塑料电磁动态塑化挤出机的挤出功率研究与模拟

本文采用自行修正的Tanner本构方程研究了塑料电磁动态塑化挤出机中熔体输送挤出功率对振动力场的响应。建立了振动力场作用下熔体输送挤出功率的理论模型,以此为基础模拟塑料电磁动态塑化挤出机的挤出功率,并进行了实验研究,结果表明理论模拟能够在一定范围内反映实际情况,为塑料电磁动态塑化挤出设备的设计和生产应用提供重要的理论指导依据。     

动态成型注塑螺杆熔体输送能力的研究

根据动态注射成型时螺杆的工作特点，采用自行修正的Tanner本构方程研究了聚合物熔体在螺槽中的等温流动。同时，近似地给出了振动力场下注塑螺杆熔体输送能力的表达式，理论分析了振动参数对沿程压力降及动态成型熔体输送能力的影响。结果表明，振动力场使塑化过程中聚合物的粘度降低，流动阻力减小。沿螺槽方向的平均压力降减小，在保持成型条件不变的情况下，施加振动可以提高熔体输送能力。     

振动力场下聚合物熔体流变行为的响应与分析——I．毛细管压力降和熔体表观粘度

在自行设计的恒速型毛细管动态流变装置上，对聚合物熔体进行动态挤出实验。借助已建立的振动力场下聚合物熔体流变行为的表征公式，分别计算振动力场下聚合物熔体在毛细管壁处的剪切应力、剪切速率和表观粘度。与稳态挤出时相比，引入振动力场后，发现毛细管压力降、表观粘度均显著降低，且随着振动频率和振幅的改变呈非线性变化趋势，作者对此进行了深入分析。     

振动力场下聚合物熔体流变行为的响应与分析 Ⅱ．毛细管挤出胀大比和第一法向应力差

在自行设计的恒速型毛细管动态流变装置上，对聚合物熔体进行动态挤出实验。实时采集毛细管的挤出胀大值，借助已建立的振动力场下聚合物熔体弹性行为的表征公式，计算振动力场下聚合物熔体在毛细管壁处的第一法向应力差。通过对比分析有无振动场下以及不同振动强度下聚合物熔体的流变性能，找到聚合物熔体弹性行为对振动力场的响应规律。     

塑料电磁动态逆化挤出机的挤出功率研究与模拟

本文采用自行修正的Tanner本构方程研究了塑料电磁动态塑化挤出机中熔体输送挤出功率对振动力场的响应。建立了振支力场作用下熔体输送挤出功率的理论模型,以此为基础模拟塑料电磁动态逆化挤出设备的设计和生产应用提供重要的理论指导依据。     

单螺杆挤出机中熔体混合理论的研究

综述采用不同的函数对单螺杆挤出机中熔体混合过程进行描述的研究情况和新的混沌混合的研究进展，以及近几年来利用可视化和可视化技术对矣合物材料在挤出过程中的行为所作的观测和分析研究，指出在新型电磁动态塑化挤出机中，引入挤出加工全过程的振动力场，对熔体的混合起到了较好的促进作用。     

振动力场下聚合物熔体流变行为的响应与分析 Ⅰ.毛细管压力降和熔体表观粘度

在自行设计的恒速型毛细管动态流变装置上 ,对聚合物熔体进行动态挤出实验。借助已建立的振动力场下聚合物熔体流变行为的表征公式 ,分别计算振动力场下聚合物熔体在毛细管壁处的剪切应力、剪切速率和表观粘度。与稳态挤出时相比 ,引入振动力场后 ,发现毛细管压力降、表观粘度均显著降低 ,且随着振动频率和振幅的改变呈非线性变化趋势 ,作者对此进行了深入分析。     

振动力场下单螺杆挤出机聚合物熔融过程模拟

采用数值模拟方法对振动诱导挤出熔融过程中振动参数的影响规律做了深入系统的研究。利用大型通用有限元软件ANSYS作为汁算机仿真平台，利用振动力场作用下聚合物依时性非线性粘弹特性和自行修正的具有松弛谱特性的Maxwell本构模型，对振动诱导挤出熔融过程在不同振动参数作用下的响应情况进行模拟分析。结果表明在一定振动参数范围内振动力场的引入有利于加速熔融进程。     

入口速度振动对单管挤出口模熔体流动的影响

研究了塑料挤出过程中入口速度振动对挤出口模内熔体流变性能的影响规律。基于计算机流体力学理论,利用FLOTRAN软件对单管口模成型段熔体流动过程进行数值模拟,分析了振动力场作用下与稳态加工成型中口模成型段熔体压力场、速度场及温度场的分布情况。研究表明,沿熔体流动方向上叠加一个正弦振动的入口速度时,挤出压力、温度是周期性变化的;振动速度的引入可以提高挤出速度、降低挤出压力、加剧黏性生热,同时也能提高口模体积流率,而且随着振动幅值的增大,效果越来越明显。     

流变性对两种熔体共挤出的影响

利用有限元软件包POLYFLOW对两种熔体的二维等温共挤出进行了数值模拟，讨论了两种熔体的流变性对共挤出的流动情况，界面形状和挤出胀大的影响。     

振动力场作用下的单螺杆挤出机固体输送理论

在单螺杆挤出机中,通过螺杆的轴向振动将振动力场引入聚合物固体输送过程,提出振动力场强化固体输送过程的新概念.以螺槽中运动的物料为对象建立了振动力场强化固体输送过程的数学模型,并获得了物料沿螺槽方向输送的压力（密度）、速度的近似解析解.传统固体输送过程就是当螺杆轴向振动的振幅为零时的特例,此时的压力降与Darnell and Mol 理论一致,但不同的是物料速度及密度沿螺槽方向是变化的,从而修正了Darnell and Mol 固体输送理论.螺杆的轴向振动提高了固体输送平均压力,缩短了固体输送的长度,增加了固体输送角.透明料筒全程可视化实验挤出机证明了螺杆轴向振动确实缩短了物料固体压实输送所需的螺槽长度.     

Dependence of solids conveying on screw axial vibration in single screw extruders

In the single‐screw extruder, the vibration force field is applied to the solids conveying process by the axial vibration of the screw and the novel concept on the solids conveying process being strengthened with the vibration force field has been brought forward in this study. We establish the mathematical model that describes the solids conveying process with the vibration force field and obtain the approximative analytical solutions of the pressure and velocity of the solids conveying in the down‐channel. In the new theory, if the screw has no axial vibration the solids conveying pressure is the same as that of the Darnell and Mol theory, but the density and velocity of solids conveying along the screw channel is variable, which has modified the Darnell and Mol theory in which the density and velocity of the solids conveying along the screw channel was considered invariable. The results reveal that the axial vibration of the screw can increase the average pressure of solids conveying, decrease the channel length of the solids conveying section and increase the solids conveying angle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2998–3007, 2006     

Experimental Studies and Mathematical Modeling of Melt-Pulsed Conveying in Screw Extruders

This article reports on a theoretical and experimental study of melt-pulsed conveying in an extruder. Based on a modified Tanner model, in terms of a simplistic viscosity equation proposed for a pulsating flow, a theory of melt-pulsed conveying under the effects of screw vibration was formulated. An experimental study was also conducted. Special attention was paid to head pressure and screw characteristics. It was found that melt vibration leads to a reduction of head pressure, with further vibration producing further reductions; vibrations also weakened the screw characteristic. Compared with the experimental results, the mathematical equations showed a reasonable qualitative-predictive ability     

振动力场对高密度聚乙烯固体物料输送压力的影响

在自行设计的动态固体物料压实试验机上,对高密度聚乙烯固体物料分别做了稳态和动态压实试验,研究了振动力场对固体物料输送过程的影响。结果表明:有振动力场存在时,螺槽中固体物料的压力明显高于稳态压实时的压力;在振动力场作用下,在一定范围内,增大振幅或者提高振动频率,都能明显提高螺槽中固体物料的压力,且压力随时间增加上升得更快;振动力场的引入可以加速固体物料的压实,使螺槽中提早建立固体物料的输送压力,且使压实效果更好。     

Effect of the axial vibration of screw on residence time distribution in single‐screw extruders

An analytic model has been developed to analyze the residence time distribution of melt in the screw channel of the melt conveying section in a novel extruder of which the screw can vibrate axially. A comparison of the residence time distribution of melt in screw channel with and without vibration shows that the residence time of melt increases with the apply of vibration and the larger the vibration frequency and amplitude are, the longer time it will take the melt to travel through the melt conveying section, which is in favor of the improvement of the effect of melt mixing. POLYM. ENG. SCI. 46:198–204, 2006. © 2005 Society of Plastics Engineers     

新型螺杆挤出机熔体输送理论的研究

介绍了一种新型嵌套式螺杆挤出机。对熔体输送段进行了深入分析，把内螺杆的运动等效为螺杆轴的反向拖曳和螺棱的正向推力置换两部分作用，建立了对应的物理模型和数学模型，并得到了解析解。重点讨论了沿螺槽方向的流动和横向流动，并与普通单螺杆挤出机作对比，得到了螺杆和机筒同时旋转情况下的体积流率。结果表明，所建模型的解析解和文献中的实验数据较为吻合，当螺杆和机筒同时旋转时，熔体输送段的体积流率大大增加，横向流动和平行平板模型类似。     

A composite model for an intermeshing counter‐rotating twin‐screw extruder and its experimental verification

A composite simulation model of solids conveying, melting and melt flow in a closely intermeshing counter‐rotating twin‐screw extruder has been developed. The model is based on combining new melt conveying models with melting and solids conveying models, and the die is included into considerations. A general approach is applied using fully three‐dimensional non‐Newtonian FEM modeling for melt conveying to develop screw pumping characteristics which are implemented into the composite model. Several screw configurations are considered including non‐classical elements. Computations are made for axial fill factor, pressure, temperature, and melting profiles. The results are validated experimentally. POLYM. ENG. SCI., 55:2838–2848, 2015. © 2015 Society of Plastics Engineers     

振动力场作用下三螺杆挤出机计量段中聚合物挤出的模拟

建立了同向旋转三螺杆挤出机计量段实际流道真实尺寸的三维非牛顿模型，利用ANSYS软件中的FLOTRAN CFD分析功能对该流场进行数值模拟，分析了振动力场作用下挤出机计量段内的黏度分布、压力分布、速度分布以及振幅对流量的影响，同时与无振动状态的挤出特性进行了比较。研究结果表明：振动力场的引入使熔体黏度和流量呈周期性变化，熔体黏度降低，螺棱两侧压差随振幅增大而增大，剪切作用增强，分散性混合能力和分布性混合能力提高。