Warping Deformation Research Of Injection Molding Of Plate Plastic Parts Based On Moldflow

With the plastic parts widely used in our daily life and industrial production, people concern plastic parts molding quality increasingly. Warping deformation as a serious defect affecting the quality of products, especially for plate parts having poor ability to resist deformation, the defects of warping deformation is more serious. The formation cause and the solution of warping deformation is being widely studied, compared with the traditional mold desig n and the test method, the computer aided engineering based on numerical simulation and computer graphics technology is gradually widely used, which has a great guiding significance to improve the production efficiency, reduce the production cost and warping deformation degree, improve the molding quality of plate parts.This article first briefly described the engineering application and common defects of injection molding, the theory and engineering practice research of warping deformation at china and abroad, analyzed the viscosity model in injection molding process and rheological properties of pseudo-plastic fluid, the flow properties of melt in different cross sections, these theories provide theoretical basis for the flow analysis of the melt in gating system and cavity shape. Then emphatically studied the generating reasons, influence factors, improvement measures of warping deformation, Drawn a conclusion that the mainly generating reasons of warping deformation are uneven contraction, inconsistent molecular orientation, the release of residual stress; the influence factors of warping deformation degree are material properties, product design, mold design and molding process; the measures to reduce the warping deformation degree mainly from product design, mold design and molding process of the three aspects.On the basis of the previous analysis about warping deformation, use a file-board as the research object, establish three-dimensional model of the research object by Pro/E software, import it into mold-flow analysis software, set the pouring and cooling system, the material properties and production process parameters, then a complete set of production environment was built for simulation. Four different forming schemes were established at preliminary stage, through the comparison of schemes, a relatively good forming scheme was selected and carried on preliminary analysis. Its warping deformation is 2.172 mm. According to the result of preliminary analysis, the warping deformation reduced to 2.009 mm by expanding product radius, increasing the stiffener floor in product design aspect; the warping deformation reduced to 1.747 mm by tu ning pipe number and location, the size of the diversion channel in the mould cooling and pouring system, thus the cooling is more uniform, melt flow more balanced; combined with orthogonal experiment method, developed a orthogonal test table with five fac tors and four levels, through the range analysis and variance analysis about orthogonal experiment results, we know the influence degree sequence of injection molding process on warping deformation is holding pressure > holding time > injection time > melt temperature > mold temperature, the optimized combination of molding process made the warping deformation reduced to 1.645 mm. In view of the important influence of holding process on warping deformation, the further optimization divided the constant holdi ng pressure into piecewise holding pressure and refined holding pressure parameters, the warping deformation reduced to 1.303 mm eventually, reduced by 40% compared with the initial warping deformation.The research of this paper indicates that it is able to reduce warping deformation degree of plate parts effectively through basing on computational flow analysis, combing with the theory of orthogonal test, making research and taking improvement measures from material properties, product design, mold design and injection molding process aspects.