Research On Instantaneous Mechanical Model And Nonlinear Dynamic Characteristics For Milling Process System

In modern manufacturing system, end milling is widely used in machining processes. With the emergence of new manufacturing's concepts and technologies, for improving the quanlity of the product and production's efficiency, the study of milling modeling became a key issue. This dissertation is supported by NSF of China under research grant No.59705018/59889504. For the machining process of helical end milling, the emphases of the research are as follows:1. In order to predict the cutting forces and moments, an analytical cutting model in end milling with helical multi-flute cutters is developed in this paper. Milling moment is an important mechanical characteristic in the milling process. Through studying the relationship between elemental cutting moment and cutting force, a milling moment expression in the frequency domain is obtained. 2. In the end milling process, milling force/moment, machine tools and workpieces' characters are the elements which influence the generation of milled surfaces. Cutting forces/moment during machining produce the deformation of cutter, workpiece and machine tool. Through studying these elements, based on the relationship between milling forces/moments and instantaneous undeformed chip thickness, an analytical model for end milling surface geometric error with considering cutting forces/moments is built to predict the surface geometric error in the end milling conditions. Compared with the numerical model, the analytical model is more propitious to studying relationship between process parameters and surface geometric error, and provides a useful aid for the analysis of end milling process design and its optimization. It is also useful to identify the relationship between process parameters and workpieces' quality, product design, process planning and controll.3.In machining process, because of the negative influence to the surface of workpiece, cutters and the performance of machine tools, cutting vibration must be avoided. However, the machine tools-cutter-workpiece-fixture is a complicated nonlinear dynamic system. It is determined by the system's physical, geometry and milling process's characteristics. The dynamic capability of the milling process is influenced by a lot of nonlinear factors. Considering the machine tool's rigidity, time delay and uncontinuous cutting, etc, a nonlinear model to prodict the vibration is proposed in this paper. Based on this model, the chaos in dynamics system is investigated.4. Using the network technology, the integration of models and rapid construction of milling force model are dicussed.