Optimization Of The Machining Technology For Crankshaft Thrust Faces

Crankshaft is one of the most important components in automobile engine; and thrust face of crankshaft is the register reference to the finish manufacturing. At the same time, thrust faces of crankshaft are also the reference to make sure the components in the right positions in engine. The traditional way to machine the thrust face of crankshaft is grinding. Finish turning and rolling process is a new way to machine the surface in nearly 20 years. Through this process, the surface quality of the part is better than grinding, much more efficient, and avoid surface burned. Meanwhile, Finish turning and rolling process can increase the hardness of the surface, reduce the roughness, and increase the abrasion resistance and corrosion Resistance. It is a very worth spreading way to the face finish machining.During the process of machining and using, there is still a problem. The fatigue lives of less than 10% ductile cast iron crankshaft thrust faces are not long enough. The mission of this thesis is to find out the possible reason why this phenomenon happens, and give the right way to improve the machining process.During the research, first, the influence of the finish turning and rolling process to the quality of thrust faces are studied here. Through the experiments, the microstructure changes after turning and rolling are analyzed, the influence on face roughness and hardness are summarized. Using the FEA way, the residual stresses in different directions of the part surface and the rules are found out. But in this part, no factors are found that do harm to the thrust face quality and the fatigue life.Then, the influence of the thrust surface quality to the using process is discussed. Finish turning process can bring bur into the face, and the influence of the bur has something to do with the relative movement direction. The analysis suggests that when the rotary direction of both machining and using are opposite, it is good to the surface fatigue life. But in fact, when the two rotary directions are opposite, it is easier to abrasion, so the influence of bur is excluded here. The shape of ferrite in the thrust face is changed during the finish turning and rolling process, when the rotary...