October 2009

Drive Based Vibration Reduction for Production Machines

MM (Modern Machinery) Science Journal, October 2009
A. Dietmair, A. Verl
Institute for Control Engineering of Machine Tools and Manufacturing Units (ISW), Universität Stuttgart, Germany

Machine vibrations constitute a persistent challenge for high performance and high precision production machines that show resonant behaviour at some frequencies. Most remedies require additional actuators or precise knowledge of the dynamic behaviour of the machines under consideration. To overcome this limitation, we present several techniques that use the feed drives to dampen vibrations or avoid excitation and are applicable with minimal pre-knowledge. Moreover, we introduce an approach to treat machines with resonant frequencies that change with the tool centre point position.

Keywords: Machine Vibration, Active Damping, Control Algorithms
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Automatized system of measuring and regulation in turning operations

MM (Modern Machinery) Science Journal, October 2009
R. Kreheľ
Technical University of Kosice with a seat in Presov Slovak Republic

A novel approach to the simulation of the dimensional wear of cutting tools with a subsequent element of correction in limit boundaries of parametrically determined optimal shifts is presented and discussed. Described in details is, however, only one aspect belonging to the polynomial transform of experimentally found discrete values of the cutting point positions to a continuous functional form, compatible with used SW. Special attention is paid to the proposal of the simulation scheme working with the mathematical model in the simulation environment with particular values of the given simulation parameters.

Keywords: Cutting, sensor, workpiece, component, optical, scanning, measurement
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Virtual animation for checking interference of globoidal cam

MM (Modern Machinery) Science Journal, October 2009
Nguyen Van Tuong1, Premysl Pokorny2
1Department of Manufacturing Engineering, University of Nha Trang, Nha Trang, Vietnam 2Department of Manufacturing Systems, Technical University of Liberec, Liberec, Czech Republic

This article proposes some important tasks which are necessary in the modeling procedure of globoidal cams. These tasks are modeling and virtual animation of the globoidal cam mechanism for checking interference between components of the system. The acceptable cam is the one that has no interference between the cam and its rollers assuming that the clearance between cam surfaces and roller is zero or very small. Techniques of animation and checking interference of globoidal cam mechanism are performed in Pro/ENGINEER Wildfire 2.0.

Keywords: modeling, animation, interference, globoidal cam, follower
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Comparison of Performance of Austrian made Si3N4 – Nitride Ceramic Tools Used to Machine Grey Cast Iron Work-piece Materials

MM (Modern Machinery) Science Journal, October 2009
J. Kovalcík, J. Cuban
Department of Machining and Assembly, Technical University of Liberec, Czech Republic

This article presents comparisons of cutting performance of Austrian made – Si3N4 nitride ceramic – inserts used in machining a Type 422425 grey cast iron work-piece materials. Three commercial ceramic inserts Type FMG121C, FMG122C, and FMG134C were tested. Experiments were focused on tool life tests. A comparison approach involved exponents of Taylor’s type equations over an optimized cutting tool interval i.e. one constant depth of cut of 1mm, one constant feed rate of 0.2 mm/rev and the three cutting speeds 250, 320 and 380 m/min. Results were obtained from linear regression. Also conducted was an evaluation of intervals of reliability as well as corresponding standard deviations for each regression coefficient in experimental Taylor’s equations. The experiments allowed to compare, from statistical perspectives, at a 95 and greater confidence level, the trends and quantities of experimental cutting inserts. The results showed that a Type FMG122C ceramic insert had the most superior performance compared to other two types of experimental ceramic inserts investigated in this study.

Keywords: Metal machining, ceramic inserts, grey cast iron, work-piece material, tool life, Taylor’s logT-log v regression lines, trends and quantities, statistical anylyses
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