| During recent years as the strategy for high speed and heavy load was brought forth, the wheelset which is a critical component of wagon, work in a worse environment and therefore the phenomenon of fatigue occur frequently, posing tremendous threats to security and economy. To fundamentally improve the fatigue performance and extend the lifetime of wheelsets, the paper, revolving around the two points which are residual stress due to machining and the press-fit quality respectively, using a combination of theoretical analysis, computer stimulation and experimental study, studies the key technology for guaranteeing the cold processing quality. The main conclusion is presented as follows.Firstly, the distributing area, the macro shape and the growth period of a crack is analyzed, and the main causes of crack growth are revealed. The two factors which most influence the axle performance in the stage of cold processing are summarized.Secondly, through experiment statistics, the influencing rule of machining on the distributing of residual stress is analyzed, and the rule of residual stress on axle fatigue performance is analyzed by stimulation as well. Based on works presented above, the paper proposes an approach to improve the residual stress distribution condition by ultrasonic peening. The testing result indicates that the surface stress of the axle has been transformed to compressive stress which is helpful to fatigue performance.Lastly, the press-fitting process is analyzed by stimulation and the influencing rule of press-fitting process parameters on indicators which are firstly proposed in this paper to evaluate the press-fitting quality of wheelsets. Those process parameters are optimized by orthogonal test to guarantee the press-fitting quality powerfully.Through improving the cold processing quality of wheelsets, the results of the paper are of importance to both security and economical efficiency of the railway freight cars. |
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