What’s a rolling mill bearing?
Rolling mill bearings are used within the rolling trade, this is, rolling of non-ferrous metals, ferrous metals and non-metallic merchandise. It’s used for bearings on the roll diameter of the calender roll and at the drum. In most cases four-row cylindrical curler bearings are used to resist radial quite a bit, and thrust curler or thrust ball bearings and radial angular touch ball or radial curler bearings are used to resist axial quite a bit. At this time, oil and fuel lubrication or oil mist lubrication and grease are most commonly used for lubrication and cooling.
Influencing components and preventive measures of rolling mill bearings
1.1 Meeting high quality
(1) The lifetime of the bearing is inseparable from the design of the bearing seat. If the bearing seat is wrongly designed and manufactured, it’s going to motive asymmetric bearing drive and scale back the bearing existence. The bearing seat must be self-aligning to keep away from eccentric loading of the bearing because of the burning and deflection of the roll.
(2) Whether or not the dimensions, geometry, accuracy grade, and tolerance vary of spare portions associated with the bearing are in keeping with the design.
(3) Whether or not the smoothness and hardness of the touch floor matched with the bearing are throughout the specified vary, whether or not all clearances and interference suits meet the design necessities, and so on.
1.2 Set up of interior and outer jacket
1.2.1 Set up of interior sleeve
The interior sleeve and the roll neck of the four-row cylindrical curler bearing must be an interference are compatible. Throughout set up, the temperature must be heated to 80-90 °C, and the temperature must no longer exceed 100 °C. In a different way, the bearing ring raceway and rolling parts will likely be simply annealed, which is able to impact the hardness and resistance.
Abrasiveness, leading to lowered bearing existence and untimely failure. When the use of the heating option to set up the bearing, the bearing must be briefly got rid of from the oil after the oil temperature reaches the desired temperature for 10 mins, and put in at the shaft whilst it’s nonetheless sizzling. If vital, a little bit power will also be implemented to the tip face of the bearing interior ring with the set up instrument, which makes it more straightforward to put in.
After the bearing is put in at the shaft, the internal ring will have to be pressed straight away till it cools. It’s in most cases heated with induction warmers or oil, and the usage of torches is illegal. When the internal sleeve is put in at the roll neck, it’s in shut touch with the water holding ring to stop the water holding ring from shifting.
1.2.2 Set up of the jacket
The outer sleeve of the four-row cylindrical curler bearing is a transition are compatible with the internal hollow of the bearing seat. When assembling, evenly force the entire consisting of the jacket, rollers and cage into the bearing seat with a copper rod, and connect the tip quilt towards the internal facet.
When putting in the outer casing, be aware of the markings at the finish face and the tip face of the cage. It can’t be put in in opposite. It must be put in within the order of the preliminary state when the bearing is unpacked to stop the bearing from burning because of asymmetric drive at the rollers.
When putting in the bearing, the bearing must be positioned horizontally. After the bearing is put in, its drive vary must be marked for key inspection when the curler is changed.
1.3 Right kind meeting of bearing seals
Bearing seals will also be regarded as to make use of abnormal fluororubber skeleton seals, which aren’t simplest affordable, but in addition can reach excellent effects with cheap use. When the rolling mill is in a horizontal state, the lip of the shaft sealing ring within the static labyrinth on either side will have to be put in towards the outdoor of the bearing, which will successfully save you the splashing of cooling water and oxide scale; when the rolling mill is in a vertical state, the interior of the labyrinth at the transmission facet The lip of the sealing ring is put in in opposition to the interior of the bearing, which will successfully save you the overflow of lubricating oil because of the downward gravity; the lip of the sealing ring within the labyrinth at the non-transmission facet could also be put in in opposition to the outdoor of the bearing, which will successfully save you the splashing of cooling water.
1.4 Cheap collection of bearing grease
For the reason that usually used grease for bearings is abnormal 3#MoS2 lithium-based grease, it has the disadvantages of excessive viscosity, low penetration, excessive temperature resistance and excessive pace resistance.
Additionally, it’s simple to motive atypical put on and burn out of the bearing because of the hardening of the grease and the failure to lubricate the bearing in most cases. In view of those disadvantages that aren’t conducive to the usage of bearings, it’s endorsed to make use of excessive power lithium complicated grease in attention of the above components.
1.5 Inspection of bearings
1.5.1 Inspection of bearings all the way through operation
In step with the necessities of the bearing use setting, the bearing must be incessantly listened to, seen and measured. Listening is to make use of the desired device to stand the radial housing of the bearing axial finish quilt and bearing seat, and concentrate intently to the opposite finish to look if there may be any have an effect on sound and mechanical friction sound all the way through the operation of the bearing; commentary is to look at the running setting, set up place, vibration deviation Take a look at whether or not there’s a dangerous setting; the size is to make use of a thermometer and a vibration meter to quantitatively stumble on the bearing seat.
During the above strategies, it may be made up our minds whether or not the bearing is in a typical state all the way through operation and the measures to be taken, the faults and preventive measures that the bearing is liable to happen all the way through operation.
1.5.2 Inspection of bearings at relaxation
Take a look at the tightening of the related spare portions, whether or not the portions are in the right kind place, whether or not there may be looseness, and so on. All the time take a look at the bearing seat for tightness and looseness.
Particularly, there will have to be no axial clearance between the operation facet bearing seat and the rolling stand, and the matching hole between the transmission facet bearing seat and the rolling stand window will have to be lowered up to imaginable, in an effort to scale back the have an effect on of the force shaft runout at the bearing.
As well as, the bearing lubricant will also be examined to test whether or not the lubricating oil enters the sundries, iron oxide scale, water, and so on. Roughing turbines are in most cases subjected to robust surprise quite a bit, the bearings vibrate very much, and the grease is definitely misplaced. Due to this fact, the grease is needed to have robust adhesion, which will firmly adhere to the outside of the portions, a part of which lubricates the bearing at the raceway, and the remainder is saved within the interior area of the bearing for sealing.
If exterior dust penetrates into the bearing seat, the primary contamination is the grease close to the outer facet, which reasons the outside of the bearing portions to put on. With the rise of dust, the wear and tear floor will build up, and on the identical time, the cracks within the sign layer will steadily extend, and in any case the ferrule will likely be cracked.
1.5.3 Inspection after dismantling of bearings
Because of the huge rolling capability of the one groove of the roughing mill, the roll converting cycle is lengthy. After the roll is changed, the cleansing agent can be utilized to wash the bearing, dry it with compressed air, after which investigate cross-check the curler, cage and rolling. The rollers and raceways have dents, pitting and different phenomena, which must get replaced in line with the precise stipulations. On the identical time, take a look at the radial clearance of the axial sealing field. After the take a look at is proper, upload lubricant for backup.
Rolling mill bearing classification
(1) Round curler bearings
The configuration of rolling mill bearings at the rolling mill is other. At the moment, two units of round curler bearings have been principally put in at the identical roll neck in parallel. This configuration principally met the manufacturing stipulations at the moment, and the rolling pace may succeed in 600rpm.
Then again, as the rate will increase, its shortcomings turn out to be extra distinguished: brief bearing existence, excessive intake, low precision of completed merchandise, severe roll neck put on, huge axial motion of the roll, and so on.
(2) 4-row cylindrical curler bearing + thrust bearing
The interior diameter of the cylindrical curler bearing is tightly fitted with the roll neck and will resist radial drive. It has some great benefits of huge load capability, excessive prohibit pace, excessive precision, separable and interchangeable interior and outer rings, simple processing, low manufacturing price, and handy set up and disassembly.
The thrust bearing bears the axial drive, and the precise construction kind will also be decided on in line with the traits of the rolling mill.
When the burden is heavy and the rate is low, it’s supplied with a thrust curler bearing to undergo the thrust load with a small axial clearance. When the rolling pace is excessive, with angular touch ball bearing, no longer simplest the prohibit pace is excessive, but in addition the axial clearance will also be strictly managed all the way through operation.
The rolls will also be tightly guided within the axial path and will undergo the overall axial load drive. This kind of bearing configuration no longer simplest has lengthy bearing existence, excessive reliability, but in addition has many benefits corresponding to excessive precision and simple keep an eye on of rolling merchandise, so it’s the most generally used, most commonly utilized in cord rod rolling turbines, sheet rolling turbines, foil rolling turbines, and double reinforce rolling turbines. Again-up rolls for chilly rolling turbines and sizzling rolling turbines, and so on.
(3) 4-row tapered curler bearings
Tapered curler bearings can undergo each radial drive and axial drive, and no thrust bearing is needed, so the principle engine is extra compact. The interior diameter of the tapered curler bearing adopts a unfastened are compatible with the roll neck, which may be very handy for set up and disassembly, however from time to time sliding creep could also be brought about because of the unfastened are compatible, so the internal diameter is ceaselessly machined with a spiral oil groove.
This configuration kind continues to be broadly used, such because the paintings rolls of four-high sizzling rolling turbines and chilly rolling turbines, billet turbines, metal beam rolling turbines and different events.
4-row cylindrical curler bearings and six-row cylindrical curler bearings are nearly solely utilized in roll necks, drums and rolling turbines of rolling stands. Those bearings have low friction in comparison to different curler bearings. Since those bearings are in most cases fixed at the roll neck with an interference are compatible, they’re particularly appropriate for rolling mill programs with excessive rolling speeds.
The low cross-section of those bearings lets in the usage of quite huge roll neck diameters in comparison to roll diameters. The radial load capability may be very excessive because of the huge selection of rollers that may be accommodated.
Multi-row cylindrical curler bearings can simplest resist radial quite a bit. Due to this fact, those bearings are fixed with deep groove ball bearings or angular touch ball bearings, or tapered curler bearings of radial design or thrust design, which can be subjected to axial quite a bit. 4-row and six-row tapered curler bearings are of cut up design, this is, the bearing ring with integral flange and the curler and cage meeting will also be put in one by one from the cut up bearing ring, or all bearing parts will also be put in one by one.
This significantly simplifies bearing set up, repairs and inspection. The bearing can undergo a definite prohibit of axial displacement of the shaft relative to the bearing seat. 4-row cylindrical curler bearings have a cylindrical bore, and a few sizes also are to be had with a tapered bore. Bearings with tapered bores will also be adjusted all the way through set up to acquire a definite radial inner clearance or a definite preload.
Rolling mill bearing procedure
The design of rolling mill bearings, the burning lack of rolling mill bearings is said to many components, which is most often standard. The burning lack of conventional angular touch bearings of aluminum foil rolling turbines is a global drawback. I in my view suppose that lubrication is essential. The impact of oil mist lubrication Somewhat higher, there could also be the problem of bearing set up clearance.
As well as, there are lots of components corresponding to the space between the shaft finish baffle and the bearing seat, and the burden trade of the bearing outer ring brought about by means of the bending cylinder. . There also are bearing outer ring spring buffers and so forth.
- 4-row cylindrical small curler bearings are most often used for the backup roll, and the internal ring is statically matched with the curler. Normally, after the taper sleeve is put in, the internal ring is put in, and the outer circle of the curler is finely floor according to the internal ring. The axial drive generated all the way through the rolling procedure must be supported by means of bearings. Normally, back-to-back double-row angular touch ball bearings, face-to-face double-row tapered curler bearings, thrust bearings and four-point angular touch ball bearings are used. , The home producers of the tile shaft merchandise are higher, and the overseas producers of the American iron mom are higher.
- 4-row tapered curler bearings are most often used for paintings roll bearings. As a result of their construction, the internal ring is in dynamic are compatible with the roll, this is to mention, when the roll is regrind, the bearing is got rid of in conjunction with the bearing seat, which itself can undergo a specific amount of shaft. Due to this fact, the axial drive of a few small rolling turbines is borne on its own, whilst some greater or upper precision rolling turbines most often use axial drive bearings.