JPS6049419B2 - 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 made of foamed synthetic resin or the like having a rectangular cross-sectional center material whose thickness is smaller than its width is wrapped and encapsulated with uncured FRP outer shell molding material Preprec, and then bent in the width direction. When mold-fitting into a desired mold and subjecting it to heat-pressure hardening treatment, for example, when processing the surface into the shape of a tennis racket frame, a plate-like auxiliary material is attached to the outside surface of the rod-shaped molding material in the width direction. By attaching it, 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, foamed synthetic resin such as hard foamed urethane resin is usually used. 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 center material 1, is skinned into a desired racket frame shape. The surface skin is processed by fitting into a mold (not shown) and performing heat-pressure curing molding. However, in such a conventional tennis racket frame, as illustrated in FIG. There is no problem as it is easy to curve the widthwise side, but if you try to curve the widthwise side of a piece whose thickness T is smaller than the width W, the core material 1 will tend to bend toward the side where its bending strength is weaker. However, as a result, twisting occurs in the surface skin part of the rod-shaped molding material 3, which not only makes it extremely difficult to fit into the mold, but also causes the center line of the rod-shaped molding material to bend in the direction of the burr. The strength distribution of the racket frame after molding becomes uneven, especially in the ball-hitting part of the frame, and the performance characteristics become unstable. This could easily lead to inconveniences such as

This invention eliminates the above-mentioned conventional drawbacks, and will be described below based on the illustrated embodiments.

As shown in FIG. 3, numeral 10 in the figure is a rod-shaped molding material that is processed into a desired tennis racket frame shape, and an uncured material is placed on the outer periphery of a center material 11 made of foamed synthetic resin. The core material 11 has a structure in which a prepreg sheet 12, which is a material for forming an FRP outer shell, is wound and encapsulated, and the core material 11 has a rectangular cross section in which the thickness T is smaller than the width W, and the widthwise side thereof is oriented in the bending direction. I have to. The rod-shaped molding material 10 is provided with a plate-shaped auxiliary material 13 made of a thin plate such as ABS resin or wood, which has a bending rigidity greater than the core material 11 with a thickness T, on the outer side in the width direction, that is, the bending rigidity is greater than the bending rigidity of the core material 11. The plate-shaped auxiliary material 13 is integrally attached to the outer peripheral side surface in the bending direction, and is arranged so that the width direction of the plate-shaped auxiliary material 13 is orthogonal to the bending direction. Therefore, according to the above configuration, a rod-shaped molding material in which an uncured FRP outer shell molding material is wound and encapsulated around the outer periphery of a core material whose thickness is smaller than its width is placed on the desired width direction side. When bending into the shape of Since it is positioned perpendicular to the bending direction, the width direction side axis (X
The rigidity against the bending moment around the axis (axis) is greater than the rigidity against the bending moment around the thickness direction axis (Z-axis), so the rod-shaped forming material is When bent on the plane (X-Y plane), it is possible to reliably prevent the occurrence of twisting, and moreover, 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 shell structure, and Figure 2 is a diagram similar to Figure 1.
- Partially enlarged cross-sectional perspective view of the rod-shaped molding material taken along line ■,
FIG. 3 is a partially enlarged cross-sectional perspective view of a rod-shaped molding material according to an embodiment of the present invention. 10... Material for rod-shaped molding, 11... Core material, 12... Material for FRP outer shell molding, 13.
...Plate-shaped auxiliary 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 placed on the widthwise side. When bending, a plate-shaped auxiliary material having greater bending rigidity than the core material is attached to the outer surface side in the width direction of the rod-shaped forming material, and the width direction of the plate-shaped auxiliary material is oriented in the bending direction. A method of bending an FRP outer shell structure, which is characterized by orthogonal positioning.