Research On Friction And Wear Characteristic And Structural Optimization Design Of PCD Sliding Thrust Bearing

With the development of drilling equipment,rotary steering drilling systems have become more and more widely used in the drilling of complex wells such as horizontal wells and directional wells.The stability of the work of the offset mechanism determines the accuracy and efficiency of steering,low speed and heavy load,and formation solidification.Factors such as strong abrasiveness of phase particles and insufficient lubrication seriously affect the service life of the sliding bearing assembly of the offset mechanism.In order to explore the performance of PCD sliding bearings in the bias mechanism,this research takes a certain type of PCD sliding thrust bearings as an example to study its friction and wear characteristics and structural optimization design.Combined with the working condition of the PCD sliding thrust bearing of the bias mechanism,the main wear form,wear mechanism and influencing factors of PCD as the friction pair material were analyzed.Based on this,the indoor PCD sliding thrust bearing friction and wear test frame was designed.The influence of factors such as lubrication,conditions,load,speed,solid phase particle characteristics on the tribological characteristics of PCD sliding thrust bearings are analyzed.It is proved that the wear resistance of PCD material is strong,the friction coefficient is stable at 0.04 under the drilling fluid environment,and the volume wear rate is less than 300mm~3/h,which meets the working stability requirements of the bearing of the rotary steering offset mechanism;however,there are alternating stress and stress Concentration causes the PCD block to break.In order to alleviate the edge cracking of PCD,the finite element numerical simulation software was used to analyze the influence of the structural parameters of the PCD sliding thrust bearing on the stress distribution and change of the PCD.The basic constraint conditions for the optimal design of the structural parameters were proposed.The optimal structural parameter combination of thrust bearings is a combination of 12mm diameter with(31,32).