Fully automatic welding of two thermoplastic sections, by passing laser beam through one of them, first absorbs energy at second surface then conducts it to melt both surfaces, which are fused together under pressure

摘要

A beam of laser energy passes through a cross section (39) to heat and plasticize a second cross section, which reaches a working temperature. Heat from the second surface is conducted back to the first cross section, plasticizing it, and causing it to reach a similar temperature. The energy beam, heating only a part of the join (a field) at any one time, is advanced relative to it. An independent claim is included for the corresponding laser welding equipment. Preferred features: Working temperature is reached by first preheating as described, then making repeated passes. The transient heating process is further detailed, exchanging heat according to the foregoing principles, until both surfaces of the joint (41, 42) are molten, and weld together. It will be noted that references to heating of surfaces, necessarily implies limited heating to some finite depth. The cross sections (39, 40) are pressed together, at the latest just before reaching the working temperature, but preferably during preheating. Pressure is applied until after bonding is complete. A process of heating whilst holding at an acute angle is described, following which the surfaces are moved relatively, up to stops and under pressure, where they cool, completing bonding. Additional features of the equipment used for the process, include its motorized optical system, and the clamping system, which is operated automatically in accordance with the principles described.