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Preparation of symmetrical and asymmetrical cutting edges on solid cutting tools using brushing tools with filament-integrated diamond grits

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Procedia CIRP 2020年 93卷 873-878页

作者： T. Bergs S.A.M. Schneider M. Amara P. Ganser Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstrasse 17 52074 Aachen Germany

The manufacturing of asymmetric cutting edges is crucial for tool life and performance of cutting tools. For rotationally symmetric cutting tools with a complex profile of the cutting edges, such as milling or drilling tools, no suitable preparation methods exist so far. This paper presents a model that describes the targeted preparation of symmetrical and asymmetrical cutting edges using abrasive brushing tools with filament-integrated diamond grits in dependence of various process parameters. The selected process parameters and dimensions of the brushing tool ensure the accessibility of real cutting tools. In addition, the results of investigations on brushing tool wear are presented.

关键词： machining cutting edge preparation brushing cutting tool microgeometry

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Kinematics of the Lumbo-Pelvic Complex under Different Loading Conditions

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Current Directions in Biomedical Engineering 2019年第1期5卷 347-349页

作者： Weidling, Martin Voigt, Christian Wendler, Toni Heilemann, Martin Werner, Michael Jarvers, Jan-Sven Heyde, Christoph-E. Center for Research on Musculoskeletal Systems (ZESBO) Faculty of Medicine University of Leipzig Semmelweisstrasse 14 Leipzig Germany Center for Research on Musculoskeletal Systems (ZESBO) 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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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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Parallel computing in automation of decoupled fluid-thermostructural simulation approach

arXiv

引用

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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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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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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Design model for a value chain-oriented quality management in global tooling

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Procedia CIRP 2020年 93卷 1013-1018页

作者： Thomas Bergs Marcel Prümmer Christian Lürken Kristian Arntz Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany

The globalization of production has current effects on the tooling industry. Customer proximity, fast reaction times and a worldwide service range are significant selling propositions for market positioning of a toolmaking company. Nevertheless, high quality standards are indispensable to distinguish from the international competition. The developed quality management model includes three design modules giving different approaches for quality improvement in tool manufacturing. Additionally, digitalization solutions to support the implementation of quality gates in single batch production are presented. Furthermore, five main target aspects have been developed for a framework of a value chain-oriented QM model for global producing tooling companies.

关键词： quality management tooling value chain process optimization risk management error management data quality tool quality quality gates digitalization

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Numerical Investigation of Damage in Single-step, Two-step, and Reverse Deep Drawing of Rotationally Symmetric Cups from DP800 Dual Phase Steel

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Procedia Manufacturing 2020年 47卷 636-642页

作者： Matthias Nick Andreas Feuerhack Thomas Bergs Till Clausmeyer Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Institute of Forming Technology and Lightweight Components of TU Dortmund Baroper Str. 303 44227 Dortmund Germany

Damage evolution in deep drawing processes has an influence on the service properties of manufactured components. Knowledge and control of the damage state will therefore allow a reduction in safety factors and, consequently, in sheet thickness. To investigate the damage after deep drawing of rotationally symmetric cups, a Lemaitre type damage model calibrated in previous works was used in the Finite Element (FE) simulation of the deep drawing process. Three process variants were investigated: single-step deep drawing, two-step deep drawing, and reverse deep drawing. The single-step deep drawing process was used as a reference to evaluate the damage evolution in two-step and reverse deep drawing. In both two-step and reverse deep drawing, the overall damage values did not decrease when compared to single-step deep drawing. However, in reverse deep drawing specifically, the location of maximum damage in the cup wall was moved from an area near the cup floor towards the edge of the cup. In real-life components, this control over the location of maximum damage will allow a tailoring of the damage state in the component to the expected service loads, thereby increasing service life or allowing a reduction in sheet thickness, respectively.

关键词： damage deep drawing dual phase steel

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Experimental investigations on the influence of temperature for Laser Metal Deposition with lateral Inconel 718 wire feeding

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Procedia CIRP 2020年 94卷 29-34页

作者： Thomas Bergs Sebastian Kammann Gabriel Fraga Jan Riepe Kristian Arntz Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 Aachen 52074 Germany Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 Aachen 52074 Germany

In the present work, the thermal history influence on Inconel 718 thin-wall structures fabricated by wire-based Laser Metal Deposition (LMD-w) was analyzed. To perform the depositions, a novel processing head with wire force and gas nozzle temperature monitoring was employed. Based on the thermal radiation a temperature threshold for a stable process could be defined. General process trends and typical defects as cracks, pores and lack of fusion are also discussed. Additionally, Scanning Electron Microscope (SEM) images and Energy Dispersive Spectroscopy (EDS) were employed to verify the influences of different cooling rates and the deposition strategy on the microstructure. Finally, to verify the resulting mechanical properties, hardness measurements were performed on each sample. It was found that, for thin-wall fabrication by LMD-w, heat accumulation can adversely affect the build-up. Therefore, cooling of interlayers is suggested as a strategy to mitigate such a problem.

关键词： wire-based Laser Metal Deposition (LMD-w) Inconel 718 Thermal radiation Thin-walled structures Laser additive manufacturing

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Thermo-viscoelastic Modeling of Nonequilibrium Material Behavior of Glass in Nonisothermal Glass Molding

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Procedia Manufacturing 2020年 47卷 1561-1568页

作者： Anh Tuan Vu Tim Grunwald Thomas Bergs Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany

Nonisothermal Glass Molding (NGM) has become a viable replicative manufacturing technology for the cost-efficient production of complex precision optical components made of glass. During the pressing stage in NGM, glass materials undergo a huge temperature change in the glass transition range. In this range, glass exhibits thermo-viscoelastic responses, and the temperature drop through the glass transition leads glass structure to depart from an equilibrium to a nonequilibrium state. Thermo-viscoelastic properties of the nonequilibrium glass material greatly depend on temperature and thermal history. This paper presents a phenomenological constitutive model developed for modeling the thermo-viscoelastic responses of nonequilibrium glass. We propose a direct incorporation of the temperature -and thermal history effects into each parameter of the phenomenological model. This novelty allows the model to describe the nonequilibrium phenomena and to study temperature-dependent viscoelasticity of glass without assuming thermo-rheologically simple characteristics. Furthermore, the phenomenological model enables the coupling of structural -and stress relaxation phenomena. The model validation conducted for creep experiments demonstrates an enhancement in numerical predictions of the nonequilibrium material behaviors of glass over wide ranges of temperature and thermal history.

关键词： Nonisothermal glass molding thermo-viscoelastic modeling nonequilibrium viscoelasticity structural relaxation

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