| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw having a long service life even if being used under high speed and high load conditions, and an injection molding machine using the same. SOLUTION: A ball screw 1 comprises a screw shaft 3 keeping a spiral screw groove 3a in an outer peripheral surface, a nut 5 having a spiral screw groove 5a formed in an inner peripheral surface and facing the screw groove 3a of the screw shaft 3, a plurality of balls 9 rollably loaded in a spiral ball rolling passage 7 formed of both the screw grooves 3a, 5a and a separator 11 arranged between balls 9 adjacent to each other. The screw shaft 3 and nut 5 are made of steel. The ball 9 is made of a ceramic material. The separator 11 is made of a resin. The screw shaft 3 and nut 5 are heat-treated, e.g., carburized. The amount of retained austenite contained in surface layer parts of the screw grooves 3a, 5a is between 15 vol.% and 40 vol.%. COPYRIGHT: (C)2010,JPO&INPIT
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