Wheelset Cold Pressing Process Parameters

1) crimp contact Pressing speed will affect the friction coefficient of the sliding friction process of the wheel seat surface along the wheel hub hole surface, the properties of the contact surface and the temperature, etc., crimp contact pin thus causing chemical changes, deformation, wear and heat in the surface layer, which will eventually affect the press-fit quality of the wheelset.
2) Busbar straightness, roundness and cylindricity. TB/T 1718-2003 stipulates that busbar straightness ≤ 0.015 mm, roundness shape tolerance is 0.02 mm, and the cylindrical shape tolerance of the vehicle wheel seat and wheel hub hole after processing is 0.05 mm.
3) contact socket crimp Friction coefficient. crimp contact female The ratio of the friction force on the contact surface to the positive pressure is the friction coefficient. The press-fitting force is determined by the friction coefficient when the interference is constant, and the magnitude of the press-fitting force is inversely proportional to the fatigue strength of the contact surface. Therefore, when the interference is constant, the fatigue strength of the mating surface can be improved by reducing the friction coefficient and reducing the press-fitting force.
4) crimp contact male Surface roughness. TB/T 1463-2006 stipulates that the surface roughness Ra of the integral rolled steel wheel hub hole is not greater than 3.2 μm, and the surface roughness Ra of the locomotive axle wheel seat is not greater than 1.6 μm.
5) crimp socket contact The size of the press-fitting force is related to factors such as the axle, friction coefficient, processing quality of the hub hole, press-fitting tooling, press-fitting speed and interference
amount. The press-fitting force should be reduced as much as possible during the axle press-fitting process to increase the preload.
6) female crimp contact Interference is generated during the interference fit of the wheelset because the diameter of the wheel seat is larger than the diameter of the hub hole. Its size
is the difference between the two
7) male crimp contact Press-fitting curve and end point pressure. The only criterion for checking whether the press-fitting is qualified is the pressure
size of the press-fitting curve and the end point of the press-fitting curve.
4 Acceptance index of wheel set press assembly
The acceptance index of a wheel set after press assembly is that the diameter difference of the two wheels of the same wheel set shall not exceed 0.5 mm, and the wheel position difference shall not exceed 1 mm; the inner measurement distance of the wheelset is 1 353±2 mm, and the difference of the three-point distance measured on the inner side of the wheel hub after press assembly is not greater than 1 mm; the radial runout of the rolling circle of the two wheels relative to the center line of the shaft shall not exceed 0.3 mm; the phase difference of the residual static imbalance position is 180°; the end face runout of the inner side of the rim of the two wheels relative to the center line of the shaft shall not exceed 0.8 mm. The wheelset should be subjected to a dynamic balance test after assembly.
5 Conclusion
The process of cold press assembly of wheelsets is simple, convenient, and does not require heating or oiling processes, but there are also some drawbacks in the press assembly process. If the press assembly quality of the wheelset does not meet the specified requirements during the press assembly process, the wheels may loosen and the inner spacing of the wheels may exceed the tolerance during the train driving, which will cause the train to derail and threaten the driving safety. Therefore, in the process of wheel press-fitting, in order to prevent the relative movement between the wheel and the axle, the tightening force between the wheel and the axle is regarded as a relatively important process parameter. In the actual press-fitting process, the fit between the wheel and the axle is strengthened mainly by adjusting the tightening force during press-fitting. This method is easy to destroy the stress distribution at the press-fitting fitting surface, resulting in stress concentration, which will cause the hidden danger of early failure of the axle and wheel seat or crack germs, and reduce the safety and service life of the axle and wheel seat [5]. Therefore, in order to overcome the above-mentioned drawbacks, it is necessary to analyze and study the wheelset press-fitting process. The problems such as strain that occur during press-fitting are studied to improve the product qualification rate; through the analysis and research of the article, the tightening force of the wheelset is improved to enable it to bear a larger load, improve safety, reliability, and extend service life.