| The main style of injection machine in injection molding industry is full hydraulic injection molding machine at present. Three-phase asynchronous motor drives pump with constant speed in the injection molding process, each action in injection molding process depends on the valve control system. However, the hydraulic flow and pressure of each injection process are changing during the injection molding. Most of the hydraulic oil is wasted through the throttle and overflow, which is mainly reason of the large energy loss in the injection molding industry. The main goal of this research is to design an electro-hydraulic servo control scheme of a clamping system of injection molding machine for the hydraulic injection machine. This servo scheme will avoid high pressure throttle loss and overflow loss in the process of clamping, at the same time, electro-hydraulic servo drive and can improve the efficiency and precision of injection molding. The main research contents of this paper are as follows:Firstly, the development and research status of the injection molding machine are analyzed, and the driving mode of the injection molding machine is introduced. the characteristics of the hydraulic injection molding machine, electric injection molding machine and electro-hydraulic hybrid injection molding machine are comparative analyzed, and the strong research necessity of the electro-hydraulic hybrid injection molding machine is put forward, the electro-hydraulic servo transformation principle for full hydraulic injection molding machine are initially introduced.Secondly, the basic mechanism of hydraulic injection molding machine and working principle are introduced. The proportional potential valve of the hydraulic lifting technology for energy saving are introduced through the analysis of process control of injection molding machine. The structure characteristics and working characteristics of double toggle clamping mechanism are analyzed and then the detailed scheme of hydraulic servo system is designed.Then, according to the operation and control demand of the clamping system, the hydraulic model of electro-hydraulic servo control system for clamping system is build using AMESim hydraulic simulation software, and control model electro-hydraulic servo control system for clamping system is established using MATLAB/simulink; the clamping hydraulic servo control strategy is designed considering of the different demand of work flow and hydraulic pressure during the process of injection molding to meet the decoupling control of hydraulic pressure and flow. Self-tuning fuzzy PID control method of the hydraulic pressure controlling is used in the hydraulic pressure control status, and a fuzzy PID controller is established in MATLAB/simulink; taking advantage of AMESim software and MATLAB/simulink software respectively, simulation is carried out, and the pressure curve of clamping system model is analyzed.Finally, the hardware circuit and software system of hydraulic servo for clamping of injection molding machine are designed based on TMS320F2812 DSP. The servo control system is applied to the technical transformation for a certain type of injection molding machine, and products of injection experiment has a good manufacturing precision and repeat precision of weight. The experimental results show that the clamping hydraulic servo technology of injection molding machine can be applied to practice. |
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