| 摘要 |
The present invention consists of a collapsible hollow core, having a circumferentially variable wall thickness, for use in a method of forming a hollow article. The core is manufactured by extruding a hollow parison into an open core forming mould, closing this mould, expanding the parison against the inner walls of the core forming mould by injecting pressure into the parison, and opening the mould to remove the core. The core thus formed is used in a method of forming a hollow article of a resin reinforced with fibres. The method consists of winding reinforcing fibres tightly around a hollow core having a circumferentially variable wall thickness and placing the wound core in a mould. A differential pressure is then provided between the interior and exterior of the core to cause a thinner wall portion thereof to initiate collapse of the core, and this collapse is continued to an extent necessary to relax the fibres. Fluid resin is then injected into a space between the mould and the collapsed core to fill such space and impregnate and saturate the fibres with resin. The core is expanded to expel excess resin from the mould, and re-tighten the fibres. The resin is hardened and the final article can be removed from the mould. |
