Patent ID: 7506426

Claim:
A machine tool for machining a workpiece by moving a cutting tool relative to the workpiece while rotating the cutting tool, said machine tool comprising: a table configured to be movable along a specific feed direction in a horizontal plane with the workpiece placed on a top surface of said table; a main spindle unit including a main spindle for rotating said cutting tool attached thereto with said main spindle positioned perpendicular to the top surface of said table, said main spindle unit being configured to be movable along a moving direction perpendicular to the feed direction of said table in a horizontal plane above said table; a cross rail supporting said main spindle unit in such a manner that said main spindle unit can move along said moving direction perpendicular to the feed direction of said table in the horizontal plane; a plurality of columns for vertically guiding said cross rail, said columns being erected at positions on opposite sides of said table along the moving direction of said main spindle unit and said columns being located on front and rear sides of the center of gravity of said main spindle unit along the feed direction of said table; and a supportive transfer system including a member coming into direct contact with said cross rail to support said cross rail and operable to give a drive power to said cross rail to move said cross rail vertically; wherein said cross rail has a pair of supporting portions for supporting front and rear portions of said main spindle unit located frontward and rearward along the feed direction of said table with respect to the center of gravity of said main spindle unit, respectively, and a plurality of through holes through which said plurality of columns are passed vertically.