Development Of Optical Glass Precision Molding Equipment Molds

The optical glass precision hot press forming technique is a fast and efficient processing of new optical components molding process.In that process,first put the glass blank which have been preformed in the lower mold,while the mold and glass blanks are heated to the appropriate temperature range near the temperature of the conversion point,in the anaerobic environment,copy the shape of the face of the mold core to glass blank by folding the upper and lower molds,and then through the access to nitrogen to adjust the cooling rate of different temperature range until cooled to room temperature,directly to the available optical glass lens.This technology features is omitted conventional grinding,polishing and other processes,direct processing of optical components,especially aspheric,microlens arrays and diffractive optics,etc.,with high efficiency,suitable for mass production and environmental protection,etc.,is the market more mainstream optical glass lens production methods in today.The goal of this paper is to develop a set of optics for optical glass precision hot press molding equipment,the required processing of the mold surface accuracy error of less than 5?m,surface roughness less than 10 nm.In the research,firstly,all kinds of mold structure,molding process and mold material characteristics are fully researched and analyzed,and then on this basis to preliminary design of optical molds.By comparing the material properties of die steel,WC and SiC,it is determined that WC is used as mold material.Then,compared with the working characteristics of stamping dies,injection molds and die casting molds,it is determined that the structure of the optical die in this paper is based on the positioning of the guide pin and the mold in the mold base.On this basis,the ABAQUS software is used to simulate the designed mold to verify its deformation near the temperature of the glass softening point,analysis of its stress and strain can not meet the molding requirements,it is found that the stress strain of WC mold is much better than that of H13 mold at molding temperature.And then build a finite model by selecting the viscoelastic model,setting the boundary conditions.Simulate the heating,molding,annealing and cooling process using the model and changes in stress and strain are observed.The simulation results show that the larger part of the stress mainly occurs at the inflection point of the glass preform and the mold cavity,the residual stress of the lens center of the bottom is almost zero,after the annealing of the glass lens,the stress release is lower than that of the non-annealed.The influence of the molding parameters on the glass stress was simulated,it shows that in pressing stage,as the temperature increases,the maximum stress decreases.As the rate increases,the maximum stress increases.In annealing and cooling state,the residual stress increases as the pressure and annealing rate increases,but the annealing rate has a greater effect on the residual stress.According to the simulation results,a set of the most suitable process parameters is proposed.Finally,after the mold is machined and assembled on the equipment,improving the design of the mold through the molded glass lens experiment.