Ball screw mechanism has holding piece with outside diameter prevented from contacting inner wall of thread groove circuit and return circuit when load ball passes through thread groove circuit and return

摘要

A holding piece (10) has two concave surfaces (11) which meet between adjacent load balls. The load balls are respectively provided to the holding piece. The retaining piece has an outside diameter with 0.5 increment or more with the outside diameter of the load ball (5) to prevent from contacting the inner walls of a thread groove circuit and a return circuit (12) when the load ball passes through both circuits.