Study On Medical Polycarbonate Stress Cracking And Injection Molding Process

Along with the development of the medical equipment industry,medical polycarbonate plastic injection products get more and more widely used,however in the practical application of the failure due to stress cracking problem,affecting their use.Injection molding process is actually associated with the phase transition can be compressed elastic polymer melts in complex flow passage of the non-isothermal,unsteady flow,which due to the high polymer,the viscous flow state,high elastic state and the transition of the glassy state and also experienced a complex history of engine,so the microstructure formed products and raw materials can make a big difference.The study found that the flow residual stress is mainly caused by the molecular orientation of frozen,and the greater the degree of orientation,the greater the flow of residual stress.Internal molecular chain and chain segment is random when the melt in the absence of external force.In the process of forming,when the melt was rapidly injected into the mold cavity,internal will produce a lot of shear stress;melt resulting in polymer molecular chain and chain orientation in the melt flow direction.Due to the cooling process of the melt is very fast,has the orientation of molecular chain and chain segment to achieve balance and be "frozen" inside the products,this is known as the flow of the residual stressUsing injection molding in polycarbonate raw materials for processing,this paper plans to control different molding process conditions of preparation of the performance of different PC products,through the PC sample tensile strength test,the elongation at break,bending experiments,as well as impact experiment and to analyze the influence of different stress in injection molding process for the PC products.This paper introduces a kind of to reduce the gap between process simulation and dynamics simulation of comprehensive method.On the basis of the comprehensive method,we through the back propagation(BP)neural network and the data obtained from the finite element simulation can a mapping relation between mechanical properties and process parameters of mathematical functions.Particle swarm optimization(PSO)combined with this prediction model can find the optimal process parameters,so as to significantly increase the mechanical properties of the product.Finally,optimization study on the polycarbonate(PC)made of plastic injection products implemented.Mold temperature,melt temperature,injection speed,compression,compression force,compression speed and compression waiting time is treated as design parameters.Process parameters of optimal values for PC injection products under the impact load of von Mises stress.By adopting scientific and reasonable theoretical basis for applied to this system model is established,and combined with the experimental data of injection molding process parameters optimization.Important parameters affecting the polycarbonate products are analyzed in single factor experiment,comparing the annealing process of products,aims to explore the preparation of excellent comprehensive performance and can overcome stress cracking of the injection molding process conditions,so as to provide theoretical basis for practical production.