PURPOSE: To secure the configuration as well as the thickness of the socket in good accuracy by a method wherein a rubber core, the hardness of the aft end part of which is reduced than that of the other part thereof, is mounted on the land part of a tamping in such condition that it neighbors a rubber ring retaining ring and is utilized for the working.
CONSTITUTION: The rubber ring retaining ring (a) is mounted on the stepped section 11 of the tamping 1 while the rubber core C is mounted on the land part 12 thereof so as to be neighbored the ring (a). The hardness of the aft end C1 of the core C is made lower compared with the other part C2 thereof. (for example, the hardness of the aft end part C1 is Hs 50° while that of the other part C2 is Hs 90°.) The heating end of the plastic pipe P is introduced onto the tongue pin 1 and the plastic pipe section on the rubber core C is pressed by an outer form 2. The generation of the burrs of the rubber core C upon introducing the pipe may be prevented and the generation of a stress upon being pressed may be lightened by escaping the section C2 having higher hardness to the aft end part C1 side, thereby enabling to reduce the tinning of the pipe.
ITOU TAKEHIRO
ISHIHARA KATSUROU
YOSHIKAWA ATSUSHI
