塑料成型工艺及模具设计技术问答

内容简介：本书以问答的形式，全面介绍了常用塑料成型工艺及模具设计制造方面的知识和技能。全书共分塑料概论、塑件的设计、注射成型工艺与成型设备、注射模设计、压缩成型工艺与模具设计、传递成型工艺与模具设计、挤出成型工艺与模具设计、其他成型工艺与模具设计、     

金属粉末注射成型工艺

将现代塑料注射成型技术引入粉末冶金领域，不但扩大注射成型技术的应用，同时也推动粉末冶金工艺的发展。详细讨论金属粉末注射成型工艺及其应用，对其材料选择，产品与模具的设计、注射成型工艺过程及烧结工艺过程进行了系统的分析，并展望了该工艺中金属粉末、粘结剂、注射成型装备和工艺过程数值模拟软件等方面的发展趋势。     

陶瓷材料成型工艺研究新进展

陶瓷制造经历数千年历史，当前阻碍陶瓷材料进一步发展的关键之一是成型工艺技术没有突破。本文介绍了胶态成型，固体无模成型工艺及气态成型，对上述工艺的原理、工艺过程及特点进行比较，提出了陶瓷成型工艺的关键问题。并介绍了水基非塑性浆料的注射成型新工艺。     

加成型液体硅橡胶注射成型工艺

文中综述了加成型液体硅橡胶的注射成型工艺，介绍了液体注射成型工艺、共注射成型工艺和气体辅助注射成型工艺及冷流道技术在液体硅橡胶中的应用。     

树脂膜渗透(RFI)成型工艺及其应用

概述了树脂膜渗透(RFI)成型工艺的基本原理、工艺特点、及其纤维预成型体的制作和树脂膜等的关键技术和成型工艺方法及应用，作为一种新型的低成本复合材料成型工艺，其应用市场潜力巨大。     

陶瓷现代成型技术的研究进展

分析了成型工艺在陶瓷制备中的重要作用和高质量的陶瓷坯体对成型工艺的基本要求，评述了国内外陶瓷现代成型技术，着重介绍了离心沉积成型、电泳沉积成型、离心注浆成型、注射成型、胶态成型和快速自动成型等新工艺，讨论了上述成型方法的基本原理和特点，指出了陶瓷成型技术的发展思路。     

硬质聚氯乙烯注射模塑工艺研究

介绍了硬质PVC树脂的注射成型技术，探讨了原料、成型模具、成型设备对工艺的影响及成型工艺条件的控制。     

治理沥青成型系统环境污染的工艺变革

通过对国内现有沥青成型工艺的研究，对比了传统的链板机成型工艺和水下成型工艺的优缺点．对国外的技术进行了了解。重点介绍热袋包装工艺，该工艺能减少煤沥青成型时烟气的排放，很好地解决煤沥青的夏季储存、运输问题，改善现场环境，提升产品品质，方便用户的使用，是我国技术人员对煤沥青成型包装的有益探索，值得在煤焦油加工设计中进行推广。     

挤出吹塑中空成型工艺参数的多目标优化

以挤出吹塑中空制品品质（制品壁厚分布、制品质量）和生产效率为最终的优化目标，成型工艺参数为设计变量，基于混合人工神经网络和遗传算法建立了挤出吹塑中空成型工艺参数的多目标优化系统。此方法不仅可确定满足实际生产需要的初始成型工艺参数，减少用于确定初始成型工艺参数的时间，而且为挤出吹塑中空成型的工艺参数的确定提供了理论依据，为挤出吹塑中空成型生产的全自动化的实现奠定了基础。     

洗衣皂真空出条工艺和冷却出条工艺的技术经济对比

目前，我国洗衣皂成型主要采用冷板成型，真空出条成型和冷却出条成型三条工艺路线。冷板成型，历史悠久，工艺成熟，目前国内大多数肥皂厂均采用这条工艺。尽管冷板成型具有电耗小，松香加入量多，能生产低含量脂肪酸型号的肥皂等优点，但冷板皂产品质量差（肥皂中δ-相含量较多），冷却成型劳动强度大，工作条件恶劣，无法进行连续生产，与社会主义建设事业的蓬勃发展很不适应，迫切需要加以改造。解放以来，虽然广大肥皂工人、技术人员对冷板成型工艺和设备进行了很多革新和创造，提高了冷板成型工艺的水平，但是要想完全摆脱繁重的体力劳动，困难很大。因此，甩掉冷板，筹建连续成型设备，成了我国肥皂工业面临的一项重大任务。     

水辅助熔体充模流动的熔体流痕

构建了用于研究水辅助熔体充模的仿真模具,采用红色和绿色着色剂作为示踪剂,通过水辅助着色的聚丙烯(PP)熔体在柱状模腔里充模,获得了能够反映熔体流动痕迹的样品。通过观察流痕,对水作用下熔体的充模流动进行了研究。实验结果表明:在一次穿透中,与注水喷嘴接触的高黏度熔体造成水从喷嘴射入熔体的不稳定,水的穿透导致模壁附近熔体可能产生回流现象,回流沿水的穿透方向呈减弱趋势。在二次穿透中,水前缘熔体黏度和黏度分布对水的穿透影响较大,熔体体积的收缩是近似线性的减小过程,熔体的剪切流动弱于一次穿透。实验中还发现,水前缘的熔体也会产生"喷泉流"。     

熔体温度对水穿透行为影响的可视化研究

利用水辅助注塑可视化模具和自主研发的注水系统,以聚苯乙烯(PS)为原料,对不同熔体温度下的水辅助熔体流动充模的过程进行了观察,并研究了水的穿透行为。结果表明：熔体温度低,水前缘熔体的惯性力增大,产生"折线"水道,水在后半模腔熔体的穿透中,水前缘速度与水前缘熔体速度相近;熔体黏度高,水前缘速度大于水前缘熔体速度;熔体温度越高,射流穿透的时间越长,水在前半模腔穿透用时越少。     

Melt strength of polypropylene: Its relevance to thermoforming

The melt strength of homopolymer, copolymer and high melt strength (HMS) grades of polypropylene (PP) was measured to assess the sagging resistance of PP for thermoforming applications. Acrylonitrile-butadiene-styrene (ABS), which can be easily processed during thermoforming, was also studied in this work. A polymer with high melt strength is considered to have a better sagging resistance. The melt strength measurements were carried out using a Gottfert “Rheotens” melt strength tester. The melt strength of the polymers increased with decreasing temperature and increasing extrusion rate. ABS generally had the highest melt strength in the low extrusion temperature region approaching the thermoforming region, indicating that it has a good sagging resistance during thermoforming. The HMS PP had significantly higher melt strength than conventional PP grades; therefore HMS PP is expected to have an improved sagging resistance. For conventional PP, melt strength was higher for the lower melt flow index (MFI) grades. A sharp increase in the melt strength was observed for conventional PP at low extrusion temperature, probably due to flow-induced crystallization of the PP. These results indicate that to minimise the sagging problem with conventional PP, low MFI grades should be used and thermoforming should be performed at temperatures close to the melting point of PP.     

聚合物振动注射成型熔池增强方法的研究

利用同一副模具上有熔池和无熔池实验样条，在振动实验机上进行振动注射实验，低频振动下有熔池和无熔池祥条在振动注射成型时，其拉伸屈服强度是不同的，增加熔池，聚合物的拉伸屈服强度有较大提高。振动频率存在一个最佳值，超过此值后，拉伸屈服强度会逐渐走低并接近无振动状态下的拉伸屈服强度。     

一种新型聚合物熔体动态密度测量方法的研究

介绍一种聚合物熔体在不同温度及压力状态下熔体密度的测量方法,该方法基于聚合物熔体PVT相互关系原理,将测量微距离的读数百分表安装在改进结构的熔体流动速率试验机上,可以测量出任意熔融温度及压力下的聚合物熔体密度。通过对测量结果进行理论分析发现,聚合物熔体密度测量值符合聚合物自由体积理论,即聚合物熔体密度随温度升高而减小,随压力增大而增大。     

Effect of process variables on melt temperature profiles in extrusion process using single screw plastics extruder

Abstract

Melt temperature is an important parameter in the melt processing of polymers. However, it is not possible to control melt temperature directly, only to influence it using processing parameters such as processing temperature settings. It is therefore important to know the influence of controllable process parameters on melt temperature. In this work, the relationships between controllable process parameters and melt temperature have been investigated for a 50 mm S + B single screw extruder. The extruder was equipped with a thermocouple mesh at the die inlet to determine melt temperature. It was found that melt pressure, die size, feed section barrel temperature, and compression section barrel temperature had a negligible effect on the melt temperature profiles generated, while increasing the screw speed resulted in higher melt temperatures. The metering section barrel temperature had a significant effect on melt temperature, thermal conduction effects being more important than shear heating effects. Equipment wall temperatures, downstream of the screw, produced changes in the melt temperature in the melt located within 7 mm of the wall. It was found that melt temperatures can be significantly different from those set on the equipment.     

Melt strength and extensibility of talc‐filled polypropylene

Polypropylene homopolymer melts containing up to 50 percent by weight of talc filler (24 vol%) were tested on a Gottfert Rheotens melt strength testing unit. Melt strength and drawability parameters were measured from these tests to evaluate changes in the extensional behavior of the melt induced by filler addition. It was found that the melt strength of the polypropylene was decreased for talc additions of less than 40 wt% (17.5 vol%) under all test conditions. Addition of 50 wt% talc improved the melt strength under all testing conditions. Drawability, defined as the stretch ratio at strand break, decreased with increased filler loading. The melt strength of all materials was found to decrease with increased temperature within the range 180°C to 210°C. The melt strength of all melts showed dependence on the test extrusion rate, and this dependence was well described by an exponential relationship. Highest dependencies were seen for the unfilled and 50 wt% talc‐filled polymer. While it was found that addition of 50 wt% talc provided improvement in melt strength, high melt strength alone was a poor indicator of the melt processability, as drawability was also regarded as an important consideration.     

用于发泡成型的高熔体强度聚丙烯的研究

在同向双螺杆挤出机上,对聚丙烯(PP)进行硅烷交联,制得高熔体强度聚丙烯(HMSPP),然后制备高发泡倍率的PP制品。分析了改性剂用量对PP熔体流动速率、熔体黏度、熔体强度、凝胶含量、力学性能、热性能和发泡性能的影响。结果表明:自制HMSPP的熔体强度和熔体黏度分别是纯PP的5.01倍和1.52倍,力学性能和耐热性与纯PP相比均有较大提高,可用于成型高发泡倍率制品。     

The Formula for Apparent Viscosity of Polymer Melt Extruding Through a Capillary Under a Superimposed Vibration

The apparent viscosity of a polymer melt within a capillary was analyzed based on experimental measuring when a sine vibration of small amplitude was superimposed in a parallel manner on the extruding direction of polymer melt. The theoretical model for apparent viscosity of polymer melt under an superimposed vibration was set up independent of any existing constitutive equations. Meanwhile, the calculating steps for previously apparent viscosity were established by making use of novel rheological measurement equipment that was designed by the author. Through collecting and analyzing the instantaneous data of a polymer melt dynamic extruding through a capillary under definite frequency and amplitude of vibration, the apparent viscosity of a polymer melt within a capillary was then calculated.     

注气口前后段螺杆中聚合物熔体的数值研究

运用Polyflow软件对微孔塑料挤出成型过程中注气口前后段螺杆进行三位瞬态模拟,研究了不同聚合物黏度、不同螺杆转速下注气口处的熔体压力场及熔体质量流量。结果表明,沿轴向640~670 mm处最符合作为超临界气体注入口的工艺条件;注气口处熔体压力在径向范围变化幅度不大,只需在注气口处所注入的超临界气体压力略大于熔体压力即可;随着螺杆转速的增大,注气口处聚合物熔体质量流量也随之增加,且两者之间呈现规律性变化,故可得到在不同螺杆转速下聚合物熔体质量流量大小。