机械刻划衍射光栅铝膜材料的滞留效应及槽面非线性变形的抑制方法研究

The original ruled diffraction grating of large area is the core optical components of high-power lasers and high-resolution spectrometer,and the optical instrument performence is decided by the grooves quality of the mechanical ruled grating with low line-density and large area. To solve the problem of nonlinear deformation on the grating grooves surfaces during the mechanical ruling grating with low line density and large area, the task is provided. From the theory of stagnant zone and separation point of cutting tool of large negative rake angle, based on the new slip-line field thoery with stagnant zone ,the revolution process and the corresponding effect of the aluminum stagnant zone in front of the rake face are researched to present the forming mechanism of the elastic-plastic deformation separate line on the groove surface. The mathematic model among the tool-material forces, the slippery boundary shearing stress strengh of the aluminum stagnant zone,and the tension stress or compression stress of the grooves surfaces is set up. Then, the material mechanics criterion of the nonlinear deformation of groove surface is provided, and the extent of nonlinear deformation can be suppressed by optimizing the process parameters to improve the quality of grating grooves. Based on the modification of the nano test platform of three coordinates, the technichal experiments and tests of mechanical ruling grating will be completed and the relative regularities are concluded to verity the theoretical analysis. So that the suppression method of nonlinear deformation on the grating groove surfaces can be put forward to improve the groove forming quality. The achivements in this work will provide scientific guidance for the technical improvement of grating coating and mechnical ruling.

大面积原刻衍射光栅是高功率激光器和高分辨率光谱仪器的核心光学元件，机械刻划低刻线密度、大面积衍射光栅的槽形质量直接决定光谱仪器的性能。针对低刻线密度、大面积衍射光栅机械刻划过程中的槽面非线性变形问题，本课题从大负前角刀具切削过程中的滞留区和前刀面分流点理论出发，基于滞留区新型滑移线场理论研究机械刻划过程中刻刀前刀面处铝膜材料滞留区的演变过程和滞留效应，揭示光栅槽面的非线性变形及弹塑性变形分区机理；并建立刻划过程中刀具对铝膜材料作用力与铝膜滞留区滑移边界剪切强度和槽面上拉、压应力之间的数学模型；以此为基础，提出槽面非线性变形的力学临界判据，进行工艺参数优化；基于纳米三坐标测试平台的改进，实现衍射光栅刻划工艺试验和检测研究，总结相关规律，校正理论分析，提出光栅槽面的非线性变形的抑制方法，从而提高槽面成形质量。为光栅镀膜工艺和机械刻划工艺的改进提供科学指导。

为了从滞留效应的角度寻求提高机械刻划衍射光栅槽形质量的方法，首先基于流屑平面内正交切削过程的有限元模拟和实验，分析了大负前角金刚石车刀对纯铝材料作用过程中由切削到犁切挤压的临界力学转变过程和特征；然后结合机械刻划过程的塑流平面内滞留区滑移线场解析建模和三维刻划模拟分析，揭示了机械刻划过程中铝膜材料滞留区的产生机制，描述了滞留效应对刻划槽形的影响。最后建立了滞留区尺寸求解模型，分析了滞留区形态的演变过程和分布特征，结合有限元刻划过槽过程的剖视图分析揭示了滞留效应影响光栅槽面非线性变形及弹塑性分区的产生机理。基于塑流平面内滞留区特征滑移线场模型，建立了相关力学模型；并结合刀刃钝圆作用下的赫兹弹塑性力学理论进行了已成槽表面弹塑性变形分区的弹性回弹、应力特征分析和建模计算；然后基于刻划方向特征平面的滑移线场模型和上限法模型分析，建立了三向作用力模型，分析了工艺参数对槽面非线性变形影响的影响规律。通过对钝角、直角、锐角三种槽形角的槽面过挤压临界变形点的滑移线场力学建模分析，建立了机械刻划光栅过程中槽面非线性变形的力学极限载荷临界判据；研究了主要工艺参数对槽面非线性变形的影响规律，优化了相关工艺参数。借鉴纳米三坐标测量仪功能，开发了一种机械刻划工艺试验装置，搭配了激光衍射对刀功能和在位光学图像检测功能，可以实现刻划工艺的开放性实验和刻划性能评价；通过刻划实验，获得了槽面滞留分区的分布特征，验证了相关理论分析，结合刀刃钝圆效应修正了理论模型，最后总结了一套光栅槽面的非线性变形抑制方法，也提出了主副双刀预成形机械刻划方法和激光原位辅助的新型机械刻划工艺方法。为寻求从理论角度调控机械刻划工艺参数进而提高机械刻划槽形质量提供依据，也为新型机械刻划工艺方法的提出和实现奠定了基础。