Splined ball screw assembly having a nested structure

摘要

A splined ball screw assembly having a nested structure is provided. A hollow shaft extends into an outer sleeve and a center shaft extends into the hollow portion of the hollow shaft. A ball screw structure is provided at either side of the outer and inner peripheral surfaces of the hollow shaft and a ball spline structure is provided on the other side. The outer sleeve is rotatably mounted on a housing and the center shaft is also rotatably mounted on the housing. By controlling the amount and direction of rotation of both of the outer sleeve and the center shaft, the hollow shaft may be moved longitudinally in a desired direction and/or set in rotation. The present assembly is compact in size and particularly suitable for use in a robot arm.