| 摘要 |
PROBLEM TO BE SOLVED: To prevent a deterioration of roundness caused by excessively grinding, a part close to a large-bore transverse hole for venting having high grinding surface pressure as compared with the other parts, in a grind finishing process of a crank shaft. SOLUTION: This compressor has an electric drive element 2, a compressing element 3 driven by the driving force of the electric drive element 2, and a crankshaft 5 rotatably inserted in bearings 7, 8 to transmit the driving force of the electric drive element 2 to the compressing element 3. The crank shaft 5 is provided with a longitudinal hole 9 opening at one end and longitudinally bored, a relief area 5d having a diameter differing from the diameter at a contacting point with the bearings, and a transverse hole 11 for venting bored to communicate from the longitudinal hole 9 to the relief area 5d in the relief area 5d. The crankshaft 5 is inserted in the bearings 7, 8 so as to make the relief area 5d project out from the bearings.
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