塑料注塑成型浇口位置优化

塑料注塑成型可以制作大量具有高精度和复杂型腔形状的制件,其中注塑模浇口位置的设定决定了聚合物流动方向和流动平衡性,产品质量可以通过浇口位置的优化得到显著提高.通过对导致制品翘曲和影响材料性能的主要因素进行定量分析构造了浇口位置优化问题,结合遗传算法和数值模拟技术对优化问题求解,得到最优浇口位置设计.算例证明该方法不仅适用于单浇口位置优化,也适用于多浇口位置优化.     

Injection Molding Warpage Optimization Based on a Mode-Pursuing Sampling Method

This paper presents a new optimization approach for minimizing the warpage defect of injection-molded plastic parts. Existing methods in warpage optimization are either computationally expensive or, when inexpensive surrogate models are employed with fixed set of sample points, the accuracy of the surrogate model will only be ensured by a large number of sample points, which in turn will increase the amount of required computation. To address this problem, this paper applies a mode-pursuing sampling (MPS) method for warpage optimization, by integrating injection molding simulation with MPS, and by proposing a reinforced convergence criterion for the optimization process, in an attempt to search for the optimal process parameters of injection molding for minimizing warpage defect both effectively and efficiently. The MPS method can systematically generate more sample points in the neighborhood of the current optimal solution while statistically covering the entire search space. A case study of a scanner frame, where injection time, melt temperature and mold temperature are selected as the design variables, demonstrates that the proposed optimization method can effectively decrease the warpage deflection of an injection-molded part with significantly less computation required. Based on the optimization results, the paper also studied the influences of different process parameters on the severity of the warpage defect, providing a guideline for the setting of the proper process parameters.     

OPTIMIZATION OF PROCESS CONDITIONS IN GAS-ASSISTED INJECTION MOLDING

Gas-assisted injection molding has been widely used to provide promising solutions to problems in conventional molding. With additional process parameters introduced, optimization in gas-assisted injection molding is much more complex than in conventional injection molding. This paper proposes an automated design methodology for gas-assisted injection molding with robustness in consideration. By introducing a definition of gas penetration cost, the optimization problems dealing with multiple quality issues can be modeled as constrained optimization problems, with the gas penetration cost as main objective function and other quality quantities as constraints. A direct search-based optimization procedure, the Complex method, is used to optimize a bounded single-criterion problem. To illustrate the proposed methodology, a case study is carried out on simulation results.     

Optimization of injection molding design. Part I: Gate location optimization

The placement of a gate in an injection mold is one of the most important variables of the total mold design. The quality of the molded part is greatly affected by the gate location, because it influences the manner in which the plastic flows into the mold cavity. Some defects, such as weldline and overpack, can be effectively controlled only by the gate location. Therefore, the product quality can be greatly improved by determining the optimum gate location. In this paper, we develop a general methodology for gate location optimization. We first quantify quality in terms of flow simulation outputs. We can thus assess detrimental effects such as warpage and dimensional instability as a function of the independent variable, which is in this case the gate location. Next we develop methods to search for the optimum gate location. The search method introduced in this paper is a method that combines a deterministic hill climbing search with a stochastic annealing search method. The method is appropriately called simulated annealing and hill climbing (SANHIL). The criteria used for evaluation during the search process are a function of the flow simulation outputs. We demonstrate the success of the method for a complex industrial mold. The approach is applicable to any complex mold geometry and any plastic.     

A fuzzy multiobjective approach for minimization of injection molding defects

This paper describes a fuzzy multiobjective optimization approach for determining the set‐points of the injection molding processing parameters to minimize the defects formed on the molded parts. The severities of the defects are represented by membership functions using the fuzzy set theory. The minimization of these membership functions, which is a multiobjective optimization problem, is transformed into a substitute problem. The preference function in the substitute problem is original and is proposed specifically for characterizing the quality requirements of the injection molding defects. The formulated optimization problem is solved with design of experiments, in which the process behavior is approximated empirically by a set of quadratic polynomials that can be easily optimized. Experimental results are presented to emphasis the workability of the proposed methodology.     

塑料机器人一模多异腔注射模设计

以塑料机器人产品为载体,介绍异型组合产品的结构工艺性,确定该产品采用一模多异腔的成型方案。基于计算机辅助工程（CAE）数值模拟技术优化模具浇注系统的设计,解决流道填充不平衡的问题;同时在流道上增设特殊结构,解决注塑生产后产品的空间存放问题。根据产品的功能要求,在模具结构中设置抽芯机构,以解决产品成型后产生夹线的工艺问题。该模具在实际的生产过程中取得较好效果,为类似模具的设计提供相关的参考与借鉴。     

基于遗传算法的注塑成型熔接痕长度和位置的优化

提出一个利用遗传算法对熔接痕长度和位置进行优化的方法，目的是使熔接痕的长度最短，且离开用户指定的敏感点最远。将遗传算法和注塑成型软件Moldflow相结合，经设定相关的工艺参数，调用Moldflow模拟分析，提取分析结果，计算目标函数等多个步骤，并按照遗传算法的搜索路径，经过多代搜索，最终获得对应于熔接痕长度与位置最佳的注射时间、熔料温度、模具温度、浇口位置等工艺参数。     

Automated Design for the Runner System of Injection Molds Based On Packing Simulation

Multiple injection cavities are automatically balanced by adjusting runner and gate sizes based on an iterative redesign methodology integrated with computer-aided engineering (CAE) packing simulation. For runner balancing, each cavity must be filled simultaneously at uniform pressure. In addition, the time-pressure history of the polymer melt over the entire molding cycle should be considered. Based on the proposed methodology, a multicavity mold with identical cavities is balanced to minimize entrance pressure differences among various cavities at discrete time steps of the molding cycle. The results have shown more than a 95% reduction of the entrance pressure differences over other related studies, and also have demonstrated increased searching performance over other optimization techniques. A family mold with different cavity volumes and geometries is also balanced to minimize pressure differences at the end of the melt flow path in each cavity on a basis of discrete time steps of the molding cycle. The methodology has shown uniform pressure distributions among the cavities during the entire molding cycle.     

手机后盖注塑工艺及模具优化设计

运用Moldflow软件对手机后盖进行了模拟分析,优化了浇口位置,并针对成型过程中出现的缺陷进行了工艺参数优化,在模拟结果的基础上对注塑模具进行了优化设计。CAE优化与模具设计的有效结合,缩短了模具研发周期,降低了产品开发成本,提高了产品质量。     

Resin transfer molding process optimization using numerical simulation and design of experiments approach

The art of resin transfer molding (RTM) process optimization requires a clear understanding of how the process performance is affected by variations in some important process parameters. In this paper, maximum pressure and mold filling time of the RTM process are considered as characteristics of the process performance to evaluate the process design. The five process parameters taken into consideration are flow rate, fiber volume fraction, number of gates, gate location, and number of vents. An integrated methodology was proposed to investigate the effects of process prameters on maximum pressure and mold filling time and to find the optimum processing conditions. The method combines numerical simulation and design of experiments (DOE) approach and is applied to process design for a cylindrical composite part. Using RTM simulation, a series of numerical experiments were conducted to predict maximum pressure and mold filling time of the RTM process. A half‐fractional factorial design was conducted to identify the significant factors in the RTM process. Furthermore, the empirical models and sensitivity coefficients for maximum pressure and mold filling time were developed. Comparatively close agreements were found among the empirical approximations, numerical simulations, and actual experiments. These results were further utilized to find the optimal processing conditions for the example part.     

车用CD托架CAE注塑工艺参数优化分析

以汽车CD托架注塑成型为例,结合生产实际问题,构建了产品CAE分析模型,运用Moldfl ow2015软件对产品材料推荐的注塑成型工艺参数进行了初步仿真,对注塑过程中的翘曲、熔接痕、气穴等缺陷成因进行了分析,并给出了质量改善优化目标,提出了一种结合Taguchi试验法、BP神经网络预测的注塑成型工艺寻优方法,并对寻优结果进行了CAE模流分析验证。结果表明,神经网络预测结果与CAE模流分析结果相近,产品翘曲量降低至1.192 mm,产品较佳的注塑成型工艺参数为:料温为225℃,模温为60℃,注塑压力为70 MPa,注塑时间为1.3 s,第一保压压力为80 MPa,第一保压时间为12 s,第二保压压力为30 MPa,第二保压时间为3 s,冷却时间为15 s,型腔随形水路C1,C2冷却水的温度均为30℃。提出的优化设计方法能有效降低模具试模成本,缩短模具生产周期。     

基于计算机仿真的注塑成型工艺优化研究

为了优化注塑成型工艺,研究了注塑成型的数学模型,以及产生翘曲形变的原因,在此基础上利用Moldflow软件对薄壁件塑料注塑成型过程中的宽浇口平板进行了仿真实验,并采用了无定型塑料丙烯腈-丁二烯-苯乙烯共聚物+聚碳酸酯(ABS+PC)对其进行注射、保压、冷却等流程模拟,选定了保压压力、熔体温度、冷却时间、模具温度、注射时间、保压时间等主要工艺参数,并通过方差比较的方法对这些工艺参数进行了评价,最终确定了注塑成型的优化方案。通过实验得出了ABS+PC的最优工艺参数组合,有效降低薄壳制件的翘曲量并优化了其制品性能。     

基于DOE实验的汽车塑件CAE优化与注塑模具设计

以某汽车塑件为例,针对其结构及分型复杂、注塑难等问题,基于DOE实验和CAE分析对其注塑所需工艺参数进行了仿真和优化。通过浇口位置和数量的优化,获得了理想的浇口设置;通过浇注系统的优化及成型窗口分析,获得了合理的流动分析工艺参数;对流动分析工艺参数进行正交试验优化,找出了产品注塑存在的潜在缺陷问题,经进一步对针阀控制进行寻优,解决了熔接线过长过多、充填不平衡、气孔较多等问题;通过翘曲和冷却分析的优化,最终获得了产品注塑成型所需的合理工艺参数,设计了一副结构合理的注塑模具,提高了模具生产效率。     

Analysis of the vacuum infusion molding process

The vacuum infusion molding process is becoming increasingly popular for the production of large composite parts. A comprehensive model of the process has not been proposed yet, making its optimization difficult. The flexible nature of the vacuum bag coupled to the varying pressure inside the mold cavity results in a variation of the cavity thickness during the impregnation. A complete simulation model must incorporate this phenomenon. In this paper, a complete analysis of the vacuum infusion molding process is presented. The analysis is not restricted to the theoretical aspects but also reviews the effect of the main processing parameters. The parameters investigated in this paper are thought to be those of most interest for the process, i.e. the compaction of the reinforcement, the permeability, the infusion strategy and the presence of flow enhancement layers. Following the characterization experiments, a 1‐D model for the vacuum infusion molding process is presented. This model is derived assuming that an elastic equlibrium holds in the mold cavity during mold filling. Even though good agreement was found between simulation results and experiments, it is concluded that additional work is needed on the numerical model to integrate interesting findings from the experimental part.     

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。     

医用皮囊注塑模具的CAE优化设计

针对软塑料制品——医用皮囊在注射成型过程中形成的顶部变形缺陷问题,运用Moldflow的MPI(MoldflowPartInsight)软件进行了准确的CAE模拟和分析,并在模拟结果的基础上对注塑模具进行优化设计,得到改善成型缺陷的新方案。新方案的CAE模拟结果显示能够有效解决原有的成型缺陷问题,从而验证了优化方案的可行性。运用CAE技术可以为提高精密制品质量和优化成型工艺提供有效的指导和辅助手段。     

基于统一网格的塑件成型与模具结构一体化分析

针对精密注射成型对模具变形准确预测的需求,基于CAD模型生成了统一的塑件成型分析与模具结构分析网格,实现了成型分析结果数据到结构分析的无缝输入。利用自主开发的注射成型过程仿真系统和ANSYS软件,进行了一体化分析研究。针对某型号航天产品的研发,分别开展了模具在最大注射压力、热应力及二者共同作用下的模具变形CAE分析,有效校核了模具的刚度,保证了产品的顺利成型与尺寸精度。     

基于Moldflow的电子镇流器底壳注射成型分析

利用Moldflow软件对电子镇流器底壳注射成型过程中最佳浇口位置和流动情况进行分析,确定了最佳浇口位置。通过对填充时间、气穴、熔接痕、锁模力曲线和流动前沿温度等数值模拟,预测塑件可能出现的缺陷,显示了Moldflow技术在模具开发过程中对于优化塑料注射模设计和优化注射工艺参数等方面所起到的显著作用。     

一种单腔双色多功能注塑模具设计

介绍了一种特殊的单色、双色集成式家族两板注射模具。模具的布局为1模2腔,其中的一个单色模腔用于塑件的单色注射成型,另一个单腔双色模腔用于塑件的双色注射成型。单腔双色模腔只用一个模腔即能实现塑件的双色注射成型,其功能实现的方式为：在单色模腔的基础上,通过改变型腔镶件的形状及位置、以及第二胶浇口成型件的位置,达到单腔进行双色注射成型的目的。结合浇注系统的改造,模具能实现5种注射成型功能,分别为：单色塑件单腔注射功能、单色塑件双腔注射功能、单腔双色注射功能、单色+双色家族式注射功能,以及单模中注射两种不同颜色的同款塑件。模具结构新颖,简单实用,能有效降低多要求注射成型塑件的模具制造成本,有较好的设计参考价值。     

试论注射模塑件溢边的形成

从注塑设备、模具设计与制造、塑料选材、注塑工艺参数的调节及塑料件的工艺性等方面讨论了造成注射模塑件产生溢边的原因，有助于对症解决溢边问题。