Skeleton oil seal is a typical representative of oil seal. Generally speaking, oil seal refers to framework oil seal. The function of oil seal is to isolate the parts that need to be lubricated in the transmission parts and the output parts, so as not to let the lubricating oil leak. The skeleton is like the steel bar in the concrete component, which plays a reinforcing role and keeps the shape and tension of the oil seal.

According to the structure, it can be divided into single lip framework oil seal and double lip framework oil seal. The secondary lip of double lip framework oil seal plays a dust-proof role to prevent external dust and impurities from entering into the machine. According to the framework type, it can be divided into inner framework oil seal, exposed framework oil seal and assembled oil seal. According to the working conditions, it can be divided into rotating framework oil seal and reciprocating framework oil seal. For gasoline engine crankshaft, diesel engine crankshaft, gearbox, differential, shock absorber, engine, axle and other parts.

The framework oil seal structure consists of three parts: oil seal body, reinforced framework and self tightening spiral spring. According to different parts, the sealing body is divided into bottom, waist frame oil seal structure drawing part, edge and sealing lip, etc. Generally, the inner diameter of the framework oil seal in free state is smaller than that of the shaft diameter, that is, it has a certain amount of interference. Therefore, when the oil is sealed into the oil seal seat and shaft, the pressure of the oil seal edge and the contraction force of the self tightening spiral spring will produce a certain radial tightening force on the shaft. After a period of operation, the pressure will rapidly decrease or even disappear. Therefore, the spring can compensate the self tightening force of the oil seal at any time.

Sealing principle of framework oil seal: because there is an oil film controlled by oil seal edge between oil seal and shaft, the oil film has fluid lubrication characteristics.

Under the action of framework oil seal, the rigidity of oil film just makes the contact end of oil film and air form a crescent surface, which prevents the leakage of working medium, thus realizing the sealing of rotating shaft. The sealing capacity of oil seal depends on the thickness of oil film on the sealing surface. If the thickness is too large, the oil seal will leak; if the thickness is too small, dry friction may occur, which will cause wear of oil seal and shaft; if there is no oil film between sealing lip and shaft, it is easy to cause heat and wear. Therefore, during installation, some oil must be applied on the sealing ring, and the skeleton oil seal must be vertical to the axis line. If not, the sealing lip of the oil seal will drain the lubricating oil from the shaft, which will lead to excessive wear of the sealing lip. In operation, the lubricant in the shell seeps a little bit to form an oil film on the sealing surface.

The role of the framework oil seal is to isolate the parts that need lubrication in the transmission parts from the output parts, so as to prevent the leakage of lubricating oil. It is usually used for the rotating shaft and is a kind of rotary shaft lip seal.

The skeleton is like the steel bar in the concrete component, which plays a reinforcing role and keeps the shape and tension of the oil seal. According to the framework type, it can be divided into inner framework oil seal, outer framework oil seal and inner and outer exposed framework oil seal. The framework oil seal is made of high quality nitrile rubber and steel plate, with stable quality and long service life. Widely used in automobile, motorcycle crankshaft, camshaft, differential, shock absorber, engine, axle, front and rear wheels and other parts.

1. Prevent sand, dust, water vapor from outside into the bearing;

2. Limit the leakage of lubricating oil in the bearing. The requirements for oil seal are that the size (inner diameter, outer diameter and thickness) of oil seal should meet the requirements; it should have appropriate elasticity, be able to properly block the shaft and play a sealing role; it should be heat-resistant, wear-resistant, strong, medium resistant (oil or water, etc.) and have a long service life.

The following points should be paid attention to when using oil seal reasonably

(1) Due to the design and structure of the shaft, high speed oil seal should be used for high speed shaft, and low speed oil seal should be used for low speed shaft. Low speed oil seal should not be used for high speed shaft, and vice versa.

(2) In the case of higher ambient temperature, polypropylene ester or silicon, fluorine and silicon fluorine rubber should be selected. Try to reduce the oil temperature in the oil tank. When the temperature is too low, cold resistant rubber should be selected.

(3) The oil seal with general pressure has poor bearing capacity, and the oil seal will deform when the pressure is too high. Under the condition of excessive pressure

Pressure bearing ring or reinforced pressure oil seal shall be used.

(4) If the eccentricity of oil seal and shaft is too large, the sealing performance will be poor, especially when the shaft speed is high. If the eccentricity is too large, the oil seal with W-shaped section can be used.

(5) The surface finish of the shaft directly affects the service life of the oil seal, that is to say, if the surface finish of the shaft is high, the service life of the oil seal will be

Long.

(6) Pay attention to the oil seal lip should have a certain amount of lubricating oil.

(7) Pay special attention to prevent dust from getting into oil seal.