| 摘要 |
PURPOSE:To enhance the pressure resistant efficiency of a reinforcing layer, by making the relative positions of a plurality of reinforcing layers positioned at the end part of a rubber bag in a contracted state equal to that in the expanded state of said rubber bag. CONSTITUTION:The reinforcing layers 12, 13 in the end part of a rubber bag are not almost or entirely shifted since the folded-back parts 17b, 18b of reinforcing sheets are adhered to each other by the viscosity of unvulcanized rubber when folded back. From this, the rubber bag becomes a state such that the inside reinforcing layer 12 is compressed in the circumferential direction or a state such that the outside reinforcing layer 13 is pulled in the circumferential direction or the state generating both of these phenomena and, therefore, the relative positions of the inside and outside reinforcing layers 12, 13 in the end part of the rubber bag in such a state that the rubber bag is in a flat state are kept without applying force to the reinforcing layers 12, 13 even when the radius of curvature at the end part of the rubber bag becomes extremely large by the expansion of the rubber bag. As a result, the tensile force due to the pressure in a fluid filling space is equally applied to both of the reinforcing layers 12, 13 when the rubber bag is expanded and the pressure resistant efficiency of the reinforcing layers can be enhanced.
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