Research On Precision Molding Process Of 3D Curved Glass Cover Plate Of Mobile Phone

In recent years,3D curved glass has been widely used in smartphones for its ergonomic curved edges that provide an excellent touch feel and novel appearance.Precision molding technology has the advantages of high efficiency and low cost,which can realize the mass production of mobile phone 3D curved glass cover plate.However,in the process of molding,unreasonable process parameters often lead to large shape deviation of 3D curved glass cover plate,and even lead to fracture due to excessive internal stress.Therefore,in this paper,the effects of relevant process parameters on the molding performance of 3D curved glass are investigated by means of finite element simulation combined with experimental verification,which provide a reference for the reasonable setting of process parameters in actual production.The main contents include the following aspects:(1)For the heating stage,different heating curves are input for simulation,and the optimal heating curve is selected with the residual stress in the glass at the end of the heating stage as the index.For the molding stage,the control variable method is used to simulate,with the molding temperature,mold pressure,loading time and mold speed as variables.Compare and analyze the internal stress and shape deviation of the glass after the end of molding,and get the trend of the influence of each process parameter on the molding quality of 3D curved glass.(2)Multi-factor orthogonal simulations are designed for constant pressure molding and constant speed molding respectively.Taking the maximum internal stress and shape deviation of glass as the evaluation indexes,the influence of each factor on the forming quality and the optimal process parameters are obtained by range analysis and inter-subject effect tests.The optimal process parameters for constant pressure molding are as follows: the molding temperature is 590℃,the mold pressure is 1600 N and the loading time is 1s.The optimal process parameters for constant speed molding are as follows: the molding temperature is 590 ℃,the pressing speed is 0.1 mm/s.(3)Orthogonal experiments are designed to verify the orthogonal simulation results of constant pressure molding.Taking the glass breaking probability and shape deviation as the evaluation indexes,the optimal process parameters are obtained by range analysis as follows: the molding temperature is 590℃,the mold pressure is1600 N,and the loading time is 1s.The experimental results are consistent with the simulation.(4)The spring-back phenomenon of glass at the end of annealing stage is simulated and analyzed.Taking the spring-back and internal stress on the curved surface of the glass at the end of annealing as the evaluation indexes.Using the control variable method,the simulation is carried out with the annealing end temperature and annealing duration as variables,and the optimal annealing process parameters are derived as follows: the annealing temperature is 400℃ and the annealing duration is1020 s.Based on the spring-back curve,the mold cavity curve is pre-compensated.After pre-compensation,the plane and curved spring-back parameters of glass are reduced to 22.8% and 8.5% respectively.Pre-compensation can effectively reduce the shape deviation caused by spring-back.