Patent ID: 7812493

Claim:
A spindle apparatus for a machine tool comprising: a housing; a spindle that is rotatably supported by the housing through a support-purpose bearing unit and is formed with a tool attaching portion at a distal end thereof; a driver that rotates the spindle; a tool attached to the tool attaching portion; a radial magnetic bearing that includes a plurality of electromagnets disposed around the tool attaching portion for suppressing vibration of the spindle; a plurality of radial displacement sensors provided around the tool attaching portion for detecting a displacement of the tool attaching portion in a radial direction; a support member fixed to the housing, the support member surrounding a portion of the spindle that is projected from the housing, and the support member fixing the radial magnetic bearing and the radial displacement sensors; and an electromagnet controller that controls the electromagnets of the radial magnetic bearing on the basis of outputs of the radial displacement sensors so as to support the tool attaching portion in a predetermined position.