JPH0447927A - Hollow frame and production thereof - Google Patents

Abstract

PURPOSE:To mold a hollow frame enhanced in reliability and bonding efficiency and having an external shape almost same to an unbonded part by bonding and reinforcing hollow split bodies from the inside and outside thereof by forming overhang parts wherein the end parts of the hollow split bodies overhang the center direction of the hollow frame and providing a striplike notched part to the hollow frame along the outer surface thereof. CONSTITUTION:A drop mold is bonded to a split mold 5 at a part to be overlaid using a tape 6 and the tape 6 is used as a part of a mold. The single surface of the tape 6 to be used is subjected to release treatment. After lamination, overhang parts 2 becoming bonding parts are provided. In the molding of the overhang parts 2, protruding materials are laminated to the inside of the mold using protruding plates 7 made of FRP. When strength is required, lightweight resin concrete 4 is embedded in the overhang parts 2. The overhang parts 2 are coated with an adhesive to match and bond a two-piece mold. The recessed part formed by peeling off the tape 6 is filled with a matrix of a reinforcing fiber such as a carbon fiber and a thermosetting resin to mold and finish an overlay part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an FRP hollow frame formed by overlapping two hollow divided bodies and a method for manufacturing the same.

As a specific example of a hollow frame, for example.

Examples include bicycle monocoque frames, surfboards, buoys, and display products.

[Conventional technology]

There are four conventional hollow frames and methods for molding them:

■Method of butting the ends of two hollow divided bodies and laminating and bonding their upper surfaces with reinforcing fibers and matrix resin (the lamination method is overlay) (see Figure 4) ■A flange is provided around the area forming the hollow divided body.

Method of joining by gluing and/or bolts etc. at this flange part (see Figure 5) ■ Processing the joint wall to enlarge the joint area of the wall of the hollow divided body and then bonding,
Next, there is a method of overlaying the joined part with reinforcing fibers from the outside of the closed space (see Figure 6). ■ A method of increasing the bonding area and joining by increasing the thickness of the abutting part of the hollow segment from the inside (see Figure 6). (See Figure 7) [Problems to be Solved by the Present Invention] Among the conventional techniques, the method (2) increases the reliability of the bonding surface, but since the bonding is performed by laminating only from the outside, bonding efficiency cannot be expected. This means that the external force acting on a hollow closed space is
This is because a bending load normally acts on the joint surface, and as a result, a tensile load is generated inside the joint surface, and the strength of the joint at that portion becomes insufficient. Therefore, it cannot be applied to items that require strength, such as bicycle frames.

In addition, because the overlay is performed directly from the outside, protrusions appear on the outside.

Method (2) has the best reliability and strength of the bonded surface, but because it creates large protrusions on the outside, the product becomes larger than originally planned, and is not suitable for products that require a smooth appearance. Not applicable, and this method may result in increased weight.

Method (2) improves method (2) by increasing the area of the joint surface and reducing the rigidity of the joint surface at the tip of the joint.
Although it has the property of delaying the occurrence of peeling, post-processing of the bonded surface is extremely difficult, and for example, it is impossible to process objects with three-dimensional bonded surfaces.

In method (2), precision of the joint surface is required, and depending on the molding method, it is very difficult to form the joint surface, and reliability tends to be poor. Also, because the joints are thicker, deformation is more likely to occur.

The weight also increases. Furthermore, since the rigidity of the bonded portion increases, peeling is likely to occur, and the bonding efficiency is not as high as expected.

The present invention overcomes the drawbacks of conventional hollow frames, and provides a hollow frame with high reliability and high bonding efficiency,
Furthermore, the present invention provides a hollow frame whose external shape is almost the same as that of the non-jointed portion, and a method for molding the hollow frame.

[Means to solve the problem]

The present invention provides an FRP hollow frame formed by overlapping two hollow divided bodies, in which the ends of the hollow divided bodies have (i) an overhanging portion extending toward the center of the hollow frame;
) The hollow frame has a band-shaped notch along the outer surface, and when the two hollow divided bodies are joined, the hollow frame completely fills the recess formed by the notched part of the two hollow divided bodies. The present invention relates to a hollow frame characterized in that an overlay portion is provided to prevent unevenness on the frame.

Another aspect of the present invention is that when molding the FRPli hollow divided body, a tape-like material is attached to a portion corresponding to the notch of the mold for molding the hollow divided body. The hollow frame is formed by molding, and then the hollow divided bodies are overlapped before or after peeling off the tape-like material, and the overlay portion is embedded in the recessed portion where the tape-like material was present to integrate the hollow frame. Regarding the molding method.

That is, the hollow frame of the present invention is characterized in that an overhang for joining is provided in the inner direction of the closed space to widen the joint area and improve strength, and the product surface is free from unevenness. . It is preferable that this overhanging portion is made of the same FRP as the main body, and for those requiring zero strength, it may be a hollow frame in which the overhanging portion is filled with lightweight resin concrete.

Further, the hollow frame of the present invention is characterized in that since the overlay portion on the outer periphery of the main body is provided as a recess, there is no unevenness on the surface of the product after overlaying with a material of an appropriate size.

The method for manufacturing the hollow frame of the present invention will be explained below using molding by hand layup method as an example.

The mold is a split mold (see Figure 2).

A drop mold is attached to the split mold 5 to prevent unevenness on the surface of the product when overlaid. Use tape 6 for the drop mold and attach it to the part to be overlayed. Here, the tape 6 is used as part of the mold. Note that the tape 6 used has one side subjected to mold release treatment.

Lamination is performed using the resin-impregnated glass mat in the mold, and after lamination, an overhang 2 that becomes a joint is attached (see FIG. 3). The overhanging portion 2 is formed by laminating the overhang inside the mold using FRP overhanging plates 7. For those requiring zero strength, the overhanging portion is filled with lightweight resin concrete 4.

Adhesive is applied to the overhanging portion 2 created in the above step, and the two parts of the mold are aligned and bonded. At this time, the two-part mold is firmly fixed using a fixing jig.

After that, the product is released from the mold. After releasing the mold, tape 6
The overlay part 3 is finished by molding reinforcing fibers such as carbon fibers or glass fibers and a matrix of thermosetting resin in the recessed part created by peeling off the tape 6.

The hollow frame of the present invention is given as a specific example.

It can be applied to bicycle monochork frames, surfboards, buoys, display products, etc.

〔Example〕

Next, the present invention will be explained with reference to examples.

As shown in FIG. 2, a tape 6, one side of which had been subjected to release treatment, was attached to the mold 5. Here, we used double-sided tape made of butyl rubber. The location where the tape is applied is the area where the overlay will be applied. In this case, the dimensions of the tape are not particularly limited, but as an example, the product was laminated onto a zero order mold with a thickness of 0.5 mm and a diameter of 10 mI. For lamination, carbon cloth was used as the reinforcing fiber and vinyl ester resin was used as the matrix resin. After lamination, an overhang 2 is attached to the inner side,
The diagram is shown in Figure 3. As shown in FIG. 3, the overhanging portion 2 was laminated and molded on the inside of the mold using the overhanging plate 7. The same material as the laminated material of the product was used for the overhang, and lightweight resin concrete 4 was filled in the overhang. The lightweight resin concrete used was a mixture of epoxy resin (603 manufactured by Nippon Devcon) and glass micro balloons (manufactured by 3M). The overhanging plate 7 is made of FR made by laminating a glass mat with a matrix (vinyl ester H-6700 made by Mitsui Toatsu).
It was made of plastic using the mating surfaces of a mold, and was divided into pieces of a certain size for use. After molding.

The overhang plate 7 was removed from the molded product, leaving the overhang portion 2 intact. This process was similarly performed on the other mold that was divided into two parts.

FIG. 1 shows a joined hollow frame according to the present invention. Adhesive was applied to the overhanging portion 2 formed in the above step, and the two molds were bonded together, and then the tape was removed from the mold, the tape 6 was peeled off, and the overlay portion 3 was filled. The adhesive used here was concrete bond (manufactured by Konishi E-250). In this case, the width of the overlay part is 20
It was recessed with dimensions of 0.5 m and depth of 0.5 cm, and this position was overlaid with resin-impregnated reinforcing fibers of this size to finish.

The three-point bending strength of the structure of the present invention manufactured in this manner is shown in comparison with that of an integral structure without bonding and a structure formed by a conventional method (① external overlay method).

From the above, the effects of the present invention are clear. In particular, by applying this invention, it is expected that the degree of freedom in the shape of FRP products will be expanded.

〔Effect of the invention〕

The hollow frame of the present invention can be joined from the inside and outside of the hollow divided body,
Because it is reinforced, the joint strength is improved compared to conventional products that could only be reinforced from one side. Furthermore, the hollow frame of the present invention has no protrusions on the outside, can be molded without changing its original external shape, and has an improved appearance compared to conventional products.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the hollow frame of the present invention, Figs. 2 and 3 are diagrams showing the method of forming the structure of the present invention, and Figs. 4 to 7 are the joints of the conventionally joined hollow frames. FIG. 3 is a sectional view showing the structure. 1... FRP hollow divided body 2... Overhanging part 3... Overlay part 4.
... Lightweight resin concrete 5 ... Molding mold 6 ... Adhesive tape with one side subjected to mold release treatment 7 ... Overhang plate 8 ... Flange portion 9 ... Connection bolt 10 ... Joint surface Processed part 11... Thickened part for increasing bonding area.

Claims (1)

[Claims] 1. In an FRP hollow frame formed by overlapping two hollow divided bodies, the ends of the hollow divided bodies have (i) an overhanging part extending toward the center of the hollow frame, and (ii) a hollow It has a band-shaped cut along the outer surface of the frame, and has two
When the two hollow divided bodies are joined, an overlay part is provided so as to completely fill the recess formed by the notch of the two hollow divided bodies so as not to cause unevenness in the hollow frame. hollow frame. 2. When molding the FRP hollow divided body, a tape-like material is attached to a portion corresponding to the notch of the mold for molding the hollow divided body to mold the hollow divided body according to claim 1;
2. The hollow frame according to claim 1, wherein the hollow divided bodies are then overlapped before or after peeling off the tape-like material, and an overlay portion is embedded in the recessed portion where the tape-like material was present to integrate the hollow frame. molding method.