Finite Element Simulation And Experimental Research On The Prestressed Cutting Of Titanium Alloy Ring Parts

As an important row material in aerospace industry, Titanium alloy has beenwidely used to manufacture the key parts in aeronautics and astronautics, theautomotive industry and the medical profession for its excellent performance includingsmall density, high specific strength and fracture-resistant characteristics. However,Titanium alloys show poor cutting performance, serrated chips are always generated incutting process, serious tensile residual stress distribution is found on the machinedwork surface. In order to improve the state of residual stress on the machined worksurface, the practice show that prestressed cutting method, which is a simple and cheapresidual stress adjusting way, can actively control the residual stress states of machinedsurface just in metal cutting process, it has complex and expensive stress adjustmentprocess after the cutting process could be omitted. A prestress extension device for ringparts is designed and manufactured, finite element analysis of prestressed cutting oftitanium is performed. Combining the methods of finite element simulation andexperimental validation, the prestressed cutting of Titanium alloys ring parts, the effectof pretress, cutting speed, cutting depth and feed rate on cutting force, chipmorphometric and machined surface integrity are revealed, it shows importantsignificance to systematically master the prestress cutting method and optimize theprocess parameters for titanium alloy.1. The background and significance of this research is introduced firstly. Thestate of the art in the research of prestressed cutting and application of finite elementmethod incutting process are summarized. The main contents and frame structure ofthis dissertation are discussed.2. The mechanism of residual stress induced in cutting process is analyzed, andrelevant theories of effects of residual stress on machined surface quality areinvestigated. The principle and characteristics of prestressed cutting processingmethod are illustrated by summarizing the residual stress adjustment method. APrestress extension device for titanium alloy ring parts is designed and manufactured.3. Based on the equations in finite element simulation and consideration ofelastic-plastic deformation in the process of cutting, several critical technique incutting simulation are considered, the arbitrary Langranian-Eulerian method andadaptive mesh technique are also researched. A2D finite element model forprestressed cutting TC4is established, the forming principle of serrated chip is furtherdiscussed, the effects of prestress on chip morphology, cutting force, cutting temperature and equivalent plastic strain as well as residual stress distribution arerevealed.4. A metal machining process are designed for titanium alloy ring parts,deformation caused by prestress loading and the compensatory method in cuttingparameters were discussed, results including residual stress, cutting force andchip morphology are verified by experiments. The machined surface integrity,such as surface roughness, surface hardness, and surface topography are analyzed.Finally, the pre-stressed cutting parameters are optimized, deformation caused byprestress loading and the compensatory method in cutting parameters arediscussed.5. The whole work and limitations are summarized; meanwhile the future workis discussed.