基于仿真的AZ31B镁合金低温切削的表面完整性及能耗研究

发布时间：2018-06-29 00:30

本文选题：数值仿真 + 正交切削　；参考：《上海交通大学》2015年硕士论文

【摘要】：表面完整性对金属加工的机械部件的性能和疲劳寿命有很大的影响。而表面完整性又在很大程度上受到加工技术的影响。如何利用不同的加工方法与工艺改善材料的表面完整性已成为一研究热点。AZ31B镁合金因其低密度和高强度等优点,在汽车和航空领域有着广泛的应用,但其表面完整性却不尽如人意。不佳的表面完整性已成为阻碍镁合金更进一步广泛利用的一大因素。而通过改变加工条件则可以改善这一现状。另外,为了节约实验设备、材料消耗、时间等成本,在金属切削领域中,利用数值模拟的仿真模型来研究金属切削过程的实例在不断增加。在金属切削建模与仿真的研究上,有限元的应用则最为广泛。本文以AZ31B镁合金的切削过程为研究对象,完成了干切削及在液氮环境中的低温切削实验,建立了金属正交切削的有限元模型,利用正交试验法确定各试验组的切削参数,利用仿真模型计算得到各组切削参数下的切削力、表面残余应力等结果,最后通过数理统计方法计算研究各切削工艺参数以及冷却条件对工件表面完整性和切削单元能耗的影响趋势及影响显著性。本文的研究工作主要包括以下几个方面:首先,完成了AZ31B镁合金的干切削以及液氮喷射的低温切削实验。测量切屑的形状,切削力以及已加工表面的残余应力,用于之后校核验证仿真模型。实验通过分别单独改变切削速度、切削深度、刀具前角、刃口半径以及冷却条件的方法,研究了冷却条件和切削工艺参数对表面完整性的影响趋势。其次,建立了AZ31B镁合金的正交切削有限元模型。研究了AZ31B镁合金材料的本构模型和破坏模型以及切削仿真设计中切屑和刀具的摩擦模型。根据材料的破坏特性,在ABAQUS软件中建立了AZ31B镁合金正交切削的有限元模型;做进一步二次开发,利用编程,完成了低温切削的仿真模型。利用仿真模型的输出结果和实验的测量结果进行模型的准确性验证。第三,提出了基于仿真模型的正交试验法,用以研究各工艺参数对金属已加工表面完整性的影响显著性。本文采用四因素五水平正交试验,分别在干切削和低温切削条件下进行仿真试验计算,应用仿真结果,分析各个切削工艺参数对表面完整性的影响趋势及显著性。最后,研究了切削单元能耗。直接建立切削单元能耗和主切削力之间的关系,利用仿真模型结果中的主切削力,计算各试验组的切削单元能耗值。再次运用正交试验法,得出各工艺参数对切削单元能耗的影响趋势与显著性。
[Abstract]:Surface integrity has great influence on the performance and fatigue life of machined parts. The surface integrity is greatly affected by the processing technology. How to improve the surface integrity of materials by different processing methods and processes has become a research hotspot. AZ31B magnesium alloy has been widely used in automotive and aviation fields because of its low density and high strength. But its surface integrity is not satisfactory. Poor surface integrity has become a major obstacle to the wider use of magnesium alloys. By changing the processing conditions, this situation can be improved. In addition, in order to save experimental equipment, material consumption, time and other costs, in the field of metal cutting, the use of numerical simulation model to study the metal cutting process examples are increasing. Finite element method is widely used in metal cutting modeling and simulation. In this paper, the cutting process of AZ31B magnesium alloy is studied, the experiments of dry cutting and low temperature cutting in liquid nitrogen environment are completed, the finite element model of metal orthogonal cutting is established, and the cutting parameters of each test group are determined by orthogonal test method. The simulation model is used to calculate the cutting force and surface residual stress under various cutting parameters. Finally, the influence trend and significance of various cutting process parameters and cooling conditions on the surface integrity of workpiece and the energy consumption of cutting unit are studied by mathematical statistical method. The research work of this paper mainly includes the following aspects: firstly, dry cutting of AZ31B magnesium alloy and low temperature cutting experiment of liquid nitrogen injection have been completed. The shape, cutting force and residual stress of the machined surface were measured to verify the simulation model. The influence of cooling conditions and cutting process parameters on the surface integrity was studied by changing the cutting speed, cutting depth, cutting tool angle, cutting edge radius and cooling conditions separately. Secondly, the orthogonal cutting finite element model of AZ31B magnesium alloy is established. The constitutive model and failure model of AZ31B magnesium alloy and the friction model of chip and tool in cutting simulation design were studied. The finite element model of orthogonal cutting of AZ31B magnesium alloy is established in Abaqus software, and the simulation model of low temperature cutting is completed by further development and programming. The accuracy of the model is verified by the output of the simulation model and the experimental results. Thirdly an orthogonal test method based on simulation model is proposed to study the effect of various process parameters on the surface integrity of metal machined. In this paper, four factors and five levels orthogonal test are used to calculate the simulation results under the condition of dry cutting and low temperature cutting respectively. Using the simulation results, the influence trend and significance of each cutting process parameter on the surface integrity are analyzed. Finally, the energy consumption of cutting unit is studied. The relationship between the energy consumption of the cutting unit and the main cutting force is established directly. The energy consumption of the cutting unit in each test group is calculated by using the main cutting force in the results of the simulation model. The influence trend and significance of each process parameter on the energy consumption of cutting unit were obtained by orthogonal test method.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG146.22;TG506

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