JPH07150686A - Shearing reinforcing bar fiber reinforced resin composite material and manufacture of the same - Google Patents

Abstract

PURPOSE:To easily form a closed configuration having a strong bent section without performing bending processing by a method wherein fibers impregnated with resin are wrapped around a square mandrel and a thermally shrikable tape is wound around the fibers, which thereafter is wrapped in a bag, and the interior of the bag is depressurized to solidify the fibers, thereby forming a molded item, and slits are formed in the molded item. CONSTITUTION:PAN-based carbon fibers impregnated with epoxy resin 2 are wound around a square mandrel 1 up to a certain thickness, following which a teflon-based thermally shrinkable tape of a predetermined width is wrapped around the fibers 2 in the same direction as the fibers, which is wrapped in a bag film and sealed. And the bag is connected to a vacuum device to place the interior of the bag under vacuum to harden the fibers, thereby forming a molded item. The molded item is then removed from the mandrel 1 and thereafter slits are formed on the item at proper intervals. As a result, a closed configuration having strong bent section can be easily manufactured in large quantities without bending it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shear-reinforced muscle fiber reinforced resin composite material embedded in a concrete formwork forming a concrete building or concrete product, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, various fiber-reinforced resin composite materials have been proposed as substitute materials for reinforcing bars. Japanese Patent Laid-Open No. 1-2060
Japanese Patent No. 22 proposes a method in which the strength of the bent portion does not decrease even when the rod-shaped fiber-reinforced resin reinforcing bar substitute is bent. Further, Japanese Patent Application Laid-Open No. 2-255323 proposes a method of winding and reinforcing the bent one with another fiber. In addition, in Japanese Patent Laid-Open No. 2-200945,
As a method that does not perform bending work, it is proposed to use a special split type mandrel and have a cross section composed of a curved line and a straight line or a curve close to a straight line.

[0003]

Of these, the first two are methods for performing bending after all, and it is impossible to completely eliminate the strain in the bent portion, and the decrease in strength of the bent portion cannot be avoided, and However, even if various reinforcement methods are adopted, the fatigue strength and impact strength will eventually decrease. Therefore, we propose a third closed shape. However, JP-A-2-200
In 945, since a special split mold is adopted, the mandrel price is high, and the workability is poor, so that it is expensive.

Therefore, it is an object of the present invention to provide a method for easily and mass-producing a closed shape having a strong bent portion without the above-described special bending work.

[0005]

In order to achieve the above object, the present invention provides a closed fiber-reinforced composite material having a square or rectangular cross-section, and winding a resin-impregnated fiber around a square mandrel. After wrapping a heat-shrinkable tape on it, it is wrapped in a bag and the inside pressure is reduced and the molded body is slit to restrict the cross-sectional shape of the closed fiber-reinforced resin composite material to a square or rectangular fiber-reinforced resin composite. The gist is the method of manufacturing the material.

Further, the present invention provides a method for improving the adhesiveness of the surface by arranging releasable fibers in a direction intersecting or orthogonal to the fiber winding direction before winding the resin impregnated fiber on the mandrel. After wrapping the resin-impregnated fiber or further winding the heat-shrinkable tape, arranging the releasable fiber on the upper surface in the same manner, and then molding, curing, de-coreing and slitting the releasable fiber on the outer and inner surfaces in the same manner as described above. A method for producing a shear-reinforced fiber-reinforced resin composite material having a groove formed therein, or forming a groove on a mandrel in a direction intersecting or orthogonal to the winding direction of the resin-impregnated fiber, and winding the fiber around the mandrel, or further a heat shrink tape After winding, press the grooved mold, then molding, curing, decoreing, slitting in the same manner as described above, a method for producing a shear-reinforced muscle fiber reinforced resin composite material having resin protrusions on the outer and inner surfaces, and this Providing the composite obtained by law.

The present invention will be described in detail below. The continuous fiber used in the present invention may be any of carbon fiber, aramid fiber, glass fiber and the like. Further, the resin may be any resin such as epoxy resin, phenol resin, and polyimide resin.

A continuous mandrel 2 impregnated with a resin is wound around a square mandrel 1 of FIG. 1 by a method such as a filament winding method, and a Teflon-based heat shrink tape is wound on the mandrel 1 to make the surface flat. Is wrapped in a bag film and sealed, and the inside of the bag is subjected to a reduced pressure of 1 to 10 torr. At this time, if the viscosity of the resin is too low, 50 to 8
Heat at 0 ° C for 8 to 16 hours to obtain a semi-cured prepreg. The reason why the degree of pressure reduction is 1 to 10 torr is that if it is less than 1 torr, it becomes an ultra-vacuum and the resin is decomposed, and if it exceeds 10 torr, sufficient degassing cannot be performed and the resin strength between fibers decreases. Because it does. Next, the bag-encapsulated product is charged into a curing furnace and cured at a temperature of about 150 ° C. to obtain a molded body, which is decoreed from the mandrel and then slit into a product with an appropriate width (FIG. 2, FIG. 2). (Figure 3). If this bug is not cured, voids will be present in the product resin and the strength will decrease, and it will not be possible to regulate the cross-sectional shape to a square or a rectangle.

Further, as a method of improving the surface adhesiveness, before winding the resin-impregnated continuous fiber, a polyethylene fiber which is releasable in a direction intersecting with the winding direction of the mandrel surface in advance, preferably in the orthogonal direction. , Teflon fibers and other fibers are arranged and fixed at appropriate intervals, and resin-impregnated continuous fibers are wound thereon, and further heat-shrink tape is wound, and then release fibers are arranged in the same direction, and then the above Similarly to the above, by performing bag molding, curing, decoreing, and slitting to remove the release fibers from the outer and inner surfaces, a grooved product as shown in FIG. 4 can be obtained. Also, after winding continuous fibers in the same manner as above on a mandrel having grooves in a direction intersecting or orthogonal to the fiber winding direction on the mandrel, a groove provided in a direction intersecting or orthogonal to the fiber winding direction After pressing the mold, similarly, bug molding, curing, decoreing,
A product having resin protrusions on the outer and inner surfaces as shown in FIG. 5 can be manufactured by slitting.

[0010]

EXAMPLE As shown in FIG. 1, a PAN-based carbon fiber 2 impregnated with epoxy resin was wound around a 196 mm × 196 mm mandrel 1 for a thickness of 5 mm, and a Teflon-based heat-shrinkable tape with a width of about 10 mm was applied on the upper surface thereof in the fiber direction. Wrapped in the same direction, wrapped all over with bag film and sealed. Connect the bug to a vacuum device and set the vacuum inside the bug to about 5 torr.
Cured at 4 ° C. for 4 hours. This molded body was decoreed from the mandrel and then slit into a width of 10 mm.

On the other hand, a 196 mm × 196 mm square product having a cross section of 78.5 mm ² using the PAN-based carbon fiber described in JP-A-2-200945 was used as a comparative example.

Products obtained by the above (Examples and comparative examples)
As shown in FIG. 6, both ends of the product (fiber reinforced composite material) 3 are embedded in concrete 4 supported through rubber 6 in a frame separated into upper and lower parts, and a tensile test of the bending portion of the shear reinforcement bar is performed. As a result, the following strengths were obtained. Example 85 kgf / mm ² Comparative example 57 kgf / mm ²

Among the comparative examples having a cross section composed of a curved line and a straight line or a curve close to a straight line, the rectangular cross section of the present invention has the same cross sectional area, stronger strength, thinner thickness direction, and more concrete fogging amount. Can be reduced.

[0014]

As described above, according to the present invention, a closed shape having a strong bent portion can be easily manufactured in a large amount without bending, and this square or rectangular cross-sectional shape is a fiber only. It is not possible to manufacture just by winding, and there is an effect that the amount of external concrete fogging is reduced as compared with those having the same sectional area curve.

In addition, the shear reinforcing fiber-reinforced resin composite material having grooves or protrusions on the outer and inner surfaces can be expected to have improved adhesion to concrete.

[Brief description of drawings]

FIG. 1 is a schematic view showing a state in which fibers are wound around a square mandrel.

FIG. 2 shows a cut cross section of a fiber-reinforced resin composite material after decoreing.

3 is a sectional view taken along the line AA ′ of FIG.

FIG. 4 shows a cross section of a grooved fiber reinforced resin composite shear reinforcement bar.

FIG. 5 shows a cross section of a fiber-reinforced resin composite shear reinforcement bar with resin protrusions.

FIG. 6 shows a state of a tensile test of a bending portion of a shear reinforcing bar embedded in concrete.

[Explanation of symbols]

 1 Square Mandrel 2 Fiber Impregnated with Resin 3 Fiber Reinforced Resin Composite Material 4 Concrete 5 Iron Plate 6 Rubber

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Ryoichi Naka 2-6-3 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation (72) Inventor Toshiaki Seki 2-8-3 Yokodai, Kimitsu, Chiba Prefecture 203

Claims (5)

[Claims] 1. A shear-reinforcing fiber-reinforced resin composite material, wherein the cross-sectional shape of a closed-shape fiber-reinforced resin composite material used as a shear reinforcing bar is restricted to a square or a rectangle. 2. The shear-reinforced muscle fiber reinforced resin composite material according to claim 1, which has grooves or protrusions on its outer and inner surfaces. 3. A rectangular mandrel is wrapped with a resin-impregnated fiber, a heat-shrinkable tape is wrapped around the wound mandrel, a bag is wrapped around a bag, and the inside is reduced in pressure to cure the molded body. A method for producing a shear-reinforced muscle fiber reinforced resin composite material, characterized in that the cross-sectional shape of the resin composite material is restricted to a square or a rectangle. 4. The method according to claim 3, wherein, before winding the fiber around the mandrel, a mold-releasing fiber is arranged in advance in a direction intersecting with the winding direction of the mandrel, and then a resin-impregnated fiber and a heat-shrinkable fiber tape are wound thereon. Place the release fiber on the upper surface,
A method for producing a shear-reinforced muscle fiber reinforced resin composite material, characterized in that after that, it has a groove formed by molding, curing, decoreing, slitting, and removing the releasing fiber on the outer and inner surfaces in the same manner as in claim 3. . 5. A groove is formed in the mandrel of claim 3 in a direction intersecting the fiber winding direction, a resin-impregnated fiber is further wound with a heat-shrinkable tape, and a grooved die is pressed, followed by molding and curing in the same manner as in claim 3. A method for producing a shear-reinforced muscle fiber reinforced resin composite material, which comprises debossing, slitting, and having a resin protrusion on the outer and inner surfaces.