| 摘要 |
PROBLEM TO BE SOLVED: To easily, smoothly and accurately effect the next clamping action of a tool rest while allowing for not only the machining error and secular change of a coupling but also the influences of machining. SOLUTION: This invention is applied to a lathe wherein a tool rest 5 is swiveled by a servomotor 16 and clamped by a coupling 17, with motor torque set at zero after clamping is finished. Just before the next tool on the tool rest 5 is indexed after machining is complete, the differences between the angles (current values) of the current tool retaining surfaces T1, T2,... and the angles (reference values) of the current tool retaining surfaces T1, T2,... are computed and stored in a computing result storage part 40. At the same time, for a new indexing command, the reference values read from an indexing command reference value setting part 38 are corrected using the differences stored as to the tool retaining surfaces T1, T2..., thereby determining actually indexed positions.
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