Intelligent Monitoring Technology For Consistency Of Injection Molding Process

Ensuring the consistency of product quality during the plastic injection molding process is the key to efficient production.However,in actual production,fluctuations in the external environment,wear of machines and molds,and changes in material properties may cause production fluctuations.Direct measurement of product quality indicators such as key dimensions has high labor costs and low efficiency,and there are certain Lag,can’t feedback the production status in time.With the rapid development of sensing technology and intelligent methods,real-time monitoring of product quality fluctuations through the pressure,speed,and temperature curves of the injection molding process has broad application prospects.In this paper,aiming at consistency monitoring of the injection molding process,a systematic study of the sensing technology and intelligent analysis methods is carried out.The main innovations are as follows.This paper puts forward the idea of simultaneously collecting machine operating variables and mold melt condition to monitor the forming process consistency,and builds a set of forming consistency online data collection system,which provides the software and hardware foundation for data analysis to online sorting.Firstly,a multi-channel acquisition hardware system was designed based on the analysis and selection of the machine operating variables and the mold melt state signal source,which solved the lack of input and output interfaces of most current process signal acquisition systems and designed a communication architecture based on the MQTT protocol.With secondary development capabilities through many-to-many communication and improved scalability.A phased feature statistical extraction method based on statistical values is proposed,which solves the problems of high dimensionality,time correlation and linear inseparability of collected data.In view of the high dimensionality of the injection molding process curve,as the input is linear and inseparable,the molding process is divided into multiple stages,the statistical features are extracted,and the feature distance value is used as an index to measure the difference between batches.The effectiveness of this feature extraction method is verified by actual production cases of precision lenses in enterprises.The correlation analysis of the injection molding process curve and the corresponding sampling product quality data for one week of continuous production in the real production environment shows that compared with traditional empirical characteristics such as peak values,integral values,and commonly used statistical values,the distance of statistical characteristics is better than the empirical characteristics.18% improvement in product quality relevance.Based on the above data collection and forming process feature analysis,two methods of PCA online monitoring and feature distance value monitoring based on staged feature extraction methods are designed to monitor the forming process consistency.Designed a production fluctuation test caused by different factors,and analyzed the sensitivity and realtime monitoring of the two methods.The test results show that both methods can effectively monitor the quality change caused by fluctuations in different working conditions,and the characteristic distance value is online.The monitoring sensitivity index is 16% higher than PCA online monitoring.It is proved that the use of feature statistics and characteristic distance value monitoring can effectively solve the problem of linear inseparability of the original data caused by the use of the original data due to non-compliance with the Gaussian distribution assumption.Based on the above research,a set of intelligent monitoring system for the consistency of the injection molding process was designed and developed,and an on-line monitoring experimental platform for the process consistency was established.The effectiveness of the intelligent monitoring technology for the consistency of the injection molding process was verified by the transmission screw products.This system can realize weight control of transmission screw products at least(-6 * 0.014 g,3 * 0.014g)due to the holding pressure speed and time.