Now showing 1 - 9 of 9
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Measurement of tool temperatures in the tool-chip contact region by embedded thin film thermocouples

2010 , Kurz, M. , Geisert, C. , Oberschmidt, D. , Werschmoeller, D. , Uhlmann, E.

Monitoring and controlling thermo-mechanical parameters in the tooling material are imperative for improving the fundamental process understanding, assuring the reliability and meeting the desired workpiece quality of material removal processes. Polycrystalline cubic boron nitride (PCBN) tools are being used heavily in machining of low carbon steel and superalloys. These processes are very sensitive to variation in local machining conditions and lack a thorough understanding of fundamental thermo-mechanical phenomena. Existing sensors to monitor machining temperatures are not suitable for process control as they are either destructively embedded and/or don't possess the necessary spatial and temporal resolution. This paper presents an approach for assessing temperature data from the close vicinity of the tool cutting edge. For this purpose an array of 9 micro thin film thermocouple sensors, fabricated using standard microfabrication methods, has been embedded into PCBN using a modified diffusion bonding technique. Experiments were performed for assessing tool temperatures under the rake face of the tool and correlating these measurements to cutting force and vibration signatures.

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Ultra precision machine-integrated approach to measuring aspheres interferometrically

2008 , Uhlmann, E. , Kurz, M. , Bosse, M. , Neubert, R. , Bluemel, T. , Oberschmidt, D.

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Hochpräzise Werkzeug- und Werkstückvermessung - Kompensieren heißt, Fehler vermeiden

2007 , Hohwieler, E. , Kurz, M. , Essmann, J. , Oberschmidt, D.

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Machine-integrated measurement of specular free-formed surfaces using phase-measuring deflectometry

2009 , Richter, C. , Kurz, M. , Knauer, M.C. , Faber, C. , Olesch, E. , Häusler, G. , Oberschmidt, D. , Eßmann, J. , Uhlmann, E.

The authors present first results of a project with the long-term goal of performing optical measurements of ultra precision turned objects within the turning machine. Whereas ultra precision turning machines facilitate the manufacturing of optical free-formed parts, the task of measuring these objects is not yet solved satisfactorily. Moreover, an optical measurement within the machine would be of great advantage concerning a possible feedback to the turning process. Phase-measuring deflectometry has the potential to solve these tasks, but the system has to be adapted to provide the necessary dynamic range and to cope with the limited installation space within the system. We present measuring results of ultra precise turned parts manufactured on a 5-axis ultra precision machine. The surface of these objects displays a local slope up to 30. Furthermore, the potential for future integration of such a measurement system into an ultra precision lathe is demonstrated.

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Ultra precision machine integrated measurement of spheres and aspheres with a twyman-green interferometer

2008 , Uhlmann, E. , Kurz, M. , Bluemel, T. , Neubert, R. , Oberschmidt, D.

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Ultraprecision turning with binderless CBN

2006 , Oberschmidt, D. , Kurz, M.

Ultraprecision machining of steel with geometrically defined diamond cutting edge is not yet a stable industrial process. Therefore the optical surface quality corresponding to the optical function on the final product is achieved by polishing, classically. Unfortunately, the form accuracy of the work piece is affected by polishing processes. Successful ultraprecision facing experiments of fully heat-treated steel 40CrMnMoS8.6 has been made with binderless cBN as cutting material. Results of roughness values Ra < 35 nm and peak to valley of P-V < 200 nm were achieved. Removal rate is Q > 0,1 mm(exp 3)/s and the tool total path is about W(ind Ra) = 80 m. The generated surfaces show a homogeneous structure. Tools can be evaluated regarding geometrical characteristics and abrasion. Experiments show that the cutting material binderless cBN is of high potential regarding the machining of steel for moulds and dies. Despite the achieved roughness, the obtained surfaces are not of optical quality. This is documented by a Ra/PV ratio of about 1/7. And despite the homogeneity, the surface is refractive and therefore appears rough. In further research activities, particularly the preparation of the cutting edge has to be scrutinized.

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Taktiles Messen optischer Funktionsflächen

2008 , Kurz, M. , Eßmann, J. , Oberschmidt, D.

Am Produktionstechnischen Zentrum Berlin (PTZ) wurde jetzt untersucht, ob ein neues TAKTILES SENSORKONZEPT mit hoher Messgenauigkeit und geringen Antastkräften - integriert in ein modernes KMG - optische Funktionsflächen aus der Ultrapräzisionsbearbeitung zerstörungsfrei messen kann.

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Kompensieren heißt Fehler vermeiden

2007 , Hohwieler, E. , Kurz, M. , Essmann, J. , Oberschmidt, D.

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A new approach to the measurment of free form surfaces for micro optical applications

2006 , Uhlmann, E. , Kurz, M. , Oberschmidt, D. , Blümel, T. , Kafka, R. , Osten, S. , Krüger, S.