JPH0566857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a rectangular pipe made of fiber-reinforced plastics, for example as a structural member.

Conventional technology Conventionally, a mold for a prismatic pipe was rotated around the central axis of the mold, and tension was applied to the tape-shaped long fibers impregnated with resin on the surface of the mold until a predetermined thickness was reached. After winding, it was manufactured by heating and curing without any shaping work.

Problems to be Solved by the Invention According to the above conventional method, the tape-shaped long fibers wound around the mold of the prismatic pipe do not move in the thickness direction (the sides) of the mold at the corners (corners) of the mold. However, in the flat part of the mold, the compressive force in the thickness direction is not so strong, so there is too much resin in the flat part and it swells, increasing the thickness of the product. Therefore, as the number of windings increases, the cross section of the product becomes closer to a circle, making it impossible to manufacture a predetermined square pipe.

In addition, since the resin cannot be squeezed out in the plane part where there is too much resin, the fiber content becomes small, resulting in problems such as the inability to manufacture a pipe with high strength as a product.

Means for Solving the Problems In order to solve the above problems, the present invention provides prepreg fiber-reinforced plastics (reinforcing fibers impregnated with uncured resin) to a predetermined thickness in a mold for a prismatic pipe. After wrapping a release film over it, a mold material with one side flat is applied to the entire surface of the flat part of the prism, and the prism is placed in a vacuum bag and heat-cured in a vacuum state. This removed the bulge on the flat surface that would result in too much resin.

Function According to the above method, the reinforcing fiber plastic of the prepreg, which is the flat part of the flat part of the prismatic pipe and is flat on one side, is pressurized evenly from the surrounding area by atmospheric pressure, so that the bulge due to excess resin in the flat part is prevented. As a result, the thickness of the prepreg reinforced fiber plastic wrapped around the mold becomes uniform, and the strength is also uniform.

Example As shown in the drawings, a prepreg fiber-reinforced plastic 2 is wound around a mold 1 of a prismatic pipe to a predetermined thickness to form a desired shape, and a release film 3 is applied over it. Next, the flat part 5 of the shape material 4, which is flat on one side, is pressed against the flat part 6 of the prepreg-reinforced fiber plastic 2 so as to tightly fit it with the mold 1 of the prismatic pipe, and the shape material 4 is attached to each other with tape. After being temporarily fixed, it is sealed in a vacuum bag 7 and the air inside is removed by a vacuum pump 8, and the atmosphere pressurizes the mold 4, which is flat on one side, toward the mold 1, which is a prismatic pipe. After heating in a heating furnace in such a state to harden the prepreg reinforced fiber plastics 2, the vacuum bag 7 is taken out, the vacuum is released, and the product is taken out to obtain a rectangular fiber reinforced plastics pipe.

Effects of the Invention According to the method of the present invention as described above, (a) the flat part of the shape material having one side flat is applied to the entire surface of the prismatic flat part of the prepreg fiber reinforced plastic, and the bag is sealed in a vacuum bag. To create a vacuum, the mold material is pressurized evenly in the direction of the mold.
A constant and uniform compressive force is applied to the flat part of the prepreg fiber-reinforced plastic in the thickness direction, so a highly accurate prismatic column with a constant thickness can be obtained.

(a) When wrapping prepreg fiber plastic square pipes around a mold, the process can be done on a board like making a glue roll, so the mold only needs to have low bending rigidity, and the cost of the mold can be kept low. Therefore, the manufacturing cost is also low.

(c) Since the rigidity of the mold for prismatic pipes is not required, it is possible to manufacture elongated prismatic pipes.

There are many effects such as

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention;
FIG. 2 is a perspective view of the same, and FIG. 3 is a perspective view showing the manufacturing process. DESCRIPTION OF SYMBOLS 1... Mold for prismatic pipe, 2... Prepreg fiber reinforced plastics, 3... Release film, 4... Shape material with one side flat, 5... Flat part, 6
...Plane part, 7...Vacuum bag, 8...Vacuum pump.

Claims (1)

[Claims] 1. Wrap prepreg fiber-reinforced plastic to a specified thickness around a prismatic pipe mold, then wrap a release film over it, then apply a shape material with one flat surface to the entire surface of the prismatic plane part. A method for manufacturing a fiber-reinforced plastic square pipe, which comprises placing the square column in a vacuum bag and thermally curing it under vacuum.