Acoustic-vibration Dynamical Modelling And Simulation Of Defective Ball Bearing

As the transmission support component of the system,angular contact ball bearings are widely used in various rotating machinery systems due to their special characteristics.However,because the bearing is mostly working under radial-axial combined load,high speed and heavy load circumstances,it is extremely prone to failure.At present,bearing failure has become one of the main causes of rotating machinery breaking down.The sliding motion between the ball and the raceway is inevitable when the ball enters and exits the load zone,it will cause the suddenly rise of working temperature and the deterioration of lubrication characteristics of the contact,resulting in the failure of the bearing element in severe cases.Therefore,it is urgent to study the influence factors of the skidding motion between the ball and the raceway,and propose measures to suppress the sliding motion;Impact impulses will be generated during the process of the ball passing through local defect,and the defect center line may not be parallel with the race line in practice.However,the relationship between the offset distance and bias angle of the local defect and the impact impulse response has not been clarified.Therefore,it is urgent to carry out the study of offset and bias local defect’s displacement excitation model,the study of relationship between offset distance as well as bias angle and bearing vibration charcteristics.The results provide a reference for accurate diagnosis of early local defects of angular contact ball bearings;The impact vibration caused by the surface defects will induce abnormal noise and it will affect the working performance of the mechanical equipment.However,the current noise model simply considers the motion and load state of the internal components and cannot obtain accurate noise characteristics of the bearing.The coupling model method of acoustic-vibaration of angular contact ball bearings is studied to provide a new reference for the noise monitoring and diagnosis of early local defects of angular contact ball bearings.The main work includes:(1)The skidding motion and lubrication characteristic between ball and raceways are not clear.To overcome this problem,the friction-vibration dynamic model of angular contact ball bearing is proposed,the influences of surface roughness,axial load on the motion of ball and lubrication characteristics at the contact are studied.The results can provide theoretical support for the method of suppressing the skid between ball and raceways.(2)The relationship between surface waviness and the abnormal vibration induced by it is not clear.To overcome this problem,an improved dyamic model is proposed to consider the roundness/waviness errors on the raceways of an angular contact ball bearing,the influences of ball’s revolution angular velocity fluctuation,waviness amplitude,axial load and roundness order on the spectra,statics of inner raceway acceleration and the motion of ball are studied.(3)The relationships between the offset,bias local defect and the impact impulse response caused by them are not clear.To overcome this problem,the dynamic model of an angular contact ball bearing with offset and bias local defects on raceways is proposed,the influences of offset distance and bias angle of local defect on time-frequency spectrum characteristics,statics characteristic are studied.(4)The acoustic of the angular contact ball bearing cannot be accurately described by the current model.To overcome this problem,the acoustic-vibration coupling model of an angular contact ball bearing is proosed,the influences of axial load,inner raceway speed on the acoustic of bearing is studied;the acoustic-vibration coupling model of an angular contact ball bearing with local defect is proposed,the influences of defect size on the acoustic of bearing is studied.