共查询到18条相似文献,搜索用时 203 毫秒
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为了建立气辅控制系统的控制模型,系统研究了气辅注射工艺参数对气辅共注成型过程的影响规律。研究表明,保压时间和气体注射延迟时间对气辅共注成型的气体穿透有较大影响,而对芯层熔体的穿透影响不明显。随着保压时间的延长,气体的穿透深度和穿透宽度均增加,而随着气体注射延迟时间的延长,气体穿透深度增大,穿透宽度减小。延长气体注射延迟时间有利于气体的穿透,但易出现指进现象和气体穿透流动的不稳定。 相似文献
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对先进的气辅共注成型工艺进行了系统的实验研究,研究了熔体注射温度、气体压力这两种工艺参数对气辅共注成型气体和芯层熔体穿透形貌的影响规律,并基于聚合物流变学和流体动力学揭示了这些工艺参数对成型过程的影响机理。结果表明,随着芯层熔体温度升高,芯层熔体的黏度会减小,流动阻力减小,使得气腔的穿透深度减小,而穿透宽度和穿透厚度则增大,但芯层熔体的穿透长度变化不明显;随着注气压力增大,气体的穿透深度、穿透宽度和穿透厚度均增大。 相似文献
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工艺条件对气体辅助注射成型的影响 总被引:1,自引:0,他引:1
基于Hele-Shaw模型,采用CAE技术,利用Moldflow软件对气体辅助注射成型过程中熔体注射温度、熔体预填充量、气体注射压力、延迟时间等重要工艺参数与气体穿透深度、熔体厚度和体积填充时间等重要指标的关系进行了数值模拟.结果表明,熔体注射温度和气体注射压力越高、延迟时间越短,则气体穿透深度越小、熔体厚度越薄、体积填充时间越短;熔体预注射量越大,则气体穿透深度越小、熔体厚度越厚、体积填充时间越短. 相似文献
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《塑料》2015,(6)
基于自行构建的气体辅助共注塑实验平台,对圆管件的溢料法气辅共注塑(OGACIM,overflow gas assisted co-injection molding)工艺进行了实验研究。单因素法考察了内层熔体注射延迟时间和内层熔体流率对内层熔体和气体穿透率的影响,结果表明:随着内层熔体注射延迟时间的减小和内层熔体流率的增加,内层熔体和气体穿透率均会增加;正交实验法考察了5个工艺参数(注气压力、注气延迟时间、内层熔体注射延迟时间、内层熔体温度和内层熔体流率)之间交互作用对内层熔体和气体穿透率的影响,内层熔体和气体穿透率均主要受注气延迟时间和注气压力的影响,缩短注气延迟时间和增大注气压力均可增大内层熔体和气体穿透率。 相似文献
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为优化气辅成型工艺参数,采用单因素法考察工艺参数对气辅成型质量的影响,以熔体预注射量、熔体温度、模具温度、注气压力、延迟时间、注气时间为因素,气体穿透深度、最大气指幅度为评价指标,采用L25(56)正交试验设计优选气辅成型工艺参数为:熔体预注射量85%,熔体温度240?℃,模具温度40?℃,延迟时间4?s,注气压力3?... 相似文献
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Shiu‐Wu Chau 《Polymer Engineering and Science》2008,48(9):1801-1814
This article proposes a generalized Newtonian model to predict the three‐dimensional gas penetration phenomenon in the GAIM process, where the gas and melt compressibility are both taken into account and hence the primary and secondary penetrations in GAIM processes are able to be quantitatively predicted. Additionally, an incompressible model requiring no outflow boundary is also presented to emphasis the influence of gas compressibility on the primary penetration. Based on a finite volume discretization, the proposed numerical model solves the complete momentum equation with two front transport equations, which are employed to track the gas/melt and air/melt interfaces. The modified Cross‐WLF model is adopted to describe the melt rheological behavior. The two‐domain modified Tait equation is exploited to represent the melt compressibility, while a polytropic model is employed to express the gas compressibility. The proposed schemes are quantitatively validated by the gas penetration characteristics in a clip‐shaped square tube, where good prediction accuracy is obtained. The influences of five major molding parameters, such as the injection pressure, mold temperature, melt temperature, delay time, and melt material on the gas penetration characteristics in the same clip‐shaped square tube via the proposed numerical approach are extensively presented and discussed. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
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Tang‐Qing Kuang Jun‐Yu Pan Qiang Feng He‐Sheng Liu Bai‐Ping Xu Wen‐Wen Liu Lih‐Sheng Turng 《Polymer Engineering and Science》2019,59(2):295-303
Water‐powered projectile‐assisted injection molding (W‐PAIM) is an innovative molding process for the production of hollow shaped polymer parts. The W‐PAIM utilizes high pressure water as a power to drive a solid projectile to displace the molten polymer core to form the hollow space. The residual wall thickness (RWT) and its distribution are the important quality criteria. The experimental and numerical investigations were conducted. Experimental specimens showed that the RWT of a W‐PAIM pipe was much thinner than that of a water‐assisted injection molding pipe. The cross‐section size of the projectile defined the basic penetration section size. The software FLUENT was used to obtain the instantaneous distributions of the flow field, which revealed the forming mechanism of the RWT. The experiments indicated that the processing parameters, such as melt temperature, melt injection pressure, mold temperature, and water injection delay time had obvious effects on the RWT, while the water pressure had little effect on it. The RWT of curved pipes was thin at the inner concave side while thick at the outer convex side. The RWTs at the bend portion are influenced by the deflection angle and bending radius, which is due to the pressure difference between the two sides. POLYM. ENG. SCI., 59:295–303, 2019. © 2018 Society of Plastics Engineers 相似文献
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给出气液两相流数学模型,选取Cross-WLF模型作为熔体的黏度模型,采用Level Set/SIMPLEC方法模拟了气体辅助注射成型中气体穿透过程,追踪到了不同时刻的运动界面(气熔界面和熔体前沿界面),描述了运动过程中不同时刻速度和温度等重要物理量的分布情况,分析了熔体温度、气体延迟时间和注射压力对气体穿透时间和穿透长度的影响。数值结果表明,Level Set/SIMPLEC方法可以准确追踪气体穿透过程中的两个运动界面;熔体温度、延迟时间和气体注射压力对气体穿透长度有显著影响。 相似文献
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Characteristics of gas penetration and polymer melt flow in gas-assisted injection molded spiral tubes was investigated by simulations and experiments. Distribution of the skin melt thickness along the gas flow direction was measured, and gas penetration in the primary and secondary stages was identified. An algorithm based on the control-volume/tiniteelement method combined with a particle-tracing scheme using a dual-filling-parameter technique is utilized to predict the advancements of both melt front and gas from during the molding process. The simulated distribution of gas penetration shows reasonably good coincidence with experimental observations. © 1995 John Wiley & Sons, Inc. 相似文献
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建立水辅助注射成型二维、瞬态、非定常流动模型,采用黏度幂律模型,在k ω湍流模型下,充分考虑注射水的湍流特性以及熔体前沿的喷注效应,采用有限体积法(VOF)对充填过程中的注水速度、注水温度和注水延迟时间等注水控制参数的影响进行数值模拟。结果表明,注水速度的增加会增加水在熔体中的穿透长度,并且会减小残余壁厚;注水温度对水的穿透长度和残余壁厚的影响均不显著;随着注水延迟时间的增长,水的穿透长度和残余壁厚均有增加的趋势。 相似文献