An oil seal is the customary name for a general seal, which is simply a seal for lubricants. Sealing of equipment is always an important factor in proper operation and safety.
Principle of the lobe pump oil seal.
The oil seal of the lobe pump has a very narrow sealing contact surface (less than 0.5mm) with the rotating shaft with a certain pressure and is sealed under the action of liquid lubrication. As an elastomer seal, the section shape of the oil seal and the hoop spring make the lip have a good following compensation performance to the shaft, so that a good sealing effect can be obtained with a small lip diameter force.
Causes of oil leakage from lobe pump oil seals.
I. Reasons for assembly
1、Deformation of the oil seal after press-fitting due to press-fitting tooling.
2. during assembly, the oil seal passes through the threads or splines, resulting in scratches at the lip.
3、Due to the low roughness of the oil seal bit, the press-fit force is too large, resulting in the failure of the spring or the flip of the lip.
II. Skeleton reasons
Due to oil seal spring material and manufacturing problems, resulting in its performance failure. Spring failure is in the form of: too tight or too loose spring, too loose spring compression force is small, can not achieve the sealing effect, too tight spring compression force is large, the oil seal and rotating shaft with improper cooperation, resulting in abnormal wear of the oil seal, and eventually oil leakage.
III. Reasons for working medium
The working medium is the oil fluid. The choice of oil seal material should consider its compatibility with the oil fluid. Poor compatibility between the two will produce lip swelling, hardening, softening, cracking, etc., and eventually oil leakage will occur.
IV. Causes of lip wear
1, cleanliness problems: casting sand, machining iron chips, oil impurities, etc., a large number of accumulation of oil seal lip parts, abnormal wear occurs when working.
2、The oil seal position is not the same as the rotating shaft, the oil seal is press-fitted and then bias grinding occurs, the lip is abnormally worn.
3. Poor lubrication of lithium base grease at the lip of the oil seal will lead to dry friction, resulting in abnormal wear.
V. Causes of the shaft
1, rotary shaft surface roughness, hardness is unreasonable, the automotive industry is now commonly used roughness of not less than 0.8, and the oil seal with parts will be used high-frequency quenching, hardness of not less than HRC55.
2. Defects on the surface of the rotating shaft, e.g. corrosion, scratches, directional knife marks, etc.