JPH0239772Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a formwork for forming a concave part for fixing the end of a prestressing prestressing steel material into a concrete product by post-tensioning.

In terms of rust prevention for fixed ends and tension ends of PC steel materials,
Furthermore, in order to prevent the ends of these PC steel materials from protruding from the concrete product and resulting in poor appearance, recesses are formed in the concrete product.
After the end of the prestressing steel material is tensioned and fixed in the recess, the recess is filled with concrete or the like.

Conventionally, when forming such a recessed part in a concrete product, as shown in FIGS. 1 and 2, a truncated quadrangular pyramid-shaped formwork body 4' is used as a formwork 3' for forming the recessed part. The insertion hole 7' of the prestressing steel material insertion hole forming member 6' is formed in the axial direction of this, and the formwork main body 4' is fixed to the inner surface of the formwork 8' for making concrete products. As well as wearing
The hole forming member 6' is inserted into the hole 7' of the formwork body 4', and concrete is poured between the formworks 8', 15', and after a predetermined curing period, the formworks 8', 15',
By removing 3' and hole forming member 6', a recessed part 2' and a PC steel insertion hole are created in concrete product A'.
It is designed to form c′.

Then, in the recessed part 2', the PC steel material 1'
After fixing the tensioned end, the recessed portion 2' is filled with mortar or concrete 19'.

According to the above structure, although the form body 4' is formed into a truncated square pyramid shape to facilitate demolding of the form body 4', the form body 4' is It is quite difficult to pull out the
In addition, at this time, the corners of the recessed part 2' tend to collapse, and as shown in FIG. 3, the concrete 19' filled in the recessed part 2' and the concrete product
The boundary line d' with A' was distorted at the corner of the recessed part 2', resulting in poor appearance.

Furthermore, when a plurality of recesses 2' are provided in the concrete product A', or when one recess 2' is provided,
When arranging individual concrete products A' of the same shape vertically or horizontally, when fixing the formwork body 4' to the formwork 3' for making concrete products, the formwork body 4' If the fixed position of ' is shifted around the axis of the formwork body 4',
The mutual postures of the rectangular recesses are disturbed, and as a result, as shown in FIG. 3, the shape of the boundary line d' becomes disordered in the mutual posture.
In this respect as well, it looked bad.

This kind of inconvenience, for example,
Publication No. 13370, Publication No. 57-40174, Publication No. 1987-40174, Publication No. 13370
As seen in Japanese Patent No. 40176, etc., this problem can be solved by making the mold body 4' into a truncated cone shape.

However, even if the form body 4' is shaped like a truncated cone, the following disadvantages cannot be avoided.

That is, the recessed part 2' of the concrete product A' formed by removing the formwork body 4' from the concrete product A' has a truncated conical shape with a smooth inner peripheral surface and an outward expansion. After fixing the end of the prestressing steel material inside 2' and introducing prestress into the concrete product A', when the recessed part 2' is filled with mortar or concrete 19', the mortar and concrete 19' There is a possibility that it may fall out of the recessed portion 2', and this disadvantage becomes more pronounced as the draft angle of the form body 4' becomes steeper.

Furthermore, even if the mortar or concrete 19' filled in the recessed part 2' is firmly attached to the concrete product A', the concrete product A' that has been concreted and cured in advance and the concrete product A' Post-filling (filling) in the recessed part 2'
Since the color is markedly different from the mortar and concrete 19', the mortar and concrete 19' attract attention and spoil the aesthetic appearance.

The object of the present invention is to provide a mold for forming a concave portion for fixing a PC steel material, which can eliminate these disadvantages.

Therefore, the technical means taken by the present invention to achieve the above object are as follows. That is, the formwork for forming the recessed part for fixing the PC steel material according to the present invention is as follows:
PC for introducing prestress using post tension
A formwork for forming a concave part for fixing the end of a steel material into a concrete product, which is removable from the formwork for forming a concrete product, and is capable of inserting a member for forming a PC steel material insertion hole along the axial direction. A male screw is provided on the circumferential surface of the truncated cone-shaped formwork body in which a hole is formed, and a set part of a rotation operating tool for screwing the formwork body out of the concrete product is provided on the large diameter side surface. It is characterized by

According to the above configuration, after the concrete hardens,
By rotating the formwork body around the axis of the formwork body relative to the concrete product using a rotating operation tool, the formwork body comes out of the concrete product by screw action, and the concrete product has no internal parts. A recessed portion with a female thread is formed on the circumferential surface.

Hereinafter, embodiments of the present invention will be explained based on the drawings from Fig. 4. Fig. 4 shows a partial cross section of an elevated road.
Girders A... are lined up in the width direction and erected on pillars not shown, and the PC steel materials 1, 1 for introducing prestress by post-tensioning are inserted, and the PC steel materials 1, 1 are buried and spaced. This shows the state in which concrete B has been placed, prestress has been introduced, and pavement C has been applied to the upper surface.

The legs of both sides of the PC girder A...
As shown in FIG. 5, a recessed portion 2 is provided for fixing the tensioned end of the prestressed steel material 1.

The specific structure of the formwork 3 for producing the recessed portion 2 is shown in FIG. As is clear from the figure, this formwork 3 is provided with a male screw 5 on the circumferential surface of a truncated conical formwork main body 4, in which both the peaks a and troughs b are curved, and is made of PC steel. The insertion hole 7 of the insertion hole forming member 6 is aligned with the form body 4 in its axial direction (the form body axis P and the hole axis _P1 are aligned, but both axes P, There is no problem even if P ₁ is slightly shifted. Fastening parts 10, 10 consisting of screw holes for fastening the frame body 4 with bolts 9, 9, and a square hole-shaped set of rotary operating tools (for example, square wrench) for rotating the form body 4. A hole 11 is provided.

Furthermore, an annular recess 12 is formed around the insertion hole 7 in the small-diameter side surface _S1 of the form body 4, and a magnet 14 for magnetically attracting the bearing plate 13 for tensioning the prestressed steel material is provided. It is buried in the recess 12.

Although the set portion 11 is formed concentrically with the insertion hole 7, it may be provided at a different location, or may also serve as the fastening portions 10, 10.

Further, a stud bolt may be provided on the large-diameter side portion S, and this may be used as the fastening portion 10.

The hole forming member 6 is a metal pipe, and a sheath tube 16 made of a bellows-shaped thin iron plate that abuts the opposing surfaces of the bearing pressure plate 13 and the mold frame 15 is fitted onto the outside.

Now, in the set state of the formwork 3 shown in FIG. 6, concrete is poured on-site between the formworks 8 and 15 for producing concrete products, and after a prescribed curing period, the formworks 8 and 15 are removed, and the formwork 3 from the concrete product A and pulling out the hole forming member 6 with the sheath pipe 16 left in place, the recessed part 2 for fixing the tensioned end of the prestressing steel material can be formed as shown in FIG. As shown in FIG. 8, the PC steel material 2 is inserted into the hole c formed by the sheath pipe 16, and the PC
Fit the sleeve 17 and wedge 18 onto the steel material 2,
Moreover, by applying post tension to the PC steel material 2, fixing of the tensioned end of the PC steel material 2 is completed.

Then, as shown in FIG. 9, the recessed portion 2 is filled with mortar or concrete 19.

At this time, as shown in FIG. 10, the deep part of the recessed part 2 is filled with concrete 19, etc., with the tensile end of the prestressed steel material 1 buried, and the opening part is filled with a cover body 20 made of concrete made in advance. It may be screwed on, and in such a case, as shown in the virtual diagram, the lid body 20
If a design pattern 20a such as a floral pattern is applied to the surface, it looks good and is suitable for buildings.

Incidentally, the male thread 5 of the form body 4 is hardened by high frequency or the like.

FIG. 11 shows another embodiment, in which the form body 3 is hollow, and the bearing plate 13 is attached to the end face 3a with bolts 2.
The feature is that it is temporarily fixed in step 1. still,
In this embodiment, the demolding is done at the fastening part 1 consisting of a screw hole.
0 and 10 are also used as the above-mentioned setting part 11, that is, by inserting an appropriate rotary operating tool into both the fastening parts 10 and 10.

Since the present invention has the above-described configuration, it can achieve the following effects.

That is, a male threaded portion is formed on the circumferential surface of the form body, a set portion for a rotation operating tool is formed on the large diameter side surface, and the form body is rotated by the rotation operation tool.
Since the formwork body is removed from the concrete product by screw action, the formwork body can be easily removed, and at the same time, there is no internal thread on the inner circumferential surface of the recessed part to be formed into the concrete product. Therefore, when the recess is filled with mortar or concrete, the concrete, etc. enters the valley of the female thread, which functions as an anchor, and it is possible to reliably prevent the filled concrete, etc. from falling out.

In addition, it is possible to screw the lid onto the open end of the recess by using the internal thread formed on the inner circumferential surface of the recess, and the lid can be used to fill concrete, etc. It is possible to improve the appearance of concrete products by hiding them.

In addition, as the external thread shape of the outer peripheral surface of the formwork body, both the peaks and valleys are curved.
Care has been taken to prevent the female threads of the concrete product from collapsing as much as possible during demolding of the formwork body, but the male threads are not shaped like trapezoidal threads, square threads, etc.
Alternatively, it may be made into an angle-shaped screw shape.

[Brief explanation of the drawing]

Figures 1 to 3 show conventional examples; Figure 1 is a cross-sectional view of the formwork for forming the recessed part, Figure 2 is a cross-sectional view of the state in which concrete is filled into the recessed part, and Figure 3 is the front view of the concrete product. It is a diagram. Figure 4 and subsequent figures relate to the embodiment of the present invention. Figure 4 is a partial sectional view of an elevated road, Figure 5 is a partially cutaway end view of a concrete product, and Figure 6 is a recessed part for fixing prestressing steel. Fig. 7 is a partial sectional view of the concrete product showing the forming condition of the recessed part, Fig. 8 is a sectional view showing the tensioned end of the prestressing steel material, and Fig. 9 is a sectional view showing the setting state of the forming formwork. FIG. 10 is a sectional view of a state in which concrete is filled into the recessed portion, and is a sectional view of another embodiment corresponding to FIG. 9. FIG. 11 is a sectional view showing another embodiment. DESCRIPTION OF SYMBOLS 1... PC steel material, 2... Recessed part, 4... truncated conical form body, 5... Male thread, 6... PC steel insertion hole forming member, 7... Insertion hole, 8... Concrete product Formwork for production, 10... Attaching part, 11...
...Set part, A...Concrete product, S...Large diameter side part.

Claims (1)

[Scope of utility model registration request] For introducing prestress by post tension
A formwork for forming a concave part for fixing the end of a prestressed steel material into a concrete product, which is removable from the formwork for forming a concrete product, and a member for forming a prestressed steel material insertion hole along the axial direction. A male thread is provided on the circumferential surface of the truncated cone-shaped formwork body in which an insertion hole is formed, and a set part of a rotation operating tool for screwing the formwork body out of the concrete product is provided on the large diameter side surface. A formwork for forming a recessed part for fixing a PC steel material.