Experiment Research On Vibration Characteristics Of Polycrystalline Diamond Thrust Bearing Group

Diamond thrust bearing group is one of the key components of the downhole motor,whichcontain with the rotationfriction vibration and other harsh conditions during drilling.It is likely to cause the diamond broken,shed,weared.The reliability and service life of diamond thrust bearing has become the focus of the development down-hole drill.In this paper,we use the 105 diamond thrust bearing group to study its axial vibration characteristics.Firstly,the working conditions of the diamond thrust bearing in the actual drilling process are analyzed.By simplifying the vibration model of the diamond thrust bearing group and its type of the periodic vibration,step vibration and sawtooth vibration,which provides a theoretical basis for the analysis and research of diamond thrust bearing group.In this paper,a set of diamond thrust bearing vibration simulation experiment system is designed,which includes rotary output,rotary drive shaft,drill pipe support fixture and distance gauge fixture.Then the system is assembled and commissioned.It has the functions of providing rotation,simulation of friction,transmission of vibration,swept vibration,test the vibration response of diamond thrust bearing group.The experimental results show that the first-order natural frequency,the second-order natural frequency and the three-order natural frequency of the diamond thrust bearing.The natural frequency of 50 Hz,90Hz and 189 Hz,this frequency range should be avoided in down-hole drill,by which can reduce the resonance damage.The vibration characteristics of the diamond thrust bearing group is studed under different vibration types.The experiment shows that:(1)Diamond thrust bearing group shake violently in the vicinity of 50 Hz 90Hz and 189 Hz,which should try to avoid in the thrust bearing design;(2)Study on vibration of thrust bearings should be discussed separately from the outer and inner.The vibration experiment system developed in this paper can provide simulation conditions for the subsequent vibration test of downhole tools.The research can provide the reference for the optimization design of the diamond thrust bearing group and the bottom hole assembly(BHA).