1,721,045 research outputs found
A framework for an intelligent CNC and data model
No full textIn this paper, we present a conceptual framework for designing and implementing an intelligent CNC system. The architecture and functional modules are derived from requirement analysis, and they are designed to have a thinking capability before, during, and after the execution of the manufacturing task, so that the assigned task can be effectively executed while dealing with unexpected changes occurring on the shop floor. Also, the data model for supporting the architecture is addressed based on the STEP-NC data model or ISO 14649. Specifications of databases and the operational scenario together with implementation issues are provided. The framework presented can be used as a paradigm for STEP-compliant CNC.X1166sciescopu
FIVE-AXIS PART MACHINING WITH THREE-AXIS CNC MACHINE AND INDEXING TABLE
No full textIn this paper, we develop a versatile CAM method by which five axis machining can be effectively carried out with a three-axis CNC machine together with a rotary-tilt type indexing table. In this method, the part surface is divided into a set of subareas, and each subarea is machined by the virtually oriented tool whose orientation is provided via the index table. The key goal in developing our solution algorithm has been to minimizing the number of part setups (i.e., angle changes in the indexing table) and the surface ridges where multiple tool paths join. A robust algebraic solution procedure for achieving these practical criterial is presented, including the details of surface decomposition, tool path computation, and the interface of the index table. Since the developed method enables utilization of existing machines (equipped with three-axis control) for five-axis machining, the results are practically meaningful, especially for small to medium industries.X1116sciescopu
COLLISION-AVOIDANCE TRAJECTORY PLANNING USING TUBE CONCEPT - ANALYSIS AND SIMULATION
No full textX114sciescopu
Neural network modeling for tool path planning of the rough cut in complex pocket milling
No full textThis paper presents a new approach to rough-cut tool path planning of pocket milling operations. The key idea is to formulate the tool path problem into a TSP (traveling salesman problem) so that the powerful neural network method can be effectively applied. Specifically, the method is composed of (1) digitization of the pocket area into a finite number of tool points, (2) a neural network method (called a SOM-self-organizing map) for path finding, and (3) postprocessing for path smoothing and feed rate adjustment. By the neural network procedure, an efficient tool path (in the sense of path length and tool retraction) can be robustly obtained for any arbitrary shaped pockets with many islands. In postprocessing, (1) the detailed shape of the path is partially modified by eliminating sharp corners of the path segments and (2) any crossovers between the path segments and islands. With the determined tool path, the feed rate adjustment is finally performed for legitimate motion without requiring excessive cutting forces. The validity and powerfulness of the algorithm is demonstrated through various computer simulations and real machining.X1124sciescopu
A PROTOTYPE CAM SYSTEM FOR 4-AXIS NC MACHINING OF ROTATIONAL-FREE-SURFACES
No full textThe rotational-free surface (RFS) is a special type of free surface because two of its boundaries coincide. For NC machining of an RFS, a rotational axis as well as three Cartesian axes are required. In this paper, we develop a four-axis CAM system consisting of geometric modeling of RFS, CL-data generation, graphic simulation and verification, and postprocessing and communication. To test the validity and effectiveness of the developed system, several test cuts are made with an additional-four-axis CNC milling machine and are compared with the graphic simulation.X118sciescopu
Contouring performance measurement and evaluation of NC machine controller for virtual machining CAM system
No full textTo realise a virtual machining CAM system the machine tol accuracy together with the controller behaviour should be incorporate in the CAM system. For such a a purpose a ball-bar method is presented for measuring and verifying the circular positioning, contouring, and performance evaluation of a CNC controller. A parameter adjustment method for the enhancement of CNC controller errors was also proposed. First, a mathematical representation of the error patterns was defined, and transformed into contouring forms. By comparing the measured data with the defined controller error patterns, an analysis method was developed based on the "weighted residual method". The algorithms developed in this study were implemented in a software for extracting the error patterns of an NC controller from the measured contouring data using a ball-bar. The software is also able to suggest the parameter adjustment required to enhance the NC controller performance optimally.X116sciescopu
ISO 14649-based nonlinear process planning implementation for complex machining
No full textIncreasing attention is being paid to complete machining, i.e., machining of the whole part in a single machine tool, in the metal working industry. For this purpose, complex machine tools equipped with machining components, such as multiple spindles and turrets have been developed by leading machine tool builders. The efficiency of complex machine tools is largely dependent on how the machining components are utilized. The main thrust of this paper is twofold: (1) Proposition of a nonlinear process planning based on the STEP-NC (STEP-compliant data interface for numerical controls) paradigm whose data model is formalized as ISO 14649, and (2) Development of an optimal Solution algorithm for process planning for complex machining. The developed algorithm is based on the branch-and-bound approach and heuristics derived from engineering insights. The developed process planning method and optimization algorithm were implemented and tested via the TurnSTEP system developed by our research team. Through the experiments, we are convinced that the new process planning and algorithm can be used as a fundamental means for implementing the third type of STEP-NC [Suh S. TurnSTEP: Tools to create CNC turning programs. In: White paper presented on STEP Implementers' Forum ISO TC184/SC4 Meeting. 2004], i.e., an Intelligent and Autonomous STEP-NC system for the CAD-CAM-CNC chain supporting e-Manufacturing. (C) 2008 Elsevier Ltd. All rights reserved.X1127sciescopu
AVOIDING TOOL INTERFERENCE IN 4-AXIS NC MACHINING OF ROTATIONALLY FREE SURFACES
No full textThe four-axis NC configuration is suitable for the manufacture of a part family (called a rotationally free surface or RFS) requiring concurrent motions for the tool movement and part rotation. In this paper, we develop algorithms for handling tool interference in four-axis machining in which three types of interference exist: interference due to step size, tool size, and tool axis. The first two types are also present in three-axis machining, but the third type is unique and critical in four-axis machining. The performance of the developed algorithms is tested via graphic simulation and actual cutting. The results showed that the developed algorithms can be readily incorporated into existing CAD/CAM systems as a module for interference-free four-axis NC machining of an RFS.X118sciescopu
An architecture for ubiquitous product life cycle support system and its extension to machine tools with product data model
No full textProduct life cycle information is utmost important for the stakeholders involved from product design, manufacturing, through product retirement. However, information on products after they become available to the customer becomes vague or unrecognized. Furthermore, various real-time data from the shop floor or usage data from customers are not gathered in real time. To overcome this problem, we present an ubiquitous product life cycle support (UPLS) system based on the UbiDM: a new paradigm for design and manufacturing via ubiquitous technology proposed by our research center. Specifically, in this paper, we derive a generic architecture for the UPLS system based on the UbiDM and requirement analysis from the various functional- and data-level perspectives. As an extension, we apply the generic architecture for the machine tools by developing a life cycle data model to be used for the UPLS system for machine tools. The machine tools were taken as an example among the products considering the importance of every life cycle of the product (i.e., Begin-of-Life, Middle-of-Life, and End-of-Life) and the necessity of international standards under establishment by the ISO TC184/SC1 and SC4. The impact and validity of the developed architecture and data model were made by some realistic usage scenarios with the UPLS system incorporating the architecture and data model developed in this paper.X112124sciescopu
A VARIATIONAL DYNAMIC-PROGRAMMING APPROACH TO ROBOT-PATH PLANNING WITH A DISTANCE-SAFETY CRITERION
No full textX1124sciescopu
- …
