December 2009

Machine Tool Virtual Model

MM (Modern Machinery) Science Journal, December 2009
J. Vesely, M. Sulitka
Research Center of Manufacturing Technology
CTU in Prague, Czech Republic

Machine tool development for high speed and highly precise cutting demands employment of advanced simulation techniques, which can enable already in the machine tool design phase to model the feed drive dynamic properties and feed drive control. The paper describes the current state of feed drive complex models development in the RCMT. Influence of an appropriate approach to machine frame structure modelling on the feed drive dynamic properties prediction is discussed together with the influence of the ball screw feed drive mechanical structure parameters. Shown are examples of complex models application in the tasks of machine tool development and optimization. Vision of the machine tool virtual models development aims at the possibility to simulate the cutting process with the employment of the Hardware in the Loop systems and cutting process model.

Keywords: Machine Tools, Virtual prototyping, Feed drive optimization, Feed drive dynamic properties, Feed drive complex modelling
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MM (Modern Machinery) Science Journal, December 2009
R. Halama1), M. Fusek1), J. Valíček2)
1) Department of Mechanics of Materials
VŠB-Technical University of Ostrava, Czech Republic,
2) Institute of Physics, VŠB-Technical University of Ostrava
Czech Republic

The paper deals with numerical and experimental solution of residual stresses, which occurs due to a contact loading. The first solved case corresponds to frictionless contact in an indent test accepted from literature. In the finite element analysis, three material options with isotropic, kinematic and combined hardening were tested. The model of Calloch and Marquis, which was implemented into the Ansys FE program by user subroutine, shows the best correlation with experiments. The experimental results were obtained by two experimental methods, namely by the Neutron diffraction method and by the Contour method, which is not well known in the Czech Republic. Hence, this paper includes also a brief description of the new destructive method. Both methods can lead to prediction of full field residual stresses distribution. Some difficulties from application of the contour method to own experiment in rolling contact fatigue domain are also discussed.

Keywords: residual stress, plasticity, contour method, FEM, rolling contact fatigue
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MM (Modern Machinery) Science Journal, December 2009
Zd. Pala, N. Ganev, K. Kolarik
Department of Solid State Engineering, Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague, Prague, Czech Republic

Macroscopic residual stresses on the surface and their depth distributions in steels ground in various cooling environments represent the central issue of this contribution. The specimens were manufactured from three ferrous materials – carbon steel C45, low carbon Mn-Cr steel 16MnCr5 and corrosion-resistant chromium steel M300, and consequently ground with face grinding machine and corundum wheel in three regimes of heat removal: ambient air, emulsion of water and synthetic fluid for grinding operations and cooling air from Ranque –Hilsch vortex tube. Methods of X-ray diffraction (XRD) analysis were applied for evaluation of anisotropic state of triaxial residual stress. Since the XRD is sensitive to surface layers of only a few micrometers in thickness, electro-chemical etching had to be employed in order to obtain gradients of chosen components of macroscopic residual stress tensor.

Keywords: grinding, cooling, residual stress, X-ray diffraction, electro-chemical polishing
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MM (Modern Machinery) Science Journal, December 2009
K. Kolarik1, N. Ganev1, Zd. Pala1, J. Barcal2 T. Bakalova3, M. Svanter4
1Department of Solid State Engineering
Faculty of Nuclear Sciences and Physical Engineering CTU in Prague
Prague, Czech Republic
2 Department of Manufacturing Technology
Faculty of Mechanical Engineering, CTU in Prague
Prague, Czech Republic
33 Department of Machining and Assembly
Faculty of Mechanical Engineering, TUL of Liberec
Liberec, Czech Republic
4 New Technologies Research Centre
Termomechanics of Technological Processes
Pilsen, Czech Republic

HSC (High Speed Cutting) and EDM (Electro Discharge Machining) belong to the progressive and harsh machining operations. They differ markedly in the manner of material removal and, consequently, in the process of a final surface formation. While HSC represents the so called chip machining, EDM embodies a utilization of controlled thermal material reduction. With respect to the usage of these technologies, tool steels K110 and W300 were chosen for the experiments. Samples made from both the materials were primarily subjected to either HSC or EDM and residual stresses were investigated by means of X-ray diffraction, Barkhausen noise, hole-drilling, and layer removal methods.

Keywords: X-ray diffraction, residual stress, high speed cutting, electro discharge machining
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