Gas-assisted injection molding is a polymer processing technology in which a penetrating gas bubble hollows out a plastic part as it cools and solidifies within a mold. In this study, non-isothermal gas injection experiments at high capillary number illustrate the effects of delay time in gas injection, tube diameter, capillary number, and temperature-sensitive fluid viscosity and flow activation energy on coating thickness. Experiments with polybutene H-300 and Dow Corning silicon oil (DC-200) in stainless steel tubing (1.27 and 0.635 cm) demonstrated fractional coverage increasing from 0.6 to a maximum in the range of 0.63–0.83 at short delay times, then decaying toward 0.6 at long delay times upon approaching the cooled isothermal state. Further analysis is drawn from simulations based on a simple theoretical model incorporating one-dimensional heat transfer with convection at the outer surface of the mold, non-isothermal behavior of the viscous fluid, and radial velocity profiles in the one-phase fluid flow region. Quantitative agreement is found between experimental and simulated results. Two-dimensional modeling and simulation methods extend the prior results to illustrate transient axial and radial heat transfer as well as flow behavior with respect to the penetrating gas bubble within the fluid flow region.

中文翻译：

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气体辅助注射成型中高毛细管数下粘性牛顿流体的非等温气体辅助置换

气体辅助注射成型是一种聚合物加工技术，当塑料部件在模具内冷却和固化时，渗透气泡将塑料部件掏空。在本研究中，高毛细管数下的非等温注气实验说明了注气延迟时间、管径、毛细管数以及温度敏感流体粘度和流动活化能对涂层厚度的影响。在不锈钢管（1.27 和 0.635 cm）中使用聚丁烯 H-300 和道康宁硅油 (DC-200) 进行的实验表明，在较短的延迟时间内，部分覆盖率从 0.6 增加到 0.63-0.83 范围内的最大值，然后向0.6 在接近冷却等温状态时的长延迟时间。进一步的分析基于一个简单的理论模型进行的模拟，该模型结合了模具外表面对流的一维传热、粘性流体的非等温行为以及单相流体流动区域中的径向速度分布。在实验和模拟结果之间发现了定量的一致性。二维建模和模拟方法扩展了先前的结果，以说明瞬态轴向和径向传热以及流体流动区域内穿透气泡的流动行为。