Development of a CAD-based intelligent manufacturing system

This research proposes a CAD-based manufacturing system that embraces computer-aided design, design for manufacturing and assembly (DFMA), computer-aided process planning (CAPP), computer-aided assembly planning (CAAP), and vision-robot integration. The proposed system starts with the design of products using a commercial CAD software, Autocad. The design data is then extracted from the CAD database and organized into a standardized product model. Interface programs are used to translate the geometrical and topological information in the model into DFMA, CAPP, CAAP and vision image representations. Based on the results generated by the interface programs the applications using artificial intelligence techniques can automatically generate redesign advises, CNC part programs, assembly sequence and instructions for robots.     

基于特征设计的CAD系统

介绍基于Ｐｒｏ／ＥｎｇｉｎｅｅｒＣＡＤ系统，借助于Ｐｒｏ／Ｄｅｖｅｌｏｐ开展工具二次开发的基于特征设计的ＣＡＤ系统，该系统操作简单方便设计效率高，可方便地对特征增加附加信息，为后续过程提供了丰富的信息，便于ＣＡＤ与后续过程的信息集成和功能集成，提出广义特征概念，为基于广义特征建立产品集约信息模型打下了良好的基础。     

基于STEP的特征模型及重构算法

随着CAX技术的发展,特征技术得到越来越多的重视,特征技术的使用,大幅度提高了产品的设计、制造、集成等过程的效率。目前,基于特征的CAD、CAM系统是市场的主流,CAPP是完全基于特征的应用系统。但是在STEP的众多应用协议中,涉及机械设计、制造、管理的应用协议有很多,但是这些应用协议基本上没有提供对特征的支持。AP224是较早支持特征的STEP应用协议,主     

基于STEP的三维CAD和PDM系统集成方法研究

研究了基于STEP标准的产品信息模型、CAD数据交换接口、产品数据交换接口,提出了基于STEP中性机制和产品信息模型的三维CAD和PDM系统集成框架,该框架有助于实现广义CAD功能CAD/CAE/CAPP/CAM/CAQ/PDM/ERP之间的系统集成,异地、异构系统在企业间的集成,能够为企业设计和管理信息化提供一体化解决方案.     

An approach to identify design and manufacturing features from a data exchanged part model

Due to the large variety of CAD systems in the market, data exchange between different CAD systems is indispensable. Currently, data exchange standards such as STEP and IGES, etc. provide a unique approach for interfacing among different CAD platforms. Once the feature-based CAD model created in one CAD system is input into another via data exchange standards, many of the original features and the feature-related information may not exist any longer. The identification of the design features and their further decomposition into machining features for the downstream activities from a data exchanged part model is a bottleneck in integrated product and process design and development. In this paper, the feature panorama is succinctly articulated from the viewpoint of product design and manufacturing. To facilitate feature identification and extraction, a multiple-level feature taxonomy and hierarchy is proposed based on the characteristics of part geometry and topology entities. The relationships between the features and their geometric entities are established. A litany of algorithms for the identification of design and machining features are proposed. Besides, how to recognize the intersecting features or compound features based on the featureless chunks of geometry entities is critical and the issue is addressed in the paper. A multi-level compound feature representation and recognition approach are presented. Finally, case studies are used to illustrate the validity of the approach and algorithms proposed for the identification of the features from CAD part models in neutral format.     

A PDES/STEP-based model and system for concurrent integrated design and assembly planning

Product data exchange and interfacing between different CAD/CAM systems are of great importance to the development of concurrent integrated design environments and computer integrated manufacturing systems. This paper presents a STEP-based method and system for concurrent integrated design and assembly planning. An integrated object model for mechanical systems and assemblies is first defined by a hierarchy of structure, geometry and feature. The structure is represented as a component-connector or joint multi-level graph with both hierarchical functional and assembly relations. These hierarchical relation models are then used for uniformly describing their causal relations both for assembly level and feature based single part level. The generic product assembly model is organized according to STEP, using mostly the entities of integrated resources and partly self-defined entities, which are necessary for design and assembly planning. Based on the generic product assembly model, STEP-based strategies and agent concepts are used for agent-based concurrent integration of design and assembly planning. A prototype system, consisting of a CAD system, a product modeling system, an assembly planning system, and an assembly evaluation system is developed, in which product data can be exchanged between these subsystems. Details about the implementation of the system are addressed. The integrated design and assembly planning system can support the introduction of a new product. The results of assembly planning are feedback to the stage of assembly design to improve on the design. A case study is carried out for assembly-oriented design of a gearbox, to illustrate the proposed approach and to validate the developed system.     

提高蒸气流量计量精度的算法及实现

为了充分利用气体流量测控网络资源，分析了一般带温度压力补偿的节流式流量计量算法在ｔ，ｐ波动较大时，不能很好地补偿气体密度的问题。提出了利用网络上层监测站进行数据查询和复杂计算，向下传输最新补偿参数的方法，去提高算法精度，给出了算法流程图，对算法进行了仿真，其效果令人满意。     

面向并行工程的集成产品信息建模技术研究

针对并行工程的需求提出广义特征概念，基于广义特征和参考ＳＴＥＰ标准，建立了面向并行 集成产品信息模型，借助所建立的集成产品信息模型实现ＣＡＤ／ＣＡＰＰ／ＣＡＭ的信息集成，从而为实现产品并行开发过程的信息集成和功有集成打下了良好的基础。     

An integration of feature recognition and process planning functions for turning operation

This paper deals with the development of a Computer Aided Process Planning(CAPP) system interfaced with CAD for turning operation. The developed system performs CAD interfaced feature recognition from part geometry database, and the decision procedures for process planning functions such as process and operation selection, machine tool selection, setup planning and operation planning.

The system runs under personal computer environments and AutoCAD is employed as CAD system and Turbo-C is used for the decision procedures. A case study is performed to evaluate the performance of the system.     

An integrated CAPP/CAM system for stamping die pattern machining

Since the early 1980s, CAPP has been expected to bridge the gap between CAD and CAM. Though numerous research works on CAPP have been reported, it is not easy to find a commercial CAPP system applicable to complicated objects with freeform shapes such as mold and die. The dependency on CAM system is holding one leg of CAPP, while the complexity of the solution space in freeform shape machining has a tight grip on the other. This paper exemplifies that these obstacles on the CAPP bridge can be overcome by the integration with CAM and by focusing on a specific application area. Major components of a staming die for the car body panel are manufactured by machining the raw stock castings, which are usually made by the lost foam casting process. Die pattern is the lost foam pattern made of Styrofoam for the raw stock casting. The industry trend is to build die patterns by CNC machining. In this paper, a highly specialized CAPP/CAM integrated system, called Generative Pattern Machining (GPM), for automatic tool paths generation to cut die pattern from the CAD model of the stamping die is described. The overall structure and the detailed steps of GPM are explained. GPM is being used by DaimlerChrysler pattern shop very successfully.     

并行工程在汽车车身开发与制造上的应用

本文分析了常规车身ＣＡＤ／ＣＡＭ技术所存在的弊病,提出了采用并行工程的原理进行车身开发及车身工装设计与制造的方法。重点介绍了实施车身并行工程要解决的关键性技术,诸如建立集成化的产品数据模型、ＣＡＤ／ＣＡＰＰ／ＣＡＭ集成技术、建立多功能小组、计算机技术支持等。     

CAD/CAPP集成的关键技术

该文提出了基于特征实体模型上的截面轮廓造型自动特征识别方法。这种方法探索了一条实现自动特征识别的新途径。还提出了基于特征名、形面名的多层次多方位的零件信息描述方法。实现了对复杂箱体类零件的加工特征自动识别与信息自动提取,从而实现了CAD/CAPP系统的信息自动传递。     

CATC — A Computer Aided Tolerance Control system

Computer utilization in manufacturing systems is increasing at a rapid rate. Developments thus far have been disjointed. Much work needs to be done in the area of integrating computer aided design and computer aided manufacturing (CAD/CAM). Tolerance control is an important component in the integration of CAD and CAM. Selection of design tolerances affects the build-ability of a product. The selection of manufacturing processes and sequence of processes affects process tolerance stacking. Unexamined process tolerance stacking leads to scrap and rework. A computer aided tolerance control (CATC) system is presented in this paper. This system is based on the tolerance chart technique. The CATC system is interactive and uses computer graphics for information display. The system can be used for computer aided process planning (CAPP) and for CAD/CAM integration.     

以OOEDB为核心的集成化CAD/CAPP/CAM 系统GS-ICCC的设计与实现

ＧＳ－ＩＣＣＣ是一个以自行研制开发的面向对象工程数据库管理系统ＯＳＣＡＲ为核心的集成化ＣＡＤ／ＣＡＰＰ／ＣＡＭ系统，它的主要特点是按照ＳＴＥＰ标准在全局产品数据模型基础上实现ＣＡＤ，ＣＡＰＰ，ＣＡＭ的信息集成，本文围绕着这一原则介绍了ＧＳ－ＩＣＣＣ的系统总体结构，ＯＳＣＡＲ功能组织，全局产品数据建模框架以系统集成的设计与实现。     

基于STEP和约束机制的CAD/CAP集成技术的研究

提出一种支持用户自定义ＣＡＰＰ数据结构,及与多种ＣＡＰＰ系统集成的方法,通过对ＣＡＰＰ系统的数据模型（用Ｃ／Ｃ＋＋描述）进行分析,获取其词法与语义信息,按照ＣＡＰＰ系统数据模型的数据要求,在集成系统的末端给出工艺数据,以工艺特征树为操作核心,实现了ＣＡＤ系统与多种ＣＡＰＰ系统之间的数据交换。同时,该技术在产品数据的交换中支持ＳＴＥＰ标准,实现了基于ＳＴＥＰ的信息集成。     

面向集成的CAD系统

在ＣＩＭＳ中，集成是关键技术。设计者在不同环境中产生的数据需要相互交换和共享。该文主要介绍设计阶段产生的数据如何与ＣＡＰＰ／ＣＡＭ集成。开发特征造型系统，建立包含零件的几何信息和加工信息的信息模型，最后输出ＳＴＥＰ中性文件，达到ＣＡＤ／ＣＡＰＰ／ＣＡＭ集成。     

面向并行设计的特征识别与模型重构方法

在分析现有CAD软件以及产品建模方法不足的基础上，引入广义工程语义特征的概念，应用广义特征对象实现面向并行设计的产品广义信息模型的简化表示；提出一种自动特征识别方法，对识别对象进行分类；以截面复杂的回转体特征为例，着重表述了基于基面的特征识别算法；扼要介绍Pro／E软件中的特征结构树，提出面向Pro／E的特征信息三级提取策略与特征信息模型重构原则，并据此开发了DFX原型系统．     

基于OpenCASCADE的“一元四体”模型实现技术研究

根据"一元四体"(简称AMFB)产品信息建模原理,应用OpenCASCADE几何造型平台研究对OpenAMFB系统进行了体系结构设计、应用框架设计。基于此并研制了以OCAF开发框架为软件架构的"一元四体"模型应用系统OpenAMFB,验证了该原理实现技术的可行性,为以模型为中心的产品信息集成系统研发提供了借鉴。OpenAMFB系统能与CAE、CAM及CAPP等系统更好地共享数据和信息,对信息、机械等工程技术领域的研究都有重要的理论参考价值和实际指导意义,对CAD/CAE/CAM/CAPP集成的发展起到一定的推动作用。