Wyniki wyszukiwania - Biblioteka Nauki

1

Wpływ wybranych czynników na przebieg docierania żeliwnych skojarzeń ślizgowych

100%

Nosal S. , Grześkowiak J.

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tom nr 2

505-513

PL

W referacie omówiono badania dotyczące wpływu chropowatości technologicznej, prędkości ślizgania i sposobu wykonania odlewu na przebieg docierania żeliwnego skojarzenia ślizgowego.

EN

This paper concerns running - in of cast iron sliding pair. It presents the influence of technological roughness on reliable running - in, temperature, frictional resistance and critical load. The tests were performed on friction machines. The paraffin oil lubrication was applied. Samples (disks) were made of cast iron ZlCu1,4PVB taken from the marine engine cylinder liner and the counter - sample (plates) from the cast iron piston ring applied in the same engine. Roughness of the samples was: R(a1) = (0,19 - 0,26 i m), R(a2) = (0,50- 0,66 žm ), R(a3) = (0,80 - 1,05 |žm). The ratio of the number of tests finished with the running - in to the whole number of tests was assumed as a reliability index of running - in 0. The change of this index, in relation to technological roughness of samples, is presented in the FIG. 1. Temperature and frictional resistances were, during the whole period of running - in, higher for sliding pairs with samples of roughness R(a2) than with the ones of R(a1) - FIG. 2. These parameters were also on a higher level. The previously described tests were carried out at the sliding speed V = 0,56 m/s, whereas the next ones at V = 4; 6; 8 m/s. On the basis of the counter - sample temperature measurement results they determined the critical value of load (FIG. 4) which did not cause, yet, the occurrence of the scuffed white layer on the surface of the counter - sample and the sliding pair scuffing. On the basis of carried out tests they found out that the reliability of cast iron sliding pair running - in is the best when technological roughness is close to roughness occurring after the running - in. In order to avoid scuffing of important cast iron sliding pairs their temperature should be monitored and protected from exeeding to exceed the critical value.

2

Laboratoryjna ocena wpływu nacisku i prędkości ślizgania na intensywność zużycia stali obręczowej gatunku B6T przy suchym tarciu ślizgowym

100%

Witaszek M. , Witaszek K.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2008

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tom z. 64

267-274

PL

Koła kolejowe są odpowiedzialnymi elementami o dużym wpływie na bezpieczeństwo i niezawodność przewozów. Ich zużywanie, będące skutkiem tarcia pomiędzy kołami a szynami, jest ważną przyczyną utraty właściwości użytkowych. Zużywanie to zależy między innymi od takich czynników, jak nacisk i prędkość ślizgania. W pracy przedstawiono wyniki badań wpływu tych czynników na zużycie stali gatunku B6T stosowanej na obręcze kół lokomotyw.

EN

Rail wheels are responsible elements with significant influence on the transport safety and reliability. Their wear, caused by a wheel - rail friction, is an important cause of wheels deterioration. This wear is strongly influenced by such factors as contact pressure and sliding velocity In the present work the influence of tat factors on dry, sliding wear of a tyre steel grade B6T is studied. This steel is used for locomotive tyres manufacturing.

3

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

80%

Witaszek M. , Witaszek K.

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tom 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.

4

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

80%

Shanmughasundaram P.

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tom 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.