Wyniki wyszukiwania - BazTech

1

Lubrication Behavior of the POE/R452A Mixtureat Different Sliding Velocities under Starved Lubrication Conditions

Górny Kasper, Tyczewski Przemysław

Tribologia

|

2024

|

nr 1

43--56

EN

There are no international standards guiding tribological testing in oil-refrigerant mixtures. The conditions for tribological tests, including sliding velocity, are chosen arbitrarily. The article presents an attempt to examine the influence of the sliding velocity of friction pair elements on the coefficient of friction and lubricating properties of compressor polyester oil (POE) and its mixture with the R452A refrigerant (POE/R452A) under starved lubrication conditions. The R452A refrigerant is currently widely used in transportation refrigeration. The authors’ original test procedure with the use of a model block-on-ring type friction pair was applied to evaluate the lubricating properties of the oil-refrigerant mixture. Tests were conducted in three operational situations: no lubrication, starved lubrication with POE oil, and starved lubrication with the POE/R452A mixture. In each case, the tests were performed at different sliding velocities and the same sliding distance. A series of tests was also conducted where the load was increased in steps by 20 N to determine the relationship between the coefficient of friction, sliding velocity, and load on the friction pair The results support the potential use of higher sliding velocities and the reduction in test duration. For starved lubrication with the POE oil and the POE/R452A mixture, the differences in wear at specific velocities for the same sliding distance reached up to 30%, and the rankings of lubricating properties at different velocities remained unchanged.

PL

Badania tribologiczne w mieszaninie olejczynnik chłodniczy nie są objęte żadnymi międzynarodowymi normami. Stosowane warunki testów tribologicznych, w tym prędkość ślizgania, są dobierane w sposób uznaniowy. W artykule przedstawiono próbę sprawdzenia wpływu prędkości ślizgania elementów węzła tarcia na wartość współczynnika tarcia i właściwości smarne sprężarkowego oleju poliestrowego (POE) i jego mieszaniny z czynnikiem chłodniczym R452A (POE/R452A) w warunkach skąpego smarowania. Czynnik chłodniczy R452A jest aktualnie szeroko wprowadzany do stosowania w chłodnictwie transportowym.Wykorzystano własną metodę oceny właściwości smarnych mieszaniny olej–czynnik chłodniczy z wykorzystaniem modelowego węzła tarcia typu rolka–klocek. Wykonano badania przy trzech sytuacjach eksploatacyjnych: bez smarowania, przy skąpym smarowaniu olejem POE i przy skąpym smarowaniu mieszaniną POE/R452A. W każdym przypadku wykonano testy przy różnych prędkościach ślizgania i takiej samej drodze tarcia. Wykonano również serię testów, w której skokowo zwiększano obciążenie ze skokiem 20 N celem określenia zależności współczynnika tarcia od prędkości ślizgania i obciążenia węzła tarcia.Wyniki badań potwierdzają możliwość wykorzystania większych prędkości ślizgania i skrócenia czasu przeprowadzania testów. Przy skąpym smarowaniu olejem POE i mieszaniną POE-R452A różnice dla poszczególnych stopni prędkości przy tej samej drodze tarcia wznosiły maksymalnie 30%, a rankingi właściwości smarnych dla różnych prędkości pozostają takie same.

2

Wear Analysis of Iron Slag Reinforced Polyester Composites with Taguchi Optimization

Vijaya Kumar Nimmagadda, Basha Shaik Ahammad, Kishore Chitikena Chaitanya, Aswarthanarayana Potli, Kumar Prathipati Pradeep, Maruthi Rao Marthati, Ravi Babu Sajja

Ecological Engineering & Environmental Technology

|

2023

|

Vol. 24, iss. 6

221--229

EN

In this paper, the dry sliding wear behaviour of the polyester composite reinforced with iron slag as filler was studied experimentally. The Taguchi method-based experiments were carried on pin-on-disk wear test set-up. The control factors considered for studying wear rate were sliding velocity, slag percentage and normal load applied on the member with constant sliding distance. The output performance parameters considered were coefficient of friction and weight loss. From the analysis of variance (ANOVA), it was observed that coefficient of friction is significantly affected by normal load then followed by slag content and sliding velocity. Sliding velocity plays a vital role on the weight loss, then followed by slag content and normal load. The optimal factor combination obtained was sliding velocity = 50 cm/s, slag percentage = 30 % and normal load = 4 kg. The model was validated using the set of optimal factor combinations to conduct a confirmation experiment.

3

Tooth Contact Analysis of Cylindrical Gears with an Unconventional Tooth Profile

Batsch Michał, Wydrzyński Dawid, Przeszłowski Łukasz

Advances in Science and Technology. Research Journal

|

2022

|

Vol. 16, no 4

119--129

EN

The paper presents mathematical models of cylindrical gear pairs with various types of tooth profiles, such as eccentric-cycloidal, concavo-convex Novikov type, and involute. Comparative analyses were provided for the aforementioned gear meshes, aimed at determining contact patterns, sliding velocity, and transmission errors. Tooth surface modifications were also considered. The results were compared with findings for a conventional involute gearing. It was found that the contact pattern in Novikov conformal gearing is 30% greater than in the involute gear pair, and 60% greater than in the eccentric-cycloidal gear pair. The smallest sliding velocity was obtained in Novikov gearing, which may be beneficial in terms of durability.

4

The influence of selected factors upon the value of external friction concerning plant granular materials

Wójcik A., Frączek J.

Tribologia

|

2017

|

nr 4

107--113

EN

The issues relating to the description of friction with regard to plant granular materials are fairly complicated due to a variety of factors determining the process. Considering each factor in isolation is insufficient and offers a limited insight into the phenomenon of friction. Therefore, the paper presents the research results concerning the influence of three independent factors (seed moisture content, sliding velocity, load) upon the value of friction force. The analysis showed the high statistical significance of the factors at play. The proposed mathematical model proved well fitted (considering granular materials) to the observed outcome of the measurements.

PL

Zagadnienia związane z opisem tarcia roślinnych materiałów ziarnistych są bardzo skomplikowane ze względu na wieloczynnikowe uwarunkowania tego procesu. Pojedyncze rozpatrywanie tych czynników jest niewystarczające i daje bardzo uproszczony obraz zjawiska tarcia. Dlatego w artykule przedstawiono wyniki badań dotyczące wpływu trzech niezależnych czynników (wilgotność ziaren, prędkość posuwu, siła nacisku) na wartość siły tarcia. Przeprowadzona analiza wykazała wysoką istotność statystyczną tych czynników. Zaproponowany model matematyczny uzyskał dobre (jak dla materiałów ziarnistych) dopasowanie do wyników pomiarów.

5

Effect of temperature, load and sliding velocity on the wear behavior of AA7075-SIC composites

Shanmughasundaram P.

Mechanics and Mechanical Engineering

|

2017

|

Vol. 21, nr 1

85--93

EN

Dry sliding wear behavior of a aluminum matrix reinforced with SiC composite was investigated under three different temperatures (30°C, 60°C, 90°C), three different load and sliding velocities against a EN 32 carbon steel counter face. Results showed that load and temperature have significant effect on the wear loss. Wear resistance of the composites decrease with temperature, load and sliding velocity within the observed range. Taguchi method was used to find the significance of the parameters. Analysis of variance (ANOVA) was used to investigate the influence of parameters on the wear resistance. It was found that the load was the most dominant factor influencing the wear followed by temperature and sliding velocity.

6

Friction-induced oscillations of a non-asbestos organic pin sliding on a steel disc

Nosko O., Nagamine T., Mori H., Sato Y.

Acta Mechanica et Automatica

|

2015

|

Vol. 9, no. 2

84--88

EN

Friction-induced oscillations result in deterioration of performance of disc brakes and are generally undesired. We conduct experimental study of friction-induced oscillations in a non-asbestos organic material / steel pair used in disc brakes of motor vehicles. The tests are done by use of a pin-on-disc machine in which the pin sample is supported on a deformable beam. The adjustable friction parameters are the disc velocity, contact pressure and temperature. The tests show that the friction coefficient decreases with the sliding velocity and increases with the temperature. The friction-induced tangential oscillation of the pin sample occurs with a frequency equal to the first natural frequency of the beam. The effects of the disc velocity and temperature on the oscillation characteristics are investigated. The oscillation amplitude increases with the disc velocity on the interval of velocities below 2 m/s. Temperature changes of several tens of degrees Celsius lead to the oscillation occurrence / decay. The obtained results can be useful for prognostication of friction-induced oscillations in disc brakes with non-asbestos organic pads.

7

Changing the load-kinematic parameters of bevel gears with biconvex-concave teeth during operation

Kuznetsova A.

International Journal of Applied Mechanics and Engineering

|

2012

|

Vol. 17, no. 3

885-892

EN

The change in the shape of biconvex-concave teeth profile as a result of bevel gears teeth wear was established experimentally. The wear influence on the tooth curvature radiuses, the rolling and sliding velocities of mating profiles and the teeth contact stresses was examined. The characteristics, which affected the wear process, were determined. A three-dimensional picture of the teeth wear distribution was presented.

8

Wpływ nacisku, prędkości ślizgania i twardości na zużycie przy suchym tarciu stali na obręcze kół kolejowych

Witaszek M., Witaszek K.

Tribologia

|

2009

|

nr 4

267-274

PL

W artykule przedstawiono wyniki badań zużycia wybranych trzech stali węglowych. Badania przeprowadzono na zmodyfikowanym stanowisku Timkena, przy suchym tarciu ślizgowym. Wyniki badań pozwoliły na określenie zależności intensywności zużywania badanych stali od wybranych parametrów charakteryzujących własności materiału (twardość stali) i warunki współpracy (nacisk i prędkość ślizgania). Zależności te opisano za pomocą równania wykładniczego. Wykorzystano je wraz z wynikami badań metalograficznych do analizy merytorycznej otrzymanych wyników badań zużycia.

EN

In this article, wear test results of three carbon steels (B6, C54 and C55) are presented. These tests have been performed on a modified Timken wear-testing machine in dry sliding conditions. To obtain an initial point contact (like in wheel – rail system), two cylinders with perpendicular axes have been used as elements of the tested pair. One of them had a motionless specimen, and the second one had a counter-specimen rotated around its axis. Volume loss and apparent contact area vs. load, sliding speed, and sliding distance were determined. On the basis of these results, the linear wear rate and contact pressure were calculated. Results of these calculations have been utilised to determine the influence of pressure, sliding speed, and material hardness on the wear rate of the tested steels. These influences have been mathematically described with an exponential function, which was used to analyse the wear behaviour of the researched materials. Optical microscopic observations of worn surfaces were carried out to study wear mechanisms.

9

Experimental investigations of shaft/gland packing friction pair wearing characteristics

Gaft Y. Z., Zagorulko A. V.

Problemy Eksploatacji

|

1998

|

nr 3

113-113

EN

Wear measurement results of iron, steel and bronze sleeves pair with different gland packing in dependence with contact pressure and sliding velocity are presented in paper. Effectiveness of some methods of friction surfaces hardening evaluation is done. According to measured data the law of wear distribution is defined and its statistic characteristics for different friction pairs are defined. It is stated, that shaft/packing contact wear subjects the normal law of distribution, and wearing is stationary ergodic process. The results, which were obtained, make basis for elaboration of reliability factors computational methods for stuffing - box seals of rotating shafts.

PL

W artykule przedstawiono wyniki współpracy tulei żeliwnych, stalowych i brązowych z różnymi uszczelnieniami dławnicowymi w zależności od nacisków stykowych i prędkości ślizgania. Dokonano oceny efektywności niektórych metod utwardzania powierzchni tarcia. Stosownie do danych pomiarowych zdefiniowano prawo rozkładu zużycia oraz jego charakterystyki statystyczne dla różnych par ciernych. Stwierdzono, że zużycie stykowe wał-uszczelnienie podlega prawu rozkładu normalnego, a zużycie jest stacjonarnym procesem ergodycznym. Uzyskane wyniki tworzą podstawę do opracowania obliczeniowej metody współczynników bezpieczeństwa dla uszczelnień dławnicowych wałów obrotowych.