A Research on the Analysis and Design of CNC Servo System Considering the Machining Process

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Fundamental studies are conducted to analyze and synthesize the CNC servo system considering the machining process. To this end the simultaneous model which includes the CNC servo model as well as machining model (cutting force model) is established and used for constructing the adaptive process controller, which regulates the cutting force under the various contouring paths.1. The geometrical interference between endmill and workpieces is analyzed, and a quadratic polynomial model was proposed for cutting forces based on response surface methodology by two variables of the engagement angle of cutting tool and the maximum undeformed chip thickness. The model was examined on various cutting tests and found to be effective to predict the cutting forces.2. A servo model are constructed by considering 2 axis synchrous motion and feedrate override function. Then a simultaneous model is constructed and its prediction performances are checked.3. By using the simultaneous model, an adaptive control system is developed and simulated which regulates the cutting forces in end milling process. PI control is found to be effective by simulation and off line gain tuning is conducted. The control system designed by simulation is implemented and found to be effective on actual cutting tests in an intelligent machining center.