Patent ID: 7987567

Claim:
A machine tool comprising: a double column frame comprising a pair of horizontally spaced columns vertically mounted on a bed and a beam extending horizontally along a Z-axis between upper portions of the columns, said double column frame being horizontally elongate and disposed on said bed; a movable unit horizontally movable along said double column frame, said movable unit having a tool rest for holding a tool for machining a workpiece; a pair of guide rails mounted on said bed and spaced from each other in a direction perpendicular to said Z-axis, said guide rails extending horizontally parallel to each other, said movable unit being horizontally movably supported on said guide rails; and an upper ball screw and a lower ball screw for moving said movable unit horizontally said upper ball screw and said lower ball screw being mounted respectively on upper and lower portions of said double column frame and extending horizontally and supported by said double column frame; wherein forces are prevented from being transferred between said beam and said movable unit.