五轴加工中心范成铣磨离轴非球面研究

离轴非球面作为非球面的一部分,是空间光学系统、天文学和高精度测量系统不可或缺的光学器件。针对空间光学对离轴非球面光学元件制造技术的重大需求,开展了离轴非球面反射镜的精密铣磨加工技术研究。分析了五轴联动范成法铣磨离轴非球面的原理,将离轴非球面所在的同轴母镜离散为一系列不同半径的球面环带,将工件坐标系建立在待加工离轴非球面的同轴母镜中心位置,使用杯形砂轮依次范成离轴镜所在的同轴母镜上的环带,由众多的球面环带拼接出离轴非球面。对Φ100mm直径离轴抛物镜进行工艺试验,环带宽度7.28mm,一次加工面形精度PV达到7μm,RMS达0.622μm,加工用时7min。研究表明该方法具有可行性,为离轴非球面快速铣磨提供了有效的解决方案。

Study on generating method for off-axis aspherical mirror grinding based on five-axis machining center

As a kind of aspherical surface,off-axis aspherical surface is an indispensable optical device for space optical systems,astronomy and high-precision measurement system.In response to the significant demand of manufacturing technology of large-scale off-axis aspheric optical components in space optics,researches on precision grinding technology of off-axis aspheric mirrors have been carried out.The principle of grinding off-axis aspheric surface using generating method in a five-axis machine tool is analyzed.The coaxial parent mirror where the off-axis aspheric surface locates is divided into a series of spherical rings with different radii,and the workpiece coordinate system is established at the center of the coaxial parent mirror of the off-axis aspheric surface to be machined.The cup wheel grinds each ring on the coaxial parent mirror in turn,and the off-axis aspheric surface is formed by splicing some of the rings.Based on this method,an off-axis parabolic mirror with the aperture of 100 mm is sucessfully machined.The width of the divided rings is set to 7.28 mm.After one process which takes only 7 min,the PV value of the surface error reaches 7μm,and the RMS value of the surface error reaches 0.622μm.The experiment proves the feasibility of this method and provides an effective solution for off-axis aspheric rapid grinding.