Part Quality Control For Plastic Injection Molding Based On Pressure Pattern

Plastic injection molding is an important processing technology and is suitable for producting plastic products with complex shape and accurate dimensional request. High part quality demands are requested with the application of products injection molding in variable fields. In molding process, state variable impact on flow state of melt in cavity and final quality of part directly. However, simulation of molding can only replace the trial-and-error and the correct also depend on the designer's experience. It is difficult to get the best process condition, and the influence of disturbance make it more difficult to get consistent good quality parts. The investigation of on-line quality control for injection molding can make the molding keep on the desirable level and produce high quality parts consistently, and is very valuable practically. The paper focus on part quality control research based on pressure pattern. The following works have been finished:1. Pressure pattern recognition. Pressure curve in the cavity has great influence on the injection molding process. The part quality can be controlled well by monitoring the whole pressure pattern. Using pattern recognition technique can recognize the pressure pattern in injection molding. The relationship between pressure and time is established by using polynomial representation and sub-pattern analysis. The pressure pattern can be recognized by defining the coefficient of the polynomial in every sub-pattern, and the coefficient is input and output of the ANN.2. The ANN model foundation. The control variables are selected based on significance of processing parameters, and the process and part quality characteristics are extracted using simulation results based on baseline condition of near optimized condition. The relationship models of processing parameters with state pressure pattern and pressure pattern with quality indexes, which is the base of part quality control, are built by ANN technique3. Part quality control in injection molding. The relationship among the process characteristics, the state variable of the melt in cavity, and the part quality indexes are investigated based on the pressure pattern. Closed-loop part quality control strategy...