US Patent 7266870 Mandrel device for machine tool

A mandrel device includes a spindle for rotatably attaching to a machine tool, a rotating device for selectively rotating the spindle, and a driving device for selectively driving the spindle in different speed or different torque when the rotating device do not rotate the spindle. The rotating device includes a motor coupled to or engaged with the spindle for rotating the spindle. A housing may be attached to the machine tool for rotatably supporting the spindle, and the motor may be disposed in the housing and engaged with the spindle. The driving device includes a gear attached to the spindle, a worm movable toward or away from the gear, and a motor coupled to the worm for rotating the spindle with the gear and the worm.