| 摘要 |
PROBLEM TO BE SOLVED: To suppress the breakage of a fitting protuberance, and the reduction of a fixing force while maintaining a sure fitting-fixation by a method wherein an annular protuberance of one cylindrical body is formed of a top part which annularly continues, and a plurality of tilted walls which are arranged into a ring-shape, integrally connected to the top part, and with which the annular protuberances come into contact first when they get over the walls. SOLUTION: An external cap 1 has a top part 4a for the fixation of an internal cap 3, which annularly continues, and an inward protuberance wherein a plurality of tilted walls 4b which are integrally connected to the top part 4a and are circumferentially arranged, are provided, and the internal cap 3 has an annular outward protuberance 8. When the internal cap 3 is inserted in the external cap 1, firstly the outer protuberance 8 of the internal cap 3 comes into contact with the tilted walls 4b of the external cap 1. When the insertion is advanced further, the outer protuberance 8 starts getting over the tilted walls 4b, and at the same time, a force to deform outward is generated on the tilted walls 4b, and a force to deform inward is generated on the outward protuberance 8 of the internal cap 3. Then, the inward protuberance and the outward protuberance 8 reach the top part and get over each other, and an annular fitted contact relationship is completed. |
