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arXiv 2019年

作者： Glänzel, Janine Naumann, Andreas Kumar, Tharun Suresh Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Dresden University of Technology Institute of Scientific Computing Dresden Germany

Decoupling approach presents a novel solution/alternative to the highly time-consuming fluidthermal-structural simulation procedures when thermal effects and resultant displacements on machine tools are analyzed. Using high dimensional Characteristic Diagrams (CDs) along with a Clustering Algorithm that immensely reduces the data needed for training, a limited number of CFD simulations can suffice in effectively decoupling fluid and thermal-structural simulations. This approach becomes highly significant when complex geometries or dynamic components are considered. However, there is still scope for improvement in the reduction of time needed to train CDs. Parallel computation can be effectively utilized in decoupling approach in simultaneous execution of (i) CFD simulations and data export, and (ii) Clustering technique involving Genetic Algorithm and Radial Basis Function interpolation, which clusters and optimizes the training data for CDs. Parallelization reduces the entire computation duration from several days to a few hours and thereby, improving the efficiency and ease-of-use of decoupling simulation approach. Copyright © 2019, The Authors. All rights reserved.

关键词： machine tools

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Working Gap Analysis in Electrochemical Precision Machining of External Geometries with Ring Cathodes

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Procedia CIRP 2020年 95卷 662-667页

作者： Ingo Schaarschmidt Matthias Hackert-Oschätzchen Gunnar Meichsner Philipp Steinert Mike Zinecker Andreas Schubert Professorship Micromanufacturing Technology Chemnitz University of Technology 09107 Chemnitz Germany Chair of Manufacturing Technology with Focus Machining Otto von Guericke University Magdeburg 39106 Magdeburg Germany Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

Pulsed electrochemical machining (PECM) with oscillating cathode is a non-conventional manufacturing technology to machine complex precision geometries independent from the mechanical properties of the workpiece material. PECM with oscillating cathode is an advanced development of conventional ECM by applying a pulsed electric current in conjunction with an oscillating movement of the cathode. Result is electrochemical precision machining with a more stable process combined with better accuracy and quality. This work focuses on the analysis of the resulting side working gap in electrochemical precision machining of external geometries by applying PECM. Therefore, the height of a ring cathode was varied to adjust the cathode inner surface. The resulting side working gap was studied through multiscale multiphysics simulation applying COMSOL Multiphysics as well as experiments applying a PEMCenter 8000. As main result, the increase of the resulting side working gap as consequence of an increasing cathode inner surface will be analysed in detail.

关键词： Pulsed electrochemical machining (PECM) Side working gap Multiscale multiphysics modelling

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Data Mining and machine Learning Methods Applied to A Numerical Clinching Model

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Computer Modeling in Engineering & Sciences 2018年第12期117卷 387-423页

作者： Marco Gotz Ferenc Leichsenring Thomas Kropp Peter Müller Tobias Falk Wolfgang Graf Michael Kaliske Welf-Guntram Drossel Institute for Structural Analysis Technische UniversitatDresdenGermany Fraunhofer Institute for Machine Tools and Forming Technology DresdenGermany

Numerical mechanical models used for design of structures and processes are very complex and high-dimensionally *** understanding of the model characteristics is of interest for engineering tasks and subsequently for an efficient *** analysis methods are known and available to gain insight into existing *** this contribution,selected methods from various fields are applied to a real world mechanical engineering example of a currently developed clinching *** selection of introduced methods comprises techniques of machine learning and data mining,in which the utilization is aiming at a decreased numerical *** methods of choice are basically discussed and references are given as well as challenges in the context of meta-modelling and sensitivities are *** incremental knowledge gain is provided by a step-bystep application of the numerical methods,whereas resulting consequences for further applications are ***,a visualisation method aiming at an easy design guideline is *** visual decision maps incorporate the uncertainty coming from the reduction of dimensionality and can be applied in early stage of design.

关键词： Design data mining computational intelligence meta-modelling permissible design space sensitivity analysis self-organizing maps inverse problem early stage of design clinching

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Tool System for UV induced micro moulding of biomedical disposables 18

Tool System for UV induced micro moulding of biomedical disp...

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18th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2018

作者： Edelmann, J. Gärtner, E. Eckert, U. Griebel, J. Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Leibnitz IOM Leipzig Germany

ISBN: (纸本)9780995775121

A new approach for the generation of double-sided microstructured polymer films is presented based on injection-molding of urethane- and epoxy-based acrylates that are polymerized by irradiation with ultraviolet light (395 nm). Compared to hot embossing, this offers not only working under ambient conditions, but also a reduction of cycle time as well as flexibility regarding adjustment of the mechanical and/or chemical properties of the resulting polyacrylate film. A setup, consisting of the mold with the microstructured insert and two LED lamps emitting UV-light moved by a controllable stepper motor and a computer-based controller, was installed and successfully used for the fabrication of double-sided microstructured polyacrylate films. Therefore a new and innovative tool system for 2-component UV induced micro moulding of biomedical disposables was developed. The geometrical dimensions of the microstructures (e.g. fins, channels, sharp edges and slopes) require different technologies to machine the tool inserts. Therefore micromilling and μ-laserablation technologies were used in combination attached by laser polishing operations in special areas. A highly precise, complex designed tool system with mechanically moveable areas is needed to fill the tool with the 2 various chemical compositions. The paper presents the tool concept and explains the investigated surface treatment options. © 2018 CURRAN-CONFERENCE. All rights reserved.

关键词： Micromachining

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Effect of sample geometry on the macroscopic shear deformation of the titanium alloy Ti-10V-2Fe-3Al subjected to quasi-static and dynamic compression-shear loading

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IOP Conference Series: Materials Science and Engineering 2021年第1期1147卷

作者： S Winter M Scholze M F-X Wagner Institute of Materials Science and Engineering Materials Science Group Chemnitz University of Technology 09125 Chemnitz Germany now at Fraunhofer Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany

We investigate the evolution of shear bands in a Ti-10V-3Fe-2Al alloy with three different initial microstructures: solution-annealed β-titanium, β-titanium with primary α-phase precipitates as well as a condition with primary and secondary α-phase precipitates. Quasi-static and dynamic testing of compression-shear specimens with strain rates of 10-3 s-1 and 102 s-1 is performed at room temperature. The influence of two different sample geometries on the macroscopic shearing tendency is investigated: samples with a cylindrical cross section and samples with a square cross section. The results of digital image correlation and the nominal stress-strain behavior under quasi-static and dynamic loading indicate a stronger localization tendency of the aged conditions with additional α-phase precipitates compared to the solution-annealed pure β-condition. Our results also demonstrate that compression-shear testing with samples with a square cross-section reduces facet loss, increases the resolution even at high strain rates and therefore allows to analyze strain distributions during shear band formation and propagation with higher accuracy.

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Simulation of dressing process for continuous generating gear grinding

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Procedia CIRP 2019年 79卷 280-285页

作者： Jonas Böttger Simon Kimme Welf-Guntram Drossel Institute for Machine Tools and Production Processes IWP Chemnitz University of Technology Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

Requirements for process accuracy in generating gear grinding are particularly high when it comes down to low noise emission of gears. Coincidentally, dressing has crucial influence on the grinding process and the flank topography of gear wheels, whereas the number of investigations focusing on the dressing process is fairly small. In order to examine the impact of dressing errors on the flank surface of the grinding worm, this work deals with the development of a kinematic cutting model for dressing using truing rolls. Apart from required simulation accuracy, the influence of selected dressing errors and corresponding process parameters is discussed.

关键词： Dressing Grinding Gear Simulation

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Nondestructive testing of composite fibre materials with hyperspectral imaging : Evaluative studies in the EU H2020 FibreEUse project

arXiv

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arXiv 2021年

作者： Yan, Yijun Ren, Jinchang Zhao, Huan Windmill, James F.C. Ijomah, Winifred de Wit, Jesper von Freeden, Justus National Subsea Centre Robert Gordon University Aberdeen United Kingdom Dept. of Electronic and Electrical Engineering University of Strathclyde Glasgow United Kingdom Dept of Design Manufacturing & Engineering Management University of Strathclyde Glasgow United Kingdom INVENT GmbH Christian-Pommer-Straße 47 Braunschweig38112 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Hermann-Münch-Str. 1 Wolfsburg38440 Germany

Through capturing spectral data from a wide frequency range along with the spatial information, hyperspectral imaging (HSI) can detect minor differences in terms of temperature, moisture and chemical composition. Therefore, HSI has been successfully applied in various applications, including remote sensing for security and defense, precision agriculture for vegetation and crop monitoring, food/drink, and pharmaceuticals quality control. However, for condition monitoring and damage detection in carbon fibre reinforced polymer (CFRP), the use of HSI is a relatively untouched area, as existing non-destructive testing (NDT) techniques focus mainly on delivering information about physical integrity of structures but not on material composition. To this end, HSI can provide a unique way to tackle this challenge. In this paper, with the use of a near-infrared HSI camera, applications of HSI for the non-destructive inspection of CFRP products are introduced, taking the EU H2020 FibreEUse project as the background. Technical challenges and solutions on three case studies are presented in detail, including adhesive residues detection, surface damage detection and Cobot based automated inspection. Experimental results have fully demonstrated the great potential of HSI and related vision techniques for NDT of CFRP, especially the potential to satisfy the industrial manufacturing environment. © 2021, CC BY.

关键词： Nondestructive examination

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Kinematics of the Lumbo-Pelvic Complex under Different Loading Conditions

Kinematics of the Lumbo-Pelvic Complex under Different Loadi...

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作者： Weidling, Martin Voigt, Christian Wendler, Toni Heilemann, Martin Werner, Michael Jarvers, Jan-Sven Heyde, Christoph-E. Faculty of Medicine University of Leipzig Semmelweisstrasse 14 Leipzig Germany Faculty of Medicine University of Leipzig Leipzig Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany Department of Orthopaedic Trauma and Plastic Surgery University Hospital Leipzig Leipzig Germany

The lumbo-pelvic complex is a highly complex structural system. The current investigation aims to identify the kinematics between interacting bone segments under different loading conditions. A specimen of the lumbo-pelvic complex was obtained from a human body donor and tested in a self-developed test rig. The experimental setup was designed to imitate extension, flexion, right and left lateral bending and axial rotation to the left and to the right, respectively. The vertebra L3 was firmly embedded and load was introduced via hip joints. Using a digital image correlation (DIC) system, the 3D motions of 15 markers at different landmarks were measured for each loadcase under cyclic loading. For each loadcase, the kinematics were analyzed in terms of three-dimensional relative movements between L3 and the sacrum. The usefulness of the experimental technique was demonstrated. It may serve for further biomechanical investigations of relative motion of sacroiliac and vertebral joints and deformation of bony structures. © 2019 by Walter de Gruyter Berlin/Boston.

关键词： Kinematics

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Influence of cutting edge radius on process forces in orthogonal machining of carbon fibre reinforced plastics (CFRP)

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Procedia CIRP 2019年 85卷 218-223页

作者： Konstantin Sauer Marco Witt Matthias Putz Institute for Machine Tools and Production Processes Chemnitz University of Technology 09111 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

Carbon fibre reinforced plastics (CFRP) are commonly used in the aerospace and automotive industries to reduce the mass of parts and assemblies with the goal of improving energy efficiency. When machining with geometrically defined cutting edge, the cutting edge radius of the tool is a quality-determining feature and should be kept as low as possible to enable precise separation of the fibres. It is raised by the use of coatings and by cutting edge wear. The aim of this paper is to evaluate the influence of the cutting edge radius on thrust force and cutting force when machining CFRP using an orthogonal cut. It is intended to map the drilling process by means of an orthogonal cut at certain fibre cutting angles. A new method of orthogonal machining has been developed for this purpose that considers the fibre preload and the feed movement of a drill. The fibre orientation was varied in the tool cutting edge plane. The application of small depths of cut in combination with different cutting edge radii enable the investigation of the effect of different cutting edge regions on the process forces. For this purpose, a new method for cutting edge preparation is proposed, based on the abrasive waterjet. Accordingly, the paper increases the understanding of the process when machining with high cutting edge radius.

关键词： Composite Cutting edge Machining Orthogonal cut CFRP Process force

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Dry sheet metal forming of aluminum by smooth DLC coatings – a capable approach for an efficient production process with reduced environmental impact

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Procedia Manufacturing 2020年 43卷 642-649页

作者： T. Abraham G. Bräuer F. Flegler P. Groche M. Demmler Fraunhofer-Institut for Surface Engineering and Thin Films Bienroder Weg 54E 38108 Braunschweig Germany Institute for Production Engineering and Forming Machines Technische Universität Darmstadt 64287 Darmstadt Germany Fraunhofer-Institut for Machine Tools and Forming Technology Reichenhainer Straße 88 09126 Chemnitz Germany

Currently a high amount of lubricants is used in aluminum forming processes to ensure a long tool lifetime and a high product quality. These technological and economical goals are traded for a negative environmental impact caused by the usage of lubricants. One approach to reduce the environmental impact is the utilization of dry forming of aluminum. Therefore, alternative methods for a tribological optimization need to be implemented like the deposition of tool coatings. Diamond like carbon (DLC) coatings are well known for their exceptional tribological properties. However, state of the art DLC coatings fail due to rapid formation of aluminum adhesions. In this paper, the nanoscopic roughness of DLC coatings will be presented as a critical property for preventing the formation of aluminum adhesions and enabling dry forming of aluminum. For this purpose, an amorphous hydrogenated carbon (a-C:H) coating will be deposited, subsequently polished and characterized to validate the impact of the material selection and surface treatment on the coating roughness. For an evaluation of the tribological properties, polished and unpolished a-C:H coatings will be tested in application oriented strip drawing and industry-oriented deep drawing tests. These tests demonstrate the capability of smooth a-C:H tool coatings to enable dry forming of aluminum with a reduced environmental impact.

关键词： Tribology Coating Metal forming

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