| Bearing is such an important component of rotation pair that its strength, resistance to fatigue failure, normal life and other properties play a decisive role in the performance of a rotational behavior. Thus all the performance parameters of a bearing must be tested. At present, the domestic bearing testing-rigs mainly depend on mechanical loading and electrical loading. However, with the development of industrial technology, the performance requirements on the bearing become higher and higher, the same is true on the bearing testing rigs. In many situations, however, these two common methods cannot meet the testing requirements. Fortunately, the hydraulic technology enables hydraulic loading manner to satisfy the new testing requirements and it has been becoming a new proposal in bearing testing-rigs. Therefore, it is necessary to study the hydraulic load bearing testing-rigs.According to the bearing characteristics and testing requirements, this article studies the composition principle, the adjustment and the operating characteristics of the hydraulic loading system.1.To analyze the characteristics of the bearing condition, and to make clear of the testing requirements of the bearing tested. In order to make clear of the conditions and requirements of the testing systems, the working characteristics and performance requirements of aircraft bearings have been introduced in advance. While the testing rig is designed for bearings of aero, and aircraft bearings, both their service life and performance need to be longer and stronger than those of ordinary bearings.2. To design the proposal of hydraulic loading system according to the test requirements. Bearing hydraulic loading system consists of two parts: the loading circuit and driving circuit. Loading circuit mainly load on the bearing from different directions to simulate the actual working conditions. The size of the loading force has to be adjusted by the electronic proportional relief valve on real-time. The system can get a wide range of loading capacity and fast response, it also works accurately and operates easily; driving circuit controls the speed of the bearing using the characteristics that hydraulic drive can get variable speed, good stability when changing direction and driving force is very large, so the trial system can fully simulate the actual working conditions of the bearing. Thus the bearing is tested dynamically.3. To analyze matching features and the main work characteristics of the hydraulic loading system. To get accurate performance of the bearing test, the hydraulic system must be designed reasonable in the aspect of matching, such as the pump - motor matching which is important to make sure the speed of the bearing to meet the test requirements; the size of the control valves and cylinder diameter must be chosen to ensure the scope of the loading force to meet the test conditions. Meanwhile, working characteristics of the adjusting method of the proportional relief valve, control precision of the loading force and control precision of the speed are analyzed and calculated in detail.4. To use AMEsim graphical simulation software to establish the dynamic simulate model of the hydraulic system. The system is designed to determine the parameters which are brought into the simulation model of the system. Loading and driving characteristics are researched and analyzed in-depth and verify the correctness of theoretical analysis.5. Finally, to test hydraulic loading testing rig and to verify the correctness of the theoretical calculation and the simulation analysis of the system. The present study shows that it can simulate the loading on the bearings with high control precision, easy operation and the result is favorable. |
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