Manufacturing multi-material articulated plastic products using in-mold assembly

In-mold assembly can be used to create plastic products with articulated joints. This process eliminates the need for post-molding assembly and reduces the number of parts being used in the product, hence improving the product quality. However, designing both products and molds is significantly more challenging in case of in-mold assembly. Currently, a systematic methodology does not exist for developing product and processes to exploit potential benefits of in-mold assembly for creating articulated joints. This paper is a step towards creating such a methodology and reports the following three results. First, it presents a model for designing assemblies and molding process so that the joint clearances and variation in the joint clearances can meet the performance goals. Second, it describes proven mold design templates for realizing revolute, prismatic, and spherical joints. Third, it describes a mold design methodology for designing molds for products that contain articulated joints and will be produced using in-mold assembly process. Three case studies are also presented to illustrate how in-mold assembly process can be used to create articulated devices.     

A virtual injection molding system based on numerical simulation

CAD and CAE have now become very popular in injection molding development. Integration with virtual reality is a new boost to these fields. This paper presents a research effort targeting the creation of a desktop-based, low-cost and independent virtual injection molding system, which is implemented based on the techniques such as virtual reality, finite element analysis, motion simulation and scientific visualization. With the stereoscopic display of the mold design and motion, the system provides engineers a cohesive view of mold structure and assembly. And by analyzing the numerical CAE results, the possible faults during molding process can also be highlighted. With this integration, the overall system would be a new powerful tool to mimic the real process of injection molding and evaluate various influences from product design to manufacturing, capable, therefore, of improving the moldability and the quality of molded products.     

Development of a concurrent mold design system: a knowledge-based approach

This paper presents research that establishes a systematic methodology and knowledge base for an injection-molding mold design in a concurrent engineering environment. This methodology is, in general, analogous to the methods of design for manufacturing, and is, however, in collaboration with activities of molding product design and mold manufacturing process planning. The practical goal of this research is twofold: to develop a mold-development process that facilitates concurrent engineering-based practice and to develop a knowledge-based design aid for injection-molding mold design that accommodates manufacturability concerns, as well as requirements of products. The research approach includes (i) process modeling and reengineering for concurrent mold design, (ii) identification of functional requirements with a computer-based system, (iii) system framework design, and (iv) system modeling and implementation. The framework supports concurrent engineering based mold design by providing advisory tools that are able to resolve relevant issues at the early stages of mold design. The results of this research will facilitate the rationalization and automation of the mold development process, thus improving the efficiency and quality of, and reducing the cost of, mold development.     

CAE与塑料成型质量分析

塑料模具的设计不但采用CAD技术,而且还要采用CAE技术,这是发展的必然趋势。CAE技术提供了从制品设计到生产的完整解决方案。在模具制造之前,CAE技术可以预测塑料熔体在型腔中的整个成型过程,帮助研判潜在的问题,有效地防止问题发生,并能缩短产品的开发周期,降低生产成本。本文从一个生产实例出发,用Moldflow软件对该制品的注射成型方案进行分析比较,从而找到解决制品质量问题的途径。     

A nondestructive online method for monitoring the injection molding process by collecting and analyzing machine running data

Nondestructive online monitoring of injection molding processes is of great importance. However, almost all prior research has focused on monitoring polymers in molds and damaging the molds. Injection molding machines are the most important type of equipment for producing polymeric products, and abundant information about actual polymer processing conditions can be obtained from data collected from operating machines. In this paper, we propose a nondestructive online method for monitoring injection molding processes by collecting and analyzing signals from injection molding machines. Electrical sensors installed in the injection molding machine, not in the mold, are used to collect physical signals. A multimedia timer technique and a multithread method are adopted for real-time large-capacity data collection. An algorithm automatically identifies the different stages of the molding process for signal analysis. Moreover, ultrasonic monitoring technology is integrated to measure the cavity pressures. Experimental results show that our nondestructive method can continuously monitor the injection molding process in real time and automatically identify the different stages of the molding process. The packing parameters, including the filling-to-packing switchover point and the packing time, can be optimized based on these data. Furthermore, the ultrasonic reflection coefficient and the actual cavity pressure have similar trends, and our technique for measuring the cavity pressure is accurate and effective.     

A methodology to define a reconfigurable system architecture for a compact heat exchanger assembly machine

Due to the unexpected, fast, and constant changes of market requirements and the hypercompetency, robust manufacturing systems are needed that adjust easily to operational variability and the customized product supply. The simply substitution of components, software, hardware, and/or their adaptation by parameters resetting are an attractive option to face this challenge. Short product life cycles are an undeniable consequence and evidence of this. For this reason, to develop products or services profitably in the product manufacturing field, it is common to use the product family concept, which involves sharing components, functional features, and manufacturing process, both to make a cheaper product development process and to obtain customized products. A new generation of manufacturing systems that deploy characteristics such as adaptability and flexibility responding to the market dynamics called reconfigurable manufacturing systems (RMS) are required by market according to manufacturing experts. The manufacturing systems with modular architecture are the best way to meet flexible and adaptable RMSs because they allow reconfiguration by a simple module substitution or by resetting module operation parameters. This paper presents a design methodology developed to obtain modular RMS. The method integrates the utilization of modular architecture principles, selection algorithms (analytical hierarchical process), clustering algorithms (average linkage clustering algorithm), family product features and functional system analysis in the classical product design process. The methodology proposed allows defining the most adequate modular system architecture and the modular definition of the reconfiguration variables that are needed to reach the flexibility required. A real study case about a heat exchanger assembly machine is presented where this methodology is applied in order to present an evidence of its usefulness.     

数理统计在模具生产制程能力分析中的应用

用数理统计精确度指标CPK对模具生产的制程能力进行分析.按照CPK值将模具的制程能力划分为5个等级,并以5个尺寸的32组抽样数据为例,得出CPK等级在A级时,模具生产的准确性和精密度较高,可以生产出优质产品,无需对模具和成型工艺参数做任何修改;当CPK等级不在A级时,结合准确度和精密度的情况,给出了相应的模具及成型工艺参数的整改方案.     

Virtual plastic injection molding based on virtual reality technique

Virtual reality (VR), as a new technology, is integrated with software systems for engineering, design, and manufacturing. The integration has given a new impetus to the field of computer-aided engineering. This paper presents a research effort aimed at creating a virtual plastic injection molding (VPIM) environment, which is designed and implemented based on techniques such as VR, multidiscipline simulation, and scientific visualization. The VPIM system includes two parts: designing in VPIM and evaluation in VPIM. It is the first system to scrutinize virtual prototype mock-ups of new products, machines and production processes in interactive graphic simulation. During the evaluating phase, coupled to appropriate computer-based reasoning and decision-support tools and driven by data from the real manufacturing environment, a realistic impression of the process of plastic injection molding and manufacture can be achieved and can be changed interactively, and it is possible to thoroughly examine the planned system and eventually detect and remove any defects and inadequacies. The construction approach and key techniques (FEA, virtual assembly, stereoscopic display, a triangulated boundary-representation of an approximating polyhedron, collision detection, etc.) of the system are described in detail. The overall system is a powerful new approach for highly relevant industrial application of VPIM which focuses on the construction and assessment of alternate manufacturing sequences and mold design in an early design stage. Improvement of the design and manufacturing process will lead to better design and reduced development time and cost.     

UG在注塑模具设计与加工中的应用

当前模具制造业正处于一个品种繁多的大量生产状态,以适应国内外市场迅速变化的要求。数控技术及CAD/CAM技术的迅速发展使传统的模具设计与制造方式发生了根本性变化。现结合实际注塑模具的设计与加工阐述UG在注塑模具中的应用。它的应用可大大缩短模具的交付时间,为企业降低生产成本提供一个有效的手段。     

基于Moldflow的连接件注射成型浇口的模拟与分析

运用Moldflow软件计算得出连接件的体积,并采用Moldflow软件分析出连接件的最佳浇口位置,对该塑件进行了模拟填充、冷却并且确定气泡、熔接痕的位置,从而确定塑件的成型性能和产品的质量,确定出连接件浇注时候所选择的浇口类型,所得结果可以帮助预知模具结构可能存在的问题,从而优化模具结构,节约生产成本,提高生产率.Moldflow模拟为模具设计提供了重要的参考.     

Study on temperature field for invar alloy during TIG welding

In order to solve the complex multi-objective optimal performance design of large-scale injection molding machines, NSGA-II is used to find a much better spread of design solutions and better convergence near the true Pareto-optimal front. The combination of the design method and the injection molding machine is discussed. Screw diameter performance, stick inside distance performance, mold moving route performance and mold-locked force performance are chosen as the four main performance evaluation indexes. Some related parameters are associated to get a performance indication. And performance optimization design parameter constraints are listed to make the design solutions to have practical significance. The mathematical models of two objectives and the mathematical models of three objectives are analyzed. Finally, the instance of HTF180X1N large-scale injection molding machine is taken as an example to demonstrated that such method is effective and practical.     

基于模拟的注塑工艺分析设计集成系统的开发

将模具设计、制造和注塑工艺作为模具设计开发过程中的三个重要因素 ,提出了在模具设计阶段并行地进行注塑工艺方案设计的思想。开发了一套基于 C- MOL D系统的注塑工艺方案设计系统 ,该系统是基于并行设计思想 ,集成了 CAD和注塑过程 CAE分析系统部分信息的新平台 ,为在模具设计阶段进行注射工艺方案的并行设计和在注射工艺方案设计阶段进行工艺方案评价提供了一个集成环境     

Integrated simulation of the injection molding process with stereolithography molds

Functional parts are needed for design verification testing, field trials, customer evaluation, and production planning. By eliminating multiple steps, the creation of the injection mold directly by a rapid prototyping (RP) process holds the best promise of reducing the time and cost needed to mold low-volume quantities of parts. The potential of this integration of injection molding with RP has been demonstrated many times. What is missing is the fundamental understanding of how the modifications to the mold material and RP manufacturing process impact both the mold design and the injection molding process. In addition, numerical simulation techniques have now become helpful tools of mold designers and process engineers for traditional injection molding. But all current simulation packages for conventional injection molding are no longer applicable to this new type of injection molds, mainly because the property of the mold material changes greatly. In this paper, an integrated approach to accomplish a numerical simulation of injection molding into rapid-prototyped molds is established and a corresponding simulation system is developed. Comparisons with experimental results are employed for verification, which show that the present scheme is well suited to handle RP fabricated stereolithography (SL) molds.     

气冲气推成形触头造型机的试验研究

介绍了一种新发明的气冲气推成形触头造型机实砂机构。它于同一工位、同一工序、用同一动力,实现了气冲紧实与成形触头冲击紧实同时并举。阐述了其实砂过程及实砂机理。试验表明,气冲气推成形触头造型机的实砂效果十分理想,砂型紧实度高而且均匀,完全克服了目前单纯气冲造型技术中存在的弊端,拓宽了气冲造型机的适用范围。这是一种机构简单、投资少、高速、高效、低能耗的造型实砂机构。     

电热式变模温注塑模具热响应辅助分析程序开发

针对快速变模温注塑成型模具热响应分析复杂问题,对电热式变模温注塑模具热响应作了研究,采用随形加热系统设计方法,将复杂的电热式变模温注塑模具简化为单个加热细胞单元,以电热元件的规格和布局为设计变量,以加热时间和型腔表面温差为热响应指标,结合Matlab图形界面开发模块和ANSYS有限元分析软件,开发了基于加热细胞单元的电热式变模温注塑模具热响应辅助分析程序,并对其准确性做了验证分析。研究结果表明,该辅助分析程序可以较好地预测模具的加热效率和型腔表面温度均匀性,可为电热式变模温注塑模具的设计、分析一体化提供一条快捷和高效的途径。     

一种快速制作栅格天线的新型解决方案

文中以一种树脂基碳纤维复合材料栅格天线反射面的制作成型为研究对象,详细阐述了该反射面成型后脱模模具工装的设计及成型方案。该栅格反射面所使用的主要材料为东丽公司的T700,基体为3234树脂体系。通过对复合材料模具的设计制作及使用、复杂复合材料制品二次脱模等方面的研究,提出了用球墨铸铁及碳纤维复合材料制造模具、采用真空袋热压罐成型工艺的新型解决方案。结果表明：与传统金属模具相比,在较大温差下复合材料模具具有尺寸精度更稳定、制作更简便、重量更轻等优势;利用复合材料过渡模具实现栅格反射面二次脱模可以大大提高生产效率。该方法对此类栅格反射面的制作具有指导意义。     

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.     

小口径非球面玻璃透镜模压成形

随着消费电子行业的增长和人们对轻便易携带的高性能产品的需求,非球面玻璃透镜的需求量持续增长。与传统冷加工方法相比,模压成形技术因具有低成本、批量生产的能力而成为一种更有前途的加工方法,尤其适合中小口径非球面透镜的生产。非球面玻璃透镜的模压成形技术是一项涉及玻璃材料、超精密模芯加工、镀膜、模压成形工艺及成仿真等诸多领域的综合技术。因此,有必要对其中影响成形质量的关键技术进行系统分析和深入研究,探讨模压成形技术现状和存在的问题。对光学玻璃的物理化学性质、主要构成成分、粘弹性、低熔点及环保的发展趋势、预形体的选择进行综合分析;对模芯材料的开发、非球面模芯的单点金刚石车削技术、纳米磨削技术、超精密研抛技术、复合加工技术、镀膜材料、镀膜技术做了详细介绍;阐述模压成形技术及仿真技术的研究现状及最新进展;并对未来发展趋势进行预测与展望。     

Structural scheme optimization design for the stationary platen of a precision plastic injection molding machine

The current development of precision plastic injection molding machines mainly focuses on how to save material and improve precision, but the two aims contradict each other. For a clamp unit, clamping precision improving depends on the design quality of the stationary platen. Compared with the parametric design of stationary platen, structural scheme design could obtain the optimization model with double objectives and multi-constraints. In this paper, a SE-160 precision plastic injection molding machine with 1600 kN clamping force is selected as the subject in the case study. During the motion of mold closing and opening, the stationary platen of SE-160 is subjected to a cyclic loading, which would cause the fatigue rupture of the tie bars in periodically long term operations. In order to reduce the deflection of the stationary platen, the FEA method is introduced to optimize the structure of the stationary platen. Firstly, an optimal topology model is established by variable density method. Then, structural topology optimizations of the stationary platen are done with the removable material from 50%, 60% to 70%. Secondly, the other two recommended optimization schemes are given and compared with the original structure. The result of performances comparison shows that the scheme II of the platen is the best one. By choosing the best alternative, the volume and the local maximal stress of the platen could be decreased, corresponding to cost-saving material and better mechanical properties. This paper proposes a structural optimization design scheme, which can save the material as well as improve the clamping precision of the precision plastic injection molding machine.     

模具设计制造中逆向工程技术的应用

在制造行业领域中,逆向工程技术是一种常用的自主设计制造手段。特别是在实际的模具设计制造过程中,应该将CAD软件作为主要平台来进行合理地逆向设计,这样做能够保障模具产品的优良性能,有效缩短模具制造周期,实现产品质量提高,从而使其不断适应市场需求。