Separate characteristic of the tangential ultrasonic vibration assisted grinding (TUAG) machining is analyzed based on TUAG process, and a critical speed formula is given to correctly set the machining parameters to i...Separate characteristic of the tangential ultrasonic vibration assisted grinding (TUAG) machining is analyzed based on TUAG process, and a critical speed formula is given to correctly set the machining parameters to insure the separate characteristics of TUAG process. The critical speed is not only related to the ultrasonic vibration amplitude and frequency, but also to the grinding wheel velocity and the cutting point space, and the grinding force can be decreased during the TUAG process with separability. Grinding force experiments are conducted, and the experimental results are in good agreement with the theoretical results.展开更多
The theoretical model of axial ultrasonic vibration grinding force is built on the basis of a mathematical model of cutting deforming force deduced from the assumptions of thickness of the undeformed debris under Rayl...The theoretical model of axial ultrasonic vibration grinding force is built on the basis of a mathematical model of cutting deforming force deduced from the assumptions of thickness of the undeformed debris under Rayleigh distribution and a mathematical model of friction based on the theoretical analysis of relative sliding velocity of abrasive and workpiece. Then, the coefficients of the ultrasonic vibration grinding force model are calculated through analysis of nonlinear regression of the theoretical model by using MATLAB, and the law of influence of grinding depth, workpiece speed, frequency and amplitude of the mill on the grinding force is summarized after applying the model to analyze the ultrasonic grinding force. The result of the above-mentioned law shows that the grinding force decreases as frequency and amplitude increase, while increases as grinding depth and workpiece speed increase; the maximum relative error of prediction and experimental values of the normal grinding force is 11.47% and its average relative error is 5.41%; the maximum relative error of the tangential grinding force is 10.14% and its average relative error is 4.29%. The result of employing regression equation to predict ultrasonic grinding force approximates to the experimental data, therefore the accuracy and reliability of the model is verified.展开更多
离轴非球面反射镜是高分辨率、大视场空间相机的核心元件,其镜面的形状精度和表面质量要求极高,加工难度很大,一直是光学系统先进制造技术的瓶颈。针对国家对空间大型SiC光学元件制造技术的重大需求,开展以大口径、高陡度、大离轴量和...离轴非球面反射镜是高分辨率、大视场空间相机的核心元件,其镜面的形状精度和表面质量要求极高,加工难度很大,一直是光学系统先进制造技术的瓶颈。针对国家对空间大型SiC光学元件制造技术的重大需求,开展以大口径、高陡度、大离轴量和大偏离量为特点的离轴非球面反射镜的精密铣磨加工技术研究。开发非球面反射镜计算机辅助数控编程技术,提出五轴联动斜轴定角度加工方式,建立旋转中心在镜面外的螺旋加工轨迹,避免镜面几何中心处的加工残留。并基于五轴加工中心(型号DMG Ultrasonic 100-5)搭建超声振动辅助铣磨加工平台,以900 mm×660 mm口径离轴非球面SiC反射镜镜坯为加工样件进行工艺试验,加工面形精度峰谷值(Peak to valley,PV)达到18.8μm,方均根值(Root mean square,RMS)达到3.5μm。研究为按照非球面方程高精度铣磨超大尺度精度比离轴非球面反射镜提供了有效的解决方案。展开更多
基金supported by the National Natural Science Foundation of China (Grant No.50575127)
文摘Separate characteristic of the tangential ultrasonic vibration assisted grinding (TUAG) machining is analyzed based on TUAG process, and a critical speed formula is given to correctly set the machining parameters to insure the separate characteristics of TUAG process. The critical speed is not only related to the ultrasonic vibration amplitude and frequency, but also to the grinding wheel velocity and the cutting point space, and the grinding force can be decreased during the TUAG process with separability. Grinding force experiments are conducted, and the experimental results are in good agreement with the theoretical results.
基金Project(51275530)supported by the National Natural Science Foundation of China
文摘The theoretical model of axial ultrasonic vibration grinding force is built on the basis of a mathematical model of cutting deforming force deduced from the assumptions of thickness of the undeformed debris under Rayleigh distribution and a mathematical model of friction based on the theoretical analysis of relative sliding velocity of abrasive and workpiece. Then, the coefficients of the ultrasonic vibration grinding force model are calculated through analysis of nonlinear regression of the theoretical model by using MATLAB, and the law of influence of grinding depth, workpiece speed, frequency and amplitude of the mill on the grinding force is summarized after applying the model to analyze the ultrasonic grinding force. The result of the above-mentioned law shows that the grinding force decreases as frequency and amplitude increase, while increases as grinding depth and workpiece speed increase; the maximum relative error of prediction and experimental values of the normal grinding force is 11.47% and its average relative error is 5.41%; the maximum relative error of the tangential grinding force is 10.14% and its average relative error is 4.29%. The result of employing regression equation to predict ultrasonic grinding force approximates to the experimental data, therefore the accuracy and reliability of the model is verified.
文摘离轴非球面反射镜是高分辨率、大视场空间相机的核心元件,其镜面的形状精度和表面质量要求极高,加工难度很大,一直是光学系统先进制造技术的瓶颈。针对国家对空间大型SiC光学元件制造技术的重大需求,开展以大口径、高陡度、大离轴量和大偏离量为特点的离轴非球面反射镜的精密铣磨加工技术研究。开发非球面反射镜计算机辅助数控编程技术,提出五轴联动斜轴定角度加工方式,建立旋转中心在镜面外的螺旋加工轨迹,避免镜面几何中心处的加工残留。并基于五轴加工中心(型号DMG Ultrasonic 100-5)搭建超声振动辅助铣磨加工平台,以900 mm×660 mm口径离轴非球面SiC反射镜镜坯为加工样件进行工艺试验,加工面形精度峰谷值(Peak to valley,PV)达到18.8μm,方均根值(Root mean square,RMS)达到3.5μm。研究为按照非球面方程高精度铣磨超大尺度精度比离轴非球面反射镜提供了有效的解决方案。
