| 摘要 |
PURPOSE:To contrive an improvement in a valve function by preventing breakaway of a packing, by a method wherein the packing is made to hold and position on the inner circumferential surface and a fitting part of a valve body is laid into a synthetic resin material by making the synthetic resin flow in an undercut part. CONSTITUTION:When a packing 6 is held, synthetic resin is pressed in through a gate part 16 of a stationary mold 12. The resin is protruded into a cavity 14 which is filled with the resin by spreading even to the backside of a fitting part 6a and fitting concave part 6c. A protruded stripe 17 to be formed in a mold 12 improves heat radiation effect of the resin material to be obtained after injection and reduces affection of heat to the packing 6. The resin is cooled within the cavity 14, through shrinkage force of which a core pin 13a is embraced strongly. When, therefore, a mold 13 is moved in the direction of an arrow drawn with a blanked frame, a head part 10 is moved along with the mold 13 and released from the mold 12. The packing 6 is held stably in the head part 10 obtained by injection molding in this manner through fitting between the fitting concave part 6c and a breakaway prevention protrusion edge 10a. |
