双焦点反射镜离心熔铸成型过程中的反射面交界位置补偿方法

针对双焦点反射镜镜胚离心成型反射面交界位置半径偏差补偿问题，开展双焦点反射镜离心熔铸成型过程中熔体的运动趋势和反射面交界位置的偏移研究。进行离心成型过程仿真，补偿计算内外圈反射面交界位置半径偏差，并进行类比实验验证。对比双焦点反射镜成型过程的仿真和成型实验结果可知，反射面最大面形偏差分别为6.5 μm和7.2 μm，内外圈反射面交界位置半径偏差分别为5.2 μm和7.1 μm，证实了数值模拟方法可以预测双焦点反射镜离心成型曲面面形以及反射面交界位置半径。将圆筒形隔热壁设置为不同半径，对外圈反射面成型转速均为50 r/min，内圈反射面成型转速分别为90 r/min、100 r/min和110 r/min的3种不同双焦点反射镜成型进行仿真，设置隔热壁位置半径分别为31.08 mm、30.7 mm和30.39 mm，使反射面交界位置半径偏差由4.358 mm、4.264 mm和4.199 mm缩 小至2.15 μm、2.40 μm和5.30 μm. 偏差结果均为微米级，表明在离心熔铸成型过程中改变隔热壁位置半径能够对反射面交界位置半径进行补偿。

Compensation for Boundary Position of Mirror in Spin Casting of Bifocal Reflector

In order to study the radius deviation compensation method for the boundary position of the centrifugal shaped reflector surface of bifocal reflector，the trend of melt movement and the deviation of boundary position in the centrifugal casting of bifocal reflector are studied using simulation analysis and analogy experimental method. The spin casting forming process is simulated and analyzed, and studied by way of analogy experiment. The compensation calculation was conducted for the radius deviation of boundary between the inner and outer reflecting surfaces. The simulated results of the forming process of the bifocal reflector were compared with the results of the forming experiment. The results show that the maximum surface shape errors are 6.5 μm and 7.2 μm，and the radius deviations of boundary positions of inner and outer reflectors are 5.2 μm and 7.1 μm，which proves that the numerical simulation method can predict the trend of melt movement during the forming process of bifocal reflector. Different radii are set for cylindrical thermal insulating wall. The simulations are carried out with three different bifocal reflectors, which were formed at 50 r/min for the outer ring reflecting surface and 90 r/min, 100 r/min and 110 r/min for the inner ring reflecting surface. When the position radii of the thermal insulating wall is set 31.08 mm，30.7 mm and 30.39 mm，the boundary position radius deviations of reflector surface are reduced from 4.358 mm，4.264 mm and 4.199 mm to 2.15 μm，2.40 μm and 5.30 μm，respectively. The deviations radii are micron-sized. So it is verified that the boundary position radius of reflector surface can be compensated by changing the position radius of the thermal insulating wall during the spin casting.