Research On Nozzle Design And Parameters Optimization Of Microcellular Injection Molding

Due to the oil of non-renewable energy resources becomes shortage increasingly,lead toa growing trend of price of raw materials of plastic. Faced with intense competition insociety, how to reduce plastic dosage,costs and keep original performance of plastic productsbecomes crucial for company. Under this environment, microcellular injection moldingtechnology emerged,it not only reduces plastic amount, and the unique pore structure alsoimprove the overall performance of products largely.However, as a new injectiontechnique,microcellular injection technique have many problems to be solved，how toimprove the quality of products and reduce production costs is a hot research currently.In this paper, traditional injection molding machine were reformed to study the effectsof different process parameters on the microcellular products; then using intelligentalgorithm to optimize process parameters,improve the cell morphology and size stability ofmicrocellular products, the main work is as follows:(1) Equipment modificationCompared with conventional injection molding machines, special screws andsupercritical fluid system makes it expensive so as to limite its commercial application.Firstly, the traditional injection molding machine is modified, design a self-locking nozzleto control the opening and closing of the nozzle；As the key components of self-lockingnozzle—static mixer is optimized design, use polyflow software to do numerical simulationanalysis and optimization of different static mixer,make it able to adapt to the microcellularinjection molding process.(2) Numerical simulation studyAccording to the process mechanism of microcellular injection molding, construct thephysical and mathematical models, select the process parameters which effect therectangular plate products gaeatly (injection volume, melt temperature, mold temperature,injections time, initial gas content) as experimental factors, determine the range of processparameters by the moldflow window molding,then construct the orthogonal experiment tableto simulate,analyze the experimental results according to mean and standard deviationanalysis;based on the inquirment of pratical production, using comprehensive balance method to optimize the multi-targets performance.(3) Experimental studyUsing modified microcellular injection molding machine to do experiments, measurecell size and products warpage, compare experiment results with simulation results to verifythe reliability of the results of optimization simulation; cell morphology of the flow directionand the thickness direction is research and analyzed to verify the consistency of theexperimental results and the simulation results; Finally, the effects of different processparameters on the product weight is studied.(4) Process parameters optimization studyBased on the nonlinear mapping ability of neural network, using BP neural network totrain data and prediction, construct prediction models of targets and process parameters,andverify the reliability of prediction models. The choice of initial weights is random for neuralnetwork, lead to uncertainty of forecasting models;using genetic algorithms to dooptimization for neural network weights,further improve the predictive ability of model, andthen combined with neural networks and genetic algorithms to get global best processparameters.Final, select matlab to design the GUI software to achieve prediction results ofdifferent paremeters and obtain best process parameters,so as to better serve the productionpractices.