Method for producing a rupture line in a multilayer air bag cover by using a laser

摘要

High density base layer (1), which is complemented by a support layer (2) and a decorative layer (3), is cut away by laser. Its (1) removal is complete along the line of intentional rupture, i.e. excavations of the base layer overlap to form a slot. The width (b) of material removal from the base layer, exceeds the laser beam diameter (a). Through the penetrations made in the base layer (1), the laser forms spaced blind holes or microperforations in the layers below. Gases evolved, escape through the penetrations. The width (b) of the initial penetrations is more than twice the laser beam diameter (a). Individually round, of diameter (b), the penetrations in the base layer collectively form a slot. Penetrations are alternatively produced by a milling- or drilling tool. The laser beam energy density profile has a top-hat- or annular configuration. It is alternatively gaussian, the laser beam incidence on the base layer being defocused. During manufacture of the air bag covering, a barrier layer is introduced between the support layer (2) and the base layer (1). This restricts energy introduction into the support layer during treatment of the base layer. The barrier layer material is gas-permeable.