JPS61263735A - Molding die of fiber reinforced plastic bent pipe - Google Patents

Abstract

PURPOSE:To contrive to facilitate the load process of bending stress after the finish of filament winding and the release from a mold after heat curing by a method wherein at least two plates, the surface of each of which is made of fluoroplastic, are employed among light-gage sheets consisting of a core body and separately inserted between the remaining light-gage sheets. CONSTITUTION:Firstly, a molding die is set to a winding machine so as to wind continuous resin-impregnated fiber on the outer periphery of a core body 2 in order to form a filament layer A. Secondly, the molding tool is removed from the winding machine and jigs 3 attached to both the ends of the molding tool are replaced with tying jigs with no shaft attached. Thirdly, the core body is lent together with the filament layer A by applying bending stress in the direction of the sheet thickness of light-gage sheets. At this time, the differences among the bending radii of the light-gage sheets are absorbed by the relative slips among the sheets. The slippery property of the molding die is heightened by light-gage sheets 6 and consequently a small bending stress of the molding die is enough. Finally, the impregnated resin is cured in the state that the curvature of the molding tool is held after its bending and each light-gage sheet is drawn out successively for releasing. In this case, when the light-gage sheet 6 is drawn out fist a small force is enough in drawing-out. In addition, once the done sheet is drawn out, the drawing-out of the remaining light-gage sheets becomes easy and consequently the release from the molding mold also becomes easy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold used for manufacturing a pipe made of fiber reinforced plastics (FRP) bent at a predetermined curvature.

[Conventional technology and its problems]

When manufacturing a curved FRP pipe with a predetermined curvature by the filament winding method, in which a filament made of continuous fibers impregnated with resin is wound around a mold and then the resin is heated and hardened, the filament winding method is used. There are problems such as uneven filament, impossibility of filament wrapping due to the large curvature of the pipe, various measures required during the curing process, and increased weight due to combination with metal or other materials. , there are also technical difficulties.

For example, conventional methods include a method using a shape memory alloy as a core material (Japanese Patent Application Laid-Open No. 57-22016), and a method of forming a pipe, heating it above the heat deformation temperature, and adding an outer part to bend the pipe (Japanese Patent Application Laid-Open No. 59-1989). -21769), but the former method produces a heavy molded product because it is combined with metal, and the latter method has a limited bending range and is prone to defects such as microcracks.

If braided fibers are used as reinforcing fibers, moldability can be improved, but in this case, the fiber content inevitably decreases, and it is also difficult to manufacture large diameter pipes.

Therefore, the present inventors constructed a core body around which resin-impregnated continuous fibers were wound by stacking a plurality of thin metal plates in the same direction.
This is used as a mold, and resin-impregnated fibers are wrapped around the outer circumference of the mold.
After that, bending stress is applied in the thickness direction of the thin plate to bend the fiber layer together with the core, and after curing the resin impregnated in the fiber layer while maintaining the curvature, the thin plate is removed. Patent application for manufacturing method of bent pipes 1986-1986
It was proposed by No. 771.

This method has many features such as: 1. A product with a high fiber content can be obtained; 2. The mold can be easily bent; 2. It is easy to demold; and 2. Bent pipes with arbitrary cross-sectional shapes can be manufactured. has.

The present invention aims to further improve the above-mentioned method.
The present invention aims to provide a mold for an FRP bent pipe that further enhances the effects of (1) and (2).

[Means for solving problems]

In the mold of the present invention that achieves the above object, at least two of the thin plates constituting the core described above are plates whose surfaces are made of fluorocarbon resin, and these are inserted dispersedly between the other thin plates. It is characterized by

That is, by inserting a fluorine-based resin with good lubricity,
This makes it easier to apply bending stress after filament winding and to demold after heat curing.

〔Example〕

Embodiments of the invention are shown in the accompanying drawings.

Reference numeral 1 in FIGS. 1 and 2 is a mold consisting of a core body 2 and resultant jigs 3, 3 attached to both ends of the core body. Also, 4
shows the shaft attached to the jig 3 for mounting the mold to the winding machine.

The core body 2 is composed of a plurality of thin plates 5 made of metal or the like stacked in the same direction, and a thin plate 6 made of fluorocarbon resin inserted between them. As shown in the figure, the cross-section corresponds to the cross-sectional shape of the pipe to be formed.

The mold consisting of the above is set in a winding machine and the resin-impregnated continuous fiber is wound around the outer periphery of the core body 2. After forming the filament layer A shown by the chain line, it is removed from the winding machine and the jig 3 at both ends is attached as shown in Fig. 3. Replace the binding jig 7 with a shaft-less binding jig 7 as shown in Figure 1, apply bending stress to the thin plate in the thickness direction, and bend it together with the filament layer A as shown in the figure. This becomes much easier by inserting the . That is, the difference in bending radius of the thin plates is absorbed by relative slippage, but since the slipperiness is enhanced by the thin plates 6, the bending stress applied to the mold can be small.

After bending, the impregnated resin is cured while maintaining its curvature, and then the thin plates are pulled out one after another.
If it is pulled out, the pulling force is small and the pulling out is an intermediate wheel, and therefore, this deformation is also facilitated.

In particular, as shown in FIG. 4, if thin plates 5 made of metal or the like and fluorine resin plates 6 are arranged alternately, the sliding will be improved and it will be more effective.

Note that at least the surface of the thin plate 6 only needs to be made of fluorocarbon resin. For example, the same effect can be obtained by using a thin aluminum plate whose surface is coated with fluorocarbon resin.

In addition, the mold of the present invention can be used not only for square cross-section pipes, but also for
It can also be applied to FRP bent pipes with a round cross section. The mold 1 shown in FIG. 4, in which the cross-sectional shape of the core body 2 is circular, is used for this purpose.

L Effect] According to the present invention described above, the following effects can be obtained.

■ Thin plates made of fluorocarbon resin with a small coefficient of friction are dispersed and inserted into the multiple thin plates that make up the core, at least on the surface. Convex I gi demand + small self Seri lower mother becomes Miya easy.

■ Fluorine-based resin plates are non-adhesive, so even if excess resin flows between the laminated interfaces of the core, they will not adhere.Furthermore, fluorine-based resin plates or thin metal plates adjacent to them will have lower frictional resistance. It is easy to pull out, and therefore demolding is also easy.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the mold of the present invention, FIG. 2 is a sectional view taken along the line X-X, FIG. 3 is a perspective view of the bending process, and FIG. 4 is a perspective view of another embodiment. FIG. 3 is an example cross-sectional view. DESCRIPTION OF SYMBOLS 1... Molding mold, 2... Core body, 3, 7... Binding jig, 4... Shaft, 5... Thin plate of metal etc., 6...
・Fluorocarbon resin thin plate patent applicant: Sumitomo Electric Industries, Ltd. Agent: Kama 1) Bun 2

Claims (3)

[Claims] (1) A plurality of thin plates such as metal are stacked in the same direction to form a core around which resin-impregnated continuous fibers are wound, and after the resin-impregnated fibers are wound, bending stress is applied to the thin plates in the thickness direction. In a mold for a bent pipe made of fiber-reinforced plastics, the thin plate is removed after the fiber layer is bent together with the core and the resin impregnated in the fiber layer is cured while maintaining its curvature. A molding die characterized in that two or more of the plates are plates at least whose surfaces are made of fluorocarbon resin, and the plates are dispersedly inserted between other thin plates. (2) The mold according to claim (1), wherein the core body has a rectangular cross-sectional shape. (3) The mold according to claim (1), wherein the core body has a circular cross-sectional shape.