Research On Online Measuring Method Of Repeated Precision Of Polymer Injection Weight Based On Ultrasonic Technology

Now more and more polymer precision products have being applied in aerospace, medical equipment, biological engineering, precision optical, electronic communications and other sophisticated technical field. This is a higher requirement for the quality of the polymer molding products, and the factors affecting the quality accuracy and how to evaluate the quality of molded products scientifically and effectively is the premise of improving the quality of the molding. Injection weight repeatability precision is an important technical index to measure the quality of injection molding products and evaluate the performance of injection molding machine. In this paper, according to the definition of the injection weight, the main factors affecting the injection weight is analyzed, which bases on the all-electric injection molding machine injection mechanism of mechanical transmission mechanism and control mechanism, and theoretical study on the basis of statistical process control and the theory of error analysis of injection repeating weight precision on-line measurement method are carried out. The ultrasonic technology of polymer melt density soft sensing model is applied in injection process of injection weight online measurement, and injection repeating weight precision on-line measurement to improve the feasibility of injection repeating weight precision is verifies by experimental study. At the same time, based on the whole electric injection molding machine, the control method of the repeated precision of injection weight is studied theoretically. Main content is as follows:1. Based on the drive and control principle of all electric injection molding machine injection system of mechanical transmission, various factors that influence the quantity and quality of the injection volume are analyzed, and base in the strict control of the injection volume, it is found that the temperature and pressure change are the main factors which affect the weight of the final injection.2. Based on statistical process control and the theory of error analysis, the algorithm of the repeatability of the injection weight is theoretical analyzed. Based on the analysis and comparison of error algorithm and number of samples, the injection of repeating weights precision on-line measurement method is studied.3. On the basis of experimental, the ultrasonic wave velocity and density of the melt soft measurement model is established, and its application in injection molding. Through the different craft condition of injection of online measuring weight, the revision to the melt density soft sensing model is carries on, which bases on the analysis of comparative measurement theory value and measured value of the error factors. On the basis of experimental injection repeating weight precision on-line measurement method are analysis and verification.4. On the basis of experimental and theoretical analysis, the online measurement of the injection weight soft measurement model is modified online, and the method is studied based on the accurate control of the injection weight of the whole electric injection system.