Tapered roller bearing early failure verification and test analysis

Tapered roller bearing is one of common types of rolling bearing, the failure pattern is a common fault in the course of using, tapered roller bearing failure types are complex, and bearing failure is very much also, in the form of reason is very complex, in order to better understand one failure forms, the bearing network ( Hereinafter referred to as:) Below to share is early invalidation form of taper roller bearings and related testing analysis. 1, the introduction of tapered roller bearings are shown in figure 1, tapered roller bearings can bear commonly the heavier radial and axial load joint word, also can be subject to pure axial load, mainly depends on the size of the bearing contact Angle, the bigger the contact Angle, the higher the axial bearing capacity. Figure 1 taper roller bearing, tapered roller bearing 2 early failure modes described the taper roller bearing is assembled in a certain type of car axle active on either side of the cylindrical gear, gear on each side to install a set of the bearing. Through the communication with the vehicle technician, learned that this type of bearing often occur in the process of using bearing burnt and maintains a fracture, the phenomenon such as bearing inner ring with roller damage, damage of concrete form is: fault bearing was badly damaged and bearing inner ring raceway is crumbling, light big curl rim and has worn loss, small guard eversion ( As shown in figure 2, 3) , the inner side with indentation depth of shaft spline ( As shown in figure 4) 。 Figure 2 inner circle was badly damaged and has big curl rim in figure 3 small guard eversion figure 4 inside there is depth throughout the indentation 3, tapered roller bearing wear failure form analysis is to point to in use process, two sliding or rolling and sliding contact surface micro convex body interaction, cause material constantly moving, mainly divided into two aspects of abrasive wear and adhesive wear. Abrasive wear is the result of insufficient lubrication or outside particle invasion, the degree of surface darkening owing to the different grinding grain and nature. Due to the rotating surface and keep the rack material is worn off, these grinding grain number increase gradually. Eventually wear into a process accelerated, resulting in bearing failure. Adhesive wear is material from the surface or to quenching tempering, the process will be in the contact region and local stress concentration may lead to cracking and spalling. 4, bearing failure test of fault bearing ring and roller has carried on the microstructure and hardness testing, testing structure as shown in figure 5 and table 1. Figure 5 inner ring quenching tempering organization, failure analysis fault bearing parts microstructure and hardness of the test results show that the inner ring in the process of using high temperature tempering, the tempering temperature shall be above 350 ℃. Bearing raceway surface shape wear, light should be lubricant inappropriate or lubricant supply cause; Inner ring guard and raceway adhesive wear occurred for the reason of failure on the roller axial load is too large and adhesive wear and tear caused by inadequate lubrication, the roller bit sticky occur face. Because of the bearing damage frequently, through the communication with customer technical personnel, the operating parameters of the bearing, and through Romax software simulation modeling, analyzing the bearing of life. The gear shaft for helical gear ( See figure 6) Gear on each side to install a set of 30215 bearing, bearing axial load rating for 41. 5 kn。 Axial force of the helical gear transmission is very big, through modeling analysis to 54. 5 kn。 Under normal circumstances, allow the axial load is not more than 50% of fixed load, bearing 30215 carry the load at this time is far more than the limit, they can afford on both sides of the calculation of bearing life of the gear for table 2 and table 3. Through the above analysis can be concluded that the bearing when use, because of the axial load is too large, squeezing roller bearing inner ring guard, the sliding friction, bearing temperature rise rapidly led ring to temper softening, make the parts surface to surface spalling and agglutination, dysfunctional roller in this case, inner ring after softening in roller greatly under the action of axial force, big guard crushed outer, eventually lead to bearing failure. 6, a solution based on the working condition of bearing used for understanding and found that originally in the design of the axle gear shaft helical gear, the bearing axial force is small, did not see bearing failures occur, but the helical gears in the transmission process, will produce large noise, customer response is strong in use. To reduce the overall noise, the helical gear changes to existing helical gear, the overall noise decreased obviously, but cause bearing significantly larger in the axial force, beyond bearing limit, make premature bearing failure. Using dedicated software Romax modeling analysis, the bearing failure reason should be caused by excessive axial load, therefore, on the bearing contact Angle adjustment, according to GB/T 297 standard for rolling bearing tapered roller bearing external dimensions, inner diameter is 75 mm maximum bearing contact Angle for 28 ° 48 '39 ', when the adjustment to the contact Angle, the calculation of bearing life tables 4 and 5, still can not meet the requirement of the user's vehicle life, recommend that users consider expanding bearing the dimensions or decrease the axial load bearing suffered from other aspects, in order to meet the requirements for the use of the bearing, avoid such failure from happening again. Warm prompt: in order to avoid premature failure of the bearing, according to the working condition, choosing the appropriate bearing is the most important. The choice of the bearing is an important work, careful, complex technology, which includes the choice of bearing structure, performance and service life calculation. When bearing selection, should the bearing to conduct a comprehensive inspection, found bearing whether meet the requirements as soon as possible, to prevent premature failure of the bearing, to ensure normal work.