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The modification of the raceway profile in the double row slewing bearing

100%

Kania L. , Śpiewak S. , Pytlarz R.

Journal of KONES

2016

tom Vol. 23, No. 1

139--146

The slewing bearings are applied in heavy working machines and operated in extreme conditions. A characteristic feature of these bearings are a high load which determining a large deflection of a contact zone rolling element - raceway. This phenomenon combined with the effects of a bearing clearance causes a significant increase in a contact angle of the bearing. This in turn causes displacement of the contact zone to an undesirable position. In the construction of slewing bearing is applied of a large value of the osculation ratio. This leads to occur of large sizes of the contact zone identified in a radial cross-section. The sizes are comparable to values of the radius of the ball. The contact zone is type of quasi-linear. Effects of changes the position of the contact zone in the double-row ball slewing bearing has been presented in the paper. The raceway profile for such bearing consists of the arc section changing in the radial section. When the contact zone includes a change point of curvature of the raceway profile it comes to a concentration of a contact stress, and this is unfavourable for operation of the bearing. In order to eliminate this phenomenon to the profile introduced a transition curve. For this purpose was selected a clothoid. The curve ensures a gradual change of curvature from the arc section of the profile to the zero curvature of the straight profile section. The raceway profile becomes the smooth curve of the second rank. In the article are presented a numerical model of the contact zone for the double-row ball slewing bearing and the distributions of a pressure in the contact zone for the ordinary and modified raceway profiles. The calculation results have been presented as graphs of the distributions of the pressure along the contact zone. It has been shown that the introduction modification of the raceway profile eliminates the concentration of the pressure along the contact zone profile. The results obtained can be used during design of the raceway profiles of the double-row ball slewing bearing.

Numeryczna analiza współczynnika twardości w modelowaniu strefy styku łożysk tocznych wieńcowych

100%

Kania L. , Pytlarz R. , Reszka P.

tom Nr 1

62--65

W niniejszym opracowaniu przedstawiono próbę modyfikacji sposobu obliczania współczynnika twardości wałeczkowych łożysk wieńcowych z wykorzystaniem metody elementów skończonych. Współczynnik ten uwzględnia różnicę twardości bieżni i elementów tocznych. W przypadku zwykłych łożysk tocznych różnice twardości bieżni oraz elementów tocznych są niewielkie i nie wpływają znacząco na nośność tych łożysk. W łożyskach wieńcowych natomiast, ze względu na gabaryty bieżni, trudno osiągnąć takie twardości bieżni, jak elementów tocznych. Dlatego dokładne oszacowanie współczynnika twardości ma znaczący wpływ na poprawne określenie nośności łożyska.

In this article an attempt of modify the way of calculation the hardness factor in large roller bearings using finite element method has been showed. This factor takes into consideration difference between hardness of bearing’s tracks and roller elements. In common rolling bearings the hardness differences between tracks and rollers are small and they doesn’t affect meaningful at bearing capacity. In large roller bearings it’s hard to obtain the same hardness for tracks and roller elements because of tracks оѵегаІІ dimensions. For that reason accurate determine of hardness factor has considerable influence for correct determination of bearing capacity.