| 摘要 |
Aball screw has : a screw shaft having a spiral ball rolling groove; a ball nut having a ball rolling groove corresponding to said ball rolling groove; and a large number of balls interposed between said ball rolling grooves so as to roll freely; wherein said ball rolling groove of at least one of said screw shaft and said ball nut is ground so that a maximum value component of a number of undulation peaks per lead in said ball rolling groove is out of a range of from 0.95nm to 1.05nm centered on an integral multiple nm of a number m of load balls per lead calculated by an expression: <DF><SQRT><SQUARE> pi dm</SQUARE> + L<2></SQRT> DIVIDED P </DF> in which P is a distance between centers of said adjacent load balls disposed at substantially equal intervals in said ball rolling groove, dm is a ball pitch circle diameter, and L is a lead. <IMAGE> |
