Process planning and machining sequence

Most Computer Assisted Process Planning [CAPP] is of either the variant or generative type. The variant type makes use of the existing process plans in developing process plans for new parts based on the geometric similarities. The generative type process planning develops process plans from scratch based on geometric features to be generated in machining. Several software packages are available for developing process plans for cylindrical parts and prismatic parts. Studies on the application of Artificial Intelligence [AI] techniques in developing Expert Systems to prepare process plans are emerging. It is important to have a basis for determining the machining operation sequence in process planning. This paper outlines a method of determining the machining operation sequence in process planning using the principles of graph theory considering factors such as dimensional and geometrical tolerances, surface finish, accuracy and cost.     

e-CAPP: A distributed collaborative system for internet-based process planning

Advances in distributed technologies have enabled engineers to communicate more effectively, collaborate, obtain, and exchange a wide range of design resources during product development. Shared internet-based virtual environments allow experts in remote locations to analyze a virtual prototype, together and simultaneously in centers in which the product is being developed.This paper presents a system for distributed and collaborative environment which could assist manufacturing enterprises and experts in discussing, suggesting, evaluating and selecting best process plans for family of manufacturing parts. The represented e-CAPP system enables the implementation of expert knowledge in an appropriate knowledge repository. The knowledge from this repository is integrated into intra-company CAPP systems and used while generating process plans for new products. The proposed internet-based collaborative environment, dedicated to distributed process planning, is yet another step in the direction advancing of distributed manufacturing.     

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.     

Automated feature ordering for generative process planning systems

Abstract: Generative computer aided process planning (CAPP) systems are typically split into two main modules. The first is concerned with the identification of component features and their parameters, while the second addresses the problem of automatically ordering the manufacture of the features into an efficient process plan. BEPPS is a CAPP system under preparation at the University of Bath. It has been designed with a modular structure that includes modules for conventional machines, NC machines, tooling and fixtures, cost estimating and links to both CAD and Production Management Systems. This paper concentrates on the BEPPS-ROT module for planning rotational components on conventional machine tools, and in particular on the methodology adopted for feature ordering. The novel feature ordering logic is based on rules gathered from industry and takes into account the constraints imposed by such features as the work holding arrangements and the need to rechuck the component during manufacture. After the feature identification stage has been completed the feature ordering logic enables machine tools and equipment to be selected and the process plan to be generated automatically.     

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     

网络制造环境下CAPP系统关键技术研究

分析了网络制造环境中CAPP系统具有的新特点,提出了基于B/S结构的CAPP系统框架,并深入探讨了实现网络制造的CAPP系统的一些关键技术,如系统功能模块的实现方法、远程协同工艺设计技术、基于XML的信息集成技术、合作伙伴的评估与选择策略等。     

An Internet-based intelligent design system for injection moulds

The rapid growth of Internet and information technologies in recent years provides a solution to support and facilitate collaborative product developments among different geographically distributed enterprises. An effective and feasible tool to aid the collaborative development of injection moulds can be realized by developing an Internet-based mould design system as one of the modules of a collaborative product development system. This paper presents a prototype Internet-based intelligent design system for injection moulds. The architecture of the system consists of an interactive KB mould design system embedded in an Internet environment. A Java-enabled solution together with artificial intelligence techniques is employed to develop such a networked interactive CAD system. In this system, the computational module, the knowledge base module and the graphic module for generating mould features are integrated within an interactive CAD-based framework. The knowledge base of the system would be accessed by mould designers through interactive programs so that their own intelligence and experience could also be incorporated with the total mould design. The approach adopted both speeds up the design process and facilitates design standardization which in turn increases the speed of mould manufacture. A practical case study is presented to illustrate the operations of the Internet-based mould design system.     

Design and manufacturing of sheet-metal parts: Using features to aid process planning and resolve manufacturability problems

This paper describes an integrated system for the design and production of sheet-metal parts. We have identified some important features for the sheet-metal bending process. These features are automatically generated as the design progresses. After the designs are complete, our automatic process planning system uses the features and generates new ones to aid the production of plans with near-minimum manufacturing costs. Finally, these plans are used to produce parts on an automatic bending system.Once a plan is generated, it can be used to manufacture the part, and to provide feedback to design and other factory systems. The application of features and the potential feature interaction problems are discussed. Several key manufacturing problems are also considered and the result of planning is used to resolve these problems. By solving these feature interaction problems and often practical manufacturing issues, we are able to plan and manufacture the majority of the parts we have tested less than one hour after the flat patterns are prepared.     

参数化CAD-CAPP系统技术的研究与应用

针对现代制造企业对信息集成的需求,研究了参数化CAD/CAPP系统的原理及相关技术.利用相似性原理、可重用性原理、实例推理技术、设计知识库技术、参数化技术开发了参数化CAD模块.开发了基于设计知识数据驱动、工艺知识约束修改典型工艺模板的派生式参数化CAPP模块.并建立了巷道式双立柱堆垛机参数化CAD/CAPP系统,实现...     

An integrated fixture planning and analysis system for machining processes

Fixture planning is an important part of computer-aided process planning (CAPP), which is the link between design and manufacturing in a CIM environment. This paper presents a rational approach to computer-assisted fixture planning (CAFP), emphasizing integration of fixture planning with process planning, an issue that has not been adequately addressed until very recently. A systematic approach to fixture selection is outlined for planning of modular fixtures. A prototype CAPP-CAFP system has been developed at UCLA and linked to a commercial CAD system, namely, CADAM. Part design information can be extracted from the CAD model and multiple-view engineering drawings of a part stored in the CADAM system. Modular fixture elements can be selected automatically by the CAPP-CAFP system and the generated fixture layout can be displayed on the screen. Included also in the system is a fixture analysis module for verification and rationalization of a fixturing scheme. The force analysis module has a built-in local optimization routine that can determine the clamping forces of more reasonable magnitudes. The friction forces between the fixture and the workpiece can also be considered for simple cases.     

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。     

Case-based process planning using an object-oriented model representation

This research focuses on the development of a process-planning system. This system utilizes case-based techniques for process selection and sequencing to combine the advantages of the variant and generative approaches to process planning. The case-based process planner utilizes an object-oriented model representation to operate on general three-dimensional prismatic parts, which are represented by a collection of features (e.g. slots, pockets, holes, etc.). Each feature subplan is developed by the case-based planner. Then the feature subplans are combined into the global process plan for the part via a hierarchical plan-merging mechanism. Abstracted feature subplans correspond to cases, which are used in subsequent planning operations to solve new problems. The abstracting and storing of feature subplans as cases is the primary mechanism by which the planner learns from its previous experiences to become more effective and efficient.     

基于Web服务的协同制造研究

产品的复杂性决定了产品制造过程的复杂性,需要设计、工艺,生产等部门在各个环节以及不同制造原料和生产人员协同完成,网络以及网络化制造的发展为分布式协同制造提供了实现环境,Web Services技术的成熟化为实现协同制造提供了技术支持,各个系统通过Web Services以及可扩展标记语言实现异构信息的共享及制造过程协同.研究了基于Web Ser-vices的协同制造,提出了面向服务的协同制造管理框架,并分析了框架的实现.最后将协同制造管理框架应用到车间管理信息系统,并使CAD,PDM、CAPP、设备、人事、生产信息等协同到制造过程,实现制造过程集成管理.     

Feature-based generation of machining process plans for optimised parts manufacture

Efficacious integration of such CAx technologies as CAD, CAM and CAPP still remains a problem in engineering practice which constantly attracts research attention. Design by feature model is assumed as a main factor in the integration effort in various engineering and manufacturing domains. It refers principally to feature clustering and consequently operation sequencing in elaborated process plan designs. The focus of this paper is on CAPP for parts manufacture in systems of definite processing capabilities, involving multi-axis machining centres. A methodical approach is proposed to optimally solve for process planning problems, which consists in the identification of process alternatives and sequencing adequate working steps. The approach involves the use of the branch and bound concept from the field of artificial intelligence. A conceptual scheme for generation of alternative process plans in the form of a network is developed. It is based on part design data modelling in terms of machining features. A relevant algorithm is proposed for creating such a network and searching for the optimal process plan solution from the viewpoint of its operational performance, under formulated process constraints. The feasibility of the approach and the algorithm are illustrated by a numerical case with regard to a real application and diverse machine tools with relevant tooling. Generated process alternatives for complex machining with given systems, are studied using models programmed in the environment of Matlab^® software.     

Modeling integrated CAPP/PPS systems

In order to solve the isolation and the unilateral sequence integration between CAPP and PPS, this paper proposes the integrated system of CAPP and PPS based on distributed and dynamic process planning (ICAPPS), aiming for single-piece, small-lot and made-to-order production (SPSLMOP), and then systematically builds the integrated ICAPPS model. On the basis of the integrated model, this paper constructs the function model of ICAPPS, which includes the designing layer, the part planning layer, the shop planning layer and the scheduling layer in detail, according to the requirement for the rationalization of resource utilization, process design and plan scheduling in SPSLMOP.     

Computer-aided process planning—State of the art and future development

Computer-aided process planning (CAPP) is regarded as the critical link between design and manufacturing. Particularly in the integration of computer-aided manufacturing, process planning plays an outstanding role in the integrated flow of information.This paper gives a broad view of today's situation in computer-aided process planning in a real industrial environment. Characteristics for the classification of CAPP systems are derived and the main trends in the future development of CAPP software are pointed out. Feature-based modelling of manufacturing processes as the basis for integration-oriented software development is briefly described.     

Three tiered web-based manufacturing system—Part 1: System development

This paper provides a demonstration of harnessing the power of the Internet to enable collaborative manufacturing in such a setup where the key components such as the human resource personnel and the manufacturing equipment are geographically separated. As part of the framework a platform independent and cost-effective means of remotely operating a 3-axis computer numerical control (CNC) drilling machine securely via the Internet has been developed. In addition, an infrastructure to allow remote manufacturers to collaborate on a product design as well to monitor the drilling process in real time is presented. The framework rests on sound security foundation implemented using technologies such as firewall, authentication modules and transport layer security (TLS) protocol to promote safe usage of the drilling machine. It is worth mentioning that the architectural design is generic and modular in nature and as such, any other genre of CNC machine such as milling and turning could be substituted in place of drilling with only machine-specific changes to the existing system.     

基于神经索引实例与知识推理的混合型智能CAPP策略

提出了一种新的基于耦合神经网络实例与知识的混合推理策略,采用面向对象的方法表达实例和知识,将神经索引模型引入实例推理中,在此基础上实现了ＣＡＰＰ的变异设计。同时,建立了基于零件及其工艺数据知识的分层知识表达与层次式推理机制,从而实现了ＣＡＰＰ的创成式设计。在给出这种知识化的ＣＡＰＰ系统的总体结构之后,详细讨论了基于神经网络的实例索引模型及实例推理和知识基推理的实现过程,由于吸收了派生法的类比设计思