| 摘要 |
In each of radial grooves 52 which are formed on a sealing disc portion 34 of a packing 10 , low strength portions 64 are formed within a predetermined range from the center of the sealing disc portion 34 by decreasing the thickness of each of thin portions 62 by deeply cutting each of the radial grooves 52 . When the center of the sealing disc portion 34 is pressed by the pressing means, splits are formed at the low strength portions 64 , and extend to curved grooves 54 and circumferential grooves 56 . As a result, it is possible to obtain a plugging member in which a draining port can be opened wide with a small amount of pressing force.
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