| 摘要 |
A spindle unit (1) comprises a plurality of rolling bearings (5a, 5b) which support a spindle (2), housings (3, 4) provided around the rolling bearings (5a, 5b) for supporting same, and a sliding sleeve (11) for pre-load change which freely slides in an axial direction of the housing (4) between at least one (5b) of the rolling bearings (5a, 5b) and the housing (4) and is provided to press an outer ring (6b) of the rolling bearing (5b), wherein a pre-load of the rolling bearings (5a, 5b) is changed in accordance with a rotational speed of the spindle (2). And the spindle unit (1) is characterized in that a static pressure operation portion (22) in the shape of an annular groove is formed between the housing (4) and the sliding sleeve (11), and a fluid pressure providing means (24) is provided to supply fluid pressure to the static pressure operation portion (22), whereby the sliding sleeve (11) slides at least when the pre-load is changed with keeping such a condition that fluid pressure has operated on the static pressure operation portion (22). <IMAGE> |
