Keyword：Wide and heavy plate rolling, work roll bearings, work rolls
In order to improve the service life of the work roll bearings of the extra heavy plate mill, a steel mill analyzed the working conditions of the work roll bearings and the current bearing maintenance methods to obtain the main reasons affecting the service life of the work roll bearings of the rolling mill. By formulating reasonable bearing maintenance methods and quick bearing cleaning equipment, the service life of work roll bearings in extra-heavy plate mills has been significantly improved.
The results show that reasonable bearing maintenance methods and quick bearing cleaning equipment can reduce manpower, improve cleaning effect, increase the service life of work roll bearings, reduce the cost of spare parts, and improve the work efficiency of work rolls.
The 4300 mm wide and thick plate production line of a factory is a key project for the factory to form a complete set of iron, steel and material production and realize a complete process flow. After it is completed and put into operation, the annual output of wide and thick plates will be 1.2 million tons. Through transformation and upgrading, it will eventually reach a production scale of 1.2 million to 2 million tons. The rolling process is as follows: After the billet is descaled by high-pressure water, it is sent to the four rough rolling mills by the track for widening and thickness rolling. When the width reaches the requirement, it is sent to the four finishing mills by the transport roller table. Four finishing mills carry out finishing rolling until the thickness requirements are met. After rolling, the steel plate is straightened and sent to the finishing line for fixed-length and fixed-width shearing.
Among them, the bearings of the work rolls of the rolling mill must meet high requirements for use. In the daily production process of the rolling mill production line, the bearings of the work rolls are often burned out. Certain economic costs and increased costs. Therefore, in addition to the application of good brand bearings, the necessary regular maintenance and inspection of the bearings should be carried out, which has delayed the service life of the bearings and reduced the cost of bearing spare parts, which is beneficial to reducing unnecessary downtime.
Existing problems
During the rolling process of the rolling mill, a large radial force will be generated, and at the same time, the high-speed rotation of the work roll will cause fatigue pitting and even gluing of the bearing. At the same time, the work roll bearings of the rolling mill have large dimensions and a large installed capacity online, and each bearing has to be cleaned off-line for one week of online work to remove waste grease and check the dimensions of the inner ring, outer ring, and rolling elements of the bearing. Therefore, the effect of cleaning the work roll bearing of the rolling mill directly affects the inspection of the bearing. And at present most iron and steel enterprises, clean rolling mill work roll bearing and all are to rely on artificially, utilize dishcloth, brush to clean rolling mill work roll bearing. Disadvantages are heavy oil pollution, hard work to rotate the bearing during cleaning, and poor cleaning effect, which not only wastes labor investment and maintenance funds, but also often results in inadequate bearing inspection due to dirty bearing cleaning, resulting in failure of the rolling mill. Waste of precious production time also affects enterprise output and economic benefits.
Improvement measures
Reasonable and regular bearing maintenance method
One of the reasons for bearing failure is that the bearing lacks regular and reasonable maintenance, which accelerates the damage of the bearing. For this reason, a reasonable and regular bearing maintenance method is formulated according to the production situation of the rolling mill.
(1) Number each bearing and establish a bearing life file;
(2) Regularly disassemble and clean the bearings, check the dimensional accuracy of the mating surface of the bearing seat and the roller, and repair the out-of-tolerance rollers. make detailed records;
(3) During the high-speed working process of the work roll, the outer ring of the bearing and the bearing cage will produce certain vibrations. If the bearing works under this vibration for a long time, fatigue peeling of the outer ring roller table will occur, and serious failure of the bearing will occur. Therefore, the bearings at both ends of the work roll can be replaced regularly to reduce the fatigue spalling of the bearings under the action of a single rolling force.
Reasonable and efficient cleaning of bearing equipment
In order to solve the problems of time-consuming and labor-intensive manual cleaning of work roll bearings of rolling mills, poor cleaning effect, and influence on bearing inspection, a self-made quick cleaning equipment for work roll bearings of rolling mills was developed. Figure 1 shows the quick cleaning equipment for rolling mill work roll bearings.
The equipment mainly includes motor 1, reducer; 2, lower handle shaft; 3, upper cover; 4, upper cover hinge; 5, fuel tank hinge; 6, bearing outer diameter fixing screw; 7, lower connecting hand shaft fixing nut; 8. Fuel tank; 9. Oil drain valve; 10. Traveling wheel; 11. Inner spacer; 12. Bearing; 13. Lower positioning groove; 14. Upper positioning groove; 15. Bearing drive plate; 16. Lower handle; 17 , rubber receiver; 18, upper receiver; 19, handle; 20, resting hand.
The steps of using the quick cleaning equipment for the above rolling mill work roll bearings are as follows :
(1) Butt and fix the inner diameter of the bearing 13 with the buckle of the inner spacer 12;
(2) Fill the fuel tank with proper cleaning fluid;
(3) Fasten the bearing drive plate 16 equipped with the lower handle shaft 3, the lower handle shaft fixing nut 8, the lower handle 17, and the rubber receiver 18 on the outer diameter of the bearing 13 through the bearing outer diameter fixing screw 7;
(4) Close the upper cover 4 so that the upper handle 19 cooperates with the rubber handle 18 and the lower receiving teeth;
(5) Fix the lower positioning slot 14 and the upper positioning slot 15 with bolts;
(6) Turn on the power supply, rotate the bearing until the bearing is cleaned; the advantages of the quick cleaning equipment for the work roll bearing of the rolling mill are: simple structure, low manufacturing cost, easy maintenance, and the overall equipment is easy to disassemble and carry; the inner diameter of the bearing is fixed, and the outer Radial rotation makes the bearing rollers rotate, and the lubricating oil on the bearing rollers is fully in contact with the cleaning liquid, which is clean and efficient.
Conclusion:
(1) By formulating a reasonable bearing maintenance method, establishing bearing files, formulating standard maintenance and cleaning methods, and regularly replacing the bearings at both ends of the work roll, bearing failure can be greatly reduced and the service life of the bearing can be improved.
(2) According to the actual working conditions of cleaning work roll bearings, design and manufacture bearing quick cleaning equipment, which can clean bearings cleanly and efficiently, and at the same time reduce the consumption of cleaning fluid.
(3) After more than one year of application, the maintenance cost of spare parts for rolling mill work roll bearings has been reduced by 25% compared with the previous year, and the failure rate has been reduced by 24% compared with the previous year. To sum up, by formulating reasonable bearing maintenance methods and quick bearing cleaning equipment, the maintenance cost is reduced and the stable operation of the working rolls of the rolling mill is guaranteed. It has good social and economic benefits. It can be used as a reference for the maintenance of work roll bearings of other rolling mills.
