One-piece, flexible, plastics bellows prodn. - by sliding widened tubular film over spaced-apart rings, heat-shrinking film to fit on rings and contract to bellows shape between rings

摘要

Mfr. of plastics, flexible, bellows comprises inflating or otherwise expanding a plastics tubular film or hose to up to six times its initial dia.; slipping it over spaced-apart rings; and then causing the tube to shrink by application of heat. In this way the tube sits tightly upon the rings whilst shrinking to a comparatively smaller dia. in those zones intermediate between adjacent rings, thus forming a bellow shaped, one-piece structure. The process enables bellows to be made in one piece without recourse to comparatively expensive moulds. The rings may be arranged e.g. in an acurate line so that curved bellows can be mfd. The rings are axially displaceable.