齿根亚表层残余应力控制及表面完整性制造基础研究

High performance gear manufacturing widely used carburizing and quenching gear grinding process.gear is grinding only on the surface and not at the root, In order to preserve the residual compressive stress at the tooth root after carburizing and quenching. But there not grinding tooth root often influence strength and geometrical morphology of the oxidation of tissue.This project aims to according to the gear bending fatigue failure form, by numerical simulation, the innovation of residual stress measurement, fatigue test and other methods, to reveal the root grinding residual stress and surface morphology of bending fatigue strength, influence of surface integrity, rationality and feasibility evaluation of grinding tooth, optimization of processing technology and technical parameters; at the same time, to strengthen the research of fine control of shot peening and shot peening on new tooth, explore the different diameter of the projectile with different shot peening and shot peening intensity has high strength after the first two shot peening on low strength Effect of surface integrity, solve root grinding, heat treatment hardening after the shot peening to introduce compressive residual stress to improve the residual stress state of the tooth surface, based on fatigue strength for the surface integrity evaluation system of final judgment standard, the comprehensive test of gear bending fatigue strength increase 20%-50%. finally establish a bend fatigue strength as the ultimate criterion of dedendum surface integrity of manufacturing system, make to lay a solid foundation for high performance gear fatigue resistance.

高端齿轮制造普遍采用渗碳淬火+磨齿工艺，国内齿轮磨齿时一般只磨齿面不磨齿根，目的是保留渗碳淬火后齿根处的残余压应力，但不磨齿根往往存在影响强度的内氧化组织和几何形貌。本项目拟根据齿轮弯曲疲劳失效机理，采用数值模拟、残余应力分析、弯曲疲劳实验等方法，揭示齿根磨削后残余应力及表面微观形貌对齿轮弯曲疲劳强度、表面完整性的影响规律，综合评估磨削齿根的合理性和可行性，优化齿轮磨削加工工艺和参数；同时，对齿根进行精细控制喷丸和新喷丸强化技术研发，研究不同弹丸直径与不同喷丸强度的先后喷丸强化以及先高强度后低强度喷丸的二次喷丸强化对齿根残余应力分布的影响，探索齿根磨削后再采用精细控制喷丸来引入残余压应力以改善齿根亚表层残余应力分布状态的问题，进一步提高齿轮的服役寿命，使试验齿轮弯曲疲劳强度综合提高20％-50％；最后建立以弯曲疲劳强度为最终判据的齿根表面完整性制造体系，为高端齿轮抗疲劳制造打下坚实基础。

齿根弯曲疲劳折断是一种典型的齿轮失效形式，残余应力是影响齿根弯曲疲劳性能的重要因素之一。齿轮根部残余应力精确测量、齿轮复杂异形曲面残余应力沿深度分布状态的精确控制、残余应力影响系数确定及齿轮弯曲疲劳寿命预估等是基于残余应力研究齿轮抗弯曲疲劳制造技术的关键技术问题。因此，项目从五个方面进行研究：（1）根据布拉格方程、材料弹性理论以及X射线衍射原理推导齿轮齿根横、纵向残余应力关系方程，得出通过测定纵向残余应力来推算横向残余应力的方法，为深入了解齿轮根部残余应力精确分布状态提供了依据。（2）针对齿轮根部复杂轮廓曲线，通过分析齿根形状和曲线方程特点，根据啮合理论和轮齿成形原理，利用电化学原理和法拉第定律，得出用简单曲线预定义复杂轮廓曲线计算抛光时间和深度的关系，通过精确控制抛光时间控制抛光深度，从而实现齿根残余应力沿深度分布状态的精确控制，为进一步研究复杂零部件残余应力深度值的精确控制问题提供了理论支撑。（3）针对喷丸滚压复合强化工艺展开有限元仿真和实验分析，得出复合工艺可提高材料表层残余压应力，从而提高材料疲劳强度，提高材料表面质量，使其达到镜面效果，为深入探究复合强化工艺在齿轮抗疲劳制造领域的应用提供了依据。（4）基于裂纹扩展理论和线性损伤累积理论，根据Goodman关系，将残余应力当做平均应力处理，得出可通过齿轮S-N曲线求解残余应力影响系数m值的结论。在此基础上，通过m值推导出的喷丸齿轮弯曲S-N曲线和通过疲劳试验所得的S-N曲线趋势基本一致，且在高周疲劳情况下，计算所得的应力寿命数据更加安全。（5）对齿轮齿根磨削工艺进行实验研究，对比分析了未磨齿根和磨削齿根两种状态齿轮的金相组织状态、表面残余应力及残余应力沿深度变化情况等，为进一步优化齿根磨削工艺和展开齿根磨削工艺有限元分析提供了理论支撑和实验基础。