Weak line creation in an air bag cover of a vehicle instrument panel involves simultaneous cutting of weak line in foamed, fiber reinforced supporting layer and facing layer

摘要

A supporting part(16) is produced in a foamed, glass fiber reinforced polyurethane. A facing layer(18) is then applied onto the supporting layer. Simultaneously a deliberate weak line is formed in the support and the facing layer by inserting a cold blade(24) from the rear side of the support. Blade cutting depth is set so that the blade does not penetrate a decorative surface layer(20). Material thickness remaining in the weak line area is 0.45-0.5mm. The thickness of the supporting layer(16) and facing layer(18) is 7.8-8mm. Surface layers may have a layered construction which includes a knitted fabric forming a spacer layer(19) facing the supporting layer. Weak lines may be formed by cuts which alternate with non-cut areas along the weak line.