Rotary ball screw spline assembly

Abstract

A rotary ball screw spline assembly includes a shaft, a ball nut and a ball spline. The ball nut is arranged on the shaft and has a plurality of first balls rolling on a thread rolling groove. There is a first distance between the center of each first ball located in the thread rolling groove and an axis of the shaft. The ball spline is arranged on the shaft, and the ball spline comprises a spline outer cylinder and a plurality of second balls arranged on the spline outer cylinder and rolling on a linear rolling groove. There is a second distance between the center of each second ball located in the linear rolling groove and the axis of the shaft, and the second distance is greater than the first distance. When the outer diameter of the ball spline meets a specific formula, the optimal outer diameter of the ball spline can be obtained to effectively reduce the volume of the ball spline and achieve low inertia operation of the rotary ball shaft spline assembly during operation.

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