| 摘要 |
PROBLEM TO BE SOLVED: To efficiently perform a stripping operation. SOLUTION: A bottomed, cylindrical closure member 18 for closing an opening 19 in a bottomed, cylindrical bush main body 17 provided with a slip off preventive means on its outer periphery is threaded into the bush main body 17 and an internal thread part 30 comprising multiple threads is provided on the inner periphery of the closure member 18. A bush locking part 6 formed of a material harder than the closure member 18 is projected from the inner surface of a form and an external thread part 5 having a smaller number of threads than the internal thread part 30 is provided on the outer periphery of the bush locking part 6. By threadably engaging the internal thread part 30 with the external thread part 5, the number of meshing parts between the internal thread part 30 and the external thread part 5 can be made smaller than that of a screw with the same number of threads, and the internal thread part 30 is rendered more susceptible to deformation through the operation of pulling the bush locking part 6, so that during stripping the bush locking part 6, together with a form, is forcibly and smoothly removed from the closure member integrally threaded in the bush main body 17.
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