Study On Key Techniques Of Complex Optical Surface Precision Grinding With Damage Control

Complex optical surface has the advantages of reducing the number of optical components,simplifying the optical system,increasing design freedom and so on;it has become the new trend in the field of optical application.However,the manufacturing process of optical components with high efficiency,high quality and low cost,is the restriction for widely applications of the complex optical surface.Precision grinding is the roughing machining process of optical components,whose grinding quality determines the whole process of selected technological chain,manufacturing efficiency,manufacturing cost and other factors.In the field of optical fabrication,although the development of grinding technology has a longtime process,with the increasing of optical system performance requirements,the existing grinding technology has been unable to meet the demand for some special occasions.More complex surface shape,higher requirements for form/location precision and surface quality of optical components put forward new challenge to the existing grinding technology.The complex optical surface grinding with composite restriction of form tolerance,location tolerance and grinding damage control is the research objective,and key technologies of grinding are studied in order to achieve high efficiency,high precision and high surface quality fabrication in this paper.Research works are mainly focused on the following aspects:1.Study on form precision control technology of curved surface.According to the geometry relation during grinding process,the grinding geometric model of curved surface is established through the normal vector matching of grinding point,which can obtain exact surface grinding tool trajectory.By analyzing the relationship between the multiple error sources and machining error during grinding process,just as the relative position and orientation error between wheel and workpiece,wheel size and shape error,the error induced by tool deflection,we establish the corresponding error propagation model and propose the respective control or compensation method.Analyze the influence law of other types of errors sources and propose trajectory directly compensation method.Related researches provide effective support for form precision control in theoretical basis and technology pathway.2.Study on location precision control technology of curved surface.Severe requirements of location tolerance require that the optical measurement,evaluation and fabrication processes of curved surface are operated with corresponding reference datum.To investigate the relationship between the form error and location error and the new features during evaluation process,from the perspective of the smallest material removal volume for error correction processing,we develop least-squares local optimization method for error evaluation.Form error and location error of curved surface influence each other;with different optimal surface location matching,it will show certain regularity.Based on the wedge lens grinding,we study the error correction method of location error,which provides effective guidance for high precision location error control.3.Study on grinding damage control technology.Based on damage detection method of Magnetorheological Finishing(MRF)wedge polishing,characterization parameters(cluster depth,maximum depth,crack density,crack length)are used to quantitative study of grinding damage.By theoretical model of grinding process,analyze the relationship between grinding force and subsurface damage;point out that the force of single abrasive particle is essential factor to determine damage during the actual grinding process;the high frequency of random forces or vibration force will greatly increase the depth of local damage.Experimental studying on the grinding process indicates the lateral distribution and depth distribution law of damage,and changes law of damage depth with the grinding parameters.From the influence extent of process parameters: grain size > single cutting depth> row distance> scanning speed,which provides guidance for the optimization of process parameters.The damage growth law is studied in technological transformation process,and the results indicate that 1.6~2 times of initial damage depth is more reasonable grinding depth for removing damage.These studies provide theoretical and experimental support for making iterative grinding technological chain of removing damage under thickness constraint.4.Grinding technological process and experimental verification under multi-objective control.According to relevant studying results,propose grinding technological process under multi-objective control(form error,location error and damage);and implement the grinding test of wedge lens.The form accuracy of curved surface is greatly improved during grinding process,and the location error and the damage can be controlled within the target range,which verify the effectiveness of these researches in this paper.