The Research On The Evolution Of The Surface Profile Of Planar Components In The Lapping Process

Ultra-precision planar components are widely used in weapons targeting systems,astronomical telescopes,optical imaging,and various optomechanical products,etc.The demand is huge and the need for automated batch processing is constantly prominent.The surface accuracy and surface quality of planar optical components are decisive factors for their performance.However,in the actual processing process,there is a long component processing cycle and repeated changes in the convergence procedure of surface profile error,making it difficult to achieve accurate control of the processing process.Lapping,which brings workpieces closer to their target surface profile and target dimensional accuracy,is the dominant process applied to the machining of planar components.However,lapping,a centuries-old traditional process,still relies on the experience of workers,which hinders the stable and efficient production of ultra-precision planar components in batch.In order to improve the automation of the lapping process and the stability of the machining quality,a surface profile evolution model for the lapping process is proposed to predict the surface profile evolution process of the workpiece and the lapping plate during the lapping process,providing a theoretical basis for the automation and efficient processing of the lapping process.The main research work is as follows.(1)The lapping process removal mechanism was investigated.By measuring the material removal rate distribution of the workpiece and the lapping plate,the evolution of the surface profile of the workpiece and the lapping plate was initially investigated.The influence of twobody wear and three-body wear on the distribution of the Preston coefficient during the lapping process was analyzed,and the influence of the distribution of abrasive particles and workpiece debris in two-body wear on the distribution of the material removal rate was revealed.(2)A surface profile evolution modeling method is established and a MATLAB program is written to calculate the tilt angle of the workpiece during the lapping process by solving the balance equations of resultant force and moment,so that the contact pressure distribution between the workpiece and the lapping plate can be calculated more accurately.A combined experimental and simulation method for the calibration of the Preston coefficient is proposed,which,in combination with the surface profile evolution model,can predict the surface profile evolution of the workpiece and the lapping plate during the lapping process.(3)Following the research objective of investigating the evolution of the surface profile in the lapping process,a dedicated experimental device was constructed.Using the test measurement device,the stability of the friction force during the lapping process was monitored in real-time to reflect the stability of the Preston coefficient through the processing of K9 planar optical glass.The experimental device can measure the surface profile of the lapping plate at fixed intervals,in combination with the surface profile of the workpiece measured by the planimetry,can be compared with the surface profile evolution of the workpiece and the lapping plate predicted by the surface profile evolution modeling method to verify the accuracy of the surface profile evolution modeling method.(4)The surface profile evolution modeling method was applied in a MATLAB program to predict the surface profile evolution of workpieces and lapping plate,and the surface profile prediction results were verified by a lapping experiment on a planar optical glass(?100 mm)with a composite copper lapping plate.The experimental results show that the proposed method can predict the surface profile evolution of the workpiece and the lapping plate with high accuracy.As a result,the dressing time to the lapping plate can be accurately predicted,successfully reducing the PV value of the workpiece(with 5 mm edge exclusion)from 5.279?m to 0.267 ?m in 30 minutes.