Numerical study on the effectiveness of the optimization of the load distribution in ball screw actuators

Load distribution in ball screws is characterized by non-uniformity, leading to imbalances in the contact load of the balls along the nut. This non-uniformity negatively impacts the stiffness, accuracy and service life of the ball screw. This work proposes a solution to reduce the ball screw load distribution non-uniformity through an optimization model and two implementation methods: the variable pitch method and the ball offset method. Both methods involve applying an initial preload in certain areas of the nut to compensate for load imbalance. A case study tests both methods and evaluates the implications of implementing the optimization model. Results confirm the model's ability to reduce the load distribution non-uniformity, with a ratio improvements up to 61%. Additionally, this optimization enhances stiffness by up to 78% and extends service life by up to 17 times. The study also identifies the model's limits and possible adverse effects, concluding that the specific case conditions must be considered in the optimization process.