Surface Roughness Of Rollers Research Articles

Experimental study on polishing process of cylindrical roller bearings

The surface quality and accuracy of the geometry of the cylindrical rollers are important factors for bearing life. This paper presents effects of machining parameters on the surface roughness, topography and roundness of cylindrical rollers through the lapping and polishing experiments. And then the surface roughness of the cylindrical rollers is optimized. The results found that the surface roughness of rollers is significantly changed in lapping process with different abrasive particle sizes, while the surface roughness has slightly reduced in polishing process. It also indicated that the smoother surfaces with better roughness can be obtained after lapping and polishing process. In addition, the surface roughness of cylindrical rollers is rapidly reduced from Ra of 0.5 µm to Ra of 0.063 µm after the 3-h lapping process and Ra of 0.013 µm after the 1-h polishing process. The surface topography of rollers can be achieved by the smoother surface when loads are from 25 to 35 N in lapping process, and the loads are from 35 to 40 N in polishing process. Finally, the Taguchi method is applied to optimize the surface roughness in polishing process. The result found that the optimal surface roughness achieves 0.015 µm with respect to the time of 35 min and type of 4000# Al2O3.

Effects of surface roughness and type of oil on traction characteristics between steel rollers

Recent progress in the chemical engineering sector has made it possible to produce synthetic oils with high and low traction coefficients. This investigation is conducted to examine the effect of modifying the surface roughness of the cylindrical roller traction elements on traction when lubricated with synthetic and mineral oils. The surface roughness of the rollers is changed by a factor of 100 (peak to valley roughness R max = 0.03 to 3.0 μm). Eight kinds of synthetic and mineral oils are tested using a twin-roller machine designed and made by the authors. The traction coefficients are measured by changing the amount of sliding and also the direction of sliding. The duration of full elasto-hydrodynamic lubricating (EHL) conditions and the changes in the surface roughness of the test rollers are measured. The effects of surface roughness upon the traction coefficients of the synthetic traction oils are very small and the traction coefficients are hardly increased even when the surface roughness of the rollers is increased by a factor of 100. The effects are appreciable when mineral oils and a synthetic low-friction oil (olefin oligomers) are used. It is suggested that the contact surfaces of traction elements should be finished very smooth, like a mirror, to reduce wear and to prevent surface failure, because the traction coefficients under full EHL conditions are almost the same as those under boundary lubricating conditions in which the asperity interaction occurs.

Surface durability and surface failure of a thermally refined steel roller using a variable specific sliding type contact roller testing machine.

Thermally refined steel rollers are fatigue tested under three sliding-rolling contact conditions while varying the specific sliding during the rotation of a test roller by using a newly produced variable specific sliding type contact roller testing machine. With this method, the surface durability under each condition is elucidated. The test results obtained here are compared with the results obtained by a conventional rolling contact fatigue test with constant specific sliding. The relationships between the characteristics, such as frictional torque under each variable specific-sliding condition, and the surface roughness and pitting distribution on the test roller are discussed. The surface durabilities under variable specific-sliding conditions are lower than those under a constant specific-sliding condition. The roller surface roughness tends to be lower at a position of higher absolute value of specific sliding, and the amount of pitting tends to be greater at a position of higher absolute value of frictional torque.