Top cover for instrument panel with seamless air bag door and method of manufacture

摘要

An instrument panel top cover with a seamless breakaway air bag door made as a unitary composite from multiple layers of plastics by extruding a parison with inner and outer layers of different recyclable plastics having different physical characteristics but which are from the same plastics family. The parison is injected and expanded with low pressure gas and forming dies with door scoring tools are closed thereover. The plastics will resultantly conform to the shaping surfaces of the dies to form the composite while the perimeter of the air bag door is scored. A quantity of the plastic material interior of the door score lines is removed after the top cover is removed from the dies so that a seamless or hidden door is provided that can readily break open at the peripheral scores to augment air bag operation when the air bag is triggered.