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Microstructuring of Surfaces by Two-stage Vibration-assisted Turning

Procedia CIRP 2014年 14卷 136-141页

作者： R. Zhang P. Steinert A. Schubert Technische Universität Chemnitz Faculty of Mechanical Engineering Professorship Micromanufacturing Technology 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

Microstructuring is one suitable method to improve the tribological properties of surfaces. It leads to a reduction in friction and wear, especially in highly loaded tribological contacts. There are several machining techniques to generate microstructures, such as laser beam removal, cold forming, etching or fly-cutting. This paper describes a new method to produce microstructured surfaces more economically, based on a two- staged vibration-assisted turning process. During the first step, a specific microstructure is realized by ultrasonic vibration assistance of the turning tool in the direction perpendicular to the workpiece surface. In the subsequent step, the peaks of the obtained microstructured surface are removed by precision turning without vibration. This results in a plateau-shaped and microdimpled surface. The two-staged vibration- assisted turning process offers the advantage that no additional process is required after finishing because the microstructuring process is already part of the finishing operation. The investigated process can easily be integrated into large batch production, e. g., for tribological optimization of powertrain components.

关键词： Surface microstucturing Vibration-assisted turning Tribology

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High Performance of Machining Processes by Applying Adaptronic Systems

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Procedia CIRP 2014年 14卷 500-505页

作者： W.-G. Drossel A. Bucht C. Hochmuth A. Schubert A. Stoll J. Schneider R. Schneider Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Technische Universität Chemnitz Institute for Machine Tools and Production Processes Reichenhainer Str.70 09126 Chemnitz Germany

Manufacturing processes are constantly facing the demand for higher efficiency regarding time, costs and resource consumption. In addition, challenges arise from the use of new materials and stricter requirements concerning the efficiency of the final product in use. Besides the economic perspective of realizing a highly efficient production and sustainable products, a new level of standards is set by politics and industry. To meet these demands, it may no longer suffice to improve processes by optimizing process parameters. Instead, advanced machine and tool concepts will be necessary and therefore have to be developed. An innovative approach to enhance the cutting process is the integration of adaptronic systems. This integration can happen at different levels, from no close loop control to using additional feed drives and in the cutting tool or in the machine. The paper presents examples from research at fraunhofer IWU for the application of adaptronic systems in machining processes, such as ultrasonic assisted machining, adaptronic form honing and adaptive spindle support for precision finishing of cylinder bores. Properties of the actuators and the adaptronic systems are described and the effects on both, the efficiency of the machining process and the final product performance, are discussed.

关键词： Adaptronic form honing Adaptive spindle support Ultrasonic assisted machining Hybrid processes

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CAD Kernel based Simulation of Milling Processes

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Procedia CIRP 2014年 17卷 710-715页

作者： Philipp Klimant Marco Witt Michael Kuhl Institute for Machine Tools and Production Processes Technische Universität Chemnitz eichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Reichenhainer Str. 88 09126 Chemnitz Germany

This paper describes a simulation method for NC programs. The simulation uses real axis values from a real CNC as a basis for the simulation of the generated NC program, respectively the milling strategy. To simulate the milling process by means of material removal at the virtual work piece a real CAD core was used. The CAD kernel based material removal simulation allows a close to reality simulation of the real executed NC program and enables a comparison between the simulated work piece geometry and the target CAD geometry directly in a CAD program.

关键词： CAD Kernel Simulation Milling Process

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Development of an optical measurement system for hip implant surgery to evaluate the leg length and the hip rotation center

Development of an optical measurement system for hip implant...

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Middle East Conference on Biomedical Engineering (MECBME)

作者： R. Grunert C. Kretzschmar C. Rotsch M. Werner T. Prietzel Medical Engineering Fraunhofer-Institute for Machine Tools and Forming Technology Dresden Germany Orthopedic Hospital University of Leipzig Leipzig Germany

The correct leg length and the position of the hip rotation center are the most important parameters for hip implant surgery. Until now there exist no suitable methods to measure it objectively. This paper describes an approach for determining leg length and hip rotation center with an optical measurement system for total hip replacement procedures. A software was programmed by the authors for this application implementing also commercial software solutions. The 3D models of the leg before and after the positioning of the hip implant were created with the Microsoft Kinect camera. Two scanned models of the leg were compared with each other. The difference between the point datasets on the screen is colored visualized and shall show the surgeon if the leg has the same length with the implant as before. During a feasibility study 30 leg models in different positions were compared to evaluate the accuracy, performance and usability of the software and the Kinect camera itself. The accuracy study shows that 96.4% of the 3D-model data points are within a range of 0-10mm. It can be recognized that the application of the Microsoft Kinect camera could be a suitable approach for determining leg length and hip rotation center in a cost-efficient and patient-friendly way.

关键词： Hip Iterative closest point algorithm Accuracy Cameras Length measurement Software Implants

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Structural Integration of PZT Fibers in Deep Drawn Sheet Metal for Material-integrated Sensing and Actuation

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Procedia technology 2014年 15卷 658-667页

作者： M. Müller B. Müller S. Hensel M. Nestler S.F. Jahn V. Wittstock A. Schubert W.-G. Drossel Professorship for Adaptronics and Lightweight Design in Production Technische Universität Chemnitz 09107 Chemnitz Germany Professorship Micromanufacturing Technology Technische Universität Chemnitz 09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Professorship Machine Tools and Forming Technology Technische Universität Chemnitz 09107 Chemnitz Germany

Today, adaptive sheet metal parts are manufactured by surface bonding of sensors and actuators on shaped structural parts. This paper presents a technology for direct structural integration of lead-zirconate-titanate (PZT) fibers in flat sheet metal and subsequent shaping. Microcavities are microformed into the surface of the metal sheet in which piezoceramic fibers are inserted and joined. After that, the composite is shaped by deep drawing into a complex 3D surface. The production technology is discussed in detail with regard to the limits of each process step. Functional shaped prototypes with ten interconnected parallel piezoceramic fibers were fabricated. The function as transducer and sensor for lamb waves is demonstrated and the degradation due to the shaping is compared for different parameters of the deep drawing process. The composite shapes are cups with a double curvature radius of 100 mm and 250 mm respectively. As a result, degradation of the piezoelectric function varies as a consequence of the process parameters. In the best case, a degradation of the transducer function of 33% was shown in the experiments. The cause of the decreased performance after shaping is discussed and explained by debonding mechanisms. Results of numerical simulations show good agreement with the experimental findings of the optimum process parameters.

关键词： Functional integration direct integration piezoceramic microforming microassembly deep drawing simulation function test sensor

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Influence of Alloying Elements and Extrusion Process Parameter on the Recrystallization Process of Mg-Zn alloys

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Materials Today: Proceedings 2015年 2卷 S19-S25页

作者： E. Meza-García J. Bohlen S. Yi D. Letzig V. Kräusel D. Landgrebe K.U. Kainer Technische Universitaet Chemnitz Institute for Machine Tools and Production Processes Professorship Forming and Joining D-09107 Chemnitz Germany. Magnesium Innovations Center MagIC Helmholtz-Zentrum Geesthacht Max-Plank-Str. 1 D-21502 Geesthacht Germany. Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 D-09126 Chemnitz Germany

In the present work, the influence of the additions of zinc, zirconium and cerium-rich mischmetal on the microstructural recrystallization development of magnesium were investigated. Grain size and chemical composition were the principal variables of the billets used for indirect extrusion experiments. Significant changes in the evolution of the dynamic recrystallization (DRX) process as a function of the alloying element contents and the process variables were observed. Microstructures and preferred orientation of crystallites were correlated in order to discuss the role of alloy composition on the DRX. This discussion was based on the macro-texture measurements and some EBSD measurements of selected samples.

关键词： Magnesium wrought alloys zinc zirconium rare earth elements indirect extrusion recrystallisation texture

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A Reconfigurable Tooling System for Producing Plastic Shields

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Procedia CIRP 2014年 17卷 853-858页

作者： Dominik Simon Lisa Kern Julia Wagner Gunther Reinhart Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Project Group Resource-efficient Mechatronic Processing Machines Beim Glaspalast 5 86153 Augsburg Germany Technische Universität München (TUM) Institute for Machine Tools and Industrial Management (iwb) Boltzmannstrasse 15 85748 Garching Germany

State of the art for producing 3-dimensional formed plastic shields is the use of mould blocks that are milled on machining centers. This paper describes the replacement of traditional mould blocks by a novel automated reusable mould and tooling system that produces good forming results at low investment costs. The reconfigurable tooling system replaces commonly used mould blocks. Two major issues will be addressed. The first aim is to identify principles for low tooling costs, while the second focuses on the improvement of a forming process suitable for the system so that this can be used for a broad range of products.

关键词： flexible forming reconfigurable tooling system thermoforming plastic shields

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Integration of vision/force robot control for transporting different shaped/colored objects from moving circular conveyor

Integration of vision/force robot control for transporting d...

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International Workshop on Robot Sensing (ROSE)

作者： Michael Jokesch Mohamad Bdiwi Jozef Suchý Robot Systems Chemnitz University of Technology Chemnitz Germany Tools and Forming Technology IWU Fraunhofer Institute for Machine Chemnitz Germany Technische Universitat Chemnitz Chemnitz Sachsen DE

This paper will propose algorithms for transporting different objects from moving circular conveyor with the help of vision/force robot control. Poses and speeds of the objects are calculated from sequential images captured by 3D-camera mounted on the hand of the robot. In the conveyor there are 4 slots which contain four differently formed and coloured objects. The cross sections of these objects are the square, the rectangle, the triangle and the circle. The required object will be segmented and then recognized with the help of fast image processing algorithm depending on its colour and shape. Furthermore, this paper will improve algorithm for grasping and pulling-out the required object from slot with tight clearance. For this task two different kinds of simple force control have been developed. The objects will be grasped by a 6-DoF robot with a primitive two-finger-gripper as end-effector. In the first experiment the proposed system will follow the required object until the movement of the conveyor stops. After that it will start to pull-out the object. In more complicated case, the robot will pull-out the object while the conveyor is moving. In other words, the movement of the robot will be synchronized with the movement of the object and it should grasp it at a convenient time and pose without any prior knowledge about its velocity. This paper will be supported with real experiments presenting promising results which illustrate the capability of grasping a stuck moving object with the help of vision/force robot control.

关键词： Force Grippers Trajectory Grasping Robot kinematics Cameras

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Closed loop control for shape memory alloy actuators

Closed loop control for shape memory alloy actuators

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IEEE SSD International Multi-Conference on Systems, Signals and Devices

作者： Christian Auerswald Björn Senf Jan Mehner Welf-Guntram Drossel Chair of Microsystems and Precision Engineering Technische Universität Chemnitz Chemnitz Germany Adaptronics and Acoustics Fraunhofer IWU Institute for Machine Tools and Forming Technology Chemnitz Germany

This paper describes design considerations of a control circuit for adaptive hybrid structures. These consist of a fiber-reinforced lightweight structure with a thermoplastic matrix and additional shape memory alloy wires, which can be used both as actuators and sensors. In order to use their properties, a control circuit able to heat the actuator wires and to measure their electrical resistance when used as a sensor is needed. In contrast to most references using expensive lab test equipment, a small sized, stand-alone control box is presented. It combines advantages of precision linear current sources for resistance measurement with high efficiency switch-mode converters delivering the wire heating current.

关键词： Heating Electrical resistance measurement Voltage measurement Resistance Optical fiber devices Matrix converters Magnetic properties

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Generic energy-enhancement module for consumption analysis of manufacturing processes in discrete event simulation 20

Generic energy-enhancement module for consumption analysis o...

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20th CIRP International Conference on Life Cycle Engineering, LCE 2013

作者： Stoldt, Johannes Schlegel, Andreas Franz, Enrico Langer, Tino Putz, Matthias Fraunhofer Institute Machine Tools and Forming Technology Chemnitz Germany

ISBN: (纸本)9789814451475

Customer demands for eco-friendly goods, energy supply bottlenecks or consumption/emission restrictions in many countries, as well as the current economic situation demand a conscious use of energy in industry. Manufacturers and suppliers need to increase efficiency of their products, processes and resources dramatically in order to reach agreed energy targets. To achieve substantial reductions it becomes necessary to establish predictive assessments of the energy demand for new production systems and whole manufacturing sites as standard operating procedures in systems engineering. This paper discusses a newly developed, generic energy-enhancement module, which renders resource consumption analyses within material flow simulation software possible.

关键词： Discrete event simulation

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