Study On Process Optimization Of Ultra-Precision Grinding Technology For Aspheric Glass Mold Core

Glass molding is the main technology for mass production of high-quality aspheric optics.In glass molding technology,the ultra precision machining of die core plays an important role in the performance and quality of glass molding lenses.Tungsten carbide alloy,as an ideal core material for glass die pressing,has the advantages of high hardness,high wear resistance,high chemical stability and long service life.Ultra-precision grinding technology is the most commonly used method for machining tungsten carbide alloy.By using this technology,glass mold core with good surface quality can be obtained.With the rapid development of the field of optical engineering,the requirements for the surface quality of the molded lens and mold core are becoming more and more strict.Therefore,further reducing the surface roughness of tungsten carbide die core has important research significance and scientific research value.To control the surface roughness of the tungsten carbide mold core and improve the surface quality of the mold core,the optimization of ultra-precision grinding technology was carried out in this paper.Firstly,the selection principle of the grinding wheel in ultra-precision grinding is introduced.According to the material characteristics of tungsten carbide alloy,the diamond grinding wheel with resin bond was selected.The existing grinding methods of the aspherical surface were discussed.On this basis,the inclined axis single-point grinding method suitable for the concave aspherical surface was selected,and the grinding wheel path planning equation was established according to this grinding method.Secondly,the material properties of tungsten carbide alloy are introduced.The removal mechanism and brittle-plastic transformation mechanism of tungsten carbide alloy were studied and the maximum undeformed chip thickness model was established.The crack formation mechanism of grinding tungsten carbide alloy was analyzed,and the process method of suppressing crack formation was discussed.These results provide a theoretical basis for establishing a reliable process scheme.Then,Abaqus software was used to simulate the grinding process.The influences of grinding depth,feed speed,wheel speed,and workpiece speed on workpiece surface roughness were analyzed.According to the simulation results,the reasonable range of process parameters was preselected,which provided guidance for the subsequent process optimization experiment.Finally,based on the process parameters selected by simulation,Taguchi method was used to design the orthogonal grinding experiment of tungsten carbide alloy element.The influence degree of each process parameter on the surface roughness of components after grinding was discussed,the optimization of process parameters was completed,and the optimal process scheme was determined.The ultra-precision grinding of tungsten carbide alloy aspherical glass mold core with diameter of 11.8mm was completed by using the technology scheme.The aspherical core with PV precision of 0.24μm and Ra of 3.379 nm was obtained.