JP2004069013A5 - - Google Patents

Claims (7)

A screw shaft having a first screw groove on the outer peripheral surface, a nut having a second screw groove on the inner peripheral surface facing the first screw groove formed on the screw shaft, and the first and second In a ball screw comprising a plurality of balls disposed so as to be freely rollable between screw grooves, the screw shaft and the nut are made of a titanium alloy, and the ball is made of ceramics.
The ball screw is characterized in that the nut comprises a first nut and a second nut inserted with a preload adjusting spacer therebetween.   The ball screw according to claim 1, wherein the spacer is made of a titanium alloy.   The spacer is composed of two or more different materials stacked in the axial direction, and the linear expansion coefficient in the axial direction of the entire spacer is equal to that of the titanium alloy. The ball screw according to claim 1, wherein the thickness in the direction is adjusted.   The ball screw according to claim 3, wherein the material constituting the spacer is a titanium alloy and an aluminum alloy.   The ball screw according to claim 3, wherein the material constituting the spacer is a titanium alloy and ceramics.   The ball screw according to claim 3, wherein the material constituting the spacer is ceramic and an aluminum alloy. The first nut and the second nut are integrally fixed by a key material, and the key material is made of a titanium alloy. Ball screw as described in.