Abstract
Abstract
The present paper discusses a knowledge-based interactive CAPP system for symmetrical turned parts. In this system, which is modular in structure, special emphasis has been laid on geometric reasoning and cut planning—two aspects which have received little attention in the CAPP systems reported in published literature. The present paper deals mainly with the description of the cut planning module of UOR_PLAN. The task of cut planning in UOR_PLAN is divided into two subtasks—macro cut planning and micro cut planning. Macro cut planning deals with the identification of pockets of unwanted metal. As a first step a mesh of nodal points is generated by taking into account the geometry of the part profile and the shape of the blank. Next, by rule-based successive elimination of nodal points from the mesh, pockets of unwanted metal for a given operation sequence are identified. This process is repeated for all possible sequences. The distinguishing feature of this technique is that it identifies the machinable volumes automatically without the preparation of an incidence/precedence matrix. A further breakup of machinable volumes is dealt with in micro cut planning. In phase one of micro cut planning, each machinable volume is divided into a number of rough cuts of equal depth by leaving a suitable finishing allowance. Optimum machining parameters (depth of cut, feed rate, cutting speed and number of passes) are selected by applying the sequential unconstrained minimization technique (SUMT). The best of the cut plans is selected on the basis of minimum production time. Phase two of the micro cut planning deals with the removal of the finishing allowance and has been discussed in an earlier paper.