富康轿车后车门杂物箱盖之气体辅助注射成型

气体辅助注射成型技术通过把高压气体注入到制件的厚壁处,在其内部形成气道,开辟了注射成型工艺应用的新领域。本文利用美国ＡＣＴ公司推出的Ｃ－ＭＯＬＤ软件,对富康轿车后车门杂物箱盖进行气辅成型ＣＡＥ分析。     

气体辅助注射成型充模流动CAE技术

在对气体辅助注射成型充填过程进行流动分析的基础上，开发了气体辅助注射成型充模流动ＣＡＥ软件，并给出了典型算例进行验证。     

富康轿车后车间杂物箱盖之气体辅助注射成型

利用美国ＡＣＴ公司推出的Ｃ－ＭＯＬＤ软件，对富康轿车后车门杂物箱盖进行气辅助成型ＣＡＥ分析，地几种方案进行分析比较，从中确定出一套最佳的工艺方案，通过改变浇口位置和适当地增加筋厚，解决了该制件筋注不满，气体不能完全穿透分布于所设计的气道内等问题，以实例说明了气体辅助注射成型的优越性。     

富康轿车后车门杂物箱盖之气体辅助注射成型

利用美国ＡＣＴ公司推出的Ｃ－ＭＯＬＤ软件,对富康轿车后车门杂物箱盖进行气辅成型ＣＡＥ分析,通过对几种方案进行分析比较,从中确定出一套最佳的工艺方案,通过改变浇口位置和适当增加筋厚,解决了该制件筋注不满,气体不能完全穿透分布于所设计的气道内等问题,以实例说明了气体辅助注射成型的优越性     

气体辅助注塑成型技术的应用

被业界称为注塑成型工艺第2次革命的气体辅助注射成型技术能解决或改善部分传统注塑成型方法的难点。本文介绍了气体辅助注射成型技术的基本机理及工艺控制过程，其中气体压力、注射压力、注射时间、气针与气道的位置尺寸等均对成品质量影响很大，列举了2个工艺实例，细述了传统注射成型与气辅注射成型的区别。     

奥拓轿车前保险杠注塑模浇系统的CAE分析

针对奥拓轿车前保险杠大型注塑模具,采用ＣＡＥ分析软件进行了优化设计。重点对注塑原料、设备和工艺进行了选择,并建立了制品的三维几何模型（包括浇口、气道的开设以及网格的划分等）,成功地完成了熔体动态充模ＣＡＥ模拟分析。分析结果表明,热流道四点进浇、四根气道及四个气体入口的对称布置方案是最理想的设计方案,热流道物气体辅助成型技术在大型注塑模上具有极大的应用前景。     

流体辅助塑料成型新技术

介绍了近年来气体辅助及其他介质辅助塑料成型的一些新技术,包括振动气体辅助成型技术、多腔控制气辅成型技术、气体辅助共注成型技术、气体辅助挤出成型技术,其他介质成型技术如水辅注射成型技术及液辅成型技术。最后展望了气辅及其他介质成型技术的发展趋势。     

气体辅助注射技术及其他介质辅助成型最新进展

概括地介绍了传统气体辅助注射技术的工艺及它的优缺点。并详细地介绍了气辅注射过程中的一些改进方法,如:外部气辅注射、局部气辅注射、振动气辅注射等,及运用其他介质的一些辅助成型方法,如:液体辅助注射(水辅注射)等新技术。     

气体辅助注射成型关键技术

气体辅助注射成型技术是传统注射成型技术的革新,是注塑成型工艺的二次革命。突破了传统注射成型的技术限制,具有许多传统注射成型所不具有的优点。但我国的气辅设备和气辅模具大多依赖进口。为促进气辅设备及模具的国产化,本文就气体辅助注射成型的关键技术进行了探讨。     

流体辅助注射成型技术

流体辅助注射成型技术是一种塑料与流体的复合注射技术，它包括气体辅助注射成型和水辅助注射成型2种形式。分别介绍了气体辅助注射成型和水辅助注射成型的工艺过程、设备及特点。     

A study of rib geometry for gas-assisted injection molding

Large, thin, plate-shaped parts usually are strengthened with structural ribs. Ribs also serve as gas channels with gas-assisted technology. The layout and geometry of these gas-channel ribs are critical to the gas-assisted injection molding (GAIM) process. In this study, the effects of rib geometry, including aspect ratio and fillet geometry, on the GAIM process are investigated. Experimental results indicate that increasing the rib width widens the allowable operation range and thus improves the moldability. Adding fillets to the rib corner significantly enhances the moldability. Adding fillets also reduces the loss of rigidity due to void formation in the rib. A curved fillet improves moldability and rigidity more than one that is straight.     

Analysis of a liquid‐assisted molding process for coating microchannels with an ultraviolet curable polymer

Injection molding can be altered to form hollow parts by partially pre‐filling a mold with polymer melt and then injecting a gas into the mold before cooling. The gas will core the center section and in the process force melt into the unfilled portions of the mold. This process is called gas‐assisted injection molding (GAIM) and is a thoroughly studied polymer processing technique. Liquid‐assisted molding follows the same principles as GAIM, except the coring fluid is a liquid of low viscosity. Liquid‐assisted molding of an ultraviolet (UV) curable polymer can be used to coat microchannels, the benefit of which being a smooth and circular cross‐section. Presented here are experiments of the controlled microchannel flow of a long, immiscible liquid thread through a viscous UV curable polymer. The roles of channel geometry and bubble velocity are discussed for square, rectangular, and circular microchannels. Finally, a quasi‐analytical model for calculating the Newtonian coating fluid thickness, when the coring fluid is driven by a constant pressure, was developed using the equation for Poiseuille‐like flow within a square channel. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

优化带加强筋ABS材料制件沉降斑的气体辅助成型技术

详细介绍了气体辅助注射成型的物理过程及其关键工艺参数对成型的影响。以带加强筋的绣花机外壳为例，考察了传统注射成型与气体辅助注射成型的优缺点。针对气体辅助注射引入的新工艺参数，介绍了一种CAE技术与统计学的Taguchi正交实验相结合的方法，设计L9(34)正交实验表在可成型范围内寻求最优工艺参数。结果表明，气体辅助技术能减少原料，对有加强筋的制件能有效地去除沉降斑、减弱不均匀收缩及减少内应力，大大改善制件的表面质量，增强制件尺寸的稳定性。     

Integrated simulations of structural performance,molding process,and warpage for gas‐assisted injection‐molded parts. III. Simulation of cyclic,transient variations in mold wall temperatures

Whether it is feasible to perform an integrated simulation for structural analysis, process simulation, as well as warpage calculation based on a unified CAE model for gas‐assisted injection molding (GAIM) is a great concern. In the present study, numerical algorithms based on the same CAE model used for process simulation regarding filling and packing stages were developed to simulate the cooling phase of GAIM considering the influence of the cooling system. The cycle‐averaged mold cavity surface temperature distribution within a steady cycle is first calculated based on a steady‐state approach to count for overall heat balance using three‐dimensional modified boundary element technique. The part temperature distribution and profiles, as well as the associated transient heat flux on plastic–mold interface, are then computed by a finite difference method in a decoupled manner. Finally, the difference between cycle‐averaged heat flux and transient heat flux is analyzed to obtain the cyclic, transient mold cavity surface temperatures. The analysis results for GAIM plates with semicircular gas channel design are illustrated and discussed. It was found that the difference in cycle‐averaged mold wall temperatures may be as high as 10°C and within a steady cycle, part temperatures may also vary ∼ 15°C. The conversion of gas channel into equivalent circular pipe and further simplified to two‐node elements using a line source approach not only affects the mold wall temperature calculation very slightly, but also reduces the computer time by 95%. This investigation indicates that it is feasible to achieve an integrated process simulation for GAIM under one CAE model, resulting in great computational efficiency for industrial application. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 339–351, 1999     

Temperature and shear rate distributions of gas-assisted injection molded (GAIM) polypropylene and the application in forecast of cooling time

An umbrella handle product of polypropylene molded by gas-assisted injection molding (GAIM) was studied from both aspects: theoretical modeling and simulation as well as in situ temperature measurement. The simulation was primarily through the use of the commercial software Moldflow (version 6.1) coupled with enthalpy transformation method (ETM) in an attempt to investigate the shear rate and temperature fields during GAIM process. A four-parameter model (FPM) was used to nonlinearly fit the temperature decays during the GAIM cooling stage on the basis of a three-parameter model (TPM) raised previously in our group. The FPM showed perfect fitting effect as well as presented fairly acceptable cooling time (t_c) prediction in comparison to experimental data, which could better reflect the nature of crystalline polymers during melt crystallization process. The understanding of the shear rate and temperature fields would be of practical importance to the further research on relationship of “processing–structure–property” as well as the optimization of cooling parameters for industrial GAIM operations of crystalline polymers. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47390.     

Simulation of a mold‐cooling process for gas‐assisted injection molded parts designed with a top rib on the gas channel

The same CAE model used for the filling and packing stage in the gas‐assisted injection molding (GAIM) process simulation was also applied to simulate the cooling phase. This was made possible by using the line source method for modeling cooling channels. The cycle‐averaged and cyclic transient mold cavity surface temperature distribution within a steady cycle was calculated using the three‐dimensional modified boundary element technique similar to that used in conventional injection molding. The analysis results for GAIM plates of a semicircular gas channel design attached with a top rib are illustrated and discussed. It was found that the difference in cycle‐averaged mold wall temperatures may be as high as 10°C, and within a steady cycle, part temperatures may also vary by about 15°C. The conversion of the gas channel into equivalent circular pipe and further simplification into two‐node elements using the line source method not only affects the mold wall temperature calculation very slightly but also reduces the computer time by 93%. This indicates that it is feasible to achieve an integrated process simulation for GAIM under one CAE model, resulting in great computational efficiency for industrial application.     

Study of “gas fingering” behavior in gas-assisted injection molding

A common problem encountered in gas-assisted injection molding (GAIM) is “gas fingering,” i.e., gas bubbles penetrating outside designed gas channels and forming finger-shaped branches. Severe gas fingering can result in significant reductions in part stiffness. In this paper, nondestructive techniques have been used to quantitatively characterize gas bubble geometry in specially designed GAIM parts. Based on the quantitative measurements, the most crucial process parameters to control gas fingering have been identified through factorial design experiments. More detailed process studies reveal that there is an intrinsic relationship between gas fingering and cross-sectional gas bubble shape. By examining the effects of gas channel design and material type on the gas bubble shape, some useful gas channel design guidelines have been obtained.     

气体辅助注射成型工艺参数优化研究

为了解决气体辅助注射成型(GAIM)中制品所出现的缺陷,采用数值模拟方法对影响制品质量的工艺参数进行了优化研究.首先,建立GAIM过程的数学模型,得出影响GAIM制品质量的主要工艺因素;随后,利用数值模拟法分析熔体预注射量、熔体/气体延迟时间、充气压力与熔体注射温度等关键工艺因素与GAIM制品缺陷的关系;最后,基于数值模拟分析结果,对GAIM制品的工艺参数进行了优化选择与设定.     

Flow direction when fan shaped geometry is applied in gas-assisted injection molding: 2. Development of flow model and its predictions

In part 2 of the paper simplified unsteady-mass (and momentum-) balance equations of melt polymer resin in the cavities of GAIM were proposed, as a time-dependent rule of thumb, to constitute a novel flow model in GAIM under the configuration of two fan-shaped geometries connected with a gas nozzle. Upon performing a simulation on them with commercial software (MOLDFLOW), we compared the time evolution of simulated gas penetration lengths with the those of unsteady trajectory on the gas flow in GAIM by the suggested novel flow model in the fan-shaped cavities in order to check the precision of model-predicted gas penetration lengths as well as the consistency of its predicted direction. The results by the suggested novel flow model were satisfactory to fit the trajectory simulated with commercial software (MOLDFLOW).     

气辅注塑结晶型塑料制品冷却时间的确定

针对气辅注塑结晶型塑料制品的特征对其冷却模型进行了简化，并通过精确分析解法和积分近似解法相结合对该模型进行了推导求解，得出了气辅注塑结晶型塑料制品在冷却过程中的温度场分布和冷却时间，对实际生产过程有一定的指导作用。