主动磁悬浮轴承系统中新型保护轴承的研究

发布时间：2018-08-08 19:58

【摘要】：在磁悬浮轴承系统中，需要一套保护轴承作为磁悬浮轴承失效后转子的临时支撑，保护设备不受损坏。传统保护轴承往往无法支撑超高速转子旋转，且难以承受转子跌落后所带来的振动和冲击。针对传统保护轴承的不足，本文提出了将双层滚珠轴承作为保护轴承来使用，并进行了一系列相关研究。在双层滚珠轴承作为保护轴承使用之前，首先对其力学特性进行了分析。基于拟静力学原理，在考虑轴承所承受的径向载荷、轴向载荷、滚珠自身离心力以及陀螺力矩联合载荷作用下，建立了双层滚珠轴承的力学模型，基于MATLAB平台，编制了单、双层滚珠轴承力学特性分析的计算程序，并研究了相关参数对轴承力学特性的影响，最后搭建了转子—轴承系统试验平台，对仿真结果进行了试验验证。研究结果表明：内外层轴承节径比直接影响到双层滚珠轴承的转速分配；在相同的工作状态下，相对于单层滚珠轴承，双层滚珠轴承具有较小的径向和轴向支撑刚度；外载荷和工作转速影响着单、双层角接触球轴承的滚珠接触角的变化，滚珠的离心力使得滚珠与相应的内、外滚道间的接触角不再相等；外载荷、工作转速、滚珠材料、沟曲率半径和滚珠初始接触角对单、双层角接触球轴承轴向和径向变形均有一定的影响；径向游隙、工作转速和径向载荷对单、双层深沟球轴承的径向变形存在一定的影响。在对双层滚珠轴承力学特性研究的基础上，对转子跌落到弹性阻尼器支撑下的双层滚珠轴承上的动力学响应进行了详细的研究。分别建立了磁悬浮轴承失效前后转子的动力学模型、磁悬浮轴承支撑模型、转子—内圈碰撞模型、滚珠的受力模型以及双层轴承的实时支撑弹性力模型，根据所建立的模型，对在不同参数下，磁悬浮轴承失效后各部分的动力学响应进行仿真计算，并在一个五自由度磁悬浮轴承试验台上进行相关的跌落试验研究。研究结果表明：与传统保护轴承相比，双层滚珠轴承作为保护轴承的使用能有效地降低转子跌落后转子与内圈之间的碰撞力、内层滚珠的最大接触应力和发热量；在实际使用中，可以通过改变内、外层轴承的组合来调节双层轴承受转子跌落冲击后的内、外层滚珠的最大接触应力；为了保证转子跌落后，保护轴承滚珠在许用应力范围内，转子的工作转速及偏心距不能超出其安全区域范围；从降低转子跌落后的碰撞力出发，应该尽量减小转子与保护轴承内圈之间的摩擦系数、选择合适的保护间隙和保护轴承的支撑阻尼；当使用内层为面对面安装的角接触球轴承的双层滚珠轴承作为保护轴承使用时，内层轴承应具有较大滚珠初始接触角和较小轴向预紧力；当选用深沟球轴承组成的双层滚珠轴承作为保护轴承使用时，应尽量选取较大的轴承游隙等级；与铝材相比，选用密度较大的45钢作为双层轴承的中圈转接环材料具有更好的缓冲性能；在保证转子跌落后保护轴承的滚珠最大接触应力不超出最大许用应力范围的前提下，应尽量选择轻薄系列的滚动轴承来组合双层轴承；当将公差环安装在保护轴承系统中时，可以通过改变公差环的材料厚度、突起个数等参数来调整支撑特性，，以提高其工作性能；金属橡胶环的加入能有效地缓冲了转子跌落后的对保护轴承的冲击；公差环和金属橡胶环的减振效果均得到了证明，但从经济性和装配的难易性出发，应优先选择公差环作为保护轴承系统中的弹性阻尼器来使用；保护轴承的破坏性试验证明合适弹性阻尼器支撑下的双层轴承具有更长的寿命，且破坏性试验过程中轴承的损坏形式均为保持架碎裂。
[Abstract]:In the magnetic suspension bearing system, a set of protective bearings is needed as the temporary support of the rotor after the magnetic suspension bearing fails. The protection equipment is not damaged. The traditional protective bearings can not support the rotation of the ultra high speed rotor, and it is difficult to withstand the vibration and shock caused by the fall of the rotor. Double ball bearings are used as protection bearings and a series of related researches have been carried out.
Before the application of double ball bearing as protective bearing, the mechanical characteristics of the double ball bearing were analyzed. Based on the principle of pseudo statics, the mechanical model of the double layer ball bearing was established under the action of radial load, axial load, centrifugal force of ball and gyroscopic moment. Based on the MATLAB platform, the mechanical model of the ball bearing was built. The calculation program of the mechanical characteristics analysis of single and double ball bearings is carried out, and the influence of the related parameters on the mechanical properties of the bearing is studied. Finally, the test platform of the rotor bearing system is built, and the simulation results are tested. The results show that the ratio of the inner and outer bearing to the bearing is directly affected by the speed distribution of the double ball bearing. In the same working state, the double ball bearing has smaller radial and axial support stiffness than the single ball bearing, and the external load and the working speed affect the change of the ball contact angle of the single and double angle contact ball bearings, and the ball's centrifugal force makes the contact angles between the ball and the corresponding inner and outer raceways no longer equal; the external load is not equal. The working speed, the ball material, the radius of the groove curvature and the initial contact angle of the ball have some influence on the axial and radial deformation of the single and double angle contact ball bearings, and the radial clearance, the working speed and the radial load have a certain effect on the radial deformation of the single, double and double deep groove ball bearings.
On the basis of the study of the mechanical characteristics of double ball bearing, the dynamic response of the double ball bearing with the rotor falling to the elastic damper is studied in detail. The dynamic model of the rotor, the support model of the magnetic suspension bearing, the rotor inner ring collision model and the ball bearing are established respectively. The dynamic response of each part after the failure of the magnetic suspension bearing under different parameters is simulated on the basis of the model of the force model and the real time supporting elastic force model of the double deck bearing. The relative drop test is carried out on a five DOF magnetic suspension bearing test platform. The results show that it is with the traditional protection axis. As a protective bearing, the double-layer ball bearing can effectively reduce the collision force between the rotor and the inner ring after the fall of the rotor, the maximum contact stress and the heat of the inner layer ball. In practical use, the inner and outer ball of the outer layer can be adjusted by changing the combination of the inner and outer bearings to adjust the inner layer of the double shaft. Maximum contact stress; in order to ensure the rotor drop and protect the bearing ball in the allowable stress range, the rotor's working speed and eccentricity can not exceed the range of its safety area. From the reduction of the impact force after the fall of the rotor, the friction coefficient between the rotor and the inner ring of the protective bearing should be minimized and the suitable protection clearance should be selected. The support damping of the bearing is protected and the inner layer bearing should have the larger ball initial contact angle and the smaller axial pre tightening force when using the double ball bearing of the angular contact ball bearing with the inner layer to be installed in the face and face as the protective bearing. Select the larger bearing clearance grade; compared with the aluminum, the medium ring connecting material with the 45 steel with a larger density as the double bearing has better cushioning performance, and the rolling shaft of the light series should be selected as far as possible before the maximum contact stress of the ball bearing the ball bearing the bearing is not exceeded the maximum allowable stress range. Bearing combination double deck bearing; when the tolerance ring is installed in the protection bearing system, the supporting characteristics can be adjusted by changing the material thickness of the tolerance ring, the number of projections and other parameters to improve its working performance. The addition of metal rubber rings can effectively buffer the impact of the rotor on the protective bearing after the fall of the rotor; tolerance ring and metal. The damping effect of rubber ring has been proved. But from the difficulty of economy and assembly, the tolerance ring should be chosen as the elastic dampers in the bearing system. The destructive test of the protective bearing proves that the double double bearing with the support of the suitable elastic damper has a longer life and the destructive test process. The bearing is damaged in the form of the cage.
【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH133.3

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