三维注射成型流动模拟的研究

介绍了一种基于三维模型的注射成型流动模拟的数学模型和数值实现，把速度和压力同次插值方法成功地应用到三维注塑模拟的计算中，从离散的动量方程中找出压力和速度的关系，然后代到连续性方程中得到压力方程。用三维控制体积法追踪流动前沿，并通过算例分析来说明三维模型的有效性。     

注塑模温度场的计算机模拟

本文运用有限元法，采用二次等参单元，对注塑模二维非稳态温度场进行了数值分析，推导了有限元数值求解方程并研制了有限元求解程序软件。实例所得温度场等温线与实验所得结果基本相符，验证了计算机求解的可靠性。通过计算机模拟分析，可了解各瞬时模具温度场的分布状态，观察模具体能否使塑件均匀冷却，如不合理，可通过改变冷却管道参数，达到温度场均匀一致，从而提高塑件质量。通过程序运转，根据塑件的热定型温度，可以预知最短冷却时间，从而缩短冷却周期，提高塑件生产率     

Characteristics of mould separation and its effects on qualities of thin wall injection moulded parts

Abstract

Precision injection moulding of thin walled parts has become an important concern in the computer, communication, and consumer electronics plastics industry. Previous studies in precision injection moulding control focus on the injection screw and the associated operations. In the present study, the influence of relevant parameters including injection speed, melt temperature, mould temperature, filling-packing switchover, and packing pressure on the mould plate separation under different clamping pressure were investigated as part of precision moulding control. A two cavity tensile test specimen mould equipped with four linear variable displacement transducers across the parting surfaces of the mould was used. A computer based monitoring system was built to detect the mould separation signals. Mould separation can also be identified from part weight and thickness variation and exhibits relevant correspondence with them. It was found that owing to the high injection speed required for thin wall moulding, mould separation is not negligible. In all situations, mould separation decreases with increasing clamping pressure. As melttemperature andmouldtemperatureincrease,mouldseparationincreases, resulting in an increase in part weight and thickness. Similarly, when packing pressure and injection speed increase, mould separation also increases. Earlier switchover from filling to packing can decrease mould separation as well as part weight and thickness. Among all the parameters studied, packing pressure exhibits the greatest influence on mould separation and on the associated weight and thickness change. This influence also becomes larger when the moulded part becomes thinner, owing to the larger injection moulding pressure. PRC/1746     

Calculation of Crystallization with Injection Moulding Simulation Software based on Three‐Dimensional Approaches

Injection moulding is the most popular process for manufacturing technical plastics parts. The computer simulation of the process is an essential tool to fulfil requirements with respect to part quality and efficiency. Up to now, the entire simulation has been based on two‐dimensional software. Presently, the three‐dimensional software offers new applications to improve the quality of the simulation. As in other groups, research at the IKV deals with the three‐dimensional calculation of crystallization. In a first step, the calculation of thermally induced crystallization based on a three‐dimensional temperature calculation is now available. First results show a good qualitative agreement with experimental studies. For the improvement of the quantitative quality of the simulation results further developments have to be performed.     

高技术陶瓷产品的精密注射成型制备技术的应用与发展

讨论了陶瓷粉末注射成型制备精密陶瓷部件这一新技术及其国内外发展状况。先进陶瓷精密注射成型的科学基础是现代高分子精密注塑理论和现代陶瓷制造技术,它将高分子流变学、陶瓷粉体技术、陶瓷工艺学和金属模具精密制造技术结合在一起。该技术突出的优点有:①可净近成型各种复杂形状的陶瓷零部件,使烧结后的陶瓷产品无需进行机加工或少加工,从而减少昂贵的陶瓷成本;②成型制品具有极高的尺寸精度和表面光洁度;③可实现微成型(Micro Injection Molding),制备μm-mm范围内的微型陶瓷零件;④成型过程机械化和自动化程度高,重复性好,便于规模化低成本生产。该技术已用于陶瓷发动机、通讯产业中光纤连接器插芯(Ferrule)、计算机工业中光盘盒磁盘驱动用陶瓷轴承和生物医学用陶瓷制品等精密陶瓷件的制造。随着微注射成型新技术的发展,微型陶瓷部件将应用于环境要求苛刻、结构复杂的MEMS系统。     

注射成型过程中非牛顿塑料熔体的流变特性

在探讨塑料熔体粘度模型的基础上，根据塑料熔体在注射成型过程中的流动特点，讨论了一种能够在加工温度和压力条件下，剪切速率在l0～10^3s^-1的变化范围内，相当精确地描述高聚物流变特性的拈度模型。重点讨论了模型的参数拟合和适用范围，为注射模具设计和成型模拟提供了科学依据。     

基于注射成型模拟技术的塑料件浇口位置优化设计

针对注塑模具中合理的浇口位置在塑料制品设计中的重要性，提出了在模具设计中采用塑料注射成型模拟技术对塑料件浇口位置进行优化设计的思想。以鼠标上端盖作为实例，介绍了借助模拟分析软件MPI对其浇口位置进行计算机模拟分析的过程，优化了模具的浇口位置及注射成型工艺参数，从而获得了高预测质量的产品，降低了生产成本，提高了模具企业的市场竞争力。     

气体辅助注射成型技术

介绍了消除厚壁制件所出现的缩痕、凹痕缺陷的一种新型塑料成型工艺－－气体辅助注射成型技术的工作原理,技术关键、设备配置及其应用,并重点介绍了内置气体辅助成型和表面气体辅助成型技术。     

注塑件翘曲变形的CAE研究

从注塑成型的角度讨论了与翘曲变形有关的因素，从数值模拟的角度论述了翘曲变形计算机辅助工程（CAE）分析的数学模型和数值算法，最后从应用的角度，说明翘曲变形CAE结果的合理应用。     

基于CAE优化分析的汽车水箱盖中盖注塑模设计

针对汽车水箱盖中盖的结构特征,结合CAE技术对产品进行注塑成型过程模拟分析,确立了点浇口浇注系统并优化了冷却方案,在此基础上完成了注塑模设计。在模具结构设计中,提出用斜滑块和斜顶组合脱螺纹机构代替常用的旋转脱螺纹方式。模具结构合理,运动可靠,产品成型质量好。     

薄壁注塑成型中的变模温控制技术

介绍了薄壁注塑成型中存在的主要问题,阐述了变模温控制技术在薄壁注塑成型中的重要性,综述了当前各种变模温控制技术的原理及其在薄壁注塑成型中的研究与应用进展,并展望了未来薄壁注塑成型中变模温控制技术的发展趋势。     

Experimental study of weldline caused by flow lead effect in gas assisted injection moulded parts

Abstract

Gas assisted injection moulding has become one of the most important methods for the manufacture of plastic products. However, there are several unsolved problems that confound the overall success of this technique. The weldline caused by the flow lead effect in the polymer melt is one of them. In this report, an L′18 orthogonal array design based on the Taguchi method has been conducted to investigate the flow lead induced weldlines in gas assisted injection moulded parts. A plate cavity with a gas channel on the side was used for moulding. Experiments were carried out on an 80 t reciprocating screw injection moulding machine equipped with a high pressure gas injection unit. After moulding, the depth of the weldline was measured. For the factors selected in the main experiments, melt injection temperature and mould temperature were found to be the principal factors affecting the weldline depth of gas assisted injection moulded parts. Experimental investigation of a gas assisted injection moulding problem can help in better understanding the weldlines caused by flow lead effects, so that steps can be taken to optimise the surface quality of moulded parts. PRC/1755     

医用化验瓶热流道注射模设计

介绍了医用化验瓶形状,结构及成型工艺性,在满足用户要求的前提下,分析了普通注射模成型所存在的问题与不足,设计了采用热流注射成型的科学合理的热流道注射模,并论述了模具的主要特点及模具设计中应注意的问题。     

全电子注塑机的合模控制及锁模力的研究

根据连杆机构的运动学原理,推导出全电子注塑机动模板位移与电机位移及动模板速度与电机速度的关系公式,并采用Metlab软件拟合出位移和速度关系曲线,通过这些曲线可以有效地监控全电子注塑机动模板的位置和速度变化,为用户设置模具保护功能提供理论依据.采用粘贴式电阻应变片法对锁模力进行测试,得出了动模板初始位移与锁模力大小的关系公式,保证了注塑过程中锁模力的稳定性.     

Three‐dimensional simulation of multi‐material injection molding: Application to gas‐assisted and co‐injection molding

This paper presents an overview of the results obtained at the Industrial Materials Institute (IMI) on the numerical simulation of the gas‐assisted injection molding and co‐injection molding. For this work, the IMI's three‐dimensional (3D) finite element flow analysis code was used. Non‐Newtonian, non‐isothermal flow solutions are obtained by solving the momentum, mass and energy equations. Two additional transport equations are solved to track polymer/air and skin/core materials interfaces. Solutions are shown for different thin parts and then for thick three‐dimensional geometries. Different operating conditions are considered and the influence of various processing parameters is analyzed.     

注塑模具概念设计的CAE应用

为研究注塑过程模拟技术捕助模具概念设计和工艺设计结合实例分析了 CAE在概念设计阶段的作用,及其进行模具流道系统和冷却系统设计方案的评估和优化的途径,提出了在模具概念设计阶段利用CAE技术捕助助塑工艺设计的方法。结果表明,该方法可以在模具概念设计阶段有效顶测填充模式的合理性、预测特定模具结构及其注塑材料注射成型可能存在的缺陷、确定合理的排气槽位置、对冷却系统的布局和设计合理性进行评价等,是缩短模具开发周期、提高设计品质的有效措施。     

橡胶注射成型技术及其设备

本文论述了目前橡胶注射机主要装置的结构和性能特点．简要介绍了全电动橡胶注射机、气体辅助液态硅橡胶注射技术和橡胶注射模具冷流道技术的进展。     

基于数值模拟的注塑模具优化及注塑成型工艺参数快速设置

以某一监控设备外壳成型为例,介绍了利用Moldflow软件优化模具结构及快速设置注塑成型工艺参数的方法,为注塑模具设计和试模时工艺参数的设定提供了依据,缩短了模具设计和试模周期。     

橡胶注射过程中压力变化的研究

对橡胶注射过程中的压力变化进行了理论与实验研究。充模流动模型的压力、能量控制方程分别为：选用高斯方法求解总体有限元方程。实验与计算分析对比证明．本文选用的数学模型和计算方法所得结果与实测结果基本吻合、该模型可用以代替大量的实验，对橡胶充模过程进行模拟，并用Ｇｒａｐｈｅｒ软件对数值结果进行处理，以图表直观地表达出各种因素对充模过程的影响。     

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。