橡胶在销钉机筒挤出机中的流动模拟

在销钉机铜挤出机上,建立非牛顿流体的流动模型,计算出压力场、流动场和 杆的特性曲线。随着非牛顿特性的降低,螺杆的生产能力减少。随着螺杆上切口的增多,在螺杆切槽内的逆流增加,而产量也减少。机筒上的销钉对挤出特性影响力很小。销钉机筒挤出特性与螺杆上切口的挤出机的挤出特性非常相似。     

对销钉机筒挤出机胶料挤出的基本研究（译文）

使用三种不同的橡胶－炭黑胶料在一台模型销钉机筒挤出机上进行实验，对胶料的流动、推进和混合特性进行研究，三种胶料分别是ＳＢＲ／ＢＲ（丁苯橡胶／丁二烯橡胶）乘用轮胎胶料，ＮＲ（天然橡胶）载重轮胎胶料和ＮＢＲ（丁腈橡胶）工业制品胶料。实验对螺杆上没有销钉或挡板／沟槽的普通挤出机，螺杆上有挡板或沟槽的挤出机以及销钉机筒挤出机分别进行了对比．发现在螺杆上增加挡板可改善胶料的混合／均匀性，但同时会降低胶料的推进能力：采用销钉则既可改善混合／均匀性又不会影响推进力。均匀性最好的是乘用胎胎面胶料，均匀性最差的是ＮＢＲ工业制品胶料。     

销钉机筒单螺杆挤出机功耗的模拟研究

采用流体力学计算软件Fluent，在对销钉机筒冷喂料挤出机熔融段和计量段的胶料进行三维流动数值模拟的基础上，考察螺杆转速、反向压差、销钉数量、销钉排间距和螺槽深度对挤出量和螺杆转矩的影响。结果表明，螺杆转速是影响挤出机功耗的首要因素，随着转速增大，挤出量增大，功耗和功耗比（螺杆转矩与挤出量之比）下降；反向压差对挤出量、螺杆转矩和功耗比有一定影响，反向压差越大，功耗比越大；每排销钉数量对对功耗比影响不大；销钉排间距对挤出机功耗比有较为明显的影响，若只考虑产量和功耗，则销钉排间距越大越好。     

国外橡胶挤出理论研究简介

概述了近年来国外有关橡胶挤出理论的研究情况。介绍了普通型、强力剪切型、销钉机筒型及传递型橡胶冷喂料挤出机螺杆螺槽内胶料流动特性理论研究的动向。     

冷喂料销钉挤出机非等温流动过程的模拟

销钉挤出机在橡胶工业上起着重要的作用。本文给出了销钉挤出机内物料的流动和生热量的模型。这模拟模型是以流体动力润滑理论为基础的,并且运用了修正过的流动网络分析(FAN)数值分析技术。本方法创新之处在于它考虑了由粘流引起热分散对热传导的影响以及在与FAN技术等同的精确度上热的转换。这一方法已用于计算螺杆挤出机内牛顿流体的压力场,速度场和温度场。我们研究了粘性流体生热对销钉机筒内螺杆推进特性的影响。随着温度对粘度依赖性的增加,销钉挤出机的物料传递能力下降。本文也考虑了销钉对热特性的影响。     

切向销钉式挤出机

德国Colmec公司生产的享有专利权的切向销钉式挤出机（TPT），其螺杆直径要比光滑机筒的常用挤出机长40％。该机的特殊标志是设有销钉，而这些销钉在挤出机筒上呈径向排列，可提高挤出机的生产能力并阻止胶料回流。     

橡胶销钉机筒冷喂料挤出机的开发

橡胶销钉机筒冷喂料挤出机的开发魏新利，谢本万（郑州工学院４５０００２）１销河机筒冷暖料挤出机的特点销钉机筒冷喂料挤出机是７０年代中期国际上出现的新一代冷喂料挤出机。其特点是在机筒上安装６—１６排、每排６—１２校销钉，销钉穿过机筒朝螺杆中心呈辐射状固定...     

市场动态

切向销钉挤出机问世 意大利科美高公司开发的新型切向销钉挤出机,其销钉(杆)从方形机筒插入后与螺杆相切,销钉杆中设有冷却介质通道,而传统的销钉挤出机中销钉是沿机筒周向均匀布置,向内插入螺杆的螺槽根部。 由于新型挤出机的销钉与胶料直接接触的长度比传统挤出机更长,因此对胶料的剪切作用更多。同时,由于销钉     

销钉机筒挤出机塑化段传热温度模型研究

通过建立简化的销钉机筒挤出机塑化段物理模型，从流变分析中的能量方程出发，导出销钉机筒挤出机塑化段温度的传热模型；结合试验数据，拟合出挤出温度随螺杆转速变化的曲线。结果表明，曲线可分为急速增长段、平缓增长段和稳定增长段3部分，且平缓增长段是挤出温度、质量和能耗综合指标最佳的区间。     

一种新冷喂料销钉式挤出机

美国RMS公司的PME冷喂料销钉式挤出机是供加工橡胶胶料使用的。该冷喂料销钉式挤出机的设计准则包括：机筒销钉插入于螺杆螺纹槽内以破碎和混匀胶料；在该机筒内部有可替换的增强村层；带有喂料辊的高进料料斗能保证连续向该机喂入胶片或胶条；在上述料斗，机筒和螺杆内部的加热和冷却通路使之具有温度有序分布的特性；胶料的良好混合能在低于一般加工温度下提高挤出率等。此外，该公司声称所用螺杆是以美国钢铁学会（AISI）4150的主材料加以制作的，而上述高位料斗是装在齿轮减速箱与销钉机筒之间的钢组合件总成。再之，宽敞的料斗目能…     

销钉机筒挤出机内销钉附近物料流场分析及功率计算

采用当量粘度的方法，基于牛顿流体模型，提出销钉机筒挤出机内销钉附近流场的应力及速度分布数学模型和销钉消耗功率的计算方法。用NR／炭黑混炼胶进行的挤出过程中销钉消耗功率的研究结果表明，实测值与计算值的相对误差只有4％。     

Finite element modeling of the flow of a rubber compound through an axisymmetric die using the CEF viscoelastic constitutive equation

This work is devoted to the simulation of the flow of a high viscosity NR/SBR rubber compound through the die of a single screw extruder with axisymmetric geometry. An in-house developed computer code based on the use of continuous penalty finite element method was employed. Three constitutive equations including two generalized Newtonian models namely; power-law and Carreau and an explicit viscoelastic model named CEF (Criminale-Ericksen-Fillbey) were used to reflect the rheological behavior of the material. Using the parameters of the rheological models determined by a slit die rheometry technique, the flow of the compound was simulated through the die and results were compared with experimentally measured mass flow rates. It is shown that for high viscosity rubber compounds the use of generalized Newtonian models which do not take the normal stress in simple shear flow into consideration gives rise to significant errors in prediction of mass flow rates. On the other hand, comparing the simulations results using the CEF equation with experimental data revealed that this model is the best compromise between generalized Newtonian and full viscoelastic models which need high computational costs and effort. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

挤出机螺杆计量段的优化设计

讨论了挤出机螺杆计量段的优化设计问题。应用粘性流体动力学基本方程，分析了聚合物物料在螺槽中的流动。以单位产量能耗最小为优化目标，建立简化的挤出机计量段螺杆优化设计的数学模型，应用约束随机方向法求解。结果表明，螺槽深度、螺纹棱顶宽度、螺纹棱顶与机筒间隙和螺纹升角均位于或接近于献中所建议的最佳取值范围。     

Steady and transient flow of a non‐Newtonian chemically reactive fluid in a twin‐screw extruder

The flow of chemically reactive non‐Newtonian materials, such as bio‐polymers and acrylates, in a fully intermeshing, co‐rotating twin‐screw extruder is numerically investigated. A detailed study of the system transient behavior is carried out. The main transient aspects, including response time, variation of system variables, and instability of operation, are studied for both single‐ and twin‐screw extruders, since single‐screw extruder modeling closely approximates the region away from the intermeshing zone in a twin‐screw extruder. The effect of a time‐dependent variation in the boundary conditions is studied. The coupling due to conduction heat transfer in the screw barrel is found to be very important and is taken into account for single‐screw extruders. In the absence of this conjugate coupling, the response time is much shorter. Several other interesting trends are obtained with respect to the dependence of the transient response on the materials and operating conditions. Steady state results are obtained at large time. The calculated velocity distributions in the screw channel are compared with experimental results in the literature for steady state flow and good agreement has been obtained. The calculated results for transient transport agree with the few experimental observations available on this system. Chemical reaction, leading to chemical conversion of the material, is also considered and the resulting effects on the flow and transport determined. These results will be useful in the design, control and optimization of polymer extrusion processes.     

橡胶挤出成型技术的最新进展

简要介绍了销钉式冷喂料挤出机、双螺杆连续混炼、销钉式冷喂料挤出机及新型胶片挤出成型机组等几种新型挤出成型技术,并将传统工艺与新工艺进行了对比。     

Infrared melt temperature measurement of single screw extrusion

An infrared temperature sensor has been used to provide real time quantification of the thermal homogeneity of polymer extrusion. The non‐intrusive sensor was located in the barrel of a single screw extruder, positioned such that it provided a measurement of melt temperature in the channel of the metering section of the extruder screw. The rapid response of the technique enabled melt temperature within the extruder screw channel to be monitored in real time, allowing quantification of the thermal stability of the extrusion process. Two polyethylenes were used in experiments with three extruder screw geometries at a range of screw speeds. Data generated by the infrared sensor was found to be highly sensitive to thermal fluctuations relating to the melting performance of the extruder screw. Comparisons made with an intrusive thermocouple grid sensor located in the extruder die suggested that the infrared technique was able to provide a similar level of information without disturbing the process flow. This application on infrared thermometry could prove highly useful for industrial extrusion process monitoring and optimization. POLYM. ENG. SCI., 55:1059–1066, 2015. © 2014 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers     

Numerical analysis of a reactive extrusion process. Part II: Simulations and verifications for the twin screw extrusion

A newly designed extruder reactor for grafting vinyl monomers onto polyolefins was studied experimentally and theoretically. The process was made up of a self‐wiping co‐rotating twin screw extruder with a separated reaction zone and two vent zones. The reactive extrusion was performed using a linear low density polyethylene, vinyltrimethoxysilane and di‐t‐butylperoxide under different operation conditions. For the purpose of process analysis, we built a computer simulation based on the reaction kinetics and rheological models studied in the preceding paper. The flow field in the extruder was calculated by the flow analysis network (FAN) method with non‐isothermal non‐Newtonian flow conditions. The iterative procedure was organized to predict local pressure, filling factor, cumulative residence time and temperature along the extruder. Furthermore, we succeeded in representing the profiles of reaction conversion and shear viscosity. Calculated results showed good agreements with the experimental data.     

A die rotating system for moderations of extrusion load and pressure drop profiles for molten PP and wood/polypropylene composites in extrusion processes

A die‐rotating system was proposed in this work for moderations of extrusion forces and entrance pressure drop for molten polypropylene (PP) and wood/polypropylene (WPP) composites in a capillary rheometer and a single screw extruder. The effects of processing conditions and wood loading in PP were of our interests. The extrusion force and entrance pressure drop with and without the die rotating system were monitored in real‐time. This was the first time that the die‐rotating system was used for processing of highly viscous wood/polymer composite materials. It was found that the flow properties of the molten PP and WPP composites obeyed pseudoplastic non‐Newtonian behavior. The behavior was more obvious at wood contents of above 6 wt % and in the capillary rheometer. The rotation of the die could moderate the extrusion load by 60% and entrance pressure drop by 20% in the capillary rheometer, and the entrance pressure drop by 30% in the single screw extruder, especially at the conditions where the viscosities of the WPP and the extrusion rate were high. Greater fluctuations in entrance pressure drop caused by die rotation were observed in the single screw extruder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120:1006–1016, 2011