To provide a ball screw capable of suppressing scattering around a lubricant collected to a stroke end position of a screw shaft without being accompanied by increase in the number of components.
A ball screw 1 includes: a screw shaft 3 having a spiral thread groove 3a on an outer peripheral surface; a nut 5 having, on an inner surface, a spiral thread groove 5a facing the thread groove 3a of the screw shaft 3; a plurality of balls 9 freely rollably loaded inside a spiral ball rolling path 7 formed by both the thread grooves 3a and 5a; a ball circulation path 11 for circulating the balls 9 to return from the end point to the start point of the ball rolling path 7; and roughly annular contact seals 13, 13 which are attached to both ends in the axial direction of the nut 5 and are in slidable contact with the screw shaft 3. At a stroke end position of the nut 5 of the outer peripheral surface of the screw shaft 3, a recessed part 15 capable of storing a lubricant is provided. The recessed part 15 is turned to an annular groove continued in a circumferential direction of the screw shaft 3.
YAMAMOTO KAZUFUMI
Hide Tanaka Tetsu
Ichi Hirose
Toru Miyasaka