An improved computation model for critical bending force of three-jaw chucks

Because of its automatic centering capability, and its high flexibility with respect to different clamping diameters, the three-jaw chuck is the preferred clamping device for turning operations. However, because of insufficient modelling methods, the existing approaches for determining the required clamping force of jaw-chucks lead to unreliable and inconsistent computation results. This is especially true for the crucial computation of critical bending force. An improved analytic computation model for determining the critical bending force of three-jaw chucks is introduced in this article, and verified through experimental investigations. Finite element analysis-based knowledge about both the pressure distribution on clamping surfaces, and workpiece stiffness behaviour, ensures a safe and exact computation of the critical bending force and the critical bending moment. This exact computation makes it possible to utilize the potential of jaw-chucks at higher rotational speeds and guarantees safe workpiece clamping. (C) 2008 Elsevier B.V. All rights reserved.