共查询到19条相似文献,搜索用时 109 毫秒
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振动力场下聚合物塑化挤出技术研究 总被引:16,自引:3,他引:13
介绍玫种将电磁场引起的机械振动力场引入聚合物塑化挤出全过程的塑料电磁动态塑化挤出设备,讨论了它的原理、结构及应用,实验与生产表明,塑料电磁动态塑化挤出设备在加工聚烯烃时能耗降低20%~50%,挤出熔体温度降低20℃以上,制品拉伸强度提高16%以上,对无机填料充体系的兴旺聚散效果提高。 相似文献
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采用自行修正的Tanner本构方程,对塑料电磁动态塑化挤出机中挤出压力对振动力场的响应进行了研究,建立了振动力场下挤出压力响应的理论模型,分析了振动力场作用下挤出压力降低的原因,并从实验方面进行了验证,结果表明,理论分析的结论是基本合理的。 相似文献
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振动场强化聚合物塑化注射成型技术 总被引:7,自引:2,他引:5
介绍一种将机械振动力场引入聚合物塑化注射成型全过程的塑料电磁动态注射设备,提出振动力场强化聚合物塑化注射成型新概念,并论述塑料电磁动态塑化注射机的原理、结构及其应用.实验与生产表明:新型注射机对物料适应性广,与传统注射机比较在加工聚烯烃时能耗可降低50%以上,注射熔体温度可降低20℃以上,注射压力降低10%左右,制品力学性能提高15%以上,对无机填料填充体系的混合分散效果明显提高,并预示振动力场可改变注射充模熔体的流动状态.新型塑料注射机对聚合物加工工业的发展具有重大的科学和现实意义. 相似文献
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振动力场对m-PE-LLD薄膜拉伸强度的影响 总被引:1,自引:0,他引:1
使用电磁动态吹膜机组加工m-PE-LLD薄膜,将振动力场引入到塑化挤出的全过程,考察了振动力场对m-PE-LLD薄膜拉伸强度的影响。研究发现,振动力场的加入使m-PE-LLD吹塑薄膜的横向强度增大、纵向强度减小,纵、横向拉伸强度趋于均匀。振动力场对PE-LD和PE-HD的拉伸强度的影响具有相似的规律,初步的分析机理认为:振动力场引入后,聚合物熔体同时受到轴向和周向的作用力,分子链会沿两个作用力的方向进行排列,形成网格化排列的结构,从而使薄膜纵、横向强度趋于均一。 相似文献
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Quan Wang 《Polymer-Plastics Technology and Engineering》2013,52(11):1055-1061
In the reciprocating extrusion, the vibration force field (VFF) is applied to the entire plasticating process by the axial vibration of screw and the novel concept on the polymer dynamic plasticating process being strengthened has been brought forward in the paper. The mathematical model is established that describes the plasticating process under the VFF and the approximative analytical solutions of the velocity distribution, pressure gradient in the screw channel and the plasticating capability are obtained. The theoretical results show that the axial vibration of screw can accelerate the blend capability of polymer and make melt temperature more uniform. With increase of the vibration intensity, the effect of blend and plasticating is enhanced further. The average pressure gradient drops down the channel under the VFF because of lower virtual viscosity of polymer melt and smaller flow resistance in the channel. The comparison between the theoretical analysis and the experimental results shows the plasticating capability of melt is improved with increase of vibration intensity. 相似文献
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A novel approach is proposed to adjust flow nonuniformities caused by production variations from an extrusion die. A mathematical model that is based on the lubrication approximation was developed, and the effect of four types of production variations was examined separately. To each production variation, a specially designed choker bar was constructed and inserted into the extrusion die to correct flow nonuniformities. © 1994 John Wiley & Sons, Inc. 相似文献
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The numerical simulation of extrudate swell is significant in extrusion processing.Precise prediction of extrudate swell is propitious to the control of melt flow and the quality of final products.A mathematical model of three-dimensional(3D)viscoelastic flow through elliptical ring die for polymer extrusion was investigated.The penalty function formulation of viscoelastic incompressible fluid was introduced to the finite element model to analyze 3D extrusion problem.The discrete elastic viscous split stress(DEVSS)and streamline-upwind PetrovGalerkin(SUPG)technology were used to obtain stable simulation results.Free surface was updated by updating the streamlines which needs less memory space.According to numerical simulation results,the effect of zero-shear viscosity and elongation parameter on extrudate swell was slight,but with the increase of volumetric flow rate and relax time the extrudate swell ratio increased markedly.Finally,the numerical simulation of extrudate swell flow for low-density polyethylene(LDPE)melts was investigated and the results agreed well with others’work.These conclusions provided quantitative basis for the forecasting extrudate swell ratio and the controlling of extrusion productivity shape. 相似文献
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流线型挤出模参数化建模方法研究 总被引:1,自引:0,他引:1
在编程实现对型材截面轮廓凸凹性自动判断的基础上,采用射线法与比例间隔法相结合的方法,确定流道人口圆周上型值点的位置,以三次多项式作为流道模腔型曲线的数学模型,依据流线型要求给出的初始、边界条件得出型曲线的数学方程,构建了挤出模流道的三维参数化模型,为挤出模CAD/CAE的双向集成技术研究奠定基础。数值分析结果显示,该方法创建的流线型流道模型,其流动稳定性和平顺性都优于直线型流道。 相似文献
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弹性体短口型挤出胀大行为的研究 总被引:1,自引:0,他引:1
讨论了聚合物熔化经短口型挤出时的胀大现象及机理,提出了预测短口型挤出胀大的数学模型,并引用混炼胶毛细管实验测量数据进行初步验证,结果表明,挤出胀大比的理论计算值与实测值有良好的一致性。 相似文献
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A vibration force field was applied to the whole process of polymer plasticating extrusion by periodical vibration of the screw. It observably affected both the extruder screw extrusion characteristics and the round-section die extrusion characteristics. It also affected the polymer plasticating extrusion process and the quality of the extrudates. An analytical model of typical dynamic extrusion of round-section dies was created. The results showed that a vibration force field can improve extrusion output. 相似文献
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A three‐dimensional mathematical model was developed to investigate the nonisothermal, non‐Newtonian polymer flow through the dies used in the polystyrene foam extrusion process. The model, based on the computational fluid dynamics (CFD) code, Polyflow, allowed for the shear rate and temperature dependence of the shear viscosity of the blowing agent laden polystyrene melt. The model also accounted for viscous heating. The shear viscosity of the polystyrene‐blowing agent mixture was measured experimentally at several temperatures. The model was used to calculate pressure, flow, and temperature distributions in two different dies used for industrial‐scale extrusion of polystyrene foams. The article presents a selection of computed results to illustrate the effect of die design on uniformity of flow at the die exit, the overall pressure drop in the die, relative magnitudes of pressure drop in the land section versus the rest of the die, and temperature distribution in the die. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers. 相似文献
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The first stage of a study of the extrusion of starch-based materials is described. The chemical and physical changes which occur in the extrusion of a corn starch-water system relative to fifteen extruder variables have been investigated. A mathematical model of the extruder has been obtained from analysis of the data. The important variables were found to be moisture, barrel and die temperatures, screw speed and screw geometry. A strong interaction between moisture and barrel temperature was found to occur. These variables in the model account for 90.5% of the variance in the data obtained. The effects of the variables on the gelatinisation and shearing mechanical degradation of starch are discussed. 相似文献