| 摘要 |
A new tubular sealing device made of soft elastic material and having a bore circular in cross section and extending axially therethrough, the sealing device including an inverted frustoconical outer periphery and an inner peripheral surface defining the bore, the inner peripheral surface having a constricted portion of the smallest diameter, an upper portion extending upward from the constricted portion with a progressively increasing diameter to define a tapered bore section and a lower portion extending downward from the constricted portion to define a bore section having a larger diameter than the constricted portion.
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