STEP-NC based high-level machining simulations integrated with CAD/CAPP/CAM

With the development of manufacturing,numerical control(NC) machining simulation has become a modern tool to obtain safe and reliable machining operations.Although some research and commercial software about NC machining simulations is available,most of them is oriented for G&M code.It is a low-level data model for computer numerical control(CNC),which has inherent drawbacks such as incomplete data and lack of accuracy.These limitations hinder the development of a real simulation system.Whereas,standard for the exchange of product data-compliant numerical control(STEP-NC) is a new and high-level data model for CNC.It provides rich information for CNC machine tools,which creates the condition for an informative and real simulation.Therefore,this paper proposes STEP-NC based high-level NC machining simulations solution integrated with computer-aided design/computeraided process planning/computer-aided manufacturing(CAD/CAPP/CAM).It turned out that the research provides a better informed simulation environment and promotes the development of modern manufacturing.     

Free-form shapes: An integrated CAD/CAM system

After describing the primary aims and the structure of the implemented CAD/CAM system, the interactive design process is presented. Particular attention is paid to those components which are of primary importance due to their direct contact with the user. A CNC option for real-time tool-path generation and some details of roughing and finishing are also presented.     

C-space based CAPP algorithm for freeform die-cavity machining

Presented in the paper is a C-space based computer automated process planning (CAPP) algorithm for freeform die-cavity machining, which is an extension of the hierarchical CAPP model proposed earlier by the authors. In order to demonstrate its validity, the proposed CAPP algorithm has been implemented and applied to actual die-cavity machining examples.     

CAD/CAM integrated system in collaborative development environment

For virtual enterprises to realize efficient operation in the 21st century, it is necessary to develop an environment that can support collaborative work of multi-disciplinary groups distributed in different places. CAD/CAM integrated system is an important subsystem in this environment. In this paper, the structure of CAD/CAM integrated system is presented, then, key technologies related to realize CAD/CAM integration are discussed in detail and finally main functions and an application case of CAD/CAM integrated system is introduced.     

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.     

Efficient feature-based process planning for sculptured pocket machining

Feature is recently known as the core concept necessary to realize a fully integrated CAD/CAM system. The information contents in a feature can be easily conveyed from one application to another in the manufacturing domain. However the feature generated in one application may not be suitable for another without being modified with more information. The objective of the paper is to present the methodology of decomposing bulky features of the sculptured shape of pocket to be removed into compact features to be efficiently machined. It is possible to reactively and efficiently machine the sculptured shape of pocket by segmenting horizontally and vertically a bulky feature and by applying variable cutting condition to each feature.     

A feasible approach to the integration of CAD and CAPP

Although current CAD systems are declared to be feature-based, in fact, the so-called feature is just a modeling macro or menu name such as Protrusion, Revolution, Cutout, Block, etc., instead of a design feature or manufacturing feature in accordance with engineering practice. Consequently, product model data insufficiency and incompatibility between varieties of application systems are still the major barriers to system integration, especially the integration of design and process planning. This paper proposes a practical solution for a bi-directional integration of CAD and CAPP on the platform of commercial CAD systems. The key techniques such as feature recognition and conversion, feature parameter and constraint extraction, feature tree reconstruction, technical information processing, process planning, automatic process drawing marking and 3D material stock CAD model generating are discussed. And the extracted features and their related technical information and knowledge are encapsulated together with the geometry-oriented CAD model to form an integrated product information model to facilitate effective integration with the downstream activities. The integrated CAD/CAPP system is implemented on a commercial CAD package, UGS/SolidEdge. A case study and industry implementation illustrate the feasibility of the approach proposed.     

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.     

An expert system approach for die and mold making operations

In the modern manufacturing of sophisticated parts with 3D sculptured surfaces, die and mold making operations are the most widely used machining processes to remove unwanted material. To manufacture a die or a mold, many different cutting tools are involved, from deep hole drills to the smallest ball nose end mills. Since the specification of each tool is very different from each other, each mold or die is specific with their complicated shapes and many machining rules exist to consider, a great deal of expertise is needed in planning the machining operations. An expert system (DieEX) developed for this purpose is described in the present work. The geometry and the material of the workpiece, tool material, tool condition and operation type are considered as input values and various recommendations about the tool type, tool specifications, work holding method, type of milling operation, direction of feed and offset values are provided.     

An application-independent methodology of feature recognition with explicit representation of feature interaction

The existing feature-based design and feature recognition methods cannot fulfil the requirements of automated process planning. It is now recognized that satisfactory modelling of interactions between features is necessary for developing an automated process planning system. The selection of an optimum manufacturing process for a part needs to be considered at the conceptual design phase to incorporate the capabilities and constraints of the process in design. This paper describes a methodology of feature recognition that is independent of manufacturing process and explicitly generates geometric feature interactions in a part. The paper illustrates generation of feature sets for shape-forming processes, and describes a method to convert the process-independent features into machinable volumes and tool paths for material removal processes.     

A hybrid system for SPC concurrent pattern recognition

Any nonrandom patterns shown in Statistical Process Control (SPC) charts imply possible assignable causes that may deteriorate the process performance. Hence, timely detecting and recognizing Control Chart Patterns (CCPs) for nonrandomness is very important in the implementation of SPC. Due to the limitations of run-rule-based approaches, Artificial Neural Networks (ANNs) have been resorted for detecting CCPs. However, most of the reported ANN approaches are only limited to recognize single basic patterns. Different from these approaches, this paper presents a hybrid approach by integrating wavelet method with ANNs for on-line recognition of CCPs including concurrent patterns. The main advantage of this approach is its capability of recognizing coexisted or concurrent patterns without training by concurrent patterns. The test results using simulated data have demonstrated the improvements and the effectiveness of the methodology with a success rate up to 91.41% in concurrent CCP recognition.     

Recognition of machining features for cast then machined parts

Mechanical parts are typically manufactured using multiple manufacturing processes. Primary processes such as casting realize the primary shape of the part, while secondary processes such as machining generate more detailed shape of the part. This paper presents a feature recognition method to support machining process planning for cast-then-machined parts. From the part model including the specification of machined faces, we generate the starting workpiece for machining, which represents the casting output in sufficient detail to support machining process planning. The starting workpiece is generated by identifying faces to be made by casting followed by machining, then offsetting the part through these faces by a uniform machining thickness to obtain cast faces, and combining the halfspaces induced by machined faces and the halfspaces induced by their bounding cast faces to enclose removal volumes. Machining features are then recognized from the removal volumes using a volume decomposition method called Alternating Sum of Volumes with Partitioning.     

工作流生成中的一种流程模式知识优化方法

基于模式的工作流生成利用规划技术和业务知识实现了工作流自动创建。流程模式知识的优劣直接影响到工作流生成结果的正确性。提出了一个针对流程模式的知识优化方法。在人工建模的基础上,针对流程模式知识构建场景分类器。利用流程规划运行的历史数据,通过机器学习对流程模式进行调整与优化,保证了工作流创建的正确性。     

An optimal orthonormal system for discriminant analysis

This paper proposes a new discriminant analysis with orthonormal coordinate axes of the feature space. In general, the number of coordinate axes of the feature space in the traditional discriminant analysis depends on the number of pattern classes. Therefore, the discriminatory capability of the feature space is limited considerably. The new discriminant analysis solves this problem completely. In addition, it is more powerful than the traditional one in so far as the discriminatory power and the mean error probability for coordinate axes are concerned. This is also shown by a numerical example.     

Development of an object-oriented blackboard model for stamping process planning in progressive die design

This paper reports preliminary work to investigate the suitability of using a blackboard framework as a problem-solving model for stamping process planning in progressive die design. The model is described at two levels: knowledge level and computational level. The knowledge level describes how the stamping process planning domain is represented in a blackboard architecture. The computational level describes how the blackboard architecture is modeled and implemented using object technology. A software prototype has been developed using CLIPS and C++ interfaced with Solid Edge CAD system. An example is presented to illustrate the feasibility and practicality of the proposed approach.     

Statistical modeling and feature selection for seismic pattern recognition

Application of pattern recognition techniques to reflection seismic data is difficult for several reasons. The amount of available training data is limited by the degree of well control in the area and may not be sufficient. In contrast, seismic data sets are often extremely large, necessitating the use of the smallest possible feature set to allow quick and efficient processing. In this paper, a method to generate synthetic training data is described, which alleviates the problem of insufficient training data. A means is provided for injecting a priori geologic knowledge into the classifier, including well logs. Finally, a feature evaluation algorithm using a performance metric related to the Bayes probability of error is outlined and applied to the training data to identify effective feature sets.     

An integrated methodology for fixture design

In this paper, a methodology to perform fixture design as an integrated aspect of process planning is proposed. A three-phase methodology for the fixture design activity has been developed. The three phases include predesign analysis (phase I), functional analysis (phase II), and productivity improvement (phase III). In phase I, the product design information is studied, and initial fixture design aspects are developed. In phase II, the clamping and location aspects of fixture design are addressed for the given initial process sequence and product design information. Phase III involves studying ways to increase the productivity including using simultaneous machining approaches, multiclustering, use of specialized jigs, etc.     

An integrated intelligent process planning system (IIPPS) for machining

A key component of computer integrated manufacturing (CIM) is computer aided process planning (CAPP). Process planning in machining involves the determination of the cutting operations and sequences, the selection of machine tools and cutting tools, the calculation of machining parameters, and the generation of CNC part programs. Industrial structures in Norway are defined as small and medium-sized companies. The important fact is how well these companies use high technologies and resources in order to improve their production efficiency, product quality, and company competition in international markets. The concept of an integrated intelligent system (IIS) is created for this purpose. A prototype system, the integrated intelligent process planning system (IIPPS), is described for machining; it was developed on the basis of an IIS and constructed using three levels of effort: (1) AutoCAD, (2) dBASE III and (3) KnowledgePro. The system may be utilized not only by a process plann ing engineer in a company, but also by students of mechanical or industrial engineering.     

新型电梯群控系统交通模式识别方法

电梯交通模式识别是电梯群控调度的一个关键问题.针对实时变化的电梯交通流数据,提出一种新型的电梯系统交通模式识别方法.在不增加数据采集量的基础上,首先对基本交通信息进行预处理,再采用多值分类的支持向量机算法,对电梯群控系统建立交通模式分类器.建立的分类器可以根据交通流数据的变化,自适应地识别出建筑物内的最大客流层及次大客流层(厅堂除外).仿真结果表明,这种交通模式识别方法能较准确地辨识出各种交通流模式,并且通过对比试验,证明该算法的识别准确率优于人工神经网络算法,体现出较好的泛化能力,实用性强.