Research On The Ultrasonic Polishing Process With Variable Pressure For Optical Glass Curved Surface

Optical glass is widely used in optical instruments,biomedicine,aerospace and other fields because of its excellent mechanical properties.The surface quality of optical glass after processing plays a decisive role in its application.The optical glass itself has the defects of high brittleness and low fracture toughness.The possibility of cracks caused by brittle fracture in the process of processing is high,which seriously affects the service life of optical glass.As the last process of optical glass processing,polishing plays a decisive role in the surface quality of the processed optical glass.Ultrasonic vibration assisted polishing technology changes and optimizes the kinematics characteristics of polishing tools in the original processing process of optical glass,and has great potential in improving the surface quality parameters of the workpiece.At present,most of the researchers in the field of ultrasonic vibration polishing technology mainly focus on plane glass,but little research on polishing technology of smooth curved surface glass.The main research direction of this paper is aimed at the polishing process innovation and polishing equipment design of smooth curved surface glass.High frequency vibration is added in the polishing process,which changes the traditional polishing technology.Therefore,the traditional polishing machine can not meet the requirements of this project.Therefore,based on the traditional polishing machine,this paper optimizes and innovates on the basis of the traditional polishing machine to achieve a smooth surface The main contents of this paper are as followsFirstly,the tool head motion model,brittle material removal model and polishing pressure model of variable pressure ultrasonic polishing are established;the brittle plastic transition of BK7 optical glass is analyzed,and the critical depth of brittle plastic transition of BK7 optical glass is obtained,and the deformation area range of BK7 optical glass is obtained,and the removal model of brittle material is obtained,and the process parameters affecting polishing quality are obtained,They are polishing force,polishing tool head speed,polishing time,abrasive strength and ultrasonic amplitude.Secondly,LS-DYNA finite element analysis software is used to simulate the material removal process.According to the actual polishing conditions,the simulation model under the action of a single abrasive particle is established,and the influence of the depth of the abrasive particle and the movement speed of the abrasive particle on the polishing effect is simulated and analyzed.Then,select the motion mode suitable for optical surface polishing,analyze the main components of the five axis linkage polishing platform,realize the variable pressure control in the optical curved surface glass polishing by using the high-speed on-off valve,establish the pressure loading model,carry out the size modeling analysis of each part of the machine tool in the three-dimensional software,and then assemble the whole machine tool according to the assembly Figure in the actual process of building the polishing machine,at the same time designed the polishing fluid atomization device.Finally,the process parameters are optimized by using the five axis linkage polishing machine.The influence proportion of the five polishing parameters on the experimental results is obtained by orthogonal experiment,and the influence law of different polishing parameters on the surface quality of the workpiece after polishing is obtained.