1. Field of the Invention
The present invention relates to a method of manufacturing an automotive instrument panel having a concealed airbag. More particularly, the present invention relates to a method of manufacturing an instrument panel having a metal door overlying an aperture in a substrate with a molded flexible covering overlying the substrate and metal door.
2. Description of the Related Art
It is known to manufacture an automotive airbag having a seamless covering. One such device is described in U.S. Pat. No. 5,447,328, issued Sep. 5, 1995. The device teaches a hinged metal door secured to a plastic substrate. The hinge is secured to both the plastic substrate and the metal door and folds when the airbag is inflated. A deep groove directly overlying the perimeter of the metal door forms a weakened section in the covering that tears when the door is opened. An airbag door and cover of this construction is difficult to manufacture because a metal hinge must be secured to only one edge of the plastic substrate. It is also difficult to form a deep groove in the covering that directly overlies the perimeter of the metal door. The groove construction taught in the 5,447,328 patent extends almost to the surface of the plastic substrate, making it difficult to inject foam in the vicinity of the groove. It is desirable to inject a foam between the cover and the door to secure the two components without causing the foam to impede the opening of the door.
It is also known that the rapid force needed to deploy an airbag causes stress on the molded plastic substrate when the door is attached to only one edge. Various frames may be attached to the perimeter of the airbag opening to make the substrate more rigid. An example of this construction is illustrated in U.S. Pat. No. 5,393,088 issued Feb. 28, 1995. A metal frame is secured within the aperture of a plastic substrate. A door is attached to one side of the frame with a hinge. The metal frame keeps the substrate from deforming under the impact of an inflating airbag.
Finally, it is also known to secure an airbag to the underside of a substrate using a chute that partially spaces the airbag from the door. Gaps or spaces between the chute and door may allow the airbag to partially inflate behind the panel.
It is an advantage of the present invention to provide a seamless airbag covering having an unhinged door that is secured to a substrate. It is a further object of the present invention to provide an easily manufacturable method of securing the airbag covering to the substrate and door. These and other objects, features and advantages of the present invention will become more apparent to those of ordinary skills in the art upon reference to the attached drawings and following description.