行星螺杆挤出机结构参数对加工性能影响的实验研究

利用自行开发的行星螺杆挤出机实验装置,研究了不同的口模直径、行星螺杆数量等结构参数对行星螺杆挤出机的机头压力、熔体温度、物料最短停留时间和功耗等的影响。     

行星螺杆挤出机的发展

介绍了行星螺杆挤出机(PRE)的优点,从理论研究、结构改进和应用发展3个方面总结了行星螺杆挤出机近年来取得的新进展。目前行星螺杆挤出机的理论研究集中在对主要参数的计算和塑化效果的研究;结构方面的改进包括增加行星段的长度,行星螺杆挤出机与不同的挤出设备组合等;同时行星螺杆挤出机的应用范围则扩大到木塑复合材料、聚对苯二甲酸乙二醇酯(PET)加工、硅橡胶、食品加工等领域。     

新型橡胶螺杆挤出机及其应用

介绍橡胶工业新型螺杆挤出机的结构和应用范围。广泛应用的新型橡胶挤出机有同向双螺杆挤出机、异向双螺杆挤出机、多螺杆挤出机和行星挤出机等。同向双螺杆挤出机主要用于物理改性如共混、填充、纤维增强等；异向双螺杆挤出机主要用于挤出成型；多螺杆挤出机主要用于连续橡胶混炼，行星挤出机则更易控制加工温度。     

行星-单螺杆一体化挤出机流场数值模拟及单螺杆参数对流场的影响(Ⅱ)

根据计算流体动力学(CFD)理论,采用Polyflow软件对行星-单螺杆一体化挤出机的流场进行了数值模拟。通过综合运用正交试验法(见"行星-单螺杆一体化挤出机流场数值模拟及单螺杆参数对流场的影响(I)")与单因素分析法,重点分析了螺杆直径、导程、螺纹断面形状、锥度角等单螺杆结构参数对行星-单螺杆一体化挤出机建压能力的影响。该研究对行星-单螺杆一体化挤出机的设计开发和挤出工艺的优化具有一定指导意义。     

行星-单螺杆一体化挤出机流场数值模拟及单螺杆参数对流场的影响(Ⅰ)

根据计算流体动力学(CFD)理论,采用Polyflow软件对行星-单螺杆一体化挤出机的流场进行了数值模拟。通过综合运用正交试验法与单因素分析法(见"行星-单螺杆一体化挤出机流场数值模拟及单螺杆参数对流场的影响(II)"),重点分析了螺杆直径、导程、螺纹断面形状、锥度角等单螺杆结构参数对行星-单螺杆一体化挤出机建压能力的影响。该研究对行星-单螺杆一体化挤出机的设计开发和挤出工艺的优化具有一定指导意义。     

一种新型嵌入式行星螺杆挤出机及其混沌混合行为

提出了一种新型嵌入式行星螺杆挤出机结构,引入了周期性扰动及排气功能,研制成功1.5代实验样机。对嵌入式行星螺杆内流动与混合开展了数值模拟研究,初步进行了线性低密度聚乙烯填充10%CaCO3挤出样品扫描电子显微镜测试,并与同向双螺杆挤出机挤出样品进行了对比分析。证实了行星螺杆的周期性扰动可以导致混沌混合的发生,有利于螺杆压力的建立、能有效提高物料分散混合效果和提高制品质量。     

国外橡胶工业新型螺杆挤出机及其使用范围

近10年来，随着橡胶制品向高品质、高性能、多样化和低成本化方向发展，相应开发了多种高性能橡胶挤出机以适应生产需要。橡胶制品行业广泛应用的除销钉冷喂料挤出机外，还有同向双螺杆挤出机、异向双螺杆挤出机、多螺杆挤出机和行星挤出机等。     

橡胶冷喂料挤出机螺杆结构几何参数分析与选择

螺杆是挤出机的核心部件,而螺杆又是由众多的结构几何参数所组成。因此螺杆几何参数的确定和选择直接关系着挤出机的使用性能。本文分析了螺杆几何参数影响挤出过程的理论依据,进而对各几何参数进行选择和确定,为螺杆和挤出机的设计、选型提供依据和参考。     

排气挤出机排气原理及排气效率研究

本文分析了排气挤出机排气段的功能和排气原理，指出在设计排气挤出机螺杆各段结构参数时，必须综合考虑螺杆各段结构参数。文中还分析了排气口位置，螺杆结构和工艺参数等对气挤出机效率的影响，并进行了实验验证。     

新型偏心三螺杆挤出机流体混合特性分析

在传统的三螺杆挤出机的基础上,设计了一种新型偏心三螺杆挤出机。该三螺杆挤出机中具有螺杆几何结构偏心、螺槽构型呈梯度变化特殊以及较高的面积利用系数等特征。利用有限元法对聚丙烯（PP）熔体在新型偏心三螺杆挤出机中流动和混合规律进行三维数值模拟,给出偏心三螺杆挤出机中压力和速度分布规律,计算了3种偏心螺杆挤出流场的停留时间分布、分布指数、分离尺度、最大剪切应力等混合表征参数。结果表明,螺杆偏心距不仅决定了螺杆端面形状,也改变了螺槽梯度的变化程度。随着螺槽梯度的逐渐减小,挤出机内粒子团聚效应逐渐降低、物料剪切作用逐渐增强。在3种新型偏心三螺杆挤出机中,偏心距e=3 mm的新型偏心螺杆挤出机的混合性能相对较好。     

单螺杆挤出机螺旋沟槽固体段产量的实验研究

在自制的测试仪上对单螺杆挤出机螺旋沟槽固体输送段的产量进行了实验研究,探讨了沟槽衬套、螺杆的结构参数,物料粒径大小及螺杆转速对单螺杆挤出机固体输送段产量的影响,同时将螺旋沟槽单螺杆挤出机与IKV挤出机固体输送段的产量进行了对比。实验研究表明：粒径越小,螺旋衬套沟槽越宽,固体输送段产量越高;螺杆螺距变化对挤出机固体输送段产量的影响很小;IKV直槽挤出机固体输送段的产量明显小于螺旋沟槽衬套挤出机的固体输送产量,而且随着转速的增加,趋势越明显。     

行星螺杆挤出机实践

介绍了行星螺杆挤出机设计，制造中一些重要技术参数的确定以及实践中一些有益尝试。     

单螺杆挤出机螺旋沟槽固体段压力的实验研究

在自制的压力测试仪上对单螺杆挤出机螺旋沟槽固体输送段的压力进行了实验研究,探讨了螺杆转速,沟槽衬套、螺杆的主要结构参数以及物料的粒径大小对挤出机固体输送段压力的影响,同时将螺旋沟槽单螺杆挤出机与IKV挤出机固体输送段的建压能力做了对比.实验研究表明:螺杆转速、沟槽宽度对固体输送段压力影响较小;粒径越小,螺杆螺距越大,挤...     

同向旋转三螺杆挤出机固体输送段输送特性研究

基于离散元法分别对同向旋转的三螺杆以及双螺杆挤出机固体输送行为进行仿真模拟,对三螺杆挤出机颗粒速度分布以及受力分布进行分析,将三螺杆和双螺杆挤出机颗粒填充效率、输送质量以及质量流率进行对比分析.结果表明,位于螺棱和机筒附近位置的颗粒受到螺棱推力及机筒摩擦力影响较大,具有较高的速度;挤出机内部各区域颗粒填充顺序受螺杆旋转...     

Residence time distribution in a real single screw extruder

The residence time distribution in an industrial single screw extruder was investigated experimentally in the case of melt and plasticating extrusion. The investigations performed proved that the extrusion parameters influence strongly the residence time distribution in the extruder. It was found that the resistance to flow through the die-head of the extruder is very important from this point of view, as well as other parameters like rotational speed of the screw and the screw channel depth. Variation of these parameters can change the residence time distribution over a broad range between the extreme idealized cases of plug flow and flow with perfect mixing. In order to obtain quantitative dependences three moduli were used and a correlation equation was obtained. This equation enables an estimation of residence time distribution on the basis of experimental characteristics of the extruder and the actual extrusion parameters.     

Free radical grafting of glycidyl methacrylate onto polypropylene in a co-rotating twin screw extruder

Free radical grafting of glycidyl methacrylate (GMA) onto molten polypropylene (PP) was studied in a co-rotating twin screw extruder. Grafting yields of GMA obtained under various experimental conditions along the screw length allowed for a good appreciation of the effects of chemical parameters (the presence of styrene and the concentrations of peroxide and monomers) and those of processing parameters (feed rate, screw speed, and specific throughput). Similar to the results obtained in a batch mixer,¹ free radical grafting of GMA carried out in the extruder in the presence or absence of styrene proceeded rapidly, as it was virtually completed half-way down stream of the extruder. Additionally, the presence of styrene as a second monomer increased the GMA grafting yield reatly with reduced PP chain degradation. The ultimate GMA grafting yield increased with increasing concentration of peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene. This similarity between the batch mixer and the extruder is related to the fact that in both cases it is the concentration of the peroxide and its half lifetime that determine the grafting rate and the ultimate grafting yield. On the othe hand, the GMA grafting yield decreased with increasing screw speed or feed rate. For a particular specific throughput (the ratio of throughput to screw speed), an increase in throughput with a concomitant increase in screw speed brought about a decrease in GMA grafting yield. It was concluded that the GMA grafting yield is affected primarily by the residence time in the zone in which free radicals are not depleted. The effects of screw speed, feed rate, and specific throughput manifest mainly through this local residence time distribution. Specific energy is not a good measure of the performance of the extruder with respect to the free radical rafting of GMA onto PP. © 1995 John Wiley & Sons, Inc.     

Effects of Extruder Parameters and Compositions on Mechanical Properties and Morphology of Maleic Anhydride Grafted Polypropylene/Waste Tire Blends

A co-rotating twin screw extruder was used for blending thermoplastic elastomeric blends of ground rubber tire (GRT) and maleic anhydride grafted polypropylene (PP-g-MA). The dynamic reaction occurring between the blends necessitates a study of the processing parameters of the extruder. The effects of the extruder screw configurations, screw speed, compatabilizer and blend ratios on the mechanical properties, and morphology was studied. Out of the four different screw configurations A, B, C, and D, screw D with reverse flow elements was found to be highly efficient with respect to mechanical properties, particularly at 100 rpm screw speed. SEM studies revealed that GRT and PP-g-MA are thermodynamically miscible under optimized screw configuration and processing condition of 100 rpm screw speed. SEM studies also show that the addition of compatibilizer increases the miscibility and, consequently, the mechanical properties. Finally, a composition involving GRT/PP-g-MA/SEBS-g-MA as 65/35/10 by weight was found to be optimum.     

双螺杆挤出丁苯透明抗冲树脂溶液脱挥工艺

将质量分数为20．00％的丁苯透明抗冲树脂溶液经浓缩器提浓至质量分数不小于30．00％后,送入同向啮合式双螺杆挤出机,在多段真空状态下脱除溶剂,研究了双螺杆挤出脱挥工艺中的温度、真空度、停留时间和螺杆转速工艺务件,并与湿法凝聚工艺进行了产品分子参数和能耗对比。结果表明,双螺杆挤出脱除溶剂工艺适用于丁苯透明抗冲树脂溶液脱除溶剂,其能耗远低于湿法凝聚,所得产品的性能与国外同类产品基本相当。     

振动诱导单螺杆挤出机熔融过程实验研究

利用剖分式料筒振动诱导单螺杆挤出机以及透明料筒振动诱导单螺杆挤出机对振动力场作用下的熔融过程进行了可视化实验研究，获得了熔融过程的固体床宽度分布曲线；对比了不同振动参数条件下的熔融长度与无振动条件下的熔融长度。实验结果表明，振动的引入可加快熔融进程，缩短熔融长度。对应不同的材料，不同的螺杆转速、料筒温度设置等工艺条件存在一个振动强度范围，在此范围内随着振动强度的增加，熔融速度进一步加快。