Numerical Simulation And Quality Control Of FIFO Injection Molding Machine

Injection molding is an important technology in modern plastic technology. On account of light weight, low price and good comprehensive mechanical properties, plastics get widely used in such industries as mechanics, electronics, aviation, automobile, communication and so on. Industrial parts are usually requested to have high precision and complicated shapes, so it is important to control the plastic parts quality. Product quality subjects to injection molding machine, material performance and process parameters. The present dissertation pays attention to the injection molding machine designing, polymer processing simulation, and the optimization of processing conditions. The FIFO injection molding machine is designed; the mathematical models and numerical algorithm are developed for processing simulation; the modern optimization algorithms and numerical simulation are integrated to optimize processing conditions; the qualities relations between processing parameters and mechanical behaviors are determined; and quality control is finally implied.1. Injection molding machine is very important for processing technology, whose technical parameter and performance is related to plastic character and injection molding processing. Two important units' structure (injection and clamping unit) is anglicized. For injection unit, this design places screw into injection ram in order to realize FIFO injection; for clamping unit, combing the pressure-charged and liquid-filled clamping unit's merits, this design adopt self-feeding valve to complete clamping, whose clamping precision is high and closing pressure is large. Besides the reliability, precision and cost, this design emphasizes injection molding machine's floor space.2. Following the principle theory of viscous flow, the dimensions of physical and geometrical variants in filling and packing phase are analyzed; the filling and post-filling stage's governing equations are obtained. A hybrid finite-element/finite-difference and the control volume method is employed to solve the equations, not only to obtain the pressure, temperature and shear rate field, but also to predict forming detects.3. A new design of experiment- fractional factorial design is put forward to study the interaction effect between process parameters. So the important interaction and single factors are screened to put into orthogonal table and to optimize the processing parameters.4. After the fractional factorial design, An L₂₇ experimental matrix design based on Taguchi method is performed to optimize injection molded parts. The part weight, volume shrinkage and sink marks are selected as quality index, and the relationship between mold temperature, melt temperature, holding pressure, holding time and quality index are determined. 5. An artificial neural network with numerical simulation is used to optimize injection molded parts' quality, and the qualities relations between processing parameters and mechanical behaviors are determined. This method overcomes the drop-out of regression method.6. Experimental verification is conducted to certificate the numerical model created by design of experiment and artificial neural network. The results are coincident. This showed analyzing and optimizing of injection molding processing by simulation method had important reference to production of molded parts and design of molds.