VORRICHTUNG ZUR BILDUNG EINES ROHRES.

摘要

A flexible heat-sealable web (w) is shaped continuously into a tubular cross-sectional shape, eg. as an intermediate stage in the production of infusion bags comprising severed and sealed lengths of the tubular-shaped web. The web is drawn along a shaped shoe (2) and side margins of the web are folded over opposite sides of the shoe by rollers (34) and fingers (36,38) to place the opposite side edges of the web in overlapping relationship against the shoe. The overlapped edges pass between a roller (20) mounted in the shoe and an external heated roller (56) and are pressed together by the rollers to lap weld the edges together as the web travels along the shoe. The shoe continues to form the web downstream of the welding station into a flattened tube.