US Patent 7637856 Machine tool with spindle chuck replacing function

An object of the present invention is to provide a machine tool with a spindle chuck replacing function which has a simple configuration and enables a reduction in work replacement time. The machine tool with the spindle chuck replacing function includes a spindle 3, a spindle motor 4, a plurality of spindle chucks 5, 5, a spindle chuck replacing mechanism 10, a pre-rotation motor 7, a rotation speed sensing arrangement, and a replacement spindle motor speed control device. The replacement spindle motor speed control device controls the rotation speed of the spindle motor 4 according to a speed sensed by the rotation speed sensing arrangement so that when the spindle chuck replacing mechanism 10 passes the spindle chuck located at a spindle opposite position P1 to a chuck coupling portion 3a of the spindle 3, the rotation speed of the spindle 3 synchronizes with the rotation speed of the spindle chuck 5 located at the spindle opposite position P1.