Piston or plunger and a method for making the same

Abstract

A piston or plunger and a method for making the same A piston or plunger comprises a piston body and a sealing member. The piston body is preferably made from metal by moulding, such as casting or pressure moulding and sintering. The sealing member is made from a thermoplast, such as polytetrafluoroethylene (PTFE). The piston body has an outer or an inner peripheral surface part in which axially extending depressions or grooves are formed during moulding of the piston body. The axially extending grooves may be open at one or at opposite ends. An annular sealing member blank is applied to the peripheral surface part and is deformed and forced into tight engagement with the peripheral surface part and into the grooves or depressions formed therein. The sealing member formed is also exposed to a heat treatment. The piston or plunger having the sealing member applied to an outer peripheral surface part may, for example, be used in shock absorbers. Alternatively, the sealing member may be applied to an inner peripheral surface part. In such case the piston or plunger may be used as a stationary sealing device for encircling and sealingly guiding a reciprocating shaft or a piston rod.

Dependencies are inferred from the claim text.