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Modeling elastic behavior of forming machine components to reduce tool manufacturing time

Procedia Manufacturing 2019年 27卷 177-184页

作者： R. Tehel T. Päßler M. Mihm Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany ALLGAIER Automotive GmbH Ulmer Straße 75 73066 Uhingen Germany

In the domain of sheet metal forming for car bodywork the deep drawing process is one of the essential operations and finishes with the calibration of the final contour in the bottom dead center. At this point the demand for great accuracy is opposed to the highest press force inducing large deformations of the tool and the machine itself. The tool deformation is known from CAD and FEM, whereas the compensation of the machine elasticity is currently carried out only in a global and general way. This paper describes a workflow for the measurement and analysis of the individual elastic behavior of a forming machine’s most relevant components and their conversion into a FE model which is capable to be used in a simulation together with the tool geometry for determining the individual compensational camber of the tool. This workflow targets the enhancement of the current general empirical values with an individual deterministic approach for each machine and tool combination to reduce the overall time for tool manufacturing.

关键词： forming Tool geometry Finite element method (FEM)

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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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Methodology for the design of recursively axially formed rotor shafts made of two or more combined segments

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Procedia Manufacturing 2019年 27卷 13-20页

作者： R. Kurth R. Tehel T. Päßler H. Wagner D. Beihofer Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Felss Systems GmbH Dieselstraße 2 75203 Königsbach-Stein Germany

Electric drives are used in all industrial fields in a growing number. Whereas the rotor shafts used in the area of machinery and plant engineering are designed as solids, the shafts mainly used in the field of automotive industry are hollow shafts focusing on the lightweight potential and the improvement of motor characteristics. This paper describes a shaft design consisting of two or more segments manufactured by a new combination of certain cold forming processes before joining. This design enables higher flexibility of variants as well as optimization of production efficiency and logistic chains. Thus, the joint zone design is a special serration with a helix angle in order to reach a high robustness of the shaft. A detailed FEM simulation of the elastoplastic behavior of the joint zone and the mechanical characteristics of the complete shaft leads to an evaluation of possible applications of this joint geometry and the corresponding manufacturing process. Based on experimental investigations, the simulations have been validated successfully. An empirical model designed by regression analysis of further simulation results is used to propose a design methodology for the identification of design parameters of the assembled shaft and the joint zone as well. These parameters can be used for planning the forming processes and the blank geometry.

关键词： forming rotor shaft finite element method (FEM) axial forming rotary swaging joining serration

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Microstructured multifunctional polymer chips by UV-photopolymerization injection molding 18

Microstructured multifunctional polymer chips by UV-photopol...

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

作者： Hackl, C. Griebel, J. Elsner, C. Edelmann, J. Abel, B. Leibniz Institute of Surface Modification IOM Leipzig Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

ISBN: (纸本)9780995775121

In this paper we present a very promising procedure for fabrication of double-sided structured foils by UV photopolymerization based injection molding process. By using different acrylates (urethane- and epoxy-based, mono- and multifunctionalized) it is possible to control the mechanical parameters of the produced polymer films, e. g. Young's modulus, transition temperature, brittleness. For the polymerization TPO-L is used as an UV initiator. Mechanical properties as well as molding quality of the films prepared by UV-induced injection molding were compared to hot-embossed poly(carbonate) films of the same layout. Problems during demolding were discussed and an improvement by non-adhesive coatings of the tool inserts and the lid-glass is illustrated. Furthermore, we demonstrated the flexibility of the process by successfully tuning the wettability of the poly(acrylate) films from hydrophilic (water contact angle of 30°) to hydrophobic (water contact angle of 106°) by adding suitable additives to the acrylate mixture, e. g. sulfopropyl acrylate or C16/C18 alkyl acrylate derivatives. In this respect, the filling of the microfluidic channels with a test solution in dependence of the water contact angle was also investigated. The UV-induced injection molding approach promises high flexibility regarding the properties of the resulting films, possible future applications are the fabrication of multilayer films or films with spatially separated areas with different wettability. Based on this idea we present first results of the utilization of a complex tool which allows for the injection of two different acrylate mixtures. © 2018 CURRAN-CONFERENCE. All rights reserved.

关键词： Polymer films

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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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Combined and fast computable thermal models for situationally optimal tempering of machine tool components

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Procedia CIRP 2019年 79卷 608-613页

作者： Juliane Weber Janine Glänzel Jens Popken Linart Shabi Jürgen Weber Institute of Fluid Power TU Dresden Helmholtzstr. 7a 01069 Dresden Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

The focus of this paper is on the modeling of an existing machine frame with its cooling structures. An overview is given of all the modeling methods used, their respective sub-targets and their interactions with each other. The modeling workflow encompasses both the mechanical and fluidic properties of the machine frame, including the fluid circuits and their control. The study results are the different requirements for modeling and the achievable result accuracy with regard to the temperature and deformation field. It forms the basis for the subsequent investigation of various temperature control variants, which are not part of this paper.

关键词： machine tools machine frame Cooling system Modeling CFD FEM Network-based 1D modeling

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Adapted scan strategy and slicing tool for improvement of strut precision in lattice structures

Adapted scan strategy and slicing tool for improvement of st...

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2018 ASPE and euspen Summer Topical Meeting on Advancing Precision in Additive Manufacturing

作者： Korn, Hannes Koch, Peter Kordaß, Richard Holtzhausen, Stefan Schöne, Christine Müller, Bernhard Stelzer, Ralph Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz / Dresden Saxony Germany Institute of Machine Elements and Machine Design Technische Universität Dresden Dresden Saxony Germany

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Correction to: Properties of a superelastic NiTi shape memory alloy using laser powder bed fusion and adaptive scanning strategies

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Progress in Additive Manufacturing 2021年第1期7卷 139-139页

作者： Gustmann, Tobias Gutmann, Florian Wenz, Franziska Koch, Peter Stelzer, Ralph Drossel, Welf‑Guntram Korn, Hannes Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany Fraunhofer Institute for High-Speed Dynamics (Ernst-Mach-Institut) EMI Freiburg Germany Fraunhofer Institute for Mechanics of Materials IWM Freiburg Germany Chair of Engineering Design and CAD Technical University Dresden Dresden Germany

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Basic material and technology investigations for material bonded hybrids by continuous hybrid profile fabrication

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IOP Conference Series: Materials Science and Engineering 2021年第1期1140卷

作者： K Schubert M Gedan-Smolka A Marschner T Rietzschel K Uhlig D Löpitz D Wagner M Knobloch Leibniz-Institut für Polymerforschung Dresden e.V. (IPF) Hohe Straße 6 01069 Dresden Germany Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Reichenhainer Straße 88 09126 Chemnitz Germany

The development of multi-material hybrids by injection molding has been studied very intensively at the IPF in the past. For that, a material bonding between the different substrates was achieved by using a newly developed two-step curing powder coating material as latent reactive adhesive. The aim of the project 'Hybrid Pultrusion' was to perform a novel approach for the fabrication of material bonded metal-plastic joints (profiles) in a modified pultrusion process. Therefore, powder pre-coated steel coil is combined with a glass-fiber reinforced epoxy resin matrix. For initial basic studies, the impregnated fiber material has been applied on the pre-coated steel sheets using the Resin Transfer Molding process (RTM-process). It was proved via lap shear tests, that this procedure resulted in very high adhesive strengths up to 35 MPa resulting from the formation of a covalent matrix-steel bonding as well. In addition, the failure mechanism was subsequently studied. Furthermore, by adapting the successful material combination to the pultrusion process it was demonstrated that material bonded hybrids can be achieved even under these continuous processing conditions.

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A novel hybrid clamping system for sheet metals and thin walled structures

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Procedia Manufacturing 2019年 40卷 51-55页

作者： Uwe Teicher Sebastian Pirl Andreas Nestler Arvid Hellmich Steffen Ihlenfeldt Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden 01187 Germany Technische Universität Dresden Institute of Manufacturing Technology Dresden 01062 Germany Technische Universität Dresden Institute of Mechatronic Engineering Dresden 01062 Germany

Thin sheets and thin-walled structures are of great economic importance in the aerospace industry due to the enormous efforts being made in lightweight construction. The challenge in machining is to use a reliable clamping device to take account of the sheet metal or component structure as well as to work productively and reliably. For this purpose, a hybrid clamping system has been developed that functions on the basis of vacuum and the adhesive properties of a carrier medium in order to form a complex joining. This method was verified by material tests and then developed to make it usable for the HSC and HPC milling of aluminum sheets. For this purpose, demonstrator parts were manufactured in order to test the critical loads of this clamping system on the one hand and to produce structures that cannot be realized economically with other machining methods on the other hand.

关键词： clamping fixture machining sheet metal aluminum

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