Tool spindle and machine tool including same

A machine tool, comprising:

• a column installed in a first side of a bed to be movable in an X axis direction and a Y axis direction;
• a spindle housing installed on the column to be movable in a Z axis direction;
• a B axis indexing device installed on the spindle housing;
• a tool spindle installed on the B axis indexing device to be rotatable about a B axis, wherein a tool is mounted to a first end of the tool spindle;
• and
• a vibration damping device mounted to a second end of the tool spindle to damp cutting vibration generated at the first end of the tool spindle, wherein the first end of the tool spindle and the second end of the spindle are opposite to each other,
• wherein the vibration damping device comprises:
• at least one rigid member coupled to the second end of the tool spindle;
• a tuned mass member supported by the at least one rigid member;
• and
• an additional mass member received within a receiving recess of the tuned mass member to be movable therein,
• wherein
• the at least one rigid member comprises a plurality of rigid members, wherein each of the rigid members comprises a respective stiffness rod that extends away from the second end of the tool spindle and that is outside of the receiving recess,
• the tuned mass member is supported by the plurality of stiffness rods to be spaced apart from the second end of the tool spindle by a predetermined distance,
• the receiving recess extends from an outer surface of the tuned mass member into the tuned mass member by a predetermined depth, and
• a sealing cap is fastened to the outer surface of the tuned mass member to cover the receiving recess.