| The one of main failure form of rolling bearing is rolling contact fatigue, and the fatigue life test is a major means to evaluate bearing material performance. Therefore, it is of great importance to research and develop a test device which can simulate the real working condition of bearing saccurately, and it can provide reliable data support for developing high performance bearing material. The main work of the paper is as follows:(1) Structural design is done for the rolling contact fatigue testing machine. Through functional analysis, the machine can be separated into five parts: a loading system, a spindle system, a lubrication system, a measurement and control system and an electrical control system. In the loading system, a new type of leverage servo loading system is designed combining with lever loading principle and servo control technology, It can ensure the loading accuracy and the cost of the testing machine; In spindle system, the structural designs of spindle components and spindle end are finished respectively, and the selection of spindle motor and belt drive is given; In lubrication system, structural design is done for the lubricating devices; In the process of designing the measurement and control system function, different sensors are selected according to the needed test data; In the function design of electrical control system, the major loops of the system power supply, the spindle motor and the servo motor are designed respectively. According to the test requirements, the function design requirements are put forward for the other parts of the electrical control system, which can facilitate the test operation.(2) The servo loading system is considered as the series of servo drive system and mechanical transmission system. The mathematical models of servo drive system and mechanical transmission system are established respectively. The establishment of a complete mathematical model of servo loading system is accomplished based on the PID controller.(3) Simulink Simulation model of the servo loading system is built, and the dynamic characteristics simulation analysis of the system simulation model is conducted,at the same time, the influence of different mechanical parameters(the moment of inertia,equivalent damping and stiffness) on the system dynamic characteristic is studied.Meanwhile, the reasonable value range of mechanical parameters of the servo loading system is obtained, which provides data support for further optimization of the loading system parameters.(4) The testing machine is debugged and ran to meet the design requirements of each system function, and the servo loading system is tested to verify the correctness and reliability of the simulation results. |
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