The demand for large aperture lenses with high surface quality and form accuracy used for single-lens reflex cameras has been increasing. Generally, large aperture glass lenses are produced by ultra-precision grinding. Considering the increasing global competition, the grinding process has to be improved. However, highly efficient grinding causes worse surface quality, which leads to much polishing and ultimately results in lower form accuracy. Thus in this study, aiming at the realization of highly efficient and precise grinding of glass lenses, cross grinding of optical glass BK7 is carried out. As a first step of the study, the influence of grinding conditions on the surface quality is investigated experimentally.
This study presents the development of an ultra-precision grinding system based on a
new grinding technique called the “In-Process Grinding Method (IPGM)”. IPGM which is used for
grinding aspheric lens increases both the production and grinding performance, and significantly
decreases total production costs. To enhance the precision grinding productivity of ultra-precision
aspheric lens, we present here an ultra-precision grinding system and process for the aspheric
micro-lens. The tool path was calculated and CNC program generation and tool path compensation
were performed for aspheric lens. Using this ultra-precision grinding system, aspheric lens, 4mm in
diameter, were successfully performed. The profile error after the first grinding without any
compensation was less than 0.6μm, and surface roughness Ra was 0.01μm. In-process grinding was
performed with compensation. Results of the profile accuracy P-V 0.3μm and surface roughness Ra
0.006 μm were obtained.
CVD diamond has become the mainstream trend for the development of diamond. Its ultra precision machining is one of the key technologies for expanding the application of CVD diamond film. The efficient polishing method is studied, called accelerant polishing technology, which can lower the activation energy needed in diamond graphitization by the accelerant action of transition metal. It accelerates reaction rates of graphitization and promotes the implementation of diamond’s removal mechanism. Experimentation results indicate that the polishing method is one new type of precision polishing technology with low cost and high efficiency.
Ultra-precision machining technology is adapt to the development of modern technology a new technology of mechanical processing, the new achievement of the development of the integrated application of the mechanical technology and modern electronic technology, measurement technology and computer technology in advanced control, testing method, etc., makes a further improve the precision of machining. At present the increasing maturity of the ultra precision machining, has formed a series, it include ultra precision cutting, super precision grinding and super precision grinding and super precision special processing, etc. Ultra-precision machining to high precision, high efficiency, large-scale, miniaturization, intelligent, process integration, the integration of online processing detection, such as green direction.
Large aperture lenses with high surface quality are demanded for professional imaging products such as single-lens reflex cameras and astronomical telescopes. Large aperture optical lenses are shaped by ultra-precision grinding and finished by prolonged polishing. However, the prolonged polishing process leads to deterioration of the form accuracy. In order to reduce the amount of polishing, ductile-mode ultra-precision grinding is demanded. In this study, a rubber bonded wheel, which has a low elastic modulus, is used for grinding of spherical glass BK7, and influence of the hardness of the rubber bonded wheel and abrasive chip thickness on brittle fracture and surface roughness are experimentally investigated.
Ultra precision grinding is currently the main technology for large scale advanced optical lens machining. In this paper, the machining system of ultra precision surface grinder is investigated. The experiments of new wedged aspheric lens with the dimension of 430*430mm have been conducted by SD600 diamond wheel, and the parallel grinding, cup truing and on-machine measuring are used for good accuracy. The results show the effective machining system and the problem for next research.
This paper puts forward an intelligent single-plane biaxial balance monitor system, which is used in ultra-precision grinding. It adopts the method of single-plane balance correction for the vibration of wheel and workpiece. And this system can also be used for integral balance. For ultra-precision grinding, caused by the mutual influence of the vibration of wheel and workpiece, there will be a ripple on the workpiece surface, which is mainly influenced by the frequency ratio of wheel to workpiece, the feed rate and the vibration of wheel and workpiece. This system can improve the machining accuracy, reduce the surface error of workpiece and appraise the integrated machining result, by analyzing the vibration data of wheel and workpiece and adjusting machining parameters.
The FEM Simulation of Ultra-precision Grinding of Optical Glass with Micro-structured Coarse-Grained Diamond Wheels