【作者】 周伟安；

【导师】 应济；

【作者基本信息】 浙江大学 ， 机械制造及其自动化， 2010， 硕士

【摘要】 随着塑料制品应用范围的扩展,精密塑料注射成型装备的开发,是国内企业一直追求的目标。电液控制系统是精密注塑机难以解决的核心技术之一,决定和制约注射成型装备性能的提高,关键是在于控制系统和参数存在严重的时变、非线性及熔融负载复杂不确定因素。因此,注塑机电液控制系统的设计与控制研究具有重要的应用价值。本论文依托国家科技支撑计划项目“精密塑料注射成型装备关键技术的研究与产业化”的子课题开展研究工作,具体内容如下:1)论述注塑机液压控制系统及其自动控制策略的发展现状和技术特性,给出了注射电液控制系统的复杂性和控制难点。2)根据精密注塑机的工作原理和技术要求,提出以伺服比例阀为核心控制元件的闭环电液比例伺服注射控制系统;根据流体传动原理对系统进行了数学建模,得出相应的非线性微分方程组;利用Matlab/Simulink软件平台对系统的关键元器件建立仿真模型,并将其组成整个注射控制系统,分析系统的工作特性。3)基于电液控制系统中存在的非线性特性和熔融负载的不确定性,提出Fuzzy_PID复合控制和积分分离式PID算法分别控制注射过程中的螺杆速度和保压压力,并通过Matlab/Simulink对系统和控制策略进行仿真分析研究。4)将开发的系统应用于HTH注塑机中,进行注射速度、螺杆位置、保压压力和重复精度的试验研究,并与海天JU2000伺服注塑机进行同条件下的注射实验结果进行比较。结果表明,注射速度和保压压力的曲线跟踪性能很好,响应速度快且平稳,超调量小,整机和制品的精度得到明显提高。更多还原

【Abstract】 Along with the development of plastic industry, domestic enterprises devote great effort to developing and manufacturing precision injection molding machines, to reduce the injection technology gap with foreign machines. As one of the most critical technologies, electro-hydraulic control system constrains the injection performance improvement. The time-variant, nonlinearities of control parameters and uncertainties of thermoplastic during molding process make it hard to precisely control the system and product. Therefore, research on mechatronic design and control of electro-hydraulic systems for precision injection molding has significant utility.The research subject is a part of the National Science and Technology Support Project named ’Research on the Critical Technologies for Precision Plastic Injection Molding and Industrialization’. The content of this dissertation is arranged as follow:1) The development and technology characteristics of hydraulic control systems and automatic control strategies for injection molding are expounded in the paper. Then the control difficulties of electro-hydraulic injection process are presented.2) According to the requirements of precision injection molding, a new closed-loop electro hydraulic injection system is presented which controlled by a closed-loop proportional valve and an AC servo motor. On the basis of the operating principal of the proposed system and hybrid theory, an equivalent mathematic model of the main hydraulic loop is built to get the nonlinear differential equations, and then a simulation block diagram of the whole injection system is established in Matlab/Simulink. The mathematic model is linearized, so as to verify the stability, controllability and observability of the system.3) In order to compensating nonlinearities of electro-hydraulic injection control system and uncertainties of the thermoplastic, the overall control scheme is presented in this dissertation. That the injection velocity is controlled by Fuzzy_PID control algorithm and the packing pressure is controlled by Integral-Separated PID algorithm. To verify control performance of this system, a serial of simulations on injection velocity and packing pressure are made to compare with traditional control algorithm by Matlab/Simulink. The simulation results show the advantages of this system and control method in dynamic and static characteristics. 4) The application of closed-loop electro-hydraulic injection system is studied in HTH200 servo injection molding machine. Experiments on this machine are carried out to evaluate the effectiveness of injection velocity and pressure control. As experimental results show, the velocity and pressure tracking performance is very satisfactory with fast response, small overshoot and high steady precision. Furthermore, experiments about repeatability accuracy including the position of injection screw and the weight of plastic product are carried out to verify the proposed electro-hydraulic system and control method.更多还原