CAPP系统中基于AHP的排序优先级研究

CAPP是CAD/CAM集成的桥梁和纽带,由于工艺决策问题约束复杂、随机性强,排序准则的确定需要根据具体的加工环境和加工对象来制定。为了便于工艺路线的自动生成,本文采用AHP(层次规划法),一种数学决策模型,进行排序优先级的确定。首先介绍了AHP模型及其构造算法,然后,以回转体零件在数控加工中心上的工步排序方案决策为例,用Visual Ba-sic编制程序,验证了基于AHP的柔性工艺优先排序决策方法的可行性。     

Studies on process plan representation in CAPP systems

Process planning establishes the methods and means of converting the raw material into a finished part. The planning function interacts with the manufacturing system through (a) the design specification, (b) manufacturing resources, and (c) the process plan. Similarly, computer aided process planning (CAPP) establishes the links with its application environment through the analogous models. Though much attention is paid to the modelling of the part and manufacturing resources, modelling of the process plan has been an ignored topic to-date. The present paper discusses the need for modelling the process plan, and proposes a framework for process plan internal representation (PPIR) for the effective integration of CAPP and CAM functions. The implementation of the proposed framework in GIFTS — a CAPP system for rotational parts — is also discussed.     

A decision logic schema of process planning using backward chaining reasoning

Decision logic of process planning is one of the most difficult issues in the research on computer-aided process planning (CAPP), and also a bottleneck hampering the process of pragmatization and commercialization of CAPP. A proper methodology for decision logic of process planning is essential for describing or specifying the various decisions associated with combinations of conditions in process planning. This paper presents a decision logic schema of process planning using backward chaining reasoning in mathematical logic to address process reasoning formalization in automated process planning, which is based on a meta-modeling paradigm of the manufacturing resources [19]. The meta-modeling paradigm combines mapping theory with the first- & second-order logic in mathematical logic to address modeling the manufacturing resources and to provide a methodology for the extraction of specific process knowledge. The meta-modeling paradigm lays the foundation for the proposed decision logic schema with specific process knowledge while the decision logic schema is the extension and application of the results from the meta-modeling paradigm. The decision logic schema provides a systematic methodology for the decision-making process and inference mechanism in process planning from the global viewpoint, which can be applied to eliminate the variability from the planners’ judgement and experience. Finally, an application example is used to illustrate the decision logic schema.     

A CAPP framework and its methodology

In this paper, a computer-aided process planning (CAPP) framework and its methodology is presented. A CAPP framework is a software structure that provides a generic, consistent operating environment for the development of real CAPP systems. Based on a framework technology, the capabilities of the CAPP framework are discussed. The methodology of the CAPP framework is divided into three parts: reference architecture, modelling methods, and implementation strategy and method. Guidance is given for the design, development and running of the CAPP framework and practical CAPP systems.     

基于分级规划的CAPP工艺决策方法研究

通过分析分级规划的基本思想、子任务分解策略和求解策略,提出基于分级规划的ＣＡＰＰ决策方法。并阐明了各求解阶段的子任务的功能及特点,建立了工艺决策求解过程框图,并详细介绍了分级规划的工艺决策推理机制。     

A Generative Computer-Aided Process Planning System for Prismatic Components

This paper deals with design and development of a generative computer-aided process planning (CAPP) system for prismatic components and named PSG-CAPP. The proposed CAPP system has been divided into three modules. The first module is concerned with feature extraction. The second and third modules deal with planning the set-up, machine selection, cutting tool selection, cutting parameter selection, and generation of process plan sheet. The whole CAPP system is developed using Visual Basic 6.0 as front end and Oracle 7.3 as back end. The SolidWorks98 plus has been used for modelling, and feature extraction has been implemented using a program written in Visual Basic 6.0. The speciality of the developed CAPP system is that it is linked with the CAD module and it extracts the majority of features automatically prior to process planning. The developed CAPP system has been tested with aerospace components. The main feature of the proposed CAPP system is its ability to handle a variety of prismatic components and generate process plans for them. A case study has been included to highlight the potential of the CAPP system. ID="A1"Correspondance and offprint requests to: Professor P. V. Mohanram, Department of Mechanical Engineering, PSG College of Technology, Peelamedu, Coimbatore 641004, India. E-mail: msadaiah@yahoo.com     

动态产品模型支持下的并行 CAPP

阐述了并行ＣＡＰＰ的原理，详细描述了本文提出的并行ＣＡＰＰ的工作过程。它以新增特征为增量，依靠动态特征模型的扩展以及工艺规划模型的状态演化过程，形成一个循序渐进的ＣＡＰＰ过程。     

Workpiece modelling for computer-aided process planning

Different concepts can be applied for representation of workpiece data for CAPP. Instead of waiting for future standards, a practical method is required, which can be used for actual workpieces or those that have been designed in the past by using already existing CAD systems. Therefore, for developing the CAPP system an approach has been chosen which consists of (1) a structure and geometry recognition of the workpiece and (2) an editor for technological data.This paper shows the main characteristics of a workpiece model which can be used for process planning. The results of an analysis of workpieces in industry give an overview of the topological relationships between geometrical elements which is an essential part of workpiece modelling for future design and planning systems. Also, a link between the workpiece model and the CAPP system is presented and briefly discussed.     

基于混合智能的电火花成型加工CAPP系统的研究

基于对电火花加工工艺的分析,构造了电火花加工CAPP系统的整体结构模型;该模型采用电极的自动分割和重组的办法实现以简单电极加工复杂型腔,从而降低加工费用;利用基于简易Petri网模型的工程规程智能决策系统实现工艺决策;采用混合智能的方法实现电规准的智能选择,并采用“优先级别－权系数法”建立多目标规划模型实现对工艺过程的优化。     

Product and manufacturing capability modelling in an integrated CAD/process planning environment

Computer-aided process planning (CAPP) is one of the key components in computer integrated manufacturing (CIM) environment. Fully automatic CAPP systems require information transfer between CAD/CAM systems to be mutual, dynamic, concurrent, automatic and efficient. The difficulty in achieving this is the management of the vast amount of heterogeneous data, knowledge and complicated inference processes encountered in developing automatic planning systems. The objective of the reported research is to develop a framework for modelling and managing engineering product and manufacturing capability information in an integrated feature-based CAD/knowledge-based process planning environment. The feature-based design system is developed with a commercial boundary representation (Brep) solid modeller with additional feature-modelling functions. The process planning system is developed using a knowledge-based system, which is fully integrated with the design system through an information mapping mechanism. Process planning decisions are made by searching for a match between the product requirements and the process capability of available manufacturing systems. This is achieved by invoking the rules coded in an inferencing mechanism (an inference engine). Both the underlying methodologies and the implementation aspects will be addressed in this paper.     

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.     

并行工程中的计算机辅助工艺过程设计

介绍了一个面向并行工程的计算机辅助工艺过程设计系统。该系统以工序决策估价函数为核心,根据车间层资源状态生成可选工艺方案,用用柔性工艺路线图表示之。系统具有实现计算机辅助工艺过程设计与生产计划及调度（PPS）功能集成的体系结构和数学模型,可为非回转体零件创成地生成适用于CIMS车间的详细工艺。     

基于产品工艺设计过程管理构架的CAPP系统

先进制造技术的发展对CAPP系统的柔性提出了更高的要求。本文结合作者在CAPP中的研究与实践，把构架设计思想应用于CAPP系统，提出了CAPP领域分析模型和产品工艺设计过程管理构架。在此基础上，以作者参与开发的上海飞机制造厂CAPP系统为实例，参照产品工艺设计过程管理构架，详细论述了该系统的五大功能，由此为CAPP的研究提供了一种新的可行的方法。     

CAPP与调度集成多代理系统的资源冲突消解

针对CAPP与调度集成系统，研究了多代理混合系统的冲突消解结构和策略。首先建立了CAPP与调度集成的多代理模型，包括合作代理和非合作代理；提出了多代理系统的冲突消解决策逻辑；按照预消解、消解、协商和仲裁的阶段协调策略，提出了一个任务资源匹配过程和多个任务资源匹配过程中的资源冲突消解策略和相应的协商协议；开发了CSIMAS系统，以验证冲突消解策略和协商协议；分别讨论了工艺规划代理和车间代理冲突消解过程作为合作代理和非合作代理的实例。     

基于多智能体机制面向资源的CAPP系统研究

为提高在车间中执行的工艺规划的柔性和适应性,提出一个基于多智能体机制面向资源的CAPP系统的框架。该系统由分布式制定工艺任务的工艺信息代理和对应车间资源的资源代理组成。面向一个工艺任务,资源代理组成多个资源代理联盟,工艺信息代理通过选择资源代理联盟进行任务分配。重点研究了工艺规划和资源分配的并行,多代理之间多级协商的资源冲突消解策略,以及面向资源的工艺决策优化等关键技术。开发了原型系统以评价系统的性能,生成的面向资源的工艺方案输入车间调度系统。     

基于交货期约束的集成工艺/计划系统

为解决单件小批订货生产方式下交货期满足问题，研究CAPP／PPS集成并行模式下加工过程决策的调度方法，提出把交货期和资源负荷作为工艺设计过程的约束，基于动态分析并行协同设计模式，在一定交货期和动态的资源负荷约束下，基于约束传播和智能回溯算法的约束推理，对构成零件每个加工表面的加工方案一次调度成功，在此基础上，通过作业计划优化调度仿真，实现工艺设计与作业计划并行协同设计，达到快速准时生产的目的。     

关于提高CAPP系统可复用性的几点思考

传统 CAPP系统开发模式面临严峻挑战。产品的多样化、企业的个性化决定了通用型 CAPP系统不可能解决系统的可复用性问题 ,问题的关键在于如何建立一套可复用的 CAPP系统开发机制。本文从方法学的角度 ,思考了提高 CAPP系统开发可复用性应该实现的三个转变 ,即零件工艺模型专用化向标准化的转变、思维模式的面向过程向面向对象的转变 ,以及软件开发模式手工作坊方式向工程化方式的转变     

CAPP在现代企业生产作业计划中的集成应用

重点介绍CAPP(计算机辅助工艺设计管理系统)及其在现代企业中的运用创新情况.通过对CAPP强大功能和机加工市场对企业工艺生产管理变革需求的分析阐述,明确了CAPP的发展趋势,CAPP进一步工具化和加强与生产作业计划的紧密结合才能发挥出CAPP在机加工行业中的综合边际功效。     

工艺规划和生产计划与控制集成过程中的资源决策

为了得到合理的工艺计划和车间生产计划调度结果，分析了计算机辅助工艺规划和生产计划与控制系统基于非线性工艺规划的并行集成原理，研究了二者集成过程中出现的资源选择问题。在资源决策过程中，首先确定加工某类零件需要的机床加工能力，然后根据车间计划系统反馈的加工资源实际情况确定车间中满足加工能力的机床，最后根据机床实时状态，计算车间每一个可用机床的优先指标。应用BP神经网络以及相关算法实现了二者集成过程中的资源决策。结果表明：利用BP神经网络以及相关算法可以有效地进行CAPP／PPC并行集成过程中的资源决策。     

基于XML的工艺文件汉英翻译研究

经济全球化要求CAPP支持远程设计和产品数据共享,传统的CAPP系统只支持本地设计,生成的工艺文件是单一语言的,通用翻译软件又不能直接被CAPP系统所使用,因此对开发基于B/S结构的工艺设计和计算机辅助翻译软件提出需求.在分析了工艺语言特点的基础上,为提高基于网络的工艺语言翻译品质,提出利用XML文档进行工艺文件的结构化信息表示和信息的传递与交换,最后对机械加工工序卡的XML结构化表示做了详细说明.