Ultra-precision Grinding of the Wavy-tilt-dam Seal Rings Used in Reactor Coolant Pumps

Abstract

A three-axis ultra-precision grinding method using line contact kinematics for machining the wavy-tilt-dam seal rings used in reactor coolant pumps is proposed.It includes a workpiece axis,a swing axis,a linear axis,a wheel axis and a narrow cup wheel.The principle is that the grinding contact arc is an approximation to a curve on the wavy-tilted surface bounded by its inner and outer peripheries by selecting suitable wheel radius,wheel inclination angle and distance from intersection point of the workpiece axis and the swing axis to the dam surface center.The sweeping trajectory of the contact arc forms a wavy-tilted surface with high accuracy by numerically controlling the motion of the workpiece axis,the swing axis and the linear axis so that the two end point of the contact arc is on the inner and outer peripheries.The dam surface is generated when the wheel axis and the workpiced axis are parallel.The advantage is that the form of the wheel end face is constant and wheel truing and wheel form measurement are not needed,and hence the effect of wheel wear on the wavy-tilted surface form accuracy is neglectable.It is expected to be an efficient method to manufacture the wavy-tilt-dam seal rings used in reactor coolant pumps with high form accuracy and low surface roughness.