Design of object-oriented database for the definition of machining operation sequences of 3D workpieces

This paper describes the activities of Object-Oriented (OO) analysis that were implemented in order to obtain a high part representation level and to give sets of structured and hierarchical data to the Computer Aided Process Planning (CAPP) system. The OO modeling activities were carried out by using the Object-Oriented System Analysis (OOSA) method which allows careful specification of all the information contained inside the system. All the models used by this method have been described in detail to show how the OO database is defined and how it can be used by a generative CAPP system. The feature model proposed is defined by taking all the part information that can be recognized and extracted from the Computer Aided Design (CAD) model into account. The result is the design of an OO database which allows the CAPP system to use manufacturing features to define machining operation sequences of 3D workpieces. The approach proposed is generic enough to integrate any geometrical forms which can be recognized and identified from the CAD system. Hole geometry is taken as an example to show the link between the step of OO analysis and the step of knowledge representation in the Expert System which has been used to generate machining cycles. The OO database presented makes up a real solution of CAD/CAPP/CAM integration by using feature modeling.     

Manufacturing Models of Biomedical Objects via CAD/CAM and GKS

Picture generating methods like tomography have drastically improved the possibility for the conception of biomedical objects in living humans. They have proved to be of major significance in surgical planning. Computer Aided Design (CAD) methods based on tomography are in the research phase for the three-dimensional reconstruction and display using computer graphics for even better visualization. We provide a method beyond that by manufacturing physical three-dimensional models via the Graphical Kernel System (GKS) and Computer Aided Manufacturing (CAM) methods. This kind of method is very well suited for visualization in some application areas. Moreover it yields physical models which can be manipulated in the preoperative phase. Lastly a physical bone model can be a substitute for the original object.     

基于CAD／CAPP并行设计的特征描述与操作

本文介绍了在作者开发的基于特征的ＣＡＤ／ＣＡＰＰ并行系统ＦＯＰＳ中,针对ＣＡＤ／ＣＡＰＰ并行设计的要求,对形状特征的表示处理策略。提出了基于加工的形状特征分类及体描述思想,并从一个新的角度认识处理形状特征,建立了基于特征描述的实体几何模型,提出了广义“凹孔”的特征认识概念及相应的“内环”处理技术,为有效地在设计过程中同时为ＣＡＰＰ系统提供必要的信息,便于进行零件设计的结构工艺性分析、评价及工艺规程     

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.     

Interfacing CAD and CAM—A study in hole design

Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) are modern tools for both the designer and manufacturing engineer. These two tools, however, are not usually integrated into one system. In this study, an effort has been made to connect design and manufacturing by interfacing them into a unified software system. Through this demonstrative CAD/CAM package, the designer interacts with a graphics terminal to enter hole design details; these, in turn, are sent to a generative automatic process planning routing which defines appropriate process plans. In addition, a cost estimate is given which provides the designer with a measure of the economic effectiveness of his design. In the future, it will be possible to interface such systems with part programming routines to obtain explicit machine control information. Such a system represents a significant step toward making totally automated manufacturing a reality.     

GMCADS系统的研究及应用

当今,机械CAD向CAD/CAM/CAE集成化方向发展,机械系统运动学/动力学分析软件是集成化CAD/CAM/CAE不可缺少的支撑软件之一。我们以多刚体系统动力学为基本理论,研制了面向问题的、交互式的通用机械计算机辅助设计系统GMCADS。本文介绍了GMCADS系统的分析原理、图形输出技术,并给出了应用实例。     

FPGA-based hardware CNC interpolator of Bezier,splines, B-splines and NURBS curves for industrial applications

Tool path interpolation is an important part of Computerized Numerical Control (CNC) systems because it is related to the machining accuracy, tool-motion smoothness and overall efficiency. The use of parametric curves to generate tool-motion trajectories on a workpiece for high accuracy machining has become a standard data format that is used for CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) and CNC systems. Splines, Bezier, B-splines, and NURBS (Non-Uniform Rational B-splines) curves are the common parametric technique used for tool path design. However, the reported works bring out the high computational load required for this type of interpolation, and then at best only one interpolation algorithm is implemented. The contribution of this paper is the development of a hardware processing unit based on Field Programmable Gate Arrays (FPGA) for industrial CNC machines, which is capable of implementing the four main interpolation techniques. It allows the selection of the required interpolation technique according the application. Two CAD models are designed for test the CNC interpolations; experimental results show the efficiency of the proposed methodology.     

STEP信息集成软件工具的设计和实现

ＳＴＥＰ是国际标准化组织ＩＳＯ正在组织开发的应用于计算机集成制造系统（ＣＩＭＳ）信息集成的产品数据表达与交换标准，ＳＴＥＰ不仅是一种规范，更是一种信息集成技术，本文以ＣＡＤ／ＣＡＰＰ／ＣＡＭ系统集成为背景，提出了ＳＴＥＰ信息集成支持工具ＥｘＴｒａ的设计和实现技术，该软件工具已成功且有效地应用于ＣＡＤ／ＣＡＰＰ／ＣＡＭ系统集成中。     

BOM在ERP升蓝软件系统中的作用

本文在分析ERP系统升蓝软件和“（CAD／CAPP）”技术特点的基础上,认为生产制造型企业在信息化建设过程中应以BOM为信息纽带,以PDM为核心,再结合CAD／CAPP和ERP升蓝软件系统,并辅以Internet和EDI系统,这将有利于实现企业信息化建设的目标。     

上海大众汽车覆盖件模具CAD/CAE/CAM系统

CAD／CAE／CAM技术在现代汽车模具设计和制造中具有重要作用。本文立足于上海大众汽车有限公司对车身覆盖件模具（CAI）／CAE／CAM系统的需求，论述了上海大众汽车覆盖件模具CAD／CAE／CAM系统的软硬件平和系统的结构体系。本文介绍的CAD／CAE／CAM系统已在上海大众的覆盖件模具设计制造和冲压工艺规划中开始应用，并取得苦于成果。     

Guest editorial

Attention has recently focused on improving the information and knowledge flow between design and manufacturing. Interfacing Computer Aided Design (CAD) with Computer Aided Manufacturing (CAM) systems has helped this information flow while also improving both processes. Once CAD and CAM systems were introduced the obvious next step to (1) decrease a product's time-to-market and its costs, while (2) increasing the product's quality, has been to utilize knowledge based system technology during both the design and the manufacturing phases of a product. Unfortunately, the knowledge based systems that we have developed have been designed as stand-alone components. These have been built using a variety of implementation philosophies, styles of reasoning and are deployed over distributed computing environments. The companies with large investments in design and manufacturing automation, as well as in expert system technology have come to realize that achieving the two goals stated above will require the integration of such diverse systems in ways that will allow their coordination and cooperation. This special issue of theJournal of Intelligent Manufacturing has brought together reports of recent research whose goal was this type of integration.     

A framework for the integration of computer-aided design and computer-aided process planning

This paper gives a procedure for integrating Computer-Aided Design (CAD) and Computer-Aided Process Planning (CAPP) systems, a key step in integrating CAD to Computer-Aided Manufacturing (CAM). The three modules required for this integration are a genetic part definition data structure, a preprocessor, and a postprocessor: all three are discussed in some detail. An evaluation of a prototype demonstration system which successfully integrated IBM's CAD package (CADAM) to the United Technologies Computer Managed Process Planning (CMPP) software is discussed.     

A framework for extending computer aided process planning to include business activities and computer aided design and manufacturing (CAD/CAM) data retrieval

Computer aided process planning (CAPP) systems have had limited success in integrating business functions and product manufacturing due to the inaccessibility and incompatibility of information residing in proprietary software. While large companies have developed or purchased complex order management and engineering applications, smaller manufacturers continue to use semi-automated and manual methods for managing information throughout the lifecycle of each new product and component. There is a need for reconfigurable and reprogrammable systems that combine advances in computer aided design (CAD/Computer Aided Manufacturing (CAM) technology and intelligent machining with product data management for documentation and cost control. The goal of this research is to demonstrate an architecture in which customer service, CAPP and a costing methodology known as activity based costing (ABC) are incorporated into a single system, thereby allowing companies to monitor and study how expenditures are incurred and which resources are being used by each job. The material presented in this paper is the result of a two year university and industry sponsored research project in which professors and students at the Costa Rica Institute of Technology developed a software application for FEMA Industrial S.A., a local machining and fabrication shop with sixty five employees and both conventional and CNC capabilities. The final results represent not only a significant contribution to local industry and to the students’ education but, also to the continuing growth of CAPP. Implementing better decision making tools and standardizing transactions in digital format would reduce the workload on critical personnel and archive valuable knowledge for analyzing company methods and expertise.     

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.     

An algorithm for CAD tolerancing integration: Generation of assembly configurations according to dimensional and geometrical tolerances

For several years, Digital Mock-Up (DMU) has been improved by the integration of many tools as Finite Element (FE) Analysis, Computer Aided Manufacturing (CAM), and Computer Aided Tolerancing (CAT) in the Computer Aided Design (CAD) model. In the geometrical model, the tolerances, which specify the requirements for the proper functioning of mechanical systems, are formally represented. The nominal modeling of the parts and assemblies does not allow the prediction of the tolerance impacts on the simulation results as the optimization of mechanical system assemblability. So, improving the CAD model to be closer to the realistic model is a necessity to verify and validate the mechanical system assemblability. This paper proposes a new approach to integrate the tolerances in CAD model by the determination of the configurations with defects of a CAD part, used in a mechanical system. The realistic parts are computed according to the dimensional and geometrical tolerances. This approach provides an assembly result closer to the real assembly of the mechanical system. The Replacement of the nominal parts by the realistic ones requires the redefinition of the initially defined assembly mating constraints. The update of the mating constraints is performed by respecting an Objective Function of the Assembly (OFA). Integrating tolerances in CAD allows the visualization and simulation of the mechanical assemblies’ behavior in their real configuration and the detection of possible interference and collision effects between parts which are undetectable in the nominal state.     

JOHN A.GREGORY AND HIS PUBLICATIONS

ＪＯＨＮＡ．ＧＲＥＧＯＲＹＡＮＤＨＩＳＰＵＢＬＩＣＡＴＩＯＮＳ￥ＱｕＲｕｉｂｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｌｉｃｓＮａｔｉｏｎａｌＵｎｉｖｅｒｓｉｔｙｏｆＳｉｎｇａｐｏｒｅ１０ＫｅｎｔＲｉｄｇｅＣｒｅｓｃｅｎｔＳｉｎｇａｐｏｒｅ．１１９...     

针对产品的CAD／CAM一体化技术

本文系统地介绍了一种基于ＣＡＤ工作站，利用Ｉ－ＤＥＡＳ软件实现的针对壳体类零件的ＣＡＤ／ＣＡＭ一体化技术。论述了利用ＰＥＡＲＬ数据库实现的从ＣＡＤ模型到ＣＡＰＰ之间信息的传输，分析了在ＣＡＤ与ＣＡＭ集成中创成式ＣＡＰＰ所起的关键作用，并介绍了利用ＧＮＣ图形辅助数控软件对加工过程的仿真以及机床文件的准备，最后系统能生成正确的数控指令。系统初步实现了ＣＡＤ／ＣＡＭ一体化。     

Expert systems for manufacturing cell simulation and design

Computer Integrated Manufacturing (CIM) is approached by means of the application of Computer Aided Design (CAD), Computer Aided Manufacturing (CAM) and other CA techniques, methods and programs/program systems. These programs are often implemented as knowledge-based, or expert systems and in this way they became typical examples of engineering application of artificial intelligence. The production task of CIM systems is solved by using flexible manufacturing systems (FMSs). FMSs built up from smaller, complex units, i.e. from flexible manufacturing cells (FMCs) have several advantages. The design and the operation of manufacturing systems need new, sophisticated methods to utilize all the embedded benefits of the sophisticated and expensive elements installed for production purposes. New methods like knowledge processing technology, cooperative problem-solving techniques, etc., offer wide possibilities to design more reasonable systems. This paper describes prototype expert systems that make use of different knowledge-based tools and techniques to design (configure, reconfigure) and simulate manufacturing cells, taking into consideration technological plans and other relevant information.     

Design of a STEP compliant system for turning operations

The changing economic climate has made global manufacturing a growing necessity over the last decade, forcing companies from East and West to collaborate beyond geographic boundaries in the design, manufacture and assembly of products. The ISO 10303 and ISO 14649 Standards (STEP and STEP-NC) have been developed to introduce interoperability into manufacturing enterprises so as to meet the challenges of responding to production on demand. This paper describes and illustrates a STEP compliant CAD/CAPP/CAM System for the manufacture of rotational parts on CNC turning centers. The information models to support the proposed system together with the data models defined in the ISO 14649 standard used to create the NC programs are also described. A structured view of a STEP compliant CAD/CAPP/CAM system framework supporting the next generation of intelligent CNC controllers for turn/mill component manufacture is provided. Finally a proposed computational environment for a STEP-NC compliant system for turning operations (SCSTO) is described. SCSTO is the experimental aspect of the research and is supported by information models that and have been constructed using a structured methodology and object-oriented methods. SCSTO was developed to generate a Part 21 file based on machining features to support the interactive generation of process plans utilizing feature extraction. A case study component has been developed to prove the concept of using the milling and turning parts of ISO 14649 to provide a turn-mill CAD/CAPP/CAM environment.     

Petri nets in dynamic process planning

A framework for combining Petri Nets with Computer Aided Process Planning (CAPP) systems is presented. The Petri Nets are used to provide realtime facility status information while the CAPP system is used to generate the revised process plans. Combining these two methodologies overcomes most of the weaknesses with the traditional CAPP systems. The result is a dynamic, realtime CAPP system.