注射模冷却系统的CAE技术应用

注射模冷却系统设计得是否合理，直接影响塑件的尺寸精度和机械性能．传统的设计方法仅适用于形状简单的中小型模具，对于大型、精密和形状复杂的注射模只能利用CAE进行冷却分析才能得到合理的结果．     

An object-oriented approach to computer-aided design of a plastic injection mould

This paper describes a knowledge-based and object-oriented approach for the design of the feed system for plastic injection moulds. The gating system of a plastic injection mould plays a significant role in producing a quality part. Designing of this gating system entails a great amount of effort from an experienced designer and it is time-consuming. CADFEED (Computer-Aided Design of the FEED system of the plastic injection mould) is developed to accurately and efficiently design the type, location and size of a gating system of a plastic injection mould. This system provides an accurate and fast means of obtaining solutions based on the users' requirements, which are easily handled by the rating algorithm in the system. CADFEED generates acceptable solutions at a lower cost than most traditionally and commercially available analysis packages. This system can be used to verify designs proposed by the design engineers. It can also help novice engineers in the understanding of mould design. Another important feature of CADFEED is that it is a low cost system, which uses AutoCAD and an expert system shell on a personal computer. This feature makes CADFEED easily affordable by small-scale industries.     

An Internet-based intelligent design system for injection moulds

The rapid growth of Internet and information technologies in recent years provides a solution to support and facilitate collaborative product developments among different geographically distributed enterprises. An effective and feasible tool to aid the collaborative development of injection moulds can be realized by developing an Internet-based mould design system as one of the modules of a collaborative product development system. This paper presents a prototype Internet-based intelligent design system for injection moulds. The architecture of the system consists of an interactive KB mould design system embedded in an Internet environment. A Java-enabled solution together with artificial intelligence techniques is employed to develop such a networked interactive CAD system. In this system, the computational module, the knowledge base module and the graphic module for generating mould features are integrated within an interactive CAD-based framework. The knowledge base of the system would be accessed by mould designers through interactive programs so that their own intelligence and experience could also be incorporated with the total mould design. The approach adopted both speeds up the design process and facilitates design standardization which in turn increases the speed of mould manufacture. A practical case study is presented to illustrate the operations of the Internet-based mould design system.     

Thermoforming mould design using a reverse engineering approach

Thermoforming is commonly used to produce shaped plastic sheets for packaging consumer products. The conventional method of designing and making thermoforming moulds is laborious and time consuming. A method based on a reverse engineering approach and thermoforming feature concept is proposed. The method involves the use of a self-developed device to digitise the surface of a product. A CAD model that corresponds to the thermoforming mould of the product is then constructed by using the digitised data. The construction of the mould surface is based on the concept of a defined set of thermoforming mould features. A modified Laplacian smoothing technique is applied to process the digitised data for generating the thermoforming mould surfaces. Several examples are used to explain the working principle and demonstrate the viability of the proposed method.     

基于Solidworks开发机械制图虚拟模型库

随着计算机、网络和多媒体技术的迅猛发展,为了适应科技教学、网络教学的需要,利用先进的多媒体技术构建《机械制图》虚拟模型库,优化教学资源,丰富教学手段,制作方法主要采用了国际上流行的三维实体设计软件SolidWorks进行模型造型,采用网页设计软件Dreamweaver MX组织模型库框架,该模型库可以根据教学需要及时地添加、更换、修改和完善模型库中的模型。同时,库中的模型可以随意翻转、移动、拆装和仿真运动。具有很好的教学演示效果。在使用、携带、保管和成本等方面都有着传统模型无法比拟的绝对优势。     

Case study: A novel surface scanning system

This paper presents the design and development of a novel surface scanning system that employs an array of 144 equal spaced probing pins for capturing the surface coordinates of an object simultaneously. Operation of the system is computer driven. The captured surface data is saved in a point‐cloud data file, which can be postprocessed by a CAD system to construct a surface model of the scanned object. The created CAD model can be used to facilitate the design and making of thermoforming moulds. The thermoforming moulds are to be used for forming plastic sheets for packaging consumer products for retail selling. A prototype of the system has been built. Test results demonstrate that the developed system can satisfy the technical and economical requirements of the packaging industry. © 2005 Wiley Periodicals, Inc.     

基于模具的手写数字串切分算法及其应用

提出了一种基于模具的手写数字串切分算法,该算法通过总结手写数字串中字符之间的连接特点,归纳出一套合理的切分曲线类型,并根据这些曲线类型设计出多种切分模具,从而将字符的切分过程变为各种模具的试用和优选过程．通过在银行票据OCR系统中的应用,验证了算法的有效性．     

基于CAD/CAE的卡扣模具快速设计与优化

为提高塑料卡扣模具设计的速度,利用ImageWare对塑料卡扣进行点云数据处理、特征线网格划分和曲面重构;将重构的塑料卡扣模型导入UG,借助UG的曲面修复功能缝合不连续的曲面,并以STL格式保存;利用UG的Mold Wizards模具设计模块,根据已保存的STL格式卡扣模型建立模具装配模型,设计分型面,生成模具成型零件的三维实体模型;用Moldflow/MPI进行塑料卡扣注射成型分析.结果表明采用优化后的模具设计参数与实验结果基本吻合。     

1-3 Piezocomposites realised from small feature size, high aspect ratio, hot embossed moulds. Part II: piezocomposite fabrication

1-3 Piezocomposites offer many advantages over monolithic transducers, however replicating their fine scale structure is demanding. Viscous polymer (VP) embossing is a technique that has already been demonstrated as being capable of achieving the small feature size and high aspect ratio features that are required for piezocomposites. However, the process utilises a lost mould technique and is therefore limited by the ability to make cost effective sacrificial moulds. Hot embossing has been identified as a technique that is suitable for replicating these moulds, and piezocomposites made from them are presented here. This paper dimensionally characterises the piezocomposites through each stage of the VP embossing process. The piezocomposites described here have feature sizes of 30 μm, volume fractions 0.5 and operating frequencies of 12.3 MHz. For the first time piezocomposites have been made by VP embossing into cost effective moulds.     

1-3 Piezocomposites realised from small feature size, high aspect ratio, hot embossed moulds. Part I. Mould development

1-3 Piezocomposites offer many advantages over monolithic transducers, however replicating their fine scale structure is demanding. Viscous polymer (VP) embossing is a technique that has already been demonstrated as being capable of achieving the small feature size and high aspect ratio features that are required for piezocomposites. However, the process utilises a lost mould technique and is therefore limited by the ability to make cost effective sacrificial moulds. Hot embossing has been identified as a technique that is suitable for replicating these moulds, and piezocomposites made from them are presented here. This paper dimensionally characterises the piezocomposites through each stage of the VP embossing process. The piezocomposites described here have feature sizes of 30 μm, volume fractions 0.5 and operating frequencies of 12.3 MHz. For the first time piezocomposites have been made by VP embossing into cost effective moulds.     

An integrated manufacturing system for rapid tooling based on rapid prototyping

To reduce the time and cost of moulds fabrication, a novel integrated developing and manufacturing system of rapid tooling (RT) based on rapid prototyping (RP) is proposed. The architecture of system which consists of four building blocks: digital prototype, virtual prototype (VP), physical prototype and RT system, is presented. A digital prototype can be established by 3D CAD software packages or reveres engineering technique. A VP is employed to guide in optimization of the mould design and manufacturing process planning. A physical prototype, which is built using RP technology, generally serves as a pattern for producing RT. By integrating these building blocks closely, the system can aid effectively in mould design, analysis, prototyping, simulating, and manufacturing process development. Three typical cases are discussed in detail to illustrate the application of the system. It has been shown from a number of case studies that the system has a high potential to reduce further the cycle and cost of die development while minimizing error introduction. As a result, the integrated system provides a feasible and useful tool for companies to speed up their product development.     

Replication quality of micro structures in injection moulded thin wall parts using rapid tooling moulds

Injection moulding of micro structured polymer parts is often limited due to the replication quality of the structured surfaces. To enhance the replication quality process parameters, e.g., pressure, temperature or injection velocity, are adapted. Here, the mould temperature is the most important factor. This paper investigates the influence of the mould temperature on the replication of micro structured surfaces using amorphous and semi-crystalline polymers. Using rapid tooling moulds and a dynamic tempering system allows mould temperatures about the solidification temperatures during injection and a sufficient cooling for save ejection of the part. The results reveal that for amorphous polymers the mould temperature should be above the glass transition temperature for high replication quality. For semi-crystalline polymers the high cooling velocity seems to inhibit the crystallization process and this leads to a sufficiently low viscosity to achieve high replication quality.     

虚拟塑料注塑成型教学系统

塑料注射成型技术的发展与注射模具设计人员需求的增长十分迅速，模具设计人员学习必要的塑料成型基本原理是掌握注射模具设计方法的现实需要。该文在虚拟现实（VR）技术的基础上，结合基于三维模型的注塑成型FEA技术、面向对象的编程技术和OpenGL图形库，研究并实现了沉浸式、交互式的虚拟塑料注射成型教学仿真系统（VPIM），提出了立体成像算法，给出了模拟注射成型过程运动仿真的方法，借助VR外设及通过建立知识化、数字化、可视化、现实化的教学平台来提高设计人员的学习效率、学习兴趣及对问题理解的深入程度。     

Visibility-based conformal cooling channel generation for rapid tooling

In plastic injection moulding process, cooling channel design is an essential factor that affects the quality of the moulded parts and the productivity of the process. Non-uniform cooling or long cooling cycle time would result if a poorly designed cooling channel is adopted. Due to limitations of traditional machining processes, the cooling channel is usually formed from straight-line drilled holes and only simple shapes are allowed, regardless of the shape complexity of the part being moulded. With the advent of rapid tooling technology, cooling channels in complex shapes can now be possible. However, there are not many design methodologies for supporting this type of cooling channel. In this paper, a methodology called visibility-based cooling channel generation is proposed for automatic preliminary cooling channel design for rapid tooling. The cooling process between a mould surface and a cooling channel is considered analogous to whether they can be visible from each other. Without loss of generality, the mould surface is approximated by a polyhedral terrain and is normally offset. A number of point light sources together that can illuminate the whole polyhedral terrain are assigned to suitable terrain offset vertices. A cooling channel is then generated by connecting all the assigned light sources. When comparing the conventional verification and redesign methods by melt flow analysis, computer-aided design and, a better design of cooling channel for its mould surface results in a short time independent of the experience of mould engineer.     

A feature-based approach to injection mould cooling system design

Most existing work on the design of cooling systems of plastic injection moulds has been focused on the detailed analysis or the optimization of the cooling system. However, before a cooling system can be analysed or optimized, an initial design has to be developed. We explore a new design synthesis approach to solve this initial design problem. A plastic part with a complex shape is decomposed into simpler shape features. The cooling systems of the individual features are first obtained, they are then combined to form the cooling system of the entire part. Decomposing a complex shape into shape features is a feature recognition problem. A new algorithm for the recognition of features specific to cooling system design is developed. Design examples generated by the design synthesis process are analysed by C-Mold to verify the feasibility of the approach.     

A computer-aided prototype system for NC rough milling of free-form shaped mechanical part-pieces

A prototype computer-aided manufacturing module for rough milling of free-form mechanical moulds is proposed. The system allows direct modelling of the shape of the material to be removed, by starting from the geometry of the stock and of the final part-piece. A modelling engine, based on rational bivariate and trivariate tensor-product B-spline patches, was developed to ensure complete geometric coverage, allowing common analytic geometric items such as planes, quadrics, and blocks to be exactly modelled. Methods for the evolution of the milling layers, the choice of isoparametric NC tool-paths and their piecewise approximation are proposed; the procedures work in the context of three-axis machining by end-mill cutters. Technological considerations about the main cutting force the follow: it results that fine tuning of the milling feed rate can be computed by geometric evaluation of the depth and width of cut. To demonstrate the feasibility of the approach, an application example concerning mould manufacturing is reported.     

Mapping of tubular woven composite preforms on to doubly-curved surfaces

This paper deals with the drape behaviour of tubular woven fabric hoses over doubly curved mould surfaces. The primary aim of this analysis is to predict the alignment of the constituent fibres over the mould surface, which in composites-based applications directly influences the quality of the final product in terms of its structural homogeneity and mechanical properties. Previous work in the area has resulted in algorithms to map the fibres of a flat woven fabric over open surfaces using the shear deformation theory of a woven lamina. The present paper first applies these algorithms to map a flat fabric on to a doubly curved tubular surface and determines the outline of an equivalent tubular fabric preform needed to cover the surface. It is noted that using such a mapping, even to produce a simple u-bend tube requires the tubular preform to have varying cross-section, which is difficult to manufacture. Subsequently, specific algorithms are developed to map a straight tubular hose over a bent and twisted tubular section. Using basic principles of mechanics, models have been derived to map the mesh of fibres over geodesic paths on the curved surface. It is noted that shear deformation plays little or no role but fabric extension and buckling play major roles. The resulting mapping algorithm has been applied to several shapes of varying complexity and experimental validations have been performed.     

Energy efficiency benchmarking for injection moulding processes

Energy and resource efficiency is becoming an important strategy in manufacturing. In the automotive industry, the assessment of the environmental impact of a product in use-phase is common practice. In contrast, the manufacturing phase often lacks detailed data; potential for improvement gets lost. Analysis and comparative evaluation of how the production factor energy is used in manufacturing can be an impulse for parallel improvements regarding energy, material and process time efficiency. The paper presents a systematic approach to energy efficiency benchmarking in injection moulding, specifically addressing the impact of the mould. A knowledge base serves as a baseline for the process of data collection and evaluation. Additionally, energy efficiency benchmarking of single processes give insight into the effectiveness of improvement measures and allow to identify best practice process and product designs. The concept can be extended to predict energy consumption of production plants. An energy label for moulds is introduced.     

基于模型检索的玻璃瓶模具组件设计方法与实现

在分析玻璃瓶罐产品结构与企业模具设计标准的基础上,在 NX 环境下提出基于 模型检索的玻璃瓶模具组件设计方法。采用极半径不变矩的图像识别算法进行特征识别,以瓶 罐产品信息作为侧向索引,构建了包含玻璃瓶模型特征以其对应模具组件方案的实例库。在实 例库中对相似模型进行检索与匹配,再以系统知识库中的专家知识与经验对匹配成功的相关组 件进行设计。以 400 ml 广口瓶的初型模和成型模设计案例验证了该设计方法的可行性。     

基于多元决策模型的结晶器协调控制方案

针对在特定物理环境、经济环境和工程环境下,如何选择最佳的结晶器协调控制方案的问题,提出一种新的控制方案分析方法:基于多元决策模型的模糊分析方法.根据连铸工业过程对结晶器控制系统的要求,选取鲁棒性、超调量、能量消耗率、安全性、安装成本、复杂性等6个指标建立综合评估体系,采用判断矩阵法确定多元决策权重向量,进而构造出控制系统评价优选的多元决策模型.基于该模型,在多元约束条件下对4种典型的结晶器协调控制方案及其仿真结果进行了模糊分析.分析结果对实际结晶器控制系统的设计有指导性意义.该方法可以推广到其他控制系统的方案评估中去.