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Common types, installation points, use and precautions of floating oil seal

Source: Time:2019-12-18 09:41:52 frequency:

The floating oil seal was born in the late 1950s and was originally used to replace the rubber oil seal on the bulldozer chassis. The original rubber oil seal was damaged very quickly due to the immersion, wear and corrosion of sediment.
The floating oil seal was born in the late 1950s and was originally used to replace the rubber oil seal on the bulldozer chassis. The original rubber oil seal was damaged very quickly due to the immersion, wear and corrosion of sediment. The floating oil seal is a compact mechanical seal device designed for such a bad working environment, which can prevent the leakage of lubricating oil and the invasion of external mud, sand and other pollutants into the equipment. Its structure is simple, generally composed of a pair of wear-resistant metal rings, floating seal rings and a pair of rubber rings, which are assembled in a special sealing cavity and floating seal seat. It is resistant to pollution, wear, vibration, channeling, swing and impact, reliable in operation, long in service life and convenient in maintenance. Now it has been widely used in various construction machinery and mining machinery. Next, Jinhai industrial and mining machinery will introduce common types of floating oil seal, installation points, use and precautions, wear measurement, failure cause analysis. Come and have a look!

Common types of floating oil seal

1、 The floating oil seal is classified according to the shape of the section of the floating seal ring.

(1) Step type

The working surface of this kind of floating ring is a large diameter spherical surface, with the axial section in the shape of ladder, and the working surface in the shape of concave working surface and the sealing bright band with an included angle of 1 to 2 degrees. When used in pairs, the two spherical surfaces show butterfly shape and the bright band is sealed. The ladder type saves material and labor, and the working face has good lubrication performance and heat dissipation. The disadvantage is that the total width of the working face is narrow, and the use of the hand-held surface is limited.

(2) Bellmouth

The working surface of the floating oil seal is also a large diameter spherical surface with a concave center, while the section is in the shape of a bell mouth, and the seal is completed by its bright band. The advantages of the bell mouth type floating ring are similar to the ladder type, but the disadvantages are that the width of the working face is narrow, but slightly wider than the ladder type, and the service life is slightly better than the ladder type

(3) Wide spherical shape

The working face of this kind of floating oil seal extends to the root of the inner hole all the time, which greatly increases the total width of the working face, thus relatively improves the service life and is more popular. But it is time-consuming and labor-intensive, and the cost is relatively high.

(4) Wide groove type

The working surface of this type of floating oil seal is the same as that of the wide spherical surface, but inside the bright sealing belt, there is a groove with two concentric bags of semicircle oil, which plays the role of oil storage, lubrication and heat dissipation. The disadvantages of this kind of oil seal are time-consuming and high cost. Due to the groove, the total width of the working face is reduced and the service life is shorter than that of the wide spherical surface.

2、 Floating oil seal is classified according to the width of bright band of working face

(1) Narrow bright band type

The width of bright band on the working face of this kind of floating oil seal is only 0.2 ~ 0.3mm, which has the advantage that bright band grinding is simple and time-saving, but the requirements for the concentricity of floating ring are high, and oil leakage will occur when the concentricity is out of tolerance in the work.

(2) Wide bright band type

This kind of floating oil seal has a wide width of bright band, which can reach 1.5 ~ 2.5mm. The advantage is that the concentricity requirements of floating ring parts are not high when they are assembled in time, and the sealing performance is good, but grinding bright band takes time and effort.

3、 Floating oil seal is classified according to the material and manufacturing process of floating ring

(1) Precision casting

Most of the sealing rings are made of high chromium molybdenum alloy cast iron, which are precisely cast by paraffin shell mold. The hardness of the blank is (40-50) HRC, and the surface hardness of the finished product can reach (65-72) HRC. The roughness of the working surface is divided into 0.2-0.4um. Generally, when the R value is 0.1um, the service life can reach 4000-6000 hours. There are many manufacturing processes for this material, which are adopted by many manufacturers.

(2) Mechanical die casting

This kind of floating seal ring is made of alloy cast iron by die casting. The metallographic structure of the finished product is relatively fine, but the cost is slightly higher. The roughness r value of the working surface is 0.2-0.4um, the bright band r value is 0.09-0.15um, and the service life is about 4000-6000h.

(3) Powder metallurgy hot satin

This kind of sealing ring is mainly made of powder metallurgy by high temperature hot forging. The R value of working surface roughness is generally 0.4um, the surface hardness of finished product is (40-62) HRC, and the service life is about 2000-4000 hours.

(4) Thermal spray type.

The base of sealing ring is common cast iron, which is made by grinding and spraying 0.05 ~ 0.20 mm high chromium molybdenum powder on the working surface. The surface hardness can reach (55-65) HRC, and the service life can reach 4000-6000 hours. This kind of process saves rare metals, but the productivity is low and the cost is high due to the restriction of equipment.

Installation points of floating oil seal

1. Whether the floating oil seal is installed correctly has a great influence on its good use. Take A-type floating oil seal as an example, first of all, make preparations. Clean the equipment and floating seal seat to ensure there is no burr, impurity, oil stain, etc. For the old equipment, first use a scraper to remove the dirt and rust on the surface of the chamber of the floating seal seat, then use a non oil based cleaning agent to clean it, and finally use a silk cloth or chamois to clean it. Check whether the floating oil seal is in good condition and clean, whether the sealing surface is damaged or scratched, etc., and grind and repair if necessary. The floating seal ring shall be handled carefully to prevent damage or deformation. Composite installation chamber size and assembly size. Put the O-ring on the bottom of the conical surface of the back of the floating seal ring and stretch it properly to avoid distortion or uneven stretching.

2. During installation, in order to ensure the installation is accurate and in place, it is required to install horizontally and downward to avoid tilting, vertical or upside down. As shown in the figure, it is recommended to use the installation tool. Put the installation tool on the outer circle of the floating seal ring, align the O-ring horizontally with the inlet of the floating seal seat chamber, and steadily press the installation tool step by step. The installation tool keeps the O-ring at the bottom of the conical surface on the back of the floating seal ring to keep its outer diameter at a minimum. 

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