带捏合块的渐加速型单螺杆三维流场分析

目的:提高单螺杆挤出机的混合性能和工作效率.方法:设计了一种利用行星轮组件和混合元件的同轴渐加速单螺杆,利用Ansys/cfx对其流道进行了三维流场分析,得到了宏观压力场、速度矢量图、速度流线图以及轴向速度变化曲线并与传统单螺杆进行了对比,结果:随着螺杆转速的不断变大,物料在机筒内停留时间变短,渐加速螺杆的挤出效率得以提高20%～25%,使得耗能大大减少,由于捏合块的存在,物料在捏合块处被反复挤压,使得渐加速型单螺杆在增加产能的同时混合性能又可以得到保证.结论:同轴渐加速单螺杆高速旋转的捏合块可使物料混合更充分,且能缩短物料在螺杆中的停留时间,提高产量.     

基于CFX的同轴变速双螺杆挤出机三维流场分析

目的：分析物料在改良后的同轴变速优化双螺杆挤出机流道中的工作状态。方法：运用ANSYS/CFX模拟分析双螺杆挤出机流道数值,得到物料的运动情况,并与传统双螺杆进行对比,通过宏观压力场、宏观速度场、速度流线图、速度矢量图对比分析两种螺杆的性能。结果：同轴变速优化双螺杆的建压能力、混合性能明显优于传统双螺杆,通过中段的减速输送可有效延长物料运输时间。结论：新型优化双螺杆在保留传统双螺杆优势的情况下,额外提升了建压能力和混合性能。     

基于CFX的谐波减速优化双螺杆挤出机特性研究

为提高双螺杆挤出机挤出性能，结合谐波减速器，研究设计了一种内含谐波减速器的同轴异速优化双螺杆；用SolidWorks建模，导入ANSYS/CFX有限元分析模块，模拟物料在机筒内的流动状态，围绕宏观压力场、速度场分析，与普通双螺杆对比，并进行实验验证。结果表明：新型双螺杆的物料停留时间较之普通双螺杆提升15%左右；物料在输送过程中有物料交换现象；流道整体压力差几乎不受影响；实现了双螺杆挤出机混合性能的进一步优化。     

三螺杆挤出机中胶料流动的三维流场分析

利用 ANSYS软件包 ,分析了胶料在三螺杆挤出机中的流动情况 ,讨论了整个流道的速度分布、压力分布 ,并和双螺杆挤出机的挤出特性进行了比较。计算结果表明 :三螺杆挤出机的物料输运能力及混合能力都好于双螺杆挤出机     

基于ANSYS的带行星轮同轴变速单螺杆挤出机三维流场分析

运用ANSYS/CFX软件对带行星轮同轴变速单螺杆挤出机流道进行分析,并与普通单螺杆进行对比.结果表明:相较于普通单螺杆,新型同轴变速单螺杆挤出机的建压能力更好,物料在螺杆中的停留时间更长,有利于物料更好地混合,表明带行星轮同轴变速单螺杆可局部降低物料运输速度,增加物料混合能力以及螺杆建压能力.     

基于ANSYS的新组合型单螺杆挤出机特性研究

针对普通单螺杆挤出机剪切混合模式单一、工作性能差等问题，研究设计一种新组合型单螺杆。采用SolidWorks建模，ANSYS/CFX有限元分析和对比试验的方法；形成新组合型单螺杆流道整体压力差高于传统单螺杆1.22 MPa左右，物料在进出强剪切段过程中有回流产生，强剪切段物料输送速度较传统单螺杆加快0.012 m/s左右的结果；得出新组合型单螺杆挤出机在80?160 r/min的转速下，物料停留时间较传统单螺杆挤出机缩短5%?12%的试验结论。研究为高性能单螺杆挤出机的优化创新提供理论依据。     

同向全啮合双螺杆植物蛋白挤出机不同螺杆元件的仿真分析

为了明确和量化同向全啮合双螺杆挤出机各螺杆元件的功能,增加配置用于生产植物基肉双螺杆挤出机螺杆的合理性,以低温脱脂花生蛋白粉的物性参数为条件,对SLZ36型挤出机的3种元件长度为32 mm的螺杆元件双头螺旋元件、5啮合盘啮合元件及3齿形盘齿形元件的剪切速率、混合指数、物料停留时间、最大剪切应力分布进行仿真分析。采用Solidworks软件建立元件的几何模型,应用Gambit软件进行模型的网格划分及网格质量分析,在Polyflow软件中进行数值模拟,通过Fieldview软件对仿真结果进行后处理分析。结果表明：通过混合指数分析得到3种螺杆元件对物料的混合性能大小为齿形元件>啮合元件>螺旋元件;通过物料停留时间分析得到3种螺杆元件的轴向混合性能大小为齿形元件>螺旋元件>啮合元件;通过剪切速率及平均最大剪切应力分析得到对物料的剪切性能大小为啮合元件>螺旋元件>齿形元件。进行植物基肉双螺杆挤出机螺杆组合时,针对目前整个螺杆配置螺旋元件最多的情况,在进行物料更换时可以合理地配置啮合元件以增加螺杆剪切能力,配置齿形元件以增加螺杆的混合能力。     

丙纶纤维专用抗菌母粒的制备及其应用

介绍了一种专门用于制备抗菌合成纤维的抗菌母粒,采用含银共容组合物与高熔融指数的高分子树脂捏合,再与载体树脂共混,经双螺杆挤出机熔融挤出,切粒。采用本母粒与PP树脂混合,可制备出抗菌性能良好的丙纶纤维。     

涤纶纤维专用抗菌母粒制备及其应用

介绍了一种专用于制备抗菌合成纤维的抗菌塑料母粒,采用含银共容组合物与高熔融指数的高分子树脂捏合,然后再与载体树脂共混,经双螺杆挤出机熔融挤出、切粒.采用本母粒与PET树脂混合,制备了抗菌性能良好的涤纶纤维.     

二阶双螺杆挤出机流场分析

在阶梯状双螺杆挤出机参数一定情况下,利用三维软件建立实体模型,在ANSYS Workbench有限元软件Fluent模块中,分析阶梯状双螺杆挤出机中熔融段速度分布、压力分布、流体迹线分布的情况。     

啮合同向双螺杆挤出机不同螺杆构型对其流场的影响

目的：探究啮合同向双螺杆挤出机不同螺杆构型对流场的影响,改善聚乳酸的材料性能。方法：应用Solidworks软件建立双头螺纹元件的几何模型,在Polyflow中进行数值模拟,借助Fieldview软件对仿真结果进行后处理分析,并对比剪切速率场、压力场、速度场、黏度场以及停留时间分布曲线RTD,得出螺槽深度对流场的影响。结果：在中心距相同的情况下,通过改变螺纹元件的外径和内径之比改变螺槽深度,在相同的工艺条件下,同向双螺杆流道内各物理场以及混合性能均存在较大差异;与构型二相比,构型一的剪切作用更强,但构型二的建压能力更好;挤出过程中,构型二轴向混合能力较好但自清洁能力较差,而构型一轴向混合能力较差、自清洁能力较好。结论：螺槽深度的改变对流道混合性能有着一定影响且存在规律性,可有效指导双螺杆挤出机螺纹元件的设计。     

Analysis of the dispersive mixing efficiency in a twin-screw extrusion processing of starch based matrix

The flow of plasticized maize starch in a co-rotating twin screw extruder was simulated by using computational fluid dynamics (CFD). Sensitivity of the simulation to the selected viscosity model was analyzed. The results suggest that about 16 times increase in zero shear viscosity has no influence on the flow, whereas a slight change in viscosity at the shear thinning region leads to significant increase in pressure drop along the mixing zone of extruder. Simulation results were validated quantitatively by experimental data. Furthermore, the flow type and profile in the extruder were discussed by using the influence of screw speed and screw configuration as exemplary process parameters. To evaluate the dispersive mixing efficiency, material specific critical capillary number was implemented into particle tracking simulations. Maximum shear stress generated at the tip of the screws was used to calculate the maximum capillary ratio, and therefore to determine the dispersive mixing efficiency. The results show that increase in screw speed led to better dispersive mixing, although the generated shear stresses decreased. To investigate the influence of screw geometry, two different screw configurations were simulated. The results show that the dispersive mixing efficiency can be improved by using reverse kneading blocks at which more particles are exposed to high shear stresses.     

Residence time distributions in extrusion-cooking. Part IV the feed zone of a conical,counter-rotating,twin-screw extruder processing maize grits

The residence time distributions in the feed zone of a counter-rotating, twin-screw extruder processing maize grits, were measured by means of a ⁶⁴Cu tracer. The detection system was mounted above the transport zone of the extruder. Three different screw pairs were investigated. The residence time distribution measurements were analysed by means of an axial mixing model developed for a twin-screw extruder. The feed rate was found to be the most important variable affecting the average residence time. The average residence time was inversely proportional to the screw speed. Measurements could be simulated by assuming backmixing action over approximately 15% of the axial length of the screw. Geometrical devices in these screw pairs, such as kneading zones and so-called drossel zones (high-shear throttle valves), resulted in a significant increase in the average residence time. Their action can be simulated by means of an axial plug-flow model.     

不同螺杆接触状态下异向双螺杆挤出机的流道分布规律

目的:探索聚乳酸在异向双螺杆挤出机不同螺杆接触状态下的流道分布规律。方法:用Solidworks软件建立啮合螺杆、部分啮合螺杆和非啮合螺杆3种几何模型;运用POLYFLOW流体仿真软件进行数值模拟;对3种螺杆不同接触状态下聚乳酸流体的压力场、剪切速率场与黏度场进行对比研究。结果:部分啮合状态下的异向双螺杆挤出机对聚乳酸有较好的建压能力与分散混合能力。结论:聚乳酸在部分啮合状态下的挤出效果优于其他2种螺杆接触状态。     

EFFECT OF EXTRUSION OPERATING PARAMETERS ON AIR BUBBLE ENTRAPMENT

The effect of different extrusion operating parameters on air bubble entrapment during twin‐screw extrusion of amylopectin half‐products was studied. A ZSK‐30 twin‐screw corotating extruder with a slit die attached to the discharge end of the extruder to cool the extrudate to prevent water vapor puffing was used. The extrusion parameters investigated were screw speed (150, 300 and 500 rpm), mass flow rate (1.67 and 3.33 g s^?1), native versus pregelatinized amylopectin, screw configuration (with or without kneading blocks), and moisture content (32 and 35%, w.b.). The parameters that exerted the greatest effect on air bubble entrapment during twin‐screw extrusion are the type of amylopectin used, mass flow rate and screw speed. On the other hand, in the ranges studied screw configuration and moisture content did not show any significant effect on air bubble entrapment. Explanations for these results are interpreted with the aid of the barrel fill length mechanism proposed by Cisneros and Kokini (2001).     

加工参数对棉籽饼粕双螺杆挤压脱毒的影响

利用双螺杆食品挤压机对棉籽饼粕进行了挤压脱除棉酚的试验，考察了加工参数对脱毒效果的影响。结果表明：增大螺杆转速，脱毒效果变好；减小含水量，脱毒效果变好；增大螺杆转速，产量增大；增大含水量，产量增大；捏合盘的加入能有效改善脱毒效果，捏合盘长度和位置是影响脱毒效果的显著因素。试验结果还表明，双螺杆挤压机用于棉籽饼粕挤压脱毒，效果十分显著。     

不同温度状态下啮合异向双螺杆挤出机的流道分布规律

为探索等温与非等温状态下啮合异向双螺杆挤出机的流道分布规律,采用Solidworks三维建模软件建立啮合异向双螺杆的物理模型,在Polyflow分析软件中进行相应的数值模拟。结果表明:在等温问题中,随着双螺杆转速的增加,出口方向上的压力、黏度、剪切速率变化趋势不同;在非等温问题中,挤出方向从入口到出口温度呈线性增加的趋势,并且沿着径向向外的方向,温度逐渐增加。