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Load and energy management for factories through multi-stage production planning and optimization

Procedia CIRP 2019年 80卷 257-262页

作者： Marian Süße Bastian Prell Johannes Stoldt Hanns-Martin Strehle Mark Richter Andreas Schlegel Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany

The production phase has a major influence on the embodied energy of many products and, thus, their overall environmental performance. As a result, manufacturing enterprises are prompted to raise their energy efficiency and flexibility to improve their products’ sustainability. The simultaneous integration of renewable energy sources and decentral storages is a feasible option in this but also require consistent solutions for appropriately planning and controlling the operation of the entire factory system. This paper proposes an iterative multi-stage heuristic optimization for intelligent load and energy management. A load profile of the production plan, based on the minimized overall makespan, is checked against the available energy supply to identify demands and opportunities to shift single jobs based on calculated buffer times. Whenever infeasibility is determined, the process returns to the previous production planning stage for further alterations. This cycle is initiated regularly (e.g. weekly) or following certain events (e.g. long-lasting machine failure) and terminates once all restrictions are observed or if a termination threshold (e.g. calculation time) is reached. The experimental setup used for developing and validating this approach to energy-aware factory operation makes use of a probabilistic material flow simulation model. It provides information on tasks to be scheduled and executes production plans to evaluate the performance of the proposed solution. This new approach to energy-aware factory operation also provides opportunity to integrate additional ecologic criteria to improve the sustainability of manufactured products.

关键词： Energy efficiency Production planning Optimization Simulation

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Screening-based evidence of the impact of geometrical deviations on inner stresses on mechanical presses

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Procedia Manufacturing 2019年 27卷 185-191页

作者： N. Wagner T. Päßler Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany

In recent years various cases of damage analysis have shown an increasing number of overload scenarios resulting in failures of entire press structures. This happens in spite of manufacture-compliant utilization and a correct press design process based on state-of-the-art methods such as FEM simulation. This paper proves the hypothesis that geometrical tolerances, defined clearances and geometrical signs of wear have a significant impact on residual stress of a press, by conducting an empirical sensitivity analysis. The focus is on mechanical presses with four-point leverage actuation as an example for highly over-determined press structures. As proven by FEM simulation, the identified geometrical deviations result in a preload of the press structure, amounting up to 10% of its theoretical sustainable stress. The significant impact of geometrical deviations on the residual stress has been proven successfully for the empirically determined assumption.

关键词： Press Tolerancing Residual stress

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Increasing flexibility of self-pierce riveting using numerical and statistical methods

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Procedia Manufacturing 2019年 29卷 264-270页

作者： Tobias Falk Mathias Jäckel Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany

Self-pierce riveting with semi-tubular rivets (SPR-ST) is currently the most important joining technology for modern mixed-material car body constructions. In these body designs a multitude of material and thickness combinations occurs and for many of these combinations individual parameters of the SPR-ST process like the rivet length and die geometry have to be determined. This paper shows an approach to increase the flexibility of the SPR-ST process by the determination of the process parameters using FEM simulations in combination with statistical methods. In the described investigations one parameter set is derived for the SPR-ST process from seven different material combinations with steel and aluminum materials. For each material combination a simulation model is validated by the comparison of the joint geometry and force-stroke diagram from the experimental reference joints with the results from the process simulation. On the basis of the validated simulation models, numerical sensitivity analyses are carried out for each material combination to investigate the correlations between the process parameters die geometry and rivet length with important quality characteristics of the joint like interlock, minimal thickness of the die-sided sheet and joining force. With the knowledge of these studies computed process optimizations are carried out, in order to define one die geometry to join all seven material combinations in good quality, so a tool changing is no longer required. The reduction from seven to only one optimized SPR-ST tool saves costs as well as processing time and production space.

关键词： Self-pierce riveting Sensitivity analyses Tool optimization

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Production planning for optimal mass pre-distribution for axial feed cross rolling

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Procedia Manufacturing 2019年 27卷 192-196页

作者： N. Schubert J. Steger M. Gerlach B. Lorenz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 09126 Chemnitz Germany

At present, the process selection, the selection of tools and tool materials are key functions for the economic efficiency of manufacturing lines. The continuous improvements in production technology, including the related machine and tooling technology, have made it possible to increase both economic efficiency and resource efficiency in production. As a result of the market demand for a high variety of products and the constant change in the demand structure, the requested volume of individual product types is reduced – the trend towards small-series production is constantly increasing. In hot bulk forming processes, it is usually not possible to produce the workpiece in just one forming step. As an alternative to the well-known machining processes for optimized preforms, the axial feed cross rolling process was developed from wedge cross rolling. Due to the all-purpose tools, the use of this process is already economical for very small batch sizes. In order to achieve optimum results with regard to optimized mass pre-distribution, the process parameters during rolling must be kept within close limits. If this is the case, axial feed cross rolling allows additional material savings of between 12% and 15% compared to other preforming processes. In order to achieve best results, the preform operation is designed by using FE simulation axial feed cross rolling.

关键词： Hot deformation Production planning Finite element method (FEM)

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Inverse hybrid laminate for lightweight applications 5th

Inverse hybrid laminate for lightweight applications

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5th International Conference on Composite Materials and Material Engineering, ICCMME 2020

作者： Osiecki, Tomasz Gerstenberger, Colin Timmel, Tristan Frankiewicz, Mariusz Dziedzic, Robert Scholz, Peter Kroll, Lothar Institute of Lightweight Structures and Polymer Technology Technische Universität Chemnitz Reichenhainer Str. 31-33 Chemnitz09126 Germany Wroclaw University of Science and Technology ul. Lukasiewicza 5 Wroclaw50-371 Poland Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 Chemnitz09126 Germany Opole University of Technology Prószkowska 76 Street Opole45-758 Poland

ISBN: (纸本)9783035716191

Because of their high specific stiffness and strength, fiber reinforced plastics (FRP) are preferred lightweight materials. Recent developments show a growing industrial interest in the integration of thermoplastic FRP in complex structures for high volumes. However, there are still shortcomings for these materials concerning the insufficient energy absorption in case of failure and the limited opportunities available for the assembly with other components. Improvements in the crash performance can be achieved for instance with the selective reinforcement of the FRP structure with ductile metallic inserts. The present study shows the interlaminar shear strength and scanning electron microscope (SEM) samples of a novel load optimized hybrid composite consisting of a continuous fiber-reinforced thermoplastic matrix, in which a metal core is integrated. © 2020 Trans Tech Publications Ltd, Switzerland.

关键词： Fiber reinforced plastics

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Thermal errors in milling: Comparison of displacements of the machine tool, tool and workpiece

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Procedia CIRP 2019年 82卷 389-394页

作者： M. Putz J. Regel A. Wenzel M. Bräunig Chemnitz University of Technology 09010 Chemnitz Germany Fraunhofer-Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany

The paper describes an experimental method for quantifying the proportions of thermal errors of the machine tool, tool and workpiece in the total thermal error. For this purpose, the workpiece was subsequently measured and both the machine-internal and additionally built-in measuring sensors were used to quantify displacement errors. The static errors must also be detected. Based on the measured values, thermal states are calculated by regression analysis and included in the evaluation. The percentages of the single errors were calculated and gave a clear statement about the time sequences and the thermal influence of the components regarding to the total error in a milling process. The results allow an assessment of relevant areas that contribute to positioning errors.

关键词： experimental investigation thermal error machine tools milling

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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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Process development for self-pierce riveting with solid formable rivet of boron steel in multi-material design

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Procedia Manufacturing 2019年 29卷 271-279页

作者： Thomas Grimm Welf-Guntram Drossel Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany

Mechanical joining techniques are important joining processes for the implementation of lightweight structures in automotive engineering and other branches of industry. However, existing processes such as self-pierce riveting with semi-tubular rivet (SPR-ST) or solid rivet (SPR-S) reach their limits in certain applications, e.g. joining press-hardened boron steel sheets in multi-material constructions of automotive bodies. A new method to join these materials reliably and with high quality is the self-pierce riveting with solid formable rivet (SPR-SF). This paper shows different problems during the mechanical joining of press-hardened steel 22MnB5 by conventional SPR-S and illustrates the numerical as well as the experimental development of the new rivet concept: the solid formable rivet. On the basis of validated simulation models for conventional SPR-S numerical sensitivity analyses are carried out to investigate the correlations between the rivet properties (geometry parameters, material) and important quality characteristics of the joint like interlock, punching force and upsetting force for the new SPR-SF joining process. With the knowledge of these studies, specific rivet geometries are determined and prototypes manufactured for joining the material combination EN AW-6016 T4 ( t = 1.5 mm) into 22MnB5 ( t = 1.2 mm) in good quality. So, the application potential of the new SPR-SF is shown.

关键词： Self-pierce riveting Sensitivity analysis Boron steel Multi-material joining technology

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Considering energy-related factors in the simulation of logistics systems 19

Considering energy-related factors in the simulation of logi...

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Proceedings of the Winter Simulation Conference

作者： Moritz Poeting Bastian Prell Markus Rabe Tobias Uhlig Sigrid Wenzel TU Dortmund University Dortmund Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Universität der Bundeswehr München Neubiberg Germany University of Kassel Kassel Germany

ISBN: (纸本)9781728132839

Traditionally, aspects such as emissions and energy consumption have to be taken into account for environmental and economic reasons when it comes to transport. In other areas of logistics, such as production logistics and intralogistics, the energy aspect is also becoming increasingly important. Existing literature has been recently reviewed in a contribution of the Arbeitsgemeinschaft Simulation (ASIM) to the Winter Simulation Conference 2018 (Uhlig et al. 2018) to develop a map of common approaches and best practices for manufacturing and logistics systems. In the paper presented here, as a complement we are focusing on the application of energy simulation in logistics to give a comprehensive overview and present exemplary case studies. Furthermore, we show a classification of approaches to combine energy aspects with simulation. Finally, we will discuss open questions and future trends in this field of research.

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Additive manufacturing technologies for next-generation powertrains

Additive manufacturing technologies for next-generation powe...

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International Electric Drives Production Conference (EDPC)

作者： Philipp Fiedler Sebastian Stelzer Nikolaus Milaev Robert Richter Frank Kaulfuß Thomas Windisch Jan Bräunig Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany 3D-Printpetrol Großenhain Germany Fraunhofer Institute for Material and Beam Technology IWS Dresden Germany Division Engineering of Adaptive Systems Fraunhofer IIS/EAS Fraunhofer Institute for Integrated Circuits Dresden Germany

ISBN: (数字)9781728184586

ISBN: (纸本)9781728196145

The paper addresses the prototypical development and implementation of an innovative and functionally integrated gear stage for next-generation electric vehicles, produced by using Laser Beam Melting (LBM) and Fused Deposition Modeling (FDM). Two new design targets are addressed by our approach: Oil-free operation is achieved by innovative coating of gear teeth which enables almost maintenance-free operation. Furthermore, a higher damping of sound transmission from tooth mesh to bearings is implemented by an optimal wheel body geometry that is realized by a combination of printable carbon-containing polymers (flange) and steel (gear rim). The innovative approach is to extend components by areas that cannot be produced by milling and casting, e.g. complex structures, contour-following fluid-carrying cooling elements by means of LBM, thus creating a significant benefit compared to state-of-the-art gearboxes. Function integration made possible by additive manufacturing results in a very high component complexity. It is combined with gear grinding and final ta-C coatings ensuring maximum efficiency in dry operation, to achieve economically viable production processes. The increase in tooth mesh efficiency is achieved by optimization approaches in the design to minimize heat losses while at the same time maintaining highest possible strength and lowest noise emission.

关键词： Gears Wheels Production Three-dimensional printing Laser beams Coatings Next generation networking

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