Numerical Analysis And Experimental Study Of Extrusion Assisted By Ultrasonic Vibration

Extrusion is an important method of mass production of polymer parts, but the traditional polymer extrusion process has many shortcomings, such as the molding surface often exists "sharkskin", products section size and extrusion die size is not consistent, and other issues. In recent years, ultrasound is widely used in the field of polymer processing, ultrasonic vibration can not only improve the processing properties of the polymer, reduce energy consumption, increase production, but also improve the surface quality and dimensional accuracy of extruded products, improve the mechanical properties of products, and improve product microstructures. Currently, the mechanism of ultrasonic vibration is not yet completely clear, and the ultrasonic assisted extrusion die structure is too simple. This paper summarizes the theory on the basis of previous studies, and several key issues of polymer extrusion assisted by ultrasonic vibration have been studied. The main contents and conclusions were as follows:(1) According to the requirements of ultrasound-assisted polymer extrusion experiments, the ultrasound-assisted polymer extrusion experimental devices have been designed and an experimental study was conducted. The structure of the ultrasonic tool head was confirmed using the way of combing traditional design theory with Ansys simulation method and the rationality of the structure has been validated by simulation and experiment. Ultrasonic assisted extrusion capillary die has been designed to ensure that the ultrasonic tool head closely connected with extrusion die. And the experiment has been completed under the condition of ultrasonic work stability without leakage material. By ultrasound-assisted polymer extrusion rheological experiments, rheological data of polymer has been obtained under ultrasonic vibration, and the power law constitutive equation of the polymer has been obtained after sorting and fitting the data.(2) Numerical simulation analysis of polymer extrusion assisted by ultrasonic vibration has been conducted. For the first time the numerical simulation of non-Newtonian isothermal flow has been completed by using the Polyflow load function of transient boundary condition. The distribution of the pressure field, velocity field, shear rate field and the viscosity field of the melt have been obtained in the runner. Good consistency between numerical simulation result and experimental results of ultrasound-assisted capillary remoter.(3)The micro-extrusion die in which the orthogonal ultrasonic vibration introduced has been designed. And the experimental study on ultrasound-assisted micro-extrusion has been conducted. The rationality of the design of ultrasound-assisted micro-extrusion die has been validated. The impact of ultrasonic vibration and process parameters on the performance of micro-extrusion has been studied.