| 摘要 |
PROBLEM TO BE SOLVED: To precisely discriminate the type of a dry 11 diameter by providing one-several recessed holes or recessed grooves in one cylindrical end or both ends of the fixing ring 1 or a cylindrical outer circumferential face and discrimi nating the type of the dry 11 diameter. SOLUTION: A drill is used for one cylindrical face or both end faces of a fixing ring 1 for a drill so as to form two recessed holes 2 of the depth approximately 0.3 mm. The insides of the holes 2 are colored into black, white, yellow, blue, or red with imperishable ink or coating so as to be easily observed. The discrimination types of fixing rings 1 are, for example, 12 color types of the colored rings, 6 types of recessed holes 2 and recessed grooves, and 4 color types in the insides of the recessed holes 2, and so in total, 12×6×4=288 types can be discriminated.
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