1. Field of the Invention
The present invention relates to a resin composite structure obtained by integrally bonding fiber-reinforced thermoplastic resin composite members containing discontinuous fibers. The present invention also relates to a method for producing such a resin composite structure.
2. Description of the Related Art
A fiber-reinforced thermoplastic resin composite (hereinafter referred to simply as a resin composite) is a material containing fibers such as glass or carbon fibers impregnated with a thermoplastic resin. In recent years, such a resin composite has been studied as a material for a component of a car body (such as a floor or a monocoque component).
In general, the car body component has a large size. Therefore, in order to produce the entire component in one molding process, a large scale molding apparatus is needed to apply a large load during the molding process. Such a large scale molding apparatus is expensive and consumes a great amount of power during the molding process. Therefore, this type of molding apparatus is disadvantageous for mass production in terms of its high facility cost and high running cost.
A large component can be obtained by connecting a plurality of members that have been prepared separately. However, in the case that such separate members are connected mechanically using nuts and bolts or rivets (i.e., so-called metal fasteners), a boring operation and a fastening operation are required, thereby resulting in high operating costs. Furthermore, the weight of the component is increased due to the metal fasteners. In addition, in this case, electrolytic corrosion occurs at a contact portion between the reinforcing fibers and the metal fasteners. Further, it may be necessary to take countermeasures in response to different coefficients of thermal expansion of the materials.
The members may be connected by other known processes such as thermal welding, vibration welding, ultrasonic welding, or laser welding. However, such processes do not produce a sufficient welding strength.
In a method proposed in Japanese Laid-Open Patent Publication No. 11-090986, the members first are heated and melted such that the reinforcing fiber is partially exposed on the surface of the connection, and thereafter, the melted members are press-molded and welded. Japanese Laid-Open Patent Publication No. 11-090986 describes that the connection obtained by this welding method has an excellent appearance and exhibits a high welding strength.