Influence Of Curing And Sintering Parameters On Molding Quality Of Heterogeneous Functional Parts Fabricated By 3D Printing

Heterogeneous functional parts refer to parts made of different materials with specific functions.Traditional electromechanic separation manufacturing methods have the disadvantages of complex process,low precision,poor performance,and poor manufacturing flexibility.Integrated injection molding technology combined with appropriate curing process can achieve simultaneous injecting and curing of supporting and protective structure and functional system,which is not only easy to realize the formation of complex structures,but also simplifing the manufacturing process.However,there are many types of curing processes,of which the mechanisms are complex.The curing process parameters directly affect the performance of the final formed parts.In this paper,the effects of process parameters of UV curing and flash sintering on the performance of molded parts and parameter optimization are studied,aiming to improve the elastic modulus of UV resin and the conductivity of conductive patterns.(1)In order to solve the problem of low elastic modulus of the cured parts caused by the layer-by-layer UV curing method,the orthogonal test is designed to analyze the key factors affecting the elastic modulus;Using the analysis method of reaction kinetics,the relationship between the elastic modulus and the incident light intensity is derived,and based on this,the experimental data is fitted to establish a prediction model of the elastic modulus with a prediction accuracy of 96%;On this basis,the elastic modulus is increased by 31%by increasing the curing interval and using the UV post-curing process.(2)For the problem of unstable flash sintering quality,on the basis of the heat conduction equation,a control equation describing mass transfer is added,and the equivalent heat capacity is used to describe the phase transition of the substance,and a finite element model describing the temperature change in the flash sintering process is established.Through simulation and experiment,the temperature and conductivity of the conductive pattern under different sintering parameters are analyzed.(3)A sintering energy optimization method based on the Kriging proxy model is proposed.The optimization goal is to minimize the temperature difference between the highest temperature of the conductive pattern and the ideal temperature.The initial sample points are uniformly selected to establish a proxy model.Based on the maximization expectation improvement criterion,the accuracy of the agent model is improved and the optimal solution is gradually approached.The results show that the conductivity increases by 28%after optimization.(4)An integrated forming experiment platform for heterogeneous functional parts is been developed and tested to realize the inkjet printing of UV ink and nano silver conductive ink,combined curing of UV curing and flash sintering,and controlling functions of curing and sintering energy.Finally,the experimental platform is used to fabricate a microstrip antenna with a center frequency of 6 GHz,a conductivity of 3.9×107S/m,an adhesion force of ISO standard level 1,and the substrate elastic modulus of 1.6Gpa.In this paper,through theoretical research and experimental analysis of the UV curing process and flash sintering,a parameter optimization method is proposed to improve the elastic modulus of the UV resin and the conductivity of the conductive pattern,which is helpful for the theoretical research and process optimization of the integrated forming of heterogeneous functional parts,such as conformal load-bearing antennas.