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.     

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。     

A STEP AP224 agent-based early manufacturability assessment environment using XML

Early design assessment activities have a significant impact on reducing the cost of manufacture. The efficient utilisation of the product development time and the level of coordination of the early design activities between the major stakeholders are becoming key factors for success in manufacturing today. The paper reports on a new distributed early design manufacturability assessment methodology using collaborative autonomous agents. A product data model compliant with STEP AP224 and corresponding process and facility data models are proposed to support the decision-making process. XML was used as a medium for exchange of requests and information between design, manufacturing, and facility planning agents. A prototype Web-enabled system for rapid product manufacturability assessment in the extended enterprise has been developed using distributed multi-agent CORBA objects. The reported research is a step towards the development of a generic prototype tool for collaborative design evaluation and rapid assessment of the manufacturing feasibility and resource availability at different stages of the product development process.     

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     

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。     

STEP标准在计算机辅助工程CAx中的应用

STEP是世界公认的未来产品生命周期数据交换标准,发达工业国家正大力发展制造领域的STEP标准。本文介绍了STEP标准的研究现状、接口、映射机理,重点阐述STEP应用协议组(AP)在不同CAD/CAPP/CAM/CAE/CNC及与PDM系统的数据模型和数据交换中的应用。     

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。     

A clustering-based modeling scheme of the manufacturing resources for process planning

Process planning determines how a product is to be manufactured and, therefore, is one of the key elements in the manufacturing process. The basic crux of computer-aided process planning (CAPP), however, is the diversity of manufacturing background and the complexity of process planning. Since the process plans are generated on demand with the manufacturing resources on a shop floor, modeling method of the manufacturing resources is one of most important issues in computer-aided process planning. Hence, the major objective of this research is to create a clustering-based modeling scheme of the manufacturing resources for process planning. This modeling scheme combines clustering method with averaging method so as to reasonably partition and classify the manufacturing resources on a shop floor. The proposed approach provides one of search strategies of machine tools for process planning, especially for the selection of machine tools. Finally, an illustrative example is applied to describe the clustering-based modeling scheme.     

Computer-aided process planning for NC tool path generation of complex shoe molds

This paper presents a computer aided process planning (CAPP) system for numerical control tool path generation of complex shoe molds. This CAPP system includes both the automation of auxiliary boundary curve generation and machining strategies. The automation of auxiliary boundary curve generation and machining strategies make tool path generation more accurately and efficiently. Traditional shoe mold making is a very tedious process. Even with the utilization of computer-aided design and computer-aided manufacturing (CAD/CAM), the CAM process requires long hours of tool path programming and debugging. It would also take a long time to calculate (sometimes several hours) the tool path for complex athletic footwear. In order to reduce the tool path editing and programming time, this paper proposes the use of CAPP to reduce processing time and increase efficiency. It is difficult, if not impossible, to develop a generic CAPP system that can generate a process plan to solve general production problems. However, it is quite possible to capture the domain knowledge of a certain production process and embed that knowledge into a CAPP system. We prove, by using such a system, that a very complicated process planning problem can be overcome by a knowledge-based CAPP approach. With such an approach, the traditional manufacturing process of shoe molds can be converted to an automatic manufacturing process with the CAPP system. In fact, shoe molds for real production have been created using the developed CAPP system, demonstrating the effectiveness of this approach. In this paper, we show that several complex and different shoe molds and their machining strategies were automatically planned by the proposed CAPP system. The result of a comparison between the CAPP system with the traditional approach is presented and discussed.     

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。     

Mobile database nodes for manufacturing information management: a STEP based approach

This paper describes research currently being carried out in the area of information management architectures for flexible manufacturing systems (FMS). This work originates from the idea that process control may be achieved by machines as in the standard approach but also by all the products carrying their own information. So, distribution of the information system onto each individual product requires tools and methods to manage and to provide access to product information for both automated systems and human operators. Automatic identification technologies using electronic data carriers can provide such functions and act as product information vectors. Our approach is based on the STEP technology to define computer-aided tools for data acquisition and management of product-related information implemented on mobile database nodes circulating in a CIM environment.     

Object-oriented and fuzzy-set-based approach for set-up planning

Set-up planning is not only a key element of computer-aided process planning (CAPP), but also a key factor for the integration of CAPP with computer-aided fixture planning (CAFP) and production planning and scheduling (PPS). In this work, an object-oriented and fuzzy-set-based approach is developed for set-up planning. Object-oriented technology is employed to represent set-up planning knowledge and generate alternative set-ups which can respond to the dynamic manufacturing resource and facilitate the CAPP/PPS integration. Based on fuzzy-set theory, a fuzzy evaluation function is proposed to produce optimal set-ups. Combined with a real project, a set-up planning system is developed to generate alternative and optimal set-up plans for the machining of prismatic parts.     

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。     

Extraction of manufacturing information from design-by-feature solid model through feature recognition

Feature recognition is the key to the computer-aided design (CAD) and computer-aided manufacturing (CAM) integration to build a computer-integrated manufacturing system. There are two approaches to CAD feature recognition: platform-dependent and platform-independent. In the platform-independent approach, the part’s geometrical data are extracted from a neutral file such as DXF, IGES, or STEP. In contrast, the platform-dependent approach extracts the information of the design features directly from a design-by-feature solid model through the object-oriented model of a part. This paper explains a platform-dependent approach which is implemented to translate design features into manufacturing information. This approach begins with simplification using the suppression of fillets, and clustering non-intersecting design features is done. Then, the rule-based method is employed in order to recognize machining features. Finally, the needed manufacturing information such as tool accessing direction, dimensions, material removal regions, and geometrical and topological data is recognized. The application of the proposed system would be exhibited in generating machine path code for rapid prototyping and CNC machines and providing a database for computer-aided process planning. The proposed system was implemented on Autodesk Inventor and successfully tested for many complex 3D models.     

现代CAPP技术及其发展研究

企业信息化工程推动了CAPP技术的发展和应用，本文通过CAPP的发展过程、信息技术的发展以及企业信息化工程对CAPP的需求等进行深入分析，从体系结构、系统功能、信息组织、工艺设计模式、系统性能等方面分析了现代CAPP技术的发展趋势。(1)CAPP系统的体系结构由单机模式、C／S模式向C／S模式与基于Web技术的B／S模式相结合、组件化、层次结构化方向发展；(2)CAPP系统的功能覆盖企业整个工艺领域，向集成化制造数据管理方向发展；(3)工艺设计模式向基于知识的分布协同决策的综合智能化设计技术发展；(4)CAPP的应用更加强调系统的集成性和开放性等。文中还简要介绍了相关关键技术。     

Algorithms for computer-aided generative process planning

Process planning is the function within a manufacturing facility that establishes the machining processes and parameters to be used so as to convert a piece-part from its initial form to the final form predetermined on an engineering drawing. Computer-aided process planning (CAPP) has become a major focus of manufacturing automation as it forms the interface between computer-aided design (CAD) and computer-aided manufacturing (CAM). Issues in CAPP include part representation, process selection, alternative process-plan generation, intermediate surface and tolerance determination, and operation sequencing. This paper focuses on quantitative models for determining cutting dimensions and tolerances for intermediate surfaces, and on a heuristic for sequencing cutting operations.     

A Surface Area Calculation and CAPP System for Non-Axisymmetric Deep Drawing Products

In this paper a surface area calculation for non-axisymmetric deep drawing products of elliptical shape was constructed for the design of blank shapes of deep drawing products by using an AutoLISP function in AutoCAD software. A computer-aided process planning (CAPP) system for rotationally symmetric deep drawing products has been developed. In this study, a CAPP system for non-axisymmetric deep drawing products of elliptical shape was constructed using process sequence design. The system developed consists of four modules. The first is the recognition of shape module for recognising non-axisymmetric products. The second is a 3D modelling module for calculating the surface area for non-axisymmetric products. The third is a blank design module for creating an oval-shaped blank with an identical surface area. The fourth is a process planning module based on production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by interviewing field engineers. The drawing coefficient, the punch and die radii for elliptical shape products are considered as the main design parameters. The suitability of this system was verified by applying it to a real deep drawing product. This surface area calculation and CAPP system should be very useful for reducing the lead-time for manufacturing and for improving the accuracy of products.     

基于PDM的工艺管理研究

工艺是连接产品设计与制造的桥梁，是实现产品信息集成与管理的关键。在研究工艺设计及工艺信息管理的基础上，分析了工艺管理的功能需求，建立了面向产品全生命周期集成的工艺信息模型，提出了基于PDM的两级工艺管理方案，有效地简化了CAPP系统的设计，有利于真正实现CAD、CAPP、CAM、PDM、ERP的全面集成。     

Computer aided manufacturing planning for mass customization: part 3, information modeling

To facilitate the computer-aided manufacturing planning (CAMP) for mass customization, an information model is developed for integrating the information exchange in different levels of CAMP activities. The correlative relationships between product design and manufacturing processes are established by using an object-oriented system analysis model so that the manufacturing system design can be adaptive to the change of the product design. The information model is implemented in a prototype CAMP system for part family.