A sensor-driven approach to Web-based machining

The objective of this research is to develop a framework named Wise-ShopFloor and the enabling technologies for collaborative manufacturing in a decentralized environment. Particularly, this paper presents our latest development on Web-based and sensor-driven remote machining. Once a product design is given, its process plan and NC codes are generated by using a distributed process planning (DPP) system. The NC codes are then used for remote machining via a standard Web browser and a Java GUI interface running inside the browser. In this paper, the focus is given to the concept, architecture and a prototype implementation of the enabling technology. A case study of a test part machining on a 5-axis milling machine is also completed for testing and validation. It is expected that the developed technology can be applied to design verification via remote machining as well as real part production in a distributed manufacturing environment.     

一种基于Web的汉英CAPP应用研究及开发

经济全球化要求CAPP支持远程设计和产品数据共享,而传统的CAPP系统只支持本地设计,生成的工艺文件也是单一语言的,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WEB的中英文工艺设计和计算机辅助翻译软件提出需求。本文在分析国内外计算机辅助翻译(computer aided translation , CAT)的现状和工艺语言特点的基础上,对中英文工艺编制和机助翻译系统的总体结构、功能及关键技术的实现方法做了一些探索,提出了一种基于WEB的汉英CAPP系统。在此基础上,针对某航空企业的特点开发了一套工艺编制与计算机辅助翻译软件,并取得很好的使用效果。     

A constraint-based operation sequencing for a knowledge-based process planning

Process planning is a decision-making process. Decisions on machining operations for a particular feature have to be made on various independent conditions such as which operation should be performed with which tools and under what cutting parameters. An integrated knowledge-based CAPP system called ProPlanner has been developed. The system has five modules namely information acquisition, feature recognition, machining operation planning and tool selection, set-up planning, and operation sequencing. Most process-planning systems do not produce alternative process plans. Usually, a fixed sequence created by a process plan is not necessarily the best possible sequence. Therefore, the aim should be to generate all possible operation sequences and use some optimality criteria to obtain the best sequence for the given operating environment. This paper presents an efficient heuristic algorithm, belongs to the system's operation sequencing module, for finding near-optimal operation sequences from all available process plans in a machining set-up. The costs of the various machining schemes are calculated and the machining scheme with the lowest cost is chosen. All feasible cutting tools are identified for each particular feature and the corresponding machining operations. This process is repeated for all the features in the machining set-up. All possible feature sequence combinations allowed by the current feature constraints are then generated. Appropriate cutting tools are identified and assigned to different operations. The feature sequence with the smallest number of tool changes is adopted.     

An integrated web-based CAD/CAPP/CAM system for the remote design and manufacture of feature-based cylindrical parts

This work describes the implementation of an integrated web-based CAD/CAPP/CAM system for the remote design and manufacture of feature-based cylindrical parts. This system, called WebMachining (), was developed in an e-manufacturing context, and the use of features allows the integration among the activities of collaborative design (WebCADbyFeatures), generative process planning (WebCAPP) and manufacturing (WebTurning). Through the WebCADby Features agent-based collaborative design module, cylindrical parts are modeled based on the synthesis of design features, in a Concurrent Engineering context. The WebCAPP generative CAPP module maps design features into machining features (including turning, milling, and drilling), and the mapping considers the setup, geometry, and operation. It uses a data structure similar to STEP-NC, and the generated process plans are nonlinear (i.e. they have alternatives). The WebTurning module performs the remote manufacture of the part, and it is based on a client–server architecture, where: (a) the servers are represented by the programs located at a workstation (Linux platform), which are connected to the machine tool through an Ethernet network interface; (b) the client is represented by a Java Applet. Some examples are provided in this paper, illustrating the remote design, process planning and manufacture of parts in a CNC turning center.     

Integrated Structural–Architectural Design for Interactive Planning

Traditionally, building floor plans are designed by architects with their usability, functionality and architectural aesthetics in mind; however, the structural properties of the distribution of load‐bearing walls and columns are usually not taken into account at this stage. In this paper, we propose a novel approach for the design of architectural floor plans by integrating structural layout analysis directly into the planning process. In order to achieve this, we introduce a planning tool which interactively enforces checks for structural stability of the current design, and which on demand proposes how to stabilize it if necessary. Technically, our solution contains an interactive architectural modelling framework as well as a constrained optimization module where both are based on respective architectural rules. Using our tool, an architect can predict already in a very early planning stage whose designs are structurally sound such that later changes due to stability reasons can be prevented. We compare manually computed solutions with optimal results of our proposed automated design process in order to show how much our proposed system can help architects to improve the process of laying out structural models optimally.     

A knowledge-based process planning system for injection mold

The goal of this study is to develop a knowledge-based process planning system interfaced with design for injection mold. Mold parts are interactively designed by using feature-based design approach, and then a part feature database is created through a data conversion module. Attribute information of the database is used as an input for the expert process design module and the standard time estimation module of the knowledge-based process planning system developed in this study. In this developed system, decision making of process design is performed by rules which were acquired from experienced process planners through interviews, and machining operation time is estimated by using empirical formulas derived from the actual shop floor data. A case example of split cavity plate is used to demonstrate the system performance.     

Manufacturing planning and predictive process model integration using software agents

Intelligent agents provide a means to integrate various manufacturing software applications. The agents are typically executed in a computer-based collaborative environment, referred to as a multi-agent system. The National Institute of Standards and Technology (NIST) has developed a prototype multi-agent system supporting the integration of manufacturing planning, predictive machining models, and manufacturing control. The agents within this platform have access to a knowledge base, a manufacturing resource database, a numerical control programming system, a mathematical equation solving system, and a computer-aided design system. Intelligence has been implemented within the agents in rules that are used for process planning, service selection, and job execution. The primary purposes for developing such a platform are to support the integration of predictive models, process planning, and shop floor machining activities and to demonstrate an integration framework to enable the use of machining process knowledge with higher-level manufacturing applications.     

基于Solr的分布式全文检索系统的研究与实现

随着当前网络信息资源的急剧膨胀,传统的检索系统已经难以在处理海量数据时提供高效的、可靠的服务。针对该情况,设计并实现一个基于Solr的分布式全文检索系统。系统通过网络爬虫抓取网页信息,将抓取的信息储存为文本文件;然后利用Solr索引处理模块,在多台计算机节点上并行创建索引,有效地提高系统建立索引的速度;系统通过Zoo-keeper管理集群,将搜索模块设计为分布式,有效地提高检索性能;最后设计了友好的用户界面。目前,系统可以在百万数据量的环境下稳定运行,具有较强的实用价值。     

Geometric reasoning for mill-turn machining process planning

An integrated system to support both product and manufacturing process design should be such that (1) the part design can be evaluated and redesigned based on manufacturability analysis and (2) the manufacturing processes can be selected efficiently and flexibly exploiting product information provided by part design representations.

In this paper, we describe the feature-based geometric reasoning system for part modeling and process planning as applied to mill-turn machined parts. The feature recognition system based on convex decomposition and the mapping method to relate the negative feature volumes to machining process classes are applied to mill-turn parts. Also, the geometry-based machining precedence relations have been generated for various alternative machining feature decompositions. The above geometric information is input to mill-turn machining process planning to determine machining process sequences and assignment to multiple spindles and turrets.     

IKOOPPS: an intelligent knowledge-based object-oriented process planning system for the manufacture of progressive dies

Abstract: This article describes an intelligent knowledge-based object-oriented process planning (IKOOPP) system for the manufacture of progressive die plates. A die assembly is designed using a variety of standardised components based on a computer-aided design (CAD) system. A feature recognition module extracts all the pertinent geometrical properties and functional attributes of each machining feature from the CAD representation models. These properties and attributes are converted into an object-oriented representation. Knowledge of the functions of the machining feature allows process planning information to be automatically deduced. Specialised tool engineering knowledge are formulated as production rules or procedures to establish the required set of cutting tools, together with the machining allowances and sequence of operations.     

Structured intelligence for self-organizing manufacturing systems

This paper deals with fuzzy scheduling and path planning problems by genetic algorithms. We have proposed a self-organizing manufacturing system (SOMS) that is composed of a number of autonomous modules. Each module decides output through interaction with other modules, but the module does not share complete information concerning other modules in the SOMS. Therefore, we require structured intelligence as a whole system. In this paper, we consider a manufacturing line composed of machining centres and conveyor units. The manufacturing procedure can be divided into a sequence of three modules: (a) tool locating module, (b) scheduling module, and (c) path planning module. The tool locating problems have been already solved. In this paper, we first solve the scheduling problem as global preplanning. Here we assume that the processing time is not constant, because some delay may occur in the machining centres. We therefore apply fuzzy theory to represent incomplete information abou t the machining time. We solve the fuzzy scheduling problem with a genetic algorithm. After global preplanning, the path planning module transports materials and products. Next, the scheduling module acquires the actual processing time of each machining centre. Based on the processing time, the schedule module generates a fuzzy number for the processing time. We discuss the effectiveness of the proposed method through the computer simulation results.     

Operation sequencing in an automated process planning system

One of the most difficult tasks we face in automated process planning is determination of operation sequencing. In this paper we present an approach to automatic generation of machining sequences in an object-oriented automated process planning system. Sequencing of machining operations is carried out in three phases of planning: initial planning, set-up planning, and final planning. The initial planning generates general plans including the required operations and machine cells. Two types of information are used at this stage, manufacturing process knowledge and component information, including features and associated dimensions, tolerances, surface finish, and material conditions. Based on process requirements decided in the initial planning, the set-up planning selects machines and fixtures, decides the clamping surfaces and feature accessibility, and sequences the set-ups. The final planning determines all the detailed sequences of operations based on the set-ups using the built-in manufacturing logic and heuristics. We introduce the set-up planning, the core of the planning system, to link the part model, initial planning and final detailed planning. The strategy has been implemented in an object-oriented process planning system. An example is provided to demonstrate the approach.     

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.     

Generation of alternative process plans in integrated manufacturing systems

The availability of alternative process plans is a key factor for integration of design, process planning, and scheduling functions. The availability of alternative process plans can speed up the process of incremental process plan generation which can help in providing real time cost feed back to the designer after each design modification. Also alternative process plans relax the constraints in the optimization of production schedules, which in turn results in more efficient use of production resources and better delivery schedules. This paper describes a methodology for generation of alternative process plans in the integrated manufacturing environment. The procedure consists of: selection of alternative machining processes, clustering and sequencing of machining processes, and generation of a process plan network. Each of these steps is explained in detail. The result of the procedure is the process plan network that provides all alternative process plans for the given part. Methods for the selection of an optimal process plan are also described. Computational complexity of the procedure is discussed and experimental results on several realistic examples are shown.     

An integrated intelligent machining system for axisymmetric parts using PC-based CAD and CAM software packages

Machining process planning involves the formation of a set of directions describing the machining operations required to transform raw stock into a finished part. Conventional process planning, performed manually, relies on the knowledge and competence of an experienced process planner and tends to be time consuming and error prone. In the past two decades, much effort has been spent on improving process planning by utilizing the power of a computer to emulate the capabilities of an experienced planner. During the same period, computer-aided design (CAD) and computer-aided manufacturing (CAM) software has been developed to enhance design productivity and to assist the NC code generation facets of the machining process. The entire planning process may be automated be integrating CAD and CAM using computer-aided process planing (CAPP). The research described in this paper outlines the design and development of an intelligent CAPP system integrating two commercial CAD and CAM software packages, Autocad and Mastercam.     

Fuzzy-set-based approach for concurrent constraint set-up planning

Material removal processes are integral parts of many manufacturing systems. They are either primary machining processes or an important part of preparing toolings for subsequent forming and moulding processes. Manufacturing process planning identifies the type of material removal processes and the machining parameters, cutting tools and fixtures needed to generate the features on a part. Previous research in manufacturing process planning has concentrated mainly on the role of features, in the derivation of the associated process and fixture plans. Many computer-aided process planning (CAPP) and computer-aided fixture planning (CAFP) systems derive process and fixture plans from the features on a part, on the basis that these features are context-free. However, manufacturing operations are interdependent processes. In the author's computer-aided set-up planning (CASP) system, a different perspective is adopted. Feature relations form the core of the conceptual structure. These features relations, which are often imprecise, are used in deriving set-up plans. The feature relations, which may be due to geometrical constraints, tolerance requirements, etc., are modelled using fuzzy sets and fuzzy relations. This paper presents the various feature relations considered in the present system and proposes a practical planning algorithm for set-up planning.     

OOPPS: an object-oriented process planning system

This paper presents an object-oriented approach to the development of a generative process planning system—Object-Oriented Process Planning Systems (OOPPS). The system consists of three functional modules: object-oriented product model (OOPM) module, object-oriented manufacturing facility model (OOMFM) module, and object-oriented process planner (OOPP). The OOPM has a hierarchical structure with six classes of objects, class Products, class SubAssembly, class Part, class CSGTree, class Solid and class Feature. It can represent a product with all detailed information. The OOMFM is used to represent a cellular manufacturing system including machine cells, machine tools fixtures, and cutting tools. The OOPP generates process plans for parts using a multi-level hierarchical planning approach with four levels: cell-level planning, machine-level planning, fixture-level planning and tool-level planning. At the cell-level, all required operations are determined based on the feature specifications. Machine cells are then selected, based on the selected operations, for the minimal inter-cell movement. The machine-level planning selects the machines within the chosen cells. The fixtures are also selected on the selected machines. At the fixture-level planning, part setups and their sequences are selected. Finally, the tool-level planning determines all details for the process plans. An automated progamming system was also developed to link the OOPP to Smart CAM to generate CNC programs. An example has been used to illustrate the approach.     

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.