DEVELOPMENT OF ULTRA-PRECISION MACHINING SYSTEM FOR ASPHERIC MIRROR BASED ON ARC ENVELOPE GRINDING METHOD

该项目涉及基于一种称为“弧包络磨削法（AEGM）”的新型磨削技术的超精密磨削系统的开发。AEGM用于磨削非球面陶瓷反射镜，提高了砂轮寿命和磨削性能，并显著降低了总生产成本。设计并搭建了利用AEGM的新型仪器所需的仪表和控制系统。在超级计算机上计算刀具轨迹，并在与该超级计算机相连的PC机上进行数控程序生成和刀具轨迹补偿。其次，研究了圆弧加工精度、砂轮设计、磨削工件的表面粗糙度和形状精度。我们开发了一种精密的修整和修整装置，称为“圆弧修整器”。整型机用于圆截面轮廓的机上整型。对圆弧整型机的整型精度进行了测试，结果表明，圆弧整型机的轮廓和半径误差分别在0.5 mm和0.08mm以内。此外，为了获得更好的形状精度，我们研究了一种分辨率小于10 nm的机器形状测量仪器。接下来，我们用真轮进行了AEGM磨削试验。利用该磨削系统，成功磨削了直径为100mm的玻璃和碳化硅非球面反射镜。第一次磨削（不加补偿）后的形状误差小于1.8 μ m，粗糙度R<@D2max@>D2=82nm （R<@D2a@>D2=10nm）。研制的系统具有良好的非球面陶瓷镜面磨削性能。该系统不仅适用于制造用于外太空的大尺寸光学元件，也适用于制造用于微型器件的微尺寸光学元件，在不久的将来将得到广泛应用。

This project deals with the development of an ultra-precise grinding system based on a new grinding technique called the "Arc Envelope Grinding Method (AEGM)". AEGM,which is used for grinding aspheric ceramic mirrors, increases both wheel life and grinding performance, and significantly decreases total production costs. The necessary instrumentation and control system of our new instrument that utilizes AEGM have been designed and built. The tool path was calculated on a supercomputer, and the CNC program generation and tool path compensation were performed on a PC linked to the same supercomputer. Next, arc truing accuracy, wheel design, surface roughness and form accuracy of the ground workpiece were investigated.We developed a precision truing and dressing device, called an "Arc Truer". The truer is for an on-machine truing of a round cross-sectional profile. An examination of truing accuracy of the Arc Truer revealed that profile and radius errors were within (]SY.+-。[)0.5 mum and (]SY.+-。[)0.08mm, respectively. To obtain better form accuracy, furthermore, we investigated an on-machine form-measuring instrument with resolution of less than 10 nm. Next, we tried the AEGM grinding tests with the trued wheel. Using this grinding system, aspheric mirrors of glass and silicon carbide, 100 mm in diameter, were successfully ground. The form error after the first grinding (without any compensation) was less than 1.8 mum, and the roughness was R<@D2max@>D2=82nm (R<@D2a@>D2=10nm). The AEGM-based system which we developed demonstrated excellent grinding performance of aspheric ceramic mirrors. This system is applicable for manufacturing not only large-scale optics for outer-space applications, but also micro-size optics for micro devices, which will be widely used in the near future.