Research On The Methods And Technologies For High Performance Peripheral Machining Of Complex Surface

With the development of aerospace, national defense, carrier and energy fields, some key workpieces with high accuracy need to improve machining efficiency and yield. These workpieces are machined using five-axis machining center. However, most classical tool path planning and feed rate scheduling methods only consider the machining process from a purely geometric perspective, and rarely take into account kinematic and mechanical properties of machine systems. Actually, the machining process is not only a geometry machining process, but also a physical machining process. Ensuring geometry accuracy, maintaining dynamic machining process stability and improving machining efficiency have been basic requirements of high performance machining. Therefore, taking high performance peripheral milling as research objective, predicting milling force, calculating geometric error and computing of machining process stability are studied.1、Introducing the cutter coordinate system, rotational coordinate system and workpiece coordinate system, the reason inducing the cutter runout is analyzed and the kinematic transformation basic rules of general machine are given. The transformation process of a point on the cutter edge from cutter coordinate system to the rotational coordinate system is derived. Subsequently, the rotational surface of the cutter edge about the spindle axis of machine is introduced. Simultaneously, the transformation principle of a point from rotational coordinate system to the workpiece coordinate system is derived.2、Cutting force prediction model, which is suitable for the five axis peripheral milling, is built. Using cutter location information and process parameters, the real sweep surface of cutter edge is processed. Then, the instantaneous uncut chip thickness model is developed. On the basis of this, the cutting force model is built, and then a coefficient detective model is proposed. Subsequently, cutter runout parameters are identified using the cutting force model and experimental results are showed. The predicted values computed by the proposed cutting force prediction model are compared with that of the classical method. Results show that the method in this paper is of higher accuracy. Finally, a series of three and five axis peripheral cutting force experiment are conducted to verify the validity, efficiency and accuracy of the proposed method.3、The geometry error induced by the cutter runout are introduced and the corresponding tool path compensation method is presented. Combining the general situation of the cutter runout, an arbitrary point’s velocity vector and normal vector on the cutter edge’s rotational surface about spindle axis are calculated. Utilizing the relationship between these two vectors and the envelope principle, the envelope-sweep surface along tool path is computed. Comparing the envelope surface with the machined surface, the geometry error induced by the cutter runout is calculated. Then the effect of the cutter runout parameters and the number of the cutter edges on the geometry error is studied. Finally, the error induced by the cutter runout is reduced significantly using the proposed tool path planning method.4、A new third-order full-discretization method to compute stability lobes of dynamic milling system is presented. Based on the mathematical model of chatter, the stability lobes of dynamic machining system are calculated using the above method and the convergence property of the method is discussed. Becsuse of the existence of the cutter runout, the chatter is not induced by single regenerative effect but multiple regenerative effect. Thus this paper gives the mathematical model of multiple regenerative effect and calculates conresponding stability lobes. Finally, the influence law of the cutter runout on the stability lobes is studied.Taking a typical scale workpiece as an example, the effectiveness of tool path planning method and stability prediction method are verified, and then the results are used to guide the machining process of the component. The results show that the accuracy of machined surface and material removal rate are improved. This meets the requirement of the high performance machining.