Multi-scale Characterization And Simulation Of The Milling Surface Topography

Supported by the National Basic Research Program of P. R. China "Research on Key Scientific Issues of Super Large and Low Power Consumption Complex Air Separation Equipment" (973 Program, No.2011CB706505), and the National Science Foundation of China ’Theory and Method for Tolerance Design Based on the Parallel Decomposition of Function-Structure" (51275464). The thesis proposes a multi-scale modeling method for the rough workpiece, constructs the geometrical and physical model of the milling process, develops a multi-scale simulation method for the milling surface topography, and presents a modal factors based characterization method for roughness topography of the milling surface.In chapter 1:The history and latest progress of researches on the multi-scale characterization methods for the surface topography, modeling methods for the multi-source errors in the machining process and technologies for the prediction of the milling surface topography are reviewed. The research backgrounds and significances of the thesis are analyzed, and the research contents and general framework are presented.In chapter 2:Proposes a multi-scale characterization method for the workpiece surface; developed a new multi-scale modeling method for the workpiece surface based on the Improved Discrete Modal Decomposition method. By meshing the surface into multi-scale grids, generating the normalized modal vectors, generating the geometrical error factors, generating the dimensional error factors, mixing each scale of deviations, the multi-scale geometrical model of the workpiece is constructed, and the calculating time and precision are balanced.In chapter 3:With different tolerancing principles, the deviation factors of the multi-scale characterization model of the workpiece could be quite different. To solve this problem, with considering the tolerancing principles, generating methods for the geometrical and dimensional deviation factors of the workpiece are propoed in this chapter. Based on those methods the tolerance information and the geometrical model of the workpiece are unified.In chapter 4:By investigating the calculating method for the locating errors with considering the geometrical errors of the datums, analyzing the effects of the geometrical errors of the machine tool, spindle errors, and the errors caused by the cutting parameters on the precision of the finished workpiece, the cutting tool-workpiece engagement boundries are proposed with considering the effects multi-source errors, and the geometrical and physical model of the milling process are developed. Based on the static and dynamic model of the cutting tool, the geometrical model of the milling surface is further modified by the static parts and dynamic parts of the tool deflection. And in result, the multi-scale geometrical features of the milling surface are presented. At the end of this chapter, experiments are carried out to demonstrate the proposed methods.In chapter 5:By simulating the surface topography under different cutting parameters, the relationships between cutting parameters and the roughness value Ra are revealed. And to further describe the surface in detail, this chapter developed a modal factors based characterization method for surface topography of the milling surface, which not only can be used to represent the irregularity of the surface, but also reflect the effects of the cutting parameters on the milling surface.In chapter 6:A software system for multi-scale simulation and analysis of the 5-axis ball-end milling surface is developed based on MATLAB. Measurements about the geometrical errors of the mechine tool, cutting force coefficients and the modal parameters of the cutting tool are conducted based on a MIKRON UCP 600 5-axis ball-end mill.In chapter 7:The research contents and innovations of the thesis are summarized and the future prospects of related research topics are prospected.