硬脆材料零件复杂曲面的强约束磨粒射流抛光方法研究

Aim to the existing problem of jet divergence and impact damage in abrasive jet polishing for complicated surface of hard-brittle material parts, a mandatory constraint abrasive jet polishing method is proposed. The mandatory constraint is imposed to abrasive jet by the polishing tool and the preload system. This method changes the way of the abrasive jet formation and working, the normal spray processing of the loose abrasive jet is changed to the tangential shear processing of the mandatory constraint abrasive jet. Not only strengthen the shear of the abrasive particles on the workpiece surface, which improves the polishing efficiency, but also weaken the normal impact of the abrasive particles on the surface of the workpiece, which reduces the impact damage. Moreover, the problem of the jet divergence is solved, which improves the polishing precision. The minimum ultrafine nozzle is not necessary for realizing the jet machining. Based on fluid mechanics, tribology theory and surface analysis techniques, the formation conditions and the flow field characteristics of the mandatory constraint abrasive jet are studied, to ensure that the flow field characteristic parameters have good controllability. The mechanism of material removal is revealed and the function of the material removal is established. The experimental platform is constructed, then some typical samples are being polished. The influence law of the polishing efficiency, machining accuracy, surface quality and surface damage affected by the process parameters have been summarized, thus a theoretical foundation for low surface damage and high efficiency polishing for the complicated curve surface of hard-brittle material is provided.

针对磨料射流抛光硬脆材料零件复杂曲面过程中射流束发散与冲击损伤的问题，提出强约束磨粒射流抛光加工新方法，通过抛光工具头与预压力系统，改变了射流形成与加工的原理,将松散的磨粒射流法向喷射的加工方式改变为强制约束的磨粒射流切向剪切的加工方式，强化了磨粒对工件表面的剪切作用，提高了抛光效率，弱化了磨粒对工件表面的法向冲击作用，最大限度的减小了冲击损伤；而且解决了射流束发散的问题，提高了抛光的精度；无须极小极细的喷嘴即可实现射流加工。基于流体力学、摩擦学理论与表面分析技术，研究强约束磨粒射流的形成条件与流场特性，保证流场特征参数具有良好的可控性；揭示材料去除机理，建立材料去除函数。构建实验平台，进行典型试样的抛光实验，分析工艺参数对抛光效率、加工精度、表面质量与表面损伤的影响规律，为实现硬脆材料复杂曲面零件高效、低损伤、超精密抛光奠定理论和工艺基础。

传统方法抛光硬脆材料曲面时精度低，面形精度难以保证，而磨粒射流加工存在射流束发散与冲击损伤的问题，为此，提出“强约束磨粒射流”抛光硬脆材料曲面的方法。研究硬脆材料曲面“强约束磨粒射流”抛光的形成条件，建立了“强约束磨粒射流”流场特征参数的计算模型和流场特征参数的控制模型。构建了“强约束磨粒射流”抛光实验平台，采用理论研究和实验相结合的方法探索了抛光典型硬脆材料曲面的加工机理，初步确定了一定加工条件下的材料去除函数模型和工艺参数，为实现可控的“强约束磨粒射流”抛光硬脆材料曲面奠定理论和工艺基础。硬脆材料曲面的低损伤、超精密抛光一直是制造业的难题，也是控制生产成本的关键所在，确定了强约束磨粒射流抛光方法的材料去除函数，就可以通过控制策略和误差补偿手段实现确定性抛光硬脆材料曲面，这对提高抛光精度，修正曲面的面形精度意义重大。初步探索出一定条件下的强约束磨粒射流抛光工艺，对提高硬脆材料曲面的抛光效率，降低抛光成本有重要现实意义，若能实现产业化，有可预见的经济前景。