Composite motion guide device

Claim 1

A composite motion guide device comprising: a single shaft means provided with helical ball screw grooves formed in an outer peripheral surface thereof and ball spline grooves formed in the outer peripheral surface thereof so as to extend in an axial direction of the shaft across the ball screw grooves, the respective ball screw grooves and ball spline grooves having groove depths equal to each other; a ball screw nut mounted on said shaft means and provided with ball rolling grooves being engageable with said ball screw grooves through loaded balls; a hollow ball spline outer cylinder mounted on said shaft means and provided with ball rolling grooves being engageable with said ball spline grooves through loaded balls; a retainer means disposed in a bore of said spline outer cylinder, said retainer means being of a thin walled cylindrical form and having slits disposed facing the ball rolling grooves, the slits having opposed curved surfaces for receiving and guiding loaded balls in the longitudinal direction of the shaft, the opposed surfaces being defined by a diameter substantially equal to a diameter of the loaded balls; a number of balls rolling in said ball screw grooves and ball spline grooves; means for independently driving said nut and said spline outer cylinder from each other; means for pre-loading the balls interposed between said nut and said shaft means in an axial direction thereof; means for pre-loading balls incorporated in said support bearing in support of said nut; and means for pre-loading balls interposed between said spline outer cylinder and said shaft means in a substantially rotating direction thereof.