Federal-Mogul Corporation

William E Clark

John D Butler

A method for manufacturing bidirectional hydrodynamic polytetrafluoroethylene shaft seals. A flat annular wafer of polytetrafluoroethylene of constant thickness is coined at an annular inner portion adjacent the inner periphery to provide first and second circular ribs and a series of straight segmental ribs, each of which extends tangential to the inner side of the inner rib, thereby intersecting the inner rib, the crest of the straight ribs projecting out further than the crest of the inner rib. Then the annular inner portion is formed into a generally frustoconical shape, whereby the straight ribs appear as curved ribs. The frustoconical portion is flexed on installation on a shaft to be generally cylindrical from at least the outer rib to the inner periphery.

Method for manufacturing bidirectional hydrodynamic

A method for manufacturing an oil seal element from polytetrafluoroethylene and the like. A tubular billet of polytetrafluoroethylene or the like is provided with inner and outer cylindrical surfaces approximating the desired diameter, and an end wall is faced off perpendicular to the cylindrical surfaces. A series of washers of a desired thickness is then sliced from the billet. In one form of the invention, each washer may next be cut to exactly the desired inner and outer diameter, and, simultaneously, spiral grooves or other hydrodynamic shapes may be formed on one face of each washer, leading from the inner periphery of each washer for a desired distance toward the outer periphery; this may be done by using a novel blank-pierce-coining die that both trims the seal and coins the groove between a pair of metal surfaces at very heavy pressure to permanently deform the material in these surfaces. Each washer is formed under pressure to permanently deform the radially inner portion thereof to a frustoconical shape, this operation preferably being carried on during assembly of the seal. The assembled seal may be held on a shaft-size mandrel during application of a coating to the metal case.

Apparatus for making polytetrafluoroethylene sealing elements with

A method for manufacturing an oil seal element from polytetrafluoroethylene and the like. A tubular billet of polytetrafluoroethylene or the like is provided with an outer cylindrical surface of the desired diameter and an inner cylindrical surface approximating but slightly smaller than the desired diameter, and an end wall is faced off perpendicular to the cylindrical surfaces. A series of washers of a desired thickness is then sliced from the billet. The flat washer is then first assembled with a metal case and then a desired hydrodynamic shape, such as a spiral groove, is coined in. Preferably, the inner pierce is completed at this time. Each washer may then be formed under pressure to permanently deform the radially inner portion thereof to a frustoconical shape. The assembled seal may be held on a shaft-size mandrel during application of a coating to the metal case.

Growing community of inventors

Chelsea, MI, United States of America

William E Clark