Apparatus for welding sheets (3a,3b) of themoplastic material together along proximate edges including a supporting frame (25), a pair of joining rollers (11,13) mounted on the frame and forming a nip (12) with an axis parallel to the axes of the rollers, a motor (23) to drive at least one of the rollers,...http://www.google.es/patents/US4713131?utm_source=gb-gplus-sharePatente US4713131 - Apparatus and method for ultrasonically joining sheets of termoplastic materials
Apparatus and method for ultrasonically joining sheets of termoplastic materials
