FAG imported bearing seat seal failure reasons and improvement solutions

The FAG imported bearing seat seal improvement plan "multi-stage pressure relief sealing technology" experimental bearing seat seal ring can reduce the lubricating oil leakage by reducing the pressure difference at both ends of the seal in a working environment without large-scale disassembly such as shaft extraction, and at the same time, the residual leaked lubricating oil flows back to the oil tank to achieve the purpose of shaft seal leakage prevention. Specific main technical indicators: The "multi-stage pressure relief sealing technology" experimental bearing seat seal ring can be replaced in the original position of the main shaft without disassembly and there will be no abnormal leakage of lubricating oil within two years of normal operation. The specific research content is as follows.

Sealing material selection and sealing ring performance optimization research

In view of the current shortage of ship working conditions, external environment and zero-diameter sealing rubber rings, a new sealing rubber ring that is more suitable for the intermediate bearing seat of the ship's stern shaft is selected or developed. The sealing material selection research mainly adopts the experimental research method. Select several groups of materials with good elasticity, anti-aging and wear resistance, make sealing rubber rings with wear self-compensation function and reasonable contact surface, carry out targeted wear resistance and sealing performance tests, and select the sealing rubber ring of the imported FAG bearing seat suitable for the middle of the ship's stern shaft. The sealing material technology mainly uses the existing mature technology in China, and improves on this basis as needed to meet the requirements. This is mainly due to the fact that this technology is a special technology and requires a long time of special research. The structure and stress deformation research of the seal mainly adopts the finite element analysis method to provide a basis for structural design. Design analysis and experimental methods are used to reduce the pressure on the friction surface and reduce friction and wear. The wear resistance and life research of the seal also mainly adopts experimental research methods. Through experimental comparison of various sealing materials, a step-by-step optimization method is used to select a suitable bearing seat sealing rubber ring. The selection of sealing sequence, materials and additional equipment depends on different parameters. The pressure and temperature of the medium to be sealed and the diameter and number of revolutions of the shaft to be sealed are important parameters for considering functional safety in design. In order to evaluate, the pressure of the product and the roughness of the sealing surface are often used as evaluation values. Other marginal conditions include the installation environment, product characteristics, such as chemical erosion, agglomeration tendency and solid parts. This plays a fundamental role in the seal design for products with high solid content or mud.

Development of FAG imported bearing seat sealing structure

The sealing effect of single-stage sealing is not ideal, and the lubricating oil leakage of the bearing seat is relatively serious. On the premise of meeting the structural dimensions of the shaft system, it is planned to develop a new concept of the stern shaft intermediate bearing seat sealing system. The new system adopts a two-stage seal plus oil retaining ring structure. The newly added oil retaining ring can partially prevent the lubricating oil in the oil tank from leaking out of the seal along the shaft surface to form leakage. If the first-stage seal leaks, the lubricating oil will enter the cavity between the two seals. Since there is an oil leakage circuit at the bottom of the cavity, the leaked lubricating oil will not form pressure in the cavity, and the second-stage seal will basically not leak oil. It can be seen that the multi-stage pressure relief seal reduces the damage degree of the wearing parts and prolongs the service life. Its seal uses 1 positive pressure rubber ring and 1 negative pressure rubber ring. When the medium passes through the seal, the first-stage rubber seal seals the medium. Even if a small amount of medium passes through the first-stage rubber ring, the second-stage rubber ring will play a role. The external pressure is greater than the pressure inside the shaft seal. Under the action of the internal and external pressure difference, the two-stage seal rings work at the same time to press the rubber ring firmly on the main shaft, which has a sealing effect; when the FAG imported bearing is running, the pressure inside the shaft seal is greater than the atmospheric pressure, and the first-stage seal ring plays a role. The leakage pressure generated by the lubricating oil entering the seal ring oil seal 1 is converted into kinetic energy to work on the rubber ring, and the seal ring oil seal 2 is firmly pressed on the main shaft, which has a sealing effect. Therefore, multi-stage sealing is achieved by using the effect of liquid pressure difference and through secondary sealing elements, rather than relying on packing extrusion or spring action to achieve sealing requirements. In addition, according to the pressure and structural requirements, rubber rings can be added to achieve multi-stage sealing matching, thereby greatly extending the service life of the seal, avoiding frequent replacement of the seal, and achieving a better sealing effect.