Abstract: Apparatus for making a tubular plastic sheath having one or more imperforate panels around the periphery of the sheath with intervening plastic net connecting the imperforate panels, the apparatus including an extruder, perforating means and stretching means, the improvement being extrusion means to form bands of different thickness asbout the sheath the perforation means being positioned such as to perforate only bands of one thickness.
Abstract: Helical plastic members are formed by rotating an extrusion die while extruding a filament in a generally horizontal direction just above a tank of liquid. The plastic helix so formed is cooled and solidified in the liquid. A mandrel in the liquid can be used to guide the helix downwardly, and the helix is removed from the tank with extraction rollers. As a variation, the tank can rotate relative to a fixed extrusion nozzle which extrudes the plastic horizontally just above the rotating liquid in the tank.
Abstract: Method of manufacturing helical members from a synthetic plastic material comprises the step of leading the extruded material while still deformable along the helical path and permitting it to harden while retained in that path. The invention also comprises a machine for carrying out this process and the article produced thereby.
© 2024 Justia
