Analysis On Mechanical Characteristics Of Tapered Roller Bearings For Large Boring And Milling Machine Spindle

Tapered roller bearing is a key component for large boring and milling machinespindle. The mechanical performance of tapered roller bearing could directly affectmaximum speed, rotational accuracy, rigidity, processing performance, noise andtemperature-rising of the machine spindle, which then affects accuracy and quality ofthe processing parts. Research on the mechanical properties of large tapered rollerbearings has been carried out using theoretical calculation method due to limitation ofexperimental conditions. Large tapered roller bearing can be analyzed as a flexiblebody by using the finite element method, and the actual working conditions of thebearing could be better simulated under the finite element condition. Thus, themechanical characteristics of large tapered roller bearings can be obtained.Taking the tapered roller bearings for large boring and milling machine spindle asresearch object in this dissertation, the finite element model of tapered roller bearingwas set up. Distribution features of contact stress between roller and raceway as wellas distribution rule of maximum stress along roller profile were analyzed. Effects ofaxial clearance on the distribution range of contact stress and maximum roller contactstress were studied. Furthermore, effects of some factors, such as radial load, axialload, moment of work and the number of rollers, on contact stress distribution of rollerand raceway were analyzed.Based on simulation technology of the whole flexible body, the explicit dynamicmodel of tapered roller bearing was established by using finite element method.Movement rule of the inner ring, rollers and cage of bearing was analyzed, and thevariation of contact stress of bearing parts with time was obtained. Also, variationtrend in contact stress of cage lintel place in and outside loads region was analyzed.Changing characteristics of contact stress along roller profile in the rotation processwere investigated.According to the structure and working conditions of tapered roller bearings, fatigue life of tapered roller bearing was calculated. Effects of axial clearance, radialload and moment on fatigue life of bearing were discussed. Results showed thatfatigue life of bearing could greatly varied due to change in the vicinity of zero-clearance of axial clearance, while fatigue life of bearing significantly increased due todecrease of work moment.Mechanical properties of large tapered roller bearings, including contact stressdistribution, dynamic characteristics of flexible body and fatigue life, were analyzed inthis dissertation. The research results could provide a reference for optimization designof tapered roller bearings.