Prediction Of The Cutting Force In Five-axis Flat End Milling Wide Strip Machining Of Sculptured Surfaces

With the development and application of the advanced CNC machine tools, especially five-axis CNC machining centers, as well as the innovation of complex surface processing methods, the method of five-axis flat end milling wide strip machining of complex surfaces has become a trend, which improve processing efficiency in actual production. During complex surface milling, milling force is an important physical parameter, which is directly related to milling vibration, cutting deformation, cutting heat and surface quality, and indirectly affects the machining accuracy of the workpiece and the cost of production. Therefore it requires deep study of prediction of the cutting force in five-axis flat end milling wide strip machining of sculptured surfaces, establishing the appropriate milling force prediction model, which has important theoretical and practical significance. This paper focus on the prediction of the cutting force in flat end milling wide strip machining of sculptured surfaces, especially the study of cutter workpiece engagement(CWE), the effective cutting edge interval and the milling force model. The following are the contents:1) A suitable cutter engagement model is presented in this paper. For the changing of CWE of machining, the curved surface machining is considered as a series of inclined surface machining, which is based on the differential discrete thinking. The workpiece coordinate system, inclined plane coordinates and the tool coordinate system are established. Also based on the idea of differential, the cutting depth is considered as a superposition of many cutting slice. And then the analytic cutter engagement model is established by getting the geometric information of CWE on each thin layer. Finally, by analyzing the movement geometric information of machining tool axis and surface processing, the CWE semi-analytic model is established on micro inclined plane, and then the CWE analytic model for the flat end milling wide strip machining of complex surfaces can be established.2) The calculation method of cutter engagement effective interval is presented in this paper. Based on the established CWE analytic model, the corresponding judgment of cutter edge engagement is put forward by analyzing the shape of CWE. The calculation method of cutter engagement effective interval bounds is presented by analyzing the positional relationship between the tool curve and CWE boundary curves during rotation of the flat end mill. And then the program of cutter engagement effective interval for the flat end milling wide strip machining of complex surfaces is developed.3) Milling force prediction model is presented in this paper. Based on the micro element cutting force model and undeformed chip thickness model, milling force prediction model of the flat end milling wide strip machining of complex surfaces is established on the tool coordinate system. We get discrete cutter locations of the tool path through the discrete sampling. And then the slope tilt angle and feed direction angle of each discrete cutter location point on the tool path can be obtained. Milling force prediction model on the workpiece coordinate system is presented through rotation conversion. The validity of cutting force prediction method proposed in this paper is confirmed through the actual milling experiment of the flat end milling wide strip machining of complex surfaces.