【作者】 张澎湃；

【导师】 孙铁铠；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2004， 硕士

【摘要】 本文对啮合同向双螺杆挤出机螺纹流道中熔体全充满区的流动进行了全三维非牛顿等温模拟。由双螺杆几何学建立了螺杆的数学模型，并根据挤出机的实际几何尺寸对模型进行修正，所建立的模型与挤出机的实际尺寸一致。对于速度边界，采用无滑移边界条件，与机筒粘结的物料速度为零，与螺杆粘结的物料速度等于螺杆表面速度。对于流道进出口，采用压力边界条件。应用ANSYS软件进行有限元求解，得到螺纹流道的速度场、压力场、粘度场。通过计算得到的粘度场，由物料的本构方程反推出流道中的剪切速率场和剪切应力场。本文给出了计算拉伸速率、剪切速率和剪切应力的具体方法，并编制后处理程序对上述量进行计算。提出了一个关于流量、回流量计算方法，该方法简单，易于理解和计算。为了能充分解释挤出特性与各参数之间的关系，本文采用对离散数据结果进行统计和作图相结合的方式分析了螺杆转速、进出口压力差、机筒与螺杆间隙、螺距、无量纲槽深以及物料特性参数对流量、回流量、剪切速率、拉伸速率、剪切应力、平均剪切强度等挤出特性的影响。更多还原

【Abstract】 This thesis is concerned with three-dimensional non-Newtonian isothermal flow simulation of melts in full filling region of the flight element runner belonging to intermeshing co-rotating twin screw extruder. The math models of the screw were established based on twin-screw geometry.In order to possess the models the same dimension with the co-rotating twin screw extruder, the math models of the screw curve based on actual geometry dimension of the twin screw extruder have been developed. And meanwhile, a condition of boundary with non-slip is supposed for the velocity boundary. The mass velocity is restricted to ‘zero’ as the materials adhere to the barrel wall, and it is equal to the surface velocity of the twin screw while the materials adhere to the twin screw’s surface. Pressure boundary conditions are chosen for the inflow section and outflow section of the twin screw extruder. ANSYS, the software involves with finite element method, was adopted for solving the flow models and gaining results of the velocity flied, pressure filed, and viscosity field. Through deduction to the constitutional equation of viscosity, field and shear stress field of the runner were achieved. An idiographic measure was brought forward, as well as some compiled post processor programs were used to closely calculate elongation rate, shear rate and shear stress. A measure, in connection with flow and circulatory flow, which is simple to compute with and easy to comprehend, was adopted in this thesis.In order to fully explain the relationship between extrusion characteristics and analytical parameters, the method of connecting figure with table was chosen in this thesis. Analytical parameters including screw rotate speed, press difference between inflow section and outflow section, clearance between barrel wall and screw surface, mass peculiarity and non-dimensional depth of screw groove, etc, were carefully analyzed. The effect on the extrusion characteristics such as flow, circulatory flow, elongation rate, shear rate, shear stress and mean shearing intensity, etc, caused by the <WP=6>parameters mentioned above was analyzed, too.更多还原