Molding device for forming a socket end on a plastic pipe

摘要

For the purpose of making a joint socket comprising at least two portions, namely a portion for receiving a plastic pipe end and another portion into which a rubber ring is fitted, a device for heating and softening a plastic pipe end and enlarging the radius of the softened pipe end to twice its size which includes, an inwardly slanted portion between a first outwardly slanted portion and a second outwardly slanted portion whose radius becomes smaller as it comes nearer to the front end thereof. As the result, the frictional resistance between an improved core and the radius enlarged softened pipe is reduced to a value which enables the device to be operated such that wall-thickened sockets can be made without loss of wall thickness subsequent to the radius enlarging process. The core for forming a molding space includes the first outwardly slanted portion, the inwardly slanted portion and the second outwardly slanted portion and which are necessary to perform the method can be expanded and shrunk so as to pass through the small and large radius portions of the molded socket and has a self-locking mechanism capable of resisting the resistance caused between the forcedly fed pipe and the core.