FOERFARANDE FOER FRAMSTAELLNING AV EN ZONFOGFOERSLUTNING SPECIELLT PAO EN GAVELFOERSEDD VIKNINGSKARTONG

摘要

A method and an apparatus for making a fillet seam closure on folding boxes fabricated from box-board internally lined with aluminum foil and coated with a thermal plastic resin includes folding the fillet seam along a fold line, holding the areas of the fillet seam to be welded together by applying compressive forces along a line parallel to the desired weld seam and slightly spaced therefrom between the weld seam and the fold line and ultrasonically welding the fillet seam with a simultaneous application of pressure in the weld seam which gradually decreases from the weld seam center line to the edge facing the fold line to effect the displacement of the thermal plastic resin from the center line towards the edge in the formation of a V-joint. The weld is allowed to cool off and the compressor forces are maintained during the welding and the cooling operations.