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. Generally four-row cylindrical curler bearings are used to resist radial lots, and thrust curler or thrust ball bearings and radial angular touch ball or radial curler bearings are used to resist axial lots. At the present, 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 purpose asymmetric bearing drive and scale 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 scale, 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 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 have compatibility. 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 shall be simply annealed, which can have an effect on the hardness and resistance.
Abrasiveness, leading to diminished bearing lifestyles and untimely failure. When the use 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 desired temperature for 10 mins, and put in at the shaft whilst it’s nonetheless sizzling. If essential, slightly force may also be carried out to the top face of the bearing internal ring with the set up instrument, which makes it more uncomplicated to put in.
After the bearing is put in at the shaft, the interior ring should be pressed straight away 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 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 have compatibility with the interior hollow of the bearing seat. When assembling, calmly force the entire consisting of the jacket, rollers and cage into the bearing seat with a copper rod, and fasten the top quilt towards the interior facet.
When putting in the outer casing, be aware 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 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 Correct meeting of bearing seals
Bearing seals may also be thought to be to make use of abnormal fluororubber skeleton seals, which don’t seem to be most effective reasonable, but additionally 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 should be put in towards the outdoor of the bearing, which is able to 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 against the interior of the bearing, which is able to 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 against the outdoor of the bearing, which is able to successfully save you the splashing of cooling water.
1.4 Affordable number 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 velocity resistance.
Additionally, it’s simple to purpose strange put on and burn out of the bearing because of the hardening of the grease and the failure to lubricate the bearing typically. In view of those disadvantages that don’t seem to be conducive to using bearings, it is suggested to make use of excessive force lithium advanced grease in attention of the above components.
1.5 Inspection of bearings
1.5.1 Inspection of bearings right through operation
In keeping with the necessities of the bearing use atmosphere, the bearing must be ceaselessly listened to, noticed 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 pay attention carefully to the opposite finish to look if there’s any have an effect on sound and mechanical friction sound right through the operation of the bearing; statement is to look at the running atmosphere, set up place, vibration deviation Take a look at whether or not there’s a unhealthy atmosphere; the size is to make use of a thermometer and a vibration meter to quantitatively hit upon the bearing seat.
During the above strategies, it may be made up our minds whether or not the bearing is in a typical state right through operation and the measures to be taken, the faults and preventive measures that the bearing is at risk of happen right through operation.
1.5.2 Inspection of bearings at leisure
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’s looseness, and so on. All the time test the bearing seat for tightness and looseness.
Particularly, there should 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 should be diminished up to conceivable, so to scale back the have an effect on of the force 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 so on. Roughing turbines are most often subjected to robust surprise lots, the bearings vibrate a great deal, and the grease is definitely misplaced. Due to this fact, the grease is needed to have robust adhesion, which is able to firmly adhere to the skin of the portions, a part of which lubricates the bearing at the raceway, and the remainder is stored within the internal house of the bearing for sealing.
If exterior filth penetrates into the bearing seat, the primary contamination is the grease close to the outer facet, which reasons the skin of the bearing portions to put on. With the rise of filth, the wear and tear floor will building up, and on the similar time, the cracks within the sign layer will progressively increase, and after all the ferrule shall 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 keeping with the precise stipulations. On the similar 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 had been basically put in at the similar roll neck in parallel. This configuration mainly met the manufacturing stipulations at the moment, and the rolling velocity may just achieve 600rpm.
Then again, as the rate will increase, its shortcomings transform extra outstanding: quick bearing lifestyles, excessive intake, low precision of completed merchandise, severe roll neck put on, massive axial motion of the roll, and so on.
(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 drive. It has some great benefits of massive load capability, excessive prohibit velocity, 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 drive, and the precise construction kind may also be decided on in keeping with the traits of the rolling mill.
When the weight 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 velocity is excessive, with angular touch ball bearing, now not most effective the prohibit velocity 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 path and will undergo the overall axial load drive. This sort of bearing configuration now not most effective has lengthy bearing lifestyles, excessive reliability, but additionally has many benefits equivalent to excessive precision and simple keep watch over 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 fortify 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 internal diameter of the tapered curler bearing adopts a free have compatibility with the roll neck, which may be very handy for set up and disassembly, however infrequently sliding creep could also be brought about because of the free have compatibility, so the interior diameter is continuously 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 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 have compatibility, they’re particularly appropriate for rolling mill packages with excessive rolling speeds.
The low cross-section of those bearings lets in using slightly massive roll neck diameters in comparison to roll diameters. The radial load capability may be very excessive because of the huge choice of rollers that may be accommodated.
Multi-row cylindrical curler bearings can most effective resist radial lots. 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 lots. 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 parts may also be put in one at a time.
This significantly simplifies bearing set up, repairs and inspection. The bearing can undergo a undeniable 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 may also be adjusted right through set up to acquire a undeniable radial interior clearance or a undeniable 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 normally customary. The burning lack of conventional angular touch bearings of aluminum foil rolling turbines is a world downside. I for my part assume 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 equivalent to the space between the shaft finish baffle and the bearing seat, and the weight exchange of the bearing outer ring brought about via the bending cylinder. . There also are bearing outer ring spring buffers and so forth.
- 4-row cylindrical small curler bearings are normally used for the backup roll, and the interior ring is statically matched with the curler. In most cases, after the taper sleeve is put in, the interior ring is put in, and the outer circle of the curler is finely floor in keeping with the interior ring. The axial drive generated right through the rolling procedure must be supported via bearings. In most cases, 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 normally used for paintings roll bearings. On account of their construction, the interior ring is in dynamic have compatibility with the roll, this is to mention, when the roll is regrind, the bearing is got rid of at the side of the bearing seat, which itself can undergo a certain quantity 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 normally use axial drive bearings.