Radiator water box made of fibre reinforced resin and method for producing same

PURPOSE: To make a radiator tank of fiber-reinforced resin sufficiently resistant to high pressure, relating to one set at the inlet or outlet of cooling water for a radiator core, by orientating the reinforcing fiber in parallel to a section breadthways across the tank. CONSTITUTION: For an upper tank 11 polypropylene in a molten state, which contains glass fiber in single form, is injected into a cavity 17 through a resin- injection hole 18, that is, the molten resin is made to flow into the cavity 17 through a film gate 24 formed along the longitudinal side of the upper tank 11. Then the flow of the molten resin takes place in the same direction as a cross section of the upper tank 11 so that the reinforcing fiber 25 is orientated in the same direction as the cross section of the upper tank 11. This method enables obtaining a radiator tank with a high tensile strength in the orientation direction of the fiber, hence one resistant to high internal pressure.