METHOD AND APPARATUS FOR WELDING A COVERING FOIL AND A SUPPORT OF THERMOPLASTIC MATERIAL

摘要

The sealing of a cover sheet (22) on one side of a rim (21) of a container (20) made of thermoplastic material is performed by bringing a heating electrode (24) onto the cover sheet along a strip located above and at least on one side of a contact zone between the rim of the container (20) and a bearing piece (23) applied against the other side of the rim (21), and in pressing towards each other the bearing piece and the heating electrode in order to cause the plastic to melt and to form a weld bead on one side of the contact zone. The upper edge of the bearing piece has rounded-top shape (23a) and is pressed against the electrode until the cover sheet breaks in order simultaneously to weld the latter and the container and to cut them along the weld bead.