Rolling noise analysis of NTN bearings

    The rolling sound is due to the rolling of the rolling elements in the raceway when the NTN bearing rotates to excite a smooth and continuous noise, which only attracts attention when its sound pressure level or tone is extremely large. In fact, the sound energy excited by the raceway sound is limited. For example, under normal conditions, the quality of the 6203NTN bearing raceway is 25~27dB. This type of noise is the most typical of single row deep groove ball NTN bearings that can withstand radial loads. It has the following characteristics: a. noise and vibration are random; b. vibration frequency is above 1 kHz; c. no matter how the speed changes, noise master The frequency is almost constant and the sound pressure level increases with the increase of the rotational speed; d. When the radial clearance increases, the sound pressure level increases sharply; e. NTN bearing seat increases rigidity, the total sound pressure level is lower, even the rotational speed When the temperature rises, the total sound pressure level also increases little; f. The higher the viscosity of the lubricant, the lower the sound pressure level, but for grease lubrication, the viscosity and shape of the soap fiber can affect the noise value.
The rolling sound is caused by the natural vibration of the ferrule after the load. Due to the elastic contact of the ferrule and the rolling body, a nonlinear vibration system is formed. When the lubrication or machining accuracy is not high, the natural vibration associated with this elastic characteristic is excited, and when it is transmitted to the air, it becomes noise. It is well known that even with the most advanced manufacturing techniques used to process NTN bearing parts, there are always small geometric errors in the working surface, which causes small fluctuations between the raceway and the rolling elements to excite the natural vibration of the vibration system.
Although the rolling noise of the NTN bearing is unavoidable, in the high-precision machining of the working surface of the part, the NTN bearing is correctly selected and the NTN bearing is accurately used to reduce noise and vibration.

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INA bearing precision detection and adjustment

      Due to the large size and heavy weight of the hydraulic machine, it is limited by various processing conditions such as casting, forging, cutting and assembly. Therefore, the working precision of the press itself cannot be completely guaranteed by the machining itself, but must be assembled. The adjustments in it to achieve its various accuracy indicators.
      The adjustment is based on the specific requirements of the INA bearing accuracy test, and the accuracy and stability of the accuracy is ensured by the pre-tightening and anti-loose means and measures associated with it. Hydraulic presses used in various industries have different requirements for their work accuracy due to their different uses, and different industry standards are also used in manufacturing. In the same industry, the accuracy required cannot be the same due to different production products. Therefore, in the same industry standard, according to different working conditions, it is divided into several levels and corresponding to each precision index. In the factory production, the technical department shall prepare the inspection outline and the test run syllabus according to the accuracy standard of the production press, and issue the relevant departments as the guiding documents, which stipulate the test methods and corresponding data of the relevant items and parameters, as the standard for installation adjustment and inspection and acceptance. .
      It generally includes precision items that need to be adjusted during assembly of the INA bearing. For example, in the hydraulic press, the level of the table, the deviation of the column spacing, the flatness of the table and the movable table, the verticality of the upper and lower beams connected to the column, the parallelism between the tables, and the working distance of the main cylinder during the working stroke The verticality of the table, the contact ratio of the inner and outer nut fitting surfaces of the column and the upper and lower beams, and the like. The process and results of INA bearing precision adjustment and testing must be approved by the full-time staff. The tools and tooling required for the inspection and adjustment process are designed by the professional craftsmen in the production process and programmed into the production process as planned. The inspection outline and inspection adjustment operations are omitted.

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