Automatic generation of machining information from a design system has been the research focus in feature-based cad/capp/cam applications for many years. Design data from a cad model cannot be directly used in a capp ...
详细信息
Automatic generation of machining information from a design system has been the research focus in feature-based cad/capp/cam applications for many years. Design data from a cad model cannot be directly used in a capp system due to the difficulties arising from different feature viewpoints in each application and in various feature representations. To create a process-planning model automatically using machine features, feature mapping or conversion is the key issue to solve this problem. This paper addresses the problem of how to convert the design feature representation into machining feature representation in a mathematical model. Design features in the design domain are represented by a set of faces of each feature geometry and a set of attributes such as dimensions and material feature. Machining features in the manufacturing domain are represented by a number of faces and relationships between these faces that are meaningful for the process/machining operations. Using a mathematical description of the feature mapping process, machining features can be deduced and formed by the Set Operation, and the difficult problem of feature interaction can be described mathematically and converted in theory. On the basis of feature representations in the design and manufacturing domains, the mathematical model of feature mapping is represented by a mapping function g(d-m) which is a synthesis function of the process mapping functions g(1) and g(2). The first function, g(1), extracts the topological elements of a feature from a design model, and forms its own face model which including an interactive feature topological elements. The second function, g(2), groups these extracted elements into a machining feature according to the geometrical relationship between these elements and matches them with the pre-defined machining features. Examples are given in this paper to show the procedure of the feature mapping process. A feature-based cad/capp/cam integration system is descri
cad/cam development over the past few decades has significantly improved design and manufacturing efficiency. Although cad, capp and cam technology has advanced greatly, the links between these systems are still weak....
详细信息
cad/cam development over the past few decades has significantly improved design and manufacturing efficiency. Although cad, capp and cam technology has advanced greatly, the links between these systems are still weak. Currently the information from cad and capp systems cannot be interpreted directly by cam systems. It is the users who interpret the information and make the connection between cad and cam systems. The current method to generate tool paths and NC programs, especially machining geometry preparation, involves extensive manual interactions in a cam system. To improve production efficiency further, a tighter cad/camintegration is needed to automate the design-to-manufacturing process. The paper discusses the automation of tool path generation in an integrated cad/capp/cam system based on machining features. Machining features are utilized to carry machining geometry information from capp to cam systems. An integration layer between FBMach and Unigraphics is implemented to achieve an integrated cad/capp/cam system based on machining features. The integration layer makes product information as well as process information available immediately in an electronic form for the preparation of tool paths. The integrated system automates the process of tool path generation from solid models and significantly reduces user interactions and the amount of time preparing tool paths.
This paper highlights the importance of integration between process planning and scheduling in flexible manufacturing systems (FMS). An effective integration increases the potential for enhanced system performance and...
详细信息
This paper highlights the importance of integration between process planning and scheduling in flexible manufacturing systems (FMS). An effective integration increases the potential for enhanced system performance and enhanced decision making. A framework that integrates flexible process plans with off-line (predictive) scheduling in FMS is presented The flexibility in process planning, including process flexibility, sequence flexibility, and alternative machine tools, is discussed. The proposed framework consists of four integrated stages with the objective of reducing the completion time. The integrated stages include: 1. Machine tool selection. 2. Process plan selection. 3. Scheduling. 4. Re-scheduling modules. In addition, the paper proposes a new approach, namely the Dissimilarity Maximisation Method (DMM), for selecting the appropriate process plans for a part mix where parts have alternative process plans. The recursive structure of the framework provides a different approach, namely overlapping schedules, which considers a longer scheduling period as comprising several short scheduling periods. Knowing that neither the process plans nor the planned (predicted) schedules are truly followed on the shop floor the related literature and the corresponding approaches are compared in order to envisage new approaches for closing the gap between process planning and scheduling.
An integrated cad/capp/cam system of tube manufacturing based on integration frame is presented. In this system, two kinds of data conventions describing tube shape are presented in tube cad subsystem, the object-orie...
详细信息
An integrated cad/capp/cam system of tube manufacturing based on integration frame is presented. In this system, two kinds of data conventions describing tube shape are presented in tube cad subsystem, the object-oriented concept and the goal-driven inference mechanism have been applied in the development of the knowledge-based capp subsystem and simulation of tube processing under tube bending simulation subsystem is performed based on the tube model＇s piecewise representation. A tube product case is considered to give the application of the integrated system, and the advantages of the system in the use of tube bending are revealed.
This paper uses semantic data modelling and cad/capp/cam integration to analyze the features defined in the STEP AP214, its characteristics of definition and distribution, and its influence on the complexity of cad/CA...
详细信息
This paper uses semantic data modelling and cad/capp/cam integration to analyze the features defined in the STEP AP214, its characteristics of definition and distribution, and its influence on the complexity of cad/capp/cam application integration. A framework is developed for applications of cad/capp/cam integration based on the STEP to reduce the complexity of integration implementation. Two application program interfaces (API), namely, application protocol API and application API, are developed. The frameworks hierarchy structure and the application program interfaces between the layers make the integration of applications easier.
暂无评论