Patent ID: 6173494
Filing Date: 2001-01-16
Classification: B24B,F02M,Y10T

Abstract:
A method of making a valve seat for a ball valve comprising the steps of:(a) forming a body as a workpiece with a conical cavity centered on an axis and having a machined conical surface with shape deviations from the circular in transverse cross section;(b) clamping said body in a workpiece holder and rotating said workpiece in one sense about said axis; and(c) securing a cylindrical grinding tool capable of finish-grinding of said workpiece in a tool holder which permits radial movement of said tool, rotating said tool about said axis in an opposite sense and urging an end of said tool against said conical surface while orienting said tool at an angle of attack .alpha. of 1 to 10.degree. to said axis, thereby forming said conical surface with an annular finish-ground seating surface of circular-arc-segmental shape in axial section engageable by the ball valve and having a radius of curvature greater than a radius of said ball valve, said seating surface constituting a trough in said conical surface of dimensions sufficient to eliminate said shape deviations along said seating surface.