基于模具补偿法的机械式胀形桥壳回弹控制

目的解决由回弹引起的机械式胀形桥壳形状尺寸不精确的问题。方法采用Marc软件平台和物理实验相结合的方法展开研究,运用补偿法对模具进行修正,补偿回弹量。结果机械式胀形过程中,桥壳回弹量较大,单侧回弹量达到6.06 mm,严重影响其形状尺寸精度。结论通过对模具进行适当修正,桥壳回弹量得到了很好补偿,成形效果较好,得到了符合要求的桥壳零件,进一步完善了该工艺的理论基础。     

基于混沌粒子群的微齿轮注塑精密成形翘曲变形分析

目的 针对注塑加工生产的微齿轮运转一段时间后会出现严重变形的问题,对微齿轮注塑精密成形翘曲变形进行分析。方法 基于混沌粒子群建立微齿轮注塑CAE模型,获取曲面全局最优解,在此基础上,计算微齿轮注塑精密成形翘曲收缩率,得到翘曲变形量,同时优化微齿轮注塑精密成形工艺参数,分析微齿轮注塑精密成形翘曲变形情况。结果 将仿真结果与实际试验结果进行对比,得出该分析方法的预测结果与实际翘曲变化趋势完全一致。结论 微齿轮注塑中心位置的翘曲变形量最大,离中心位置越远,翘曲变形量越小。     

长条形塑料制品翘曲变形研究

文章对长条形薄壁塑件翘曲变形机理进行了分析，找到了产生翘曲变形的原因及影响规律，提出了解决的方法，论述了在设计模具时应采取的预防措施。     

基于DOE和RSM的轴流风扇叶片成型精度分析与优化

轴流风扇通常采用注塑工艺制造,其翘曲变形缺陷影响精度,导致风扇的叶珊结构变化,进而影响动力、噪声、动平衡等方面性能。以一种平直翼型轴流风扇为研究目标,采用聚对苯二甲酸丁二醇酯(PBT)材料为注塑原料,对扇叶的注塑成型过程进行模拟仿真,利用田口实验(DOE)分析工艺参数对翘曲变形的影响,确定了各工艺参数对扇叶结构的影响权重,得出模具表面温度、熔体温度、注射时间、保压压力为主要影响因素;另外,采用响应曲面法(RSM)实验设计确定最佳工艺组合,将最大Z方向翘曲量从0.197 0 mm降低到0.108 1 mm,平均Z方向翘曲量从0.104 0 mm降低到0.035 9 mm,分别优化了0.088 9 mm和0.068 1 mm。     

短玻纤增强聚丙烯复合材料气体辅助注塑成型真三维模拟

基于广义非牛顿流体和七参数Cross-WLF黏度本构,以矩形平板塑件为研究对象,选用短玻璃纤维增强聚丙烯复合材料,采用Moldflow软件对传统注塑成型和气体辅助注塑成型过程进行真三维模拟,对比研究了两种成型工艺中注射压力、锁模力和塑件变形情况,结果表明,采用气辅注塑成型能有效降低注射压力和锁模力;采用气辅注塑成型能减小塑件的变形,在文中工艺条件下,传统注塑成型塑件的变形量为1.187 mm,而气辅注塑成型塑件的变形量为0.7839mm,变形缩小了51.4%,尤其是采用气辅注塑成型能明显减小塑件的收缩变形量,其收缩变形量从1.042 mm降低至0.6839 mm。     

汽车饰盖CAE分析及成型工艺优化

针对汽车饰盖塑件不仅外观要求高,而且内置众多细小筋板等复杂结构导致缩痕、翘曲变形等注塑缺陷难以控制,造成产品模具结构与成型工艺设计困难,提出了一套含复杂筋板注塑件的成型工艺参数优化方法。基于CAD/CAE技术,通过模拟分析筋板壁厚对成型质量的影响,获知筋板厚度对产品翘曲变形量影响显著,但并不呈正相关,较大的筋板厚度导致产品缩痕明显,当筋板厚度为1mm时产品缩痕达到最小值(0.02mm)。运用综合平衡法对成型参数进行优化,使产品最大翘曲变形量下降约25%,再利用斐波那契法进行分段保压优化,通过8次迭代演算后符合收敛条件,获取了理想的保压参数,最大变形量继续下降约37%,最终产品翘曲变形量满足技术要求。生产实践证明该方法简单实用,不仅解决了筋板成型缩痕及翘曲变形难以控制的问题,而且缩短了产品研发周期和节约了成本,为类似产品成型设计提供参考。     

航空发动机燃烧室帽罩变压边热成形技术

目的 提出帽罩零件真空环境变压边热成形新技术,解决航空发动机燃烧室帽罩零件冷成形回弹大、精度低、内部应力大,以及热成形壁厚不均、氧化严重等问题。方法 利用有限元仿真和工艺试验相结合的方法,选用GH3625高温合金板材研究变压边热成形过程中压边力加载路径对帽罩成形质量的影响,分析热成形模具热膨胀与回弹变形对帽罩尺寸精度的影响,建立考虑热成形、变压边力加载及模具补偿的成形方案。结果 在900 ℃条件下,帽罩热成形力相比室温下降低约70%,内外径回弹量分别降低约67%和59%。基于几何特征优化的压边力加载路径有助于减小零件型面的回弹。结合回弹变形和热膨胀变形补偿,确定模具总补偿量为内径?0.49 mm,外径?0.62 mm。工艺试验结果表明,采用模拟所确立的成形方案成形的帽罩质量较好,尺寸精度达到IT9级,型面精度在0.2 mm以内,切边后回弹量为0.1 mm,与有限元仿真结果吻合较好。结论 建立的有限元模型和变形补偿方案可以有效地优化帽罩的工艺成形过程,所提出的变压边热成形技术能够显著降低高温合金变形抗力和回弹,可以解决高精度帽罩零件成形制造难题。     

某汽车零件注塑模设计及成形过程CAE分析

在综合考虑某塑件成形工艺特点的基础上,确定该塑件的模具结构方案,设计注塑模具,并在理论设计基础上绘制模具装配图,分析模具工作原理,然后通过三维造型软件对模具进行实体造型,最后利用Moldflow软件对塑件进行成形性能分析。     

基于正交分解的模具参数优化

正为了对薄壁小型带内螺纹做综合研究的模具设计给出一个行之有效的思路。本文以现实工作的塑料制件之一的翻盖盖子为分析对象,对注塑模具的设计与应用技术进行了深入的研究,针对翘曲缺陷,利用正交分解法在不改变模具结构的基础上,找出最佳的工艺参数组合,降低塑料制件的翘曲等变形至最小,得到最优方案后进行生产制造。模具开发当中一般会遇到各种注塑     

聚合物微流控芯片的注射成型

针对注塑成型微流控芯片过程中出现翘曲变形和微通道复制精度不高等缺陷,采用正交分析法,仿真优化了芯片厚度方向上的翘曲变形;基于翘曲优化结果,实验研究了微注射成型微流控芯片过程中模具温度、熔体温度和注射速度对微通道变形的影响。结果表明,保压时间和保压压力对微流控芯片的翘曲变形影响最大,而模具温度对微通道变形影响最为显著。采用优化的工艺参数,所成型的芯片微通道具有较高的复制度,无明显翘曲变形,可满足使用要求。     

Back Propagation neural network modeling for warpage prediction and optimization of plastic products during injection molding

Warpage of plastic products is an important evaluation index for Plastic Injection Molding (PIM). A Back Propagation (BP) neural-network model for warpage prediction and optimization of injected plastic parts has been developed based on key process variables including mold temperature, melt temperature, packing pressure, packing time and cooling time during PIM. The approach uses a BP neural network trained by the input and output data obtained from the Finite Element (FE) simulations which are performed on Moldflow software platform. In addition, a kind of automobile glove compartment cap was utilized in this study. Trained by the results of FE simulations conducted by orthogonal experimental design method, the prediction system got a mathematical equation mapping the relationship between the process parameter values and warpage value of the plastic. It has been proved that the prediction system has the ability to predict the warpage of the plastic within an error range of 2%. Process parameters have been optimized with the help of the prediction system. Meanwhile energy consumption and production cycle were also taken into consideration. The optimized warpage value is 1.58 mm, which is shortened by 32.99% comparing to the initial warpage result 2.358 mm. And the cooling time has been decreased from 20 s to 10 s, which will greatly shorten the production cycle. The final product can satisfy with the matching requirements and fit the automobile glove compartment well.     

注塑成型有限元分析管理和成型工艺优化系统

目的针对注塑成型工艺过程,开发有限元分析项目流程管理和工艺参数优化的集成系统。方法参考企业项目流程,开发项目流程管理模块,使用多元回归拟合配合改进的模拟退火算法进行工艺参数的优化,通过塑料托盘翘曲变形量的优化来验证优化方法的准确性,进行塑料托盘的CAE分析正交试验,使用多元回归拟合试验数据并进行拟合优度检验,分别使用Isight和改进的模拟退火算法进行最优解的求解并对比计算结果,最后对得到的最优参数组合进行CAE分析得到变形量,将变形量与正交试验变形量对比。结果在回归方法中,使用惩罚系数为2的多项式岭回归效果较好,其优度指标R2为0.975,改进的模拟退火算法计算结果与Isight软件自适应模拟退火算法的计算结果基本一致,最优参数组合在Moldflow分析中的变形量为0.6805 mm,与之前的最小变形量0.7436 mm相比更小。结论使用回归拟合配合改进的模拟退火算法开发的工艺参数优化程序能起到较好的工艺参数优化效果。     

基于代理模型和改进遗传算法的注塑翘曲优化

提出一种最小化制品翘曲的注塑工艺参数优化集成方法.以空调柜机顶盖注塑制品开发为例,该方法使用Moldflow软件分析制品的翘曲变形,运用田口方法确定与制品翘曲量密切相关的工艺因素,然后采用响应曲面法(RSM)和改进的精英保留自适应遗传算法(EAGA)相结合的方法,建立主要影响工艺参数与制品翘曲量之间的关系模型,通过对模型寻优以实现对制品翘曲的优化.该方法的适用性在制品的实际生产中得到了验证.     

基于多域正交空间协同演进的薄壁注塑件翘曲优化研究

目的 鉴于细长、异形、薄壁注塑件成型机理复杂,且容易产生翘曲变形,以及传统工艺优化方法存在局限性的问题,以某轿车薄壁件为研究对象,优化注射成型工艺,以实现降低翘曲变形,提高效率的目的。方法 首先,对压力、温度因素及多重效应造成细长、异形、薄壁注塑件翘曲变形的机理进行分析。然后,在正交试验设计的基础上,应用Moldflow软件模拟仿真获取数据,并进行方差分析,获得各工艺参数的显著性。为了进一步优化工艺参数,打破传统优化方法存在的局限,提出一种多域正交空间协同演进（MDOSE）的集成优化方法。最后,基于该方法优化某轿车薄壁件的翘曲变形,并将其应用于实际生产制造。结果 与初始试验方案相比,优化后制件z方向上的翘曲从1.022 mm降低到了0.085 7 mm,减小了91.6%,证实了MDOSE优化方法的有效性和实用性。结论 优化结果表明,MDOSE优化方法一定程度上解决了薄壁件的翘曲优化问题,改善了传统工艺优化方法的局限。机理分析和工艺方法为往后的薄壁注塑件的实际生产提供了一定的理论支撑。     

Experimental study of warpage and shrinkage in injection molding of HDPE/rPET/wood composites with multiobjective optimization

In this paper, injection molding of squared parts with 1.25 mm in thickness, composed of wood plastic composites (high-density polyethylene, recycled polyethylene terephthalate, and wood flour), was done. The warpage and volumetric shrinkage in the parts was determined experimentally with various process conditions (packing time, melt temperature, wood content, and packing pressure). The experiments were done based on Box–Behnken design of experiments. The significance of each parameter and model was evaluated by analysis of variance (ANOVA). ANOVA showed that packing time and melt temperature are the most significant parameters on warpage and wood content is the most significant on volumetric shrinkage. Packing pressure and wood content had no considerable effect on warpage and packing time on shrinkage too. To obtain optimal process conditions for minimum warpage and shrinkage, a multiobjective optimization based on Pareto front was developed. Response surface method was used to find the relationships between input parameters and objective functions, and genetic algorithm presented the Pareto front solutions to determine the optimum solution. It was observed that there was a good agreement between the predicted optimum values and the experiments.     

Research on the reduction of sink mark and warpage of the molded part in rapid heat cycle molding process

Rapid heat cycle molding (RHCM) is a recently developed innovative injection molding technology to enhance the surface quality of the plastic parts without extending the molding cycle. Most of the common defects that occur in the plastic parts produced by conventional injection molding (CIM), such as flow mark, silver mark, jetting mark, weld mark, exposed fibers, short shot, etc., can be well solved by RHCM. However, RHCM is not a nostrum for all the defects in injection molding. Sink mark and warpage are two major defects occurring in RHCM. The purpose of this study is to investigate and further solve the sink mark and warpage of the molded parts in RHCM. To solve the problem of sink mark, a new “bench form” structure for the screw stud on the product coupling with a lifter structure for the injection mold was proposed. The external gas assisted packing was also proposed to reduce the sink mark in RHCM. To solve the problem of warpage, design of experiments via Taguchi methods were performed to systematically investigate the effect of processing parameters including melt temperature, injection time, packing pressure, packing time and also cooling time on the warpage. Injection molding simulations based on Moldflow were conducted to acquire the warpages of the plastic parts produced under different processing conditions. A signal to noise analysis was conducted to analyze the effect of the factors, and the optimal processing parameters were also found out. ANOVA was also conducted to quantitatively analyze the percentage contributions of the processing parameters on the warpage. The verification results show that part warpage can be reduced effectively based on the optimal design results.     

FDM技术中加热底板样式对翘曲变形的影响研究

针对熔融沉积成型（fused deposition modeling,FDM）过程中存在的典型缺陷--翘曲变形,以加热底板样式为研究重点,对比ANSYS数值模拟结果与成型实验数据,探究普通加热底板与九宫格加热底板对成型件翘曲变形量的影响。在数值模拟过程中,采用生死单元技术建立2种加热底板上成型件温度场模型,再采用热-力间接耦合的方法分析成型件的应力分布,最后得到成型件翘曲变形的位移云图,分析2种加热底板上成型件的翘曲变形量。在进行成型实验时,分别在普通加热底板与九宫格加热底板上打印试件,再进行2种加热底板成型件的4个角点的翘曲变形量的测量。对比2种加热底板上成型件在ANSYS数值模拟与成型实验中的最大翘曲变形量,结果表明：九宫格加热底板相比普通加热底板能更好地减小由成型件残余应力导致的翘曲变形,即在实际打印成型过程中,不需要对3D打印机的生产参数作任何调整,只需要将工作平台处的普通加热底板换为九宫格加热底板则能极大地减小成型件的翘曲变形,有助于得到具有较高质量精度的成型产品,这对提高成型产品质量具有重要的参考意义。     

Optimization of injection molding process parameters using sequential simplex algorithm

In this study warpage and shrinkage as defects in injection molding of plastic parts have been undertaken. MoldFlow software package has been used to simulate the molding experiments numerically. Plastic part used is an automotive ventiduct grid. The process optimization to minimize the above defects is carried out by sequential simplex method. Process design parameters are mold temperature, melt temperature, pressure switch-over, pack/holding pressure, packing time, and coolant inlet temperature. The output parameters aside from warpage and shrinkage consist of part weight, residual stresses, cycle time, and maximum bulk temperature. Results are correlated and interpreted with recommendations to be considered in such processes.     

A hybrid of mode-pursuing sampling method and genetic algorithm for minimization of injection molding warpage

This paper presents a hybrid optimization method for minimizing the warpage of injection molded plastic parts. This proposed method combines a mode-pursuing sampling (MPS) method with a conventional global optimization algorithm, i.e. genetic algorithm, to search for the optimal injection molding process parameters. During optimization, Kriging surrogate modeling strategy is also exploited to substitute the computationally intensive Computer-Aided Engineering (CAE) simulation of injection molding process. With the application of genetic algorithm, the “likelihood-global optimums” are identified; and the MPS method generates and chooses new sample points in the neighborhood of the current “likelihood-global optimums”. By integrating the two algorithms, a new sampling guidance function is proposed, which can divert the search process towards the relatively unexplored region resulting in less likelihood of being trapped at the local minima. A case study of a food tray plastic part is presented, with the injection time, mold temperature, melt temperature and packing pressure selected as the design variables. This case study demonstrates that the proposed optimization method can effectively reduce the warpage in a computationally efficient manner.     

Analysis of thermal cycling efficiency and optimal design of heating/cooling systems for rapid heat cycle injection molding process

Rapid heat cycle molding (RHCM) is a molding process that the mold cavity is rapidly heated to a high temperature before plastic melt injection, and then cooled quickly once the cavity is completely filled. Heating/cooling efficiency and temperature uniformity of the RHCM system are two key technical parameters to ensure a high productivity and high-quality products. In this study, a numerical model to analyze the heat transfer in heating and cooling phases of RHCM was built. The effect of heating/cooling medium, layout and structure of the heating/cooling channels, mold structure, etc., on heating/cooling efficiency and temperature uniformity was studied and discussed by analyzing the thermal responses of the molding system in RHCM process. Based on the simulation results, the optimization design of the RHCM mold with hot-fluid heating was performed. Then, a new RHCM mold structure with a floating mold cavity was proposed to improve the heating/cooling efficiency and temperature uniformity. The effectiveness of this new mold structure was also verified by numerical experiments. At last, a RHCM production line with steam heating and water cooling was constructed for a thin-wall plastic part. In testing production, the molding systems can be heated and cooled rapidly with a molding cycle time of about 72 s. The production results show that the aesthetics of the molded parts was greatly enhanced and the weld mark on the plastic part’s surface was completely eliminated.