Cement mill back to powder screw conveyor six spiral leaf body between the use of hanging bearings fixed, due to the failure of hanging bearings caused by the cement mill shutdown. The use of the joint bearing instead of the hanging bearing, and the corresponding improvement of the hanger, the joint bearing and the hanging shaft interference assembly, the use of spherical plain bearings to replace the friction between the copper tile and the hanging shaft.
A cement grinding station cement mill back to the powder conveying equipment due to the process conditions, the LS series screw conveyor, because of the length of nearly 18m, six spiral leaves between the entities using hanging bearings fixed, a total of 5 hanging bearings. The original spiral equipment with hanging bearing is brass tile, hanging bearing frame, hanging shaft, hanging bearing frame nylon seal cover, oil cup and joint bolts. After running for a period of time, the cement mill, due to the failure of the roller bearing of the screw conveying equipment, caused the cement mill to stop, which seriously affected the running rate of the cement mill, and often failed to overhaul during the season of cement sales.
1 cause Analysis
1) The cement mill material mostly in 100 ℃, occasionally will appear 120 ℃ above; the cement mill lubrication part is now using the lithium-based grease because of the long-term high temperature easily loses the lubricating ability;
2) The cement mill material is fine granular powdery material, easy to enter the hanging bearing movement pair through the nylon seal cover clearance, causes the copper tile and the hanging axle relative movement carries on the dry friction;
3) Spiral conveyor equipment spiral vane long, hanging bearing in operation will appear in the rotation center and the theoretical axis shift;
4) The installation of the hanging bearing is at room temperature, and normal boot work is hot state, the temperature difference, the work of the spiral blade according to the metal expansion coefficient will be longer, so that the hanging bearing will be displaced or spiral leaf deformation arch.
If used in the past to replace the copper tile and hanging shaft of conventional repair methods, not only will affect the operating rate of equipment, while increasing the labor intensity of a large number of maintenance workers, increase maintenance costs. Therefore, we choose to use the joint bearing instead of hanging bearings, and the hanger has been improved accordingly.
1) The original design concept is brass and steel in the grease fully lubricated work when the friction coefficient is small, wear is mainly in the material soft copper tile, replace the copper tile than replace the lifting shaft much less work.
2) Instead of the friction between the copper tile and the hanging shaft, the joint bearing and the hanging shaft are used to assemble the interference, and the joint bearing can use its own rotary motion. The dry friction coefficient of steel and brass is 0.19, the dry friction coefficient of the joint bearing is 0.038, and the friction coefficient of steel and brass in the working state of lubricating grease is the same as that of the joint bearing. Because the bearing steel of the joint bearing is very high hardness, good abrasion resistance, the friction coefficient of the joint bearing is small and inlaid solid lubricant, does not need to fill grease lubrication, is the fineness small cement powder enters the joint bearing also does not cause the larger wear.
3) improved rear joint bearings no longer need to be sealed, the original oil cups and nylon sealing caps are no longer used.
4) The movable pin is designed on the hanger of the joint bearing, and the rotating center and axis can be freely corrected according to the wear of the joint bearing and the expansion and contraction of the spiral impeller.
5) Strengthen the connection reliability of the main drive shaft (head axle), the tail axis of the spiral vane to cancel the locating pin, so that the overall expansion of the spiral at the end of the tail axis digestion.
3 Transformation Effect
After the renovation of the monthly stop grinding overhaul open cover inspection, visual eye joint bearings did not find obvious wear, and then changed to about six months after the inspection, in the use of a year only obvious wear, until 18 months after the use of equipment for safe operation to give replacement. This transformation solves the cement mill because the return powder conveying equipment frequently stops replacing the copper tile, the equipment operation rate greatly increases, reduces the daily equipment maintenance labor intensity, reduces the inspection work lubrication workload, saves the maintenance cost 12000 yuan annually, saves 240kg lithium grease annually.
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