Apparatus for cooling and load-compensating ram spindle and machine tool including same

A machine tool comprising an apparatus for cooling a ram spindle and compensating for a load, the machine tool comprising:

• a bed;
• a pair of columns installed at two opposite sides of the bed and extending in a height direction;
• a cross rail installed to be transferred along the pair of columns;
• a saddle installed to be transferred along the cross rail;
• a ram spindle installed to be transferred along the saddle;
• and
• an apparatus for cooling the ram spindle and compensating for a load configured to cool the ram spindle and compensate for a load when the ram spindle is thermally expanded,
• wherein the apparatus for cooling a ram spindle and compensating for a load comprises:
• a transfer unit having a driving unit and configured to transfer the ram spindle relative to the saddle by means of a box guideway;
• a cooling unit configured to cool the ram spindle;
• and
• a load compensation unit including a plurality of gibs provided inside the saddle, disposed between the saddle and the ram spindle, except for a reference surface with which the ram spindle is in close contact, and installed to correspond to the reference surface in a horizontal direction or a vertical direction, the load compensation unit being configured to automatically compensate for a load applied from the ram spindle to the saddle,
• wherein the cooling unit cools the ram spindle when the ram spindle is thermally deformed, and
• wherein when a load applied to the gib is changed by the thermal deformation of the ram spindle, the load is automatically compensated so that surface pressure applied to the gib is constantly maintained,
• wherein the reference surface is provided as a plurality of reference surfaces with which an inner part of the saddle adjacent to the driving unit and a part adjacent to an outer edge of the ram spindle are in close contact, and
• wherein the gibs are provided as four gibs installed between upper and lower sides of the inner part of the saddle, and an individual gib faces a respective reference surface of the plurality of reference surfaces, and the part adjacent to the outer edge of the ram spindle based on a diagonal line passing through edges of the ram spindle, which are not adjacent to one another, based on the plurality of reference surfaces.