Device for forming a longitudinal seam of a tubular film

摘要

Equipment for forming a longitudinal seam (2) along a tubular film (3) includes a former (5) for wrapping flat film (4) around a forming tube (6), a film transporting unit (7) and a seam welder (17) comprising two opposing continuous sealing belts (14, 15) which grip both film edges (13). At least one belt (14, 15) is heated. Pref. the equipment is used in a vertical tubular bag prodn. machine with the welding unit (17) on the forming tube (6). Both sealing belts (14, 15) may be heated and run in a plane either tangential to the forming tube (6) or radial to the tube (6), in the latter case one sealing belt (14) is inside the forming tube (6), the other outside. Pressure can be applied to the seam at the sealing belts (14, 15) by spring-load plates which are heated.