球轴承滚动体螺旋孔型斜轧宏微观变形与损伤行为研究

发布时间：2018-09-02 08:32

【摘要】：滚动轴承是高速铁路、高速精密机床和冶金轧机等重大装备技术领域的核心配套部件之一。但目前国内生产的滚动轴承还无法较好的满足上述重大装备领域高速、重载等恶劣服役工况。滚动体作为滚动轴承关键组件,其成形制造技术水平直接影响着滚动轴承的动态性能、可靠性和服役寿命。螺旋孔型斜轧(斜轧)是目前生产轴承滚动体零件的一种优质、高效塑性加工技术。但斜轧工艺设计和变形机理复杂,成形精度和组织性能也还缺乏科学、有效的调控方法,都致使其无法较好的服务于高性能滚动体的成形制造。本文以钢球滚动体的热斜轧成形为研究对象,通过解决建模仿真中轧辊精确建模方法、仿真平台选择、轧件畸变、网格划分、求解参数设置等关键技术问题,基于SIMUFACT建立了轴承钢球热斜轧三维宏微观有限元仿真模型。基于模拟结果,揭示了钢球热斜轧成形过程塑性应变、温度、轧制力能参数、相对滑动与磨损、动态再结晶、静态再结晶和晶粒尺寸等宏微观变形规律。针对钢球热斜轧心部损伤,通过研究应力场的分布和演变特征阐明心部损伤是心部区域较高水平的横向拉应力、循环交变的剪切应力和多向拉应力为主的负静水压应力状态共同作用的结果。在此基础上,从不考虑静水压应力下损伤增长和基于Zener-Hollomon系数耦合变形温度与应变速率影响两个方面,改进了Lemaitre损伤模型。同时进一步借助SIMUFACT二次开发技术,将改进损伤模型嵌入到有限元模型中,建立了钢球热斜轧损伤预测模型。轧辊轧制孔型和轧制工艺参数对钢球热斜轧作用机制的研究结果表明:本文提出的幂指函数凸棱高度变化特征孔型方案能轧制出成形精度更高、晶粒尺寸更细的球坯;过高或过低的轧制温度和过大或者过小的轧辊倾角均会降低轧制成形精度;球坯晶粒尺寸和轴心区域损伤均对轧制温度较为敏感,随轧制温度的升高,晶粒尺寸呈现显著的粗化,心部损伤程度大幅增加。研究结果能为钢球滚动体热斜轧的控形与控性成形提供有效指导。
[Abstract]:Rolling bearing is one of the core parts of high-speed railway, high-speed precision machine tool and metallurgical mill. But at present, the rolling bearings produced in our country can not meet the high speed, heavy load and other bad service conditions. As the key component of rolling bearing, the level of forming and manufacturing technology directly affects the dynamic performance, reliability and service life of rolling bearing. Spiral pass cross rolling (cross rolling) is a kind of high quality and high efficiency plastic machining technology for producing bearing rolling parts. However, the cross rolling process design and deformation mechanism are complex, the forming accuracy and microstructure and properties are also lack of scientific, effective control methods, so that it can not be a better service for the forming and manufacturing of high performance rolling body. In this paper, the hot cross rolling forming of steel ball rolling body is taken as the research object. By solving the key technical problems in modeling and simulation, such as the precise modeling method of roll, the selection of simulation platform, the distortion of rolling piece, the mesh division, the solution of parameter setting, etc. Based on SIMUFACT, a three-dimensional macro-micro finite element simulation model for hot cross rolling of bearing steel balls is established. Based on the simulation results, the macro and micro deformation rules such as plastic strain, temperature, rolling force and energy parameters, relative sliding and wear, dynamic recrystallization, static recrystallization and grain size were revealed. In view of the damage to the center of hot cross rolling steel ball, the distribution and evolution characteristics of stress field are studied. It is shown that the damage of the center is a high level of transverse tensile stress in the center region. The result of the interaction between cyclic shear stress and multi-direction tensile stress in the negative hydrostatic stress state. On this basis, the damage growth under hydrostatic stress and the influence of deformation temperature and strain rate based on Zener-Hollomon coefficient are taken into account to improve the damage model of Lemaitre. At the same time, the improved damage model is embedded into the finite element model with the help of SIMUFACT secondary development technology, and the damage prediction model for hot cross rolling of steel balls is established. The effect of rolling pass and rolling process parameters on hot cross rolling of steel ball is studied. The results show that the feature pass scheme proposed in this paper can roll the billet with higher forming precision and finer grain size. Too high or too low rolling temperature and too large or too small roll inclination angle will reduce the rolling forming precision, the grain size and the damage in the axial zone of the ball blank are sensitive to the rolling temperature, and the rolling temperature increases with the increase of rolling temperature. The grain size showed obvious coarsening and the degree of heart damage increased significantly. The results can provide effective guidance for shape control and controlled forming of rolling body.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG335.17;TH133.3

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