This paper presents a tool wear monitoring strategy based on a large number of signal features in the rough turning of Inconel 625. Signal features (SFs) were extracted from time domain signals as well as from frequency domain transforms and their wavelet coefficients (time-frequency domain). All of them were automatically evaluated regarding their relevancy for tool wear monitoring based on a determination coefficient between the feature and its low-pass-filtered course as well as the repeatability. The selected SFs were used for tool wear estimation. The accuracy of this estimation was then used to evaluate the sensor and signal usability.
Nickel-based superalloys are widely used in the aircraft industry since they are exceptionally thermal resistant, retaining their mechanical properties at temperatures of up to 700 • C. On the other hand, since they are very difficult to machine, tool life is typically short and can finish abruptly. As catastrophic tool failure can destroy an expensive workpiece, automatic tool condition monitoring (TCM) has become particularly critical. This paper presents an application of the wavelet packet transform (WPT) for extracting useful TCM features from the cutting forces and acoustic emission (AE) signals during rough turning of Inconel 625. New, improved methods of signal feature (SF) relevancy evaluation were proposed based on determination and correlation coefficients. Out of several SFs calculated from bandpass signals, the most useful for TCM were automatically selected. The selected features were used for tool condition monitoring.
This paper presents assessment of technological usefulness of panel production line in prefabrication process of large ship hull sections, in which special attention is paid to producibility of welding operations. Basing on the assessment these authors worked out hierarchy of analyzed sequences of welding technological processes as well as production line stands used for the processes. The assessment was performed on the basis of analysis of a concept of panel production line based on real production lines functioning in shipbuilding industry, as well as technical documentation of typical hull sections of a multi-purpose ferry. The presented analysis took into account impact of technological - constructional parameters onto producibility of welding process of prefabricated sections. Among these parameters the following were numbered: mass of the sections and number of their elements, total length of welds, labour consumption, material consumption as well as linear heat input in welding operations. On the basis of the achieved results, places which worsen effectiveness of production line operation were identified, as a result it was possible to formulate proposals for modernization of flow prefabrication line for hull sections.
StreszczenieW artykule przedstawiono wyniki badań eksperymentalnych czterech postaci odkształceń spawalniczych panelu I-core. Panel ten jest częścią węzła hybrydowego. Badania przeprowadzono wg zasad teorii planowania eksperymentu w warunkach laboratoryjnych, zbliżonych do warunków panujących w przemyśle. Przedstawiona analiza postaci deformacyjnych uwzględnia parametry technologiczno-konstrukcyjne wpływające na przydatność montażową wielkogabarytowej konstrukcji stalowej. Omówiona metoda oceny wyników eksperymentalnych umożliwia wykorzystanie wzorów aproksymacyjnych w celu prognozowania analizowanych postaci odkształceń w konstrukcjach wielkogabarytowych.
AbstractThe paper presents the results of experimental research on four types of welding distortions of I-core panel. This panel is a part of a hybrid node. The research has been carried out according to design of experiment technique in laboratory conditions near-real-life production conditions. The presented analysis of deformation picture accounts for technological-constructional parameters influencing the suitability for assembly of large-size steel construction. The presented appraisal method used for experiment results features implementation of approximation formulas in order to predict analysed types of distortions in large-size constructions. Fig. 1. Hybrid node [2]
Rys. 1. Węzeł hybrydowy [2]
The paper presents the results of experimental studies on distortion of the fixed plate edge due to formation of a butt joint. This is a hidden form of weld distortion present in structural nodes and identified at the ship hull pre-fabrication stages. The investigations were performed according to a design of experiment (DoE) approach in laboratory conditions resembling those encountered in the shipbuilding industry. The presented analysis includes the technological–construction parameters influencing the evaluated distortion shape. The implemented method of experimental results evaluation allows the utilisation of the approximation dependence to predict the fixed plate edge distortion in large-scale steel structures.
The article characterises the sea-going vessel hull assembly processes and then reviews the existing assembly methods of mechanisms and welded ship structures. Classification of these methods is done with respect to selected criteria of their applicability to hull assembly. Selected methods are used for calculations performed on a model structure and exemplary database. The analysed aspects include the performance of calculation algorithms and the quality of the obtained solutions. Particular attention is paid to the need for reduction of experts’ participation in the planning process due to strong search space explosion effect. The performed analyses have enabled the authors to formulate assumptions for models which would be applicable in real assembly planning in shipyards, as well as to indicate areas of further research which would make it possible to better consider the specificity of production of large-size welded structures.
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