On-line Electrical Discharge Dressing And Detection Of Arc-shaped Metal Bonded Diamond Wheels

With the rapid development of space optics application technology such as earth observation, deep space instrumentation and the airborne laser(ABL), the manufacture of large-aperture aspheric mirror has become the focus of the space optical components. Due to the high hardness of the Si C ceramics, the wear of the arc-shaped metal bonded diamond wheels is very serious in the grinding of large-aperture aspheric Si C mirror. The Surface accuracy and surface/sub-surface quality of the aspheric mirror will be affected seriously if the grinding wheel is not timely dressed and compensated.Therefore, this paper focus on the on-line dressing and detection of the arc-shaped metal bonded diamond wheels. The application features of arc-shaped grinding wheels and the influence of profile error of the grinding wheel on the surface accuracy of the mirror are studied firstly. The rotating cup-shaped electrode discharge dressing device of the grinding wheel is developed based on the analysis and the experiments are carried out with the device. The online detection system is built up with the eddy current sensor. The realization of the in-process dressing and detection of the arc-shaped grinding wheel is important for the improvement of the grinding quality of the aspheric mirror.The application features of the arc-shaped wheels in the grinding of the aspheric mirror are analyzed and a new scheme of asymmetric profile arc-shaped wheel is proposed to increase the utilization of the grinding wheel. The theoretical analysis of the size selection of the wheel is made. The influence of the profile error of the arc on the surface accuracy of the aspheric mirror after grinding is analyzed. A theoretical formula of the aspheric surface error in each point is established. The research provides the basis for determining the dressing method and evaluation of evaluation of the wheel profile error.A rotating cup-shaped electrode online electro discharge dressing device for the arcshaped wheels is developed. The error source of the dressing device and its influence on the arc profile error of the wheel are analyzed. The experiments are carried out to study the influence of the discharge parameters on the dressing precision, efficiency and surface topography of the wheel after dressing with the dressing device. The experimental results show that the online dressing device can did the dressing for the symmetrical and asymmetrical profile arc-shaped wheel.The output characteristics of the eddy current displacement sensor measuring the metal object is studied. The data acquisition program is written with the software of Lab View. Finally, the online detection system based on the eddy current displacement sensor is established. The detection experiments for the metal bonded diamond grinding wheel are carried out. The results show that the detection system is able to realize the measurement of rotary errors and arc-shaped profile.