Study On Ultrasonic Micro Plasticizing Mechanism And Its 1g's Injection Molding Device

Micro injection molding has become one of the main molding methods in MEMS(microelectromechanical systems)due to the advantages of one-time molding,high efficiency,low cost,suitable for large-scale production and good molding products.It is widely used in various fields such as medical and health,precision instruments,aeronautical aerospace,information communication and so on.At present,micro injection molding technology mainly uses screw plasticization and few uses plunger plasticization.The former has problems of difficulty in machining small diameter screw,inhomogeneous plasticization,more than required injection amount of single plasticization,short life span of small diameter screw and difficult filling of melt,and the latter is poor in plasticizing effect and is also faced with the problem of melt filling.Micro injection molding technology based on ultrasonic plasticization can solve these problems well,and can greatly reduce energy consumption,simplify injection molding equipment and reduce cost.Therefore,it has become the focus of research in micro injection molding.On the basis of previous studies,theoretical and Experimental Research on ultrasonic micro plasticization mechanism is carried out in this paper,and single chip ultrasonic micro injection device is designed.The main research contents as follows:(1)The effect of ultrasonic friction heat generation and ultrasonic viscoelasticity is analyzed theoretically.In view of the ultrasonic cavitation effect,the four order Runge-Kutta method and MATLA software are used to simulate the influence of the parameters in the ultrasonic cavitation effect and the better process parameters based on the RPNNP equation of motion of the micro bubbles in the elastic liquid under the action of sound waves.(2)ANSYS is used to simulate the temperature change during polymer plasticization.Only the effect of ultrasonic energy flow is considered,and the material is LDPE.The ultrasonic energy flow is acted on the polymer model from the top,and the plasticizing process is explored.(3)Referring to the research results at home and abroad,the design of an ultrasonic micro injection molding system is determined,and the main performance parameters of the ultrasonic injection molding system are calculated,that is,the main performance parameters of the plasticizing part and the injection part.According to the previous scheme and calculation,a kind of ultrasonic micro injection molding system is designed:first of all,the injection system is used.The ultrasonic system is designed,the main ultrasonic tool head is designed,and the other key parts of the ultrasonic system are designed and selected.Then the servo drive system,the plasticizing cavity and the mold are designed.Finally,the whole ultrasonic micro injection molding system is modeled.(4)Simulate the design of the tool head and the whole injection device,and explore its rationality.ANSYS software is used to analyze the vibration of the ultrasonic tool head.That is,using modal analysis and harmonic response analysis to simulate the parameters of its vibration mode,natural frequency and amplification factor to verify the rationality of the tool head design.The kinematics and dynamics of the injection process are simulated with ADAMS software,and its displacement,velocity,acceleration,and acceleration are obtained.The parameters of torque and injection force are used to verify the rationality of the design of injection molding device.(5)Through self designed and built experimental platform,LDPE was chosen as raw material for ultrasonic plasticizing experiment.The influence of two technological parameters on plasticization of plasticizing pressure and plasticizing time is explored,and the better process parameters are obtained.Meanwhile,the ultrasonic plasticization process is explored.