Polymer Ultrasonic Melting Plasticizing Rate Of Impact Factor Analysis

Micro Injection Molding (MIM) is one of the key technologies which promote the development of Micro Electro Mechanical systems (MEMS). The melt filling difficulty in micro cavity is the main challenge of MIM now. In order to solve this problem, this thesis studied the polymer's plastification process using the polymer's ultrasonic plastification testing equipment. The main research works are as follows:According to the requirements of polymer's ultrasonic plastification experiment, the current ultrasonic plastification equipment has been improved in the following aspects:by studying ultrasonic vibration system, the ultrasonic vibration mode was determined, and the static sealing method of the ultrasonic vibration tool was designed; pressure sensor determination method had been designed to determine the end of ultrasonic plastification, which provides a scientific and accurate method for the determination of ultrasonic plastification speed.Secondly, the process of polymer's ultrasonic plastification has been theoretically analyzed. There are three kinds of heat effects including friction heat effect, viscoelastic heat effect and ultrasonic cavitation effect. The numerical simulation has been taken on the gas bubble-wall equation of motion using Runge-Kutta method with the aid of MATLAB software. The relationships between ultrasonic frequency, acoustic pressure amplitude, the initial bubble radius, plastification pressure, melt viscosity and the ultrasonic cavitation effect have been obtained. And the numerical simulation also got a best combined parameters, which provided a theoretical basis for the following experimental research.Finally, the results of polymer's ultrasonic plastification experiments showed that the sensor determination method can accurately measure the polymer ultrasonic plastification speed. And polymer's ultrasonic plastification speed increased as ultrasonic power and plastification pressure increase. When ultrasonic power is 200 V, and plastification pressure is 2.0 MPa, the polymer ultrasonic plastification speed reached a maximum, that is 0.1111 g/s。The results also indicated that the ultrasonic cavitation effect is the most powerful effect of the three effects during polymer's ultrasonic plastification process. Experiments indicated that ultrasonic plastification process significantly improved the morphology of polymer than the heating plastification process. The experimental study laid an experimental foundation for the development of polymer's ultrasonic plastification technology.