Superfinishing Of Bearing Rollers And 3D Simulation Of Surface Topography

Short cylindrical roller bearings widely used in railway locomotives demand extremely high quality. Through centerless superfinishing technique is often adopted in the process of machining the roller surface. The roller generant adopts straight one in traditional design and during the running the whole effective length is all under load. Although the contact stress distribution is even on most of the contact zone, serious edge effect is arisen at the two ends and results in the stress peaks several times higher than the mean stress, and earlier fatigue failure often occurs in the inner and outer of the rollaway and the roller itself. Application practice shows that rollers of straight generant can't meet the requirements of thigh speed and heavy load in railway transportation, and the roller design of appropriate generant is needed. At present in order to overcome this disadvantage factor, the roller generant shape has to be amended, such as adopting the bowtype roller, amendatory linetype and convexity ratio roller, whereas Chinese bearing factories adopt bowtype roller which is machined on two ends in one process .Not only is the low productivity, but also the surface roughness is very high, and what is more the ideal logarithm generant can't be produced in this process. The regular centerless grinding is unable to meet the above requirements simultaneously. There have been some literatures expounded all kinds of parameters of abrasive stone superfinishing and the influence of superfinishing effects, but short of detailed, direct theoretical and graphic description. From the above two aspects, firstly based on different rollers, different generant shape, the studies are systematically done from design principle ,material-choosing principle ,heat treatment criterion and machining process and so on., and the problems of the supporting rollerdesign and its manufacturing are solved and the optimal generantroller-----logarithm roller is made. The machining surfaces of highprecision is acquired, and the contact fatigue strength and operating life of the bearings are raised, and the irrational problems of the contact stress distribution are thoroughly solved. Secondly, a motion and a cutting model of abrasive stone superfinishing are built respectively, and optimal process parameters and conditions are acquired. At the same time it is clearly shown that the topography of the roller surface and abrasive stone cutting quantity are affected by the rotational speed of the roller, the vibration frequency and altitude of the abrasive stone and so on. The theory proof is provided for abrasive stone superfinishing technique through computer simulation, and cutting factors and conditions of better surface machining quality are obtained, and the application prospect of the abrasive stone superfinishing technique is expanded.