Injection moulded plastic piston for dispenser cylinder

摘要

A piston (1), for a dispenser cylinder, consists of plastics and is non-detachably joined to the spherical end (3) of a piston rod (4), the novelty being that the spherical end (3) is surrounded by a cup (2) which is injection moulded in the piston (1). Also claimed is a process for prodn. of the above piston, involving: (a) providing the spherical end (3) of a piston rod (4) with a cup (2); (b) placing the piston rod (4) in an injection moulding tool without direct contact between the piston rod and the tool cavity; (c) injecting plastics into the tool so that the cup is gripped by the plastics; and (d) removing the finished piston from the tool.