超声辅助注射成型充模流动特性的可视化研究

发布时间：2018-10-20 20:33

【摘要】：超声技术是集物理学、振动学、声学等多学科交叉的一门新技术,随着科学界对超声技术研究的深入,超声技术在生物医学、材料科学等领域得到广泛应用。将超声技术应用于聚合物注射成型过程中,发挥超声在降低熔体粘度,提高塑件成型质量方面的优势,成为注射成型的一种新方法。但是超声振动如何影响聚合物充模流动,以及其对聚合物充模流动的作用机理仍不清楚,本文针对这个问题,提出利用可视化示踪法,探讨超声振动对聚合物流动过程的影响。本文以矩形平板塑件为研究对象,设计集超声外场作用与可视化技术的注塑成型模具,实现一个模具上多位置超声激励的组合施加,利用此模具对聚丙烯(PP)材料进行不同超声功率和注射速率参数下的注射成型实验,结合示踪粒子标记法和多项式数据拟合,研究超声振动对熔体流动轨迹、塑件收缩方向以及熔体流动速度的影响。结果发现,超声振动一方面使得熔体在型腔内更长距离上保持直线流动,冷却阶段塑件收缩平衡点位置向型腔末端移动；另一方面,能够在一定程度上促进PP熔体前沿的流动,最大提高幅度为35.2%。同时,前沿熔体流动速度曲线呈先降低,后升高,再降低,再上升,最后下降的变化趋势。结合示踪粒子标记法和Kringing插值法提出一种充型流动速度场的表征方法,实验数据表明,一方面,熔体充模过程速度分布呈中间高,两边低,近浇口高,远浇口低的变化趋势；施加超声振动后,熔体流动速度增大,沿流动方向流动速度变化梯度减小。另一方面,从熔体流动速度的大小以及速度分布的均匀性角度上考虑,lmm塑件注射成型时,800W功率超声对型腔内熔体流动速度的提升最明显,600W、400W、100W次之,200W功率超声对流动速度的提高幅度最小；3,5mm塑件注塑成型时,200W功率超声对型腔内部速度场的改善最为显著,800W、1OOW次之。
[Abstract]:Ultrasonic technology is a new interdisciplinary technology in physics, vibration, acoustics and so on. With the development of ultrasonic technology in science, ultrasonic technology has been widely used in biomedicine, material science and other fields. The application of ultrasonic technology in polymer injection molding process has become a new method for injection molding, which brings into play the advantages of ultrasonic in reducing melt viscosity and improving the molding quality of plastic parts. However, how ultrasonic vibration affects polymer filling flow and its mechanism of action on polymer filling flow are still unclear. In this paper, a visual tracer method is proposed to study the effect of ultrasonic vibration on polymer flow process. In this paper, the rectangular plate plastic parts are taken as the research object, and the injection molding mould with ultrasonic external field action and visualization technology is designed to realize the combination of multi-position ultrasonic excitation on a mould. The injection molding experiments of polypropylene (PP) materials under different ultrasonic power and injection rate parameters were carried out by using this mould. The ultrasonic vibration effect on melt flow trajectory was studied by combining the tracer particle marking method and polynomial data fitting. The influence of shrinkage direction and melt flow velocity of plastic parts. The results show that, on the one hand, ultrasonic vibration keeps the melt flowing at a longer distance in the cavity, and the equilibrium position of the plastic part shrinks to the end of the cavity in the cooling stage, on the other hand, it can promote the flow of the PP melt front to a certain extent. The maximum increase was 35.2a. At the same time, the front melt flow velocity curve decreases first, then increases, then decreases, then rises, and finally decreases. Combined with tracer particle marker method and Kringing interpolation method, a new method for characterizing the flow velocity field of filling mold is proposed. The experimental data show that, on the one hand, the velocity distribution of melt filling process is high in the middle, low in both sides, high in near gate and low in far gate. When ultrasonic vibration is applied, the melt flow velocity increases and the gradient of flow velocity decreases along the flow direction. On the other hand, From the point of view of the size of melt flow velocity and the uniformity of velocity distribution, in injection molding of lmm plastic parts, 800W power ultrasound has the most obvious increase of melt flow velocity in cavity, 600W / 400W / 100W, 200W / 100W, and 200W / 100W respectively. In the injection molding of 3mm 5mm plastic parts, the improvement of the velocity field in the cavity by 200W power ultrasound is the most remarkable, and the velocity field of the cavity is the second by 800W 1OOW.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TQ320.66;TB559

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