Wpływ rozkładu wad lokalnych na charakterystykę drgań łożysk kulkowych

Local defects in ball bearings may occur at the center line of raceway and its surrounding areas. However, most current studies were concentrated in studying the influence of the local defect located at the centerline of raceway on the bearing vibrations, where the effects of local defects surround the centerline were ignored. To overcome this problem, based on Hertzian point contact theory and multi-body dynamic algorithm, a multi-body dynamic model considering the offset and angular distributions for a ball bearing with a local defect on its outer raceway is established. The influences of offset distance and skew angle between the geometric center of local defect and the centerline of outer raceway on the bearing vibrations are investigated. The relationship between the offset distance and the impulse waveform characteristics is obtained, as well as that between the skew angle and the impulse waveform characteristics. The results show that the offset distance and skew angle of the local defect have a great influence on the time-domain impulse waveform characteristics of the bearing accelerations. This paper can provide a useful guidance for the accurate diagnosis of early local fault in the ball bearings.Wady lokalne łożysk kulkowych mogą występować na linii środkowej bieżni oraz w otaczających ją obszarach. Jednak większość dotychczasowych badań nad wpływem wad lokalnych na drgania łożyska koncentruje się na wadach linii środkowej bieżni ignorując oddziaływanie wad zlokalizowanych w obszarach otaczających tę linię. Aby rozwiązać ten problem, w przedstawionej pracy wykorzystano teorię kontaktu Hertza oraz algorytm do analizy dynamiki układów wieloczłonowych, co pozwoliło na utworzenie modelu dynamiki układu wieloczłonowego uwzględniającego przesunięcie i rozkłady kątowe łożyska kulkowego z lokalną wadą na bieżni zewnętrznej. Badano wpływ wartości przesunięcia i kąta nachylenia między geometrycznym środkiem wady lokalnej a linią środkową bieżni zewnętrznej na drgania łożyska. Otrzymano zależności pomiędzy wartością przesunięcia a charakterystyką przebiegu impulsu, a także między kątem nachylenia a charakterystyką przebiegu impulsu. Wyniki pokazują, że wartość przesunięcia i kąt nachylenia wady lokalnej mają duży wpływ na przebieg przyspieszeń łożyska w dziedzinie czasu. Praca dostarcza pożytecznych wskazówek na temat trafnego diagnozowania lokalnych uszkodzeń łożysk kulkowych w ich wczesnych stadiach

Optimization of Glycerol Extraction of Chlorogenic Acid from Honeysuckle by Response Surface Methodology

Using honeysuckle as raw material, chlorogenic acid (CGA) was extracted with different alcohols. Based on the single-factor experiment design, the relationship between each parameter and the response value was explored by Box–Behnken method to optimize the process conditions. Best extraction results were obtained under the conditions of solid-to-liquid ratio of 1:20, the ultrasonic time of 40 min, the ultrasonic vibrator power of 240 w, and the CGA extraction rate of 2.98%. The experimental data show that the extraction rate of CGA is related to the length of the alcohol carbon chain and the number of hydroxyl groups in the extractant. The results from this work can provide technical basis for the safe and efficient production of CGA from honeysuckle

Research on work roll contour for improving the flatness defect of electronic aluminum foil

Electronic aluminum foil strip has extremely large width-thickness ratio, and often emerges tight-edge and rib-wave defect after rolling. In order to improve the special flatness defect, the defect distribution characteristics, section profile of aluminum foil strip and defect cause are analyzed, and then a new work roll contour is designed based on the idea of partial variable diameter. The new contour curve is a combination of multiple curves and the influence of various curve parameters on the contour is researched. A finite element simulation model based on ABAQUS is established to study the control characteristics of flatness defect when using the new work roll. The simulation results and actual production data of the 1450 aluminum foil rolling mill show that the new work roll can increase the depression of tight-edge area and improve the flatness defect of tight-edge and rib-wave.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Effects of solid-solute magnesium and stannate ion on the electrochemical characteristics of a high-performance aluminum anode/electrolyte system

Aluminum is an attractive anode material for electrochemical energy storage and conversion devices, but the passive film and parasitic corrosion of aluminum anode in aqueous solution limits its development. Herein, we investigated the electrochemical performance of Al-2Mg alloy in alkaline electrolyte containing stannate ion via hydrogen evolution tests, electrochemical measurements and surface analysis. It is found that the solid-solute magnesium in aluminum matrix activates the oxide film and decreases the cathodic sites, which negatively shift the aluminum anode potential. Furthermore, the doping magnesium ion in the oxide film facilitates the tin deposition reaction on the surface of aluminum anode, and the uniformly deposited tin inhibits the parasitic corrosion reaction. As a result, Al-2Mg alloy in 6 M NaOH solution with 0.05 M Na2SnO3 exhibits low hydrogen evolution rate of 0.015 mL.cm(-2).min(-1) with the inhibition efficiency of 95% at open circuit and negative electrode potential of -1.81 V vs. saturated calomel electrode at 20 mA cm(-2)