Abstract: The problem of oil leakage has always been one of the main factors affecting the use of the reducer of the rolling mill. In the maintenance work of the rolling equipment of Xuan Steel, how to prevent and deal with the oil leakage of the reducer has always been one of the key contents of the maintenance work. The article combines the actual work Based on experience, the causes and countermeasures of oil leakage of the reducer are sorted out to deal with the actual problems in production and play a role in promoting this work.

　　 Keywords: reducer; oil leakage; joint surface; oil seal
　　 Introduction
　　Roller reducer is a key equipment in steel rolling production, but the actual operation of the reducer basically has light or heavy oil leakage problem, oil leakage problem has always been the main factor affecting the normal use of the reducer. The leakage oil of the reducer not only wastes a lot of lubricating oil, causing economic losses and polluting the environment, but also threatens the safe use of the equipment and the smooth progress of production. In serious cases, it will also cause the internal gears and bearings of the reducer to be too low due to lack of oil. To sufficient lubrication, the tooth surface wear is increased and the bearings are burned out, which leads to equipment accidents.
　　1　 Reason analysis of reducer oil leakage
　　The parts of the reducer oil leakage are mainly concentrated in the three parts of the observation hole, the box joint surface and the input and output shaft holes. There are many reasons that can cause the reducer oil leakage, which can be summarized into the following points:
　　 1.1 Oil leakage at the joint surface
The main reason for the oil leakage at the joint surface is that the flatness of the joint surface during manufacturing does not meet the design requirements. At the same time, the uneven tightening torque of the fastening bolts during the later installation and the thermal deformation of the components will cause oil leakage at the joint surface .
　　1.2 Oil leakage at input and output
(1) The oil seal is damaged and there are two reasons for the damage of the oil seal. One is the assembly reason. When the oil seal is matched, the coaxiality control of the outer diameter of the oil seal and the inner diameter of the end cap is unqualified, so that during the rotation of the shaft , Will cause wear between the oil seal and the end cover, resulting in increased temperature. Temperature is a key condition for oil seal damage. Long-term high-speed operation will increase the wear between the oil seal and the shaft, resulting in long-term high temperature, which will cause the oil seal The carbonization of the material causes elastic failure until the oil leakage is damaged; in another case, there is friction between the outer end surface of the end cap with an oil seal and the connected shaft. With operation, the temperature of the end cap will increase, As a result, the temperature of the oil seal rises. Once this happens, due to the large amount of heat generated in a short time, the oil seal lip will be directly deformed by heat, weakening the sealing effect.
(2) Shaft wear, after long-term operation of the reducer, it will inevitably cause wear on the outer surface of the shaft where the oil seal is installed. This changes the tolerance fit of the equipment installation, and slight wear will affect the skeleton oil seal to a certain extent. The serious effect of the sealing effect is the complete failure of the oil seal. At the same time, the roughness of the surface of the reducer shaft will also affect the wear of the oil seal. It should be controlled on the basis that the requirements of the roughness of the lubricating oil film can be established, and the roughness of the reducer shaft should be reduced as much as possible to maintain the good sealing performance of the oil seal.
　　1.3 Too much oil
The amount of oil injection inside the reducer should be strictly in accordance with the standard. Excessive oil injection will increase the stirring effect of the rotating parts such as the internal gears of the reducer on the oil, resulting in the splash of lubricating oil inside the reducer, which will increase the oil seal and The accumulation of lubricating oil at the joint surface increases the probability of leakage of lubricating oil. In addition, excessive oil volume will also affect heat dissipation, resulting in an increase in operating temperature.
　　1.4 Oil leakage at the end cap
　　The precision control of the bearing hole of the reducer is not qualified and the bearing assembly is not in place, which will result in a poor coordination between the outer ring of the bearing and the inner ring of the bearing hole, so that the lubricant will leak from the gap between the two.
　　1.5 Leakage caused by poor ventilation
The working environment of the reducer of the rolling mill is bad, and the probability of the blocker of the ventilator is relatively large. Once the ventilator is blocked, the gas inside the reducer cannot be discharged normally, and it will accumulate inside the reducer to form a certain air pressure environment. As the temperature rises, the pressure inside the reducer becomes higher and higher, and the lubricating oil will leak out from each gap of the reducer under the pressure.
　　2　Prevention of oil leakage of reducer
　　 2.1 Reasonable assembly
The installation specifications must be strictly implemented when installing the relevant parts of the reducer. Brutal operations should be avoided, especially the assembly of each joint surface. Before assembly, the dust and oil sludge on the surface of the joint surface must be wiped clean with a special cleaner. Afterwards, apply sealant evenly on the joint surface. Special care should be taken here that the sealant cannot be applied to the bolt holes to ensure a good sealing effect of the joint surface after assembly. In addition, diagonal tightening should be used when tightening the joint surface bolts In a fixed way, control the tightening torque of each bolt to make the contact surface smooth and uniform.
　　2.2 Return oil in time
The bearing should be prevented from being thrown on the shaft seal during the operation of the gear. The excess oil can accumulate in the shaft seal, resulting in oil leakage caused by the increase in local oil pressure. The structure should be reasonably designed to remove the excess oil at the shaft seal and the oil return groove. Return to the box in time. When designing the reducer mechanism, an oil return groove that flows to the box body should be added from the lower edge of the bearing housing, and a gap must be reserved at the end of the end cover. The position of the gap should be aligned with the oil return groove. In order to ensure that excess lubricating oil flows into the oil return tank from the gap, and finally flows back to the tank body along the oil return tank.
　　2.3 Correctly select the oil seal
The choice of oil seal should be based on the principle of strong oil resistance, heat resistance and oxidation resistance. At the same time, the selected oil seal should also have good sealability and dustproofness. Choose the best state according to the actual environment of the use site. At the same time, the wear resistance of the joint part of the oil seal with the shaft should be considered. The part corresponding to the oil seal on the shaft should be heat treated in advance to increase the hardness of the part and increase the wear resistance.
　　 2.4 Reducing the cabinet body and shaft ground repair
When the gearbox body is deformed or the size of the bearing hole is changed, the box body needs to be reworked and repaired in time. When repairing, one of the basic surfaces of the gearbox should be corrected first, and then the upper and lower boxes are approved according to the reference surface The minimum processing size of the body grinding process, and the upper and lower boxes are processed according to this size. The processing of the bearing hole needs to be carried out after the box is combined, so as to improve the processing accuracy of the bearing hole. Using this method can overcome the problem of deformation of the box body on the basis of avoiding the problem of dimensional tolerance. If only the bearing hole needs to be processed, and the size deviation of the bearing hole is not very large, the pad method can be used to repair according to the actual amount of wear. For the input shaft and output shaft surface roughness greater than the design standard, you can use a grinder to grind, so that the surface roughness meets the qualified requirements.
　　3　 Conclusion
In the actual use process, oil leakage in the reducer of the rolling mill is a relatively common problem. This problem has always troubled the maintenance personnel and is difficult to completely eliminate. Through the above analysis, it can be known that the oil leakage of the reducer is caused by a variety of Comprehensive problems caused by reasons, only to find the cause of oil leakage and take corrective measures can effectively deal with the problem of reducer oil leakage. As a maintenance person, you should be familiar with the performance of the components of the reducer you are maintaining, and timely repair the parts that may have lubricant leakage to avoid the expansion of the oil leakage problem. This can not only save a lot of lubricants, but also effectively improve the deceleration. The service life of the machine reduces equipment failures, thereby promoting the smooth development of production.
  references
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Source: "Science and Technology Innovation and Application" 2015 Issue 26