高速磨削18CrNiMo7-6齿轮钢对残余应力的影响研究

发布时间：2018-10-14 20:10

【摘要】：近年来,高速磨削技术的发展和研究受到广泛学者的关注和青睐。高速磨削技术的高效高质量加工,不仅能为国防军工、电力、铁路等各行业提供难加工的工艺技术,也对提高机械产品的精度、可靠性和寿命等起着十分重要的作用。此外,根据saloman曲线可知,高速/超高速磨削能越过“热沟”,减少磨削区产生的磨削热传入工件,避免或减少其表面“烧伤”,使表面获得残余压应力,从而使工件的疲劳强度得到提高。18CrNiMo7-6是制造齿轮、轴等重要零件的原材料,因其良好的力学性能和机械性能,普遍应用于航天航空、电力、石油化学、机械等各个行业。研究不同的高速磨削参数对齿轮材料18CrNi Mo7-6的残余应力及金相组织的影响,对于提高工件表面完整性和使用寿命具有重要的意义。本文以高速平面磨削探讨了18CrNiMo7-6渗碳淬火齿轮钢的高速/超高速磨削工艺技术与表面完整性(重点关注残余应力)之间的关系。通过设计合理的高速磨削加工试验方案及表面完整性检测方案,获取最佳磨削参数组合,为齿轮材料的表面完整性及疲劳寿命的研究提供数据支持。本文的主要研究内容如下:(1)设计了18CrNiMo7-6高速磨削工艺单因素试验方案:磨削参数的设置中,砂轮线速度的变化范围为60~160m/s,工作台速度为2~6m/min,一次磨削深度为10~50μm。(2)研究了金属磨削机理,并以此建立了单颗粒磨削有限元模型,使用AdvantEdge切削有限元软件中的三维弹塑性有限元技术和Power Law标准模型进行模拟仿真,分析了不同的切削速度和切削深度对试件残余应力的影响。(3)研究分析了高速磨削后工件的金相组织成分、晶粒度的变化,磨削后试件的表层组织由回火马氏体、小颗粒状碳化物和少量残余奥氏体组成,心部由低碳马氏体和粒状贝氏体组成。通过金相组织研究分析了残余应力的变化原因,为高速磨削对残余应力的影响研究提供了间接分析的试验依据。(4)研究分析了不同磨削参数对齿轮材料18CrNiMo7-6残余应力场分布的影响。试验和仿真结果表明:砂轮线速度对残余应力的影响最大,磨削深度和工作台速度的影响较小,且在V_s=120m/s时试件表面和基体中获得最大残余压应力。得到了最优磨削参数组合为:V_s=120m/s、V_w=4m/min、a_p=0.02mm。
[Abstract]:In recent years, the development and research of high-speed grinding technology has attracted the attention and favor of many scholars. The high efficiency and high quality machining of high speed grinding technology can not only provide difficult processing technology for national defense industry, electric power, railway and other industries, but also play a very important role in improving the precision, reliability and service life of mechanical products. In addition, according to the saloman curve, high speed / super high speed grinding can cross the "hot ditch", reduce the grinding heat from grinding area to workpiece, avoid or reduce the surface "burn", and make the surface obtain residual compressive stress. Therefore, the fatigue strength of workpiece is improved. 18CrNiMo7-6 is the raw material for manufacturing gears and shafts. Because of its good mechanical and mechanical properties, 18CrNiMo7-6 is widely used in aerospace, electric power, petrochemical, mechanical and other industries. The influence of different high speed grinding parameters on the residual stress and metallographic structure of gear material 18CrNi Mo7-6 is studied. It is of great significance to improve the surface integrity and service life of the workpiece. In this paper, the relationship between high speed / ultra high speed grinding technology and surface integrity (focusing on residual stress) of 18CrNiMo7-6 Carburizing quenched gear steel is discussed by high speed plane grinding. The optimum grinding parameter combination is obtained by designing reasonable high-speed grinding test scheme and surface integrity testing scheme, which provides data support for the research of surface integrity and fatigue life of gear material. The main contents of this paper are as follows: (1) the single factor test scheme of 18CrNiMo7-6 high speed grinding process is designed. In the setting of grinding parameters, the linear velocity of grinding wheel varies from 60 to 160 m / s, the speed of worktable is 2 ~ 6 m / min, and the grinding depth is 1 050 渭 m. (2) the mechanism of metal grinding is studied. The finite element model of single particle grinding is established, and the three dimensional elastoplastic finite element technique and Power Law standard model of AdvantEdge cutting finite element software are used to simulate the model. The influence of different cutting speed and cutting depth on the residual stress of the workpiece is analyzed. (3) the microstructure of the workpiece after high speed grinding, the change of grain size and the microstructure of the surface layer of the workpiece after grinding by tempering martensite are studied. Small granular carbides and a small amount of retained austenite are formed, and the core is composed of low carbon martensite and granular bainite. The reason of the change of residual stress is analyzed by metallographic study, which provides the experimental basis for indirect analysis of the influence of high speed grinding on residual stress. (4) the influence of different grinding parameters on the distribution of 18CrNiMo7-6 residual stress field of gear material is studied and analyzed. The experimental and simulation results show that the linear velocity of the grinding wheel has the greatest influence on the residual stress, while the grinding depth and the speed of the worktable have little effect on the residual stress, and the maximum residual compressive stress is obtained on the surface of the specimen and in the matrix during V_s=120m/s. The optimum grinding parameters are as follows: VS / S 120 m / s / V\ + / W\%\
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG580.6

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