Ultrasonic vibration-assisted grinding(UVAG)is an effective and promising method for machining of hard-to-cut materials.This article proposed an ultrasonic vibration plate device enabling the longitudinal full-wave an...Ultrasonic vibration-assisted grinding(UVAG)is an effective and promising method for machining of hard-to-cut materials.This article proposed an ultrasonic vibration plate device enabling the longitudinal full-wave and transverse half-wave(L2T1)vibration mode for UVAG.The characteristics of two-dimensional coupled vibration in different directions were analyzed on the basis of apparent elastic method and finite element method.Furthermore,a correction factor was applied to correct the frequency error caused by the apparent elastic method.Finally,the comparative experiments between the conventional creep-feed grinding and UVAG of Inconel 718 nickel-based superalloy were carried out.The results indicate that the apparent elastic method with the correction factor is accurate for the design of plate device under the L2T1 vibration mode.Compared with the conventional creep-feed grinding,the UVAG causes the reduction of grinding force and the improvement of machined surface quality of Inconel 718 nickel-based superalloy.Furthermore,under the current experimental conditions,the optimal ultrasonic vibration amplitude is determined as 6μm,with which the minimum surface roughness is achieved.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financially supported by the National Natural Science Foundation of China(Nos.51921003 and 51775275)National Key Laboratory of Science and Technology on Helicopter Transmission(Nanjing University of Aeronautics and Astronautics)(No.HTL-A-20G01)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX20_0179)。
文摘Ultrasonic vibration-assisted grinding(UVAG)is an effective and promising method for machining of hard-to-cut materials.This article proposed an ultrasonic vibration plate device enabling the longitudinal full-wave and transverse half-wave(L2T1)vibration mode for UVAG.The characteristics of two-dimensional coupled vibration in different directions were analyzed on the basis of apparent elastic method and finite element method.Furthermore,a correction factor was applied to correct the frequency error caused by the apparent elastic method.Finally,the comparative experiments between the conventional creep-feed grinding and UVAG of Inconel 718 nickel-based superalloy were carried out.The results indicate that the apparent elastic method with the correction factor is accurate for the design of plate device under the L2T1 vibration mode.Compared with the conventional creep-feed grinding,the UVAG causes the reduction of grinding force and the improvement of machined surface quality of Inconel 718 nickel-based superalloy.Furthermore,under the current experimental conditions,the optimal ultrasonic vibration amplitude is determined as 6μm,with which the minimum surface roughness is achieved.
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。
