Praca przedstawia zagadnienie dotyczące pomiaru i analizy zużycia energii w trakcie cyklu wiercenia termicznego. Przedstawiono oparte na tokarce CNC stanowisko badawcze, którego elementem wyposażenia był eksperymentalny układ poboru energii oparty o licznik energii elektrycznej oraz siłomierz. Zastosowane urządzenia pomiarowe pozwalały na rejestrację obciążenia sieci energetycznej, obciążenia napędów obrabiarki, siłę osiową, moment hamujący wiertło, aktualne obroty wrzeciona obrabiarki, pozycję wiertła względem obrabianego materiału i wartości rejestrów parametrów pomocniczych w strategii adaptacyjnego sterowania posuwem. Rozważano dwa przypadki cyklu wiercenia: wykonanie pojedynczego otworu oraz wykonanie szeregu otworów w jednym cyklu. Testowano pięć strategii sterowania posuwem w trakcie cyklu wiercenia, w tym adaptacyjne sterowanie posuwem i rekurencyjną metodę optymalizacji posuwu. Dla porównania wykonano także otwory tradycyjnymi wiertłami krętymi HSS. Na podstawie uzyskanych rezultatów badań można stwierdzić, że metoda wiercenia ciernego może być zaliczona do energooszczędnych metod wykonywania otworów w elementach cienkościennych.
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The work presents the issue of measuring and analyzing energy consumption during a thermal drilling cycle. A research stand based on a CNC lathe was presented, the equipment of which was an experimental energy consumption system based on an electricity meter and a force gauge. The measuring devices used allowed for recording the load on the power grid, the load on the machine tool drives, the axial force, the drill braking torque, the current rotation of the machine tool spindle, the position of the drill in relation to the workpiece and the values of auxiliary parameter registers in the strategy of adaptive feed control. Two cases of a drilling cycle were considered: making a single hole and making a series of holes in one cycle. Five feed control strategies were tested during the drilling cycle, including adaptive feed control and a recursive feed optimization method. For comparison, holes were also made with traditional HSS twist drills. Based on the obtained test results, it can be concluded that the friction drilling method can be included in the energy-saving methods of making holes in thin-walled elements.
The presented paper contains a description of a new method of determining the optimum feed rate for a waste-free, energy-efficient drilling process being a friction drilling. Previous experience has shown that the energy required to drill a hole by friction drilling is closely correlated with the drilling cycle time. Based on the authors' own experience, the thesis was put forward that the optimum feed rate during the drilling procedure should be variable but smooth. Additional evaluation criteria for the developed method were the drilling cycle time, the maximum values of the axial force and torque, the maximum values of the feed drive and machine spindle drive load, as well as the energy consumption. The test rig was based on a numerically controlled machine tool, equipped with an axial force and torque sensor, and additional dedicated measuring devices for measuring energy consumption. The results of the study indicate the high competitiveness of the developed approach, compared to the feed rate control strategies in a friction drilling cycle known from the literature. The proposed approach for selecting the longitudinal feed rate can quickly gain a significant number of applications. Studies have shown that optimally planned feed rates can reduce energy intensity by up to 47%.
The results of the research, which aimed to analyze the acoustic properties of selected sacred buildings located in the city of Częstochowa, Poland are presented in the paper. Three architecturally unusual and completely different from each other churches were selected for the study. The churches differed in shape of their buildings, cubic volume, years of construction, interior furnishings, etc. Nine different objective parameters were used to describe the physical properties of acoustical field in the studied churches. Various factors characterizing the acoustic properties of each building were determined, such as the distribution of sound pressure level (SPL), reverberation time T30, definition D50. Next, they were thoroughly analyzed, so as to ultimately obtain distributions of individual acoustic parameters in the space of the tested building. It allowed to evaluate the quality of the received verbal or musical message depending on the place where the listener was. Further research on speech intelligibility and the musical quality of churches was performed by determining the averaged values of next four objective acoustic parameters: centre time Ts, speech clarity C50, music clarity C80, and speech transmission index (STI). A new approach to analyzing the objective physical parameters describing the sound field was presented in Sec. 4. Mean free path length and critical distance were determined for the investigated acoustic fields in each church and they were associated with a general geometric factor characterizing the complexity of the room shape. The final part of the work presents a comparative analysis of the obtained results of acoustic quality tests of the temples, and thus their usefulness in terms achieving a maximum intelligibility of speech and music. The interesting similarities were found in the spatial distribution of individual acoustic parameters characterizing the distribution of the acoustic field in temples with completely different architecture.
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