The Research On Railway Axles' Processing Methods And Equipments

Railway axle is one of the most important parts in locomotive and vehicle. The security of the train just depended on the axles'quality. It needs lots of manpower, material resources and financial resources if any change to the railway axles because the mass and the involved aspects of the railway axles. Thereby , we are all cautious to any change to the railway axles. Now , more than half of century later, we have made great accomplishment on high speed, over loading and light railway axles techniques. There are substantial evidences which can prove that safe and high efficient axle techniques will make the railway transportation secure and efficiency. At the same time , the development of the railway transportation will provide the railway axle technique huge motivity besides the wild market for the relate industries which maybe one of the most important new economic increasing points.The research on the longevity of the axles attach importance to the security of the axles ,and then ,impact the railway transportation secure. Through working over the load and stress on the axles , we can know that the axles support the train body , redirector and endure the counterforce of the cartwheel which is transported from the rail. At one time ,the axle endure the drive and trig force that comes from the gear device. Because all of these load , there are turning bend stress and torsion stress when the train move. As a whole , there are three kinds of load on the axle which are load above reed,drive load and trig load . On the Cyc effect of the above three load , it proves that about 2/3 damnification to the axles are arosed by fatigue . And the main pattern of the invalidation is Cold cut . To avoid Cold cut , we suggest that we should pay more attention to the following five aspects : 1 structure design optimize ; 2 material ;3 surface strengthen treat ;4 technics of the assemblage of the wheel and axle ;5 examine and repair. Research and practice can prove that the longevity and security of the axles will heighten if choosing the right material , designing appropriate D/d ,improving the radiusρand making unloading groove. And then if we can regularly examine the axles , we may put an end to the Cole cut of the axles.Our country is a railway-big country and the number of axles we need every year is bigger than 300,000. Thereby ,it is very important to look for an processing method to produce axles with high efficiency and good quality as well as improve the security and longevity of the axles.At the present time,the railway axles are manufactured by free forging or radial forging. Both of the two manners have disadvantages ,for example low producing efficiency, inferior producing circumstance and low utilization of materials and so on .Cross wedge rolling is a kind of processing method which can process the parts with a few cutting or no cutting. Because it's strongpoint of sequential and partial forming manner, Cross wedge rolling show it's particular advantage in ladder axles parts producing. At present time ,there have been hundreds of rough parts which are manufactured by Cross wedge rolling , for example the axles used in cars , tractors ,motorcycles, and gas engines .But , because the big size of railway axles, the cross wedge technique can not be used to produce railway axles at the present time . During the large-scale axle is rolling by cross wedge rolling machine , as the diameter of the axle becomes bigger , the most tensile stress goes up ,but the most Shear stress becomes lessening . Then , the damnification caused by the bigger diameter to the center of the parts is slight . So, big diameter axle parts can be rolled by cross wedge rolling methods .There are two main cross wedge rolling machines at the present time which are roller cross wedge rolling machine and shutter cross wedge rolling machine. Both of the two kinds of machines have limitation when they are used to rolling large-scale axles. Big diameter sector die will be needed if the large-scale axles are rolling by roller cross wedge rolling machine and is very difficult to produced . At the other side , shutter cross wedge rolling machine can not manufacture large-scale axles too because it's short of stiffness. So , although large-scale axles can be manufactured by cross wedge rolling technique in the theory, they can not be used in practice because of the shortage of equipments .Unidirectional Continuous Flat Wedge CWR Machine which combined the advantages of the two kinds of CWR machine and spurned theirs disadvantages can ensure the machine stiffness as well as simplify the die producing. In addition, it used unidirectional continuous feeding technique and design of chain moulding board which can solve the problems of too long moulding board and too huge size of the machine. Then , unidirectional continuous flat cwr machine solved the difficult problem of the use of cross wedge rolling technique in rolling large-scale axles ,and it is a excellent equipment to manufacture large-scale axles beside railway axles. It's advantage can be described as following :○1 Better machine stiffness , high forming precision ;○2 larger range of the parts which can be rolled ;○3 high producing efficiency , high energy utilization etc.To make sure that the unidirectional continuous flat wedge CWR machine can be used in practice earlier , I have designed the die and processing flew for rolling the railway axles。The processing flew was made as following : cut axle billet and blanking→heat up the billet→roll the axle→cooling→cut both ends . After all of the above processing flew , we should turning and grading the axle to reach the demand of the precision . Finally , the axle need be heat treated , and then ,it had better be influence quenched which can obviously heighten the intension of the surface , improve the longevity of the axle and enhance the axle's security. The security of the train just depended on the axles'quality.And , the number of the axles we need every year is big .Then , how to produce axles with high grade and hige efficience heavily impact the development of the railway . In this paper , After the reaserch on the longevity of the axle was done , the other keystone is how to produce the axles through the cross wedge rolling , and then I hope all of the above reaserch can do something for the railway transport of our country .