Railway freight car rolling bearings taper roller crown research development profile

In the research of railway freight car rolling bearings taper roller convexity development profile, 2018 - 09 - 30 a overview, rolling bearing roller roller is the roller in rolling bearing, in theory it is line contact contact with the race, so roller can bear larger load. Bearing is working, the rotation of the roller is the main movement itself, and the revolution of the race. The actual use and test results show that roller is the most vulnerable parts of the rolling bearing, roller design level of the rolling bearing working performance ( Such as rotating accuracy, vibration, noise and flexibility, etc. ) Has a great influence. In current railway freight car rolling bearings, application is more crown roller bearings, because the crown roller better solve the stress distribution of roller bearing in operation, slow roller edge fatigue failure, make the service life of the bearing under the condition of equal 1 - higher than that of straight generatrix roller 2 times. Therefore, the correct design of the surface of the roller shape is one of the important work to ensure the quality of bearing. Second, the mechanism of roller with crown shape roller fatigue spalling is from both ends of edge, this is due to the edge of the working roller has caused by stress concentration phenomenon. Roller contact stress on the edge is mainly caused by two reasons. Roller in the work of a is due to the load in two edges, the contact stress is large, the deformation is large, and the change is very different, this is the so-called edge effect. As shown in the figure below. In this case, the maximum stress of the edge of & sigma; Max1 and & sigma; Max2 several times larger than central roller stress, edge effect range of L1 and L2, calculations show that L1 and L2 roller busbar total length is about 0. 07 - 0. 16 times. Another is due to the influence of many factors, cause ring deflection, the stress of general deflection to 1 - larger than the calculated 2 times, but the main reason for the roller edge stress concentration, and the effect of edge effect. Can do a visual interpretation of edge effect, as shown in the figure below. After being squeezing roller under the raceway material compressive deformation, outside the raceway of roller materials without compression deformation, make the roller race at the ends of the material in the tensile state, increased the ability of resistance to compression deformation, compression deformation is small. Therefore, when approaching from between roller and ring, deformation will be larger on both ends of the roller, it can be understood as the edge stress concentration. The stress concentration will seriously affect the bearing capacity and fatigue life of rolling bearings. The effective ways to reduce or even eliminate the stress concentration is change the generatrix shape roller, the roller diameter can reduce on the sides, using roller with crown. Above for the crown of the tapered roller contact stress distribution, it can be seen that the roller edge stress is improved, the crown in the roller load bearing can improve the bearing life - 1 2 times. Three, foreign railway vehicle special-purpose rolling bearing roller crown research development situation in the late 1950 s, the United States and the European developed countries through a lot of experiments and theoretical analysis, prove that the bearing roller surface with a crown, can better solve the roller in the working stress distribution, delay the roller edge fatigue failure, make the service life of the bearing under the same working conditions, higher than that of straight generatrix roller 1 - 2 times. In the mid - 1970 - s, the Swedish SKF, Germany, Britain, France, Japan and other countries have the mature technology of a complete set of, the production of cylindrical roller, tapered roller, needle is fully realizing the crown. Four, China's railway freight car rolling bearing roller crown research general situation of the development of China's railway departments, research on domestic railway truck special-purpose rolling bearing surface of the tapered roller hyperbolic crown technology research, 1999, approved by the ministry of railways issued documents, transportation design institute quartet vehicles' 352226 x2 - Type 2 rz railway freight car rolling bearings product design patterns', the type of bearing roller as per 20 grains, less than 1 grain of type 197726 rolling bearings, roller bus using logarithmic curve, inner ring raceway crown design, inner ring big guard adopt bevel guard, the rubber sealing structure using labyrinth seal, In 2001, wafangdian bearing group co. , LTD. , luoyang bearing ( Group) Company, northwest bearing ( Group) Co. , LTD. , Shanghai united bearing co. , LTD. , chengdu bearing group co. , LTD. 5 trial production; Stop production of the original type 197726 rolling bearing in 2002. （ Source: the resources of railway vehicle platform)