Valve seat with trapped O-ring

摘要

A valve seat (28) having a generally saddle-shaped, eccentric surface (52); a groove (50) of constant depth and width formed in the eccentric surface, having sidewalls (70) perpendicular to the eccentric surface and a base (72) parallel to the eccentric surface; and a flexible O-ring (54) retained by friction within the groove. The groove sidewalls and base have a surface finish in the range of about 32 to 125, which provides sufficient smoothness to retain the O-ring in the required non-planar shape. The valve seat groove (50) can be produced according to the disclosed method, which is preferably implemented in a numerically controlled four-axis horizontal milling tool system. The valve seat part (100) is mounted in a fixture (102) on a rotary table (104) such that the part axis (56) is aligned with the longitudinal axis (Z) of the tool (106). Once the initial penetration position and depth of the tool (106) is established on the eccentric surface (52a) of the part (100), the only required machine movements are table rotation (104) and tool vertical axis movement (Y).