Patent ID: 7919036

Claim:
A process for constructing a preweakened automotive interior trim piece comprising an instrument panel covering an air bag installation, said preweakening extending in a predetermined pattern enabling formation of an air bag deployment opening in said instrument panel by pressure exerted by an air bag deploying from said air bag installation mounted on the inside of said trim piece, said process including the steps of: constructing said instrument panel with a thin pliant plastic outer cover layer defining an outer surface extending smoothly and uninterruptedly over said predetermined pattern; preweakening said constructed instrument panel by directing a laser beam at an inner surface of said instrument panel and along said predetermined pattern so as to produce a scoring therein partially penetrating an inner surface of said outer cover layer along said predetermined pattern; and said preweakening step including controlling said scoring by said laser beam so as to cut a series of repeating spaced apart deep scoring penetrations extending partially into the inside of said trim piece cover with intervening uncut material between said deep scoring penetrations thereby forming a varying depth laser scored groove in said outer cover layer which has a lower resistance to tearing along said predetermined pattern by the pressure exerted by said deploying air bag because of the presence of said deep scoring penetrations while said intervening uncut material strengthens said outer cover layer to reduce any tendency for preweakening said pattern to become visible from said outer surface prior to air bag deployment or to develop cracks in said outer cover sensing the remaining thickness of said instrument panel outer cover layer beyond said scoring during said laser beam scoring, and controlling said laser beam scoring in correspondence to said sensed remaining thickness so as to maintain a predetermined minimum remaining thickness of said instrument panel outer cover layer beyond said scoring to avoid cracking along said pattern.