July 2012

These papers were presented at 6th International Conference ERIN 2012, Prague

MULTIPARAMETRIC ANALYSIS OF SURFACE INTEGRITY AFTER TURNING THROUGH BARKHAUSEN NOISE IN RELATION TO TOOL WEAR

MM (Modern Machinery) Science Journal, July 2012
Jaroslav Dubec, Miroslav Neslusan
University of Zilina, Faculty of Mechanical Engineering, Department of Machining and Manufacturing Engineering, Zilina, Slovakia
Abstract

This paper deals with application of micromagnetic inspection of surface integrity after turning bearing steel 100Cr6 in dependence on increasing tool wear. This paper indicates influence of tool wear on the selected parameters of Barkhausen noise (RMS value, peak position). The analysis also contains measurement of residual stresses carried out by mechanical method and also analysis of microstructure modifications. The results of experiments show that RMS values of Barkhausen noise decreases with the tool wear as a results of increasing compressive stresses formation in the near surface layers. Moreover the structure transformation occurs in these layers for higher values of flank wear VB.

Keywords: Barkhausen noise, tool wear, residual stress
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STUDY OF AlSi10Mg ALLOY STRUCTURES AFTER MODIFICATION BY VARIOUS Sr AGENTS

MM (Modern Machinery) Science Journal, July 2012
Barbora Bryksi Stunova
Czech Technical University in Prague, Faculty of Mechanical Engineering, Department of Manufacturing Technology, Prague, Czech Republic
Abstract

The goal of the paper was to observe structures of alloy AlSi10Mg, which was modified by strontium in amount of 400 ppm. It is widely known the influence of eutectic silicon, recent works describe also the influence on the morphology intermetallic phases, such as iron, manganese or copper containing phases. Present work focuses also to phases containing magnesium. The effect of strontium on the structure defects, namely cavities, is also observed. It has been proven that strontium affects the morphology of the phases containing iron, manganese and magnesium, in particular β-phase Al5FeSi, Al15(FeMn)3Si2, FeMg3Si6Al8 and Mg2Si. Findings of other authors were also confirmed, that strontium negatively affects the level of gas porosity and distribution of shrinkages.

Keywords: Aluminum Alloys, Modification, Strontium, Structure, Intermetallic Phases, Structure Defects
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EVALUATION OF MODERN POWER SOURCE FOR GMAW WELDING EQUIPPED WITH ADVANCED ARC CONTROL

MM (Modern Machinery) Science Journal, July 2012
L. Kolarik1, M. Kolarikova1, K. Kovanda1, M. Pantucek2, P. Vondrous1
1 CTU in Prague, Faculty of Mechanical Engineering, Department of Manufacturing Technology, Technicka 4, Prague, CR
2 Migatronic CZ, a. s., Tolstého 451, Teplice, CR
Abstract

Modern welding power sources are equipped with special functions of arc control. These functions measure and adjust welding parameters during welding with minimum time delay so that the right parameters are set. At the Laboratory of welding technologies of CTU in Prague we have used modern welding source by Migatronic – Sigma Galaxy equipped with functions Intelligent Arc Control and Sequence Repeat. According to manufacturer these functions significantly improve welding process by stabilizing arc. This leads to lower heat input, deformation and improves weld quality. Single V butt welds were done on S275J2 of 10 mm thickness (2 weld layers: root + capping layer) in PF and PG positions. Also we have welded thin sheets with uneven root gap in PG position. Welding current, voltage was monitored by Welding Information System and compared with standard short arc GMAW welding. Results have shown that these “intelligent” functions offer significant advantages for welding of steels, especially in vertical positions, for welding of thin sheets, because they stabilize arc, lower heat input and thus improveweld metal control.

Keywords: Welding, GMAW, IAC, Sequence Repeat, Short Arc, Heat Input, Arc Control
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THE INFLUENCE OF HOLDING PRESSURE ON POWDER DISTRIBUTION IN PIM TECHNOLOGY

MM (Modern Machinery) Science Journal, July 2012
Pavel Petera
Technical University of Liberec, Faculty of Mechanical Engineering, Department of Engineering Technology, Liberec, Czech Republic
Abstract

The powder injection molding technology (PIM) is very sensitive process where the resulting quality of the part is defined by quality reached in each step of the whole process. This quality of the part is then usually possible to see first at the end of the process while the fault could occur already at the beginning, often during injection-molding. Therefore is necessary to find the way how to evaluate the injection-molding process and discover the fault earlier. Very often cause of the defects is the “phase separation” (inhomogeneity in powder distribution), which occurs during injection-molding and can be also influenced by the holding pressure. This paper is then focused on evaluation of the powder distribution in the “green part” stage with the new method based on density measuring. Measurements were done with using different values of holding pressure.

Keywords: PIM, CIM, Holding pressure, Phase separation, Green part
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IMPACT OF WATER REMAINS ON A HOT ROLLED PLATE AFTER COOLING

MM (Modern Machinery) Science Journal, July 2012
Radek Zahradnik
Heat Transfer and Fluid Flow Laboratory, Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic
Abstract

In situations when a sheet metal plate with large dimensions is rolled, the water remains from cooling can be observed on the top site of the plate. This paper is focused on the deformations of the hot rolled sheet metal plate which are caused by the water remains after cooling. A transient finite element simulation was used to describe a shape deformations of a metal sheet cross profile. The finite element model is fully parametric for easy simulation of multiple cases. The results from previous work were used for boundary conditions. The effect of gravitation was observed. The paper should provide an information if it is necessary to install blowing system in rolling process.

Keywords: water remains, FEA, simulation, hot plate, rolling, ANSYS
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