锥形双螺杆挤出过程菠萝型混合元件三维流场分析（I）

应用ANSYS有限元软件对锥形双螺杆菠萝型混合元件进行了三维等温非牛顿流场的模拟分析，并与常规螺纹元件的流场分析结果进行了对比，得出了波萝型混合元件比常规螺纹元件生产率高，分布混合能力强，其分散混合能力稍弱于常规螺纹元件的结论。     

啮合同向双螺杆螺纹元件几何参数对其在流场中受力关系的影响

使用POLYFLOW软件对啮合同向双螺杆挤出机中螺纹元件的三维等温流场进行了连续转动情况下的数值模拟。结果表明：螺纹元件在连续转动过程中受到的轴向力和扭矩会产生波动，并给出了螺纹元件承载能力的计算方法。引入单位长度受力的概念后，讨论了流量变化和流量一定的情况下不同中心距和不同导程的螺纹元件受力的变化。     

同向双螺杆不同螺纹元件混炼效果的数值研究

采用Polyflow软件数值模拟了啮合同向双螺杆挤出机流道内聚丙烯(PP)熔体的流动,数值计算了常规螺纹元件和开槽螺纹元件流道内PP熔体的三维等温流场,采用粒子示踪分析法(PTA)分析了不同螺纹元件流道内粒子的拉伸度自然对数、分离尺度和停留时间,比较了常规螺纹元件和开槽螺纹元件的混炼效果。研究表明,与常规螺纹元件相比,由于熔体在沟槽内产生漏流,开槽螺纹元件的建压输送能力较低,分散混合性能较弱;开槽螺纹元件流道内因粒子的停留时间较长,其分布混合性能优于常规螺纹元件。     

专利文摘

块状橡胶连续塑炼的双转子结构及采用该转子的塑炼设备块状橡胶连续塑炼双转子结构,加料段是大导程螺纹元件,塑炼段分塑炼螺纹元件、螺纹开槽螺纹元件和机筒销钉螺纹元件。采用本发明双转子结构的塑炼设备的加料机构连通机     

啮合同向双螺杆挤出机普通螺纹元件中物料停留时间计算

采用有限元方法对啮合同向双螺杆挤出机的普通螺纹元件流动进行了三维等温非牛顿模拟计算，根据流场计算所得到的速度场通过编程计算得到了物料在螺纹元件中的三维流动路径，利用物料的三维流动路径计算结果分析了普通螺纹元件中物料的停留时间分布和平均停留时间随螺杆转速和挤出机产量的变化规律。     

组合式同向旋转双螺杆特性曲线分析

应用有限元分析软件ANSYS对同向旋转双螺杆挤出机螺纹输送元件中的三维非牛顿流动进行了模拟，计算出在一定转速和挤出量等工艺条件下螺纹元件的建压能力，确立了一定导程螺纹元件的特性曲线。在此基础上，对组合式同向旋转双螺杆挤出机工作特性进行了分析，并对双螺杆计量段充满长度和排气段脱挥长度的确定作了初步探讨。     

新型同向双螺杆元件——S型元件研究（Ⅰ）——流场数值模拟

对一种作者设计的新型同向双螺杆元件－S元件进行了流场计算。建立了三维非牛顿等温流场模型。利用ANSYS软件和自行编程计算了元件流场中的压力场，挤出量，回流量，速度场，剪切速率和拉伸速度，并对S形元件的流场与常规螺纹元件的流场作了一定的比较。在后续的文章中将对S形元件的流场及常规螺纹元件的流场计算结果进行实验验证。     

数值模拟研究螺纹元件的混合性能

使用FEM方法数值模拟了同向双螺杆螺纹混合元件和普通螺纹元件流道中硬聚氯乙烯的流动过程,计算了2种螺纹元件流道内熔体的非等温流场,使用粒子示踪法统计分析了2种螺纹元件流道内熔体的混合性能.研究结果表明,螺纹混合元件具有较均匀的剪切速率分布、较平缓的温度分布和较强的分散与分布混合能力,但是其输送能力较小.     

锥形双螺杆挤出过程菠萝型混合元件三维流场分析(Ⅰ)

应用ANSYS有限元软件对锥形双螺杆菠萝型混合元件进行了三维等温非牛顿流场的模拟分析 ,并与常规螺纹元件的流场分析结果进行了对比 ,得出了菠萝型混合元件比常规螺纹元件生产率高 ,分布混合能力强 ,其分散混合能力稍弱于常规螺纹元件的结论     

同向啮合双螺杆固体输送特性的可视化研究——螺纹元件的粉料输送

利用可视化的啮合同向双螺杆实验挤出机，对挤出过程中不同操作条件下粉状聚合物在螺纹元件中的输送特点、输送机理和输送能力进行了实验研究，并对不同导程的螺纹元件组合在计量和溢流加料时的输送能力进行了分析。     

Single screw extruders

The single screw extruder can offer a number of advantages over other continuous mixing systems such as lower costs, less maintenance and simpler operation. Pigments and additives can now be incorporated into resins to give compounds that may have filler loadings of up to 50%. New developments are now solving limitations in output, product uniformity and control. Plastics Additives & Compounding takes a look at some of the single screw extruders on the market     

挤出机螺杆断裂故障原因剖析

挤出机螺杆很少出现断裂的情况,即使是那些直径小于2英寸的螺杆也如此。但是不可否认,挤出机螺杆还是有发生断裂故障的情况,这是什么原因造成的呢？人们首先推测到的可能是由于扭矩过载而造成螺杆断裂,但是在现实中,造成螺杆断裂的往往不是扭矩过载,更多的是螺杆和机筒磨损所致。     

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     

Surging in screw extruders

Output uniformity is one of the main factors limiting the maximum output obtainable from a single screw plasticating extruder, and is adversely affected by surging. Several causes of surging have been identified, perhaps the most important being instabilities in the melting process. These are caused by periodic break-up of the bed of compacted solid polymer formed in the screw channel. Solid bed break-up is shown, both experimentally and theoretically, to be associated with rapid acceleration of the bed in the downstream direction parallel to the screw flight. A novel method of measuring solid bed velocity and hence acceleration is described. The theoretical model of the melting process is shown to be capable of predicting this acceleration reliably, and therefore the tendency for a particular combination of screw design, material and operating conditions to cause surging.     

三螺杆塑炼机

介绍了作者新研究开发的三螺杆挤出技术及装备。新技术利用倒品字型排列的全啮合三螺杆所构成的三个啮合区，实现对物料高效的塑炼作用。     

屏障型螺杆的变革

塑料加工中,挤出机机筒内膛不管是光滑式还是沟槽式都可以采用屏障型螺杆与之相配套使用。现今,屏障型螺杆的使用是一种行之有效的方法。然而屏障型螺杆的发展已经存在一个渐进地变化,从应用于欧洲市场的早期Maillefer设计即交替屏障型螺杆设计(图1),到Dray/Lawrence设计即采用并行的屏障型螺杆设计,该螺杆设     

螺杆冷却时单螺杆挤出熔融的可视化研究

利用可视化单螺杆挤出机,对螺杆冷却情况下的单螺杆挤出熔融机理进行了研究。实验表明,冷却螺杆时固体床始终保持连续而不破碎,有利于稳定的挤出过程。在熔融过程中．螺槽底部的表面靠近固体床的地方有一层半透明的物质．这种物质的产生与聚合物的亚稳态相转变行为有关.     

The effect of screw geometry on melt temperature profile in single screw extrusion

Experimental observations of melt temperature profiles and melting performance of extruder screws are reported. A novel temperature sensor consisting of a grid of thermocouple junctions was used to take multiple temperature readings in real time across melt flow in a single screw extruder. Melt pressure in the die and power consumption were also monitored. Three extruder screws at a range of screw speeds were examined for a commercial grade of low density polyethylene. Results showed melt temperature fields at low throughputs to be relatively independent of screw geometry with a flat‐shaped temperature profile dominated by conduction. At high throughputs, melting performance and measured temperature fields were highly dependent upon screw geometry. A barrier‐flighted screw with Maddock mixer achieved significantly better melting than single flighted screws. Low temperature “shoulder” regions were observed in the temperature profiles of single‐flighted screws at high throughput, due to late melting of the solid bed. Stability of the melt flow was also dependent upon screw geometry and the barrier‐flighted screw achieving flow with lower variation in melt pressure and temperature. Dimensionless numbers were used to analyze the relative importance of conduction, convection, and viscous shear to the state of the melt at a range of extrusion conditions. Polym. Eng. Sci. 46:1706–1714, 2006. © 2006 Society of Plastics Engineers     

新型螺杆元件对LDPE-g-MAH反应挤出的影响

改变同向双螺杆挤出机主反应区的螺杆元件,研究该螺杆元件对低密度聚乙烯(LDPE)熔融接枝马来酸酐(MAH)的接枝产物和接枝率的影响。傅里叶变换红外光谱分析证实,部分MAH成功接枝到LDPE分子链上。对挤出沿程4个在线取样位置的试样做了对比分析,结果表明具有高剪切性能的捏合盘元件的沿程试样接枝率最大,熔体流动速率最小;具有高分布混合性能的齿形盘元件的沿程试样接枝率较大,熔体流动速率较小;具有回混作用的非啮合多过程元件能够迅速提高该元件所在区域的接枝率。