2 research outputs found

    ESDA2008-59473 HIGH STIFFNESS CLOSED-FORM KINEMATIC STRUCTURAL DESIGN OF A LOW- COST 4/5-AXIS MICRO/MESO-SCALE INVERTED HIGH-SPEED MACHINING CENTER

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    ABSTRACT The demand for miniaturized components is increasing in various industries, such as the biomedical, consumer electronics, optics and defense-related industries. The production of the micro/meso-scale components and parts in these industries is typically undertaken using MEMS-type photolithographic production techniques that have limitations in the materials and geometries that can be produced. However, numerous research efforts during the course of the last five to ten years have developed micro-scale EDM processes, microlaser processes and micro-machining operations. In particular, the micro-machining processes have been demonstrated to provide a credible solution to the production of micro/mesoscale parts with complexes geometries in a broad range of materials. The development of mMTs is growing with the rapidly increasing demand for tighter tolerances. Traditionally, mMTs have been developed based on horizontal or vertical Cartesian co-ordinate machine tool structures. However, as the need for increased process flexibility and productivity is continuously being driven higher, there is a need to develop higher degree of freedom machining systems, including 4-axis and 5-axis machining centers. In this paper, the design of a low-cost, high-precision, high-speed 4/5-axis micro/meso machining center is presented as a cost-competitive alternative to existing open-form kinematics precision machining centers. A key departure from traditional machine tool design approach that has been adopted in this design is the utilization of closedform kinematic structural design to create a high-stiffness, lowcost machine tool base. In addition, the lower thermal mass of the mMT base enhances rapid thermal washout in the structure and significantly reduces the thermal gradients in the structure. Consequently the thermal errors present in the structure are limited and simply and adequately handled using existing error compensation strategies. Initial results from an analytical and numerical investigation of the thermo-mechanical response of an innovative, kinematically closed-form inverted micromachining center are presented. A coarse resolution parametric study was undertaken to evaluate the preferred preferred design space for maximum stiffness and minimum thermal distortion in low-cost, high precision, high-speed micro-machining centers. In addition, in order to facilitate part loading and unloading operations will be considered as a key design characteristic. A key result of this study has been the identification of a preferred design space for kinematic form selection, material selection and structural design options for increased rigidity, reduced thermal error and reduced production costs for flexible 4/5-axis micro/meso-scale machining centers. The proposed mMT design achieves a 3X increase in rigidity over a comparable tradition kinematically open horizontal mMT system INTRODUCTION The demand for miniaturized components is increasing in various industries, such as the biomedical, consumer electronics, optics and defense-related industries. The production of the micro/meso-scale components and parts in these industries is typically undertaken using MEMS-type photolithographic production techniques that have limitations in the materials and geometries that can be produced. However, numerous research efforts during the course of the last five to ten years have developed micro-scale EDM processes, micro-laser processes and micro-machining operations. In particular, the micro-machining processes have been demonstrated to provide a credible solution to the production of micro/meso-scale parts with complexe geometries in a broad range of materials. The development of mMTs is growing with the rapidly increasing demand for tighter tolerances. While the pace of development of mMT technology has accelerated during the recent past, the remaining limiting factors for micro-mechanical machining are the miniaturization of the components, tools, and processe

    Analysis on micro milling dynamics and stability

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    Smaller sizes are becoming more and more necessary for industry. Literally, machining features less than one millimeter are called micro machining. Milling using small or mini tools is one of the most common manufacturing processes for production of precision products. As in the macro milling, milling with mini tools also suffer from well known unstable vibration problem which is called regenerative chatter. Chatter prediction models need certain process, tool and workpiece related information. Tool tip frequency response function FRF is the key input information for cutting dynamics and chatter stability analyses. The common method for determining macro tool tip FRF is the experimental modal analysis. However, in micro tools receptance coupling analysis is popular in the literature due to certain restrictions of experimental test method. This thesis is focused on determining dynamic parameters of miniature milling tools by modal testing methods which are crucial to determine the stability characteristics of the micro flat end milling. An indirect modal testing method is presented. Also stability limit prediction with a conventional model is compared with experimental results. Various chatter detection methods and milling conditions are tested. In process chatter detection problems and modelling difficulties related with the miniature tool geometry are reported. Tool dynamics prediction is done with certain accuracy. Although the thesis study lacks from solid results in the stability limit prediction, discrepancy analysis of the test data are done and it is a first step for further studies
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