Abstract: A spindle condition detection device for a machine tool includes: bearing load detecting means for detecting a load on a bearing that rotatably supports a spindle of a machine tool; and present usage ratio calculating means for calculating, based on the load detected by the bearing load detecting means, a present usage ratio that is a ratio of usage of the bearing with respect to a prescribed operating life of the bearing, which is achieved over a period until a present moment.

Abstract: A spindle condition detection device for a machine tool includes: bearing load detecting means for detecting a load on a bearing that rotatably supports a spindle of a machine tool; and present usage ratio calculating means for calculating, based on the load detected by the bearing load detecting means, a present usage ratio that is a ratio of usage of the bearing with respect to a prescribed operating life of the bearing, which is achieved over a period until a present moment.

Abstract: A touchdown bearing device includes an outer ring fixed to a housing, an inner ring radially opposed to the outer ring, an intermediate ring radially interposed between the outer ring and the inner ring, a first ball interposed between the outer ring and the intermediate ring, and a second ball interposed between the intermediate ring and the inner ring. The touchdown bearing device is configured so that when a magnetic bearing normally operate, a rotary shaft and the inner ring are brought into a noncontact state, and that meanwhile, when the magnetic bearing does not normally operate, the rotary shaft is supported by the inner ring so as to support the rotary shaft against the housing.