Research On Equalization Of Roller Pressure Of Jacketed Roller Slewing Bearing

With the rapid development of marine economy, increasing attention has been attached to the development of large sized marine hoisting equipment as a supporting project of most marine engineering projects. Jacketed roller slewing bearing has become the most common type of slewing bearing because of its advantages of compact structure, low center of gravity, huge load capacity, etc. However, this type of slewing bearing has a marked disadvantage that is the uneven distribution of roller pressure among the rollers under working condition. It results in some rollers bearing too much pressure while some others almost bearing no force, which could significantly influence the safety of the overall machine and the life time of the slewing bearing.Relying on a research project jointly carried out with a domestic heavy industry enterprise, taking the jacketed roller slewing bearing of a large sized floating crane as the research object and using the finite element software ANSYS and APDL as the main research tool, this paper aims to solve the problem of uneven distribution of roller pressure of the jacketed roller slewing bearing by two respective ways, which are adjusting the stiffness distribution of the slewing bearing structure and adjusting the roughness of the slewing rails.Firstly, the impact of stiffness distribution of the slewing bearing structure on the evenness of roller pressure is studied. The finite element model of the slewing bearing which including the wheel-rail contact system is established based on the finite element software ANSYS. The stiffness distribution of the slewing bearing structure is adjusted by changing the layout direction, location, form and thickness of the stiffened plates in the box structure of the slewing bearing. Values of roller pressure obtained from finite element calculation are analyzed and compared, and the best structural form of slewing bearing is selected. The research indicates that the most beneficial layout form of the stiffened plates for even distribution of roller pressure is to equably layout the solid stiffened plates along the peripheral direction right above the slewing rails.Then, the impact of the roughness of the slewing rails on the evenness of roller pressure is studied under a fixed structural form of the slewing bearing. In the finite element software, the adjustment of the roughness of the slewing rails is simulated by adjusting the forced displacements in the wheel-rail contact area. To realize the iteration executed by the computer automatically to figure out the values of displacements of the rails which need to be adjusted to achieve the even distribution of roller pressure, several APDL programs are coded. The results show that even distribution of roller pressure can be achieved in the finite element software by the method proposed in this paper. To verify the feasibility of the method based on finite element software, which achieves the even distribution of roller pressure by adjusting the roughness of the slewing rails, an evincive experiment is designed and test of the physical model is conducted on site. The results show that adjusting the roughness of the slewing rails according to the proposed finite element method can improve the distribution of roller pressure significantly, that proves the proposed method is feasible.Finally, characteristics of the two methods are analyzed and compared. The way of combining the two methods to achieve a best equalization effect is described with an example.Results of this paper provide new design ideas and an economic and effective method based on finite element software for engineers who work on designing jacketed roller slewing bearings, which has actual application value in engineering field.