Automatic generation of dynamic clamping forces for machining fixtures

Automatic fixture configuration analysis is an essential issue in the conte xt of computer-integrated manufacturing. In this paper, a general methodolo gy for fixture configuration verification is presented, which is based on f orce closure and clamping equilibrium. The inclusion of a new clamping equi librium criterion ensures a robust clamping layout and hence reduces the po ssibility of workpiece displacement within a fixture. For clamping force an alysis, a new method for directly generating the minimal clamping intensity for planar fixtures is presented. Next, we develop a general friction meth odology of dynamic clamping analysis and planning for arbitrary-shaped work pieces based on nonlinear programming. The objective of the presented algor ithm is to determine a spectrum of minimum sustainable clamping forces for a machining process based on a proposed criterion of maximum friction. The set of variable clamping intensities is determined such that it is just eno ugh to counterbalance the dynamic cutting forces. This approach is more rea listic than other systems with static cutting conditions and frictionless c ontacts. The concept of maximum clamping forces is also proposed and a comp utation method is presented. The non-approximation representation of contac ting forces presented in this algorithm guarantees the existence of an opti mal clamping solution. Moreover, it makes the algorithm robust and reliable . Case studies are included to demonstrate the effectiveness and capabiliti es of the methodology.