MANUFACTURE OF VALVE

摘要

PURPOSE:To render removal of the unnecessary part of a protection film needless, and enable the manufacture to be conducted extremely efficiently in reducing the defective rate by mounting a preliminarily punched out protection film on first vulcanized rubber, and then giving second vulcanization thereto. CONSTITUTION:Unvulcanized rubber is injected into the seal setting part 21 of a valve main body 2, and first vulcanization is effected for manufacturing the valve main body 2 provided with first vulcanized rubber 9. In this instance, the first vulcanized rubber 9 is set the thickness 91 of the protection film aside on the seal setting part 21. On the surface of the first vulcanized rubber 9, no flashes occur because it is not subjected to the complete vulcanization yet, moreover, since filled in the seal setting part 21 by remaining only the thickness 91 of the protection film 31, it is not pushed out on the upper surface of the valve main body. On the first vulcanized rubber 9, the protection film 31 is mounted which is formed in the upper surface configuration of the sealing part beforehand, and a press mold 7 is put thereon for effecting vulcanization in order to form the sealing part 3. In this manner, inasmuch as the first vulcanized rubber is not pushed out on the valve upper surface and no flashes exist thereon, the protection film never involves air bubbles and also never discolors, as a result, adhesion can be performed readily.