Research On The Method Of Tooth Arrangement And Mechanical Properties Of PDC Radial Bearings

PDC(Polycrystalline Diamond Compact)radial bearing is a new type of bearing with high hardness,high strength,high wear resistance,high thermal conductivity,etc.It can be used in extremely harsh working environments without fear of corrosion and wear.Its performance is superior to conventional radial bearing.PDM is an important downhole tool in oil and gas production,and is widely used due to its own characteristics.As a key component of PDM,radial bearing has an important impact on the service life of PDM.The radial bearing of most screw drills has an open structure and it is directly lubricated and cooled using drilling fluid.This easily causes excessive wear failure of the radial bearing,which causes PDM to fail.Increasing the service life of radial bearing has an important impact on improving the service life of PDM.This paper proposes to use the PDC radial bearing as the radial bearing of PDM to improve the service life of PDM.According to the PDC failure mechanism,the load on the tooth surface has a great influence on the service life of PDC.This paper mainly studies the mechanical properties of PDC radial bearings under loadFirst of all,this paper analyzes the force of the upper and lower radial bearings of PDM.It can be seen from the calculation that the upper and lower radial bearings are different in force,so the upper and lower PDC radial bearings have different PDC teeth.Based on the size of Φ172mm PDM,the structural of teeth of single row PDC radial bearing(only one row of PDC teeth PDC radial bearings)and double row of PDC radial bearings(two rows of PDC teeth PDC radial bearings)are designed.The structural dimensions and the number of teeth of the single-row and double-row PDC radial bearing are obtained.In this paper,the motion of PDC radial bearing is analyzed,and the variation law of the overlapping area of single-row and double-row PDC radial bearings is obtained.In this paper,the motion of PDC radial bearing is analyzed,and the variation law of the overlapping area of single-row PDC radial bearing and double-row PDC radial bearing are obtained.Secondly,the three-dimensional numerical calculation model of single-row PDC radial bearing and the three-dimensional numerical calculation model of double-row PDC radial bearing are established.The mechanical properties of single-row and double-row PDC radial bearing are analyzed by finite element software.For the single row of PDC radial bearing,this paper studies the arrangement of PDC teeth,the number of teeth,the diameter of teeth,chamfering,radial load and the effect of clearance on its meclianical properties.Through finite element analysis,it is found that different arrangements have a great influence on the mechanical properties of PDC radial bearing;the number of PDC teeth has a certain influence on the mechanical properties of PDC radial bearing;the PDC tooth diameter has a certain stress peak for PDC radial bearing.The influence of PDC tooth chamfer on the stress fluctuation and stress peak of PDC radial bearing is large.Radial load of PDC radial bearing has a greater influence on the stress.The gap has a great influence on the stress of the PDC radial bearing,but has little effect on the stress change trend.For the double-row PDC radial bearing,the influence of PDC tooth arrangement,the number of teeth,the diameter of teeth,radial load,clearance and spacing on its mechanical properties are studied.Through analysis,it is found that the arrangement of PDC teeth,the number of teeth,the diameter of teeth,the radial load and the clearance have a similar effect on the mechanical properties of the double-row PDC radial bearing than the single-row PDC radial bearing.The spacing has little effect on the mechanical properties of the double-row PDC radial bearing.Finally,the paper compares the overlap area and stress of single-row and double-row PDC radial bearings,and combines the mechanical properties of single-row and double-row PDC radial bearings to propose a single-row PDC radial bearing.Finally,the paper compares the overlap area and stress of single-row and double-row PDC radial bearings,and combines the mechanical properties of single-row and double-row PDC radial bearings to propose a method of arranging teeth of single-row PDC radial bearing and a method of arranging teeth of double-row PDC radial bearing.This paper compares and analyzes the upper and lower PDC radial bearings of PDM,provides suggestions for arranging teeth of the PDC radial bearing teeth of the Φ172mm PDM,and introduces the trial production of the PDC radial bearing.