The authors describe a procedure for the automatic design of a preform based on circumscription algorithms. The procedure is defined in general terms and applied to preforms realized by axisymmetric deep-drawing processes. The automatic design procedure is supervised by a 'generate, test, and rectify' tactic. The 'generate' stage hypothesizes a deep-drawn preform that either contains the finished workpiece or is 'close' to doing so. If the workpiece is not fully contained by the initial preform, the latter is 'rectified'. Rectification applies small changes to the radii of bending and to the wall thickness of the hypothesized preform cup. Either rectification continues recursively or a new hypothesis is generate. The cup is defined by its medial and a nominal uniform wall thickness. The design is accepted when a circumscribing cup is produced. The supervisory search mechanism is a combination of A*, hill-climbing, and depth-first.>

A real-time compensation scheme for geometric and thermally-induced errors of a computerized numerical control (CNC) turning center is described. The compensation system predicts these errors using a combination of data taken from various sensors on the machine tool and previously established relationships (transfer functions). The system translates these errors into servo counts and injects them into the control loops of the machine tool controller in real-time. A single-board microcomputer interfaced to the machine tool controller and the sensors is the workhorse of the system. The system control software written in PLM, a high level programming language, is modular, flexible, and easily maintainable. To evaluate the capabilities of the compensation system, a series of cutting tests have been performed, and the results are presented. Along with the elimination of machine warmup periods of 8 to 12 hours, significant geometric accuracy improvements in straightness and squareness have been achieved. An additional accomplishment is a dimensional accuracy improvement of up to 20 times over that of uncompensated workpieces.