摘要 |
A master spindle is provided to insert a spindle shaft into a bushing cap to allow the spindle shaft to relatively rotate to the bushing cap by a bearing. A master spindle includes needle bearings(12,14) and thrust bearings(16,18) mounted in a bushing cap(10), a spindle holder(24) to mount a collet(22) to fix a tapping tool(20), and a spindle shaft(26) integrally formed with the spindle holder. The spindle shaft is inserted into the bushing cap. Thus, a rear end of the spindle holder(24) closely contacts a first thrust bearing mounted to the bushing cap, and a supporting ring(28) fitted around the spindle shaft closely contacts a second thrust bearing of the bushing cap. Therefore, the bushing cap is mounted on the spindle shaft and the spindle shaft relatively rotates due to needle bearings with respect to the bushing cap. The bushing cap has a flange(13) with a coupling hole(11) formed at the leading end, and the first and second thrust bearings are mounted around the needle bearings. The master spindle further includes a fixing jig to fix the bushing cap.
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