| Surface integrity induced by machining was a strong influence in the components’ performance and life in service. Recently the interest in magnesium(Mg) alloys from the transportation industries is increasing due to their low density and high specific strength. Plenty of researches focus on the cutting of this magnesium alloy, because of its wide range application in the automotive and aeronautics industries, but its unsatisfying surface integrity limits its application. How to improve its surface integrity with machining technology and optimized cutting parameters is becoming a research hotspot. Otherwise, to reduce the cost and time of experimental studies there are an increase use of the numerical simulation, being the FEM the most used amount other numerical methods.By taking AZ31 B magnesium alloy as the research object, this paper did orthogonal cutting test on the alloy in dry and cryogenic cooling conditions, built finite element simulation model of metal cutting, proposed an orthogonal experiment based on the results of simulation calculation for the study of influences induced by the change of cutting parameters and cooling conditions and the study of their significances. The research work mainly includes the following aspects:Firstly, this study accomplished orthogonal cutting test on the AZ31 B Mg alloy in dry and cryogenic cooling conditions and the measurement of the machined surface’s residual stresses. In order to validate the numerical model, cutting forces and the geography of the chip were also measured. The test changed the cutting parameters and cooling conditions individually and respectively to study their influences on residual stresses.Secondly, this study built finite element model of metal cutting for AZ31 B Mg alloy. The constitutive model and damage model of magnesium alloy and the friction model between the chip and tool were studied. The basic model was built in ABAQUS. Two tests had to be done for the determination of friction coefficient at the chip/tool interface and convection coefficient for cryogenic condition. Then, part of coding was done for transfer the dry cutting model to cryogenic cutting model. The simulation model should be validated with the results from the cutting experiment.Thirdly, this study proposed an orthogonal experiment based in the results of simulation. Compared with overall experimental method, the orthogonal method effectively reduced the amount of the experiments. This paper took the experiment on 4 factors with 5 levels in dry cutting condition and cryogenic condition respectively. By analyzing the results, this paper studied in the influences induced by the change of cutting parameters and cooling conditions and the study of their significances, and then came up with optimization scheme.Finally, this paper studied the energy efficiency of orthogonal cutting. The relation between cutting force and energy consumption was researched. The simulated results could show the values of cutting forces, which could avoid the complexity of application of traditional formula of cutting force. At the same time, the influences induced by cutting parameters on cutting forces could reflect their influences on energy consumption and energy efficiency. In conclusion, this model can be used for other metal cutting research in the condition where the material’s parameters and cutting parameters are effectively changed. |
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