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High-Speed Incremental forming – New Technologies For Flexible Production Of Sheet Metal Parts

Procedia Manufacturing 2019年 27卷 21-26页

作者： M. Linnemann V. Psyk E. Djakow R. Springer W. Homberg D. Landgrebe Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 09126 Chemnitz Germany Paderborn University – Department of Forming and Machining Technology Pohlweg 47-49 33098 Paderborn Germany

High-speed forming technologies have a very high potential for shaping complex parts and constitute a key means of reducing a component’s weight. For many materials they offer advantages such as low tool cost, high tool flexibility and extended forming limits at room temperature,. Hence, stringent emission regulations can be fulfilled and essential resources are saved. The limited forming zone, however, makes it impossible to achieve flexible, cost-efficient production of complex large-surface parts by high-speed forming alone. In order to overcome this problem, this paper suggests two different innovative forming concepts which enhance the pulsed-power-driven, high-speed forming technologies of electrohydraulic forming and electromagnetic forming by applying an incremental strategy. The concept is presented for both technologies, with a description of the different setups required for achieving the incremental movement in the forming sequence, employing guide railsand an industrial robot. Advantages and limits are discussed, and first experimental results prove the feasibility and give an impression of the process potential.

关键词： Incremental Sheet forming Electromagnetic forming Hydroforming

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Minimally-invasive lag screw fixation technique for posterior malleolus fractures: A cadaveric study

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Foot & Ankle Surgery: Techniques, Reports & Cases 2024年第2期4卷 100385-100385页

作者： Fullarton, M., MSc Vidakovic, H., FRACS Kieser, D.C., PhD, FRACS Hammer, N., PhD Wyatt, M.C., MD, FRACS University of Otago Department of Anatomy Dunedin New Zealand University of Otago Department of Orthopaedics and Musculoskeletal Medicine Christchurch New Zealand Medical University of Graz Division of Macroscopic and Clinical Anatomy Gottfried Schatz Research Center Graz Austria Department of Trauma Orthopedic and Plastic Surgery University Hospital of Leipzig Germany Fraunhofer Institute for Machine Tools and Forming Technology Division of Biomechatronics Dresden Germany College of Health Massey University New Zealand

AbstractAnatomical reduction and lag screw fixation of posterior malleolar (PM) ankle fractures typically involves an open posterolateral approach. The aim of this anatomical study was to assess whether a minimally-invasive, percutaneous posterior-to-anterior lag screw fixation technique is safe to perform. Eighteen cadaveric ankle specimens were used. A transverse incision was made at the lateral border of the Tendo Achilles (TA). Windows were made lateral to and through the substance of the TA and simulated reduction and placement of a single lag screw performed. Specimens were then fully dissected to ascertain proximity and damage to anatomical structures. Lag screw fixation was placed appropriately in all ankles. No injury to the neurovascular structures, ankle joint or syndesmotic ligaments was observed. The mean distance from the soft tissue window to sural nerve was 10.0 mm (range 5–16), and 9.5 mm to short saphenous vein (4–14). Whilst the muscle belly of flexor hallucis longus (FHL) was pierced in six specimens, no injuries to the FHL tendon were observed. The mean distance from screw to syndesmosis was 9.3 mm (range 3–15) and 12.7 mm to the ankle joint (7–17). This study demonstrates that posterior percutaneous lag screw fixation is both safe and accurate. Further work is required to evaluate the precision of reduction and the biomechanical stability of this fixation technique. This novel minimally-invasive technique may be beneficial in avoiding the wound complications associated with open posterolateral ankle approaches and also offer a functional advantage due to minimal soft tissue disruption.

关键词： Ankle joint Approach Fixation Posterior malleolus fracture Trauma V

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Identification in the Frequency Domain of Mechanically Coupled Axes on Servo-Screw Presses

Identification in the Frequency Domain of Mechanically Coupl...

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International Conference on Control, Mechatronics and Automation (ICCMA)

作者： H. Kirchner J. Quellmalz H. Schlegel P. Müller Department of Control and Feedback Control Technology Technische Universität Chemnitz Germany Department of Forming Technology and Joining Fraunhofer Institut for Machine Tools and Forming Technology Dresden Germany

ISBN: (纸本)9781728137889

The article deals with the system identification of drive trains on forming machines. The aim is to analyze the mechanical properties in the frequency domain. A comparison of uncoupled single axes with several axes in a coupling system should provide information on whether different controller parameters or controller structures have to be adapted for both cases. This will be investigated using the example of an electromechanical die cushion on a servo screw press.

关键词： couplings dies (machine tools) fasteners forming processes presses servomechanisms press-in Servomechanism forming PROCESSES Fasteners Press Couplings axe Axis, Cervical Vertebra Frequency-domain analysis Axis Screw presses System identification coupling coupled system cushions

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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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Structural health monitoring for fibre reinforced composites produced by the winding process 22

Structural health monitoring for fibre reinforced composites...

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22nd International Conference on Composite Materials, ICCM 2019

作者： Naumann, Mario D. Körner, Enrico Heinrich, Michael Kroll, Lothar Department of Lightweight Structures and Polymer Technology Technical University of Chemnitz Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology Volkswagen AG Federal Cluster of Excellence MERGE Technical University of Chemnitz Chemnitz Germany Fraunhofer Project Center for Advanced Lightweight Technologies Opole Poland

In recent years, the power density as a ratio of internal pressure to mass of pressure vessels has steadily increased, which is particularly advantageous for the transportation of gases as fuel in vehicles. At the same time, high safety requirements combined with a high degree of lightweight construction usually correlate with an increased demand for cost-intensive high-performance materials. Also with the increasing introduction of hydrogen-powered vehicles, high safety measures play a central role for pressure vessels, which are usually serially manufactured. In order to provide progressive series solutions for this, new safety systems are moving into the focus of scientific efforts. Within the scope of intensive research work, the complete integration of a metallic sensor wire for the deformation measurement of a fibre-plastic composite pressure vessel as well as its functional verification is therefore being investigated. The structural integration of the sensor wire is based on a direct method, the so-called winding process. In the winding process, the reinforcing fibres are applied to a positive core. This results in closed moulded bodies in fiber reinforced plastic (FRP) design such as pipes, tanks, axles, pressure vessels and shafts. With the aid of a winding machine, a core (mandrel), which forms the shape of the component, is set in rotation and the reinforcing fibre is pulled off a creel with a defined yarn tension. At the same time, the sensor wire is fed through the same thread eye. The sensor wire thus follows the reinforcing fibre. This results in an exact positioning of the sensor wire along the reinforcing fibers and allows the measurement according to the stress of the composite structure. For the impregnation of the reinforcement fibres with the resin system, these are passed through a resin bath and then wound onto the mandrel. Furthermore, the impregnation of the sensor wires is carried out indirectly via contact of the sensor wires with the imp

关键词： Fiber reinforced plastics

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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

关键词： Kinematics

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Detection of the Force Distribution Close to the Effective Site in forming machines for a Force Control

Detection of the Force Distribution Close to the Effective S...

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International Conference on Control, Mechatronics and Automation (ICCMA)

作者： A. Schleinitz A. Sewohl H. Schlegel M. Putz Department of Control and Feedback Control Technology Technische Universität Chemnitz Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Germany

Ever higher demands are placed on the quality and complexity of formed sheet metal parts, whereby the efficiency of the processes may not be affected. Thus it becomes more difficult to ensure process stability. In order to reduce rejected parts it is necessary to improve forming technologies and processes. Closed loop control of process variables with an influence to the quality of a part is a promising approach. Therefor the reliable metrological acquisition of such a parameter is a basic requirement. forming force respectively force distribution has an influence on component quality and seems to be a suited value. In this paper, a measurement setup and its implementation in a demonstrator is described. First metrological examinations show occurring effects during eccentric load cases and the derivation of spindle forces via additional load paths in the machine frame. This knowledge will be used for the development of a force control.

关键词： Force Force measurement tools Presses Process control Sensor systems

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“Evaluation of a method to measure the friction coefficient between vital mandibular bone and biomedical materials”

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Biotribology 2021年 28卷

作者： Ben Achour, Anas Petto, Carola Meißner, Heike Mostofa, Anita Teicher, Uwe Ihlenfeldt, Steffen Lauer, Günter Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden 01187 Germany Department of Oral and Maxillofacial Surgery University Hospital Carl Gustav Carus Dresden Technische Universität Dresden Fetscherstraße 74 Dresden 01307 Germany Department of Prosthetic Dentistry University Hospital Carl Gustav Carus Dresden Technische Universität Dresden Fetscherstraße 74 Dresden 01307 Germany

Purpose: The aim of this study is to evaluate a developed experimental set-up to measure the coefficient of friction between fresh mandibular bone and biomaterials used in oral and maxillofacial surgery including a standardized routine for specimen preparation. Material and methods: For this purpose, we developed a specialized routine for harvesting and preparation of cortical bone specimen from cadaveric porcine mandibles and modified a ball-plate tribometer. These harvested bone specimen were kept moist all the time. A total of 24 bone cylinders with 8 repetitions per material were examined for their coefficient of friction against stainless steel (1.4404), a titanium alloy (Ti6Al4V) and a cobalt‑chromium‑molybdenum alloy (Biosil F®) and subsequently analyzed by laser-scanning and scanning electron microscopy. Results: The lowest coefficients of friction between vital cortical bone and the investigated implant materials were found for Biosil F®, while the highest coefficients of friction were found for the titanium alloy Ti6Al4V. Significant differences for the initial coefficient of friction with p < 0.05 have been proven. Stick-slip effects occurred during the measurement and a layer of debris formed on the metallic samples. EDX analysis of the abrasion marks revealed that this layer consisted of elements contained in hydroxyapatites and carbon. Conclusion: The experimental set-up is suitable to perform reproducible comparative measurements of the coefficient of friction of different material combinations. A significant advantage of the methodology is the flexibility and scalability of harvesting and preparation of the bone specimen, which allows the simulation of realistic situations while measuring the coefficient of friction. © 2021 Elsevier Ltd

关键词： Biotribology Bone Experimental Friction coefficient Implant materials Tribology

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Media Based forming and Injection Molding Based on Fiber Reinforced Plastic Tubes

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Procedia Manufacturing 2019年 27卷 166-171页

作者： A. Albert M. Werner D. Landgrebe W.-G. Drossel M. Layer U. Engelmann L. Kroll Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Department of Lightweight Structures and Polymer Technology Technische Universität Chemnitz 09107 Chemnitz Germany

Research and development for industrial applications forces Fraunhofer IWU to explore new fields of technology. The combination of Media Based forming and Injection Molding (MBF-IM) in a single process is such a new development to meet the requirements on lightweight design and resource efficiency. Based on over 20 years of Fraunhofer IWU experience in hydroforming, this technology development started with the usage of metal tubes and PA6 with glass fiber to produce metal-plastic-hybrid-components the structural strength of the component is realized by the formed metal tube while the molded attachment allows for easy functionalization. Cockpit cross beams (CQB) are known state of the art components produced this way. In a first development step the conventional hydroforming process was replaced by media based forming (MBF) using nitrogen as a pressure medium. With this process the tool can always be kept dry for the injection molding (IM) process without any additional effort, and no subsequent part cleaning is necessary. Together with TU Chemnitz and industrial partners further developments are continuously carried out and still under research. The focus of this strategic cooperation is the development and the usage of plastic tubes for the structural function of the component. The paper shows the development path from the state of the art for the MBF-IM from metal-plastic hybrid components to the replacement of the liquid active medium for the MBF by gaseous nitrogen, the use of endless fiber-reinforced plastic tubes as semi-finished products to the MBF-IM of short-fiber-reinforced plastic tubes.

关键词： Hydroforming Injection molding Fiber reinforced plastics manufacturing process

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Process-oriented Flow Curve Determination at Mechanical Joining

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Procedia Manufacturing 2020年 47卷 368-374页

作者： Mathias Jäckel Sam Coppieters Nelis Vandermeiren Christian Kraus Welf-Guntram Drossel Noa Miyake Toshihiko Kuwabara Klaus Unruh Heinrich Traphöner A. Erman Tekkaya Tudor Balan Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden 01187 Germany KU Leuven Technology Campus Ghent Department of Materials Engineering Gebroeders De Smetstraat 1 Ghent 9000 Belgium Belgium Welding Institute Technologiepark 48 Ghent 9052 Belgium Institute of Engineering Tokyo University of Agriculture and Technology 3 Chome-8-1 Harumicho Tokyo 183-8538 Japan Faurecia Autositze GmbH Nordsehler Straße 38 Stadthagen 31655 Germany Institute of Forming Technology and Lightweight Components TU Dortmund Baroper Straße 303 Dortmund 44227 Germany Arts et Metiers Institute of Technology Université de Lorraine LCFC HESAM Université F-57070 Metz France

The accuracy of numerical simulation models for forming processes depends highly on the method for the flow curve determination. Numerous experimental tests exist to identify the flow curves of sheet metals, each with certain characteristics regarding stress states and achievable strains. In this paper stress state analysis are presented for the mechanical joining techniques clinching as well as self-pierce riveting with semi-tubular rivet (SPR). Based on these findings flow curves for DC04 material are determined by selected experimental materials tests in order to compare the influence of the flow curve determination method on the accuracy of the process simulation models.

关键词： Mechanical Joining Material Chracterization Numerical Simulation

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