JPS6059855B2 - Bending method for FRP outer shell structure with core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface skin processing method for an FRP outer shell structure that is bent and formed using fiber reinforced plastic (hereinafter abbreviated as FRP) as an outer shell strength member, such as a tennis racket frame. , a rod-shaped molding material is bent in the width direction by wrapping prepreg, which is an uncured FRP outer shell molding material, around the outer periphery of a core material made of foamed synthetic resin or the like and having a rectangular cross-section with a thickness smaller than the width. Then, when mold-fitting into a desired mold and subjecting it to heat-pressure hardening treatment to process the surface into the shape of, for example, a tennis racket frame, a strip-shaped reinforcing core material is interposed adjacent to the rod-shaped molding material in the width direction. By doing so, it is possible to easily process the surface skin of the rod-shaped molding material, and to make the strength distribution uniform over the entire length, thereby improving workability and productivity.

Conventionally, in manufacturing this type of FRP outer shell structure, for example, an FRP tennis racket frame, as illustrated in FIGS. 1 and 2, it is usually made of foamed synthetic resin such as hard foamed urethane resin. A rod-shaped molding material 3 of a predetermined length, in which prepreg 2, which is an uncured FRP outer shell molding material, is wound and encapsulated around the outer periphery of the core material 1, is molded into a desired racket frame shape, and then molded into a mold ( (not shown), and heat-pressure hardening molding is performed to form a surface skin.

However, such a conventional tennis racket frame, as illustrated in FIG.
In other words, if the cross-sectional shape of the core material 1 is such that the thickness T is larger than the width W, it is easy to curve the width direction side and there is no problem.
On the other hand, if you try to wrap an item whose thickness T is smaller than the width W in the width direction, it will tend to bend toward the side where the bending strength of the core material 1 is weaker, and as a result, the surface portion of the rod-shaped forming material 3 will bend. Not only does backlash occur, making it extremely difficult to fit the mold into the mold, but due to this backflow phenomenon, the center line of the rod-shaped molding material is aligned along the length direction and perpendicular to the surface skin direction (three thickness directions). As a result, the strength distribution of the molded racket frame, especially at the ball-hitting portion of the frame, becomes uneven, which tends to cause problems such as unstable performance characteristics. This invention eliminates the above-mentioned conventional drawbacks, and will be explained based on the embodiments shown in FIG. 3 and subsequent figures.

FIG. 3 shows a first embodiment according to the present invention, in which 10
is a rod-shaped molding material that is bent into the shape of a desired tennis racket frame, for example, with a core material 11 made of foamed synthetic resin and a prepreg sheet 12 that is an uncured FRP outer shell molding material on the outer periphery. The core material 11 has a rectangular cross-section in which the thickness T is smaller than the width W, and the width direction side thereof is the bending direction.

The rod-shaped molding material 10 includes a strip-shaped reinforcing core material 13 having a width corresponding to approximately the thickness T of the core material 11 made of a thin plate such as ABS resin or wood, which is larger than the bending and rigidity of the core material 11. are interposed adjacently to the outside in the width direction of the core material 11, that is, parallel to the outer peripheral side surface in the bending direction, and the core material is arranged so that the width direction of the strip-shaped reinforcing core material 13 is perpendicular to the bending direction. 11 on the outer side surface in the width direction. In the above-mentioned first embodiment, the strip-shaped reinforcing core material was placed closely adjacent to the outer circumferential side of the core material, but the strip-shaped reinforcing core material itself was also wrapped with prepreg and the prepreg was wrapped between them. Alternatively, the strip-shaped reinforcing core material may be attached to one side of the inner circumferential surface of the core material, or to both the inner and outer circumferential surfaces of the core material.

Furthermore, FIG. 4 shows a second embodiment according to the present invention,
In a product in which the core material 11 constituting the rod-shaped molding material 10 has a width W1 in the width direction and is divided into a plurality of pieces, for example, two pieces, each having a predetermined thickness T, a core material 11 constituting the rod-shaped molding material 10 is divided into a plurality of pieces, for example, two pieces, with a width W1 in the width direction. This shows an example in which a core material 11 of a predetermined width W is formed with a strip-shaped reinforcing core material 13 interposed therebetween. Therefore, according to the above structure, the rod-shaped material for forming an FRP outer shell is wound and encapsulated around the outer periphery of the core material, the thickness of which is smaller than the width. When bending into a shape,
A thin strip-shaped reinforcing core material having a higher bending rigidity than the core material is interposed adjacent to the width direction of the core material, and the width direction of the strip-shaped reinforcing core material is positioned perpendicular to the bending direction. Therefore, the rigidity of the rod-shaped forming material against the bending moment around the width direction side axis (X-axis) is greater than the rigidity against the bending moment around the thickness direction side axis (Z-axis). A plane between the width direction (X-axis) and the circumferential direction (Y-axis) (
When bent on the X-Y plane), it is possible to reliably prevent the occurrence of curling, and the bending process is facilitated, resulting in excellent workability and productivity.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the bent state of a tennis racket frame, which is a conventional FRP outer shell structure, and Figure 2 is a diagram of Figure 1A.
- A partially enlarged cross-sectional perspective view of the rod-shaped molding material taken along line A;
FIG. 3 is a partially enlarged sectional perspective view of a rod-shaped molding material showing a first embodiment of the present invention, and FIG.
It is a partially enlarged cross-sectional perspective view of a rod-shaped molding material showing an example. 10... Material for rod-shaped molding, 11... Core material, 12... Material for FRP outer shell molding, 13.
...Band-shaped reinforcing core material, T...Thickness, W...
····width.

Claims (1)

[Claims] 1. A rod-shaped molding material is formed by wrapping an uncured FRP outer shell molding material around the outer periphery of a core material with a rectangular cross-section whose thickness is smaller than its width, and the rod-shaped molding material is rolled on the width side. In bending the rod-shaped forming material, a strip-shaped reinforcing core material having greater bending rigidity than the core material is interposed adjacent to the width direction, and the width direction of the strip-shaped reinforcing core material is directed in the bending direction. A method of bending an FRP outer shell structure characterized by orthogonal positions.