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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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Parallel computing in automation of decoupled fluid-thermostructural simulation approach

arXiv

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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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Non-cuttable material created through local resonance and strain rate effects (vol 10, 11539, 2020)

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SCIENTIFIC REPORTS 2020年第1期10卷 1-24页

作者： Szyniszewski, Stefan Vogel, Rene Bittner, Florian Jakubczyk, Ewa Anderson, Miranda Pelacci, Manuel Chinedu, Ajoku Endres, Hans-Josef Hipke, Thomas Durham University Durham United Kingdom Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Fraunhofer Institute for Wood Research Wilhelm-Klauditz-Institut WKI Hannover Germany Leibniz University Hannover Institute of Plastics and Circular Economy IKK Garbsen Germany University of Surrey Guildford United Kingdom University of Stirling Stirling United Kingdom

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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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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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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Miniaturized parallel kinematic machine tool for the machining of small workpieces 18

Miniaturized parallel kinematic machine tool for the machini...

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

作者： Georgi, Oliver Rentzsch, Hendrik Blau, Peter Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9780995775121

Machining small workpieces with large scale machine tools has several disadvantages such as high costs, low efficiency and higher sensitivity to errors. Miniaturizing the machine to workpiece scale is a suitable approach to overcome certain limitations. However, this measure also leads to significant changes in machine properties even if the kinematic structure remains unchanged. On the basis of a parallel kinematic machine tool the paper investigates size effects and machine characteristics during dimensioning and design process. Static stiffness of joint bearings and overall dynamic behaviour are analysed to derive and prove certain design measures. Furthermore the influence of miniaturization on structure synthesis and feed drive dimensioning is shown. The paper concludes with final design and specifications of the developed parallel kinematic machine tool. © 2018 CURRAN-CONFERENCE. All rights reserved.

关键词： machine tools

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Automatic bead position calculation for hem flange bonding

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Procedia Manufacturing 2019年 27卷 138-143页

作者： M. Eckert J. Weber B. Hecht W.-G. Drossel M. Rössinger Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Volkswagen Aktiengesellschaft Brieffach 011/1326 38436 Wolfsburg Germany

This article deals with improving the planning of hem flange bonding in the car body manufacturing process. Particularly during the ramp-up of the plant, great effort is put into ensuring that the generated adhesive bond meets the quality requirements. Here, several challenges occur in parallel. This ranges from the specific adhesive design, a result of multi-dimensional and individually curved car body parts, to the multi-stage process chain, where the associated manufacturing equipment is complex. This intricacy is countered by a discrete analysis of the adhesive continuum. Based on an established method, the location where the adhesive must be applied is computed under consideration of contiguous contours, disturbance variables and applicability by the projected dispensing system. For this reason the performance of the involved machines is examined. The results of this new method comprise a robot path along which an application system is guided, and control commands for the latter. Finally, a validation proves that this way, the adhesive application can be designed in a shorter period of time and in high quality at an early stage of plant design.

关键词： Computer automated process planning (CAPP) Robot Hem flange bonding

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Investigating the influence of bending parameters on the springback behavior of ultra-high strength spring strips 26th

Investigating the influence of bending parameters on the spr...

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26th MEFORM Conference on Resource Efficient Materials and forming Technologies, 2018

作者： Richter, Karsten Reuther, Franz Müller, Roland Landgrebe, Dirk Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9783035712971

The spring industry has to process ultra-high strength spring strips of the steel grade 1.4310 (X10CrNi18-8). Springback during bending is a limiting factor for resource-efficient production processes in the so-called stamping bending technology. This paper reports a mainly experimental investigation on the influence of bending parameters on the evolving springback of spring strips of the grade 1.4310 with tensile strengths TS = 1500-1800 MPa. © 2018 Trans Tech Publications, Switzerland.

关键词： Stamping

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Burnishing of prismatic workpieces on three-axis machine enabled by closed loop force control

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Procedia CIRP 2019年 81卷 1028-1033页

作者： Marco Posdzich Chris Schöberlein Johannes Quellmalz Matthias Putz Chemnitz University of Technology Institute for Machine Tools and Production Processes (IWP) Reichenhainer Str. 70. 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Reichenhainer Str. 88. 09126 Chemnitz Germany

Burnishing is an effective chipless finishing process for improving workpiece properties: hardness, vibration resistance and surface quality. The product quality and process stability are significantly influenced by factors such as tool movement and burnishing force. The implementation of a force controlled tool positioning enables integration of finish operations like burnishing into conventional machining centers. This paper shows the realization of this new machine and process technology. The controller structure and tuning are discussed. In addition, the effects on the process forces and the workpiece are examined.

关键词： control micro forming finishing

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Effects of cooling lubricant on the thermal regime in the working space of machine tools

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Procedia Manufacturing 2019年 33卷 327-334页

作者： Michael Bräunig Joachim Regel Janine Glänzel Matthias Putz Institute for Machine Tools and Production Processes Technische Universität Chemnitz Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

The use of cooling lubricant is indispensable for many milling and grinding machining tasks, primarily to achieve the best possible cooling and lubricating effect in the cutting zone and to reduce wear. In addition, tempered cooling lubricant carries out the function of heat removal from the working space. A reduction due to resource-efficient or ecological efforts has a direct impact on the temperature regime in the working space, which affects the thermal behavior of the frame structures and can cause machining inaccuracies. In this article, these effects of cooling lubricant on the thermal behavior of exemplary assemblies are modeled. Experimental investigations, based on temperatures and displacements, are compared with simulation-based calculations. The results include the description of the environmental conditions that must be taken into account when modeling frame structures and the influencing variables such as coolant temperature, supplied volume flow and extracted air volume.

关键词： machine tool thermal analysis cooling system CFD-simulation thermal modeling

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