the steel pipes of the present invention do not have the disadvantage that the cracks propagate in the direction of the ridges and grow, causing the synthetic steel pipes to lose their strength, unlike conventional synthetic steel pipes with The cracks that occur remain localized. Therefore, the strength of the synthetic steel pipe is greater than that of conventional ones.Also, when concrete is poured on site, the height of the protrusions 111 should be taken into account, considering dirt from mud, oil, etc. on the protrusion surface of the steel pipe, and shrinkage of the concrete. From a practical point of view, it is desirable that the number h (FIG. 6) be 21 or more.

Also, if we focus on the protrusions extending within 45 degrees from the pipe circumferential direction Y (Fig. 1), the method for setting these protrusions is as follows:
As shown in FIG. 6, the pinch (P
) is the ratio (P/h) of pitch CP) and protrusion height (h)
If at least one protrusion is set on the side of the steel pipe where concrete is loaded so that the rising angle (θ) of the protrusion with respect to the steel pipe surface is 60 degrees or more so that the The steel pipe of the present invention is also provided with protrusions that intersect with the protrusions related to adhesion performance, so cracks in the concrete may occur at some locations on the protrusions related to adhesion performance. Even though
The intersecting protrusions stop crack growth and improve adhesion performance compared to conventional synthetic steel pipes.

When using the steel pipe of the present invention as a member of a structure,
The height of the protrusions constituting the net-like protrusion and the arrangement density of the protrusions can be set according to the strength required of the member.In other words, in order to increase the strength of the steel pipe, the protrusions should be continuous, All you need to do is make the protrusions higher and increase their arrangement density.
In addition, in order to effectively provide protrusions of the same weight from the viewpoint of strength, it is better to equalize the arrangement density of the protrusions on the inner or outer circumferential surface of the steel pipe. It is better to make it as large as possible. That is, the third
In the protrusion pattern shown in Figure (B), if the spacing (pitch) between the protrusions set in one direction is approximately equal to the pitch between the protrusions set in the other direction, and the height of the protrusions is also increased, the protrusions This method is effective as a reinforcement method for steel pipes.

A method of manufacturing such a steel pipe with projections will be described below.

First, as shown in FIGS. 8 to 10, continuous mesh projections 21 are formed on at least one of the front and back surfaces of the steel plate 2 by rolling.

For example, a roll having grooves corresponding to the reticular protrusions 21 carved along the roll circumferential direction at a predetermined axial position on the body of at least one of a pair of rolls is installed in the final rolling stand. When the steel plate is rolled, a part of the steel plate enters the grooves cut into the rolling rolls during rolling, and the steel plate 2 with projections of the present invention can be easily manufactured.

Similar to the aforementioned protrusions 11, the reticular protrusions 21 are protrusions 211 raised from the surface of the steel plate 2 at a certain height or more and continuously extending in a linear or curved manner on the surface.
intersect with each other to define the surface portion 212 of the small section in a mesh pattern.

After the steel plate 2 is manufactured into the steel pipe 1 by the pipe manufacturing method described later, the protrusion 21 becomes the protrusion 11, the protrusion 211 becomes the protrusion 111, and the mesh surface portion 212 becomes the surface portion 112.

Next, a steel pipe 1 with protrusions is manufactured by using the steel plate 2 as shown in FIG. 11 by a spiral joint pipe manufacturing method or by a dip joint pipe manufacturing method as shown in FIG. 12.

As best shown in FIGS. 7 and 8, the steel plate 2 with protrusions is available in two types: a type (B) in which connecting portions 22 are provided on both sides of the steel plate 2 in the longitudinal direction, and a type (A) in which the connecting portions 22 are not provided.

When spirally splicing or longitudinally splicing the steel plates 2 with protrusions, it is preferable to provide the connecting portion 22 in order to improve the efficiency of pipe manufacturing. Furthermore, the thickness of the connecting portion 22 is set to be appropriately larger than the plate thickness of the surface portion 212 of the steel plate with projections 2 from the viewpoint of reinforcing the connecting portion when forming into a steel pipe and forming the steel plate with projections by rolling. It is desirable to leave it there.

When the protrusions 21 are provided on both sides of the steel plate 2, the protrusions 21 on each side of the steel plate 2 may be provided offset from each other as shown in FIGS. 9 and 10. The method for setting the protrusions 21 is as follows: This is preferable from the point of view of making the strength of the steel pipe 1 uniform (Fig. 2 (C)
)reference).

As shown in FIG. 12, when pipe-making the steel plate 2 by longitudinal splicing, the horizontal axis X' and the vertical axis Y' of the steel plate 2 are the same as the pipe axis direction (Fig. 1), respectively.

However, as shown in FIG. 11, when the steel plate 2 is made into a pipe by spiral wrapping, the two do not match, and the direction of the protrusion 111 of the produced steel pipe 1 is the same as the spiral wrapping angle (β). Involved. This angle (β) is determined by the steel plate width (-), the pipe diameter (D),
There is the following relationship with pi (π).

Therefore, for example, if the protrusion 211 of the steel plate 2 is set in a direction forming a spiral winding angle (β) determined from the above equation with respect to the horizontal axis X' of the steel plate 2, the protrusion 211 of the steel pipe l Similarly, the protrusion 211 corresponds to the circumferential direction Y of the pipe (FIG. 11(A)), and similarly the protrusion 211 has a spiral winding angle (β) -45 degrees with respect to the horizontal axis X' of the steel plate 2. (β)+4
If the protrusion 211 is set in a direction that makes an angle of 5 degrees), the protrusion 211 is provided in a direction that makes an angle of 45 degrees or less with respect to the circumferential direction Y of the steel pipe 1.

When the steel pipe 1 with protrusions of the present invention is used as a concrete composite steel pipe, if concrete is loaded onto the surface of the steel pipe provided with the mesh-like projections, the adhesion between the concrete and the steel pipe surface is high, so that a synthetic steel pipe with high strength can be obtained. I can do it. An example of use as a concrete composite steel pipe is shown in Fig. 13.

Figure 13 (A) shows a synthetic steel pipe filled with unreinforced concrete on the inner side of the steel pipe 1, (B) shows a synthetic steel pipe filled with fiber reinforced concrete on the inner side of the steel pipe 1, and (C) shows a synthetic steel pipe filled with unreinforced concrete on the inner side of the steel pipe 1. A synthetic steel pipe filled with a hollow part on the inner surface of the steel pipe 1, (D) is a synthetic steel pipe filled with reinforced concrete in the same manner as in the example in (C), and (E) is a synthetic steel pipe filled with unreinforced concrete on the outer surface of the steel pipe 1. (F) shows a synthetic steel pipe loaded with unreinforced concrete on both the inner and outer surfaces of the steel pipe 1.

In the ready-made steel-concrete composite steel pipe as shown in Figure 13(C), a flat steel pipe without protrusions 11 is used as the steel pipe, and an expanding agent is mixed into the concrete to ensure the required adhesion force. At present, if the steel pipe 1 with projections of the present invention having projections 11 provided on the inner surface is used, the required adhesion force can be ensured, so that the use of an additional expansion agent can be omitted.

(f) Effects According to the present invention, since the protrusions provided on the steel pipe reinforce the steel pipe, it is possible to provide a steel pipe with higher strength even if the weight is the same as a conventional steel pipe, and furthermore, it can be used as a concrete composite steel pipe. The adhesion performance with concrete is further improved.

Further, in manufacturing the steel pipe of the present invention, conventional rolling methods and pipe manufacturing methods can be effectively utilized without major changes.

The steel pipe with protrusions of the present invention can be used for foundation piles of structures such as bridges and buildings, steel pipe sheet piles for bank protection and earth retaining walls, pillars of buildings, bridge piers, members of power transmission towers, steel pipe jacket structures, and river erosion control structures. The present invention can be used in a wide range of applications, such as members of steel pipe truss structures, and the synthetic steel pipe obtained by filling the protruded steel pipe with concrete according to the present invention can also be used in a wide range of applications similar to those described above.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a steel pipe with projections of the present invention. Figure 2 is the first
A cross-sectional view taken from the line ■-■ in the figure. FIG. 3 is an enlarged view of a portion cut out from the area enclosed by the line ``■'' in FIG. 1, showing various protrusion patterns. FIG. 4 is a drawing similar to FIG. 3, showing other various protrusion patterns. Figure 5 is a cross-sectional view of various protrusions. FIG. 6 is an explanatory diagram showing an example of the dimensional relationship of the protrusions. Fig. 7 is a plan view of a steel plate with protrusions used for manufacturing the steel pipe with protrusions of the present invention, and Fig. 8 is the line ■A-■A and ■B of Fig. 7.
-■ Cross-sectional view seen from line B. Figure 9 is a plan view of another steel plate, Figure 10 is a cross-sectional view taken along the line X-X in Figure 9, and
1 and 12 are explanatory diagrams of the method for manufacturing a steel pipe with projections of the present invention. FIG. 13 is a cross-sectional view of various steel pipes when the protruded steel pipe of the present invention is used as a concrete composite steel pipe. : Steel pipe with protrusions: Steel plate with protrusions 11.21 : Protrusions 111.211 : Projections 22 : Connection bars 112.212 : Surface portion

Claims (1)

[Scope of Claims] 1. A steel pipe with protrusions, characterized in that a reticular protrusion is formed on at least one of the inner and outer surfaces of the steel pipe. 2. A method for manufacturing a steel pipe with protrusions, which comprises forming reticular protrusions on at least one of the front and back surfaces of a steel plate by rolling, and forming the steel plate into a steel pipe by spiral splicing or longitudinal splicing.