| Angular contact ball bearings(ACBBs)determine the security and reliability of mechanical rotor systems.Statistically,30% of the rotary equipment failure result from the bearing problem.To enhance the security and reliability of ACBBs,design reasonable structure of ACBBs and reduce the economic loss and casualties caused by mechanical system failure,it is important to solve a series of basic scientific problems,such as internal load distribution,bearing stiffness variation and vibration mechanism.However,dynamic characteristics of ACBBs have not been fully explained due to the variable load conditions,large speed variations,manufacturing errors,flexible deformation of bearing rings in special applications and coupling of axle-bearing housing.A study for the internal load distribution,bearing stiffness and vibration characteristics of the high speed flexible ACBBs with manufacturing error is very helpful.One of the main manufacturing error of ACBBs is the waviness error on raceway surface and ball surface.Moreover,the deformation of flexible bearing ring has great impact on bearing dynamic characteristics.How to describe the flexible ring deformation considering the coupling of axle-bearing housing and the manufacture error that both affect internal load distribution,stiffness and vibration characteristics of ACBBs are not fully resolved in current studies.To solve this problem,a high speed flexible ACBB with manufacturing error is studied in this paper.A dynamic model of high speed flexible ACBBs is proposed.The flexible ring deformation,coupling of axle-bearing housing and the manufacture error are considered in the developed model.The influences of the bearing load,rotate speed and different waviness error on the bearing dynamic characteristics are studied,some valuable conclusions are obtained.Thesis work carried out in the following areas:(1)Based on Hertz elasticity contact theory,difference of diverse contact stiffness calculation method is studied and the solution accuracy is investigated.4 different type of internal load distribution and stiffness calculation method of ACBBs are studied.the influence of the bearing load on the internal distribution and stiffness is studied by using4 different type of internal load distribution and stiffness calculation method of ACBBs.Considering the calculation accuracy and practicality of the 4 different type of internal load distribution and stiffness calculation method of ACBBs,a quasi-dynamic model of high speed flexible ACBB is proposed.the initial clearance,dimensional deviation,centrifugal expansion and flexible deformation of the ring are considered in the developed model.Considering the centrifugal force,friction moment and bearing housing contact force on bearing internal load distribution,the influence of flexible deformation of rings,bearing load and rotate speed on the internal load distribution and stiffness is investigated.(2)A quasi-dynamic model of high speed flexible ACBBs with manufacturing error is proposed.The waviness error on the ball and raceway surface is considered in the developed model.The influence of the waviness error on internal load distribution and stiffness is investigated.(3)A dynamic model of high speed flexible ACBBs with manufacturing error is proposed.The flexible deformation of rings and waviness error on the ball and raceway surface is considered in the developed model.The influence of the flexible deformation of rings on the vibration characteristics is investigated.Moreover,the influence of the waviness error on the raceway surface on the vibration characteristics is investigated.(4)Based on the internal load distribution solution,2 fatigue life calculation models of ACBBs are proposed.The influence of the internal load distribution of high speed flexible ACBBs on the fatigue life is investigated.Compared to the ISO 281:2007,the fatigue life of ACBBs is analyzed and predicted.(5)To obtain the optimization design of bearing structure parameters and rotor system,the influences of bearing raceway groove curvature radius coefficient,ring thickness and bearing initial contact angle on the vibration characteristics of ACBBs are investigated.Moreover,a dynamic analysis software of ACBBs is developed based on the previous proposed dynamic model.The software can easily analyze the dynamic characteristics of different bearings,and calculate the stiffness,contact load distribution and contact angle of ACBBs,so as to analyze the vibration characteristics of the normal ACBBs and ACBBs with manufacturing errors.In this paper,the internal load distribution and stiffness calculation method,dynamic characteristic calculation method and fatigue life prediction method of ACBBs are systematically described.The influences of bearing load,rotate speed,flexible deformation of rings and surface waviness error on the dynamic characteristics and vibration characteristics are investigated in the proposed model of high speed flexible ACBBs with manufacturing error.An optimization design method of bearing structure parameters and a dynamic analysis software of ACBBs is developed,which is very helpful for the selection and application of bearings and the dynamic analysis of bearings in the bearing industry. |
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