基于剪切流变匹配调控磨粒簇射流的碳化钨模具抛光方法研究

Tungsten carbide has the advantages of high hardness, temperature resistance, corrosion resistance and chemical resistance. It is used as the optical mold material and plays an important role in the mass production of aspheric optics with high efficiency and precision. To overcome negative influence of the instability of the turbulent jet on the surface precision and quality, a new shear rheology matching adjusted abrasive clusters jet polishing method is proposed for tungsten carbide mold machining. The shear thickening fluid is used as the based fluid of the polishing slurry. Under the high shear stress on the high speed jet, the particle clusters are formed by the suspended particles in shear thickening fluid and the abrasive particles, which leads to the rapid rise of fluid viscosity. The high turbulent unstable jet is thus changed to a low turbulent stable particle clusters jet. The stability of the material removal function is improved, as well as the surface precision and quality of the tungsten carbide mold after polishing. In this project, the shear rheological matching mechanism of polishing slurry in the impact jet flow is investigated. The synergistic effect between the non-newton shear stress and the erosion of particles clusters in the material removal process is analyzed. Moreover, the influence of shear matching rheology on the surface precision and quality after polishing is elaborated. The investigations will be beneficial for improving the polishing efficiency and surface integrity of tungsten carbide mold, and contribute to the basic theory of fluid jet polishing.

碳化钨具有超高硬度、耐高温、耐腐蚀、化学性能稳定等优点，是一种新兴的玻璃模压成型模具材料，在非球面光学元件大批量、高精高效制造过程中发挥着重要作用。围绕碳化钨模具光学表面超精密加工需求，针对常规射流抛光技术中射流束的紊动与发散降低模具表面加工精度与质量问题，提出剪切流变匹配调控磨粒簇射流抛光新方法：以剪切增稠流体为基液配置抛光液，通过冲击射流壁面剪切率与抛光液流变区间之间的匹配调控，促使剪切增稠悬浮粒子包裹磨粒形成磨粒簇，提高射流粘度，将高紊动、发散的磨粒射流转变为低紊动、聚集的磨粒簇射流，从而提升去除函数稳定性，实现模具表面高质量抛光。本项目通过理论分析、数值模拟和实验研究，揭示冲击射流下非牛顿流体剪切流变匹配机理，分析材料去除过程中非牛顿剪切应力与磨粒簇冲蚀的协同作用，探究剪切流变效应对表面精度与质量的影响规律。本课题研究成果将有助于提升非球面光学模具制造水平、丰富射流抛光的基础理论。

本项目围绕硬质光学模具表面超精密加工需求，针对常规射流抛光技术中射流束的紊动与发散降低模具表面加工精度与质量问题，提出了剪切流变匹配调控磨粒簇射流抛光新方法。在分析磨料流流体模型、去除模型基础上，通过仿真模型分析了剪切增稠和剪切稀化流体的流场分布特性，分析了流变效应对材料去除的影响规律；探索了剪切增稠抛光液的配置方法，配备了多种规格的抛光液，分析了抛光液成分对剪切增稠流变特性的影响；搭建了采斑与抛光工艺试验平台，开展了剪切增稠抛光液与牛顿流体抛光液的采斑对比实验，发现了剪切流变与射流剪切速率的匹配特性，揭示了剪切流变对抛光去除效率以及抛光斑形态特征参数的影响规律，并完成了面型抛光工艺试验验证，获得了高质量的光学表面。本课题研究成果将有助于提升硬质光学模具抛光技术发展，并可丰富流体超精密抛光的基础方法理论。