The Monitoring Method of the Plastic Injection Molding Process Based on the Mold Cavity Pressure Measurement

Plastic injection molding has the advantages of high producing efficiency, stable producing equality, easy to mass production and complex product geometries, and thus becomes the most primary processing techniques in plastic industry. During the process, Mold cavity pressure has been recognized as a critical process parameter for the injection molding of high quality plastic parts. Mold cavity pressure sensing technology offers an effective method to help engineers scientifically analyze the processing procedure. Furthermore, the mold cavity pressure sensing technology can be used in monitoring the factories producing to enhance the product quality and the capabilities of replication, which brought significant outlook in industry application. Hence, this paper creates an approach to analyze as well as monitor the plastic injection molding procedure based on the mold cavity pressure sensing technology.   The theory of mold cavity pressure sensing technology is discussed in the chapter two. In order to get the precise data inside the mold during the processing, the research is focused on the aspects of work principles of the different pressure sensors, the right placement in the mold and the establishment of mold cavity pressure controlling system. A typical mold cavity pressure curve is given as an example to show the sequences to scientifically analyze the processing procedure, including the processing parameters can be shown on the curve.   The characteristics of curve shape are great influence by the processing parameters setting. Based on the self-developed mold cavity pressure measuring system, this paper chooses 4 main processing parameters of injection rate, mold temperature, packing pressure and packing time as the experimental factors, and adopt the one-fact complete randomized design method to run the experiments. The influences of processing parameters variation on the curve shape characteristics are summarized based on the experiments results.   In order to realize the injection process monitoring, it is very important to determine the standard mold cavity pressure curve of high product quality, and the suitable tolerance range of curve shape. This paper proposes a method to find out the standard mold cavity pressure curve based on the produce quality trials, and then discusses the determination of tolerance range of curve shape based on the statistical process control method.   According to the above research, this paper discusses the method of monitoring the plastic injection molding procedure based on the mold cavity pressure sensing technology, and gives out some examples about the procedures of processing parameters optimization used the mold cavity pressure sensing technology.