Action Mechanism Of Cutting Tool Edge And Application In Precision Machining Ti6Al4V

Titanium alloys Ti6Al4V, as a kind of light alloy with excellent overall performance have been used widely in aerospace industry in recent years owing to their superior properties, such as excellent strength-to-weight ratio, high corrosion resistance and ability to retain high strength at high temperature. In aerospace industry, in order to improve the performance and quality, stability and reliability of air products, and increase interchangeability between parts as to improve production efficiency, the aerospace parts require high machining accuracy and surface quality, and thus it puts forward higher requirements for precision machining technology of these parts.In precision machining Ti6Al4V, the scales of cutting parameters and tool geometry characteristic affect the process simultaneously, which leads to the specificity of cutting mechanism. Tool edge area is the main locations involving cutting process. The physical properties, mechanical strength, and geometric parameters play a crucial role in chip formation and characteristic of cutting force and temperature. Compared with conventional cutting, the area involving cutting process in rake face decreased in precision machining. Cutting tool edge will assume the work of material removal. Precision cutting mechanism changed and unit cutting force increased significantly. The thermal-mechanical distribution all concentrate in tool edge. Cutting tool edge has great effects on cutting process. The effects of tool edge structure and parameters on cutting deformation and material removal cannot be ignored. The action mechanism of tool edge has become one of the key issues to be solved in precision machining. Therefore, the present study aims at studying the action mechanism of tool edge and application when precision machining Ti6Al4V. This can provide theoretical basis for cutting mechanism of precision machining difficult-to-cut material such as Ti6Al4V and promote the development of precision machining theory and tool edge design.An experimental investigation is presented to study the effects of cutting parameters on chip shape and micro-morphology of serrated chip. The cutting conditions that tool edge work on in machining process can be determined by the research results. The tool edge geometry parameters were measured by laser scanning microscopy. The effects of cutting edge preparation on chip formation were studied using FEM and experiments based on the measurement of tool edge, in order to reveal the chip formation mechanism when incorporating tool edge in precision machining Ti6Al4V.The orthogonal cutting force model incorporating tool edge (round edge and chamfering edge) was established in precision machining Ti6Al4V in the light of classical cutting model. Simulation and experiments have been conducted to study the characteristic of cutting force incorporating tool edge. The established cutting force model and researches results of cutting force can predict the initial flow of chips, and fully reflect the relationship between tool edge and cutting force, and then provide theoretical basis for evaluating cutting performance and optimization design of tool edge.According to the researches of thermal generation and thermal conductivity, the average temperature model incorporating tool edge radius at shear band, tool flank face and rake face was established. The temperature distribution and the effects of tool edge (rounded edge and chamfer edge) on the thermal features and temperature variation in cutting Ti6Al4V process was studied using FEM and precision cutting experiments. The thermal characteristic was obtained through studying the effect of tool edge on cutting temperature.The cutting thickness model incorporating tool edge radius was established to determine the position where chip and workpiece separate. Based on studying the effects of tool deformation on cutting thickness, the minimum cutting thickness model was established in precision machining titanium. The two-dimensional cutting experiments were conducted to verify the effectiveness of established model. At last, according to the research results of the action mechanism of tool edge and minimum cutting thickness, the process of cutting titanium diaphragm disk incorporating tool edge was studied. The selected tool edge and cutting parameters can increase the surface quality and accuracy of titanium diaphragm disk.