Patent ID: 6769324
Filing Date: 2004-08-03
Classification: F16C,F16H,Y10T

Abstract:
A ball screw comprising:a screw shaft having a first helical ball rolling groove in an outer periphery thereof; a nut having a second helical ball rolling groove in an inner periphery thereof; a plurality of balls arranged in a helical raceway defined by the first and second helical ball rolling grooves, wherein at least one of the first and second helical ball rolling grooves has a surface with a surface roughness of 0.12 &mgr;m or less in average roughness (Ra) along a helical direction of the helical raceway; and a retainer rotatably supporting the balls between the screw shaft and the nut, wherein the retainer comprises a plurality of separators interposed between adjacent balls, each of the separators having concave surfaces on both sides thereof.