Evaluation of Coupling System Characteristics Considering Contact Conditions Between Shaft and Borehole Surfaces

Abstract

Characteristics of the coupling system influence the characteristics of entire machines, such as ball screw feed drive systems. However, quantitatively evaluating the characteristics of coupling systems is difficult because coupling systems have frictional contact surfaces that exhibit nonlinear characteristics. Hence, effective evaluation and analysis methods have not been proposed, and factors that influence the characteristics have not been investigated. In this study, the influences of contact characteristics between shaft and borehole surfaces are investigated. The characteristics of several samples were evaluated by measuring frequency responses, and it was found that the stiffness and damping of the system varied with the fixing torque and geometry of the clamp hub. It is assumed that this phenomenon is attributable to the change of the contact surface pressure, which depends on the fixing torque and geometry of the clamp hubs. Concerning the stiffness, in this study, a simple model considering the real contact area to calculate the relationship between the contact surface pressure and contact stiffness was constructed. Results obtained by applying the model were compared with experimental results, and the proposed model was confirmed to be representative of the influences of the fixed torque and coupling clamp hub bore diameter.