JPH01160610A - Manufacture of polygonal hollow concrete member and its frame device - Google Patents

Abstract

PURPOSE:To enable the polygonal section-hollow concrete member with high quality to be produced effectively by a method in which a polygonal section inner frame is provided in a cylindrical outer frame, and the substance having similar density to concrete is packed in the space between both frames, and then uncured concrete is supplied into the inner frame and is centrifugally molded. CONSTITUTION:For instance, in the manufacture of a regular pentagonal hollow concrete member, a frame device is provided with the cylindrical outer frame 2 rotating on a pair of wheels 1, 1 and the regular pentagonal inner frame 3 arranged in contact with the inner surface of the outer frame. The space between the outer frame 2 and the inner frame 3 is filled with uncured concrete, and the solidified concrete becomes a balance weight. The outer frame 2 and the inner frame 3 are divided into two equal parts with the plane dividing their cross sections into two equal parts, and then the outer frame 2 and the inner frame 3 of these divided parts are integrally fixed. This divided parts having been integrally fixed are fastened and fixed with a bolt 6. The uncured concrete 7 is fed in the inner frame 3, and the outer frame 2 is rotated on the wheels 1, 1, whereby centrifugal molding is achieved. After its solidification, the outer frame 2 and the inner frame 3 are divided by removing the bolts 5, and a product is released from said frames.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a hollow concrete member having a polygonal cross section and a formwork apparatus therefor.

[Problem that the invention seeks to solve]

Concrete columns, piles, pipes, and other hollow bodies with circular cross-sections can be centrifugally formed using rotating cylindrical formwork, but when trying to make concrete members with polygonal cross-sections by centrifugal forming, centrifugal forming occurs depending on the direction. Due to the difference in the magnitude of the forces, the vibrations became intense and there was a risk that the device itself would be destroyed.

For this reason, conventionally, to create a hollow body with a polygonal cross section,
An inner formwork is provided within a formwork with a polygonal cross section, and fresh concrete is poured into the space between which it is compacted and formed using pie breaks. ■Methods such as attaching pieces of iron for balance weight to the outside of the polygonal formwork to adjust the centrifugal force, and rotating the formwork to perform centrifugal forming were used. However, method (2) takes more time to compact than centrifugal molding, and it is difficult to demold the inner formwork. In method (2), the size and position of the iron piece for the balance weight was determined by trial and error, which took time and effort, and it was difficult to achieve perfect balance, so smooth rotation could not be obtained.

This invention was made in view of the above-mentioned problems. The purpose is to propose a manufacturing method and a formwork apparatus that can be formed by centrifugal force, easily compacted and demolded, and capable of efficiently manufacturing high-quality hollow concrete members with a polygonal cross section.

[Means for solving the problem] The manufacturing method for this polygonal hollow concrete member involves providing an inner formwork with a polygonal cross section within a cylindrical outer frame, and centrifugally forming between the outer frame and the inner formwork. It is characterized by packing objects with a density similar to that of the concrete to give a balance weight, pouring unhardened concrete into the inner form, and centrifugally forming it into a polygonal cross-sectional shape by rotating the outer frame and the inner form. shall be.

Another formwork device according to the invention has a cylindrical outer frame having a means for rotating around its central axis, and an inner formwork with a polygonal cross-section for forming concrete attached to the outer frame. The present invention is characterized in that unhardened concrete is filled between the outer frame and the inner form and solidified to provide a balance weight.

This manufacturing method and formwork equipment is used to fill the space between the outer frame and the inner formwork with objects or concrete whose density is similar to that of the unhardened concrete that is centrifugally formed, to give a balance weight, and to fill the space between the outer frame and the inner formwork with unhardened concrete. When charging and rotomolding,
Since the centrifugal force is not unbalanced, centrifugal molding can be performed by rotating stably without vibration, and compaction and demolding can be easily performed to efficiently produce high-quality polygonal hollow concrete members.

In this invention, substances with density similar to that of uncured concrete include, for example, solidified concrete having a composition similar to that of uncured concrete, or clays whose density has been adjusted;
A sand-water slurry or the like can be used. In particular, if unhardened concrete, which has a similar composition to the unhardened concrete to be centrifugally formed, is filled between the outer frame and the inner formwork, and then solidified to give a balance weight, the weight distribution within the formwork and the outer frame will be affected. This is more preferable since it is possible to easily equalize such centrifugal force.

(Examples) The following will explain the examples shown in the drawings. Fig. 1 shows an example of manufacturing a regular pentagonal hollow concrete member. The formwork device used for this manufacturing rotates on a pair of wheels 1.1. It has a cylindrical outer frame 2 and a regular pentagonal inner frame 3 arranged in contact with the inner surface of the outer frame 2, and unhardened concrete is filled between the outer frame 2 and the inner frame 3 and is hardened. The balance weight is given by the object.

The outer frame 2 and the inner frame 3 are divided into two by a common plane that bisects the cross section, and the outer frame 2 and the inner frame 3 of the two divided parts are outward from the divided end face of the inner frame 3. The two flanges 5.5 protruding from the outer frame 2 are fixed to each other via two flanges 5.5, and the integrated two-part part is fixed by fastening the flanges 5.5 with bolts 6 on the outside of the outer frame 2 to form a formwork device. There is.

In order to manufacture a regular pentagonal hollow concrete member using this formwork device, unhardened concrete 7 is put into the inner formwork 3, the outer frame 2 is rotated on wheels 1.1, and centrifugally formed. The concrete 7 inside the inner formwork 3 can maintain stable rotation in balance with the concrete 4 outside the inner formwork, and the compaction of concrete by centrifugal force can be actively promoted. Furthermore, after solidification, the outer frame 2 and the inner frame 3 can be easily demolded by removing the bolts 5 and dividing them into two parts.

The embodiment shown in FIG. 2 is an embodiment of manufacturing a square hollow concrete member. The formwork device used for this production has a cylindrical outer frame 2 that rotates on wheels 1.1 and an inner formwork 3 with a square cross section that is attached to the inner surface of the outer frame 2. A balance weight is given by an object made by filling uncured concrete between the two and solidifying it. Also, 2
As in the embodiment shown in FIG. .5
are fastened and fixed with port 6 to form a formwork device.

In this embodiment, the inner formwork 3 of the formwork apparatus configured in this way is
Inside, a perforated plate 8 with a square cross section is arranged with a small gap maintained between it and the surface of the inner formwork 3, and this perforated plate 8 has a large number of permeable holes 9. A water-permeable filter material 10 made of synthetic fiber fabric is lined on the inner surface of the filter.

In order to manufacture a square hollow concrete member using this formwork device, uncured concrete 7 is poured into a perforated plate 8 with filter material 10 on the inside, and the outer frame 2 is placed on the wheels 1.1. Rotate and centrifugally mold. At this time, the concrete 7 maintains stable rotation in balance with the concrete solidified material 4, and compaction of the concrete 7 is promoted.

At the same time, free water in the concrete 7 is pushed outward from the concrete 7 by centrifugal force, passes through the filter material 10 and the water permeable holes 9, collects on the inner surface of the inner form 3, and is forcibly discharged. Although not shown, a small drainage hole communicating with the outside of the outer frame 2 is provided at the corner of the inner frame 3.

When a concrete member is made using the method shown in Fig. 2,
Since the concrete is well compacted and free water is actively discharged from the outer surface, a dense structure with a low water-to-cement ratio can be created. In addition, in conventional centrifugal molding, slime is discharged from the inner hollow part, which requires considerable processing effort, but with this method, free water is filtered through a filter material and does not contain slime, reducing the burden of wastewater processing. . The filter material may be a synthetic fiber fabric, a nonwoven fabric, a porous film, or the like, as long as it is permeable to water and substantially not permeable to particles such as cement or fine aggregate.

〔Effect of the invention〕

The present invention is as described above, and according to this manufacturing method and formwork apparatus, a polygonal hollow concrete member can be formed by centrifugal molding, and a compacted member can be manufactured efficiently.

Additionally, if a perforated plate laminated with filter material is placed inside the inner form and free water is actively discharged, the concrete structure can be made even denser.

[Brief explanation of the drawing]

The drawings show examples, and Fig. 1 is a longitudinal sectional view of the formwork device in the manufacturing state of a regular pentagonal hollow concrete member, and Fig. 2 (al and (b)) is a longitudinal sectional view of the formwork device in the manufacturing state of a regular rectangular hollow concrete member. They are a vertical sectional view and a side view partially shown in cross section of the formwork device. 1... Wheels, 2... Outer frame, 3... Inner formwork, 4...
- Solidified concrete, 5... Flange, 6... Bolt, 7... Uncured concrete, 8... Perforated plate, 9... Water permeable hole, 10... Filter material.

Claims (2)

[Claims] (1) An inner formwork with a polygonal cross section is provided within a cylindrical outer frame, and an object with a density similar to that of the concrete to be centrifugally formed is packed between the outer frame and the inner form to provide a balance weight. . A method for manufacturing a polygonal hollow concrete member, characterized in that concrete that has not hardened yet is placed in the inner form, and centrifugally formed into a polygonal cross-sectional shape by rotating the outer frame and the inner form. (2) An outer frame having a cylindrical shape and having a means for rotating around its central axis, and an inner formwork with a polygonal cross section for concrete molding attached to the outer frame, and the outer frame and the inner form A formwork device for a polygonal hollow concrete member, characterized in that unhardened concrete is filled between the frame and the frame, and the unhardened concrete is solidified to give a balance weight.