共查询到17条相似文献,搜索用时 157 毫秒
1.
聚合物熔体在长圆导管中正弦脉动流动过程研究 总被引:1,自引:0,他引:1
研究聚合物熔体在长圆导管中正弦脉动流动的过程,从理论上研究了压力梯度变化时,产量和功率的变化;以及产量变化时,压力和功率的变化。并通过在毛细管流变仪上的试验,验证了引入振动力场能够提高挤出加工的生产率,有效地降低聚合物熔体通过长圆导管流道成型所需的能耗这一理论结果。说明该理论结果对于指导动态圆管流道的实际生产具有十分重要的工程意义。 相似文献
2.
为了研究超声波作用下的聚合物材料流动性能及其影响因素,利用自主开发的聚合物超声波辅助挤出测试系统,进行了超声波作用下聚合物熔体在微流道管壁的剪切力、剪切速率和表观黏度的测试,并在与传统稳态挤出相比较基础上,分析了超声波对微流道中聚合物熔体流动性能的影响。实验结果表明,引入超声振动后,微流道的入口压力降有明显降低,并且随着熔体剪切速率的增加而增大;超声振动作用下聚合物熔体剪切速率存在临界值,当剪切速率小于临界值时,超声下聚合物黏度小于传统稳态挤出聚合物黏度,反之,超声聚合物黏度大于传统挤出聚合物黏度。 相似文献
3.
4.
5.
动态成型注塑螺杆熔体输送能力的研究 总被引:1,自引:0,他引:1
根据动态注射成型时螺杆的工作特点,采用自行修正的Tanner本构方程研究了聚合物熔体在螺槽中的等温流动。同时,近似地给出了振动力场下注塑螺杆熔体输送能力的表达式,理论分析了振动参数对沿程压力降及动态成型熔体输送能力的影响。结果表明,振动力场使塑化过程中聚合物的粘度降低,流动阻力减小。沿螺槽方向的平均压力降减小,在保持成型条件不变的情况下,施加振动可以提高熔体输送能力。 相似文献
6.
聚合物熔体缝模内脉动挤出过程的研究 总被引:1,自引:0,他引:1
研究了振动场作用下聚合物熔体通过狭缝型流道的脉动挤出过程,探讨了振动参数与聚合物熔体铗缝流的压力降和流率之间的相互关系。结果表明,随着振动场频率和振幅的增加,聚合物熔体狭缝流的压力降减小,流量增率增大。 相似文献
7.
建立了模具锥形流道中熔体的动态表观粘度模型,通过实验的方法测得流道两端压力降,表征出动态充模过程流道中熔体的实际表观粘度。依靠实验及数据计算,检验此模型能够灵敏地定量反映外部加工条件对熔体表观粘度的影响。结果表明,在频率4Hz、振幅40μm时聚丙烯的注射充模表观粘度为最小,此模型的提出也为寻求其他聚合物动态注射时的最优振动加工参数组合提供了依据。 相似文献
8.
9.
10.
11.
Wu Hong-wu Xu hai-hang Qu Jin-ping Zhang Shao-dan 《Polymer-Plastics Technology and Engineering》2013,52(8):935-937
Employing a spiral channel mold and a set of cavity pressure measurement equipments from Kistler, the cavity pressure response and the maximum flow length during dynamic injection molding were studied. The processing conditions include injection velocity, injection pressure, mold temperature, vibration frequency, and vibration amplitude. The result shows that the maximum flow length can be improved by the dynamic injection molding. Especially at the lower injection pressure, the maximum flow length can be improved about 15%. From the curves of cavity pressure, we found that the cavity pressure undulated regularly in the dynamic filling phase, which is conduced by the screw vibration. During dynamic injection molding, the viscosity of the polymer flow reduces, and the capability of mold filling improves. 相似文献
12.
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
13.
为了研究振动场作用下聚合物低温塑化成型过程,研制了一套球型螺杆电磁激振挤出装置,建立了振动场作用下聚合物低温塑化成型的物理模型,深入分析了振动场作用下聚合物低温塑化机理,然后从振动耗散能、聚合物变形能、摩擦热、剪切热等方面分析了聚合物塑化的能量来源,并通过数学推导得出了能量输送密度的数学表达式。最后使用球型螺杆电磁激振实验台和低密度聚乙烯(LDPE)进行实验和理论计算,实验结果与理论计算结果符合很好,并得出结论:振动场的引入可以降低聚合物的成型温度40℃以上、可以节约单位质量物料成型能耗47%以上,同时可以提高制品力学强度。本研究将会为聚合低温成型工艺和成型设备的研究提供可靠的理论基础。 相似文献
14.
15.
16.
Wire coating extrusion was studied, both experimentally and theoretically, using a pressure-type die. For the experimental study, a wire coating apparatus of laboratory scale was constructed, consisting of a pay-off device, extruder, cross-head and pressure-type die, cooling trough, and take-up device. The materials used were low- and high-density polyethylenes and thermoplastic rubber. The following measurements were taken during the experiments: (1) the axial pressure profiles in the die, (2) melt flow rate, and (3) take-up speed. The measurements were then used to determine the effect of the rheological properties of the polymers on the performance of the wire coating operation. It was found that a reduction in axial pressure gradient and a reduction in the recoverable elastic strain of a molten polymer at the die exit can be realized as the speed of the wire is increased. For the theoretical study, using a power-law model, the equations of motion were solved numerically to predict the volumetric flow rate as functions of the pressure gradient in the die and the rheological properties of the polymer being extruded. Solution of the system equations permitted us to predict the velocity profile and shear stress distributions of a molten polymer inside a pressure-type wire coating die. 相似文献