JPS6334127A - Manufacture of fiber reinforced plastic cylinder - Google Patents

Abstract

PURPOSE:To simultaneously form a plurality of cylinders, each of which has a corrugated part at the midway in longer direction of fiber reinforced plastic (FRP) by a method wherein, after a continuous resin-impregnated fiber is wound round an inner mold, the fiber is peripherally cut off between a plurality of uncured cylinders in continuously connected state and further flexible structure parts are provided at both ends of a forming section per one viscoelastic body of the cylinder. CONSTITUTION:A fiber-wound layer 6 is formed onto an inner mold 1, and, after that, the fiber is peripherally cut off at a point indicated with the arrow between uncured cylinders in continuously connected state. Flexible structure parts 11b and 11c, the wall thickness of which is thinner than that of a main body part, are respectively formed at the middle and both ends in the axial direction of a cylindrical mold 11. The inner mold 1, onto which the fiber-wound layer 6 is formed, is inserted in an outer mold 10 by enlarging the inner diameter of a mold 11 through the evacuation of the air space part 13 of the outer mold 10. After that, the air space part 13 is pressurized through a hole 15 so as to apply molding pressure through the cylindrical mold 11 to the fiber-wound layer 6 in order to cure the layer 6 by heating. Two FRP cylinders A are simultaneously obtained by removing the inner mold from the cured layer 6.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to a method for manufacturing a cylinder made of fiber reinforced plastics (hereinafter referred to as FRP), and more specifically, a method for manufacturing a cylinder body made of fiber reinforced plastics (hereinafter referred to as FRP). The present invention relates to a method for simultaneously molding a plurality of cylindrical bodies having irregularities.

[Conventional technology]

An FRP cylindrical body with unevenness in the longitudinal direction is made by winding continuous fibers impregnated with resin by the filament winding method (hereinafter referred to as FW method) on a split mold that can be disassembled in the circumferential direction. For fiber wrapping, a method is employed in which an outer mold is placed over the layer, and the impregnated resin is cured under a state in which the layer is pressurized using this outer mold.

When mass-producing FRP cylindrical bodies obtained by such a method, there are two methods: increasing the number of molds, and making multiple molds with one mold and forming many with one winding. Although it is conceivable, the former method cannot be expected to be very effective in mass production, and therefore the latter method should be used for mass production, but the following problem arises when the conventional technology is extended.

[Problem that the invention seeks to solve]

That is, if we consider that the target FRP cylindrical body is a cylindrical body A with a bellows in which a bellows part exists in the middle of the cylindrical part a, as shown in FIG. Even if resin-impregnated continuous fibers are wound on top using the FW method, the fibers do not necessarily follow the surface of the inner mold, especially in the bellows molded part.

Therefore, in many cases, the desired shape is obtained by covering the resin with an outer mold based on a rubber-like viscoelastic material and curing the resin under pressure from the outer mold. When multiple-piece molding is applied to overlaying, the fibers in each bellows part are simultaneously tensioned by the pressure applied by the outer mold.
When wrapped between the bellows parts, the fibers stretch and separate from the cylindrical molding surface of the inner mold between the bellows parts, making it difficult to align the raised portions with the molding surface even if external pressure is applied.

In addition, if the viscoelastic body is provided with unevenness corresponding to the bellows, as in the case of one piece, the molded part per cylindrical body is considered to be one unit due to the change in the shape of the viscoelastic body over time. Sometimes, the position and shape of the uneven molding surface for each unit are not constant, which causes the problem that the uneven shape of the product becomes unstable, making it impossible to obtain a highly reliable FRP product.

The purpose of the present invention is to solve the above-mentioned two problems and to make it possible to mass-produce (mold) an FRP cylindrical body with high shape and dimensional accuracy.

[Means for solving problems]

The method of the present invention that achieves the above object solves the problem of fiber lifting between uneven parts due to tension of the fibers due to pressurization in the outer mold, and after wrapping the resin-impregnated continuous fibers around the inner mold, The problem was solved by adding a process of cutting the fibers in the circumferential direction between multiple uncured cylinders in a continuous state, and also to prevent the deterioration of the shape accuracy of the uneven part due to the deformation of the rubber-like viscoelastic body of the outer mold over time. The problem is solved by providing flexible structural parts at both ends of the molded part of each viscoelastic cylindrical body.

(Function) The tension of the fibers when pressurized by the outer mold is due to the fact that the fibers are continuous. Therefore, as mentioned above, the fibers are cut around the entire circumference between a plurality of uncured cylindrical bodies. Once this is done, the behavior of the fibers under pressure will be independent for each uncured cylinder.
The result is no different from single-cavity molding, and the fibers follow the inner mold surface well when wrapped.

Further, when a flexible structure is provided in the rubber-like viscoelastic body of the outer mold, deformation of the viscoelastic body is concentrated in this flexible structure because deformation of the flexible structure is easier than elsewhere. Therefore, unnecessary deformation of the concavo-convex molding surface is alleviated, and the molding surface fits onto the fibers in a normal position and in a normal shape.

〔Example〕

Hereinafter, the present invention will be described in detail by taking as an example the case where two FRP cylindrical bodies A shown in FIG. 4 are manufactured at the same time. In the case of FIG. 1, the inner mold 1 used has a structure in which two ring-shaped cylindrical molding molds 2.2 and an uneven molding mold 3 are arranged on a core bar 4. The concavo-convex molding die 3 is divided into a plurality of parts in the circumferential direction, and each divided body has a shoulder part 5 provided at each end.
is pressed by the cylindrical mold 2 and placed on the core metal 4. In addition, the illustrated concavo-convex molding die 3 has bellows molding parts 3a, 3a.
Although the cylindrical molded part 3b is included therebetween, the two bellows molded parts 3a, 3a may be made independent from the cylindrical molded part 3b. In this case, the cylindrical molded portion 3b can have a cylindrical shape.

In addition, the inner mold 1 is demolded after molding by pulling out the core bar 4, then pulling out each segment of the mold 3 radially inward and removing the cylindrical mold 2 axially. , an inner mold may be used in which each divided body of the mold 3 is connected to a drive mechanism and moved forward and backward in the radial direction.

In this invention, resin-impregnated continuous fibers are wrapped around the inner mold configured as described above using the FW method, but before that, a thin film made of synthetic resin is covered on the inner mold (and an uncured The resin is prevented from flowing into the space between the split surfaces of the inner mold, making subsequent work easier.Also, it is possible to obtain a cylindrical body with good leak resistance by integrating the thin film with the FRP layer.

After the fiber wrapping layer 6 is formed on the inner mold 1 in this manner, the fiber is cut in the circumferential direction between the continuous uncured cylinders (points indicated by arrows in FIG. 2). After this, the outer mold 10 shown in FIG. 3 is attached onto the inner mold 1 on which the fiber wrapping layer 6 has been formed.

The outer mold 10 has as basic elements a cylindrical mold 11 made of a rubber-like viscoelastic material whose molding surface 11a has a shape that matches the outer peripheral surface shape of the molded product, and an outer mold 12 that holds the cylindrical mold 11 from the outside. The 0 cylindrical mold 11, which has a cavity 13 between them, has both ends sandwiched between an annular lip 12a provided on the inner surface of both ends of the outer mold and a retaining ring 14, and the clamping portion is It also serves as an airtight seal at both ends of the cavity 130 whose radial space dimension is determined by the height dimension of the lip 12a. 15 is a hole for pressurizing or depressurizing the cavity 13.

Further, flexible structure parts 11b and 11C, which have a thinner wall thickness than the main body part, are formed at the axial center and both ends of the cylindrical mold 11, respectively.

In the outer mold 10 constructed as described above, when the pressure inside the cavity 13 is reduced through the hole 15, the cylindrical mold 11 is sucked radially outward, and the inner diameter of the mold 11 is expanded. Therefore, in this expanded state, the inner mold 1 with the layer 6 formed thereon is inserted into the outer mold 10, and after this, the inside of the cavity 13 is returned to normal pressure, and the fiber wrapping is performed with the layer 6 formed.
A cylindrical mold 11 is brought into contact with the top. Furthermore, after this, the inside of the cavity 13 is pressurized through the hole 15, and forming pressure is applied to the fiber wrapping N6 via the cylindrical mold 11. Then, under this pressurized state, the uncured resin impregnated into the fibers is heated or otherwise cured.

After that, if you mold the inner mold by reversing the procedure above, the fourth mold will be formed.
Two FRP cylindrical bodies A shown in the figure are obtained at the same time.

Note that the flexible structure parts 11c at both ends of the cylindrical mold 11 have been conventionally provided for the purpose of facilitating insertion of the inner mold, but in the case of a multi-cavity cylindrical mold, this alone does not suppress deformation of the molding surface 11a. In particular, when pressurizing, 11C alone cannot absorb the tensile force acting on the cylindrical shape, and as a result, it stretches over the main body, deforming the molding surface. However, the outer cylindrical mold 11 used in this invention has 11C in addition to 11C.
(b) has a flexible structure, and the tensile force acting on the main body is absorbed by the elongation of these two flexible structures, so deformation of the molding surface is effectively prevented.

It should be noted that, in addition to the example of thinning the flexible structure, it is also possible to have pleats with good elasticity, but considering the ease of manufacturing the cylindrical mold 11, the flexible structure in the form shown is advantageous. .

〔effect〕

As explained above, according to the present invention, the uneven F
The problem of fiber tension during pressure molding in multiple RP cylinders was solved later by cutting the fibers between continuous uncured cylinders, and rubber-like The problem of deformation of the cylindrical molding surface made of an elastic body was solved by providing a flexible structure at both ends of the molding part of each cylindrical body, so the unevenness with good dimensional and shape accuracy was achieved. The effect is that it becomes possible to mold the attached FRP cylindrical body with good mass productivity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of an inner mold used in the present invention;
Fig. 2 is a cross-sectional view of the inner mold in which the resin-impregnated fibers are wound and inserted, Fig. 3 is a cross-sectional view showing an example of the outer mold used in the present invention, and Fig. 4 is a cross-sectional view showing an example of the outer mold used in the present invention. It is a side view showing an example of the FRP cylindrical body obtained by the method. 1... Inner mold, 2.2... Cylindrical part mold, 3... Concave and convex part mold, 4... Core bar,
6...Fiber wrapping is a layer, 10...Outer mold,
11... Cylindrical type, lla... Molding surface,
11b, 11C...Flexible structure part, 12...
・Outer mold, 13...Gap, 15...
Hole, A...FRP cylindrical body. Patent applicant Sumitomo Electric Industries, Ltd. Agent Kama 1) Text 2 Figure 1 Figure 3 Figure 2 Figure 4

Claims (2)

[Claims] (1) A method for simultaneously molding a plurality of fiber-reinforced plastic cylindrical bodies having unevenness along the longitudinal direction,
A concavo-convex mold that is independent of at least the cylindrical molds at both ends is divided in the circumferential direction, and each of the divided bodies is supported so as to be movable or removable in the radial direction. Wrap the fibers directly or after placing a synthetic resin thin film layer, then cut the fibers in the circumferential direction between a plurality of continuous uncured cylinders, and then wrap the cylinders on the fiber wrapping layer. Each molded part has a cylindrical shape made of a viscoelastic body with a flexible structure at both ends, and an outer cylinder that surrounds and holds this from the outside, and there is a gap between the cylindrical shape and the outer cylinder. Cover the prepared outer mold with the cavity under reduced pressure, and then
A method for producing a cylindrical body made of fiber-reinforced plastics, which comprises releasing the vacuum in the void, bringing the cylindrical mold into close contact with the fiber-wrapped layer, and hardening and molding the fiber-wrapped layer. (2) The method for manufacturing a cylindrical body made of fiber-reinforced plastics according to claim 1, wherein the flexible structure is created by partially thinning a cylindrical main body.