Modeling and mechanical properties of rolling bearing damage mechanism analysis

Rolling widely used in aviation engine rotor, high speed CNC machine tool spindle, high-speed train wheels for high-speed rotating machinery system, the mechanical properties and the operating state has an important influence on the accuracy of the rotor system, reliability and service life. In the high-speed, high acceleration and other unconventional conditions, centrifugal, gyroscopic torque, friction, heat distortion, incentives and other factors external load significantly affect the dynamic behavior of the high-speed rolling bearings, bearing internal forms of exercise becomes very complex, rolling element and the bearing, between the outer ring in addition to the pure rolling contact, accompanied by spinning (spinning) and yaw (skidding) and other sports: bearing contact angle and the contact load distribution has undergone significant changes, so for the high-speed rolling bearing failure mechanism analysis and Troubleshooting becomes more difficult.
        For critical major equipment, early fault diagnosis of major significance, but reflect the speed of the response signal early bearing failure is not obvious, and susceptible to interference noise transfer path and work and other factors. This is not obvious relationship between intrinsic motivation and the dynamic response of the fault, so that fault diagnosis technology based on signal processing and feature extraction facing new challenges. Roller Bearing Fault diagnosis, scholars for a long, a lot of research and development based fault detection and diagnosis of vibration, acoustic emission and other signals, the Indian scholar Patl the status of Rolling Bearing Fault Diagnosis reviewed ls]. Compared fault detection technology Roller bearing fault modeling theory and failure mechanism is particularly inadequate. In recent years, rolling bearing fault modeling by scholars for more and more attention. GM's US cao spherical roller bearings for the establishment of a complex dynamic model to study the surface damage, preload and radial clearance and other issues.
        Nonlinear models bearing model and gear saw al hi Australian scholar of the time-varying integration, simulation and damage local spalling failure of the bearing. Professor Chen Guo, Nanjing University of Aeronautics and Astronautics established a rotor comprising a rolling bearing fault of a rolling bearing casing disaster combined model and studied the rolling bearing outer ring, the inner ring kinetics modeling and rolling injury Rafsanjani of Iran to establish a rolling bearing non-scholars linear dynamics model, given the inner ring, an outer ring and rolling mathematical description of local damage. Indian scholars Patel established deep groove ball bearings kinetic model to study the vibration response of the bearing inner and outer rings single point and multi-point failure.
        Professor Shi Linsuo 31 Second Artillery Engineering College established mathematical model of random vibration partial failure of rolling bearings, bearing failure simulated vibration response when [l41. Northwestern University Professor Wang Zhongsheng after the establishment of a 6-DOF fault bearing dynamics model, which takes into account factors varying stiffness and nonlinear rolling slide caused by the bearing clearance time, and the introduction of unit resonator simulation fails high-frequency vibration IBI bearing element.
        For the above-mentioned study of dynamic simulation of rolling bearing fault, contributed to a deeper understanding of bearing failure mechanism and characteristics, to a certain extent, it can provide a theoretical basis and foundation for the monitoring and fault diagnosis of rolling bearings. Most of the existing models do not consider rolling bearing fault more parameters affecting the speed, working temperature, external loads, etc., and therefore need to improve the accuracy of the model; most for rolling bearing fault modeling is aimed at dynamic response simulation after injury, while failure Research on the mechanism of insufficient rarely discuss in particular the initiation and development of bearing evolution of high-speed rolling bearing damage during operation. This paper considers the rotating inner centrifugal expansion and thermal expansion deformation of the rolling bearing model Jon es proposed improvements, build a high-speed rolling bearing mechanical model and experimental verification. We study the conditions inside the rolling bearing static load, dynamic load and high speed, etc. contact load, variation of contact position, and the damage mechanism and early bearing the injury site were analyzed to provide a theoretical speed for the identification and fault diagnosis of rolling bearing damage in accordance with.
        2 High Speed ​​Rolling theoretical modeling and model validation
        2.1 Improved model Jo nes Jon es Rolling Rolling model is more complete bearing mechanical model, but it does not consider the temperature rise due to the expansion of work and the centrifugal force caused by the deformation. In this paper, considering the effect of centrifugal force and gyroscopic moment on the basis of taking into account the effects of thermal expansion and the inner bearing radial centrifugal expansion of the bearing inner child what displacement of Jon es Rolling model is improved, making it more practical.
        l) What is the relationship analysis of seven typical rolling bearing children how to structure shown in Figure 1, with the thought of finite element will be seen as having a rolling bearing inner ring and an outer ring nodes node unit, the movement of each node contains 5 degrees of freedom two rotational degrees of freedom in order to facilitate analysis, considered fixed outer ring. Bearings in high-speed rotation and load bearing, the inner ring, the balls and the relative position of the outer ring geometry is changed. When the bearing load and balance, bearing inner ring and rolling elements are moved to the new location.
        2) by the force balance, high-speed rotation state angular contact ball bearings, the contact angle of existence, the ball bearing inner and outer rings of the question, the contact is not pure rolling contact, accompanied by spinning and sliding and other sports. To simplify the problem in practice, it is assumed ball at one of the inner or outer ring raceway as only pure rolling, and in another raceway and spinning motion exist. Consider rolling body suffered centrifugal force and gyroscopic moment, in the flat balls and ball bearing center axis composed of stress analysis.
        2.2 Model Validation
        1) Rolling stiffness verification mountain inside the rolling bearing contact angle, contact load can not be measured, it can not be directly verified. Bearing stiffness is a function of load and deformation of the contact, if calculated correctly, that the whole model is correct, so choose the bearing stiffness as the verification standard model. Selection of a high-speed rolling bearing spindle inside the system to validate the theoretical model, within the system of the spindle bearings are produced by German G MN angular contact ball bearings, two front bearing type One of HYKH61914, the rear end of three bearings HYKH61911, back to back configurations. The bearing stiffness values ​​calculated by the proposed model with standard rigidity G MN company l20] provide contrast, as shown in Table 2. Under light preload, the preload and heavy preload all three cases, the results were well matched with the standard value, the maximum error of 1.1%, to verify the accuracy of the theoretical model.
        2) Rolling dynamic characteristics of high-speed running state verification in order to study the state of rolling bearings in high-speed running state changes, the high-speed spindle is mounted on a CNC milling machine, system dynamics was observed with the variation of velocity. The experiment shown in Figure 4. In the machine coordinate system, Z axis as the main axis, X and Y-axis table feed direction, respectively. There simulation tool cutting teeth; bearing preload oil pressure to the hydraulic pump output 1O0Ps i (bearing preload the equivalent of about 17 2 8N).
        Use hammer K ist le r 9 7 2 2 (sensitivity: 2. 13 mv plus) stimulated N) J, and with a laser vibrometer po lyt eeho FV- 5 3 4 dynamic response measurement tip, and finally the force signal and vibration response signal input modality test software to get the experimental frequency response function. When the spindle speed is 12 0 0 0: / m in, the tip of the spindle system simulation and experimental comparison of the frequency response function in Figure 5 (a) and (b) below.
        Overall, although the experimental frequency response function is interspersed with a large number of spindle speed multiplier interference, simulation and experimental frequency response function can still be a good match. The simulation tool cutting teeth; bearing preload hydraulic pump output hydraulic set 1O0Ps i (the equivalent bearing preload approximately 17 2 8N). Use hammer K ist le r 9 7 2 2 (sensitivity: 2. 13 mv plus) stimulated N) J, and with a laser vibrometer po lyt eeho FV- 5 3 4 dynamic response measurement tip, and finally the force signal and vibration response signal input modality test software to get the experimental frequency response function. When the spindle speed is 12 0 0 0: / m in, the tip of the spindle system simulation and experimental frequency response function shown in contrast. Overall, although the experimental frequency response function is interspersed with a large number of spindle speed multiplier interference, simulation and experimental frequency response function can still be a good match.
        4-speed rolling bearing damage mechanism analysis
        Rolling fault occur during operation characterized by their vibration signals can be divided into fault wear and surface damage fault. In general, the bearing surface wear failure experience working for a long time, are gradual failure, low extent of its damage. Damage fault tables include fatigue pitting, spalling, cracks, etc., when the damage other components in contact with the bearing point, will produce mutations impulse force, causing the system resonance, causing vibration and noise increases. In normal working conditions at failure is most likely to occur in the form of rolling element or the outer ring raceway point due to withstand cyclic changes of contact stress and fatigue pitting, rolling bearing failure.
        5. Conclusion
        (L) the establishment of a high-speed rolling bearing mechanical model and experimentally verified. The model takes into account the rotation of the inner ring rolling bearing centrifugal expansion deformation and thermal deformation, can accurately predict the bearing contact angle, contact load and stiffness parameters.
        (2) bearing inner ring radial centrifugal force caused by the expansion will change the dynamic characteristics of the bearing. The bearing, the outer ring contact angle increases the amount of expansion of the inner ring of the centrifugal decreases with the increase of the contact load and the amount of expansion of the inner ring of the centrifugal increases.
        (3) For high-speed rolling bearings, rolling elements and maximum contact stress and maximum shear stress of the outer ring are orthogonal with increasing speed increases, the contact fatigue loads damaging the outer ring of the stronger; at the same time, the occurrence of the largest orthogonal Shear stress also increased the depth, location of fatigue crack dark. Change of contact state between the rolling element and the inner with the outer ring opposite.