Analysis Of Lubrication Performances For Rolling Bearing Based On Real Rough Surface

The design of the capacity of the rolling bearings is based on the theory of Hertz, while Hertz theory only applies to the dry contact between a pair of smooth surface. But the rolling bearing roller and the raceway surface can not be absolutely smooth; at the same time, due to the presence of surface roughness, it cause the time-varying effects during the rolling bearing operation. Therefore, it is absolutely necessary to explore the rolling bearing contact surface roughness effects based on the mixed EHL theory.Firstly, the application of surface roughness profile measuring instrument measured the surface roughness data of disc specimens having a transverse texture; then, use the Fourier transform nonlinear to fit the function of roughness, superimpose the roughness function to the film thickness equation, thereby establish a Rolling mixing hot EHL model.Based on this model, fixing the rolling bearing parameters and the lubricating oil parameters without changing, by changing roughness data of the contact surface, apply the multigrid method, conduct a total of 315 set numerical calculation for heavy working conditions, quantitative analysis the effect of surface roughness on the lubricating properties of the rolling bearing. Summarizes the results of this study, the following conclusions can be drawn:(1) Compared with Hertz distribution, the pressure distribution and the stress distribution on rough surface contact have a big difference, and the greater the roughness, the more obvious differences between them.(2) As the “pump effect” of the surface transverse rough stripes, the average film thickness hav, r on rough surface contact is always greater than the film thickness value hav, s on smooth surface contact; and the larger the roughness σ, hav, r and hav, s the greater the difference.(3) In order to ensure the life of rolling bearings, we can select the oil viscosity reasonably or use appropriate measures to improve the precision of rolling bearings, trying to ensure the oil film thickness ratio is λ> 1.5, the λ being the ratio hav, r and σ, ie λ = hav, r / σ.(4) The lubrication of rolling bearings is closely related to the integrated roughness σ. As σ is increasing, its lubrication condition by a full film lubrication(λ>3), gradually transition to mixed lubrication state(1≤λ≤3); if the surface roughness σ continues to increase, it then becomes boundary lubrication(λ<1); accordingly, the contact load borne mainly by the lubricant film gradually transformed shared by the lubricant film and surface roughness peaks, until it is mainly responsible by the asperities.(5) The relationship between the maximum of main shear stress on the subsurface contact area τmax,r and the integrated roughness is parabola. For this article studied Rolling running condition, when σ<0.1(μm), τmax,r is less than maximum of main shear stress on the smooth subsurface contact area; when 0.1≤σ≤0.4(μm), τmax, r is only greater than τmax,s about 5%; but when σ≥0.6(μm), both differ by more than 15%.Additionally, this article through a large number of numerical results of the regression analysis for heavy working conditions, established theoretical formulas between contact stress of rolling bearing, the average film thickness and the integrated roughness. Establishment of these formulas, it has a positive meaning for perfecting rolling contact fatigue strength design.