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Evaluation of thermo-energetic behavior for demand-oriented operating of machine tool cooling systems

Procedia Manufacturing 2018年 21卷 213-220页

作者： Joachim Regel Du Xu Michael Bräunig Volker Wittstock 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

In state of the art machine tools, structural thermal displacement is commonly reduced by cooling and tempering measures. The application of these measures frequently counteracts the original goal of energy efficiency. To design demand-oriented cooling systems, this paper presents a method to evaluate cooling measures and control parameters by means of a variance-based sensitivity analysis regarding the thermo-energetic efficiency. The evaluation is carried out by using the example of a machine bed made of high performance concrete. The integrated fluid-air cooling system with fan speed control and the bed structure are modelled by lumped elements. In addition to the PID-control of the cooling fluid temperature, the evaluation considers a two-position control of separately controllable cooling circuits and the influence of ambient temperature. The criteria to evaluate are temperature differences within the machine structure, the dissipated heat and their proportions to deployed electrical energy.

关键词： machine tool sensitivity analysis thermal measures cooling system energy efficiency simulation experiment thermal modeling

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Sensorless fault detection in linear axes with dynamic load profiles

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Procedia Manufacturing 2018年 19卷 66-73页

作者： M. Putz C. Trimborn C. Naumann J. Fischer M. Naumann L. Gebel Fraunhofer-Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Volkswagen AG Berliner Ring 2 38440 Wolfsburg Germany

Press lines are commonplace in the automotive industry. They typically use transfer systems to transport parts from one manufacturing stage to the next. Since these transfers are forced to endure great loads, both the gears and the shaft break fairly frequently and need to be replaced. Since every minute of downtime these maintenance tasks require costs manufacturers a lot of money, a condition monitoring system able to detect or predict damaged parts in linear drives would allow them to schedule maintenance so that downtime can be minimized and costs reduced. This paper presents a new method of fault detection for dynamic load profiles which is non-intrusive and requires no additional sensors. After a brief overview of the state of the art in fault detection and condition monitoring, the new method will be explained and demonstrated using measurement data from a press transfer.

关键词： Condition monitoring Servo system Motor current signature analysis

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Virtual Prototyping Technologies Enabling Resource-Efficient and Human-Centered Product Development

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Procedia Manufacturing 2018年 21卷 749-756页

作者： C. Allmacher M. Dudczig P. Klimant M. Putz 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

In modern production environments employees work progressively closer together with autonomous robots and vehicles. Besides the technical specifications, the development of these products focuses on the human-machine interaction. Within the federally funded Project FOLLOWme an automated guided vehicle (AGV) for intralogistics that follows and interacts with the user is developed using virtual reality based prototypes. The benefits in comparison to using only physical prototypes are on the one hand specific user feedback regarding ergonomics and trust. On the other hand the validation of navigation and collision avoidance algorithms and optimization of technical parameters is achieved considering complex environmental conditions. This paper focuses on the latter in detail and deals with the optimization of a fuzzy logic controller using the game engine Unity3D to create the required virtual setup. This approach saves valuable time at early project stages and allows the optimization of a larger number of parameters compared to just physical tests. Furthermore it reduces resources like occupied physical infrastructure and improves the comprehension by using virtual reality.

关键词： Resource Efficiency Human Factors Virtual Prototype Automated Guided Vehicle Obstacle Avoidance Fuzzy Logic Controller Unity3D

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The Effect of Torsional Vibrations on Metal Cutting Dynamics

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Procedia CIRP 2018年 77卷 461-464页

作者： Andreas Otto Martin Kolouch Günter Radons Institute of Physics Chemnitz University of Technology 09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany

The effect of torsional vibrations on the dynamics of metal cutting processes is studied. An extended dynamic process model is presented, where the spindle angle and the time delay are dynamic variables resulting in delay differential equations with state-dependent delay. Stability lobes are calculated based on the new extended process model and compared with results from the classical chatter theory with constant spindle speed and delay. For an ideal symmetric tool, stable cutting is characterized by a periodic spindle speed but still a constant delay. In this case, the main difference between the new extended and the classical model is a different periodic solution to periodic torsional tool displacements, which results only in slight modifications of the stability lobes. However, the new theory shows that it is important to consider tool asymmetries (e.g. runout), because this would result in periodically varying delays during stable cutting and larger stability changes due to torsional vibrations.

关键词： Metal Cutting Sawing Chatter Vibrations Stability State-dependent delay

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Conserving Resources in Production - Breaking New Ground

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Procedia Manufacturing 2017年 8卷 619-626页

作者： Landgrebe, D. Kräusel, V. Bergmann, M. Werner, M. Rautenstrauch, A. Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Straße 88 Chemnitz 09126 Germany Machine Tools and Forming Technology Technische Universität Chemnitz Reichenhainer Straße 70 Chemnitz 09126 Germany

Many approaches focus on more efficient production processes, on avoiding waste and scrap and on more efficient use/operation of products within one life cycle, i.e. from raw materials to the end of use. All these approaches share the goal of an increase in resource efficiency. In contrast, the reProd® approach is characterized by a comprehensive view of cycles. By shortening the cycle process, a huge potential can be opened up for metal products regarding a reduction of energy requirements and CO₂ emissions. Approx. 70% to 90% of the energy requirements and also of the greenhouse gas emissions are necessary for melting the metals and for the first processing stage. If secondary semi-finished products are obtained from used goods, energy-intensive processes are eliminated. Thus a decisive contribution for the energy turnaround and for protecting climate and environment lies in “non-destructive recycling” and “re-use without melting” © 2017

关键词： material cycle recycling economie

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Microstructure of Inconel 718 parts with constant mass energy input manufactured with direct energy deposition

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Procedia Manufacturing 2019年 36卷 256-266页

作者： Torsten Petrat Christian Brunner-Schwer Benjamin Graf Michael Rethmeier Fraunhofer Institut for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Federal Institute for Materials Research and Testing Unter den Eichen 87 12205 Berlin Germany Technical University Berlin Institute of Machine Tools and Factory Management Pascalstraße 8-9 10587 Berlin Germany

The laser-based direct energy deposition (DED) as a technology for additive manufacturing allows the production of near net shape components. Industrial applications require a stable process to ensure reproducible quality. Instabilities in the manufacturing process can lead to faulty components which do not meet the required properties. The DED process is adjusted by various parameters such as laser power, velocity, powder mass flow and spot diameter, which interact with each other. A frequently used comparative parameter in welding is the energy per unit length and is calculated from the laser power and the velocity in laser welding. The powder per unit length comparative parameter in the DED process has also be considered, because this filler material absorbs energy in addition to the base material. This paper deals with the influence of mass energy as a comparative parameter for determining the properties of additively manufactured parts. The same energy per unit length of 60 J/mm as well as the same powder per unit length of 7.2 mg/mm can be adjusted with different parameter sets. The energy per unit length and the powder per unit length determine the mass energy. The laser power is varied within the experiments between 400 W and 900 W. Energy per unit length and powder per unit length are kept constant by adjusting velocity and powder mass flow. Using the example of Inconel 718, experiments are carried out with the determined parameter sets. In a first step, individual tracks are produced and analyzed by means of micro section. The geometry of the tracks shows differences in height and width. In addition, the increasing laser power leads to a higher dilution of the base material. To determine the suitability of the parameters for additive manufacturing use, the individual tracks are used to build up parts with a square base area of 20×20 mm². An investigation by Archimedean principle shows a higher porosity with lower laser power. By further analysis of the mic

关键词： direct energy deposition porosity Inconel 718 additive manufacturing laser metal deposition

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Equivalence assessment method for the resource efficiency of equipment, technologies and production systems

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Procedia Manufacturing 2018年 21卷 525-532页

作者： A.P. Kuznetsov H.-J. Koriath A.V. Kalyashina T. Langer Moscow State University of Technology “STANKIN” 127055 Moscow Russia Fraunhofer Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany Kazan National Research Technical University Kazan Russia

The paper analyses different assessment methods for the overall equipment effectiveness (OEE), energy efficiency and productivity of equipment and production systems. The proposed model and systematic assessment approach define the total and relative resource efficiency of equipment, technologies and production systems in the form of material, energy and information efficiency. This common resource efficiency assessment method is based on the physical and mathematical equivalence of efficiency indicators including probable events for resource usability. Three typical relations, determining any kind of efficiency, are obtained from those equivalents. Examples for resource efficiency assessment types are energy efficiency, productivity and accuracy. Integrated evaluation indicators for a comparative benchmarking of equipment, technologies and production systems are provided based on the equivalence assessment method and the proposed three typical relations. This method is also applicable to process chains.

关键词： equipment resource efficiency technology production system

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A Virtual Hip Replacement Surgery Simulator with Realistic Haptic Feedback

A Virtual Hip Replacement Surgery Simulator with Realistic H...

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IEEE Annual International Symposium Virtual Reality

作者： Maximilian Kaluschke René Weller Gabriel Zachmann Luigi Pelliccia Mario Lorenz Philipp Klimant Sebastian Knopp Johannes P. G. Atze Falk Möckel University of Bremen Computer Graphics and Virtual Reality IWP Chemnitz University of Technology Fraunhofer Institute for Machine Tools and Forming Technology IWU FAKT Software

We present the first VR training simulator for hip replacement surgeries. We solved the main challenges of this task - high and stable forces during the milling process while simultaneously a very sensitive feedback is required - by using an industrial robot for the force output and the development of a novel massively parallel haptic rendering algorithm with support for material removal.

关键词： Haptic interfaces Surgery Hip Rendering (computer graphics) Training Milling Robots

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Active flow control in wind turbines - Integration technologies and assessment of economic effects 12

Active flow control in wind turbines - Integration technolog...

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Smart Systems Integration 2018 - 12th International Conference and Exhibition on Integration Issues of Miniaturized Systems

作者： Schüller, Martin Lipowski, Mathias Weigel, Perez Symmank, Christina Meynerts, Lilly Walther, Marco Dziuba, Franz Otto, Thomas Götze, Uwe Kroll, Lothar Department Multi Device Integration Fraunhofer Institute for Electronic Nano Systems Chemnitz Germany Management Accounting and Control Chemnitz University of Technology Chemnitz Germany Department of Lightweight Structures and Polymer Technology Chemnitz University of Technology Chemnitz Germany Forschungszentrum Systeme und Technologien für textile Strukturen STEX Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Germany Center for Micro Technologies Chemnitz University of Technology Chemnitz Germany

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Piezoceramics in sheet-metal compounds for icing detection 8

Piezoceramics in sheet-metal compounds for icing detection

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8th ECCOMAS Thematic Conference on Smart Structures and Materials, SMART 2017 and 6th International Conference on Smart Materials and Nanotechnology in Engineering, SMN 2017

作者： Drossel, W.-G. Nestler, M. Mäder, T. Schönherr, J. Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9788494690938

Icing detection and de-icing techniques play an important role to assure a safe operation of airplanes and wind turbines [1, 2]. Integration of piezoceramics in structural parts allow for additional functionalities like health monitoring, impact detection and even to solve icing problems. The paper deals with innovative sheet-metal compounds, consisting of a piezomodule in a layer of adhesive embedded between two aluminum sheets. An airfoil demonstrator structure with integrated piezomodules is used for icing detection. A special production and forming technology was presented in earlier studies, where forming takes place in a viscous condition of adhesive. This concept allows for a forming of brittle piezoceramic fibers inside the compound. This demonstrator structure was built with this production technology. The integrated sensor is used for a detection of additional local masses. Aim is the implementation for aerodynamic icing detection and a vibration assisted de-icing. Within the paper preliminary tests for an icing detection are described. Therefore impedance and loss angle of an integrated piezomodule are measured for a broad frequency range under variation of additional masses and temperature. Icing was performed inside a cold chamber at -40 °C. It is shown that the impedance is significantly influenced by additional masses at room temperature, by a reduction of temperature without additional masses and by additional masses (ice) at reduced temperatures. The results imply that the assumptions are correct and the continuative investigations are worthwhile to potentially develop an icing detection technology. © 2017 International Center for Numerical Methods in Engineering. All rights reserved.

关键词： Adhesives

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