| 摘要 |
PROBLEM TO BE SOLVED: To prevent impairment of a sealing function which is caused by each claw pushed over sidewise, by forming wall parts, which fill in empty spaces between the claws forming a claw group, onto the internal face of a head part. SOLUTION: Because wall parts 22 formed on the internal face of a head part 2 fill in empty spaces between claws 41 forming a claw group 4, such a possibility that the claws 41 are pushed over sidewise due to the contact of the claws 41 with the wall parts 22 is kept from occurring (sidewise-fall prevention effect). Further, because each claw 41 has an unfolded-fan shape that becomes wider from the position near its leading end toward its root part, such an unfolded-fan shape of each claw 41 helps to make it difficult for the claw 41 to be pushed over sidewise. Thus, a combination of the sidewise-fall prevention effect of the walls 22 and the unfolded-fan shape of the claws 41 eliminates the occurrence of such a possibility that the claws 41 are pushed over sidewise. |
