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 a lot, and thrust curler or thrust ball bearings and radial angular touch ball or radial curler bearings are used to resist axial a lot. At the moment, oil and gasoline 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’ll reason asymmetric bearing power and scale back the bearing lifestyles. 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 scale, 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 so forth.
1.2 Set up of inside and outer jacket
1.2.1 Set up of inside sleeve
The internal sleeve and the roll neck of the four-row cylindrical curler bearing must be an interference have compatibility. Right 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 parts might be simply annealed, which is able to have an effect on the hardness and resistance.
Abrasiveness, leading to decreased bearing lifestyles and untimely failure. When the use of the heating way to set up the bearing, the bearing must be temporarily 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 essential, somewhat power can also be implemented to the top face of the bearing inside 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 should be pressed right away till it cools. It’s typically heated with induction warmers or oil, and the usage of torches is unlawful. When the interior sleeve is put in at the roll neck, it’s in shut touch with the water protecting ring to stop the water protecting 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, flippantly power the entire consisting of the jacket, rollers and cage into the bearing seat with a copper rod, and attach the top quilt in opposition to the interior facet.
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 stop the bearing from burning because of asymmetric power at the rollers.
When putting in the bearing, the bearing must be positioned horizontally. After the bearing is put in, its power vary must be marked for key inspection when the curler is changed.
1.3 Right kind meeting of bearing seals
Bearing seals can also be thought to be to make use of abnormal fluororubber skeleton seals, which don’t seem to be simplest reasonable, but additionally can succeed in excellent effects with affordable use. When the rolling mill is in a horizontal state, the lip of the shaft sealing ring within the static labyrinth on each side should be put in towards the out of doors 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 in opposition to 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 may be put in in opposition to the out of doors of the bearing, which is able to successfully save you the splashing of cooling water.
1.4 Cheap number of bearing grease
Because the recurrently 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 reason unusual 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 the usage of bearings, it is strongly recommended to make use of excessive power lithium advanced grease in attention of the above components.
1.5 Inspection of bearings
1.5.1 Inspection of bearings all over operation
Consistent with the necessities of the bearing use atmosphere, the bearing must be frequently listened to, seen and measured. Listening is to make use of the required device to stand the radial housing of the bearing axial finish quilt and bearing seat, and pay attention carefully to the opposite finish to peer if there may be any affect sound and mechanical friction sound all over the operation of the bearing; commentary 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.
Throughout the above strategies, it may be decided whether or not the bearing is in a regular state all over operation and the measures to be taken, the faults and preventive measures that the bearing is vulnerable to happen all over operation.
1.5.2 Inspection of bearings at relaxation
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 so forth. 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 decreased up to imaginable, so that you can scale back the affect of the power shaft runout at the bearing.
As well as, the bearing lubricant can also be examined to test whether or not the lubricating oil enters the sundries, iron oxide scale, water, and so forth. Roughing generators are typically subjected to sturdy surprise a lot, the bearings vibrate very much, and the grease is definitely misplaced. Due to this fact, the grease is needed to have sturdy adhesion, which is able to 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 inside area 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 outside of the bearing portions to put on. With the rise of filth, the damage floor will building up, and on the similar time, the cracks within the sign layer will step by step amplify, and in spite of everything the ferrule might 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 scrub 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 step 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 have 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 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, massive axial motion of the roll, and so forth.
(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 power. It has some great benefits of massive load capability, excessive prohibit velocity, excessive precision, separable and interchangeable inside and outer rings, simple processing, low manufacturing value, and handy set up and disassembly.
The thrust bearing bears the axial power, and the precise construction kind can also be decided on in step with the traits of the rolling mill.
When the burden is heavy and the velocity is low, it’s provided 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 simplest the prohibit velocity is excessive, but additionally the axial clearance can also be strictly managed all over operation.
The rolls can also be tightly guided within the axial path and will undergo the overall axial load power. This sort of bearing configuration now not simplest has lengthy bearing lifestyles, excessive reliability, but additionally has many benefits corresponding to excessive precision and simple regulate of rolling merchandise, so it’s the most generally used, most commonly utilized in cord rod rolling generators, sheet rolling generators, foil rolling generators, and double give a boost to rolling generators. Again-up rolls for chilly rolling generators and scorching rolling generators, and so forth.
(3) 4-row tapered curler bearings
Tapered curler bearings can undergo each radial power and axial power, 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 could be very handy for set up and disassembly, however on occasion sliding creep could also be led to because of the free have compatibility, so the interior diameter is regularly machined with a spiral oil groove.
This configuration kind continues to be extensively used, such because the paintings rolls of four-high scorching rolling generators and chilly rolling generators, billet generators, metal beam rolling generators and different events.
4-row cylindrical curler bearings and six-row cylindrical curler bearings are nearly solely utilized in roll necks, drums and rolling generators of rolling stands. Those bearings have low friction in comparison to different curler bearings. Since those bearings are typically fixed at the roll neck with an interference have compatibility, they’re particularly appropriate for rolling mill programs with excessive rolling speeds.
The low cross-section of those bearings permits the usage of somewhat massive roll neck diameters in comparison to roll diameters. The radial load capability could be very excessive because of the huge collection of rollers that may be accommodated.
Multi-row cylindrical curler bearings can simplest resist radial a lot. 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, that are subjected to axial a lot. 4-row and six-row tapered curler bearings are of break up design, this is, the bearing ring with integral flange and the curler and cage meeting can also be put in one by one from the break up bearing ring, or all bearing parts can 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 can also be adjusted all over 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 expounded to many components, which is usually customary. The burning lack of conventional angular touch bearings of aluminum foil rolling generators is a world downside. I individually suppose that lubrication is essential. The impact of oil mist lubrication Moderately higher, there may 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 exchange of the bearing outer ring led to by means of 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. 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 according to the interior ring. The axial power generated all over the rolling procedure must be supported by means of 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 usually used for paintings roll bearings. As a result 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 power of a few small rolling generators is borne on its own, whilst some greater or upper precision rolling generators usually use axial power bearings.