调味盒注塑模具设计

通过对调味盒结构的工艺分析,对该塑件模具的设计要点作了介绍,并对模架、冷却系统、成型零件、浇注系统和推出机构等模具的主要组成部分进行了重点分析。实践证明该模具结构合理、动作可靠、塑件质量符合设计要求。     

基于MPI的电器开关盒上盖注塑成型分析

以电器开关盒上盖为实例,应用MPI软件对其注塑过程中的填充、冷却、翘曲进行模拟。分析了填充时间、熔接痕等情况,得到合理的浇口位置;通过研究翘曲的影响因素,提出了改进翘曲的方案,最终减小了翘曲变形。     

Determination of the transition temperature at different cooling rates and its influence on prediction of shrinkage and warpage in injection molding simulation

In injection molding simulation the phase change from melt to solid state is usually simplified by using a so called transition temperature. In the present work, the transition temperatures of several amorphous and semicrystalline polymers were determined using DSC‐runs at different cooling rates. The transition temperature was described as a function of cooling rate. The obtained transition temperatures of the semicrystalline polymers were used in injection molding simulations with the commercial software package Autodesk Moldflow Insight 2010 to calculate the shrinkage and warpage of box‐shaped test parts. The simulation results were compared with the experimental values of optically measured injection‐molded boxes. The results showed a strong influence of the transition temperatures on the simulation results of a 3D model and a very low influence for a 2.5D model. Transition temperatures obtained at higher cooling rates improved the 3D simulation results for several dimensions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

基于MPI的汽车内置储物盒注塑模具优化设计

以某汽车内置储物盒为研究对象,结合聚合物流变学的基本理论,采用Moldflow软件对汽车内置储物盒注射成型进行模流分析。针对储物盒制件在注射过程中出现的表面缩痕严重、达到顶出温度的时间长和翘曲量大等诸多缺陷,将实体模型的浇注系统和冷却系统等进行重新设计。通过对各个质量评价指标进一步分析发现,优化后储物盒制件的各种缺陷消除或减小,缩痕指数由0.638 2~4.009降低为零、零件达到顶出温度的时间由37.92~92.68 s降低到19.87~21.40 s、总翘曲量由1.166~1.782 mm降低到0.024 0~0.416 5 mm,优化效果明显。在此基础上进行汽车内置储物盒注塑模具的设计,并试模加工出了合格的制件。     

钢化玻璃冷却系统中集风箱结构的分析与探索

介绍玻璃物理钢化冷却结构的集风箱,通过对集风箱结构的分析、改进与理解,分析该结构对钢化玻璃质量的影响因素。     

注塑成型工艺参数对PP饭盒盖翘曲变形量的影响研究

以聚丙烯(PP)饭盒盖为研究对象,针对其在注塑过程中存在的质量缺陷问题,以翘曲变形量为优化目标,熔体温度、模具温度、保压时间、冷却时间为影响因子设计了4因素5水平的正交试验。用Moldflow软件进行仿真,对试验结果采用极差分析法,获得了使翘曲变形量最小的各因素水平,进而获得最佳工艺参数组合。其中熔体温度为275℃,模具温度为80℃,保压时间为12 s,冷却时间为45 s,优化后翘曲变形量为1. 699 mm。最佳工艺参数组合有效降低了翘曲变形量,并且发现各因素对塑件质量的影响程度为熔体温度>冷却时间>保压时间>模具温度,为实际生产提供了理论指导。     

Tailoring the crystalline morphologies and mechanical properties of high‐density polyethylene parts by a change in the fluid flow pattern under gas‐assisted injection molding

In this study, an increase in the cooling rate of high‐density polyethylene parts was carried out via a change in the fluid flow pattern to introduce gas cooling under a gas‐assisted injection‐molding process; this was conducive to the retention of orientation chains shaped during the injection stage and further developed into much more oriented crystals. Morphological observation showed that the parts without gas cooling (WOGC) were composed of oriented crystals except the gas channel zone, whereas the parts with gas cooling (WGC) were full of oriented crystals, especially much more interlocking shish‐kebab structures in the subskin zone. The WGC parts had a higher degree of orientation than the corresponding zone of the WOGC parts. Although the lower crystallinity, the wider orientation regions, and much more interlocking shish‐kebab structures led to considerable increases from 32 and 990 MPa in the WOGC parts to 36 and 1150 MPa in the WGC parts for the yield strength and elastic modulus, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40349.     

Experimental investigation and numerical simulation of cooling process in water assisted injection moulded parts

Abstract

This report investigated, both experimentally and numerically, the cooling process in water assisted injection moulded parts. Experiments were carried out on a laboratory developed water assisted injection moulding system, which included an injection moulding machine, a water pump, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The resin used was semi-crystalline polypropylene. The in-mould temperature of the polymeric materials during the cooling process was measured. A transient heat transfer finite element model was adopted to simulate and predict the temperature variation within water assisted injection moulded products. Simulated results matched well with the experimental data. Experimental investigation and numerical simulations of a water assisted injection moulding cooling process can provide an improved understanding of the influence of water related parameters on the cooling process of water assisted injection moulded parts.     

Extension of the orientation region of high density polyethylene molded by gas‐assisted injection molding: control of the thermal field

Wider zones with close‐knit orientation crystals in high density polyethylene (HDPE) parts prepared via the gas‐assisted injection molding (GAIM) process were obtained under high cooling gas pressure. In this study, compressed nitrogen, as a cooling medium, was introduced to retain a high cooling rate of the polymer melt. The high gas pressure leads to fast cooling of the polymer melt, which contributes to the stability of more oriented and stretched chains during the cooling stage. Then many more oriented structures are formed. SEM shows that many more oriented structures and interlocking shish‐kebab structures are achieved in parts under highest cooling gas pressure (P3). The P3 parts possess a higher degree of orientation than the corresponding regions of parts under lowest cooling gas pressure (P1). Moreover, tensile testing indicates that, compared with P1 parts, although P3 parts have lower crystallinity, the mechanical properties are improved because of the wider orientation zone and many more interlocking shish‐kebab structures. Combining the HDPE molecular parameters with the characteristics of the GAIM flow field and temperature field, the stability of oriented or stretched chains and the formation of orientation structures in various zones of the parts were analyzed. © 2014 Society of Chemical Industry     

冷却塔落水降噪装置的试验研究

冷却塔的噪声污染正成为当今亟待解决的问题。本文对新开发的冷却塔落水消能降噪装置在模拟自然通风冷却塔的条件下的降噪效果进行了研究,结果表明,采用该降噪装置,在淋水密度为4～16t/(m2·h)的范围内,冷却塔的噪声可降低15dB以上,降噪装置主要是削减了声源中的高频成分。     

基于GRNN-NSGA的带嵌件注塑件多目标优化

带嵌件的注塑产品成型过程相较于传统注塑产品较为复杂,产品成型周期和产品质量难以预测。针对这一问题,以带嵌件的静电检测盒为例,运用广义神经网络(GRNN)和非支配排序遗传算法(NSGA-Ⅱ),对注塑成型过程进行控制与优化。以熔体温度、模具温度、注射时间、冷却时间、保压压力和保压时间为输入层,体积收缩率、X方向翘曲变形、Z方向翘曲变形作为输出层,建立GRNN模型。利用正交试验设计得到的样本对神经网络模型进行训练和测试,运用NSGA-Ⅱ对建立的模型进行优化,最终三个目标值分别降低了30.96%、22.76%、15.62%,表明该方法可以对注塑成型过程进行预测和控制。     

汽车接插件随形水路设计及工艺优化

根据汽车接插件的模具规格和使用要求,基于Moldflow软件对汽车接插件的成型过程进行数值模拟,设计冷却系统和流道系统,针对冷却系统对热流道区域冷却不足的问题进行优化,增加随形水路。根据Taguchi正交实验分析了熔体温度、模具温度、注塑时间、保压时间、保压压力5个因素对产品框口区域翘曲变形的影响规律,得到最佳工艺参数组合,最后对最佳参数组合进行了模拟验证。实际生产表明,该方案可以缩短产品的开发周期与成型周期,提高生产效率。     

Mathematical Model of the Dissolution Stage in Cooling Batch Crystallization

Abstract

Experiments were performed in a cooling batch crystallizer to develop a phenomenological model that represents the dissolution stage in crystallization. Two models were used: a theoretical and a black box, comparing their results with the experimental ones through the simulation of these models (use the mean and the standard deviation of crystal size like comparative means). The theoretical model was obtained by population's balance, mass and energy balances, and constitutive relations (decrease speed and production‐reduction speed). The black box model consisted of a set of equations, which are functions of the mean, standard deviation, agitation speed and time.     

狭长型薄壁零件的注塑模3D打印随形水路设计及开发

针对狭长型薄壁零件的注塑模具冷却优化问题,以典型零件引水管为研究对象,采用随形水路的冷却设计方案,通过Moldflow软件,进行随形水路与传统水路的仿真模拟及对比.结果 表明,随形冷却在产品表面温度分布均匀性上提升了52.6％,冷却时间上缩短了19.7％,整个注射过程填充情况良好,体积收缩符合要求;并采用选择性激光熔化...     

Establishing a rapid cooling complex mold design for the quality improvement of microcellular injection molding

Injection molding is one of the most widely-used processes for the production of plastic parts, due to the utilization of diverse materials, the complex product-shape moldability, and the rapid mass production. In relation to the environmental issues, light-weight technology and green molding solutions are becoming more important. Microcellular injection molding technology is one of the green molding solutions for saving materials, as well as reducing the weight of molded parts. However, the molding process brings about some defects, including a sliver flow mark on the surface and uneven mechanical properties that are caused by the uneven cell size and their distribution within the part. Dynamic molding temperature control technology seems to be an effective way of improving the product quality. Until recently, there has been very little discussion about high-efficiency cooling methods. A new complex mold for a cooling system has been designed. The basis cooling ability of different materials was investigated. The complex mold design has a faster cooling rate, and it has a greater surface temperature uniformity. This cooling technology was used to improve the quality of microcellular injection molded parts, which improves the glossy finish by about 73%. The results show that the faster cooling rate brings about the more uniform cell size with higher cell density from 9.43E+11 to 1.92E+12 cells/cm³. Otherwise, the cell size reduced from 192.92 to 84.97 μm.     

盒状注塑件翘曲冷却分析及优化设计

应用Moldflow软件中MPI模块对折页盒进行翘曲冷却分析,主要分析回路冷却介质温度、冷却管道表面温度、制品最高温度位置、翘曲变形量等.结果表明,造成折页盒翘曲变形较大的主要原因是收缩不均匀.结合成型要求及成型质量对成型工艺参数进行了调整,并对冷却水道进行了改进设计.     

我国海水利用工程取水构筑物型式研究

为了明晰不同海水利用工程中经济适用的海水取水构筑物型式,简化海水取水构筑物的选型过程,分类统计了现有海水冷却工程和海水淡化工程的取水流量及所采用的取水构筑物型式,并对取水流量、取水水温、水面波动和水文地质对取水构筑物选型的影响进行了分析.结果 表明,取水流量是决定海水取水构筑物选型的最重要因素.在取水流量范围依次减小的...     

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。     

Formation mechanism of crystal morphologies in LLDPE/HDPE blends investigated via water‐assisted and conventional injection molding

The LLDPE/HDPE blends with two different weight ratios as well as pure LLDPE were molded by means of water‐assisted and conventional injection molding (WAIM and CIM) in terms of their different thermal fields. The formation of the crystal morphology in the molded parts was investigated by a scanning electron microscope. The results showed that banded spherulites formed in the WAIM and CIM pure LLDPE parts. Banded spherulites of LLDPE coexisted with the randomly oriented lamellae of HDPE for LLDPE/HDPE blend parts with lower HDPE content at higher cooling rates, whereas a banding to nonbanding morphological transition occurred for LLDPE component (particularly for blend with higher HDPE content) at lower cooling rates. The heterogeneous nucleation effect of HDPE component on LLDPE component was responsible for the banding to nonbanding morphological transition by hindering the twist of LLDPE lamellae. It was interesting to find that the thermal effect, rather than the shear effect, was the main factor for the formation of crystal morphologies in both CIM and WAIM blend parts. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

中海化学二期冷箱及膨胀机试车和运行情况分析

介绍中海化学二期装置原始开车以来,冷箱、膨胀机试车及运转情况,以及存在的一些问题,针对这些问题系统所作的一些调整及改造措施。