| 摘要 |
PURPOSE:To obtain a hollow O-ring having a uniform wall thickness by disposing, in the hollow part of the O-ring, a fiber thread applied with a blowing agent which foams and generates gas upon molding by vulcanization, so that the foaming is carried out uniformly over the whole section of the hollow part. CONSTITUTION:A cylindrical unvulcanized cylindrical rubber tube 4 is inserted therein with a fiber thread 3 which is adhered or impregnated with a blowing agent, and then, is formed into a continuous hollow part 21 having the thread 3 inserted therein by bonding both ends 4a of the rubber tube 4 together. The thus obtained annular rubber tube 4 is vulcanized for molding so that gas is simultaneously generated from the blowing agent, and therefore, there is obtained a hollow O-ring 1 in which gas is charged and which has a predetermined shape. With this method, the foaming is uniformly carried out over the whole section of the hollow part 21 since the blowing agent is applied to the thread 3, thereby such a disadavantage that the wall thickness of the O-ring is locally thinned caused by the locally aggregative foaming of the blowing agent within the hollow part 21, may be eliminated. |
