微细发泡注塑成型工艺与微泡尺寸的关系

以数值模拟作为实验手段，工艺参数对微泡长大的影响的判断则采用田口实验方法来进行；结果得出各工艺参数对微泡尺寸的影响次序由大到小为：熔体温度、初始填充量、注射时间、模具温度。在此基础上，进一步研究了各个工艺参数对微泡长大的影响，得出适当降低熔体温度和提高初始填充量可以优化微细发泡注塑制品的微泡尺寸；而注塑时间和模具温度对微泡尺寸的影响不大。     

PLA/PBAT/PTFE原位成纤复合材料微孔发泡行为及性能

采用挤出共混和发泡注塑成型工艺制备了聚乳酸/聚对苯二甲酸-己二酸丁二醇酯/聚四氟乙烯(PLA/PBAT/PTFE)微发泡原位成纤复合材料。研究了PTFE微纤对复合材料的流变性能、泡孔形态以及力学性能的影响,并对泡孔形态与力学性能之间的关系进行了探讨。结果表明,PTFE的引入使复合材料熔体的储能模量和复数黏度升高,发泡材料的泡孔尺寸下降、泡孔密度提高,泡孔形貌得到了改善。随着发泡效果的优化,材料的力学性能也得到了提高。     

Taguchi正交实验技术在微孔注塑中的应用

基于CAE,应用Taguchi正交实验技术,采用变量分析研究了微孔注塑成型工艺参数（塑料熔体温度、模具温度、超临界流体含量,以及熔体预注射量）对微孔注塑件泡孔尺寸的影响,找出其中影响较大的因素作为重点关注对象,从而为实现优化工艺、改变泡孔尺寸、改善制品质量提供有价值的参考。     

微注塑成型技术研究进展

微注塑成型与传统成型有很大的区别,其对成型材料、成型工艺及成型设备等方面都提出了不同要求。现有很多成熟的注射成型技术和理论并不适用于微注塑成型,必须在理论和实践上对微注塑成型的特点进行系统和彻底的研究与探讨。     

微注射成型技术的最新进展

从微注塑设备、成型模具、成型材料、成型工艺控制以及质量表征等方面综述了微注塑技术的最新进展,并对微注塑技术的发展趋势作了展望.     

泡孔结构参数对微孔发泡HIPS力学性能的影响

在不同工艺条件下用化学注射成型制备了微发泡高抗冲聚苯乙烯(HIPS),分析了泡孔结构参数对HIPS力学性能的影响。结果表明,小的泡孔尺寸、泡孔密度和一致的泡孔尺寸分散度都能增强微孔发泡HIPS材料的力学性能。     

复合材料小尺寸螺栓的成型工艺方法探讨

复合材料螺栓已经广泛应用到汽车、航天、航空等各个领域,其中小尺寸螺栓的热塑性注塑工艺成型方法也比较成熟,但热固性模压工艺成型的方法还处于研究阶段,本文通过对热塑性注塑成型的工艺方法和热固性模压成型的工艺方法的对比,阐明热固性模压成型的工艺方法的优、劣势,并对热固性模压成型的工艺方法进行分析和探讨。     

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。     

工艺参数对输液瓶瓶坯注塑性能的影响分析

基于传热学和塑料加工流变学理论,建立熔体在模具型腔中流动的数学模型,对聚丙烯(PP)250 mL输液瓶瓶坯注塑工艺参数对注塑成型性能的影响规律进行了研究。根据正交试验原理,建立由熔体温度、保压压力、模具温度和保压时间等工艺参数共同作用的正交试验,利用Moldflow软件对输液瓶瓶坯的成型过程进行流动模拟,并通过极差分析法和方差分析法获得了最优工艺参数组合。并在此条件下进行试模检验,得到的瓶坯品质合格,尺寸满足公差要求。     

工艺参数对微孔注塑PC制品泡孔形态的影响

采用正交试验法研究了微孔注塑成型工艺参数(熔体温度、模具温度、注射速度、超临界流体(SCF)比例、背压和预塑量)对制品不同截面泡孔密度、泡孔直径的影响。结果表明:影响泡孔尺寸和泡孔密度的主要因素是SCF比例和背压;优化后的工艺组合为熔体温度290℃、模具温度60℃、注射速度70 cm~3/s、SCF比例0.6%、背压15 MPa、预塑量29 cm~3。     

基于计算机仿真的注塑成型工艺优化研究

为了优化注塑成型工艺,研究了注塑成型的数学模型,以及产生翘曲形变的原因,在此基础上利用Moldflow软件对薄壁件塑料注塑成型过程中的宽浇口平板进行了仿真实验,并采用了无定型塑料丙烯腈-丁二烯-苯乙烯共聚物+聚碳酸酯(ABS+PC)对其进行注射、保压、冷却等流程模拟,选定了保压压力、熔体温度、冷却时间、模具温度、注射时间、保压时间等主要工艺参数,并通过方差比较的方法对这些工艺参数进行了评价,最终确定了注塑成型的优化方案。通过实验得出了ABS+PC的最优工艺参数组合,有效降低薄壳制件的翘曲量并优化了其制品性能。     

轿车后视镜外罩成型模拟研究

基于流体运动的基本理论，建立了塑料熔体填充流动的数学模型，利用Moldflow软件对轿车后视镜外罩进行了模拟仿真，分析了壁厚、浇口位置、流动平衡、流动前沿温度、熔接痕以及气穴位置等对成型结果的影响，为模具设计、注射工艺的确定提供了量化指导。     

一步法注射成型注射压力实验分析与建模

通过实验,研究了螺杆转速、注射温度、胶料种类、喷嘴直径等参数对注射压力的影响。对实验因素和实验结果进行了统计分析,确定了各因素的显著水平,并建立注射压力与各参数之间的定量计算的数学模型。     

三维非等温非牛顿流体充模过程的建模与模拟

为了避免使用速度延拓法处理自由表面边界条件,更真实地反映非牛顿熔体的充模过程,耦合Navier-Stokes方程组,建立了三维实体气液两相流模型。采用基于SIMPLE算法的同位网格有限体积法求解流场物理量,并结合Level Set界面追踪技术实现了非等温熔体充模阶段的动态模拟。为防止出现三维情形下棋盘型压力场,利用同位网格动量插值技术,解决压力与速度失耦的问题。分析了充模过程中,流场物理量的变化情况,研究了注射速率、入口温度等对充模过程及熔体凝固层厚度的影响,得出了与实验相吻合的模拟结果。数值结果表明,三维实体气液两相流模型能更准确地描述聚合物熔体的充模过程;当注射速率较大、入口温度较高时,充模时间较短,熔体凝固层的厚度较小。     

Theoretical and visual study of bubble dynamics in foam injection molding

This article presents an experimental observation and a theoretical prediction of bubble dynamics in foam injection molding process with a main focus on the cell collapse phenomenon under pressure. Using a visualizing setup, cell growth behavior under a nonisothermal condition was monitored. In conjunction with the growth behavior, dynamics of cell collapse under different pressures and the effect of growing time on collapse behavior and final cell size were studied. Theoretical simulation of bubble behavior included power law model, which predicted bubble dynamics during foaming process. The results show that collapse phenomenon strongly depends on both exerted holding pressure and growth time. The presented model can also give a reasonable prediction of growth and collapse of cells and could give insight to control of cell size in injection foaming process. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Effect of injection molding parameters on properties of cross-linked low-density polyethylene/ethylene vinyl acetate/organoclay nanocomposite foams

Injection molding of foam articles has always attracted much interest because of elimination of sink mark, good dimensional stability and reduced production cost. In this study, the nanocomposite samples based on low-density polyethylene/ethylene vinyl acetate/organo montmorillonite were processed into foams by injection molding method. Nanocomposites were prepared by co-rotating a twin-screw extruder. The experimental design was based on Box?CBehnken method and parameters such as injection rate, mold temperature and nanolayered silica content were examined in relation to physico-mechanical properties of foams using response surface methodology. Three levels of injection rate (30, 60 and 90?mm/s), nanoclay content (0, 3 and 6?phr) and mold temperature (160, 175 and 190?°C) were chosen. The mathematical model and response surface graphs were employed to illustrate the relationship between the variable parameters and foam properties. The results revealed that the cell size and cell density as the main characteristics of the foams were affected by all parameters. Cell density of samples was affected by mold temperature, injection rate and nanoclay content. At high level of nanocontent the increase of injection rate was accompanied by decreases in density. Tensile strength and specific compression modulus of samples passed through a maximum versus mold temperature due to competition between cross-linking reaction and cell growth. At high mold temperature and injection rate, the cell rupture occurred because of low viscosity of the compounds at these conditions.     

Mathematical modeling and numerical simulation of cell growth in injection molding of microcellular plastics

A mathematical formulation and numerical simulation for non‐isothermal cell growth during the post‐filling stage of microcellular injection molding have been developed. The numerical implementation solves the energy equation, the continuity equation, and a group of equations that describe the mass diffusion of dissolved gas and growth of micro‐cells in a microcellular injection molded part. The “unit‐cell” model employed in this study takes into account the effects of injection and packing pressures, melt and mold temperatures, and super‐critical fluid content on the material properties of the polymer‐gas solution and the cell growth. The material system studied is a microcellular injection molded polyamide 6 (PA‐6) resin. Two Arrhenius‐type equations are used to estimate the coefficients of mass diffusion and solubility for the polymer‐gas solution as functions of temperature. The dependence of the surface tension on the temperature is also included in this study. The numerical results in terms of cell size across the sprue diameter agree fairly well with the experimental observation. The predicted pressure profile at the sprue location has also been found to be in good agreement with the dynamics of the cell growth. Whereas for conventional injection molding the pressure of the system tends to decay monotonously, the pressure profile in microcellular injection molding exhibits an initial decay resulting from cooling and the absence of packing followed by an increase due to cell growth that expands the polymer‐gas solution and helps to pack out the mold uniformly. Polym. Eng. Sci. 44:2274–2287, 2004. © 2004 Society of Plastics Engineers.     

Modeling of the production of ultra fine Aluminium particles in rapid quenching turbulent flow

A two-dimensional axi-symmetric turbulent model of a particle generator with radial injection of a quenching gas was developed to gain a better understanding of the particle forming process. The model uses the Jones–Launder Low Reynolds Number (LRN) Turbulence model to calculate the fluid flow field. The evolution of the particle size distribution is calculated using the method of moments (MOM) assuming a lognormal particle size distribution and no coagulation when the gas temperature is lower than the melting point of Aluminium. The model provides information on distributions of flow, temperature and concentration fields and particle generation within the reactor as well as mixing cup data as a function of reactor length. The effect of the injection flow rate on the characteristics of the final product was studied. The model can be used to study laminar, turbulent and systems where both regimes are present.     

硫酸分解织金含稀土磷矿化学反应过程实验研究

根据湿法制磷酸工艺,采用工业硫酸分解织金含稀土磷矿,研究了反应温度、磷矿粒度和硫酸浓度对贵州织金含稀土磷矿分解率的影响。反应温度为338~348 K,磷矿粒度为0.110~0.075 mm和硫酸的浓度为22.0%~25.0%的条件下,用粒径不变的缩芯模型来描述工业硫酸分解织金含稀土磷矿化学反应过程。推导出了该过程的理论模型和实验数据的回归模型,方差分析表明模型可靠。为工艺条件的优化和反应器的设计提供了理论依据。