Study On Contact Stress Of Rock Bit Floating Ring Journal Bearing

The rock bit is the major tool of petroleum drilling, witch's service life directly depends on the life of bearing system. The rock bit journal bearing system has it's particularity on bearing structure, supporting load, the working environment and the relatively rotational speed between sliding sets, compared with the general mechanical journal bearing. The development of rock bit is tendency to realize high drilling-speed for the future. As a important component of rock bit, how to raise working reliability and the service life of the rock bit journal bearing are the problem that now solves urgently.In the design of a new 8 1/2" high speed rock bit, thread-locking ring and floating ring journal bearing separately replace ball-locking installation and journal bearing of the present general rock bit. With thread-locking ring, it can raise the axial location and locking ability of roller, to reduce the possibility of roller-breaking off in the course of getting into with high speed; with floating ring journal bearing, it can reduce the sliding velocity of adjacent two friction surface, thus this not only can raise the rotational speed of entire bearing system and not lose the capacity that support load, also can reduce the loss of friction power and the rise of temperature.Making the full use of the theoretical knowledge of FEA, contact mechanics and friction wear, and integrating with the research of other domestic and international scholar. This paper studies the condition that thread-locking ring gets power to distortion, and establishes the dispersed mathematics calculation model of contact stress, oil film pressure, wear and life prediction of the outside and inside of floating ring journal bearing. In addition, contraposing to the uneven distribution of contact stress of ordinary floating ring journal bearing, this paper introduces other three types of modification curve of outsideand inside of floating ring journal bearing—arc curve , correction curve (straight line +intersecting circular arc) and logarithm curve respectively. Through the emulating analysis and calculation of software that author programs according to the calculation model, it shows that modification design will do well favor to improve distribution of contact stress of floating ring journal bearing, and have notable meaning to raise bearing wear life.