Abstract: 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.

Abstract: 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 method of 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 method to be carried out such that wall-thickened sockets can be made without loss of wall thickness subsequent to the radius enlarging process.

Abstract: A synthetic resin pipe joint having front and rear inclined walls defining a packing holding annular groove is provided with softness and elasticity sufficient to cause flattening deformation on impingement with a pipe contained therein, and expansion of a gap between this pipe and the inner circumferential face of the pipe joint is effectively prevented. On overall flattening deformation of the pipe joint, the front and rear inclined walls are similarly deformed and a packing contained therein is stably deformed with the deformation of the inclined walls without causing distortions in the packing. Because of such high elasticity and flexibility as not possessed by rigid joints, a pipe line can be effectively constructed by using this pipe joint.

Abstract: A method of molding a socket part on a synthetic resinous pipe end is disclosed. The socket part is for use in the connection of synthetic resinous pipes and is provided with a filler ring for filling a space created by a spigot pipe end, the inclined surface at the interior of the socket part, and a virtual inner surface formed by the two connected pipes. In addition, the filler ring fulfills a function in the capacity of a stopper which regulates the insertion length of the spigot pipe. For the purpose of its being retained in the socket part, the filler ring to be employed should have its external diameter be slightly larger than the internal diameter of the part which has been molded as the socket part, and is held through the medium of a holding means which is maintained concentrically with the core mold.

Abstract: A pipe joint for connecting heterogeneous pipes is disclosed, wherein the one end, which is provided with a metallic male screw, forms a connecting portion with metallic wares, and the other end, which is molded of synthetic resin, constitutes another connecting portion with synthetic resinous goods. A nut-shaped tightener part, which is needed in time of the joint's being screw-connected with metallic pipe, is formed integrally with the metallic material which constitutes the male screw, being exposed high on the external periphery of the pipe joint, while the synthetic resinous material, which forms the synthetic resinous connecting portion, as being extended, is adhered all over the internal periphery of metallic material to be watertightened.