Analysis of the leakage and sealing of rolling equipment Zhou Liangqing (the leakage of the second rolling mill of Sanming Iron and Steel Plant of Fujian Province).
Key words new structure new materials cure leaks 1 rolling mill mainframe equipment lubrication and leakage overview Fujian Sanming Iron and Steel Plant wire workshop annual rolling Q235 wire 180,000 tons, seven main column is the key equipment for rolling materials, the gearbox of each machine The distribution box and the herringbone gear base are all lubricated with thin oil circulation. Since the host device is a product of the 1970s, the manufacturing precision is not high, and the seal design is also insufficient, and there are different degrees of oil leakage. Especially the protruding end of the rotating shaft, the oil leakage of the upper and lower casings is the most serious. In 1997, the mechanical oil consumption of the tonnage reached 0.65kg, which not only increased the cost of the tonnage, but also exceeded the oil content of the wastewater. Therefore, the management of oil leakage from the host equipment is a major event for equipment managers and technicians to deal with the leakage of lubricating oil in rolling mill equipment. It has long been regarded as a difficult problem. To completely cure it, first find out the location of the oil spill, distinguish the type of oil spill, and analyze the cause of the oil spill. Then, according to the type of oil spill, a feasible sealing scheme is formulated, and the treatment can be carried out in stages and in batches in order to achieve the goal of completely eradicating oil leakage.
2 analysis of the cause of oil leakage, the development and implementation of the method of sealing 2.1 to distinguish the type of oil leakage from the shaft extension end oil leakage. The gear leakage of the shaft, the distribution box, and the shaft extension of the herringbone gear seat are classified into one category.
The part is shaped to leak oil. The parting surfaces of the upper and lower cases of the reduction gear box, the distribution box and the herringbone gear seat are classified into the influence of one type of bearing bush clearance on the sealing and the treatment.
Oil leakage caused by pressure difference between the inside and outside of the gearbox and distribution box strengthens the management of lubrication and sealing to prevent unnecessary oil leakage.
2.2 Analysis of the cause of oil leakage, the development and implementation of the sealing method for the analysis of the cause of oil leakage at the shaft extension end, the development and implementation of the sealing method of the gearbox, the distribution box and the shaft extension end seal structure of the herringbone gear seat, in the rolling bearing or bearing bush An oil slinger is arranged between the end caps of the box. It can only block a part of the lubricating oil splashed from the bearing, and the other part of the lubricating oil splashes to the inside of the through cover, and leaks out along the gap of the through cover as the shaft rotates. The plastic on the cover can only slow down the leakage of the lubricating oil, especially when the rubber is worn, the oil leakage is more serious. Through analysis, the structure of the oil ring and the cover is improved, and the non-contact seal is used. Structure, as shown, the oil ring is changed to the oil pan, and the inner side of the cover is changed to the inner side of the oil return groove. When the bearing rotates, most of the lubricant measured by the fly is sucked into the box, and a small amount of lubricating oil splashes into the cover. The inner side can flow into the tank along the oil return groove, effectively preventing the leakage of the lubricating oil, and the rubber on the outer side of the through cover mainly prevents the impurities (water, dust) from entering the tank. The method of demonstrating the effective leakage of the oil leakage through the practice shows that the gearbox, the distribution box, the finger-type surface of the herringbone gear box body are analyzed, and the sealing method, the distribution box, the herringbone gear box body parting surface are formulated and implemented. The surface roughness of the machined surface is 5, and the surface of the upper and lower parts of the box needs to be filled with sealing material when the surface of the upper and lower parts is assembled. Otherwise, the lubricating oil in the box will leak out from the parting surface. This is a common oil leakage phenomenon. There are two requirements for the parting surface with assembly accuracy requirements. First, the filling surface does not produce a thickness after filling the sealing material. Second, the filled sealing material can effectively prevent the lubricating oil for a long time. Leakage to the outside of the box is usually filled with "lacquer" or "7903 lubrication sealant" on the parting surface. When using "lacquer", the parting surface of the upper and lower cases can be quickly glued together, and the thickness is not thick. The disadvantage is that under the action of the impact force of the rolling steel, when the pre-tightening force of the coupling bolt of the parting surface is insufficient, the parting surface generates minute separation and vibration. At this point, the cured lacquer cracks, leaving the parting surface, loses the sealing effect, the oil will leak out and the "7903 lubricating oil sealant" is soft, although it does not produce the thickness of the pad, but the lubrication in the box Under the impact of oil, it gradually melts, especially the unevenness of the parting surface of the box melts faster. After a period of use, the lubricating oil in the box penetrates outside the box to analyze the oil leakage of the parting surface. The reason is that two kinds of effective squeezing oil pan and type apron composite sealing structure are adopted. The box parting surface milling belt is embedded in the groove. The new type or the new processing spare box, the parting surface of the lower box Milling a groove-shaped groove, the size of the rectangular groove is determined by the oil-resistant "O-type tape specification. Generally Y5mm~Y8mm, when the box size is large, take a larger specification of the O-belt. Otherwise, take a small size. “When the O-belt is assembled, it is only necessary to put the oil-resistant O-belt into the groove to join the box. Under the action of the upper and lower casings, the belt is elastically deformed, and the elastic force acts on the upper, Lower case, effectively preventing the lubricating oil in the box from leaking out of the parting face
The second is the gear box that has been installed at the production site. It is not convenient to remove the machining groove and seal it with the “O-belt. For such a box parting surface, it can be used as a filling material for the Loctite 587 silicone rubber. The advantage of the glue is: soft, oil-resistant, non-aging, long-term elastic state, no parting surface pad thickness, ensuring bearing matching precision. When using, the glue is extruded on the lower box parting surface by a Y2mm ~Y3mm ring tape, its position can be found in the place where the rectangular groove is milled. When the parting surface is large and rough, the diameter can be selected to be larger. Otherwise, the diameter can be selected to be smaller, and then the box can be locked by the upper and lower box bolts. If the upper box does not have assembly accuracy requirements (not used as the upper and lower boxes for the bearing fit), a Y3mm~Y5mm ring tape can be extruded on the parting surface, which can achieve a fairly good sealing effect after the box is assembled. The influence of the bearing bush clearance on the seal and the bearing for the herringbone gear seat of the rough rolling and medium rolling mill are generally alloy tiles, and the clearance of the bearing bush has a great influence on the sealing. After the use of the newly installed bearing bush after a period of use, the shaft and watt Wear occurs. When the top clearance of the shaft and the tile becomes larger than 2d/1000mm, the shaft will jump in the tile. The larger the gap, the more the jump will be, the more the shaft will jump, and the seal at the protruding end will produce an instantaneous gap. The lubricating oil will leak out to the outside of the box along the gap. In this case, it is necessary to open the box to adjust the bearing bush clearance, so that the gap between the shaft and the tile is controlled within the range of 1000mm 1.5d~1.8d, and the shaft jump can be eliminated. The leakage naturally disappears and the oil is resistant. The O-type belt is used in the case of the part-type surface sealing reduction gear box, the pressure difference between the inside and outside of the distribution box to generate oil leakage and the control of the reduction gear box, the distribution box in the running process, the lubricating oil in the gear mixing box, the oil The temperature rises, and the friction of the meshing process of the second gear also causes the oil temperature to rise, so that the temperature inside the tank is higher than the outside temperature. That is, the air pressure in the box is greater than the air pressure outside the box. In order to balance this pressure difference, a "breathable cap" is placed on the upper cover at the time of design.
However, during the inspection and maintenance process, the "breathable cap" is often forgotten to be cleaned, blocked by the sludge, and does not play a role of ventilation. At this time, the air pressure inside the box is greater than the air pressure outside the box, and the lubricating oil will seep from the weakest part of the seal. Leaking out of the box, the solution is very simple, as long as the annual maintenance, do not forget to clean the breathable cap, so that it is normal ventilation, strengthen the lubrication and sealing management, eliminate unnecessary oil leakage, oil pumping, learning lubrication knowledge and operating procedures, master lubrication The system's oil pressure control, oil quantity adjustment, oil temperature control, oil quality inspection, to prevent artificial lubrication leakage.
Establish a sealing point inspection system, regularly check the sealing situation, find signs of leakage in time to adjust or replace the seals, and keep the entire lubrication system in a leak-free state.
After the analysis and treatment of the above five aspects, the oil leakage of the workshop equipment has been cured, and certain benefits have been achieved. 3 The benefits obtained have reduced the consumption of lubricating oil. In 1998, the rolled wire was 180,000 tons, and the mechanical fuel consumption was 48 tons (0.267 kilograms). Material), halving the oil consumption in 1997, saving 15 million yuan to create a civilized production environment. It turned out that due to the existence of oil spills, the equipment was surrounded by oil stains. When the red steel fell to the occasion, it caused fire, and it also brought unsafe factors to the operators. The oil spill is now solved and the production environment is improved. 3) Realizing the discharge of oil in the sewage reaches | The environmental protection department of the standard factory regularly checks the oil content of the sewage to meet the discharge standard, which not only protects the natural environment, but also achieves certain social benefits. 4 Conclusion Although the leakage of lubricating oil in rolling mill equipment is long-term Old problems, as long as the reasons for careful analysis, take a practical and feasible sealing method - apply new sealing materials, improve the sealing structure, strengthen the management of lubrication and sealing, oil leakage problem can get better control of the exhaust fan impeller wear With the repair of Xia Weimin (Hubei Egang Sintering Plant and the method of adding lining and pile wear-resistant welding layer, the effect is good and the service life is greatly improved.
The 75m2 sintering machine of the Egang Group's sintering plant was completed and put into operation in 1993. The S7200 exhaust fan is an important supporting equipment for the 75m2 sintering machine, and the exhaust fan impeller is the core key component. The service life and safe operation of the impeller are directly related to the production cost and economic benefit of the branch. In 1997, the impeller of the exhaust fan was put into normal operation after being repaired by welding and surfacing. In 1998, the blade was seriously worn and repaired by the same method. After nearly one month of operation, it was found that some of the double-intake blades experienced some severe wear and caused the impeller to be unbalanced and the support tile and the thrust tile were all shattered. . At one time, the fan impeller bearing was seriously damaged in a short period of time, and the unplanned maintenance time increased linearly, which led to economic loss. Therefore, improving the efficiency of the sintering exhaust fan, reducing wear and prolonging the service life is a major issue for the technical transformation of the sintering exhaust fan.
1 Fan impeller wear state Although the fan impeller is repaired twice, it is still worn. The first repair is preheating repair welding, the welding rod is 212; the second repair is preheating repair welding, the welding rod is 322, the second repair The welding between the blade and the middle plate can only fill the groove with high wear. Because the blade working surface wears too much, the welding will generate excessive welding stress. When the impeller runs at high speed, the welding stress is released under the action of centrifugal force. The impeller wear state of the weld is changed. The blade and the middle plate weld area are seriously worn. The thinnest blade has a thickness of only about 4 mm, and the wear of each piece is uneven. The wear width of the blade face is about 20 mm. When the wear height on both sides of the middle plate is about 10mm and the high-speed operation is out of balance, the measurement vibration parameter is V vibration=10mm/s, the bearing temperature on both sides is 64, the impeller is seriously depleted. After inspection and measurement, the impeller is preliminarily determined as the scrapped component.
2 Impeller wear analysis The wear process of the impeller is more complicated from the microscopic analysis. A large number of data and equipment status shows that the wear of the exhaust fan impeller mainly comes from the following aspects.
2.1 Abrasive wear Abrasive wear is the micro-cutting of the metal surface when the hard particles are under pressure. The so-called abrasive is a solid abrasive composed of a large amount of iron powder, mineral powder, soot, etc. in the flue gas of the exhaust fan. Under the action of pressure, the stress caused by the relative movement of the surface of the impeller that is in contact with the impeller is contacted at a certain speed. Wear 2.2 Erosion Wear Erosion is the surface damage caused by the impact of solid dust and other hard particles on the solid surface. Also called “impact biteâ€, the impact wear is mainly manifested in the wear of the blade head, which is composed of hard particles in the airflow. Under the action of inertia and pressure, it directly impacts the blade head. If the suction dampers on both sides are not synchronized, the inertia and airflow pressure are not uniform, the impact wear on both sides of the blade is deviated, and the impeller impact wear causes the head to wear thin. Unbalanced and unbalanced.
2.3 Corrosion Corrosion Corrosion is a metal damage caused by chemical or electrochemical action. A corroded surface is a concentrated representation of many anodes and cathodes shorted through the parent metal. There are many factors that cause impeller corrosion, but mainly the chemical properties of the medium. The gas medium of the fan contains a large amount of active gas with certain corrosive action such as CO2CO2SO.N2HCI, and contains hard particles with certain particle size and strength such as Fe34Fe23SiOCaC3. These corrosive media and dust cause corrosion and wear on the working surface of the impeller. The corrosive action of the acidic medium HCISO2 and ftO to form H2SO3 is very strong, especially the SiO2 particles have the most serious wear on the impeller.
In addition, the wear of the impeller is also closely related to the peripheral speed of the impeller, the pressure of the gas medium, the particle size of the dust, the impact velocity and the impact angle, the parameters of the impeller working medium and the properties of the impeller material. In addition, the 600 multi-tube high-efficiency precipitator of the machine head has a long service life, the cyclone and the air duct are blocked, the dust removal efficiency is reduced, and the opening and closing angles of the fan air intake pipe are also the objective reasons for the increase of the blade wear.
3 Repair of worn impeller According to the existing impeller blade wear condition, spraying (surfacing) wear-resistant hard alloy on the blade surface is an effective method to improve the life of the impeller. At present, the methods of adding wear-resistant layers at home and abroad mainly include: the blade working face is deposited with a strip-shaped washboard-type wear-resistant layer; the blade wear surface is completely worn and wear-resistant layer; the impeller is heavily abraded with a lining plate; Re-grinding the wear-resisting layer; in the severely abraded area of ​​the impeller, the ceramic blade is now working on the blade working surface and the intermediate plate, the wear is serious, the abrasive area is too large, the blade strength is too low, the unsafe factor is too large, not like the previous two piles The wear layer is simply restored, and only the fourth method above can be used, the liner is added, and the wear layer is piled up. That is, the strength of the blade is ensured, and the impact on the original weld is slowed down. The geometry and welding position of the abrasive lining are first filled with the 502 electrode in the severely worn area of ​​the original blade. The lining plate is made of 16Mn material and 6mm thick on both sides to process the chamfer 60 to ensure penetration and welding. The lining plate is drilled with 0 10mm holes in each section. After the lining plate is curved, it is matched with the blades, and then the holes are filled to ensure that the linings are not separated from the blades after the welds around the lining are abraded.
The welding process uses preheating, crossover and a short distance to reduce the impeller welding deformation. The welding rod is a pile of 212 wear-resistant welding rod, first welding 502 welding rod, and then supplementing the wear-resistant layer, increasing the vertical welding part on both sides of the wear-resistant middle plate, newly adding the wear-resistant layer and engaging with the wear-resistant layer on the liner. Finally, the wear layer is repaired to ensure the height and width of the wear layer.
Impeller repairing construction is difficult, each process is strict, ensuring repair quality, removing impurities, balance accuracy, and conducting strict dynamic and static balance test tests. After the test meets the requirements for use, it is put into normal operation in September 1998. The vibration parameter measured on the day is V-vibration = 0.4mm/s. The vibration parameter indicates that after the repair, the effect leaf is used to achieve the best standard of wheel operation after one year of operation, and the impeller vibration parameter V is increased by the liner and the accumulated wear-resistant layer. The method is effective for the repair of the impeller with severe wear. After one year's operation record, it shows that the fan impeller has been repaired and reused after fully meeting the technical requirements of the equipment. The life of the impeller has been improved from two years to more than three years. Reduce the cost of equipment spare parts.
The economic benefit analysis has saved the production cost of more than 240,000 yuan for the sintering plant. The impeller repair effect has provided useful experience for the technical transformation, savings and efficiency of the equipment management of the sintering plant in the future.
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