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Analysis of seal leakage of roller
Class:Industry News Pubdate:2021-01-27 14:11:40 Browse:0 [Back]

       Roller is an important load-bearing part of crawler construction machinery (commonly known as "lower roller"), which is composed of roller body, supporting shaft, left and right supporting seat and sealing components. The supporting shaft is fixed on the platform frame through the left and right supporting seats. There is a pressed shaft sleeve in the wheel body to rotate with the supporting shaft. A sealing component is installed between the rotating wheel body and the fixed left and right supporting seats to keep the lubricating oil seal between the supporting shaft and the shaft sleeve. The sealing assembly is composed of a pair of double conical metal sealing rings and two butadiene rubber fixed compression rings. The rubber ring is respectively installed in the sealing seat mouth of the wheel body and the support seat. Because the metal sealing ring bears the extrusion support of the rubber ring and makes its annular blade belt closely mesh in rotation, the seal belongs to the floating seal type.

       Analysis of seal leakage of roller

       Roller is an important load-bearing part of crawler construction machinery (commonly known as "lower roller"), which is composed of roller body, supporting shaft, left and right supporting seat and sealing components. The supporting shaft is fixed on the platform frame through the left and right supporting seats. There is a pressed shaft sleeve in the wheel body to rotate with the supporting shaft. A sealing component is installed between the rotating wheel body and the fixed left and right supporting seats to keep the lubricating oil seal between the supporting shaft and the shaft sleeve. The sealing assembly is composed of a pair of double conical metal sealing rings and two butadiene rubber fixed compression rings. The rubber ring is respectively installed in the sealing seat mouth of the wheel body and the support seat.        Because the metal sealing ring bears the extrusion support of the rubber ring and makes its annular blade belt closely mesh in rotation, the seal belongs to the floating seal type.

       We think that the small taper angle of the floating oil seal is beneficial to reduce the runout of the engagement ring of the floating seal ring caused by the external impact of the roller, improve the axial force on the engagement surface of the seal and keep the axial force from changing sharply due to the increase of the axial clearance of the system. However, the smaller the sealing cone angle is, the rubber ring is prone to skew on the cone surface during the assembly of the supporting wheel. In addition, the compression of the sealing seat mouth on the rubber ring is increased, which makes it more difficult to ensure the correct position of the sealing meshing edge belt in the assembly. By analyzing the relevant data of some international companies, it is known that the taper angle of floating oil seal becomes smaller, which is the development trend in design.

       Based on the above analysis, we have taken two measures

       (L) the original design parameters such as the taper of the floating oil seal ring and the taper angle of the rubber ring seat remain unchanged, and the compression of the rubber ring can be appropriately changed with simple design changes.

       (2) improve the assembly process and add special tools to ensure the correct position of the floating oil seal rubber ring on the conical surface of the sealing ring and the correct position of its installation into the sealing seat, so as to ensure the correct engagement of the cutting edges of the two sealing rings.

       After strict assembly according to the above measures, no leakage was found in both test and installation.

       In our opinion, in order to improve the service life of the floating seal assembly of the supporting wheel in the walking mechanism of construction machinery, foreign companies will reduce the taper angle of the seal ring and the taper angle of the rubber ring seat, which is beneficial both in theory and in practice. However, if they can not ensure the accurate assembly in place in the manufacturing, it will backfire.

       If the assembly of the floating seal assembly is wrong, although the factory needs to do the air tightness inspection in the static original position, due to the elastic effect of the rubber ring, the air tightness inspection pressure can not be detected when it does not reach a certain value, and there will be no leakage after oil injection. After a certain period of work, due to the friction of various parts and the pressure in the inner cavity rising to a certain value, the rotating meshing part will be damaged due to the friction of the rubber ring The elastic force makes the axial contact force of the blade belt at this point smaller, and there will be intermittent leakage; if the blade belt stops rotating in this case, the leakage at the meshing point is not instantaneous, but serious leakage, and the leakage will not stop until the pressure in the inner cavity drops to a certain value and the elastic force of the rubber ring reaches a new balance.

       Under the condition of incorrect assembly, the friction and wear of the local cutting edge will be intensified due to the pressure, and the heat will be generated rapidly, which will reduce the viscosity of the lubricating oil and aggravate the wear of each rotating pair.

       The above analysis shows that a high-quality component, in addition to design, high-quality parts processing, the correct assembly is very important.

(source: Internet)