【作者】 王斌；

【导师】 于同敏；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2006， 硕士

【摘要】 随着微机电系统技术的发展对微型制件需求的不断增长,以传统的微细加工方法成形微小制件难以满足微系统的应用要求,而用微注塑成型的方法成型微小制件,具有生产效率高,制件质量稳定等优点,成为微成形加工领域的重要工艺发展方向。 由于微型塑件的结构尺寸与体积微小,传统的宏观上的注塑模具设计理论及方法在某种程度上已经失去指导意义,需要从微观尺度上根据微型塑件成型的特点,建立新的微注塑模具设计的基本理论与方法。因此研究微小熔体在模具型腔中的流动行为成为微型模具设计理论研究的重要内容,其中建立适合微注塑成型充模流动的理论模型是关键。 本文依据塑料流变学、流体力学等基本理论,借鉴宏观熔体的充模流动理论模型,比较了微型注塑成型技术与传统注塑成型技术的差异,对微观熔体充模过程中的诸多可能的影响因素,如模具和熔体温度、流动过程的非等温特性、型腔排气、流动通道的表面粗糙度、熔体的表面张力、惯性力与重力、微观粘度、粘性耗热、粘弹效应等进行了全面分析,初步建立了反映微观熔体充模流动行为的理论模型。进而,采用Polyflow等流体分析软件对模型中的影响因素进行模拟,根据模拟结果进一步完善了理论模型。最后,本文引用美国俄亥俄大学的Liyong Yu博士的实验结果,分别对200μm和100μm两种宽度的微流道进行充模流动模拟,并将模拟结果与实验数据进行对比,验证了理论模型的正确性,同时分析了模拟结果与实验数据之间产生误差的原因。 通过模拟结果的分析可知,考虑壁面滑移影响和采用局部热对流系数能够较好的反映温度变化、流道表面粗糙度和熔体弹性等因素对微小熔体充模流动行为的影响。本文所建立的理论模型在微小流动通道中的充模长度预测上已经得到了较好的验证,能够反映出微型模具通道中熔体的充模流动行为,为微型注塑模具设计理论奠定了有力的基础。更多还原

【Abstract】 Due to the increasing demand for micro products along with the development of micro electromechnical system technology, fabricating micro products by traditional microfabrication technology can hardly meet the requirement of microsystem. Nevertheless, fabricating micro parts by micro injection molding technology has become an important development trend for its high efficiency, stable quality and so on.For the miniature of structure size and volume of micro plastics parts, the traditional design theories for injection mold have lost their instructional significance in some sense. New design theories and methods for micro injection mold should be built according to the characteristics of micro injection molding on microscale. So the research of microscale melt flow behavior in mold cavity becomes an important part of micromold design theories very much, in which the key is establishing theory model suited for micro injection molding.According to the basic theories such as plastic rheology, hydrodynamics etc, using the macroscale melt filling flow theory for reference, comparing the micro injection molding technology with the traditional one, and analyzing some possible influencing factors on micro filling process comprehensively, such as non-isothermal feature in flow process, cavity venting, surface roughness of flow channel, surface tension of melt, gravity and inertia, microscale viscosity, viscous heating and viscoelastic effect, etc, the paper establishes a theory model that reflects micro scale melt flow behavior primarily. Then adopting fluid analysis software, such as Polyflow, etc, simulates effect factors in the model, and improves the theory model according to the simulation results further. Finally, the paper cites the experiment results investigated by Liyong Yu, the doctor of the Ohio States University, simulates the filling processes in two kinds of micro channels which are 200μm and 100μm respectively, contrasts simulation results with experiment data, validates the correctness of theory model, and analyzes the reasons for the errors between the simulation results and experiment data.Through analyzing the simulation results, can know that, considering wall slip effect and adopting local heat transfer coefficient can reflect the effects that is temperature change, surface roughness of flow channel and melt elasticity, etc, to micro melt filling flow behavior. The theory model established in this paper is proved its validity for the prediction of fillinglength in micro flow channels better, can reflect melt filling flow behavior in micro mold channels, and establishes valuable foundation for micro injection mold design theories.更多还原