| Self-lubrication spherical plain bearing is a kind of spherical sliding plain bearing with the advantages of simple structure, impact resistance, large load capacity, selflubricating and self-aligning. With the increased requirements in the aerospace,railway machinery and other fields, the higher safety and reliability of the bearing are required. The failure of the bearing can lead to serious consequences which can’t be predicted. The self-lubricating fabric woven liner is the key factor which can influence the load capacity and service life of the self-lubricating spherical bearing. The wear failure is the main failure mode of the self-lubricating bearing, and the wear process is mainly the process of the formation and the desquamation of the PTFE transfer films.The wear mechanisms of the transfer films on the friction surfaces became hot issues in the tribology fields. Therefore, the investigations on the failure mechanism of the self-lubrication spherical plain bearing and the establishment of the physical model for the failure mechanism to obtain reasonable failure criteria have important significance to improve the bearing tribology performances. With the wear tests of the spherical plain bearing, the main factors which can affect the wear lives of the self-lubricating spherical plain bearing were analyzed and the failure mechanisms of self-lubrication spherical plain bearing were discussed.By means of orthogonal experimental design, the optimum levels and the main factors have been found out and the tribological properties of the liners by different graft modification treatments were studied. The results show that the bonding performances of the liners could be improved through grafted modification compared with those of the unmodified bearing. The friction and wear properties as well as the oscillating frequencies of the self-lubricating spherical plain bearing were obviously correlational. With the increase of the oscillation frequencies, the friction coefficients and the wear rates decreased, while the friction temperatures rised. The friction coefficient, the wear loss and the friction temperature of the modified bearing were much improved compared wih those of the unmodified bearing. It shows that the liners after modification could improve the tribological properties of self-lubricating spherical plain bearing.The accelerated life tests of the self-lubricating plain bearing were carried out,and the failure criteria for the wear loss and the friction temperature of the sphericalplain bearing were established. The impact of the working conditions and the graft modification on the failure of the spherical plain bearing were analyzed. Compared with the calculated theory service lives, the performance of the test bearing was evaluated. The wear characteristics of the bearing liner worn surfaces were deeply analysed by observing the changes of the morphologies during the process of the friction and wear of the spherical plian bearing with scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS), and the failure mechanisms of the spherical plain bearing were discussed. The physical failure model of the selflubricating plain bearing was further established.The paper has important referencial values for the amendment of the failure criteria and prolonging the service lives of the self-lubricating plain bearing. |
