| The early damage of the roller bearing of roller bit journal bearing(RBJB)limits the service life and working performance of the drill bit,and it is one of the urgent problems to be solved in the field of petroleum drilling.In recent years,some theories and experiments have shown that the bionic surface texture of proper parameters can improve the tribological performance of the roller bit sliding bearing,but the design and optimization of texture parameters is the key to whether the texture can be applied under working conditions.Therefore,in this paper,based on the numerical simulation analysis and the unit tribological experiment,a more systematic and meticulous study on the tribological properties of groove textured RBJB is developed.The main research results are as follows:(1)Based on certain assumptions,combined with the geometry equation of groove texture,the theoretical model for the lubrication of grooved textured RBJB is established,as well as analysis the influence of different working conditions and texture parameters on bearing capacity and friction coefficient of RBJB.The lubrication state of the drill bearing is different under different working conditions.Mastered the influence of various factors such as texture distribution angle,depth,area ratio,skew angle,width and length on the lubrication performance of RBJB.It provides a theoretical basis for the design of texture parameters of specimens in textured RBJB experiments.(2)Combined with the geometrical dimensions of the ring-block friction pair of the UMT tribometer and the actual working conditions of the RBJB,the experimental test piece and unit friction and wear experimental scheme are designed.Based on Hertz contact theory,the equivalent working condition is carried out,and the experimental environmental parameters are determined.Through the process research of laser scanning processing groove texture,the influence of laser processing parameters on the texture morphology is obtained.On this basis,the processing of groove-type textured ring specimens is completed.(3)The ring-block unit friction experiments under load conditions of 200N,300N,400N and speed conditions of 60rpm,120rpm,180rpm,and 240rpm are completed.The variation of the friction coefficient of the ring-block friction pair with the groove-type texture depth,area ratio,deflection angle and width under different load and speed conditions is obtained.The experimental research results are in good agreement with the theoretical simulation results.(4)The friction coefficient,wear amount and surface morphology of the wear scar are compared between the non-textured experimental group,the textured experimental group and the silver-plated experimental group.The experimental results show that the friction coefficient of the texturing experimental group can be reduced by 39.1%and the wear rate by 58.3%compared with the non-textured experimental group.The friction coefficient of the silver plating experimental group can be reduced by 35.3%and the wear rate by 68.7%compared with the non-textured experimental group.To sum up,in this paper,the design method of groove-type textured roller head sliding bearing is established by numerical simulation and ring-block friction sub-unit simulation experiment.By comparing the tribological properties of the ring-block experimental group with different surface treatment methods,the results show that the groove-textured ring-block experimental group has the best comprehensive lubrication and wear reduction performance.The research results provide a basis for the design and optimization of the groove textured RBJB,it is of great significance to promote the biomimetic surface texture technology in the field of RBJB research and application. |
PDF Full Text Request