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. Most often 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 the moment, oil and gasoline lubrication or oil mist lubrication and grease are most commonly used for lubrication and cooling.
Influencing elements 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 badly designed and manufactured, it is going to motive asymmetric bearing pressure and cut back the bearing lifestyles. The bearing seat must be self-aligning to steer clear of 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 step 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 many others.
1.2 Set up of internal and outer jacket
1.2.1 Set up of internal sleeve
The internal sleeve and the roll neck of the four-row cylindrical curler bearing must be an interference are compatible. All through set up, the temperature must be heated to 80-90 °C, and the temperature must now not exceed 100 °C. In a different way, the bearing ring raceway and rolling components might be simply annealed, which is able to have an effect on the hardness and resistance.
Abrasiveness, leading to diminished bearing lifestyles and untimely failure. When the usage of the heating approach to set up the bearing, the bearing must be briefly got rid of from the oil after the oil temperature reaches the required temperature for 10 mins, and put in at the shaft whilst it’s nonetheless scorching. If important, a bit drive may also be carried out to the top face of the bearing internal ring with the set up device, which makes it more straightforward to put in.
After the bearing is put in at the shaft, the interior ring will have to be pressed instantly till it cools. It’s most often heated with induction warmers or oil, and using torches is against the law. When the interior sleeve is put in at the roll neck, it’s in shut touch with the water maintaining ring to forestall the water maintaining ring from transferring.
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 interior hollow of the bearing seat. When assembling, flippantly pressure the entire consisting of the jacket, rollers and cage into the bearing seat with a copper rod, and attach the top duvet towards the interior aspect.
When putting in the outer casing, take note of the markings at the finish face and the top 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 forestall the bearing from burning because of asymmetric pressure at the rollers.
When putting in the bearing, the bearing must be positioned horizontally. After the bearing is put in, its pressure vary must be marked for key inspection when the curler is changed.
1.3 Right kind meeting of bearing seals
Bearing seals may also be regarded as to make use of atypical fluororubber skeleton seals, which aren’t most effective reasonable, but additionally can succeed in just right 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 all sides 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 aspect The lip of the sealing ring is put in against 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 aspect may be put in against the outdoor of the bearing, which will successfully save you the splashing of cooling water.
1.4 Affordable choice of bearing grease
Because the often used grease for bearings is atypical 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 strange put on and burn out of the bearing because of the hardening of the grease and the failure to lubricate the bearing generally. In view of those disadvantages that aren’t conducive to using bearings, it is suggested to make use of excessive drive lithium complicated grease in attention of the above elements.
1.5 Inspection of bearings
1.5.1 Inspection of bearings right through operation
Consistent with the necessities of the bearing use atmosphere, the bearing must be incessantly listened to, noticed and measured. Listening is to make use of the required software to stand the radial housing of the bearing axial finish duvet and bearing seat, and concentrate carefully to the opposite finish to peer if there may be any affect sound and mechanical friction sound right through the operation of the bearing; statement is to look at the working atmosphere, set up place, vibration deviation Test whether or not there’s a dangerous atmosphere; the dimension is to make use of a thermometer and a vibration meter to quantitatively discover the bearing seat.
During the above strategies, it may be made up our minds whether or not the bearing is in a standard state right through operation and the measures to be taken, the faults and preventive measures that the bearing is vulnerable to happen right through operation.
1.5.2 Inspection of bearings at leisure
Test 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 many others. All the time test the bearing seat for tightness and looseness.
Particularly, there will have to be no axial clearance between the operation aspect bearing seat and the rolling stand, and the matching hole between the transmission aspect bearing seat and the rolling stand window will have to be diminished up to imaginable, so that you can cut back the affect of the pressure shaft runout at the bearing.
As well as, the bearing lubricant may also be examined to test whether or not the lubricating oil enters the sundries, iron oxide scale, water, and many others. Roughing turbines are most often subjected to robust surprise quite a bit, the bearings vibrate a great deal, and the grease is definitely misplaced. Subsequently, 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 stored within the internal area of the bearing for sealing.
If exterior dust penetrates into the bearing seat, the primary contamination is the grease close to the outer aspect, which reasons the outside of the bearing portions to put on. With the rise of dust, the wear and tear floor will building up, and on the identical time, the cracks within the sign layer will progressively amplify, and in spite of everything the ferrule might be cracked.
1.5.3 Inspection after dismantling of bearings
Because of the massive rolling capability of the only groove of the roughing mill, the roll converting cycle is lengthy. After the roll is changed, the cleansing agent can be utilized to scrub the bearing, dry it with compressed air, after which check up on the curler, cage and rolling. The rollers and raceways have dents, pitting and different phenomena, which must get replaced in step with the precise prerequisites. On the identical time, test the radial clearance of the axial sealing field. After the test 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 prerequisites at the moment, and the rolling pace may achieve 600rpm.
On the other hand, as the velocity will increase, its shortcomings grow to be extra outstanding: quick bearing lifestyles, excessive intake, low precision of completed merchandise, critical roll neck put on, huge axial motion of the roll, and many others.
(2) 4-row cylindrical curler bearing + thrust bearing
The internal diameter of the cylindrical curler bearing is tightly fitted with the roll neck and will resist radial pressure. It has the benefits of huge load capability, excessive restrict pace, excessive precision, separable and interchangeable internal and outer rings, simple processing, low manufacturing value, and handy set up and disassembly.
The thrust bearing bears the axial pressure, and the precise construction kind may also be decided on in step with the traits of the rolling mill.
When the weight is heavy and the velocity 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, now not most effective the restrict pace is excessive, but additionally the axial clearance may also be strictly managed right through operation.
The rolls may also be tightly guided within the axial route and will undergo the overall axial load pressure. This kind of bearing configuration now not most effective has lengthy bearing lifestyles, excessive reliability, but additionally 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 twine rod rolling turbines, sheet rolling turbines, foil rolling turbines, and double improve rolling turbines. Again-up rolls for chilly rolling turbines and scorching rolling turbines, and many others.
(3) 4-row tapered curler bearings
Tapered curler bearings can undergo each radial pressure and axial pressure, and no thrust bearing is needed, so the primary engine is extra compact. The internal 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 every so often sliding creep could also be led to because of the unfastened are compatible, so the interior diameter is steadily machined with a spiral oil groove.
This configuration kind remains to be extensively used, such because the paintings rolls of four-high scorching 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 virtually completely 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 most often fixed at the roll neck with an interference are compatible, they’re particularly appropriate for rolling mill packages with excessive rolling speeds.
The low cross-section of those bearings permits using moderately huge roll neck diameters in comparison to roll diameters. The radial load capability may be very excessive because of the massive selection of rollers that may be accommodated.
Multi-row cylindrical curler bearings can most effective resist radial quite a bit. Subsequently, 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 might 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 may also be put in one at a time from the cut up bearing ring, or all bearing elements may also be put in one at a time.
This significantly simplifies bearing set up, repairs and inspection. The bearing can undergo a definite restrict 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 may also be adjusted right through set up to acquire a definite radial inside clearance or a definite preload.
Rolling mill bearing procedure
The design of rolling mill bearings, the burning lack of rolling mill bearings is expounded to many elements, which is usually commonplace. The burning lack of conventional angular touch bearings of aluminum foil rolling turbines is a global downside. I in my view assume that lubrication is essential. The impact of oil mist lubrication Somewhat higher, there may be the problem of bearing set up clearance.
As well as, there are lots of elements corresponding to the space between the shaft finish baffle and the bearing seat, and the weight exchange of the bearing outer ring led to through the bending cylinder. . There also are bearing outer ring spring buffers and so forth.
- 4-row cylindrical small curler bearings are usually used for the backup roll, and the interior ring is statically matched with the curler. Normally, after the taper sleeve is put in, the interior ring is put in, and the outer circle of the curler is finely floor in accordance with the interior ring. The axial pressure generated right through the rolling procedure must be supported through 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 international producers of the American iron mom are higher.
- 4-row tapered curler bearings are usually used for paintings roll bearings. As a result of their construction, the interior ring is in dynamic are compatible with the roll, this is to mention, when the roll is regrind, the bearing is got rid of along with the bearing seat, which itself can undergo a specific amount of shaft. Subsequently, the axial pressure of a few small rolling turbines is borne on its own, whilst some greater or upper precision rolling turbines usually use axial pressure bearings.