共查询到19条相似文献,搜索用时 109 毫秒
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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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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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以一个具有气辅成型典型结构的塑料制品为研究对象,通过物理实验和全三维数值模拟结合的方法,研究了不同延迟时间时的气辅成型中气体穿透行为,对结果进行了分析和探讨。结果表明,延迟时间对气体穿透长度、气指尺度和残余壁厚等衡量气辅成型质量的关键参数有较大的影响。 相似文献
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对气辅成型制品翘曲缺陷采用正交实验方法和数值模拟方法进行了研究。研究了气体注射延迟时间与气体注射压力及气体注射时间与气体注射压力两对工艺参数的交互作用对制品翘曲缺陷的影响。结果表明,对制品翘曲影响最为严重的是气体注射时间与气体注射压力的交互作用。较长的延时可以减轻制品翘曲的程度,但气体无法穿透或穿透不足等问题也是延时过长会造成的,因此选择合适的气体注射时间与气体注射压力以及气体延时组合非常重要。 相似文献
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本文结合国内外对气辅成型工艺的研究。比较了气辅成型和传统的注射成型成型制件的优缺点。通过讨论在气辅成型过程中,熔体预注射量、气体延迟时间和气体压力等工艺参数对制品性能的影响,揭示了影响制品性能的内在因素取向机理在气辅成型和传统的注射成型成型的不同及气辅成型技术研究发展的趋势。 相似文献
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基于气体辅助注塑成型过程的三维数值模拟,利用Taguchi实验方法设计了L9(34)实验矩阵,采用标准方差分析方法,分析了预注射量、注射温度、气体压力和延迟时间等工艺因素对气体穿透深度的影响,预测了优化工艺组合下的气体穿透深度。研究表明:在所选择的工艺因素中,对气体穿透深度影响程度依次为预注射量(F=87.8%)、气体延迟时间(F=8.1%)、气体压力(F=3.5%)和注射温度(F=0.6%)(F为因子重要性)。在优化工艺组合下预测的气体相对穿透深度为87.1%,与模拟计算值符合较好。 相似文献
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采用空气-水体系,对装有4种不同规格规整丝网填料的旋转填充床的压降特性进行了实验研究,考察了转速、气体流量、液体流量等操作参数及填料特性对气相压降的影响规律,并与传统不锈钢波纹丝网填料旋转填充床压降进行了比较. 结果表明,装有规整丝网填料的旋转填充床压降可降低35%~70%. 进一步采用压降较低的规整丝网填料以(NH4)2SO3为吸收剂进行氨法脱硫性能研究,结果表明,随转子转速和(NH4)2SO3浓度增大,SO2脱除率升高;随进气口SO2浓度升高及气液比增大,SO2脱除率降低;SO2脱除率最高可达97%,可满足国家排放标准. 相似文献
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Robert J. Kirk Minesh R. Tendulkar Panayiotis K. Kolliopoulos Yijie Wang Xutao Shi Kurt W. Koelling 《Polymer Engineering and Science》2021,61(7):1956-1970
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. 相似文献
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Mian Hamood‐ur‐Rehman Farhad Ein‐Mozaffari Yaser Dahman 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(5):887-896
BACKGROUND: Airlift bioreactors have been used extensively in biotechnology industries in recent years in a variety of arrangements and applications. The insertion of packing inside the bioreactors has the potential to provide high productivity within a compact size through utilizing immobilized species. RESULTS: A novel recirculating external loop airlift bioreactor that has two rolls of fiberglass packing and a gas distributor in between was designed and built. Electrical resistance tomography (ERT) images showed that the gas holdup increased after installing the packing and the gas distributor. Gas holdup in the riser increased with decreasing static liquid height in the bioreactor. This decreased the liquid superficial velocity, which contributed to a higher gas holdup in the bioreactor. Results also showed that riser gas holdup varied slightly with different sparger configurations. Higher gas holdup increases the oxygen mass transfer rate by increasing the residence time and interfacial mass transfer area. CONCLUSION: ERT results showed that fiberglass packing with an installed gas distributor in bioreactors can achieve higher gas holdup at higher superficial gas velocity. This can contribute to improved conversion in bioreactors with packing through utilizing higher biomass concentrations and higher oxygen concentration. © 2012 Society of Chemical Industry 相似文献
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偏氟乙烯聚合反应器气液传质特性的研究 总被引:4,自引:0,他引:4
采用纯氧物理吸收法在直径为300mm的有机玻璃釜中测定气液容积传质系数KLa。研究了桨型、装料高度、桨叶位置及桨叶直径对KLa的影响。结果表明,随着液深的增加或桨叶安装位置的提高,KLa值下降;而桨径增加,KLa值增加。 相似文献
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气体辅助注塑成型技术 总被引:3,自引:0,他引:3
介绍一种新的塑料加工技术——气体辅助注塑成型技术的工艺过程和设备配置,分析了其成型特点和典型应用。根据气辅成型的不同工艺过程,可分为标准成型法、副腔成型法、熔体回流法和活动型芯法四种。气辅成型所用设备包括注塑机、气辅装置、进气喷嘴等。其特点是所需注射压力小、制品翘曲变形小、可消除缩痕,提高表面质量、适用于成型壁厚差异较大的制品、在不增加制品重量的情况下可增加制品的刚度和强度、对一般制品可通过气体的穿透,减轻重量,缩短成型周期。典型的应用是制作刷柄、扶手、方向盘等棒形或管形件,汽车仪表盘等大的板形件,厚薄不均的各种家电外壳和塑料家具等。 相似文献