塑料挤出吹塑冷却阶段温度场的有限元分析

挤出吹塑中冷却与固化阶段温度场的演化对制品的最终性能有很大的影响。首先,建立塑料挤出吹塑制品冷却过程热传递问题的教学模型；然后,利用有限元软体POLYFLOW求解数学模型获得制品冷却过程的温度场；最后,在有限元模型基础上分析了不同内冷方式、制品壁厚以及初始温度对制品温度场的影响。     

挤出吹塑实验研究进展

对挤出吹塑过程的三个阶段：型坯成型、型坯吹胀以及制品冷却与固化阶段的实验方法和装置的研究现状进行了详细论述。     

吹塑成型CAE技术研究与应用现状分析

吹塑成型是成型中空塑料制品的主要成型方法,其成型过程包括型坯成型、型坯吹胀和制品的冷却固化三个阶段。中空制品的吹型成型质量受各种工艺因素的影响,包括熔融温度、吹胀压力、拉仲速率、冷却时间、聚合物材料柱能等。吹塑成型数值模拟可预测制品的壁厚均匀性,残余应力和收缩状况等,指导吹塑成型模具的优化设计,并通过优化工艺参数获得最佳性能的吹塑制品。本文对吹塑成型CAE技术的发展状况进行了详细研究,并对其应用现状作了简单分析。     

挤出吹塑中制品冷却的研究进展

系统地介绍了挤出吹塑中制品冷却这一复杂阶段的研究现状，同时简要介绍了将ANSYS有限元软件应用于此阶段的研究工作。     

中空吹塑成型过程数值分析技术的进展

论文对塑料中空吹塑成型过程数值分析的研究和发展状况进行了全面的阐述，针对成型过程的三个阶段：型坯形成，型坯吹胀以及冷却与固化阶段因内外研究者进行数值分析的具体谅才理论依据进行了较详细的论述，并指出毛坯熔融挤出，吹胀成型、冷却和固化是成型周期中紧密衔接的三个过程，目前对各个阶段分别进行研究的较多，而综合考虑气压、温度、冷却时间、高分子材料性能等因素对全过程进行数值模拟的较少见报道，因此还有许多研究工     

化工出版社塑料类新书介绍

《塑料吹塑成型与实例》ISBN7-5025-7588-X,李树、贾毅编著,大32开,平装,定价29·00元。本书以实用性、知识性为编写准则,全面讲解了吹塑制品设计、挤出吹塑成型、注射吹塑成型、拉伸吹塑成型、大型容器的吹塑成型、多层复合吹塑成型、型坯膨胀、吹塑冷却与模拟技术、吹塑制品的表面修饰等的工艺操作技术、材料选用与设备等,对生产过程中的故障及产品缺陷进行了分析与解决,并以典型吹塑制品为例,介绍了它们的配料、成型设备、成型工艺、废料回收等内容。本书内容简明易懂,图文并茂,并配有大量的实例和参考数据,反映了当前先进的吹塑成型技…     

2002年机械工业塑料机械科技信息网技术交流会论文集

现我杂志社有少量《2 0 0 2机械工业塑料机械科技信息网技术交流会》论文集 ,有需要者请与刘琳玲女士联系 ,电话 0 10 - 6 890 5 2 5 3,数量有限 ,欲购从速。目录如下 :1 单螺杆塑料挤出机固体输送机理研究的发展与趋势2 塑料挤出吹塑中制品冷却与固化理论研究的进展3 多层共挤吹膜机械的技术与发展4 全液压式注塑机的最新技术进展5 注塑机合模装置分析与展望6 论快速成型技术的发展方向7 浅谈微灌设备的应用及发展8 精密挤出成型的研究9 混炼型锥形双螺杆实验研究10 塑料三通管挤胀成型过程的运动学研究11 塑料挤出吹塑—机理研究及纳…     

2002年机械工业塑料机械科技信息网技术交流会论文集

现我杂志社有少量《2 0 0 2机械工业塑料机械科技信息网技术交流会》论文集,有需要者请与刘琳玲女士联系,电话:0 10 -68985 2 5 3 ,数量有限,欲购从速。目录如下:1 单螺杆塑料挤出机固体输送机理研究的发展与趋势2 塑料挤出吹塑中制品冷却与固化理论研究的进展3 多层共挤吹膜机械的技术与发展4 全液压式注塑机的最新技术进展5 注塑机合模装置分析与展望6 论快速成型技术的发展方向7 浅谈微灌设备的应用及发展8 精密挤出成型的研究9 混炼型锥形双螺杆实验研究10 塑料三通管挤胀成型过程的运动学研究11 塑料挤出吹塑———机理研究及纳米…     

聚碳酸酯挤出吹塑成型工艺

论述聚碳酸酯挤出吹塑成型工艺控制及成型过程中制品产生缺陷解决办法,介绍了挤出吹塑饮料瓶的成型工艺。     

2002年机械工业塑料机械科技信息网技术交流会论文集

现我杂志社有少量《2 0 0 2机械工业塑料机械科技信息网技术交流会》论文集 ,有需要者请与刘琳玲女士联系 ,电话 :0 10 -6890 5 2 5 3 ,数量有限 ,欲购从速。目录如下 :1 单螺杆塑料挤出机固体输送机理研究的发展与趋势2 塑料挤出吹塑中制品冷却与固化理论研究的进展3 多层共挤吹膜机械的技术与发展4 全液压式注塑机的最新技术进展5 注塑机合模装置分析与展望6 论快速成型技术的发展方向7 浅谈微灌设备的应用及发展8 精密挤出成型的研究9 混炼型锥形双螺杆实验研究10 塑料三通管挤胀成型过程的运动学研究11 塑料挤出吹塑———机理研究…     

高温熔融高炉渣颗粒相变冷却特性分析

采用温度法模型对高温熔融高炉渣颗粒的相变冷却特性进行了分析,考虑颗粒固液相热导率随温度的变化及颗粒与环境的辐射换热,获得了高温熔渣颗粒内的温度分布以及相界面位置随时间的推移过程。讨论了变热导率、换热条件、颗粒尺寸,冷却流体速度和温度对相变冷却过程的影响,结果表明：热导率的变化使得颗粒冷却凝固时间延长,高温辐射换热极大加快了冷却速率;颗粒直径增加,相界面移动速度降低,凝固时间增加;冷却流体速度增加,温度降低,相界面移动速度增加,凝固时间缩短。     

内冷控制技术在吹塑薄膜机组中的应用及发展

介绍内冷控制技术在吹塑机组中得到广泛应用,冷却效果较好,吹膜质量稳定,整机性能大大提高,并经过第二代、第三代的改进日趋完善。     

Numerical Simulation for Effects of Injection Mold Cooling on Warpage and Residual Stresses

Abstract

The dimensions quality of the injection‐molded parts is the result of a complex combination of material, part, and mold designs and process conditions. In this article, warpage prediction relies on the calculation of residual stresses developed during the molding process. The solidification of a molten thermoplastic between cooled parallel plates is used to model the mechanics of part warp in the injection‐molding process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The warp and residual stresses numerical simulation with finite element method (FEM) is time dependent. At each time step, the material properties can be temperature and pressure dependent. Mold temperature or mold‐cooling rate effects on part warp have been numerically predicted and compared with experimental results. By showing the mold‐cooling effects, it was concluded that mold cooling has a significant effect on part warpage, and mold‐cooling parameters, such as mold temperature, resin temperature, cooling channels, etc., should be set carefully.     

Molecular,rheological, and crystalline properties of low‐density polyethylene in blown film extrusion

The molecular weight and its distribution, degree of long chain branching and cooling rate strongly influence crystallinity during processing, which in turn determines the processability and the ultimate properties of the blown film. Generally a decrease in the number of branches and molecular weight of the polymer and the cooling rate results in an increase of the crystallinity. Length of the main chain and extent of branching in low‐density polyethylene (LDPE) are also factors that affect melt rheology and film crystallinity. Long chain branched polyethylene is suitable in the blown film process due to its better melt strength for bubble stability. The objective of this article is to describe the effect of molecular properties (e.g. molecular weight and its distribution, degree of long chain branching etc) of LDPE on film crystallinity at different cooling rates of blown film extrusion. Two different grades of LDPE were selected to investigate molecular characteristics, crystallinity, and rheology. The resins were processed in a blown film extrusion pilot plant using four different cooling rates. Molecular, rheological, and crystalline properties of the resins were key parameters considered in this study. POLYM. ENG. SCI., 47:1983–1991, 2007. © 2007 Society of Plastics Engineers     

Cooling and Solidification of Melted Drops in an Immiscible Cooling Medium

The cooling and solidification of melted drops during their movement in an immiscible cooling medium is widely employed for granulation in the chemical industry, and a study of these processes to provides a basis for the design of the granulation tower height and the temperature of the cooling medium is reported. A physical model of the cooling and solidification of the drop is established and the numerical calculation is performed. The influences of the key factors in the solidification, i.e., Bi number, drop diameter, temperature of the cooling medium, etc. are presented. The cooling and solidification during wax granulation in a water‐cooling tower and during urea granulation in an air‐cooling tower (spraying tower) are described in detail. Characteristics of the solidification and temperature distribution within the particle at different times are shown. The model and calculations can be used for structure design of the granulation tower and optimization of the operation parameters.     

汽车档位杆注塑模具冷却系统设计及优化

由于汽车档位杆属于薄壁中空零件,且采用的是收缩率较大的POM材料进行注塑成型,上、下模具和4个侧面抽芯方向的形状差异较大,因此,各个模具组件之间的温度梯度较大,在注塑成型过程中,经常会发生充填不足和缩水变形等工艺缺陷问题。针对塑件的结构特点设计了多层次的模具冷却系统,使复杂侧抽芯部件得到充分均衡的冷却,在细长抽芯内部设置螺旋隔片使细长抽芯零件也能够得到同步冷却,减少凝固结晶产生的应力,避免零件的翘曲变形和关键部位尺寸精度产生缺陷。应用模流分析技术对注塑过程中各层次的冷却回路工作情况进行数值分析,改进冷却系统结构,提高产品质量并缩短生产周期。     

Transport of a passive scalar across a protective wall-jet in a pipe. Part I: Data acquisition

A wall-jet of a different fluid (or the same fluid at a different thermodynamic state) is blown along the inner surface of a pipe to prevent a contact between the main central flow and the pipe wall. Although motivated by problems encountered in measuring radioactivity, the analogy between heat and mass transfer was utilised for the experiments and concurrent numerical computations which investigated transport of heat from the central air flow towards cool pipe wall, across the protective cool air wall-jet. Similar protective cooling of walls may be actually itself an important application. Another one may be segregation required due to gas chemical aggressiveness. This first part discusses the details of the experiment and the character of the temperature and flow fields evaluated from measured profiles of time-mean velocity and temperature. Analysis of the data, using mutually supporting information from the experiment as well as the computations, is handled in the next, second part.     

三层共挤复合宽幅吹塑棚膜机组的膜泡内冷装置应用效果

简要述及了有吹塑膜泡内冷装置与外冷装置相结合冷却系统的三层共挤复合宽幅吹膜机组的应用。     

On-line ultrasonic monitoring of the injection molding process

On-line ultrasonic monitoring of injection molding of a simple polymer box is studied using pulse-echo techniques. The flow front of molten polymers inside the mold has been probed by a multiple-channel probing system with a time resolution of 2 ms. This information can be used to control the plunger movements. The gap development, because of the shrinkage of the part in the mold, is also monitored. This information, which is important for the understanding of the part's cooling process, has been found to be superior than that measured by a conventional pressure probe. The relation between the gap formation time and the packing pressure has been investigated at various part locations characterized by different thicknesses. The velocity and the amplitude variations of ultrasonic waves, in a reflection as well as in a transmission configuration, have also been measured in the part's material during its solidification. The behavior of these ultrasonic parameters contributes to the interpretation of the solidification process.     

大方钢坯连铸二冷区传热与凝固过程数值模拟

采用改进的波动冷却法(FCA-I)对大方坯连铸二冷区传热与凝固过程进行数值模拟,并与单调冷却法、波动冷却法(FCA)的计算结果进行比较. 结果表明,3种方法计算所得铸坯矫直前温度及液芯长度均与实测值相近,但FCA-I法计算结果更准确,可实时预测拉速变化时铸坯表面温度分布与液芯长度变化. FCA-I法既保留FCA法能准确反映铸坯足辊间温度、凝固壳厚度变化的优点,同时也克服了其难以适应变拉速的缺点. FCA-I法模拟所得结晶器内和二冷区凝固壳厚度dshell与凝固时间t的关系分别满足dshell=19.62t1/2-2.52和dshell=29t1/2,模拟值与文献结果基本一致.