基于Moldflow与正交试验法的注塑参数优化

在塑料产品的开发过程中,涉及到塑料模具进行注塑,注塑模具开发方案确定后,最重要的就是如何选择注塑参数。注塑参数可以在注塑机上直接进行试生产来调试,但必须是模具制造出来之后才能进行,对场地和设备均有要求,而且在试模过程中会浪费一定的塑料原材料。本文采用正交试验法对注塑参数进行优化,利用Moldflow软件的模具CAE技术对正交试验过程各种取值情况进行验证,并对最终优化组合进行验证,检验正交试验的正确性。确定翘曲变形量为实验指标,以注射温度、模具温度、充填时间、冷却时间、保压时间为变量的5因素,取各自允许取值范围进行4均分得到4水平,形成一个5因素4水平的正交试验矩阵设计实验,找出KDC-1型电磁断路器塑料壳体充填优化组合,通过在Moldflow的验证,及时反映了该正交试验结果是正确的注塑参数最优组合。     

Optimal design of medium channels for water-assisted rapid thermal cycle mold using multi-objective evolutionary algorithm and multi-attribute decision-making method

Rapid heat cycle molding technology developed recently is a novel polymer injection molding process. In this study, a new water-assisted rapid heat cycle molding (WRHCM) mold used for producing a large-size air-conditioning plastic panel was investigated. Aiming at improving heating efficiency and temperature distribution uniformity of the mold cavity surface, a two-stage optimization approach was proposed to determine the optimal design parameters of medium channels for the WRHCM mold. First of all, the non-dominated sorting genetic algorithm-II (NSGA-II) combined with surrogate models was employed to search the Pareto-optimal solutions. Subsequently, the Technique for Order Preference by Similarity to Ideal Solution was adopted as a multi-attribute decision-making method to determine the best compromise solution from the Pareto set. Then, the layout of the medium channels for this air-conditioning panel WRHCM mold was optimized based on the developed optimization method. It was indicated that the heating efficiency and temperature distribution uniformity on the mold cavity surface were greatly improved by using the optimal design results. Furthermore, the effectiveness of the optimization method proposed in this study was validated by an industrial application.     

Optimization of conformal cooling channels with array of baffles for plastic injection mold

Cooling system has an important role in the injection molding process in terms of not only productivity and quality, but also mold-making cost. In this paper, a conformal cooling channel with an array of baffles is proposed for obtaining uniform cooling over the entire free-form surface of molded parts. A new algorithm for calculating temperature distribution through molding thickness, mold surface temperature and cooling time was presented. The relation among cooling channels’ configuration, process parameters, mold material, molding thickness and temperature distribution in the mold for a given polymer is expressed by a system of approximate equations. This relation was established by the design of experiment and response surface methodology based on an adequate physical-mathematical model, finite difference method and numerical simulation. By applying this approximate mathematical relation, the optimization process for obtaining target mold temperature, uniform temperature distribution and minimizing the cooling time becomes more effective. Two case studies were carried out to test and validate the proposed method. The results show that present approach improves the cooling performance and facilitates the mold design process in comparison to the trial-and-error simulation-based method.     

鼠标外壳注塑件翘曲变形模拟分析

基于CAE数值分析技术和田口实验方法,研究了保压压力、熔体温度、冷却时间、保压时间和模具温度等因素对翘曲变形的影响.以翘曲变形量最小为目标,通过正交试验方法获得了最佳参数组合以及最佳参数组合条件下的翘曲变形量.结果显示,通过模流分析来预报产品缺陷,优化工艺参数,可以缩短模具开发周期,降低成本,提高企业竞争力.     

注塑模具瞬态温度仿真研究

以变径管注塑模具为例,采用ANSYS软件进行瞬态热分析,对模具和塑件的冷却过程进行仿真。该方法能够直观显示模具和塑件在各个时刻的瞬态温度分布,可检验冷却效果,为保压周期的的确定和模具优化设计打下基础。     

Design of U-shape milled groove conformal cooling channels for plastic injection mold

Besides the solid free-form fabrication technology, milling operation is an alternative applicable method to make complex cooling channels conform to the surface of the mold cavity. This paper presents the U-shape milled groove conformal cooling channels and proposes the design optimization process in order to obtain an optimal cooling channels’ configuration and target mold temperature. The relation between the cycle averaged thermal behavior of the mold cavity and the two-dimensional configuration of cooling channels was first investigated thoroughly by an analytical method. Design of experiment and 2D simulation were done to obtain the mold wall temperature and to check the feasibility of the analytical method. The optimization process of the free-form conformal cooling channels is based on the combination of both analytical method and 3D CAE simulation. The analytical step relies on explicit mathematic formulas, so it can approach the neighboring optimal solution quickly. Subsequently, the three-dimensional heat transfer simulation is applied to fine-tune the optimization results. A case study for a plastic car fender was investigated to verify the feasibility of the proposed method. The results show that conformal cooling channel gives a uniform cooling, reducing the cooling time and increasing the molded part’s quality with less effort of plastic designers and high computational efficiency.     

基于数值模拟和3D打印的热冲压模具随形水道设计制造研究*

针对传统热冲压模具深孔对钻冷却系统冷却不均的现象,基于热冲压过程的多场耦合传热理论,提出热冲压模具随形冷却系统设计方法。利用Star-ccm+软件对热冲压冷却淬火过程进行热流固耦合模拟。以自主研发的彩虹电动汽车B-柱模具镶块为研究对象,对传统深孔对钻和新提出多种随形设计方案进行了冷却模拟分析。根据模拟结果,比较分析了不同冷却方案的冷却效果,并提出B柱模具镶块纵向随形冷却水道的优化方案,分析了优化前、后模面温度场的变化。提出运用覆膜砂3D打印造型结合传统铸造工艺的方法,制造具有随形冷却水道的热冲压模具。通过对比五种方案发现,采用纵向随形设计的热冲压模具,与冷却最差的平行随形设计相比,模面最大温度降低47.4%,模面平均温度降低40.9%,模面温度均匀性提高1.8%。根据纵向随形水道设计流程,将水道形状和位置参数R、H、r作为优化参数,模面温度场作为优化目标,对纵向随形水道进行优化,结果显示,优化后模面最大温度下降了49.8%,模面平均温度下降了46.8%,模面温度标准偏差下降了67.5%,模面温度均匀性提高了1.9%。因此,采用随形冷却的热冲压模具,有效地提高了生产加工效率和使用寿命,改善了热冲压件的平均强度和组织与力学性能的均匀性。     

Verification and evaluation of automatically designed cooling channels for block-laminated molds

This study discusses an automatic design method of injection mold cooling channels using a genetic algorithms (GA) and a finite element method (FEM), combined with an evaluation function based on unsteady-state heat transfer and linear static deformation. The uniformity of cooling and the deformation effect were observed in the injection mold with the automatically designed cooling channel through a verification experiment. The genetic algorithm was applied in the following steps: the generation of finite elements of individuals expressing different cooling channel shapes, the definition of the fitness function to evaluate individuals, the genetic operation for individuals, and the automatic generation of the cooling channel shape. Finally, based on a molding experiment, the cooling and deformation effects were investigated. Results of resin cooling uniformity, temperature distribution of molding parts, and deformation of mold were demonstrated.     

离心熔铸非球面镜镜胚面形偏差工艺参数的敏感性研究

离心熔铸技术在大口径非球面镜镜胚的制造方面具有独特优势。本文通过自行研制的缩比模型实验机进行试验,深入研究了离心熔铸工艺及成型镜胚质量,详细介绍了模具涂层的制备、离心熔铸的加热及冷却等工艺过程,制备了非球面镜镜胚模型。采用数值模拟与试验研究相结合的方法,对所得镜胚面形偏差工艺参数的敏感性进行了研究。分析了模具的热膨胀系数、镜胚冷却速率、直径及加热温度对面形偏差的影响,得到了偏差工艺参数的敏感性规律。通过对面形偏差进行两次迭代补偿,面形偏差值从-84μm降到33μm,补偿后的结果满足设计要求。采用离心熔铸技术,可以制备满足上表面垂直偏差在30~40μm范围内的非球面镜镜胚。     

Process parameters optimization of injection molding using a fast strip analysis as a surrogate model

Injection molding process parameters such as injection temperature, mold temperature, and injection time have direct influence on the quality and cost of products. However, the optimization of these parameters is a complex and difficult task. In this paper, a novel surrogate-based evolutionary algorithm for process parameters optimization is proposed. Considering that most injection molded parts have a sheet like geometry, a fast strip analysis model is adopted as a surrogate model to approximate the time-consuming computer simulation software for predicating the filling characteristics of injection molding, in which the original part is represented by a rectangular strip, and a finite difference method is adopted to solve one dimensional flow in the strip. Having established the surrogate model, a particle swarm optimization algorithm is employed to find out the optimum process parameters over a space of all feasible process parameters. Case studies show that the proposed optimization algorithm can optimize the process parameters effectively.     

Determining the effects of thermal conductivity on epoxy molds using profiled cooling channels with metal inserts

Polymer injection molds are generally manufactured with metallic materials, such as tool steel, which provide reliable working of molds and extended service life. The manufacture of injection molds with steel is a prolonged process because of the strength of steel. For a short prototype production run, one of the suitable choices could be the use of aluminum-filled epoxy material, which can produce a functional mold in a short time as compared with a conventionally machined tool. Aluminum-filled epoxy tooling is a good choice for short production runs for engineering applications, yet works best for relatively simple shapes. The advantages in relation to the fabrication of injection molds with epoxy-based materials include time saving in producing the mold, epoxy curing at ambient temperature, and ease of machining and post processing. Nevertheless, one major drawback of epoxy material is its poor thermal conductivity, which results in a relatively longer cooling time for epoxy injection molds. This study investigates some of the innovative ideas for enhancing the thermal conductivity for epoxy molds. The basic concept behind these ideas was to embed a highly thermally conductive metal insert within the mold between cavities with an innovative design of cooling channels called profiled cooling channels. This technique will increase the effective thermal conductivity of the epoxy mold, leading to the reduction in cooling time for the injection molded polymer part. Experimental analysis conducted in the current study also verified that the mold with profiled cooling channels and embedded metal insert has significantly reduced the cooling time.     

ADC12铝合金压铸件冷却机理研究

铝合金压铸件从压铸模取出后,在不同的冷却水温下,对铸件的冷却效果及残热现象进行研究,寻求最佳的冷却水温,使铸件温度控制在最优范围内,以获得最佳质量.     

注射模具调温系统设计

模具温度(模温)指模具型腔和型芯的表面温度。不论是热塑性塑料还是热固性塑料成型,模具温度对塑料熔体的充模流动、固化定型、生产率及塑件的形状和尺寸精度都有重要的影响。主要介绍一防护罩制件注射模具调温系统设计方法,通过有效的对模具温度进行调节,对模具进行冷却或加热,必要时两者兼有,从而达到控制模温的目的。     

Optimum process conditions on shrinkage of an injected-molded part of DVD-ROM cover using Taguchi robust method

Plastic injection molding is an important process to produce thin-shell parts. However, the difficulty in adjusting optimum process conditions may cause defects of the injected-molded parts such as shrinkage. This study investigates on the optimum combinations of process conditions on shrinkage of an injected-molded part of the DVD-ROM cover based on Taguchi method. In doing this, a series of Moldflow analyses have been performed as per L₂₇ orthogonal array design with each analysis by means of the process conditions of mold temperature, melt temperature, injection pressure, injection time, and cooling time. In the meantime, signal-to-noise (S/N) ratio is utilized to determine the optimum combinations of the process conditions for shrinkage through analysis of variance (ANOVA). ANOVA is further used to find which of the process conditions are statistically significant. Finally, confirmation tests at the optimum combinations of the process conditions were executed to verify the robustness and the effectiveness of Taguchi method within 95% confidence interval. From the findings, it can be stated that Taguchi method is a powerful tool for evaluating the defect of shrinkage in the plastic injection molding.     

基于神经网络和遗传算法的薄壳件注塑成型工艺参数优化

建立基于神经网络和遗传算法并结合正交试验的薄壳件注塑成型工艺参数优化系统.正交试验法用来设计神经网络的训练样本,人工神经网络有效创建翘曲预测模型;遗传算法完成对影响薄壳塑件翘曲变形的工艺参数(模具温度、注射温度、注射压力、保压时间、保压压力和冷却时间等)的优化,并计算出其优化值.按该参数进行试验,效果良好,可以有效地减小薄壳塑件翘曲变形,其试验数值与计算数值基本相符,说明所提出的方法是可行的.     

Cooling a slab continuous-casting mold

The results of calculation of cooling the walls of a slab continuous-casting mold, effected by way of heat pipes, for steel casting are presented. The novelty is confirmed by a patent for a method of cooling the mold during casting a high-temperature metal and by a device for its implementation. At a given heat-flux density in the wide wall from the steel casting, the temperatures of the operating surface of the mold wall, coolant vapor flow rate and its temperature, and the cooling medium flow rate are determined.     

基于虚拟正交试验的发动机冷却风扇设计参数优化

汽车冷却风扇的设计参数决定其工作性能,进而对整车散热性能有直接影响。采用计算流体力学的方法,分析风扇轴向伸入距离、风扇与风扇罩径向间隙和风扇旋转中心偏移距离三种不同参数对散热器进风量和风扇有效功率的影响规律。在此基础上,通过虚拟正交试验的多目标耦合分析,得到风扇设计参数的优化方案。并通过数值仿真与整车热平衡试验对优化方案进行验证。结果显示,优化后车型在模拟爬坡工况下,散热器,冷凝器进风量和风扇有效功率分别提升10.89%、4.08%和12.78%,发动机表面温度降低0.91℃,发动机舱散热性能显著提升,内部温度分布状况明显改善。     

基于UG的内螺纹瓶盖注塑模设计

UG MoldWizard是UG系统的一个独立的智能化设计注射模具的模块,它运用知识嵌入的基本理念,按照注射模具设计过程的一般顺序来实现模具设计的整个过程.在本次内螺纹瓶盖的设计中,充分体现UG在注塑模设计中的高效和快捷.通过对内螺纹瓶盖工艺分析,巧妙地采用镶块成型内螺纹和项出塑件,从而简化模具结构.并对模架、浇注系统...     

汽车仪表板注塑模具的CAE优化分析与设计

采用计算机三维造型得到汽车仪表板的实体模型,利用MoldFlow软件对模型进行了有限元分析,完成了浇注系统、冷却系统及成形工艺的设定。在对熔体充模、保压、冷却进行模拟的过程中,实现了对模具结构的CAE优化。计算机三维造型与CAE优化的结合运用,能对熔体充模过程及模具开合模动作进行仿真,可直观地获得产品及模具的可视化信息,防止设计不足而可能造成的模具返修,降低了产品创新开发的成本,有效地缩短了汽车仪表板注塑模具的研制周期,提高了模具应用的可行性,因而保证了产品质量,使生产效率得到提高。     

注塑模温度场测量技术的研究

为改进设计注塑模冷却系统提供依据,研制了注塑模温度场微机自动测量系统,该系统能够对注塑模各层面温度场进行测量,该系统采用多点快速采集板,直接与微机联机便能开始工作,该系统在工程允许的误差范围,由于其测量方法构思巧妙、测量系统通用性强,性能价格比高、是目前注塑温度场温度理想的测量系统.