6,162 research outputs found

    The Development of a Technological Processor as a Part of a Workpiece Programming System

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    The cost of turning on NC-lathes is substantially sensative to cutting conditions. The use of optimum cutting conditions is limited by a large number of constraining factors such as chip disposal, chucking possibility, available power, required accuracy etc. The present way of work preparation, even when using the available workpiece programming systems, does hardly allow of generating acceptable values for the cutting variables. Moreover, the combination of geometrical and a technological processor in one workpiece programming system will save substantial time in work preparation.\ud Starting from a former reported development, this article deals with the development of a technological processor of improved design and extended possibilities, as for instance the handling of the chucking problem, as a part of a complete workpiece programming system. At choice the output of this processor may be presented in graphes, showing the limited working area and indicating the preferential working point.\ud Another feature is the possibility of automatic tool selection by comparing the working area of the machine tool with the working areas of the different potential tools.\ud The overall system design is modular and well structured to further portability and flexibility

    Towards a novel design method for impact on leading edges

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    Results of a parametric study concerning low velocity impact on leading edge profiles is presented. This work is the first part of a larger program on the development of an engineering design method for impact on Glare. In this first part, experimental tests and numerical simulations on two-dimensional aluminium leading edge profiles were carried out. An extensive parametric study was done using numerical analysis. Selected configurations have been validated using impact tower testing. Impact tests were done with a solid impactor with a circular diameter on leading edges having a width of 20 mm. Profiles with three different thicknesses and three different sizes were tested. Impact velocities were in the range 1 to 8 m/s. The numerical models predicted the deformation of the leading edges accurately. Important impact parameters were identified and relations were established between impact parameters and geometrical properties of the leading edge profiles. The obtained results give important insight in the set up of simulations and experimentation and in the identification of important parameters of leading edge impact

    Strategy in Generative Planning of Turning Processes

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    This paper reports on the process and operations planning system ROUND and the strategies which underlie the decision making processes in the planning of turning operations. At first, an outline is given about the environment for which generative systems like ROUND are being developed. The differences between high volume production and job shop production, with respect to flexibility and productivity, are designated. The impact of automation on job shop production and its consequences for process and operations planning are discussed. In small batch manufacturing systems, relatively large amounts of process planning data have to be processed, which leads to an increasing interest for sophisticated computer aided process planning tools. Because available NC part programming systems usually do not support the generation of reliable and economic technological data, it is necessary to develop generative process and operation planning systems. Due to the relative complexity of the technological models, generative systems use a lot of computing power. Reduction of possible variants, combined with model refinement are techniques which are used in ROUND, in order to avoid excessive iteration. This is illustrated by the explanation of strategies which are implemented in two newly developed modules: The clamping module RNDFIX and the module for selection of tools for the roughing operation RNDRTL

    Review of research in feature-based design

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    Research in feature-based design is reviewed. Feature-based design is regarded as a key factor towards CAD/CAPP integration from a process planning point of view. From a design point of view, feature-based design offers possibilities for supporting the design process better than current CAD systems do. The evolution of feature definitions is briefly discussed. Features and their role in the design process and as representatives of design-objects and design-object knowledge are discussed. The main research issues related to feature-based design are outlined. These are: feature representation, features and tolerances, feature validation, multiple viewpoints towards features, features and standardization, and features and languages. An overview of some academic feature-based design systems is provided. Future research issues in feature-based design are outlined. The conclusion is that feature-based design is still in its infancy, and that more research is needed for a better support of the design process and better integration with manufacturing, although major advances have already been made

    Injection of Ballistic Hot Electrons and Cool Holes in a Two-Dimensional Electron Gas

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    We have constructed a novel magnetic spectrometer to study the dynamics of hot electrons and cool missing electron states injected by quantum point contacts in the two-dimensional electron gas of a GaAs-AlxGa1-xAs heterostructure. The mean free path of these quasi-particles is found to be longer than recent theoretical estimates. The injection energy of the particles is found to be anomalously low as the point contact approaches pinch-off, and also for high bias voltages.

    'Create the future': an environment for excellence in teaching future-oriented Industrial Design Engineering

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    In 2001, the University of Twente started a new course on Industrial Design Engineering. This paper describes the insights that have been employed in developing the curriculum, and in developing the environment in which the educational activities are facilitated. The University of Twente has a broad experience with project-oriented education [1], and because one of the goals of the curriculum is to get the students acquainted with working methods as employed in e.g. design bureaus, this project-oriented approach has been used as the basis for the new course. In everyday practice, this implies a number of prerequisites to be imposed on the learning environment: instead of focusing on the sheer transfer of information, this environment must allow the students to imbibe the knowledge and competences that make them better designers. Consequently, a much more flexible environment has to be created, in which working as a team becomes habitual, and where cutting-edge technologies are available to facilitate the process. This can be realized because every student owns a laptop, with all relevant software and a full-grown course management system within reach. Moreover, the learning environment provides the fastest possible wireless network and Internet access available [2]. This obviously has its repercussions on the way the education is organized. On the one hand, e.g. virtual reality tools, CAD software and 3D printing are addressed in the curriculum, whereas on the other hand more traditional techniques (like sketching and model making) are conveyed explicitly as well. Together with a sound footing in basic disciplines ranging from mathematics to design history, this course offers the students a profound education in Industrial Design Engineering. The paper describes in more detail the curriculum and the education environment, based on which it is assessed if the course on Industrial Design Engineering can live up to its motto: ‘Create the future’, and what can be done to further enable the students to acquire the full denotation of that motto

    Tone-burst technique measures high-intensity sound absorption

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    Tone-burst technique, in which narrow-bandwidth, short-duration sonic pulse is propagated down a standing-wave tube, measures sound absorbing capacity of materials used in jet engine noise abatement. Technique eliminates effects of tube losses and yields normal-incidence absorption coefficient of specimen
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