光学非球面超精密磨削的微振动对成形精度影响研究

Study on Influence of Micro-vibration During the Optical Aspheric Surface Ultra-precision Grinding on Forming Accuracy

轴对称非球面光学元件超精密磨削加工过程中砂轮的不平衡量和机床主轴引起的微振动直接影响工件成形精度及粗糙度。通过分析磨削过程中产生的微振动现象,建立了砂轮轴和磨床主轴微振动引起的非球面球面半径偏差的数学模型,研制了高精度微振动动态测量装置,测量精度达0.02μm.针对研制的大口径超精密非球面磨削机床分析测量了砂轮轴转速和磨床主轴转速、砂轮轴和磨床主轴的静压轴承油压对砂轮轴和磨床主轴的径向微振动和轴向微振动的影响,确定了使该磨床砂轮轴和磨床主轴微振动量最小时的砂轮轴转速和静压轴承油压以及磨床主轴转速和静压轴承油压的工艺参数,利用该参数加工的500 mm口径的非球面面型精度小于4μm.

In ultra-precision grinding process of the axial symmetric aspheric optical element,both imbalance of grinding wheel and micro-vibration of spindle would directly affect the forming accuracy and roughness.Analyzed the phenomenon of micro-vibration in grinding,a mathematical model of the aspheric surface＇s spherical radius deviation caused by the micro-vibration was established,and a dynamic high-precision micro-vibration measurement device with accuracy of 0.02 μm was developed.For the developed large-diameter ultra-precision aspheric grinding machine,the influence of the rotation speed of grinding wheel and spindle and the oil pressure of hydrostatic bearing on the radial and axial micro-vibration of grinding wheel and spindle was measured and analyzed.The parameters of the rotation speed of grinding wheel and the oil pressure of hydrostatic bearing and the rotation speed of spindle were determined to make the micro-vibrations of grinding wheel and spindle minimum.The machining results show that the error of aspheric surface of 500 mm in diameter can be less than 4 μm.