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  • Author: Paweł Twardowski x
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Paweł Twardowski

Surface Roughness Analysis in Milling of Tungsten Carbide with CBN Cutters

In this paper, an experimental surface roughness analysis in milling of tungsten carbide using a monolithic torus cubic boron nitride (CBN) tool is presented. The tungsten carbide was received using direct laser deposition technology (DLD). The depth of cut (ap), feed per tooth (fz) and tool wear (VBc) influence on surface roughness parameters (Ra, Rz) were investigated. The cutting forces and accelerations of vibrations were measured in order to estimate their quantitative influence on Ra and Rz parameters. The surface roughness analysis, from the point of view of milling dynamics was carried out. The dominative factor in the research was not feed per tooth fz (according to a theoretical model) but dynamical phenomena and feed per revolution f connected with them.

Open access

Paweł Lisiak, Izabela Rojek and Paweł Twardowski

Abstract

The article describes a method of evaluating the reliability of groove turning for piston rings in combustion engines. Parameters representing the roughness of a machined surface, Ra and Rz, were selected for use in evaluation. At present, evaluation of surface roughness is performed manually by operators and recorded on measurement sheets. The authors studied a method for evaluation of the surface roughness parameters Ra and Rz using multi-layered perceptron with error back-propagation (MLP) and Kohonen neural networks. Many neural network models were developed, and the best of them were chosen on the basis of the effectiveness of measurement evaluation. Experiments were carried out on real data from a production company, obtained from several machine tools. In this way it becomes possible to assess machines in terms of the reliability evaluation of turning.

Open access

Szymon Wojciechowski, Paweł Twardowski and Michał Wieczorowski

Abstract

In this paper, an analysis of various factors affecting machined surface texture is presented. The investigation was focused on ball end mill inclination against the work piece (defined by surface inclination angle a. Surface roughness was investigated in a 3D array, and measurements were conducted parallel to the feed motion direction. The analysis of machined surface irregularities as a function of frequency (wavelength A), on the basis of the Power Density Spectrum - PDS was also carried out. This kind of analysis is aimed at valuation of primary factors influencing surface roughness generation as well as its randomness. Subsequently, a surface roughness model including cutter displacements was developed. It was found that plain cutting with ball end mill (surface inclination angle a= 0°) is unfavorable from the point of view of surface roughness, because in cutter’s axis the cutting speed vc ~ 0 m/min. This means that a cutting process does not occur, whereas on the machined surface some characteristics marks can be found. These marks do not appear in case of a* 0°, because the cutting speed vc * 0 on the fill I length of the active cutting edge and as a result, the machined surface texture is more homogenous. Surface roughness parameters determined on the basis of the model including cutter displacements are closer to experimental data for cases with inclination angles a* 0°, in comparison with those determined for plain cutting (a= 0°). It is probably caused by higher contribution in surface irregularities generation of plastic and elastic deformations cumulated near the cutter’s free end than kinematic and geometric parameters, as well as cutter displacements.

Open access

Agata Felusiak and Paweł Twardowski

Abstract

The present paper presents comparative results of the forecasting of a cutting tool wear with the application of different methods of diagnostic deduction based on the measurement of cutting force components. The research was carried out during the milling of the Duralcan F3S.10S aluminum-ceramic composite. Prediction of the toolwear was based on one variable, two variables regression Multilayer Perceptron(MLP)and Radial Basis Function(RBF)neural networks. Forecasting the condition of the cutting tool on the basis of cutting forces has yielded very satisfactory results.

Open access

Martyna Wiciak, Paweł Twardowski and Szymon Wojciechowski

Abstract

In this paper, the problem of tool wear prediction during milling of hard-to-cut metal matrix composite Duralcan™ was presented. The conducted research involved the measurements of acceleration of vibrations during milling with constant cutting conditions, and evaluation of the flank wear. Subsequently, the analysis of vibrations in time and frequency domain, as well as the correlation of the obtained measures with the tool wear values were conducted. The validation of tool wear diagnosis in relation to selected diagnostic measures was carried out with the use of one variable and two variables regression models, as well as with the application of artificial neural networks (ANN). The comparative analysis of the obtained results enable.

Open access

Jacek P. Twardowski, Paweł K. Bereś, Michał Hurej, Zdzisław Klukowski, Zbigniew T. Dąbrowski, Sławomir Sowa and Roman Warzecha

Abstract

In the southern part of Poland, ground beetle fauna was studied in the first large-scale Bt maize experiment. The aim of this study was to determine the long term impact of the Bt maize cultivar in comparison to conventional plants, on selected non-target arthropods. The DKC 3421 YG cultivar (Bt maize) and the respective isogenic non-Bt varieties (DKC 3420) were cultivated at two locations: (a) Budziszów near Wrocław and in Głuchów near Rzeszów in the south-eastern region of Poland, in the 2008-2010 growing seasons. For comparative analysis, two additional non-Bt cultivars sprayed with a lambda-cyhalotrine insecticide were also included. To monitor population density of surface-active invertebrates of the Carabidae family, eighty pitfall traps were used at each location. The average number of ground beetle populations in the Bt-maize cultivar DKC 3421 YG did not significantly differ from the number of beetles in the conventional ones. Significant differences between the number of beetles occurred on individual dates only. Usually, these differences related to the considerably smaller total number of beetles in the whole replication. Probably, the variation in the number of beetles was caused by climatic factors or the terrain layout, therefore it cannot be related to the cultivar effect.