Interference verification of injection molds on the web-based CAD viewer

As the interference between mold parts occurs in a small region, it is difficult to find the interference at the design stage. It is usually found at the assembly stage of injection molds, which delays both design and manufacturing leadtimes. Commercial CAD systems with interference inspection functions have been used so far. However, they are very expensive for the mold industry, and inadequate for performing collaborative work over the Internet. An interference examination system executable on a lower cost CAD viewer is required before releasing final drawings in the mold industry. In this paper, an interference examination algorithm for the Web-based interference verification system applicable to a single-level assembly is studied for injection mold design processes. To design a collaborative system executable on the Internet, a lightweight CAD file converted from a CAD data is used as a native file of the CAD viewer with interference verification capability. The validity of the developed system is confirmed through case studies.     

Data format and browser of lightweight CAD files for dimensional verification over the internet

The demand for the use of 3D CAD data over the Internet environment has been increasing. However, CAD data size has deteriorated the communication effectiveness of 3D CAD files. Good design methodology of a lightweight CAD file is required for rapid transmission on the distributed network environment. In this paper, a file translation system is constructed to produce lightweight CAD files from commercial CAD systems by using InterOp and APIs of the ACIS kernel. Using B-rep models and mesh data extracted from the CAD native files, the lightweight CAD files with topological information are constructed as binary files. As the lightweight CAD files retain topological and geometric information, they are applicable to dimensional verification, digital mock-ups, and visualization of CAD files through a CAD viewer. The effectiveness of the proposed lightweight CAD files is confirmed through various case studies on the CAD viewer. This paper was recommended for publication in revised form by Associate Editor Jooho Choi In-Ho Song received B.S. and M.S. degrees in mechanical engi-neering from Kunsan National University, and Ph.D. degree in mechanical engineering from Hanyang University, Seoul, Korea in 2007. From 2002 to 2007, he served as a team manager to develop CAD and PLM systems in CIES in Korea. He is currently a post-doc researcher in the mechanical engineering department in Hanyang University. As he had developed a lightweight CAD viewing kernel for CAD/CAM systems, he received a New Technology Certificate from Korean Government (MOCIE) in 2005. He also received several prizes from the Korean Society of CAD/CAM Engineers in 2003 and 2004. He specializes in geometric modeling, CAD kernels, product design and digital manufacturing systems. Sung-Chong Chung received the B.S. degree with honors in mechanical engineering from Hanyang University, Seoul, Korea, and the M.S. and Ph. D. in mechanical engineering from KAIST, Seoul, Korea in 1979, 1981 and 1987, respectively. Since 1983, he has been a professor in the School of Mechanical Engineering, Hanyang University, Seoul, Korea. In 2000, he received the outstanding paper award from the North American Manufacturing Research Institution of the Society of Manufacturing Engineers. He received the academic research and software development awards from the Korean Society of Mechanical Engineers and the Korean Society of CAD/CAM Engineers in 2003 and 2004, respectively. His research interests include CAD/CAM, control, mechatronics, manufacturing and precision engineering.     

A feature-extraction-based process-planning system

This paper presents an automatic features-extraction and process-planning system using the STEP AP214 file as neutral design data format. A framework is proposed to support integration of CAPP with CAD system. After analyzing the STEP AP214 file, a method for extracting the basic features of part from STEP AP214 of 3D model is proposed. The combination rules of basic features are then studied by identifying feature relationships. Also, an approach to processing tolerance information is proposed by utilizing the CAD system’s self-provided functions of macro recording and editing. Finally, based on the proposed approach, the FEB process-planning system prototype was developed employing the knowledge-based approach and an example is presented to illustrate demonstrate and verify the system.     

一种基于STEP的CAD模型直接分层方法

提出了一种基于产品模型数据交换标准的3维计算机辅助设计实体模型直接分层方法,零件的原始计算机辅助设计模型以产品模型数据交换标准中性文件的格式输入分层系统,系统提取其几何拓扑信息并重建计算机内部几何模型。用户选择零件的制作方向并指定分层厚度后,系统自动对计算机辅助设计模型进行直接分层,分层结果可直接送到各种快速成型系统加工。基于产品模型数据交换标准的计算机辅助设计模型直接分层不依赖任何特定的计算机辅助设计系统,通用性、灵活性好,而且产品模型数据交换标准文件的数据量大大小于STL文件,有利于网络化设计与制造环境下的数据传输与交换。     

应用STEP和STEP-NC实现CAD/CAPP系统集成

CAD和CAPP系统的集成一直是一个研究中的难题，其原因在于由于信息表达的不一致，使CAPP系统需要针对不同的CAD系统设计专门的信息提取模块，而对于CAPP下游来说，CAM也不能利用全部的产品设计和工艺信息。STEP标准作为CAD系统的输出，可以为OAPP系统提取信息提供一个统一的接口。而STEP—NC作为新一代数控标准，继承了STEP标准的属性，可以作为CAD／CAPP／CAM／CNC集成的桥梁。应用STEP中性文件，CAPP提取产品的制造特征和加工工步，生成工艺文件，并以STEP—NC中性文件形式输出，便于后续CAM和CNC系统的调用，从而达到CAD／CAPP／CAM／CNC信息集成的目的。     

XML-based assembly visualization for a multi-CAD digital mock-up system

Using a virtual assembly tool, engineers are able to design accurate and interference free parts without making physical mock-ups. Instead of a single CAD source, several CAD systems are used to design a complex product in a distributed design environment. In this paper, a multi-CAD assembly method is proposed through an XML and the lightweight CAD file. XML data contains a hierarchy of the multi-CAD assembly. The lightweight CAD file produced from various CAD files through the ACIS kemel and InterOp includes not only mesh and B-Rep data, but also topological data. It is used to visualize CAD data and to verify dimensions of the parts. The developed system is executed on desktop computers. It does not require commercial CAD systems to visualize 3D assembly data. Multi-CAD models have been assembled to verify the effectiveness of the developed DMU system on the Internet.     

STEP后处理器的设计及实现

ＳＴＥＰ是ＩＳＯ制定的关于产品数据表达和交换的国际标准。ＳＴＥＰ文件是能够完整地表达产品定义数据的中性交换介质。本文介绍了ＳＴＥＰ后置处理器的设计原理及实现方法，作者运用了ＳＴＥＰ产品数据表达和数据交换的思想，根据ＳＴＥＰ文件结构及符号（Ｔｏｋｅｎ）定义，开发了ＳＴＥＰ的词法分析器并根据不同的应用系统提出了相应的数据转换器的设计思想，从而为进一步实现ＣＡＤ／ＣＡＭ一体化提供一个重要的技术支持     

基于STEP的CAD/CAPP零件信息集成

针对目前应用CAD、CAPP、CAM这些自动化孤岛存在的问题，提出了基于STEP标准的CAD/CAPP集成方案，重点阐述运用面向对象技术及数据库技术从三维CAD输出文件-STEP中性文件中自动提取和识别零件特征的方法。该方法可作为异构CAD系统与CAPP间零件信息传输的接口工具。     

关于STEP中性文件数据结构的研究及实现

STEPq-性文件作为STEP标准最为广泛的应用，成为当下主流CAD／CAM系统无一不支持的输入输出中性格式，无论是实现CAX系统间的数据集成，还是二次开发都需要解读STEP中性文件的信息模型。这里就此给出简要阐述，并介绍了STEP中性文件前后处理器的实现方法。     

基于STEP的机械零件CAD/CAPP的集成方法

在统一的产品信息模型的基础上,采用 Ｓ Ｔ Ｅ Ｐ标准实现产品数据的交换与共享,制定了圆锥 轮的应用协议（ Ｚ Ｃ Ａ Ｐ）,达到 Ｃ Ａ Ｄ／ Ｃ Ａ Ｐ Ｐ系统集成。 Ｃ Ａ Ｄ 系统根据 Ｚ Ｃ Ａ Ｐ建立零件特征模型,输出 Ｓ Ｔ Ｅ Ｐ中性文件。 Ｃ Ａ Ｐ Ｐ系统根据应用协议对 Ｓ Ｔ Ｅ Ｐ中性文件进行后置处理,提取零件信息,制定加工工艺。为了使产品数据操作方便,该系统可以对产品数据进行查阅、修改及 Ｓ Ｔ Ｅ Ｐ文件的重构。     

基于STEP-NC的CAD/CAPP/CNC系统集成技术研究

针对CAD、CAPP、CAM及CNC系统间信息集成和共享的瓶颈问题，在综合分析各系统的不同功能及需求的基础上，依据STEP—NC标准，建立了CAD／CAPP／CNC系统集成模型。在该系统集成模型中，采用STEP中性文件形式描述产品信息，各系统之间通过中性文件实现信息的交换和共享。对系统集成信息模型以及设计特征到制造特征的映射等关键技术进行了研究，为更进一步的CIMS系统集成研究奠定了基础。     

基于STEP的并行产品开发信息集成及设计版本管理技术

分析了并行产品开发的特点,提出了并行产品开发的信息集成框架,并从８６３／ＣＩＭＳ关键技术攻关项目“并行工程”的需求出发,参照ＳＴＥＰ应用协议ＡＰ２１４,建立了并行工程产品特征信息主模型,同时利用ＳＴＥＰ开发工具,通过对ＣＡＤ特征再建模的方法支持ＣＡＤ与ＤＦＭ／ＣＡＰＰ／ＣＡＭ／ＣＡＦＤ的信息集成;利用Ｄｅｌｔａ文件管理工具实现产品数据设计版本管理。     

基于STEP机械零件CAD／CAM集成平台的研究

在ＣＩＭＳ／ＣＥ中，ＣＡＤ，ＣＡＰＰ，ＣＡＭ集成是关键技术之一，现在采用的方法多是采用专用格式文件达到数据的集成与共享。本文论述基于ＳＴＥＰ的集成平台技术，采用单五的产品模型，分系统通过对单五产品模型的操作，达到产品数据的共享与交换。为了满足产品数据操作的方便与灵活性，该平台台要对产品数据进行查询，修改及ＳＴＥＰ文件的重构，并且提供ＳＤＡＩ接口及Ｃ函数的调用，以便于其他系统设计信息存取界面，通过Ｓ     

基于实例和知识的CAD／CAPP集成系统

介绍了一个效率高、实用笥强的基于实例和知识的CAD／CAPP集成系统。本系统基于STEP文件,CAPP系统直接获取CAD中的零件设计信息,实现了CAD、CAPP系统的信息集成与共享,从而在完成零件工作图设计的同时,能产生该零件的加工工艺过程,缩短了零件设计加工周期。零件的加工工艺既可以通过对已存在的实例零件进行变异设计,也可以用专家系统进行创成设计。本文讨论了系统的总体结构、信息集成方法和实例提取算法。     

基于STEP文件的图匹配方法研究

从零件的CAD模型中获取工艺设计所需的加工特征信息是CAPP的基础,也是实现CAPP与CAD集成的关键。研究旨在探讨中等复杂程度的机械零件加工特征识别方法,采取其方法从三维设计软件中得到CAD模型。对该模型输出的STEPAP203文件进行处理,获得面特征及其连接边的凹凸性,得到属性邻接图,将其进行处理得到全凹（或全凸）连接的子图,然后将子图中所有代表毛坯面的节点去掉,剩下的就是各特征对应的特征子图。再按照特征子图匹配法,将每个子图与预先定义的特征图进行匹配,就得到了所需要识别的特征。实例结果显示,该方法简便有效,大大减少了图匹配的计算量。     

支持并行产品开发的数据集成方法研究

并行产品开发的基本支持条件之一是计算机辅助工具之间必须实现信息集成，目前，大多数ＣＡｘ系统仍缺乏支持产品生命周期信息集成的手段，特别是ＣＡＤ与ＣＡＰＰ之间的特征集成，至今仍是一个未解决的难题。ＳＴＥＰ方法的提出为ＣＡｘ／ＤＦｘ集成确定了总体方向。本文根据８６３／ＣＩＭＳ关键技术攻关项目“并行工程”的需求，利用ＳＴＥＰ开发工具，通过对ＣＡＤ特征再建模的方法支持ＣＡＤ与ＤＦＭ／ＣＡＰＰ／ＣＡＭ／ＣＡＦ     

Integration of sketch-based conceptual design and commercial CAD systems for manufacturing

Sketch-based modeling is a very important step towards a complete design process digitalization. For a complete digitalization, integration of sketch-based design modeling and commercial CAD systems is being a necessity. This is because of the need of detailed modification and refinement for the 3D models created by sketching. The integration can speed up the design process and affect competition between companies. In this paper, we present a new method to achieve the integration between sketch-based interfaces and commercial CAD systems by using gesture-based sketch modeling techniques for producing 3D conceptual design models and then translating the 3D models into CAD systems with feature recognition through IGES exchange files. Gesture-based modeling method was used because it works in a similar way to feature-based design approach and it is easy to extract features from its 3D models. IGES file format was used for exchanging 3D geometric model information because it is widely available within commercial CAD systems for data exchange and it also can express features and hierarchy information. 3D models were created with a gesture-based sketch interface for modeling and then information was extracted from it. After that, information was translated into IGES entities which were organized in a specific order in an IGES file. This information can be inputted into commercial CAD systems and recognized as a feature-based model with feature recognition embedded within CAD systems. To evaluate the proposed method, we conducted four case studies. In these case studies, we created 3D models and then transferred them into Autodesk Inventor as a commercial CAD system. After the CAD system recognized the 3D models successfully, we applied some modifications on the 3D models such as changing dimensions, positions and drafting to demonstrate the effective integration.     

Development of a computer-integrated system to support CAD to CAPP

During the 1990s, Computer-Aided Design (CAD) and Computer-Aided Process Planning (CAPP) have emerged as effective means of improving productivity and efficiency, resulting in widespread research work related to CAD and CAPP integration in the hope of achieving seamless data flow among the relevant computer systems. Unfortunately, the efficiency of process planning systems still needs significant improvement due to the problems of design data loss or design data mis-interpretation. This paper attempts to introduce an intelligent computer-integrated system for reliable design feature recognition in order to achieve automatic process planning. Moreover, it describes a rule-based computer-integrated system for recognizing features of components stored as STEP format, analyzing the design files and designing manufacturing processes. In this approach, the STEP design file is used as the information source for generating detailed manufacturing process. The significance of this research is that the product designs with dissimilar formats from various CAD systems can now be interconnected and automatically coded for multiple manufacturing purposes. It presents an effective method that rule-based reasoning is used to create optimal process plans for metal cutting.     

支持动态集成的产品数据管理Web服务架构

基于产品模型数据交换标准的异构CAx和产品数据管理系统间的动态集成是网络化制造亟待解决的问题。分析了Web服务访问的产品模型数据交换标准数据的必要性和可能性,利用统一建模语言间接构建了产品模型数据交换标准和统一建模语言图解之间的映射关系。提出了基于产品模型数据交换标准的开放式产品数据管理网络服务架构,并将其应用于CAx和产品数据管理系统的集成方案。分析了架构的内部结构及功能模块,以计算机辅助设计系统为例,阐述了其利用简单对象访问协议消息调用公共产品数据管理网络方法的信息流程。基于产品数据交换标准和面向服务架构的方法,开发了接口功能模块,为系统集成的实施奠定了基础。     

基于STEP和STEP-NC的CAD/CAPP/CAM/CNC系统集成技术研究

针对当前CAx系统间难以实现产品信息交换和共享的问题,提出了一种基于产品模型数据交换标准和数据接口标准的信息集成方法;建立了一个计算机辅助设计／计算机辅助制造／计算机数字控制系统集成模型,采用产品模型数据交换标准和数据接口标准中性文件形式描述产品信息,各系统之间通过中性文件实现信息的交换和共享;深入研究了工艺信息建模、STEP AP203文件到AP224文件的转换及自动特征识别等关键集成技术。