Process for laser beam welding of plastic parts

摘要

A laser energy absorbing and heat generating material(4.1) is located at an interface layer(2.1) between two plastic parts(1.1,1.2), one(1.1) of which transmits laser light. The two parts are pressed together(P) and a laser beam(11.1) directed at the laser-transparent part so that the plastic parts are partially melted at the interface layer and on cooling form a welded seam between both parts. Preferred Features: For welding together two or more plastic parts several lasers are employed which produce beams with different wavelengths covering a specific range. Energy converters for absorbing the different wavelengths are placed at each interface between the plastic parts and the latter are pressed together. All but the final plastic part can transmit laser light of at least one wavelength and the final part has a specific transparency to laser light. The interfaces can be irradiated simultaneously or successively with the lasers to effect partial melting at each interface and formation of a weld line. An energy converter which absorbs different wavelengths is placed at at least one interface and the plastic parts at this interface are irradiated by two or more laser beams with the different wavelengths to effect melting. Interface layer thickness and/or absorption coefficient of the energy converter and/or thickness and/or duration of the laser energy are chosen so that only simultaneous irradiation by two beams effects heating and melting of the plastic parts. Energy converters are positioned at the rear face of an irradiated plastic part. Penetration depth of a welded seam depends on pressure applied to the plastic parts.