Explicit precision friction torque model of ball screws in high speed operations

Precision friction torques of double-nut 2-point contact ball screws for the material, geometry, assembly and operating conditions are modeled explicitly. The nonuniform contact load, spin friction, ball motion, contact angle variation by the gyroscopic moment and centrifugal force, and temperature effects have been incorporated into the friction model. Contrary to maker's model with 34.69% accuracy, 96.78% prediction accuracy has been verified on the developed friction torque tester. Comparing with shorter lead ball screws with high rpms, longer lead screws operating with low rpms generate lower friction torques and are more efficient in high speed motions. In addition, the TC assembly and load condition is more efficient and lower friction than the TT case.