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测量并分析了碳化硅反射镜坯体光学加工的残余应力。采用X射线衍射法测定了磨削成形、研磨以及抛光过程引入的表面残余应力的性质和大小;采用逐层抛光法测定了在用120#粒度金刚石砂轮磨削时引入的残余应力层厚度。研究结果表明:在用120#金刚石砂轮磨削加工时沿磨削方向和垂直于磨削方向分别引入了残余拉应力和残余压应力,其大小分别为40MPa和70MPa,应力层深度约为60μm,大于裂纹层深度;在用W7金刚石微粉研磨时引入了残余压应力,在其作用范围内残余应力平均值为60~80MPa;在抛光时理论上会引入残余压应力。在此基础上提出了在碳化硅反射镜坯体的光学加工过程中,可以通过研磨消除磨削引入的裂纹层和残余应力层。
The residual stress of the optical machining of the silicon carbide reflector body was measured and analyzed. X-ray diffraction method was used to determine the nature and size of surface residual stress introduced by grinding, grinding and polishing. The thickness of residual stress layer introduced by grinding with 120 # diamond grinding wheel was measured by layer-by-layer polishing. The results show that the residual tensile stress and residual compressive stress are respectively introduced along the grinding direction and perpendicular to the grinding direction when grinding with 120 # diamond grinding wheel, the sizes are 40MPa and 70MPa respectively, the depth of stress layer is about 60μm, Greater than the depth of the crack layer; the residual compressive stress is introduced when grinding with the W7 diamond micropowder, the average residual stress in the range of its effect is 60 ~ 80MPa; in theory, the residual compressive stress will be introduced. Based on this, it is proposed that the crack layer and the residual stress layer introduced by grinding can be eliminated during the optical processing of the silicon carbide reflector body.