Optics and Precision Engineering, Volume. 26, Issue 7, 1719(2018)
Study on sensitivity of surface deviation for aspheric mirror blank on centrifugal melting casting
Centrifugal melting casting technology has unique advantages in the manufacture of large aspheric mirror blanks. In this paper, the centrifugal casting process and the quality of the mold embryo were studied in depth by using a self-developed shrinkage model experiment machine. In order to obtain the required mirror blank, the processes of preparing the coating, heating, cooling and preserving the heat of the mold were introduced in detail. The influencing factors of shape deviation in the mirror blank production were studied by comparing simulation values with experimental results. The influence of the coefficient of thermal expansion, cooling rate, diameter, and heating temperature on the surface deviation was analyzed, and a mathematical expression relating these parameters to the deviation was derived. The compensation of the deviation was then calculated in two iterations, thus reducing the surface deviation from 84 to 33 μm. The compensation results met the design requirements. Using centrifugal casting technology, the aspheric mirror embryo can be prepared to meet the vertical deviation specifications of its upper surface in the range of 30~40 μm.
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ZHANG Xin-ming, XU Xin-li, CAI Peng, YU Yang, ZHAO Li-Xin. Study on sensitivity of surface deviation for aspheric mirror blank on centrifugal melting casting[J]. Optics and Precision Engineering, 2018, 26(7): 1719
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Received: Nov. 1, 2017
Accepted: --
Published Online: Oct. 2, 2018
The Author Email: Xin-ming ZHANG (zxm@cust.edu.cn)