Heated tool, esp. metal band, for welding of plastic, e.g. polyethylene@ - comprises flexible band which deflects to give reduced pressure at edges, improving weld strength and avoiding penetration and extrusion

摘要

Process and tool for welding plastics film in which the heated tool (16, 22, 24) is applied against the film (10, 12) with progressively smaller pressure towards its edge(s) (26, 28). A welding band may be constructed of a lower narrow central support core (2) and a thin wide upper band (24) which bows elastically under pressure applied through bar (22). USE/ADVANTAGE - Hot tool lap welding of plastics films, e.g. PE, redn. of pressure at the edges avoids the usual depression and extrusion of melt at the edges of the weld and poor weld properties leading to splitting of seams, e.g. if massive goods are dropped into a pre-sealed bag.