| 摘要 |
PURPOSE:To make a deep drilling part of a holder part machinable so accurately and rotable at high speed in a stable manner, by machining each of cylindrical members splitting up the bobbin holder separately and combining them into an integral construction. CONSTITUTION:A bobbin holder part 2 is split into two parts, a front cylindrical member 3 and a rear cylindrical member 4, and this front cylindrical member 3 is unitized with the same member as a bobbin holder shaft 2. And, overall length of the rear cylindrical member 4 forming a rear part of the bobbin holder part 2 is shorter as much as a range from 1/2 to 1/3 or so as compared with the bobbin holder part formed with one member, so that like such one of 600mm or so in overall length of the bobbin holder hereto fore in use, it can be supported without eccentricity at the time of machining and, what is more, even at the time of machining both inner and outer diameters of the cylindrical part, it can be done accurately without entailing any dislocation in the axial center. On the other hand, the front cylindrical member 3 forming a front part of the bobbin holder part 1 is of the same member extended on the same axis as the bobbin holder shaft 5, and since drilling length is also short, it is accurately machinable. Therefore, if the bobbin holder is rotated at high speed, its vibration is little.
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