| 摘要 |
PROBLEM TO BE SOLVED: To solve a conventional problem that machining stages increase as a result of centering performed every time a crankshaft half 14 is moved in machining a pin hole 13 by means of an internal cylindrical grinding machine and a spot facing 58 by means of another milling machine to finish the crankshaft half 14 having the pin hole 13. SOLUTION: Fig. (a) illustrates machining of the pin hole. The crankshaft half 14 is centered on a rotary main spindle 29 and clamped by clamp means 31, 32, and the pin hole 13 is machined by an outer periphery 26a of a tool 26 with the crankshaft half 14 being rotated. Fig. (b) illustrates machining of the spot facing. With the crankshaft half 14 staying as is, the tool 26 is retreated, and the spot facing 58 around the pin hole 13 is formed by a front side 26b of the retreated tool 26. Since the machining of the pin hole and the spot facing of the crankshaft half can be carried out by one setting without removing the crankshaft half from the machining device, the machining stages can be substantially reduced.
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