Analysis of reactions and minimum clamping force for machining fixtures with large contact areas

This pal,er presents a model for analysing the reaction forces and moments for machining fixtures with large contact areas, e.g. a mechanical vice. Su ch fixtures transmit torsional loads in addition to normal and tangential l oads and thus differ from fixtures using point or line contacts. The model is developed using a contact mechanics approach where the workpiece is assu med to be elastic in the contact region and the fixture element is treated as rigid. Closed-form contact compliance solutions for normal, tangential, and torsional loads are used to derive the elastic deformation model for ea ch contact. A minimum energy principle is used to solve the multiple contac t problem yielding unique predictions of the fixture-workpiece contact forc es and moments due to clamping and machining forces. This model is then use d to determine the minimum clamping force necessary to keep the workpiece i n static equilibrium during machining. Aln example is given to demonstrate its effectiveness in analysing the clamping performance of a mechanical vic e during machining.