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

对考虑加工过程的数控伺服系统进行了分析和综合的基础研究。为此，建立了包括数控伺服模型和加工模型（切削力模型）在内的同步模型，并将其用于构建自适应过程控制器，以调节各种轮廓路径下的切削力。分析了立铣刀与工件的几何干涉，提出了基于响应面法的以刀具啮合角和最大未变形切屑厚度为变量的切削力二次多项式模型。通过各种切削试验验证了该模型对切削力的预测是有效的。考虑两轴同步运动和进给速度覆盖函数，建立了伺服模型。然后构建了一个同步模型，并对其预测性能进行了检验。利用同步模型，开发并仿真了立铣削过程中切削力调节的自适应控制系统。仿真结果表明PI控制是有效的，并进行了离线增益整定。通过仿真设计的控制系统在某智能加工中心的实际切削试验中得到了有效的应用。

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.