大口径轻质反射镜坯的制造

Manufacturing of a big aperture lightweight mirror

给出了制造大口径轻质反射镜坯的机械法减重技术及所制造的反射镜坯。在镜坯制造过程中通过计算机辅助设计搜索轻量化加工区域的形状、大小、深度,并对其进行分类标识;编辑TPH(toolpath)轨迹数据文件,编写CNC(comput ernumbercontrol)数控系统的零件加工程序,由数控系统在图形方式下控制实际加工。同时采用化学方法消除加工过程中产生的应力与微小裂纹。加工出的大口径轻质反射镜坯达到设计要求,轻量化率达到65%以上,加工后的非球面面形精度达到0.029λ(rms,λ=633nm)。制造过程中在不同支撑状态下,变形量很小,保持了非球面面形精度稳定性,显示出了结构的稳定性。该方法已经成为大口径反射镜制造的关键支撑技术。

The mechanical light-weighting technique to manufacture a big aperture lightweight mirror was given. Based on CAD(computer aided design),the technique searches the zone of the lightweight process and marking it, then chooses the radii of the diamond tool, and describing the tool path in the lightweight process zone. If the area of the tool path covers the lightweight process zone, it will write down the tool path datum for the editing CNC program. The CNC program is made up of TPH documents and program language that follow definite regulations of frame, syntax, and format. The CNC program can control system functions such as principal axis rotating speed, tool moving speed, cooling form of mirror, workbench travel path.Meantime the chemical etching is used to eliminate the stress and minute cracks induced in the manufacturing process, which can affect the quality of the mirror and reduce its working life,and even more lead to the serious sequent of mirror breaking. Using the technique,a big aperture lightweight mirror was achieved. The results show that the big aperture lightweight mirror has met the requested specifications,with the lightweight rate of more than 65%,the precision of the aspheric surface is 0.029 λ(rms,λ=633 nm).The mirror is steady in both its testing and working status.