284 research outputs found

    Topological model for machining of parts with complex shapes

    Get PDF
    Complex shapes are widely used to design products in several industries such as aeronautics, automotive and domestic appliances. Several variations of their curvatures and orientations generate difficulties during their manufacturing or the machining of dies used in moulding, injection and forging. Analysis of several parts highlights two levels of difficulties between three types of shapes: prismatic parts with simple geometrical shapes, aeronautic structure parts composed of several shallow pockets and forging dies composed of several deep cavities which often contain protrusions. This paper mainly concerns High Speed Machining (HSM) of these dies which represent the highest complexity level because of the shapes' geometry and their topology. Five axes HSM is generally required for such complex shaped parts but 3 axes machining can be sufficient for dies. Evolutions in HSM CAM software and machine tools lead to an important increase in time for machining preparation. Analysis stages of the CAD model particularly induce this time increase which is required for a wise choice of cutting tools and machining strategies. Assistance modules for prismatic parts machining features identification in CAD models are widely implemented in CAM software. In spite of the last CAM evolutions, these kinds of CAM modules are undeveloped for aeronautical structure parts and forging dies. Development of new CAM modules for the extraction of relevant machining areas as well as the definition of the topological relations between these areas must make it possible for the machining assistant to reduce the machining preparation time. In this paper, a model developed for the description of complex shape parts topology is presented. It is based on machining areas extracted for the construction of geometrical features starting from CAD models of the parts. As topology is described in order to assist machining assistant during machining process generation, the difficulties associated with tasks he carried out are analyzed at first. The topological model presented after is based on the basic geometrical features extracted. Topological relations which represent the framework of the model are defined between the basic geometrical features which are gathered afterwards in macro-features. Approach used for the identification of these macro-features is also presented in this paper. Detailed application on the construction of the topological model of forging dies is presented in the last part of the paper

    Process Planning Optimization For Five-Axis Sculptured Surfaces Finishing

    Get PDF
    Ph.DDOCTOR OF PHILOSOPH

    Automated Process Planning for Five-Axis Point Milling of Sculptured Surfaces

    Get PDF
    Ph.DDOCTOR OF PHILOSOPH

    FIBR3DEmul-an open-access simulation solution for 3D printing processes of FDM machines with 3+actuated axes

    Get PDF
    This paper introduces a virtual emulator software for additive manufacturing (AM) processes based on filament deposition, the FIBR3DEmul. The presented software is capable of reading and parsing a G-Code file (ISO/DIN 66025), and realistically emulating a custom-designed 5-axis printer or a standard 3-axis Cartesian printer. The FIBR3DEmul was designed and implemented in two separate applications for reusability and scalability. First, the G-Code Interpreter is responsible for parsing the g-code script, controlling the flow of its execution, and notifying the user about detected printer-printer or printer-workpiece collisions. The second application involves the robotics simulator tool V-Rep. A custom plugin was implemented to mediate the communication with the Interpreter application, to generate the tool trajectories, to emulate the extrusion process, and to handle motion execution and collision detection. The process of designing and implementing a custom-printer control and motion execution in these two software is described. The performance of the virtual 5-axis printer was compared with the real machine in terms of position and velocity profiles. Results show a tight match between virtual and real printer-generated plots. The presented solution can also be extrapolated to CNC machines or WHASPs. The FIBR3DEmul source code is publicly available.FRCT - Fundo Regional para a Ciência e Tecnologia(POCI-01-0145-FEDER-016414

    Five-axis tool path generation using piecewise rational bezier motions of a flat-end cutter

    Get PDF
    Master'sMASTER OF ENGINEERIN

    New Approaches to Determining Shortest Cutters and Work Piece Setups without Over-travel for 5-axis CNC Machining

    Get PDF
    Five axis CNC machining centers are widely used in the industries for producing the complex parts. Due to two more axes as compared to the three axes machining, it provides the efficient and flexible way of the machining. Besides this flexibility, accidental collision possibilities between the cutting system and the other moving parts of the machine tools are also increased. These collisions could be avoided by changing the orientations of the tool during the tool path planning or by adjusting the cutter length and the tool holder size after the tool path generation in the part coordinate system. Collision detection and removal by the optimum cutter length depends on the configuration of five axis machine tools. No. of possible candidates for the collision may vary with the configuration of the machine tools. Since the fully utilization of the existing machining facilities in the industry is also in high demand, therefore, after selecting the one of the critical parameter of the cutter length, the maximum utilization of the work space of the 5-axis machine tools is another critical task. This dissertation comprises of two main works. In the first research work, a comprehensive approach for the determination of the optimum cutter length for the specific configuration of five axis machine tool is developed. The complete cutting system (the tool, the tool holder and the spindle), the work in process model and the fixture are the three possible candidates for the collision. The work in process model and the fixture are represented as the point cloud data and the tool holder and the spindle are represented as a regular shape of the truncated cone and the cylinder respectively. Collision checking is conducted in two steps. In the first step the KD-tree data structure is employed on the point cloud data and a method is developed which confines the searching of the point cloud data in the local region and in the second step a new mathematical model for the collision detection between the points in the local region and the cutting system is established. This model also has the capability of removal collision with the optimum cutter length. In the second research work, kinematics of the table rotating and spindle tilting 5-axis machine is developed and setup parameters for mounting the part on the table are defined. A precise method for the determination of the setup parameters, which gives the opportunity of fully utilization of the work space of the machine tool, is developed. Many machining simulation software such as vericut can simulate the G-codes for the given setup parameters of the part and can verify the over travel limits of the machine tool as well as accidental collision between the moving parts of the machine. In this research, the developed method for the determination of the setup parameters gives the guarantee of complete machining of the part without over travel limits of the machine translational axes. This research is based on the predetermined machining strategies, which means, tool path is already given in the part coordinate system

    Automatic tool path generation for multi-axis machining

    Get PDF
    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (leaves 67-72).We present a novel approach to CAD/CAM integration for multi-axis machining. Instead of redefining the workpiece in terms of machining features, we generate tool paths directly by analyzing the accessibility of the surface of the part. This eliminates the problem of feature extraction. We envision this as the core strategy of a new direct and seamless CAD/ CAM system. We perform the accessibility analysis in two stages. First, we triangulate the surface of the workpiece and perform a visibility analysis from a discrete set of orientations arranged on the Gaussian Sphere. This analysis is performed in object space to ensure reliability. For each triangle, a discrete set approximation of the accessibility cone is then constructed. Next, a minimum set cover algorithm like the Quine-McCluskey Algorithm is used to select the minimum set of orientations from which the entire workpiece can be accessed. These set of orientations correspond to the setups in the machining plan, and also dictate the orientation in which the designed part will be embedded in the stock. In particular, we bias the search for setups in favor of directions from which most of the part can be accessed i.e, the parallel and perpendicular directions of the faces in the workpiece. For each setup, we select a set of tools for optimal removal of material. Our tool-path generation strategy is based on two general steps: global roughing and facebased finishing. In global roughing, we represent the workpiece and stock in a voxelized format. We perform a waterline analysis and slice the stock into material removal slabs. In each slab, we generate zig-zag tool paths for removing bulk of the material. After gross material removal in global roughing, we finish the faces of the component in face-based finishing. Here, instead of assembling faces into features, we generate tool paths directly and independently for each face. The accessibility cones are used to help ensure interference- free cuts. After the tool paths have been generated, we optimize the plan to ensure that commonalities between adjacent faces are exploited.by Laxmiprasad Putta.S.M

    Visualization And Collision Detection Of Direct Metal Deposition

    Get PDF
    Direct metal deposition (DMD) is a manufacturing technique that manufactures solid metal parts from bottom to top using powdered metal and a focused laser. In this research, the swept volume technique was used as framework to develop a computer program to perform volumetric visualization of the deposition process as a pre-processor, before the actual metal deposition commences

    Robot Manipulators

    Get PDF
    Robot manipulators are developing more in the direction of industrial robots than of human workers. Recently, the applications of robot manipulators are spreading their focus, for example Da Vinci as a medical robot, ASIMO as a humanoid robot and so on. There are many research topics within the field of robot manipulators, e.g. motion planning, cooperation with a human, and fusion with external sensors like vision, haptic and force, etc. Moreover, these include both technical problems in the industry and theoretical problems in the academic fields. This book is a collection of papers presenting the latest research issues from around the world
    corecore