JP2001173140A - Cap for pipe made of thin steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cap having an excellent strength which can be adhered easily to a pipe made of thin steel plates to be used for the constitution of a hollow portion of a concrete structure. SOLUTION: A gutter with a groove-shaped cross section with the end edge portion of the pipe fitted to the outer peripheral portion of a back plate covering the opening end portion made of the thin steel plate pipe is formed around the whole periphery. The end portion of the pipe is fitted to this gutter and fixed with screws from the outer periphery portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cap for covering the open end of a thin steel pipe used as a hollow member of a concrete structure.

[0002]

2. Description of the Related Art Hollow structures are often used in concrete structures such as viaducts and buildings in order to reduce the weight and improve rigidity, and a cylindrical mold is used as a hollow member for molding the hollow structures. Frames are used. This cylindrical form (hollow member) is called a cylindrical form for viaducts, and a hollow slab pipe for building slabs. The hollow member is formed into a pipe by spirally winding a strip-shaped thin steel plate. FIG. 2 shows an example of this. The rigidity of the pipe 10 is improved by spirally forming a crimped portion (goby) 11 and a corrugated rib 12 in a spiral shape. According to this method, pipes of various diameters can be manufactured using the same strip-shaped thin steel plate.

When a hollow slab or a floor slab is formed by using this kind of pipe 10, the openings 10a at both ends of the pipe are covered with caps so that cast concrete does not enter the pipe. If the fixing strength to the pipe is low, the cap is broken or detached due to buoyancy acting when casting concrete.

Therefore, conventionally, as shown in FIG. 5, a cap C is covered so as to cover the outer surface of the pipe 10, and the outer peripheral portion is screwed or gas welded at an appropriate interval. In some cases, screwing and gas welding may be used together. As shown in FIG. 6, there is also a method in which a cap C ′ is fitted into the inner peripheral portion of the pipe 10 and the contact portion B between the outer edge of the cap and the pipe is gas-welded over the entire circumference.

[0005]

In the conventional method shown in FIG. 5, a cap is put on the pipe so as to cover the pipe and the outer peripheral portion is screwed or gas welding is performed at an appropriate position. When gas welding is adopted as the fixing method, there is a problem in that it requires man-hours and time for gas welding, and since it is a thin steel plate, skill is required for welding. Further, in the case where screws are fixed as a fixing method, since the resistance to an external pressure load mainly acts on the screws, there is a problem that the screws are cut or the pipe and the cap are separated due to slippage of the screw portion.

Further, in the method shown in FIG. 6, the cap is fitted into the inner peripheral portion of the pipe, and the outer peripheral portion of the cap and the pipe are gas-welded all around, so that the man-hour and time required for gas welding are further increased as compared with the above-mentioned method. However, there is a problem that skill is required. In this method, since the compressive force acts on the back plate via the flange, there is an advantage that there is little possibility of cracking or breakage of the welded portion. The present invention
It is an object of the present invention to solve the problems of the conventional cap and to provide a cap which can be fixed to a pipe by a simple method and has excellent strength.

[0007]

In order to solve the above problems, the present invention employs the following configuration. That is, the cap for a thin steel pipe according to the present invention is a cap for covering an open end of a thin steel pipe as a hollow member of a concrete structure, and a back plate for covering the end of the pipe. A groove having a gutter-shaped cross section in which an end portion of the pipe fits is formed around the entire periphery of the pipe.

[0008] This cap is formed by fitting an end portion of a pipe into an annular groove provided in an outer peripheral portion and fixing an appropriate position on the outer periphery with a screw, so that the cap is not used without welding. Can be firmly fixed to the pipe.
Since the external pressure at the time of placing concrete acts on the back plate, no shearing force acts on the screws.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically based on embodiments of the present invention shown in the drawings.
FIG. 1 shows an example of a thin steel pipe cap (hereinafter abbreviated as “cap”) of the present invention. The cap 1 has a groove 3 having a U-shaped cross section formed on an outer peripheral portion of a flat back plate 2. Are formed. The groove 3 is formed integrally by curving the peripheral edge of the back plate 2, and the groove bottom 3 a protrudes outside the outer surface of the back plate 2. Further, the side plate portion 3 b forming the outer wall of the groove 3 protrudes inward from the inner surface of the back plate 2. This cap 1 can be applied to a pipe having a large diameter (400 Φ or more). Pipes for hollow slabs and cylindrical molds with a diameter of 400 Φ or more are products of various kinds and small quantities, so if they are molded by a sheet metal press, dies and the like become expensive and are not economical. In this regard, since the cap 1 in the illustrated example can be manufactured by turning a flat plate into a circular plate with a cutting machine and then pressing it with a turning machine, it is easy to manufacture and suitable for high-mix low-volume production.

FIG. 3 and FIG.
The cap 1 is attached so that the thick portion 10 b at the open end of the pipe 10 fits into the groove 3. Since the groove bottom 3a of the cap 1 projects outside the outer surface of the back plate 2, in this mounted state, the back plate 2 of the cap slightly (t) fits inside the opening of the pipe 10. Become. The cap is fixed to the pipe by screws (bolts) 5 in this mounted state. In FIG. 3, for example, the dimensions of each part are, for example, D
Is about 35 mm, t is about 15 mm, and h is about 7 to 8 mm. In some cases, instead of fixing with these screws, the screws may be fixed by welding, or welding and screw fixing may be used together.

The cap 1 has a U-shaped groove 3 formed in an annular shape around a back plate 2 for covering the opening of the pipe 10. The end of the pipe 10 is inserted into the U-shaped groove and fixed. The side plate 3b of the cap is in a state of covering the outer peripheral portion of the end of the pipe. For this reason, the screws 5, which penetrate the side plate 3b of the cap and the pipe 10, can be screwed in from an appropriate position on the outer peripheral portion where the caps are in contact with each other to fix them.
Therefore, there is no need to perform welding requiring skill.
Further, the external pressure load P such as the buoyancy at the time of placing concrete and the load resulting from the combination of the gravitational force and the weight of concrete after the completion of placing is given.
However, since this load mainly acts on the back plate 2 and no shearing force acts on the screws 5, no damage is caused on the screws.

Further, when the cap 1 is mounted on the pipe 10, the back plate 2 of the cap fits inside the end of the pipe 10 as described above, so that the finger fits into the groove wall portion 3c of the fitted cap. Can be multiplied. For this reason, handling such as transportation is easy. The shape of the groove 3 may be a U-shaped square groove at the bottom of the groove, but a U-shaped groove having a rounded outer surface as shown in the example shown in FIG. It is also excellent in strength.

Next, FIG. 7 shows an example in which a hollow concrete slab is formed by using the pipe 10 with the cap 1 as a hollow member, and the pipes 10 with the cap 1 covered at appropriate intervals. The concrete 30 is cast on a formwork with a reinforcing member interposed between the hollow members adjacent to each other. By this casting, for example, as shown in FIG.
A concrete structure containing 5,... Is obtained.

[0014]

As is apparent from the above description, the cap according to the present invention covers the open end of the thin steel pipe so that the thick part of the pipe fits into the groove, and screws from the outer periphery. Therefore, it can be efficiently and easily fixed to the pipe using an electric wrench or the like.
In addition, since welding that requires skill is not required, anyone can easily mount it. Furthermore, even if an external pressure load due to the casting of concrete acts on the cap, almost no shearing force acts on the screw for fixing the cap, so there is no risk of the screw being damaged or coming off as in the prior art. In this type of concrete structure, the larger the diameter of the pipe, the greater the external pressure load is applied at the time of concrete casting. Therefore, durability is required by that much, but if the cap of the present invention is used, the durability is as described above. This is particularly effective for large diameter pipes.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (a) and a front view (b) of a cap illustrating an embodiment of the present invention.

FIG. 2 is an external view of a pipe.

FIG. 3 is a sectional view of a main part in which a cap is fixed to a pipe.

FIG. 4 is a side sectional view showing a state of attachment to a pipe.

FIG. 5 is a side sectional view showing a state in which a conventional cap is mounted.

FIG. 6 is a side sectional view showing a conventional example different from the above.

FIG. 7 is an explanatory view of a hollow slab molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cap 2 Back plate 3 Groove 5 Screw 10 Pipe

Claims (3)

[Claims] 1. A cap for covering an open end of a thin steel pipe as a hollow member of a concrete structure, wherein the pipe has an edge on an outer peripheral portion of a back plate that covers the end of the pipe. A cap for a thin steel pipe, wherein a groove having a trough-shaped cross-section to which is fitted is formed over the entire circumference. 2. The cap for a thin steel pipe according to claim 1, wherein the groove is formed in a U-shaped cross section, and the bottom of the groove projects outside the surface of the back plate. 3. The thin steel pipe cap according to claim 1, wherein the end of the pipe and the cap are fixed with a plurality of screws.