| 摘要 |
PROBLEM TO BE SOLVED: To provide a dustproof cover corresponding to the length of a tool at low cost by forming a cylindrical dustproof cover covering the surrounding of a drilling tool out of a flexible material and connecting bellows cylindrical bodies each other having ruggedness of substantially the same pitch each other in the axial direction by overlapping projecting and recessing parts of end parts each other. SOLUTION: A dustproof device is constituted of a base part constituted of an inside cylinder, an outside cylinder, a bearing and a base end wall and a dustproof cover 60. The dustproof cover 60 is integrally formed of materials easy to be elastically deformed and has a size to cover the whole of a body from the outside. Bellows cylinders 62, 63 extendible and contractible in the axial direction are connected by being overlapped each other and are made to have a prescribed length. At a tip of the bellows cylindrical body 62 on the tip side, a doughnut plate-shaped tip wall 64 is formed. At a rear end of the bellows cylindrical body 63 on the rear side, a cylindrical mounting part 66 projecting in the axial direction is formed. As a result, the dustproof cover corresponding to the length of a tool can be obtained at low cost.
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