共查询到17条相似文献,搜索用时 203 毫秒
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新型螺杆挤出机熔体输送理论的研究 总被引:1,自引:0,他引:1
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。 相似文献
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螺旋沟槽单螺杆挤出机双螺棱推动理论模型的研究 总被引:2,自引:0,他引:2
潘龙;贾明印;薛平;金志明;唐广利 《中国塑料》2010,24(11):94-99
通过在单螺杆挤出机固体输送段机筒内壁开设螺旋沟槽,建立了将机筒与螺杆视为一个对物料协同作用的整体的新型物理模型——弧板模型;同时将嵌入机筒沟槽与螺杆螺槽中的物料视为固体塞,提出了新型"双螺棱推动理论",弥补了单螺杆挤出机不能实现正位移输送的传统理论缺陷;最后,通过理论分析确定了螺旋沟槽挤出机由摩擦拖曳输送向正位移输送转换的边界条件方程及正位移输送下沟槽结构参数的设计准则。 相似文献
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在分析机筒衬套沟槽槽深、螺杆螺槽槽深和加工物料粒径关系的基础上,建立了沟槽机筒单螺杆挤出机3种常见的固体输送段产量粒径模型,该模型可用于研究机筒衬套沟槽槽深、螺杆螺槽槽深和颗粒物料粒径对固体输送机理的影响并定量计算沟槽机筒单螺杆挤出机固体输送段产量。此外,通过不同的机筒和螺杆组合及不同粒径的原料在自制的在线模拟试验机上对该模型进行了验证和试验分析。 相似文献
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强制加料挤出机的出料计算 总被引:1,自引:0,他引:1
本文介绍了开槽机筒挤出机的强制加料机理,分析了开槽区固体物料与机筒之间的摩擦类型以及挤出特性,阐述了在强制输送和与背压相关两种情形下的挤出量计算。对强制加料挤出机的设计,研究及应用均具有参考价值。 相似文献
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离心式挤出机是一种新型的塑料加工机械,具有节能特点。详细地介绍了离心式挤出机的结构及工作原理。根据离心式挤出机的固体输送机理建立固体输送压力分布的数值模型,并研究分析了转鼓结构(半径、锥角)、转鼓内壁与聚合物之间的摩擦因数、以及转鼓转速对固体输送压力分布的影响。 相似文献
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On the basis of the theory of relative motions, a novel nested screw extruder was invented in which one rotating outer screw acted as the barrel for an inner screw; the combination of the outer screw and outer barrel was the other extrusion system. It was realized that centrifugal force resulted in the difference between the forces acting on the solids by the screw and by the barrel, which further compacted the solid pellet or powder. These factors benefited the frictional drag of solids and the early melting. This was consistent with the fact that the solids conveying flow rate increased greatly when the barrel and screw rotated oppositely at the same time. Thus, centrifugal force and material compressibility were significant in the feeding zone. A mathematical model was developed to calculate the output, pressure, and velocity of the solids in the screw down‐channel with consideration of the centrifugal force and material compressibility. The predicted pressure distribution and output were better than those by previous models in fitting the experimental data. The simulations revealed that the maximum traction angle was close to 90° ? the helix angle for maximum output in contrast to the maximum traction angle of 90° predicted by the Darnell–Mol theory. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
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Studies on the theory of single screw plasticating extrusion. Part II: Non-plug flow solid conveying
A non-plug solid conveying theory for plasticating extrusion is proposed in this paper. The polymer granules are treated as-bulk pellets which move down the screw channel at different speeds, rather than as a plug which never experiences deformation during extrusion. The pellets system is considered as a linear elastic system, and can only resist compressive forces but riot tensile forces. Based on elastic mechanics and virtual work principles, a mathematical model for non-plug solid conveying is proposed. Finite element method (FEM) is used to determine the relationships between internal stress and velocity profiles of the pellets in the screw channel, the internal stress states at any point in the screw channel, etc. The prediction also proved the existence of the optimum depth of the screw channel and the optimum helix angle of the screw. Most of the experiments have been carried out on an extruder with glass windows it its barrel. The experiments confirm the validity of the theory. 相似文献
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单螺杆挤出固体输送段非塞流的三层模型法 总被引:7,自引:0,他引:7
依据单螺杆挤出机固体输送段的非塞流现象,把固体塞分成上、中、下三层,通过应力—速度方程,推导出产量与压力降的三次方程;详细讨论了摩擦系数对最大产量的影响,并深入地分析了单螺杆挤出机固体输送段产量与末端压力的关系,通过这些分析计算,三层模型法能很好地预示单螺杆挤出机固体输送段的压力与产量,该方法不仅简单明晰而且精度高,是一个可使用的方法 相似文献
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Manuel Längauer Keyan Liu Christian Kneidinger Gernot Schaffler Bianca Purgleitner Gernot Zitzenbacher 《应用聚合物科学杂志》2015,132(13)
Extrusion technology is one of the most prominent methods for processing polymers. The shape of polymer pellets plays an important role in conveying solid material through the extruder and thus directly influences the mass flow rate. In the course of this article, the influence of the pellet shape of a polypropylene homopolymer on the processing conditions using a smooth barrel single‐screw extruder is evaluated. Especially the mass flow rate, the melt temperature, and the pressure build up in the barrel are investigated. It can be shown that processing long cylindrical pellets leads to a higher mass flow rate than comparable experiments with virgin pellets or short cylinders. Additionally, screw cool and pull‐out tests, measurements of the external coefficient of friction as well as the bulk density of the different pellet geometries are performed. The interaction of the screw geometry and the pellet shape is found to have the biggest influence. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41716. 相似文献
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注塑机螺杆的固体流变分析 总被引:1,自引:0,他引:1
分析了注塑机螺杆工作时加料段塑料颗粒的流动特性,介绍了塞流固体输送理论及非塞流固体输送理论的基本计算方法,并引入压力的计算公式,从而使塞流固体输送流率可直接计算求解。 相似文献
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Isothermal solids conveying theories have been developed in the past. However, due to friction, the surface temperature of the solid plug does increase. This change in temperature will strongly affect the temperature sensitive coefficients of friction and consequently also the pressure that develops. The surface temperature of the solid plug is also an important variable on its own because, when it reaches the melting point, the solids conveying zone is terminated. A mathematical model has been developed to calculate the temperature profile in the solid plug together with the strongly interacting pressure profile. Calculations indicate that high pressure in the solids conveying zone can practically be obtained only by very efficient cooling of the barrel in this zone. 相似文献
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An improved theoretical model was derived for the solids conveying zone of a plasticating extruder. The model makes possible calculations in variable channel depth section. It also allows for a bulk density which is a function of pressure and for the non-isotropic pressure distribution in the solid plug. An expression for maximum flow rate was also derived. Results simulated by the model on a computer indicate the effect of variables on extruder performance. The power consumption terms in the solids conveying zone of a plasticating extruder were also derived. Total power consumption is the sum of power consumptions on the barrel surface, screw surfaces and those due to pressure rise. Their relative importance was analyzed by computations. The effect of operating conditions and coefficients of friction on the various power terms was also analyzed. 相似文献