An Analytical Model for Pitch Moment Stiffness of Bolted Connections and Its Application in Ballscrew Bearing Support Block Selection

Abstract

Bolted joints are commonly used structural connections as they provide a strong secure joint along with ease of assembly/disassembly. While analytical models for the axial stiffness of bolted joints are well developed, models for moment (angular) stiffness of bolted structures, such as ball screw bearing support blocks, are needed to help engineers rapidly design more efficient precision machines. This paper develops a parametric moment stiffness model for bolted connections which is verified via numerical and experimental methods. Application of the model is illustrated with a ball screw system design spreadsheet, available in Supplemental Material on the ASME Digital Collection, applied to two case studies (machine tool linear axis and high-speed 3D printer) to show how predicting the moment stiffness of ball screw support bearing blocks helps in expanding the available design space and enhance the design performance.