镍基高温合金高效抗疲劳磨削加工工艺及机理研究

In the grinding process of nickel-based superalloy, the coolant is not easy to approach the grinding zone to fully cool and lubricate the grinding surface and wheel. Significant residual tensile stress exists on grinding surface, the grinding efficiency is thereby limited, and the machined surface integrity is difficult to guarantee which will weaken the fatigue life. With a view to anti-fatigue machining and efficient grinding, an efficient anti-fatigue grinding methodology is put forward based on the combination of the pressurized inner cooling of wheel, prestressed machining and intermittent grinding methods. The coupled method for FEM and DEM models will be explored; a FEM model for simulating the grinding process and a DEM model for analyzing the frictional and wear behavior of wheel are going to be established respectively. According to the theoretic calculation, grinding test, FEM-DEM simulation, test analysis, fundamental theory and critical technique of efficient anti-fatigue grinding of superalloy will be studied, the comprehensive influence mechanism of prestress, coolant and grinding process parameters on surface integrity characteristics including residual stress, surface roughness and hardness together with wheel wear behavior will be revealed, grinding wheel life will be forecasted, experimental tests of fatigue strength for the grinded parts will be carried out, grinding process parameters will be optimized to improve both the grinding efficiency of wheel and fatigue life of superalloy, the relationship model and the corresponding appraisal system are going to be developed, which will promote the anti-fatigue machining technology for nickel-based superalloy.

镍基高温合金在磨削过程中，冷却液不易进入磨削区对磨削表面和砂轮进行冷却，零件表面分布严重的残余拉应力，磨削效率受到限制，加工表面完整性难以保证。从抗疲劳制造和高效磨削的观念出发，提出一种将砂轮加压内冷却、预应力加工和断续磨削三者集成于一体的高效抗疲劳磨削新技术理论和方法；研究有限元-离散元的过渡层耦合方法，建立模拟和分析高温合金预应力磨削过程的有限元模型以及砂轮-磨屑摩擦磨损行为的离散元模型；通过理论计算、加工实验、数值模拟、测试分析等，开展镍基高温合金高效抗疲劳磨削的基础理论和关键技术研究，阐明预应力、冷却液以及磨削加工参数对表层残余应力、表面粗糙度和表层硬化等加工表面完整性指标特征和砂轮摩擦磨损行为的影响机理，预报砂轮使用寿命；针对磨削加工后的零件开展疲劳强度实验研究；实现工艺参数的优化匹配，建立砂轮磨损-工艺参数-加工表面完整性的关系模型及评价体系，推动高温合金抗疲劳制造技术的进步。

镍基高温合金零件在磨削过程中产生大量磨削热，磨削液因气障效应和膜沸腾传热进入磨削弧区困难，难以有效对工件表面和砂轮进行强化换热，导致磨削效率受到限制，加工精度和表面完整性难以保证。项目结合内冷却方法、开槽间断磨削方法以及磨削液加压技术，提出了一种加压内冷却间断磨削方法，显著提高冷却、润滑和冲刷效果。项目通过理论计算、3D打印模型验证、加工试验、数值模拟和测试分析等，优化了冷却方式、磨粒排布、内流道结构和流道出口等砂轮结构参数，设计制备了具备可调可换磨料环的加压内冷却开槽砂轮，搭建了加压内冷却系统及试验平台，阐明了工艺参数对镍基高温合金磨削过程和加工表面质量的影响规律，实现了镍基高温合金磨削过程的强化换热和高效高质加工，推动了航空材料抗疲劳制造技术的进步。