Patent ID: 7240411

Claim:
A machine tool comprising a spindle supporting mechanism by which a spindle disposed on a bed is supported to be movable in X-axis, Y-axis, and Z-axis directions, wherein said spindle supporting mechanism comprises: a cross slide supported via a saddle by a column disposed on the bed to be movable in the Z-axis (left/right) and X-axis (up/down) directions; and a cylindrical ram supported by said cross slide to be movable in the Y-axis direction and supporting the spindle, and wherein said ram is slidably inserted in a ram guide hole formed in said cross slide and has a supported surface formed on a lower side of an outer circumferential surface thereof, said cross slide has a supporting surface which is formed on a lower side of an inner circumferential surface of the ram guide hole and by which the supported surface is supported to be slidable in the Y axis direction, and the supporting surface and the supported surface automatically align a Z-axis direction position of said ram, wherein said ram has a pressed surface formed on an upper side of the outer circumferential surface, and the ram guide hole of said cross slide has a pressing surface formed on an upper side of the inner circumferential surface and slidably pressing the pressed surface, and wherein the outer circumferential surface of said ram is in a polygonal shape, in which two lower sides constitute the supported surface in a V-shape and two upper sides among the other sides constitute the pressed surface in a V-shape, and the supporting surface and the pressing surface in a V-shape are formed on the lower side and the upper side of the inner circumferential surface of the ram guide hole of said cross slide respectively.