Patent ID: 11953080
Assignee: APPLE INC.
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F  B | IPC B  F

Claim 11:
12. A ball screw spline actuator, comprising:
a shaft having a longitudinal axis, the shaft defining a helical groove and a spline groove each having an arcuate cross-section and extending along the shaft, the spline groove intersecting the helical groove at a plurality of intersections forming four ridges each having a surface finished edge extending into each intersection configured to reduce a stress concentration in the ridges when placed under a cyclical load;
a ball nut engaged with the helical groove configured to apply a first torque to the shaft about the longitudinal axis; and
a ball spline engaged with the spline groove configured to apply a second torque to the shaft about the longitudinal axis configured to linearly translate the shaft along the longitudinal axis relative to the ball nut and the ball spline and preventing rotation of the shaft about the longitudinal axis,
wherein each of the surface finished edges comprises curved sidewalls formed at a first time by the helical groove and the spline groove adjacently positioned to the helical groove, the curved sidewalls converging to define an edge, the surface finished edge formed at the edge at a second time subsequent to the first time, and
wherein the surface finished edge comprises a radius between the curved sidewalls.