| The turbodrill is turning toward the high speed,the high efficiency and the small diameter direction develops,which require the turbodrill thrust bearing can operate reliably in harsh working condition,such as high speed,heavy-load,high-temperature and drilling fluid lubrication condition.This paper carried out flow field analysis that reveals the different structure forms of thrust bearing distribution of solid phase volume fraction.By the coupled thermo-mechanical analysis,different bearing contact form surface temperature distribution has been solved,and the temperature rise influenced by drilling condition has been analyzed.By establishing drilling fluid mixed lubrication model,the point contact mixed lubrication characteristics for turbodrill have been analyzed,it is concluded that the Non-newtonian properties of drilling fluid,the bearing surface roughness and the ellipticity influence law for drilling fluid lubrication film thickness,film pressure and temperature rise.By establishing the finite element model of surface indentation and surface fatigue,the bearing surface indentation formation rule and influence factors of indentation,and bearing surface fatigue use factor have been obtained.The main research contents as follows:Aiming at three typical high-speed turbodrill thrust bearings,based on drilling fluid two-phase flow theory,the single ball fluid domain analysis model is established.By ananlyzing the drilling fluid properties influence on the the deposition of solid particles,it provides the foundation for bearing surface indentation formed by drilling fluid solid phase.Based on bottom-hole temperature field model and the thermo-mechanical coupling theory,the point contact thrust ball bearing and surface contact thrust bearing thermal coupling analysis gets the temperature rise influence by axial load and rotational speed.It demonstrates the bearing surface temperature rise of turbodrill is more sensitive to axial load.The turbodrill thrust bearing axial load should be strictly controlled in the process of drilling application,this provides the theoretical basis for different forms of bearings that applied in field.The power law type drilling fluid mixed lubrication for point contact has been established,through the method of numerical calculation,the Construct Rough Surface and the Gaussian Rough Surface impact on mixed lubrication characterristics has been analyzed,Bearing slip ratio,ellipticity and surface texture direction influence on drilling fluid film thickness,pressure and temperature rise also been discussed.Through drilling fluid mixed lubrication for point contact research,it reveals drilling fluid film bearing capacity,lubrication property and lubrication failure mechanism,which provides theoretical basis for turbodrill rotation speed control,avoiding bearing in dry friction,establishing an effective mixed lubrication and improving the efficiency of drilling fluid lubrication.The high speed turbodrill bearing surface indentation forms are obtained by the field tests.Based on the theory of elastic-plastic press in the bearing surface,the model of drilling fluid solid particles lead the bearing surface indentation has been established,the bearing surface indentation parametric analysis carried out by the finite element method.The plastic deformation of spherical solid particles,the bearing surface plastic strain and stress and the surface material extrusion bulge are obtain,which demonstrates the shape and material of drilling fluid solid impact on the surface indentation.The surface friction coefficient influence on bearing surface indentation shape also has been analyzed.The high speed turbodrill bearing surface fatigue crack forms are obtained by the field tests.Based on the theory of cumulative fatigue damage and Dang Van stress evaluation method,the bearing surface fatigue analysis model is established,the bearing surface fatigue use factor has been analyzed by finite element method.The surface hardening layer thickness,steel ball radius,surface indentation influence on bearing surface fatigue also been analyzed.This provides a new method for the turbodrill thrust bearing surface fatigue assessment. |
