Construction Of An Open Architecture Cnc System And A Series Of Study Of Its Key Technologies

Digital control technology is the basis to reach automatic, flexible and integrated manufacturing. It is classified as an urgent key industrial technology by all countries. Meanwhile, it also directly impacts on the level of equipment manufacturing's modernization. The development, promotion and application of digital control technology decide whether mechanical products are competitive at home and abroad by a huge margin. Appearance of the open architecture CNC system provides the very good opportunity for improving our NC lathe's technology. Development of the open architecture CNC system of proprietary intellectual property is an effective shortcut to close the gap between our country and other countries by making use of the rich resource of our intellectual capital. Against this backdrop, techniques of controller'realization and variant design for the open architecture CNC system are discussed in depth.Functional modules of the soft motion controller are developed based on object oriented programming techniques, dynamic link library techniques and interface standardization techniques. The soft CNC system platform is built with these modules. The machine tools are typical reactive systems, and their manufacturing operations register as complex dynamic behaviors. Dynamical behavioral modeling for motion controllers are all described using hierarchic Finite State Machine (FSM) model. FSM for each module is brought out during the development of the functional module. Controllers developed and controllers to be developed for the future needs are all organized based on the product family. Variant design methodology is proposed based on the family. Design of the controllers is a process of inheriting or expanding existing products and existing technology. Reuse and variant design of existing products make the controller design easier and provide an effective reuse of existing technology.Machines with 5 simultaneous motion axes are considered to manufacture the more complicated products in the manner of high speed and high accuracy at present. Curve interpolation function equipped by the well-known international brand control system makes a very good solution to the 5-axis linear interpolation function with many shortcomings and brings out a significant increase in performance for the machine tools. Unfortunately, the system with curve interpolation function is banned from exporting to China. It is significant to research the 5-axis curve interpolation and to realize it in an open architecture CNC system. A NURBS interpolation format for 5-axis machining is proposed based on analysis towards curve interpolation function of top quality machine tools. And an open motion controller with this kind of interpolation is developed. To realize the real-time control of 5-axis tool path, the motion controller firstly calculates orientation vectors and constructs the interpolation curve and the orientation curve through these vectors. A coordinated curve is achieved by establishing the mapping relationship between arc-length parameters of the position curve and angle parameters of the orientation curve. The problem of synchronized the linear axes and the rotary axes is well solved with these three spline curves. Superiority of this method is proved by making a comparison with the interpolation method taking parameters of the position curve and the orientation curve the same. Experiments show the feasibility of the interpolation function.The traditional 5-axis interpolation function is closely related to structure of machine tools. A motion controller exclusively belongs to a certain CNC machine tool. As far as an idiographic NC file is concerned, it will be trashy when there is a change of machine tool's structure or the part's position. To solve this problem, a curve interpolation method is proposed towards discrete cutter location, with CAD/CAM function being integrated as well. The related curve interpolation function is developed. In order to reduce the effect of errors in calculating orientation vectors, a cutter vector is used for representing tool orientation. A position curve, an orientation curve and a coordinated curve are generated by the controller according to the input discrete tool path. The controller is independent to the structure of machine tools. As a result, programming of NC files becomes easier. Also, adaptability of the controller is enhanced. Simulation analysis and experiments show both the validity of the interpolation algorithm and feasibility of the interpolation function.The bodies moving in fluid are designed with a fair profile to reduce movement resistance. To meet special requirements in machining these parts, a NC program preprocessor is developed. This preprocessor firstly judges the fairness of curve, then revises the bad points in the curve, and finally outputs the NC program. For curves of big deflection, energy methods are adopted and selected-point method is used for curves of small deflection. This preprocessor has a practical value for machining parts with special requirements of the fair profile.