Patent ID: 6328309
Filing Date: 2001-12-11
Classification: B29C,F16L,Y10S

Abstract:
A method of installing a gasket in a socket end of a thermoplastic pipe which is used to form a pipe coupling, the method comprising the steps of:providing a mandrel with an inner end and an outer end and having a generally cylindrical outer working surface;installing a gasket at a first circumferential position on the outer working surface, the gasket having at least selected surfaces coated with a spray-on anti-friction coating wherein the spray-on anti-friction coating is applied by spraying on a dry powder followed by heating the powder to cause it to be fixed;providing a retention member at a second circumferential location on the mandrel nearer the inner end of the mandrel, the retention member abutting the gasket in a normally extended position but being retractable to a retracted position in a subsequent manufacturing step;heating a socket end of the thermoplastic pipe;forcing the heated socket end of the thermoplastic pipe over the working surface of the mandrel and over the gasket with the retention member being in the extended position, whereby the heated socket end of the thermoplastic pipe flows over the gasket to form a retention groove for retaining the gasket and again contacts the working surface of the mandrel;cooling the heated socket end of the thermoplastic pipe;retracting the cooled socket end of the thermoplastic pipe and the retained gasket from the working surface of the mandrel.