The Research On Micro-movement Characteristics Of Ultra-precision Machine Tool Feeding System & QFT Controller

Ultra-precision machining is an advanced manufacturing technology, which is based on applications in the mechanical development of comprehensive new achievements, and other new technologies. It has increased the Machining accuracy substantially, and is in the challenges of nano-scale level. The precision machine tool is the fundamental equipment to fulfill advanced techniques of manufactory. It plays a decisive role in ultra-precision machining technology research and development process.The servo control system of the precision machine tool is the key factor because its performance decides the machining accuracy, surface quality of the work-piece and productivity of the machine tool directly. The motion characteristics of feeding mechanism are the foundation of its control strategy research. And decide the motion accuracy of feeding mechanism. The main contents are as follows:1. For the feed mechanism drove by ball screw, analyzed the force of the ball, and influences rooted in friction, contact stiffness, backlash, and so on. Put forward some relevant measures. Educe the characteristics of the micro-movement of the feed mechanism.2. Establish mathematical model making use of electrical and mechanical methods of separation. Abstracted the machine feeding system to two modules, electric drive modules and mechanical transmission modules in series, and set up the transfer function of each module firstly. Then, merged them together, establishing the overall system mathematical model.3. Analyzed the control mechanism of the conventional ultra-precision machine tool controller. Through the analysis of the object uncertainty and the input signal to the tracking error, determined that the initial location controller of PI could be used to the ultra-precision machine.4. According to the existence of uncertainties, made use of quantitative feedback theory (QFT) design the method of the servo system controller. System robustness is the basic requirements of the ultra-precision machine tool servo control system, the controller based on this theory ensured a strong robustness. Result shows that the controller can achieve the requirements of the ultra-precision machining in the case of uncertainties existed.