Life Prediction Of The Rolling Bearing On The High Speed Shaft In Ship Unloader Trolley

The gear reducer of the trolley is the mechanism of the ship unloader to convey the power, and the quality has a direct impact on the integral performance of the ship unloader. The tapered roller bearings are important foundation of the gear reducer of the trolley, which support the shafts and the parts of the shafts, in particular, the work situation of the tapered roller bearings which support the high-speed shafts should be more attention, because some performance indicators such as their accuracy, performance, lives, vibration and reliability, play decisive effect to the trolley. The lives of bearings are one of the main factors which decides the mechanism life of the running reducer of the trolley, therefore increasing the fatigue lives of rolling bearings, ensuring the normal operation of bearings running, predicting before failure in the work have an important economic value.The traditional ways to predict the lives of the rolling bearings, become extremely complex, because they involve contact problems. The method of treatment is not only complex, long time, but also the unidirectivity contact which results inequality constraints is also the root causes of difficulting to deal with in math. Since the contact theory has been put forward by the pioneering Hertz, people have been trying to give analytical solution to the contact problem issues of elastomer, however, analytical solution of these can only be limited to a small number of simple and important geometric bodies. The contact formula of rolling bearings is a contact theory formula which after a series of simplified assumptions of the Hertz, therefore the analytical solution compared with the actual force have a certain degree of error. The gap between the bearing lives in actual applications and the theory bearing lives calculated according to Hertz theory will be further increase, and the load rolling bearings suffered in work is the random load which includes impact load, dynamic load and so on. Theoretical calculation is not enough rigorous only by a factor of impact load, dynamic load factor for life span. The fatigue experiment of rolling bearings also can get bearings lives, however, it is time-consuming, and slow to obtain experimental data, consuming a great deal of manpower and finance. And through the life experimental of bearings of the same group one by one, the values of bearing lives are also very discrete, even under the same working condition, the maximum life is often 50 to 100 times than the lowest life, and even if aware of the lives of one set bearings values, it can not be applied to other bearings, therefore it need to experiment about a large number of bearings which takes up a lot of resources.The modern bearing industry calculating engineering problems by finite element analysis made great achievements. Practice showed that, while the rolling bearings turning, it will bear friction moment, inertia force and other dynamic forces or static forces. Besides, between the rolling element and the rollaway nest of the rolling bearings exist lubricating oil which is used for preventing metal surface contact and reducing friction and reducing wear. These significantly improve contact fatigue lives of the rolling bears. Only on the basis of the rolling bearing stress analysis is accurate, can we predict the values of bearing lives more accurately.In this paper, the force of the high-speed shaft of the running reducer of the trolley was calculated, and the results in case of fully loaded of the rolling bearings were obtained. Analyzed the force of all the internal bodies of rolling bearings. Used Hertz theory to calculate the largest contact stress and deformation and the contact stress distribution under the surface of the largest ball contained of the tapered roller bearings SKF by 32211J2Q. Used the finite element software of ANSYS to calculate the contact stress value of the largest ball contained, and it was compard with Hertz theory.The condition of the bearings enduring preloaded force was considered in this paper, and preloaded force was calculated. Inertia force is produced in the interior of bearings in high speed rotation, therefore influence of inertia force on bearings was described. The condition of running bearings endured by friction force was considered in this paper. Lubricating theory of viscoelastic hydrodynamics was used to calculate the friction of outer rings and inner rings of rolling bearings. On this basis, firstly, finite element model of tapered roller bearing was established, three situations were considered for stress analysis, model under pre-load, model under pre-load and external load, model under pre-load,external load and inertia force. The results were compared. Secondly, Stress distribution in the half bearings was analysed separately in light load and full load condition.Rolling bearing fatigue life formula was used to calculat the rated life of a single ring ,and then rated lives of the whole set of bearing were calculated. Corrected formula of bearing rated life is used to correct rated lives.Functional relationship of damage probability (P), contact fatigue stress(S) and natural life (N) was established in ball bearing steels manual, and the S-N curve of GCr15 was established. According to the characteristic of rolling bearings stress constant amplitude loading time history and variable amplitude load time history added in parameter were compiled. And ariable extent stress time history was calculated with load spectrum. In this paper, in according to Miner linear accumulative damage theory, the fatigue analysis software of Fatigue was used to calculate the fatigue lives of bearings in constant load spectrum and variable load condition. And the two results were compared and analysised. As a result of stress amplitude on bearing had a great impact on the lives of bearings, the fatigue lives of rolling element with the largest load bearings at different variance load time history was discussed in this paper.In the final, the result of rolling bearings stress was analysed, and the variance of load time history was 0.05, in the fully or light loaded working condition. The fatigue lives aftermath of maximum contact stress poin in different rolling element was received. Factors which impacted fatigue lives of roller bearings were analysed.