力热耦合作用下钛合金微结构表面高效创成的磨削方法研究

Micro structures can give the components surface of titanium alloy the physical characteristics of drag reduction, wear resistant and fatigue resistance, which can improve their application performance under the specific working conditions. In the project, the method of high efficient generation using grinding is proposed to obtain the micro structures surface of titanium alloy. This method can machine the micro structures surface and the macro profile of component at the same time. The involved investigative fundamental topics include mechanism of material removal, principle of micro structures surface generation, surface integrity of component and so on. The model of material removal is created to describe titanium alloy micro structures surface for non-uniform material removal volume. The influenced tendency is exposed to indicate the effect of coupling mechanical-thermal on the physical behavior of contact interface of abrasive and workpiece. The mechanisms of the parametric association between ordering grinding wheel and processing is deeply investigated for the generation of micro structures surface. The wear pattern and its evolution effect of electroplated CBN grinding wheel are also discussed in this project. The effect of grinding wheel topology and grinding process on the machining accuracy and surface integrity was analyzed. The following scientific problems are paid main attentions in this project: the dynamic transfer law for cutting behavior of abrasive grain under multi-source constraints; the effect of coupling mechanical-thermal on the surface integrity of ground workpiece, which provides the support for efficient generation of titanium alloy micro structures surface. Based on the requirement of generating of micro structures surface, the theory and method of designing ordering wheel surface and planning processing parameters are given, which can provide the theory support for generating the micro structures surface of titanium alloy using grinding.

微结构可赋予钛合金表面层减阻、耐磨、抗疲劳等物理特性，提高零件在特定服役环境中的使用性能。本项目提出钛合金微结构表面高效创成的磨削方法，可兼顾零件微观成性创成及宏观成形加工，围绕材料去除机理、微结构表面形成机制、表面完整性等方面开展基础科学研究，建立钛合金磨削表面非均匀材料去除量的数学模型，揭示力热耦合作用对磨粒与材料接触界面物理行为的影响规律，探索有序性砂轮形貌特征与磨削工艺对微结构表面创成的协同作用机制，研究电镀CBN砂轮磨损形式及其演化效应，分析砂轮形貌、磨削工艺对微结构表面创成精度及表面完整性的影响规律；重点解决多源约束下磨粒切削行为特征的动态传递规律、力热强耦合作用对零件表面完整性的影响机制等关键科学问题，借助磨削过程实现钛合金微结构表面的高效创成；形成涉及微结构表面特征的有序性砂轮形貌设计与工艺参数规划理论和方法，为钛合金微结构表面磨削的高效创成提供理论支撑。

微结构可赋予零件表面层减阻、耐磨、抗疲劳等物理特性，提高零件在特定服役环境中的使用性能。本项目提出微结构表面高效创成的磨削方法，可兼顾零件微观成性创成及宏观成形加工，围绕材料去除机理、微结构表面形成机制、表面完整性等方面开展基础科学研究。提出了有序化规则型砂轮形貌的生成方法，针对普通磨料砂轮和超硬砂轮，形成了砂轮形貌生成的修整路径规划或电镀流程；揭示了典型微结构表面的磨削创成工艺，面向筋条类、凹坑类、凸台类微结构表面，获得砂轮修整导程为60~240 μm、砂轮/工件速比为18、聚集系数为0.5、磨削深度为0.15 mm等关键工艺参数参考值，得到了上述工艺参数变化对微结构排布尺度、密度的影响规律。揭示了微结构磨削表面成形中力热影响因素，筋条表面面积占比不易超过30%，凹坑类微结构在表面分布越均匀，磨削产生的力和热越低，在规划凹坑类微结构时，应将不均匀率控制在20%以下，以同时满足磨削效率与质量。得到了微结构工件表面粗糙度、残余应力分布规律，磨削表面粗糙度随进给速度、修整深度的增大而增大，随转速比的增大而减小；工件表层至深度0.4 mm以内为拉应力，微结构特征越分布越均匀，其形成拉应力影响层越小。微结构表面试件的疲劳循环次数呈现降低的趋势，但结构特征分布均匀性愈好，其表面层疲劳强度受到的影响愈低；凹坑、筋条微结构表面的摩擦力低于光滑表面摩擦力值，凹坑结构表现出的摩擦力最低。形成了有关微结构应用和加工的学术论文、发明专利等成果。在完成项目研究内容的基础上，形成兼具零件宏观成形加工与微结构表面创成的砂轮型面结构、形貌特性设计与工艺参数规划的理论和方法。同时，项目研究过程中，将微结构呈现的优异服役性能引至钢轨表面，开始研究规则化钢轨纹理对摩擦、磨损、接触疲劳方面的影响，有效拓展了微结构的加工方法和应用领域。