Abstract
In this paper, through analyzing Tc bearing by the theory of Hydrodynamic lubrication, the unsteady Reynolds equation of Tc bearing under the dynamic-state condition is initially established. The formula of Tc bearing’s liquid-film dimensionless stiffness coefficient and damping coefficient is derived. Furthermore, two kinds of the distribution curves of Tc bearing’s liquid-film dimensionless stiffness coefficient, damping coefficient against Tc bearing’s eccentricity ratio and width-diameter ratio are displayed respectively, and the stability criterion of liquid film is worked out and the angular speed of instability of bearing shaft is calculated. Overall, conclusions are drawn: downhole system improves the entire system’s stability by enhancing the stiffness of bearing shaft itself. The improvement of the stability of bearing shaft itself, which can be done by altering the structure of Tc bearing and adopting better spiral flutes and ellipse groove can strengthen the whole system’s stability. The high width-diameter ratio of Tc bearing increases the liquid film’s stiffness coefficient and damping coefficient of Tc bearing. The rotational rate of rotary table is lower than half of that of the supporting system of Tc bearing.
Highlights
With the advantages of small radial size, great bearing capacity, good impact resistance and good vibration resistance, etc., downhole tools with rotary dynamic seal mode, such as the continuous wave pulse generator, may have their rotary dynamic seal mode replaced by magnetic coupling to construct Tc bearing in order for longer service life
What’s special to Tc bearing is that there is no need to take lubrication flow and temperature rising into account, when soaking in the drilling fluid, of which the flow rate is up to 20-30 m/s, with particles whose granularity is 74 μm
Conclusions can be drawn from the former distribution curves of the non-dimensional stiffness coefficients: Firstly, with the increase of eccentric ratio and width-diameter ratio, four absolute values of liquid-film dimensionless stiffness coefficients are growing
Summary
With the advantages of small radial size, great bearing capacity, good impact resistance and good vibration resistance, etc., downhole tools with rotary dynamic seal mode, such as the continuous wave pulse generator, may have their rotary dynamic seal mode replaced by magnetic coupling to construct Tc bearing in order for longer service life. Tc bearing require being cooled and lubricated by drilling fluid. Speaking of its working principle, it is a special dynamic lubricated bearing. What’s special to Tc bearing is that there is no need to take lubrication flow and temperature rising into account, when soaking in the drilling fluid, of which the flow rate is up to 20-30 m/s, with particles whose granularity is 74 μm. In order to prevent the flush effects of drilling fluid as well as the tear and wear of particles, tungsten carbide alloy powder [1] and blocks of high hardness are sintered on the surface of bearing’s steel body to form tough contacting surface
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
