The skeleton oil seal is a typical representative of oil seal, and the general term oil seal refers to the skeleton oil seal. The role of the oil seal is to isolate the parts of the transmission that need lubrication from the external environment, so that the lubricant does not leak out. The skeleton is like the reinforcement inside the concrete member, which plays the role of strengthening and enables the oil seal to maintain its shape and tension. According to the structure form, there are single lip skeleton oil seal and double lip skeleton oil seal. The secondary lip of double-lip skeleton oil seal plays the role of dustproof to prevent the dust and impurities from entering the machine. According to the type of skeleton, it can be divided into internal skeleton oil seal, exposed skeleton oil seal and assembled oil seal. According to working condition It can be divided into rotary skeleton oil seal and round-trip skeleton oil seal. Used for gasoline engine crankshaft, diesel engine crankshaft, gearbox, differential, shock absorber, engine, axle and other parts.
Skeleton oil seal structure has three parts: oil seal body, reinforced skeleton and self-tightening spiral spring. The seal body is divided into bottom, waist, edge and sealing lip according to different parts. Usually, the internal diameter of the skeleton oil seal in the free state is smaller than the shaft diameter, i.e. it has a certain amount of "interference". Therefore, after the oil seal is installed into the oil seal seat and shaft, the pressure of the oil seal edge and the contraction force of the self-tightening spiral spring produce a certain radial tightening force on the shaft, and after a period of operation, the pressure will rapidly decrease or even disappear, thus, the spring can compensate the self-tightening force of the oil seal at any time.
Sealing principle: Due to the existence of an oil film controlled by the oil seal edge between the oil seal and the shaft, this oil film has fluid lubrication characteristics. Under the action of liquid surface tension, the stiffness of the oil film just makes the contact end of the oil film and air form a crescent surface, preventing working media leakage, thus realizing the sealing of the rotating shaft. The sealing capacity of the oil seal depends on the thickness of the 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, causing wear of the oil seal and the shaft; if there is no oil film between the sealing lip and the shaft, it will easily cause heat and wear.
Therefore, during installation, some oil must be applied to the seal ring while ensuring that the skeleton oil seal is perpendicular to the shaft centerline. If it is not perpendicular, the seal lip of the oil seal will drain the lubricant from the shaft, which will also lead to excessive wear of the seal lip. In operation, the lubricant in the shell slightly seeps out a little to achieve the most ideal state of forming oil film at the sealing surface.
The role of the skeleton oil seal is generally to isolate the parts of the transmission components that need lubrication from the outgoing parts so that the lubricant does not leak, and is usually used for rotating shafts, a kind of rotating shaft lip seal. The skeleton is like the reinforcement inside the concrete member, which plays the role of strengthening and enables the oil seal to keep its shape and tension. According to the type of skeleton, it can be divided into internal skeleton oil seal, external skeleton oil seal, internal and external exposed skeleton oil seal. Skeleton oil seal is made of high quality nitrile rubber and steel plate, with stable quality and long service life. It is widely used in automobile, motorcycle crankshaft, camshaft, differential, shock absorber, engine, axle, front and rear wheels, etc.
1. Prevent mud, dust, moisture, etc. from invading into the bearings from outside.
2. Limit the leakage of lubricating oil from the bearing. The requirements for oil seal are that the size (inner diameter, outer diameter and thickness) should be in accordance with the regulations; it is required to have proper elasticity, which can jam the shaft properly and play a sealing role; it should be heat resistant, wear resistant, good strength, medium resistant (oil or water, etc.) and long service life.
To use oil seal reasonably, the following points should be noted.
(1) Shaft speed Due to the design and structure, high speed oil seal should be used for high speed shaft and low speed oil seal for low speed shaft, and low speed oil seal cannot be used on high speed shaft and vice versa.
(2) Ambient temperature in the case of high use temperature, polypropylene ester or silicon, fluorine, silicone fluorine rubber should be chosen. And should try to reduce the oil temperature in the oil tank. In the case of using the temperature is too low, should choose to use the cold-resistant rubber.
(3) Pressure General oil seal has poor ability to bear pressure, and the oil seal will be deformed when the pressure is too large. Under the use condition of excessive pressure, pressure-resistant support ring or strengthened pressure-resistant oil seal should be used.
(4) Eccentricity degree on installation If the eccentricity of oil seal and shaft is too large, the seal will become poor, especially when the shaft speed is high. If the eccentricity is too large, the oil seal with "W" section can be used.
(5) The surface finish of the shaft directly affects the service life of the oil seal, that is, if the shaft finish is high, the service life of the oil seal will be long.
(6) Pay attention to a certain amount of lubricant at the lip of the oil seal.
(7) Pay special attention to prevent dust from dipping into the oil seal.Caution:
Caution:
1. Pick up a fixed number of oil seals.
2. From oil seal collection to assembly, must keep clean.
3. Before assembling, make a good inspection of the oil seal, measure whether the size of each part of the skeleton oil seal matches with the size of the shaft and cavity. Before installing the skeleton oil seal, check the size of the shaft diameter against the inner diameter size of the oil seal clearly to match. The size of the cavity should match with the width of the outer diameter of the oil seal. Check whether the lip of the skeleton oil seal is damaged or deformed, and whether the spring is off or rusted. Prevent the oil seal from being put flat during transportation and being affected by external force such as extrusion and impact, and destroy its true roundness.
4. Make good machining inspection procedure before assembly, measure whether the size of cavity and shaft parts are correct, especially the inner chamfer, there can't be slope, the end face of shaft and cavity should be processed smoothly, there is no damage and burr in the chamfer, clean the assembly parts, there can't be burr, sand, iron chips and other debris in the loading place (chamfer) part of the shaft, which will produce irregular damage to the lip of oil seal, it is recommended to use r angle in the chamfering part.
5. In the operation technique, you can feel with your hand whether it is smooth and really round.
6. Don't tear the wrapping paper too early before installing the skeleton oil seal to prevent debris from attaching to the surface of the oil seal and bringing into the work.
7. Before installation, the skeleton oil seal should be coated with lithium ester with molybdenum disulfide added in appropriate amount between the lips to prevent the shaft from causing dry grinding phenomenon to the lips when starting instantly and affecting the overfilling amount of the lips, and should be assembled as soon as possible. The oil seal seat with oil seal installed, if it is not installed immediately, it is recommended to cover it with cloth to prevent foreign matter from attaching to the oil seal. The hand or tool for applying lithium grease must be clean.
8. The skeleton oil seal should be installed flat, no tilting phenomenon. It is recommended to use oil pressure equipment or sleeve tool to install. The pressure should not be too big, and the speed should be even and slow.
9. For the machine where the skeleton oil seal is installed, mark it to facilitate tracking and pay attention to the whole process.
Post time: May-14-2023