Moulding of a plastic steering wheel integral with a metal frame by injecting a propellant to form a cavity

摘要

A steering wheel (1, fig 1) has a rim comprising a metal frame 6 with an integrally moulded plastics coating (9, fig 2) which has an internal cavity 11. The cavity 11 is formed by initially injecting hot plastics material into a substantially vertical mould (20, fig 4) and subsequently blowing air, another gas or water through an injector 27 into the lower part of the mould after some of the plastic adjacent the mould walls has started to cool, to lift a still molten core of plastic against a gravitational force. Alternatively the mould may be in a centrifuge. The injector 27 may be retractable, or a spoke terminal. The moulded plastic may be covered with a softer outer moulding, leather or wood. The frame has spokes (5, fig 1) extending outwardly from a boss (3, fig 1). Thus weight is minimised while recycled material may be used.