METHOD AND MACHINE TOOL FOR MACHINING VALVE SEAT SURFACE

摘要

A method of machining the surface of a valve seat (3) which must be precisely centered with respect to the hole of a valve guide (2) and a machine tool for this method. A method of machining the surface of a valve seat comprising the steps of: picking up the guide hole of a valve guide (2) with the tip of a pilot member (4), which is freely tiltably advanceable so that it can maintain the desired concentricity with the guide hole and finish the surface of the valve seat in an accurate, true circle; in this way bendably feeding the pilot member forward following the guide hole; fixedly holding the attitude of the pilot member when it has been advanced to the desired position; and feeding a cutter member (5a) coaxial with the pilot member forward while rotating it to mechanically machine the surface of the valve seat. A machine tool capable of carrying out this method comprises a longitudinally movable spindle (8), a pilot member (4) bendable at (7) with respect to the spindle, a bearing member (15) for the pilot member capable of being centered with respect to the pilot member, means (17) for holding the bearing member coaxially with the pilot member, and a cutter member (5a) arranged so as to be rotatable coaxially with the pilot member and longitudinally movable integral therewith.