Design Of Injection Unit For Full-Electric Injection Molding Machine And Experimental Study On Plastic Product With Microstructure

With the progress of micro/nano science and technology, the development of miniaturization is increasing globally. Consequently, the miniaturization demand of polymer products is gradually increased in medical industry, aerospace industry, precision instruments, communication terminals and other applications. Meanwhile, the requirements are also keeping increasing in the processing of micro products, the variety of materials, production efficiency and other aspects. Micro injection molding technique is rapidly developing in the micro molding of polymers, metals and ceramics. Moreover, it has become a hot research topic in various processing technology of precision and micro structure products. All-electric injection molding machine driven by servo motor has been widely used in micro injection molding, owing to its high reliability, high response characteristics, high precision, energy-efficient, low noise, environmental protection and other properties. Along with the development of high density packaging and miniaturization of electronic industry, as a bridge connecting different circuits and electronic components, the connector keeps shrinking in different types of high-end electronic systems.Based on the investigation of all-electric injection molding machine which developed both at home and abroad, the preliminary injection unit of 1300kN all-electric injection molding machine was designed through theoretical calculation and 3D modeling in this study. The micro connector was taken as the research object of microstructure products. Numerical simulation and injection molding experiments were carried out to study the effects of processing parameters in injection molding on replication fidelity of micro connector. The main contents are as follows:(1) After learning the injection unit design and parameters of the same specifications all-electric injection machine which developed in both at home and abroad, the parameters of injection unit were determined by theoretical calculation and accessories selection (servo motor, ball screw, etc.). Then, according to the above parameters and parts selection, the initial structure design of all-electric injection unit was modelled with SolidWorks.(2) The warpage of the connector is one of the common defects in the injection molding process. Therefore, the numerical simulation was carried out for injection molding process of liquid crystal polymer micro connector by Moldflow. Moreover, warpage was chosen as evaluation indexes, and the simulation was designed by a L16(45) orthogonal array. Finally, the influences of injection molding parameters on warpage of micro connector were analyzed to obtain the optimal parameters, including holding pressure, holding time, melt temperature, mold temperature and injection speed. Furthermore, these parameters were optimized to reduce the warping deformation of the connector.(3) Liquid crystal polymer (LCP, grade:6130L-NC010) supplied by DuPont Company of America and polycarbonate (PC, grade:Lexan OQ2720-1111) supplied by SABIC were used to produce micro connector. And the experiment was conducted by Wittmann Battenfeld Ecopower 55 electric injection molding machine. Then, based on simulation results, melt temperature, mold temperature, injection pressure, injection speed, holding pressure and holding time were chosen to design the experiment with a L25 (56) orthogonal array, and the mass of the product was taken as assessment index. Eventually, the effects of processing parameters in injection molding on replication fidelity of micro connector were analyzed to optimize the processing parameters and improve the replication fidelity of the connector.