柔性抛光方法中的磨粒群剪胀效应及划痕损伤控制方法

In softness polishing methods, abrasives group would randomly become ruinous cutting situation without strict control, which leads to unpredicted materials removal effect and scratch damage on the surface. Re-polishing processes have to be pushed forward for improving machining accuracy. This issue causes low efficiency of machining, especially in the process of dealing with freeform surface. Therefore, based on shear dilatancy effect of abrasives, a theoretic analysis method on ideal cutting situation of abrasives is presented for analysis of stress and kinesiology of abrasives. Meantime, the main factors will be concluded for change ruinous cutting situation of abrasives. Subsequently, a new scratch injury control method is presented. According to research on interwork between macro-factors and micro-factors, scratches mechanism will be discussed to restrain ruinous cutting situation of abrasives. And then, test platform will be built up for analyzing shear dilatancy effect of abrasives. Combined with stress-light theory and multicolor ladder-shape algorithm, the ideal cutting situation of abrasives and parameters for control will be obtained. In this case, optimization on bonnet polishing process to freeform surface of mould will be operated under available control method to improve machining accuracy and efficiency. Meantime, material removal mechanism of abrasives will be proved out. Our project has excellent meaning of scientific research and application and could be used as good reference for other softness polishing.

在各类柔性抛光方法中，非绝对约束下的磨粒群易随机形成破坏性结构，导致材料去除效果不理想和表面划痕损伤，需进行二次修复才能保证精度，这种现象在自由曲面加工中尤为突出，大大降低了加工效率。对此，本项目提出了基于剪胀效应理论的磨粒群理想切削状态理论分析方法，为柔性抛光方法中磨粒群的力学与运动学研究建立了理论基础，给出形成破坏性结构的主要影响因素；并在此基础上提出了划痕损伤控制方法，研究宏观参数与微观参数耦合作用规律，分析划痕产生机理，得出磨粒群破坏性结构主动抑制方法；搭建可模拟柔性抛光的磨粒群剪胀测控试验平台，结合应力-光学原理结合彩色梯度算法，对磨粒群理想切削状态及理想控制参数进行验证；对面向模具自由曲面的气囊抛光进行优化，并对磨粒群剪胀效应下的材料去除机理进行验证，实现加工质量和效率的提升。本项目的开展具有较好的科学研究价值与实际应用意义，可为各类柔性抛光方法优化提供借鉴。

针对柔性抛光中的磨粒群状态特性和可控性展开研究，提出了一种基于磨粒群剪胀效应磨粒群主动控制方法，针对软固结磨粒气压砂轮加工技术展开验证，提高了面向非一致曲率自由曲面的加工效率并减少了表面非受控性划痕损伤。主要成果如下：以多尺度力学分析方法展开了磨粒群剪胀效应下的力传递理论研究，基于软球模型建立了磨粒群微观接触模型，采用离散元分析方法，得出了力链结构的形成及演变规律，建立了磨粒群剪胀环境下的运动学模型；针对软固结磨粒群气压砂轮的加工特性，建立了磨粒群的材料去除预测模型：基于Hertz接触理论，建立磨粒群表面单颗磨粒的材料去除模型，并且基于断裂力学理论确定表面磨粒在粘磨层柔性支撑下的有效磨粒数，获得了不同参数粘磨层的材料去除预测模型；搭建了接触力测试试验平台，得到了不同状态下接触力的变化趋势；实时测试气压砂轮自动化光整过程接触力，建立了气压砂轮接触力性能的评价标准：搭建了气压砂轮加工试验平台，验证了材料去除模型；以提高加工加工效率和减少非受控性损伤为目标，优化了各类工艺参数。