基于边缘碎裂效应软推挤驱动裂纹刀伴随切削陶瓷机理

Aiming at the deficiency of high efficiency and low cost removal machining of engineering ceramics and other hard brittle materials, the new method of ceramic cutting accompany with crack knife with the action of soft broaching based on edge fragment effect was suggested. The basic principle is that based on the suspended structure, the soft tool push and drive the crack system. It is then expands and extends quickly to the surface, cut into chips and fall off inside the material. That is the three-dimensional "cutting" of crack knife. Via indentation fracture mechanics and damage mechanics theory, the mechanism of cutting accompany with crack knife was investigated, the expands of crack and the formation of chips during the push process was modeled, the intrinsic law of synergistic effect between the push and the crack knife was disclosed. The fractal feature of cracks' expanding path was studied, texture and morphologyfeatures of the processed surface were analyzed, the nonlinear mapping relationship between the formation of chips and surface quality was discussed. A comprehensive evaluation system focus on processing efficiency, cost, surface integrity and the safety of material was built. The multipleregressionanalysis and neural network were employed to predict the machine quality and the machine capability. To sum up, a new highly efficient and low-cost processing method for machining ceramics and other hard and brittle materials was provided.

针对目前工程陶瓷等硬脆材料缺乏大余量去除加工手段的工程实际，提出基于边缘碎裂效应的软推挤驱动裂纹刀伴随切削陶瓷的新方法，即在切割形成凸缘结构的基础上，用软工具推挤驱动裂纹系统启动，使其快速扩展并延伸到连续产生的边缘表面形成切屑脱落，从而实现"裂纹刀"伴随挤压过程的立体"切削"。根据压痕断裂力学和损伤力学理论探讨"裂纹刀"伴随切削机理，模拟推挤加工中裂纹扩展直至产生切屑的演变过程，揭示推挤力与"裂纹刀"间协同作用的内在规律。分析裂纹扩展路径的分形特征，研究加工表面纹理与形貌特征，探讨切屑形成与表面质量的非线性映射关系。构建以加工效率、成本、表面完整性以及材料安全性为主的多元综合评价体系。采用多元回归分析、神经网络等方法，实现对加工质量和加工性能的预测。为工程陶瓷等硬脆材料的高效、低成本加工提供新途径。

构建了基于边缘碎裂的切割-软刀推挤加工陶瓷的实验系统，开展了该新加工方法的系统基础试验。完成了用金刚石砂轮片切割预制缺陷-软刀轴向推挤加工陶瓷的工艺实验，通过对车刀主后刀面磨损量、轴向推挤力等加工参数的测量，考察预制缺陷的效果及其在外加推挤力的作用下裂纹扩展，以及加工参数对加工表面质量的影响规律。采用单晶压头挤压破碎模拟实验研究了陶瓷基于边缘碎裂的切割-推挤式加工的机理。完成了基于边缘碎裂的切割-推挤式加工的实验研究。通过单因素实验和正交实验着重研究槽深、凸缘厚度、进给速度三个加工参数对车刀磨损和轴向推挤力两项指标的影响规律。综合利用灰度共生矩阵和神经网络方法实现了已加工表面质量的非接触式评估。. 开展了基于裂纹扩展效应的陶瓷外圆切槽-推磨复合加工技术的研究。对切槽后的陶瓷凸缘表面/亚表面损伤层的形貌进行了观察分析，开展了切槽加工参数和推磨加工参数轴向与法向推磨力的影响规律的实验研究，以表面质量、加工效率和加工成本为评价指标，将Si3N4陶瓷切槽-推磨加工和传统磨削加工之间进行了对比分析，证实了切槽-推磨加工技术符合高效低成本加工技术的特征。. 开展了基于裂纹扩展效应的陶瓷切割-推磨复合式平面加工技术研究。以块占比为表征参数，得出不同壁厚下适于推磨的最小凸缘高度。选取推磨角、凸缘壁厚、推磨深度、砂轮转速、推磨速度5个工艺参数，采用金刚石砂轮完成了推磨加工正交实验。依据块占比、推磨力、表面粗糙度等表征参数，在对试验结果进行多元回归分析的基础上，研究了各工艺参数下裂纹扩展的规律及其对材料去除的效果，以及各工艺参数对加工表面质量的影响规律，检测了加工表面的残余应力，结合灰度共生矩阵，评估了砂轮的磨损。计算了该加工方法的材料去除率，结合加工表面质量，与传统的平面磨削加工进行对比，证明了该方法的高效、低成本性。