熔接痕位置预测及优化技术研究进展

综述了熔接痕位置预测、优化和控制技术的研究进展,介绍了填充过程熔接痕形成的数学模型。对数值模拟技术、数值模拟技术结合数学规划理论、阀式浇注和大型注射成型制品多浇口进料顺序控制技术等3种技术的分析流程、预测方法和应用实例进行了详细介绍,其中基于数值模拟技术和数学规划理论结合的熔接痕位置确定新算法是行之有效的熔接痕位置优化技术,已成为当前研究热点。随着该技术的日趋成熟,应用范围将逐渐增大。而阀式浇注和大型注射成型制品多浇口进料顺序控制技术的实施可以成功避免注塑件熔接痕的出现,在大型零件生产中具有广阔的应用前景。     

注塑件熔接痕的研究进展

介绍了注塑件熔接痕的形成机理,分析了影响熔接痕强度的各种因素,从注塑工艺参数设定、模具结构设计等方面给出了消除熔接痕或提高熔接痕强度的措施。     

纤维增强PA66注塑熔接痕性能的工艺优化

针对注塑过程中纤维增强PA66制品出现的熔接痕缺陷,利用Taguchi方法设计了L9实验矩阵,分析了注塑压力、熔体温度、注射速率和保压压力等工艺因素对注塑件熔接痕拉伸强度的影响,预测了最大拉伸强度和最佳工艺条件,与实验结果具有很好的一致性。     

应用模内局部加热改善ABS/Al粉共混注塑件的熔接痕

针对Al粉与聚合物共混注塑时熔接痕和流痕的形成特点,提出了采用型腔局部加热技术改善共混物制件熔接痕的新型工艺方法;并通过实验验证了该新型工艺方法对塑件熔接痕的影响。结果表明:采用局部加热技术能有效改善或减少熔接痕,随着加热温度的升高,注塑件的表面光泽度明显提高,熔接痕也得到了一定的改善。     

变模温控制技术改善注塑制品熔接痕的研究

阐述了变模温技术理论,借助CAE数值模拟仿真平台对翻盖手机外壳注塑成型过程进行动态模拟,对传统注射工艺和变模温注射工艺产生的熔接痕进行了详细的比较和分析。结果表明:相比传统的恒定模温控制,变模温控制技术对塑件熔接痕的改善效果更加明显,提高了熔接强度,优化了熔接痕,在不影响生产效率的基础上,达到了提升制品品质的目的。     

工艺参数对注塑件熔接痕性能的影响

概述了注塑件熔接痕的分类及特点；分析了工艺参数主要包括熔体温度、模具温度、充模速度、注射时间、注射压力、保压压力、后处理等对熔接痕的外观及性能的影响。着重阐述了各工艺参数对熔接痕性能影响的研究进展；综述了优化工艺参数和研究工艺参数对熔接痕影响程度的研究以及数值模拟技术，并从工艺方面提出了减小熔接痕损害的方法。     

基于神经网络汽车门把手的注塑工艺参数优化

针对汽车门把手在企业生产过程中存在的具体问题,采用数值模拟技术、正交试验设计理论和神经网络理论优化塑件的注塑工艺参数,获得较为准确的最佳工艺参数组合,提出新的预测塑件熔接痕长度和位置的方法.新技术和新思路的运用,在控制汽车门把手熔接痕方面产生了良好的效果.     

顺序控制技术在轿车前保险杠注射成型中的应用

针对传统注射成型汽车保险杠生产中存在熔接痕数目多、在涂装过程中频繁出现色差等问题,提出了顺序控制注塑技术的新方法,即在原有注塑机热流道基础上加装可控制的液压回路来实现多浇口顺序控制,从而减少或消除熔接痕。通过数值模拟技术对某轿车前保险杠注射成型过程进行数值模拟,将其结果与传统注射成型方法进行了比较,结果表明采用顺序控制注塑技术不仅能消除保险杠中的熔接痕,而且还能优化其它生产工艺,对保险杠的生产具有实际意义。     

注塑件熔接痕强度预测及提高新技术

介绍了注塑件熔接痕强度预测及提高的几种新技术。综述了基于扩散理论和Flory—Huggins晶格理论的预测模型及基于BP神经网络的预测模型。给出了模型的适用范围。简述了热流道多浇口进料顺序控制、注射成型和模具设计等几种提高熔接痕强度、减少或避免熔接痕出现的新技术的作用机理及应用实例,指出进一步完善熔接痕强度预测模型和强度提高技术是今后熔接痕研究的一个重要方向。     

基于MPI软件优化设计注塑制件的浇口位置

针对浇口在注塑制品成型过程中的重要地位,介绍了专业模流分析软件MPI在优化浇口设计中的应用。以某汽车的雾灯支架为例,运用MPI模拟注塑件的整个注射成型过程,从产品的翘曲变形、熔接痕、产品重量和生产周期等方面对不同的浇口位置进行优化设计,最终获得高预测质量的产品。     

半透明注塑制品熔接痕分析及控制对策

借助模流分析软件Moldnow对半透明注塑制品熔接痕位置进行模拟分析,以此来优化浇口的位置和成型工艺参数,最终使熔接痕位于半透明注塑制品不重要的部位,并提高了熔接痕的强度.     

Untersuchung zur Vorhersage der Bindenahtfestigkeit in spritzgegossenen Formteilen

Weld lines in injection molded parts are often weak spots and should therefore be taken into account as early as possible when developing new parts. The influence of material, nozzle and mold temperature respectively injection speed on weld line strength was investigated. By obtaining the actual temperature in the weld line, the interrelated processing influences can be expressed by a common relation. Physical analysis shows that this is the molecular mobility, which in turn is dependent on temperature. It opens a route backed by experimental results to assess the weld line strength of different materials in dependence of the processing parameters.     

Effect of process conditions on the weld‐line strength and microstructure of microcellular injection molded parts

This study was aimed at understanding how the process conditions affect the weld‐line strength and microstructure of injection molded microcellular parts. A design of experiments (DOE) was performed and polycarbonate tensile test specimens were produced for tensile tests and microscopic analysis. Injection molding trials were performed by systematically adjusting four process parameters (i.e., melt temperature, shot size, supercritical fluid (SCF) level, and injection speed). For comparison, conventional solid specimens were also produced. The tensile strength was measured at the weld line and away from the weld line. The weld‐line strength of injecton molded microcellular parts was lower than that of its solid counterparts. It increased with increasing shot size, melt temperature, and injection speed, and was weakly dependent on the supercritical fluid level. The microstructure of the molded specimens at various cross sections were examined using scanning electron microscope (SEM) and a light microscope to study the variation of cell size and density with different process conditions.     

Effect of supercritical nitrogen content on the weld lines and mechanical properties of microcellular injection molded double gate PP/Al parts

Injection molding products made of aluminum flakes and polymer blends exhibit a distinctive esthetic effect. However, during the filling process, the melt flows in different directions converge and collide, resulting in the flop effect of the aluminum flake and consequent weld line formation. Herein, microcellular injection molding (MIM) was employed to fabricate polypropylene/aluminum flakes (PP/Al) composite foamed parts with distinct weld lines using supercritical nitrogen (scN₂) as the physical blowing agent. The scN₂ content has a significant effect on cell diameter and cell density. When the scN₂ content was 0.6%, the weld line width of the foamed part was 13.03 μm, while it was 30.41 μm for the solid counterpart due to the expansion and rupture of cells in the flow front during filling. Moreover, the orientation of Al flakes was mostly along the flow direction for the foamed parts, while it was generally aligned perpendicular to the flow direction for solid parts in the weld line region. In addition, the flexural modulus of foamed parts was increased by 29% compared with the solid parts, although the tensile strength was reduced by 18% due to the alignment of Al flakes and the stress concentration on the cell walls. Therefore, this work provides insight into the improvement of flexural property and the mitigation of weld lines for injection molded composite parts using MIM.     

注塑件成型缺陷分析与解决方案

针对耳罩圈注塑件填充不足和熔接痕的缺陷问题,本文从注塑模具浇注系统分析入手,找出存在的问题,制订出改正措施,并最终解决了这些缺陷问题;在针对使用一模六腔模具成型的护盖注塑件存在缩痕缺陷的问题,通过采用了控制流入模具型腔熔体量平衡的方法,最终达到了消除注塑件缺陷的目的;针对薄壁壳体注塑件变形等缺陷的问题,则采用了脱件板方...     

Evaluation of healing models to predict the weld line strength of the amorphous thermoplastic polystyrene by injection molding simulation

In many injection molded parts weld lines are often unavoidable. These cause optical defects and a reduction of the mechanical properties of the part. Therefore, the predictability of the weld line strength at an early stage of development would provide a significant advantage by avoiding costly iterations of the mold and increases the understanding of the correlation between process history of the melt and weld line strength. For this purpose, a calculation routine has been developed to predict the weld line strength based on injection molding simulation. Different models to calculate the healing of a weld line are compared and analyzed. By adding a factor to consider the shear rate in addition to the temperature and the pressure and after calibration to one design of experiment setting of the experimental data, the prediction of the weld line strength shows good agreement for all examined process setpoints of the experimental data for polystyrene.     

基于Moldflow的汽车盒体件注塑模具设计

分析了汽车盒体塑件的成型工艺,通过Moldflow软件对熔体的填充时间、注射压力、熔体前沿温度、气穴及熔接痕位置等进行了分析,根据模拟分析结果设计了一副三板式潜伏式浇口注塑模具,并对模具进行了合理的选材和热处理。结果表明,模具设计合理,运动平稳,成型的塑件尺寸精度高,表面无飞边、熔接痕、气穴等质量缺陷。     

车载蓝牙外壳高光无痕注射CAE分析及参数优化

以车载蓝牙外壳为例,研究了局部密孔制件与普通制件高光注射成型的区别。利用Moldflow软件结合正交方法、数值模拟和数据处理技术,对高光无痕注射成型工艺进行了模拟分析。针对高光成型指标(翘曲变形、体积收缩率和熔接痕),研究了模具温度对高光制品品质的影响,得出高光制品品质随温度的升高而改善。并在此基础上模拟了熔体温度等多因素对高光制品体积收缩率和翘曲变形的影响,优化了工艺参数。     

注射模浇注系统对成型工艺和塑件质量影响研究

通过筒形结构的塑件CAE模拟分析,设置不同的分流道的形状,浇口形状、位置和数目,研究对于流动、填充时间、最大注射压力、最大锁模力和熔接痕等成型工艺和塑件质量的影响。