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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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单螺杆挤出机固体输送机理研究的发展与趋势 总被引:1,自引:0,他引:1
介绍了国内外单螺杆塑料挤出机固体输送理论研究的发展,指出对固体输送段中固体颗粒体系密度和磨擦系数的研究是固体输送理论的两个研究热点,因为它们为更好地预测固体输送段的压力、产量提供数据,并指导团体输送段的设计及工艺操作。还提出了将固体输送与熔融过程作为一连续过程来研究的思路。 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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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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新型螺杆挤出机固体输送理论的研究 总被引:4,自引:0,他引:4
介绍了一种嵌套式新型螺杆挤出机。在固体输送段对内螺杆的两种等效情况下固体塞的运动和受力作了深入分析。理论上证明了这两种情况下的固体输送机理与外螺杆的情况相同,均建立在固体摩擦输送机理基础之上;讨论了牵引角、摩擦因数和螺纹升角对上述三种情况固体输送流率的影响。结果表明,螺杆旋转机筒静止和螺杆静止机筒旋转两种情况下固体输送流率相差不大,而螺杆机筒同时旋转情况下的固体输送流率远大于其他两种情况。增大牵引角、降低螺杆表面粗糙度和提高机筒内表面的摩擦因数均有助于提高固体输送流率。螺杆旋转机筒静止和螺杆静止机筒旋转这两种情况下最佳螺旋角均为17°左右,而螺杆机筒同时旋转情况下最佳螺旋角为15°左右。 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
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A theoretical model was developed for the newly-defined delay zone of the plasticating screw extruder. The delay zone starts at the end of the solids conveying zone, i.e. at the point where the solid plug surface contacting the barrel melts and forms a film of melt up to where the steady state melting mechanism starts to operate. The model permits the film thickness and pressure profiles in this zone to be calculated. Published results were used to support the validity of the model. The results indicate that the film thickness at the end of the delay zone is several times the flight clearance. Finally, a criteria, based on the final value of the film thickness, is suggested to calculate the length of the delay zone. 相似文献
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单螺杆挤出过程固体输送段的数值模拟 总被引:4,自引:0,他引:4
介绍了挤出成型过程数值模拟的现状及现有通用计算流体力学(CFD)软件在模拟聚合物流动时存在的缺陷,指出自主开发CFD程序的必要性。针对单螺杆挤出过程固体输送段的数值模拟方法,讨论了传统塞流固体输送理论的缺陷,介绍了非塞流固体输送理论的优越性及相关的有限元计算方法。并针对有限元方法的复杂性,介绍了简化的三层模型方法。计算结果表明:非塞流固体输送理论的三层模型法与有限元法计算结果接近,且优于塞流固体输送理论,而三层模型法计算方法简单,便于其在工程计算中的应用。 相似文献
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A novel melting model for single screw extruders with a grooved melting zone was established. The whole solid plug, which came from the grooved feed zone, was ruptured and melted mainly by continuously changing the volume of the barrel grooves and the screw channel in the grooved melting zone. A new single screw extruder platform with hydraulic clamshell barrels was constructed to investigate the melting of solid polymer with different combinations of barrels and screws. The melting model was verified by experiments. The results showed that the melting started earlier and finished in a shorter length for single screw extruders with a grooved melting zone than that for conventional single screw extruders and the melting efficiency was improved by introducing a grooved melting zone to a single screw extruder. The theoretical values are consistent with experimental results. The novel single screw extruder with grooved melting zone can dramatically increase the plasticizing efficiency and the throughput. 相似文献