| With the wide use of injection molding parts, the quality of the productshas been improved. Weight repeating precision of products is an importantpart of quality, so reduce the weight fluctuation can improve products quality.This paper offer a new quality parameter: injection work. The definition ofinjection work is the integral of injection velocity and injection pressure timesthe filling time. It can characterize the melt viscosity and can characterize theproduct weight.Build up an online data acquisition system for injection work. it can getreal-time injection work data, which can provide a platform for injection workexperiments.The equations of injection work are established. According to theequations of injection work, injection work can characterize the melt viscosity.Two premises should be satisfied simultaneously:(1) constant injectionvelocity;(2) same integral time. Constant injection velocity and same integraltime are feasible in theory. It can characterize the melt viscosity and cancharacterize the product weight. A study on the injection work was made experimentally using the dataacquisition system. First，constant injection velocity can be validated by singlefactor. Then effects of process conditions on the time of constant injectionvelocity were studied by DOE method. The experiment results demonstratethat integral time is the same time during the constant injection velocity period.The conclusion that the injection work and the product weight have the sametrend by single factor experiment(process temperature, back pressure, screwspeed).The corresponding relation between changes of the injection work andthe changes of product weight is established. The corresponding relationbetween changes of the back pressure and the changes of product weight isestablished. Through changes of the injection work characterize the changes ofproduct weight, the changes of the back pressure make up for the changes ofproduct weight, so the part weight control system is established. |
PDF Full Text Request