JPH0353851Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inner formwork for forming a hollow part of a concrete hollow member such as a hollow girder.

[Conventional technology]

Inner formwork for forming cavities in concrete hollow members such as prestressed concrete hollow girders (hereinafter simply referred to as inner formwork) has traditionally been made of wood, plywood, corrugated paper, etc., and recently, workability, low cost, etc. From the viewpoint of
173909, Jitsukai 62-173910, etc.).

Inner formwork made of corrugated paper has many advantages such as good workability, low cost, and ability to withstand shrinkage after concrete is poured. In addition, the bending strength of the joints in the longitudinal direction of the concrete hollow members is weak and requires reinforcement.

[Problem to be solved by the invention] The present invention relates to an improvement of the inner formwork made of cardboard paper among the conventional inner formworks for forming the cavity of a concrete hollow member. On the other hand, by focusing on the characteristics of the shape of the hollow part of the hollow concrete member, it is possible to reduce the number of types of members, and furthermore, to provide special reinforcement to the longitudinal joints of the hollow member. The purpose is to provide a reasonable internal formwork that does not require

[Means to solve the problem]

The present invention consists of the following technical means.

(1) A cylindrical core material formed by folding a flat sheet of corrugated paper with folds parallel to its longitudinal direction, and corrugated paper covering the outer surface of a bundle of one or more core materials. It consists of an outer covering.

(2) Each of the core materials is a cylindrical body with built-in ribs formed by cutting and raising a portion of the cardboard surface of the core material itself into the same shape as the inner surface of the core material's cross section.

[Effect]

The present invention consists of a cylindrical core material formed from a sheet of cardboard and an outer cover that covers one or more bundles of core materials.

The core material is 1 when the height of the cross section of the inner formwork is low.
If the height is high, divide it into multiple pieces in the vertical direction of the inner formwork. The inner formwork usually has the same width and various heights. Therefore, by dividing the core material in the height direction, it can be divided into standard members and height adjustment members, and the inner formwork can be formed by combining them, reducing the number of types of core materials. be able to.

In addition, each core material is formed from a single piece of cardboard paper,
Since the ribs are formed by cutting a part of the plane in the same shape as the inner surface of the cross section of the core material, the ribs can be formed without requiring a separate rib material.

By each of the above means, the inner mold of the present invention can have fewer parts than the conventional mold made of cardboard.

In addition, each core material of the present invention has ribs cut out from within the plane of a sheet of cardboard and a cylindrical body surrounding the ribs, so it is strong, easy to assemble, and highly economical. Low cost. In addition, by aligning the longitudinal direction of the corrugated reinforcement sandwiched inside the cardboard with the longitudinal direction of the core material, the strength of the cut and raised ribs in the longitudinal direction is increased, making it easier to form the core material with an accurate cross-sectional shape. In addition, the longitudinal strength of the core material is increased, and it can sufficiently withstand the load during concrete pouring, and has an appropriate strength against longitudinal shrinkage of the poured concrete.

When the core material is divided into multiple pieces, by shifting the position of the longitudinal joints of each core material, it is possible to easily improve the lack of bending strength of the longitudinal joints, which was a weak point of conventional cardboard inner forms. No countermeasures were needed.

〔Example〕

FIG. 1 shows a partially cutaway perspective view of an inner formwork 1 according to an embodiment of the present invention, and FIGS. 2 to 7 schematically show the manufacturing process thereof. The inner formwork 1 of the present invention consists of core materials 2, 3, 4 and an outer cover 5. Core material 2,
3 and 4, as shown in FIG. 2, a number of ribs 7 having a profile having the same shape as the cross-sectional inner surface of the core material are provided on a part of the inner surface of the cardboard paper of the core material, leaving the bottom side 9. Make a cut, bend the bottom part and raise it at right angles to the surface of the cardboard to form a large number of ribs 7 perpendicular to the longitudinal direction of the cardboard. The paper is folded along longitudinal folds 11 to form a cylindrical shape.

FIG. 3 shows the middle of the process of folding the corrugated paper of the core materials 2, 3, and 4 to form a cylindrical core. This shows that the situation is starting to settle in. A notch 32 is formed on the side edge of this cardboard paper at a position that matches the notch 10 provided in the rib 7.
(See Figure 2), and this notch 32
It is preferable that both sides of the rib 7 be sandwiched between the ribs 7.

FIG. 4 shows the step of stacking the cylindrical core materials 2, 3, and 4 formed as described above and covering their outer surfaces with a jacket 5.

Concrete products having a hollow part have a limited number of width dimensions and a wide variety of height dimensions of the inner formwork. As shown in Fig. 4, the inner formwork of the embodiment is a combination of core materials 2, 3, and 4 divided into three parts in the vertical direction, among which the central core material 3 can be made of multiple types that differ only in height. For example, the upper and lower core materials 2 and 4 can be made of standard products of the same shape to form a large number of inner molds. Therefore, many types of inner molds can be constructed from a small number of types of members.

Figure 5 shows the core material 2,
This figure shows how to assemble the parts 3 and 4 when the longitudinal seam positions are shifted. By shifting the seam position of the core material in this way, the present invention eliminates the need for special reinforcing of the joints, which was a disadvantage in conventional inner forms made of cardboard.

FIG. 6 shows a state in which the outer periphery of the core materials 2, 3, and 4 has been covered with the outer sheath 5, and then the end plate 6 shown in FIG.
Once installed, the fabrication of the inner formwork of the present invention is completed.

In addition, to assemble the inner formwork, apply adhesive to the surface of the cardboard, use gummed tape, etc. to temporarily fasten or adhesively connect key points, or use water-repellent paper on the surface of the inner formwork. The methods of applying water repellent treatment and water repellent treatment are the same as those of conventional techniques.

[Effect of idea]

The inner frame of the present invention is formed by covering a core material having ribs cut and raised from the core material itself with an outer cover, so that it uses a small amount of material, has high rigidity, and is easy to manufacture.

Moreover, the types of members forming the inner mold can be significantly reduced. Furthermore, reinforcing the longitudinal seams, which was a drawback of the conventional method, is no longer necessary.

Therefore, the above-mentioned excellent properties are added to the advantages of the inner formwork made of corrugated paper, such as workability, economy, and shrinkage properties, and this contributes greatly.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing the structure of an embodiment of the present invention, and FIGS. 2 to 7 are explanatory views showing the manufacturing process thereof. 1... Inner formwork, 2, 3, 4... Core material, 5... Outer cover, 6... End plate, 7... Rib.

Claims (1)

[Claims for Utility Model Registration] A cylindrical core material formed by folding corrugated paper along folds parallel to its longitudinal direction, and a corrugated paper outer cover that covers the outer surface of a bundle of one or more core materials. Each of the core materials is a cylindrical body with built-in ribs formed by cutting and raising a part of the inner surface of the cardboard paper of the core material in the same shape as the inner surface of the cross section of the core material. Inner formwork for forming hollow parts of concrete hollow members.