Apparatus and method for machining valve seats in an engine cylinder head

Abstract

The valve seat and guide machine comprises a base structure which supports a pantograph having a major arm and minor arm which moves slidably with respect to the major arm. A spherical head is supported by a number of sphere seats attached to the pantograph arm so that the spherical head can pivot around its centerpoint. A stepper motor provides small z-axis translation of the spindle which is contained in the spherical head and has a cutting bit and a pilot which extend from the bottom of the spherical head. A drive motor rotates a transmission linkage which is coupled to the spindle which rotates the cutting bit to cut the valve seat. Small x,y displacements are enabled by moving the entire spherical housing and its supporting sphere seats with respect to the support frame. The pantograph provides large z-axis displacement to remove the spindle from the cutting position and to provide clearance for movement to another machine site. A system controller receives feedback from system monitors to control the spindle rotation and translation. Such information can be stored on a removable memory card for repeatable machining. The cylinder head is held in place by a pair of supports which allow the rotation of the cylinder head for easy positioning of the valve guides in the plane of the spherical head and spindle. These supports are moveable from side-to-side to allow the cylinder head to be moved so that successive valve seats may be machined.