Injection molding of nano structured 90W-7Ni-3Fe alloy powder prepared by high energy ball milling

Blended elemental 90W 7Ni 3Fe (mass fraction, %) powder was mechanically alloyed in a planetary ball mill. Nano crystalline grains were obtained after 10 h milling. The nano structured powder was processed to full density by metal injection molding approach. Compacts from the optimal powder binder mixture were studied for molding and sintering behaviors. Milling significantly increases the maximum powder loading and homogeneity of the feedstock, and enhances the sintering densification process. When solid state sintered at 1 350～1 450 ℃, the alloy shows very fine grains (～3 μm), high tensile strength (>1 130 MPa) and almost no distortion. [

Effect of Molecular Weight and Molecular Distribution on Skin Structure and Shear Strength Distribution near the Surface of Thin-Wall Injection Molded Polypropylene

In this study, the relationship between skin structure and shear strength distribution of thin-wall injection molded polypropylene (PP) molded at different molecular weight and molecular distribution was investigated. Skin-core structure, cross-sectional morphology, crystallinity, crystal orientation, crystal morphology and molecular orientation were evaluated by using polarized optical microscope, differential scanning calorimeter, X-ray spectroscopic analyzer and laser Raman spectroscopy, respectively, while the shear strength distribution was investigated using a micro cutting method called SAICAS (Surface And Interfacial Cutting Analysis System). The results indicated that the difference of molecular weight and molecular weight distribution showed own skin layer thickness. Especially, high molecular weight sample showed thicker layer of the lamellar orientation and molecular orientation than low molecular weight sample. In addition, wide molecular distribution sample showed large crystal orientation layer.

SPATIAL HIERARCHY AND INTERFACIAL STRUCTURE IN INJECTION-MOLDED BARS OF POLYPROPYLENE-BASED BLENDS AND COMPOSITES

The hierarchical structure and interfacial morphology of injection-molded bars of polypropylene （PP） based blends and composites have been investigated in detail from the skin to the core. For preparation of injection-molded bars with high-level orientation and good interfacial adhesion, a dynamic packing injection molding technology was applied to exert oscillatory shear on the melts during solidification stage. Depending on incorporated component, interfacial adhesion and processing conditions, various oriented structure and morphology could be obtained. First, we will elucidate the epitaxial behavior between PP and high-density polyethylene occurring in practical molded processing. Then, the shear-induced transcrystalline structure will be the main focus for PP/fiber composites. At last, various oriented clay structures have been ascertained unambiguously in PP/organoclay nanocomposites along the thickness of molded bars.

HIGH SPEED INJECTION MOLDING OF HIGH DENSITY POLYETHYLENE—EFFECTS OF INJECTION SPEED ON STRUCTURE AND PROPERTIES

Thin wall samples of high density polyethylene （HDPE） were prepared via injection molding with different injection speeds ranging from 100 mm/s to 1200 mm/s. A significant decrease in the tensile strength and Young＇s modulus was observed with increasing injection speed. In order to investigate the mechanism behind this decrease, the orientation, molecular weight, molecular weight distribution, melt flow rate, crystallinity and crystal morphology of HDPE were characterized using two-dimensional wide-angle X-ray diffraction （2D-WAXD）, gel permeation chromatography （GPC）, capillary rheometry and differential scanning calorimetry （DSC）, respectively. It is demonstrated that the orientation, molecular weight, molecular weight distribution, melt flow rate and crystallinity have no obvious change with increasing injection speed. Nevertheless, the content of extended chain crystals or large folded chain crystals was found to decrease with increasing injection speed. Therefore, it is concluded that the decrease in tensile properties is mainly contributed by the reduced content of extended chain crystals or large folded chain crystals. This study provides industry with valuable information for the application of high speed injection molding.

Effect of film types on thermal response,cellular structure,forming defects and mechanical properties of combined in-mold decoration and microcellular injection molding parts

Different types of polymer films were used in the combined in-mold decoration and microcellular injection molding(IMD/MIM)process.The multiphase fluid-solid coupled heat transfer model was established to study the thermal response at the melt filling stage in the IMD/MIM process.It was found that the temperature distributed asymmetrically along the thickness direction due to the changed heat transfer coefficient of the melt on the film side.When polyethylene terephthalate(PET)films were applied,the temperature of the melt-film interface increased faster and to be higher at the end of melt filling stage in comparison with the application of polycarbonate(PC)and thermoplastic polyurethane(TPU)films.And the effects of film types on the cellular structure,forming defects and mechanical properties of IMD/MIM parts were also studied experimentally.The results showed that the film types had no obvious effect on the cells size in the transition layer and the mechanical properties of the parts.Under certain film thickness,the offset distance of core layer was the largest with PET film used,while the offset distance was the smallest with TPU film used.And similar results were found for the warpage of the parts.However,an exactly opposite change occurred for the thickness of film-side transition layer and the bubble marks on the surface of the parts.

应用Moldflow及ABAQUS进行注塑模结构优化设计

通过运用Moldflow进行模流分析,在产品加工制造前分析成型质量,确定最佳工艺参数和成型条件。结合利用有限元软件ABAQUS进行型腔结构受力变形分析,获取应力在型腔接触面上呈不均匀分布的特性;增加型腔厚度对改善其抗压性减小变形效果明显,但随着厚度增加效果减弱并存在极限值;还获悉模板的变形量随着材料杨式模数的增加为线性递减趋势,为优化注塑模结构设计提供参考。实践证明:在模流软件Moldflow和有限元分析软件ABAQUS的协同环境下设计注塑模具是非常有效且简便的方法。

基于Moldflow与Ansys的碟片盒注塑模具结构分析

探讨了注塑模具结构分析的应用流程与注意事项。以碟片盒注塑模具为例,借助Ansys软件的结构分析功能和Moldflow软件的注射成型分析功能,完成了模具动模部分的结构分析并得到了合理的支撑柱布置方案。研究结果表明,模具结构分析中要遵循"定性分析为主,定量分析为辅"的原则。

基于改进材料和结构融合的仪表板横梁轻量化设计

针对现有钢质仪表板横梁(CCB)重量较重、零件较多、工艺复杂且表面处理会污染环境的问题,提出一种将改进材料和优化结构相融合的全塑仪表板横梁轻量化设计方法。首先依据复合材料的成型工艺要求和CCB的安装环境对CCB进行模型设计,使其实现一体化的目标;然后应用Moldflow模流分析对CCB模型的工艺进行全局验证和寻优;最后,基于HyperMesh有限元分析对全塑CCB力学性能进行验证,结果表明,通过设计优化得到的全塑CCB质量下降了53.5%。

注塑机抽拉杆的有限元分析及疲劳预测

注塑机抽拉杆结构是一种便于在有限厂房空间内实现更换模具的技术。相比较传统拉杆,由于其受力条件更为复杂,故对其材料的机械强度有更高要求。本文采用Creo Simulate的有限元分析工具分别对常用的31CrMoV9V与42CrMo4V两种材料进行应力和变形分析并对其做出疲劳预测,为实际生产提供相关参考依据。

基于MoldFlow的鼠标上盖注射模设计

鼠标上盖为外观件,属薄壁壳体类塑件,注射成型质量较难控制。在结构分析的基础上,对模具进行整体设计,分析了模具工作过程,设计了斜顶机构、司筒机构,有利于实现上盖背面卡扣、柱体的脱模,设计了潜伏式浇口,避免出现浇口痕迹。并对浇注系统、推出机构及冷却系统的设计进行了分析。在设计过程中使用了MoldFlow软件对结构进行分析,对设计方案进行数据分析、对比,迅速得出优化的模具设计方案,省去了试模过程,有效地提高了模具设计效率和设计质量。

MoldFlow软件在梳子注射模结构改进及其成型缺陷分析中的应用

根据梳子注射模在试模过程中存在的一些问题,采用MoldFlow软件进行分析,为改进模具结构、解决其成型缺陷提供有价值的参考。

基于HyperMesh、MoldFlow与Nastran的注塑优化集成

对考虑充模历史情况下的模具结构分析与优化进行了研究,综合运用HyperMesh、Moldflow和Nastran等多种软件完成从几何建模、网格划分、分析计算到结果处理的整个过程,实现了模流分析与模具结构分析的集成优化。结果表明,注射成型工艺与模具结构分析的集成可以更加真实和全面地模拟注塑过程中塑料的流动情况和模具变形情况,为模具设计提供更为全面的参考依据。

基于Moldex3D分析模具温度对PP发泡注塑制品的影响

对微孔发泡注塑过程进行模具温度控制,对制品进行扫描电子显微镜、弯曲强度、冲击强度、表面粗糙度测试,探讨模具温度对制品的力学性能与泡孔结构的影响。结果表明,当其他工艺参数不变时,提高模具温度,制品的泡孔更加致密,有助于提高制品的弯曲性能和冲击性能并且有助于降低制品表面粗糙度;通过Moldex3D模拟统计泡孔平均直径、密度以及尺寸标准差,验证了模具温度升高时,泡孔尺寸标准差降低,泡孔分布更加均匀;通过模拟验证了当模具温度升高时,泡孔尺寸以及制品减重比变化趋势与实验结果一致。

基于Moldflow的电气分线盒成型优化分析

研究了电气分线盒塑件的结构和材料特性,采用Moldflow软件对塑件浇口位置、填充过程、成型窗口、冷却过程等进行模流分析。结果表明:塑件在填充过程中出现质量缺陷的主要原因是塑件壁厚相差过大。在满足客户对塑件使用要求的条件下,通过优化塑件结构,以及在塑件壁厚最厚的圆柱区域进行减胶处理,使填充过程中的流动缺陷消失,气穴分布和熔接痕显著减少,提升了注塑质量,提高了开模成效。

基于MoldFlow汽车C柱饰板三角窗变形解决方案

通过模流分析软件对汽车C柱饰板三角窗区域变形,采取分割法分别对加强筋及制件壁厚对变形影响趋势进行比较分析,快速确定了最终改模方案,经试模验证,一次性解决变形问题,借助MoldFlow翘曲变形分析有效降低了试模和改模成本。

汽车激光雷达盖板的双色注塑模具设计

根据某车型激光雷达盖板的双色结构及形状,采用动模型芯旋转式结构的模具方案,设计了一套一出二的热流道双色注塑模具。利用Moldflow软件进行了双色成型分析,双色注塑第一次注射成型透明的PMMA材料的产品,第二次注射成型黑色ASA材料的产品。为实现该双色产品的结构成型,在定模处设计了2组不同结构的型腔,在动模处设计了2组左右对称的型芯,并且,在型芯侧设计了双斜导柱抽芯机构,冷却系统设计为“直通式+隔水片”的随形循环水路;顶出系统设计为2组独立的液压油缸,在产品顶出取件中,第一次注射成型的PMMA产品不顶出,第二次注射成型的ASA材料的产品采用“直顶+斜顶”的组合机构将双色产品推出,最终通过机械手完成产品的取件。实践生产证明了该双色模具结构合理、运行稳定、成型的双色塑件表面无缺陷。

基于Moldflow的盒盖注塑成型优化分析

该文以盒盖为研究对象,分析塑件的结构和材料特性。通过运用Moldflow软件获得塑件的最佳浇口位置,在此基础上,对塑件的充填时间、流动前沿温度、体积收缩率和质量预测进行分析。仿真结果表明,塑件在成型过程中存在较大的体积收缩率,这可能引起塑件的质量缺陷,同时在质量预测中出现塑件有质量不被接受的部位,其原因在于塑件结构中壁厚相差较大。在满足塑件使用性能要求的前提下,通过优化塑件局部结构,在塑件厚度最厚部位进行减胶处理,使填充过程中的体积收缩率降低至7.674%,质量预测显示提升注塑件的质量。

工业监控器外罩收缩侧型芯注射模设计

结合工业监控器外罩塑件的注射成型,设计了一副两板式热流道模具。在模具整体结构设计的基础上,利用CAE仿真辅助分析并验证了复合式浇注系统的可行性及冷却系统的有效性。分析结果表明,成型后塑件的变形可减小至0.58 mm,能满足MT3级要求。为解决模具结构中塑件转轴套内壁环凹槽的自动脱模问题,设计了一种2次抽芯复合机构,相向收缩抽芯的2个差速滑块在有限空间内(20 mm)实现了环槽的自动脱模。为解决内壁上倒钩柱的自动脱模问题,设计了一种两瓣式弹性顶针用作该特征的脱模。当两瓣弹性顶针顶出倒钩柱时,两瓣弹性顶针由于弹性原因而张开,与倒钩柱分离,实现了该特征的自动脱模。

小型电动汽车信号器外壳注射模设计

介绍了电动汽车信号器外壳的注射模设计。塑件成型材料选用科思创PC 2456,采用两板模进行成型。浇注系统中,使用2个扇形冷浇口对模腔进行浇注。塑件注塑工艺参数选定为,喷嘴出口料温为230~250℃;注射速度为200 mm/s;模具温度为80℃;注射时间为1~5 s,注射压力为80~100 MPa;保压时间为5~10 s,保压压力为40~60 MPa;背压为2~4 MPa;冷却时间为10~15 s。模具中,针对塑件外壁、内壁的脱模困难,设置了5个斜导柱滑块机构、1个3次抽芯复合机构、1个中抽式内收先抽芯滑块机构、3个斜顶机构、6个推管机构及多根顶针用于塑件的脱模。其中,3次抽芯复合滑块机构中,3个抽芯滑块组合在一起,先通过第一次开模驱动2个滑块联动抽芯,再通过第二次开模驱动3个滑块同步抽芯和移动,较为妥善地解决了塑件侧槽需二次抽芯脱模难题。模具机构选用恰当,紧凑合理,动作达标;与其它设计方案相比,制造成本约降低减少13%,工作效率约提高5%。