JPH01314111A - Manufacture of pipe made of carbon-fiber-reinforced concrete - Google Patents

Abstract

PURPOSE:To shorten possessory hours of a mandrel by making removal of a core of the mandrel easy, by a method wherein after initial stage curing of a carbon fiber impregnated with cement water paste by winding the carbon fiber round a hollow mandrel whose diameter is enlarged by interposing an insertion material into a slit part, the insertion material is removed. CONSTITUTION:After interposition of an insertion material 2 into a hollow mandrel 1, a carbon fiber 3 impregnated with cement water paste is laminated to the mandrel 1, which is coated with a coating film 4. After progress of an initial stage curing up to a state where a main laminate can be demolded, the insertion material 2 is removed, the diameter of the hollow mandrel 1 is contracted and a core of the laminate with a progress in cure is removed. With this construction, removal of the core of the mandrel can be performed easily without having fear of damaging a pipe at a stage where the initial curing is completed. Since repeating use of the mandrel is possible, the title method is economical. A hard polyvinyl chloride pipe, polypropylene pip, fiber- reinforced synthetic resin pipe are suitable especially as the hollow mandrel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a high-strength carbon fiber-reinforced cement pipe using continuous carbon fiber as a reinforcing material and a cement composition as a matrix.

(Prior Art and Problems) In recent years, carbon acei has attracted attention as a reinforcing material for cement compositions because it has high specific strength and specific modulus, and is excellent in chemical resistance, corrosion resistance, etc.

However, in the past, when reinforcing cement compositions with carbon fibers, the fibers were often shortened and mixed with other materials. When using Short III, compared to using Soorizo,
The effect of its strength and elastic modulus is small, and due to kneading problems, the volume content of carbon fiber is at most 5%'f
! Up to once.

There is also a method of reinforcing cement compositions using long fibers of carbon fibers and aramid l1I11.These long fibers are used as reinforcing materials to create rod-shaped resin compositions with organic synthetic resins such as epoxy resins and vinyl ester resins as a matrix. Alternatively, molded products such as rope-shaped products are made, and these products are being used in place of reinforcing bars.

However, in this case, since the matrix is an organic substance, it has poor fire resistance and heat resistance, and since the shape of the molded product is rod-shaped or rope-shaped, there is a problem that the molded product inevitably becomes thick when embedded in a cement composition. There is.

A composite material with carbon fiber as a reinforcement and a cement composition as a matrix can solve this problem of fire resistance and heat resistance, and because extremely thin carbon fiber filaments are uniformly present in the cement composition, It is possible to make the molded product thinner.

Conventionally, as a method of manufacturing pipes using continuous carbon 1111 as a reinforcement and a cement composition as a matrix, continuous carbon fibers impregnated with cement water paste are wound around a mandrel and stacked, the cement is initially cured, and then cored from the mandrel. A method is being considered.

However, when the initial curing time is short, the strength of the cement pipe is very weak and it will be destroyed by a small load.

Furthermore, if the secondary curing is performed while the molding material is wound around the mandrel until the cement has sufficiently hardened, it will take a long time and the mandrel will be occupied for a long time, which is not economical.

Furthermore, there is a method in which paper tubes are used as mandrels and stacked, and after initial shelling and hardening, the paper tubes are immersed in water to swell and peeled off, but this method is not economical because the paper tube mandrels are disposable.

[Purpose of the invention]

The present invention solves the above-mentioned problems, and provides an efficient method for manufacturing a carbon fiber-reinforced cement pipe that facilitates mandrel decore and shortens the mandrel occupation time.

(Structure and operation of the invention) The present invention is as follows.

(1) An insertion material is inserted into the slit part of a hollow mandrel having continuous slits in the axial direction to increase the outer diameter of the hollow mandrel, and in this state, carbon fiber impregnated with cement water paste can be wrapped around it and removed from the mold. Carbon 1 characterized in that after initial curing to a state of
A method for manufacturing a vibrator made of ntIIr1 reinforced cement.

<2> The method for manufacturing a carbon fiber-reinforced cement pipe according to claim (1), wherein the hollow mandrel is a hard polyvinyl chloride pipe, a polypropylene pipe, or a fiber-reinforced synthetic resin pipe.

(3) The method for manufacturing a carbon fiber-reinforced cement pipe according to claim (1), further comprising performing a second curing after the core is removed.

In the present invention, the hollow mandrel needs to be made of a material that can push and expand the slit of the hollow mandrel when setting the insertion material in the slit. Particularly suitable as such a hollow mandrel are hard polyvinyl chloride pipes, polypropylene pipes, and fiber-reinforced synthetic resin pipes.

Commercially available plastics, rubber,
It may be made of metal or the like.

The width of the insert material is 0.1 to 100 mm around the outer circumference of the mandrel.
A range of 1.0 is desirable. If the width is more than 1, the distortion of the mandrel is large (and the shape of the molded product is also distorted).If the width is less than 0.1, the reduction in the outer diameter is small and decentering is not performed effectively.

In the present invention, initial curing refers to curing that starts immediately after molding and hardens to the point where it can be removed from the mold and transported.
Next curing means curing to further increase the strength after the initial curing.

Simply curing means curing from initial curing to secondary curing.

The present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view of a mandrel used in the method of the invention. FIG. 2 is a perspective view showing a state in which a molding material is wound around the mandrel shown in FIG. 1.

As shown in FIG. 2, after inserting an insert 2 into a hollow mandrel 1, a molding material 3 (carbon fiber impregnated with cement water paste) is laminated and covered with a covering film 4.

A hollow mandrel in the state shown in Figure 1 was prepared using carbon millimeters impregnated with cement water paste using a sheet winding method.
Wind it circumferentially to the required thickness.

Next, the charcoal XalJi impregnated with this cement water paste was
Hollow mandrel laminated with H, polyester tape,
Covering with polypropylene tape, polyvinyl chloride tape, etc. prevents moisture from evaporating and at the same time prevents the laminated shape from deforming. After curing in air for 24 hours at 20°C, the initial curing is progressed to a state where the laminate can be demolded, and then the insert material is removed, the diameter of the hollow mandrel is reduced, and the hardened laminate is released. Core.

Further, if necessary, secondary curing such as hot water curing or autoclave curing can be performed.

The continuous carbon fiber impregnated with cement water paste that is wound around the mandrel may be in the form of a strand or a sheet.

A so-called filament winding method can be applied to wind and number the carbon fibers in the form of a strand, whereby the orientation of the carbon fibers can be arbitrarily adjusted.

Moreover, when winding in a sheet form, the following sheet-like molded intermediates are suitably used.

A patent application has already been filed for this intermediate, and is this a fine cement water paste? ! Therefore, it is a continuous carbon fiber bundle that is opened and impregnated, and is a sheet in which carbon fibers are aligned in one direction.

In the present invention, this sheet-like molded intermediate is cut into predetermined dimensions, and the carbon fibers are laminated and wound while changing the direction of orientation of the carbon fibers depending on the purpose. The carbon fiber used here is not particularly limited as long as it is a continuous fiber, and may be any one of PAN type, pitch type, cellulose type, etc.

(Effects of the Invention) According to the method of manufacturing a pipe made of carbon-Illlled Cemeton of the present invention, the mandrel can be easily decoreted without fear of damaging the pipe after initial curing.

Further, the present invention is economical because the mandrel can be used repeatedly, and according to the present invention, a carbon fiber reinforced cement pipe with good quality can be provided at a low cost.

[Examples and comparative examples]

Example 1 Outer diameter 267 mm 1 Wall thickness 7.8 InI1 1 Length 200
A slit was provided in the axial direction of a 0 mm hard polyvinyl chloride tube, and an insertion material made of silicone resin with a width of 5 mm and a thickness of 5 cm was inserted into the slit to form a scissor mandrel.

Carbon fiber bundles impregnated with cement water paste are placed on the hollow mandrel with this insertion material interposed at a thickness of ±45''.
The product was laid up in a 3-layer structure, the outer periphery of the product was covered with polyvinyl chloride tape, and the product was left standing at 20° C. for 24 hours.

The inner diameter of the formed pipe is 268mm and the length is 1800m.
m.

The wall thickness was 13 mm.

Next, the insertion material of the mandrel was removed inside, the outer diameter of the mandrel was reduced, and the core was removed. De-coring was easy without the use of a machine, and there was no damage to the molded product. Then,
It was left standing in warm water at 50°C for 48 hours.

The obtained carbon fiber reinforced cement pipe had a roughly circular shape.

Comparative Example 1 For comparison, a hard polyvinyl chloride pipe without slits was laid up in the same manner as in Example 1, and after being allowed to stand at 20° C. for 24 hours, an attempt was made to decore it, but the molded product was damaged.

In addition, after laying up the pipe, it was left to stand at 20°C for 24 hours, and then left to stand still in warm water at 50°C for 48 hours to de-core, but the pulling force for de-coring was 2.9 tons when handling the pipe from the mandrel.
On was necessary.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a mandrel used in the method of the invention. FIG. 2 is a perspective view showing a state in which a molding material is wound around the mandrel shown in FIG. 1. Explanation of symbols in the figures 1: Hollow mandrel, 2: Insert material, 3: Molding material, 4:
Covering film patent applicant ll! Marushi Yong Shoroku Company Representative Patent Attorney Doi 3 Department Figure 1 Figure 2

Claims (3)

[Claims] (1) An insertion material is inserted into the slit part of a hollow mandrel having continuous slits in the axial direction to increase the outer diameter of the hollow mandrel, and in this state, carbon fiber impregnated with cement water paste can be wrapped around it and removed from the mold. A method for producing a carbon fiber-reinforced cement pipe, characterized in that after initial curing to a state in which the inserted material is removed, the outer diameter of the hollow mandrel is reduced and cored. (2) The method for manufacturing a carbon fiber-reinforced cement pipe according to claim (1), wherein the hollow mandrel is a hard polyvinyl chloride pipe, a polypropylene pipe, or a fiber-reinforced synthetic resin pipe. (3) The method for manufacturing a carbon fiber-reinforced cement pipe according to claim (1), further comprising performing a second curing after the core is removed.