| 摘要 |
<p>An oil seal (1) having a lip (4) over which a shaft (11) is inserted has a curling prevention structure on the lip (4) side. The structure effectively works when the shaft is rotated at the time of the insertion. A structure (6) for guiding expansion of the lip is provided at that portion of the lip (4) which is in contact with the shaft (11) when it is inserted, and the structure prevents curling of the lip (4) when the shaft (11) is inserted while being rotated. A screw (8) or a spiral groove is suitable as the guidance structure (6). Rotational motion of the shaft (11) being inserted causes the shape of the screw (8) or the spiral groove provided at the tip of the lip (4) to produce force in the lip (4), which force acts in the direction of causing the lip (4) to expand in diameter.</p> |
