Reducing bearing temperatures through improved bushings

Abstract

A novel bushing (300) for use in bearings in rolling mills is disclosed. A feature of length Z is introduced on the inner portion (301) of the outer surface (303) of the bushing (300). This introduced feature allows the bushing (300) to deflect with a maximum radial deflection of δ mm as the load increases. This introduced feature addresses temperature increases inside the bushing (300) by allowing the bushing to deflect as the load increases.

Description

[Technical Field]

[0001] The present invention relates generally to the field of backup bearings for rolling mills, and more particularly to the field of oil film backup bearings, and more particularly to improving the temperature profile within the bearings during operation. [Background technology]

[0002] Figures 1(A) and 1(B) show a known oil film bearing assembly as described in U.S. Pat. No. 4,772,137. The industry standard is a cylindrical bushing (sometimes known as a bearing) and a sleeve (sometimes known as a journal) with a cylindrical outer diameter and a tapered inner diameter. The bushing has a cylindrical outer diameter that fits snugly within the chock (bearing housing), and the sleeve has an inward taper angle that closely matches the roll.

[0003] The '137 patent describes a typical rolling mill oil film bearing as follows: A roll 10 has a neck section 12, which may be conical, as shown in FIG. 1(A), or cylindrical in some alternative configurations. A sleeve 14 is received on and fixed relative to the neck section 12. The exterior of the sleeve defines a journal surface 16 of the roll neck. A bushing 18 has an inner bearing surface 20 that surrounds and rotatably supports the journal surface 16. The bushing is received by and fixed within a chock 22. The chock is closed at its outer end by an end plate 24 and a cover 26. A seal assembly 28 is provided between the roll and the inner end of the chock 22.

[0004] During normal operation of the rolling mill, when the rolls are rotating at a speed sufficient to operate under full hydrodynamic conditions, a continuous flow of oil is supplied through passages 29 in the chocks, supply ports 30 in the bushings, and one of a set of rebores 32 in the bearing surface 20. From here, oil enters between the bearing surface 20 and the rotating journal surface 16, forming a bearing load zone "Z" and a hydrodynamic length "L" H This fluid dynamic length "L" of the bushing forms a slightly wedge-shaped oil film 34 that is hydrodynamically maintained. H " is the length at which the bushing interacts with the sleeve and supports the oil film. In Figure 1(A), a load is applied through the roll at "SF". This load is reacted at the chock by force "F". This load zone is located on the same side as reaction force "F". The pressure profile at the load zone is shown schematically at "P" in Figure 1(A).

[0005] Conventional hydrostatic means are used to create the necessary oil film between the journal and bearing surfaces when the roll is either not rotating or when the roll is rotating at a speed slower than that required to create and maintain the hydrodynamic oil film 34.

[0006] Oil is continuously discharged from between the journal surface 16 and the bearing surface 20 at both the inboard and outboard ends of the load zone. Oil discharged from the inboard end enters an inner sump 36 surrounded by the seal assembly 28 and the adjacent surfaces of the chocks, bushings, and rolls. Oil discharged from the outboard end enters an outer sump 38 surrounded by the end plate 24 and chocks 22. The sumps 36, 38 are interconnected by one or more passages 40 drilled in the chocks, and the outer sump 38 is connected to a conventional lubrication system (not shown). This lubrication system filters, cools, and recirculates the oil back into the bearing for reintroduction between the bearing surface 20 and the journal surface 16.

[0007] In Figure 3(A), a conventional bushing such as that used in bearings in rolling mills is shown at 300. The bushing has an inner end 301 and an outer end 302. The bushing has (a) a bushing length L B and an inner surface 304 having a cylindrical shape with an inner diameter ID, and the portion of the bushing length that generates the oil film is a fluid dynamic length L H The bushing further comprises (b) an outer surface 303 having a cylindrical shape with an outer diameter OD. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 4,772,137 Summary of the Invention [Problem to be solved by the invention]

[0009] Embodiments of the present invention are improvements over prior art systems and methods. [Means for solving the problem]

[0010] In one embodiment, Option 1 of FIG. 3(B), the present invention provides a bushing (300) for use in a rolling mill bearing, the bushing (300) having an inner end (301) and an outer end (302), the bushing (300) having: (a) a bushing length L B , fluid dynamic pressure length L Hand an inner diameter ID; and (b) an outer surface (303) having an outer diameter OD, the outer surface comprising: (1) a first portion having a length (LB-l), the first portion having a cylindrical shape; and (2) a second portion having a length l (310), the second portion comprising: (i) an undercut portion (312) having an undercut radius r, the undercut portion adjacent an end of the first portion near the inner end. and (ii) an angled portion (308) disposed adjacent to the undercut portion (312), the angled portion (308) tapering from the undercut portion (312) having a radius r to the inner end (301), the tapered portion tapering by δ mm, the angled portion (308) allowing the bushing (300) to deflect with increasing load by a maximum radial deflection δ mm. In one embodiment, δ mm is defined as (bearing load rating {F, metric tons} / fluid dynamic length {LH, mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and preferably 0.025. In this embodiment, the value of l is determined by the following equation: b*fluid dynamic length {LH, mm} H}, and b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%, and preferably 5%.

[0011] In another embodiment, Option 2 of FIG. 3(B), the present invention provides a bushing (300) for use in a rolling mill bearing, the bushing (300) having an inner end (301) and an outer end (302), the bushing (300) having: (a) a bushing length L B , fluid dynamic pressure length L Hand an inner diameter ID; and (b) an outer surface (303) having an outer diameter OD, the outer surface (303) comprising: (1) a first portion having a length (LB-l), the first portion having a cylindrical shape; and (2) a second portion having a length l (310), the second portion comprising an undercut portion (312) having an undercut radius r, the entire length l of the second portion being undercut by an amount δ mm, the second portion being undercut by an amount δ mm allowing the bushing to deflect by a maximum radial deflection δ mm as the load increases. In one embodiment, δ mm is calculated as a function of (bearing load rating {F, metric tons} / fluid dynamic pressure length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, and b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%, and preferably 5%.

[0012] In yet another embodiment, Option 1 of FIG. 3(C), the present invention provides a bearing comprising a bushing (300) for use in a rolling mill, the bushing (300) having an inner end (301) and an outer end (302), the bushing (300) having: (a) a bushing length L B , fluid dynamic pressure length L Hand an inner diameter ID; and (b) an outer surface (303) having an outer diameter OD, the outer surface (303) comprising: (1) a first portion having a length (LB-l), the first portion having a cylindrical shape; and (2) a second portion having a length l (310), the second portion comprising a sloped portion (308) disposed adjacent to the first portion, the sloped portion (308) comprising a tapered portion from the first portion to the inner end (301), the tapered portion tapering by an amount δ mm, the sloped portion (308) allowing the bushing (300) to deflect with increasing load by a maximum radial deflection δ mm, where δ mm is the ratio of (bearing load rating {F, metric tons} / fluid dynamic length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and the value of l is defined as b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%. In one embodiment, δmm is defined as (bearing load rating {F, metric tons} / fluid dynamic length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l.

[0013] In another embodiment, option 2 of FIG. 3(C), the present invention provides a bearing comprising a bushing (300) for use in a rolling mill, the bushing having an inner end (301) and an outer end (302), the bushing (300) having: (a) a bushing length L B , fluid dynamic pressure length L Hand an inner diameter ID; and (b) an outer surface (303) having an outer diameter OD, the outer surface (303) comprising: (1) a first portion of length (LB-l), the first portion having a cylindrical shape; and (2) a second portion of length l (310), the second length l (310) being undercut by an amount δ mm over the entire length l (310) of the second portion, the second portion allowing the bushing to deflect with increasing load at a maximum radial deflection δ mm, where δ mm is calculated as (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and the value of l is defined as b*fluid dynamic length {L H}, where b is selected to be within the range of 20%≦b≦35%. In one embodiment, δ mm is calculated by dividing the bearing load rating {F, metric tons} by the fluid dynamic length (L H , mm))*a, where a is selected to be in the range of 0.02≦a≦0.04, and preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, and b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l.

[0014] In yet another embodiment, Option 1 of FIG. 3(B), the present invention provides a method for reducing temperature rise inside a bushing (300), the bushing (300) being for use in a rolling mill bearing, the bushing (300) having an inner end (301) and an outer end (302), the method comprising: (a) reducing a bushing length L B , inner diameter ID, and fluid dynamic length L H(b) providing an inner surface (304) having a cylindrical shape having a length (LB-l), the outer surface (303) comprising: (1) a first portion having a length (LB-l), the first portion having a cylindrical shape; and (2) a second portion having a length l, the second portion having (i) an undercut portion (312) having an undercut radius r, the undercut portion being disposed adjacent an end of the first portion near the inner end. and (ii) an undercut portion (312), and (ii) an angled portion (308) disposed adjacent to the undercut portion (312), the angled portion (308) comprising a tapered portion from the undercut portion (312) having a radius r to the inner end (301), the tapered portion tapering by δ mm, the angled portion (308) allowing the bushing (300) to deflect by a maximum radial deflection δ mm as the load increases. In one embodiment, δ mm is calculated as: (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%, and is preferably 5%.

[0015] In another embodiment, Option 2 of FIG. 3(B), the present invention is a method for reducing temperature rise inside a bushing (300), the bushing (300) being used in a rolling mill bearing, the bushing having an inner end (301) and an outer end (302), the method comprising: (a) reducing a bushing length L B , fluid dynamic pressure length L Hand (b) providing an outer surface (303) having an outer diameter OD, the outer surface comprising: (1) a first portion of length (LB-l), the first portion having a cylindrical shape, and (2) a second portion of length l (310), the second portion comprising an undercut portion (312) having an undercut radius r, the entire length l of the second portion being undercut by an amount δ mm, the second portion being undercut by an amount δ mm allowing the bushing to deflect by a maximum radial deflection δ mm as the load increases. In one embodiment, δ mm is calculated as a function of (bearing load rating {F, metric tons} / fluid dynamic length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, and b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%, and is preferably 5%.

[0016] In another embodiment, Option 1 of FIG. 3(C), the present invention is a method for reducing temperature rise inside a bushing (300), the bushing (300) being used in a rolling mill bearing, the bushing having an inner end (301) and an outer end (302), the method comprising: (a) reducing a bushing length L B , fluid dynamic pressure length L Hand (b) providing an outer surface (303) having an outer diameter OD, the outer surface comprising: (1) a first portion having a length (LB-l), the first portion having a cylindrical shape; and (2) a second portion having a length l (310), the second portion comprising a sloped portion (308) disposed adjacent the first portion, the sloped portion (308) comprising a tapered portion from the first portion to the inner end (301), the tapered portion tapering by an amount δ mm, the sloped portion (308) allowing the bushing to deflect a maximum radial deflection δ mm as the load increases. In one embodiment, δ mm is calculated as: (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, and b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l.

[0017] In yet another embodiment, Option 2 of FIG. 3(C), the present invention provides a method for reducing temperature rise inside a bushing (300) for use in a rolling mill bearing, the bushing (300) having an inner end and an outer end, the method comprising: (a) reducing a bushing length L B , fluid dynamic pressure length L Hand an inner diameter ID; and (b) providing an outer surface (303) having an outer diameter OD, the outer surface comprising: (1) a first portion of length (LB-l), the first portion having a cylindrical shape; and (2) a second portion of length l (310), the entire length l of the second portion being undercut by an amount δ mm, the second portion allowing the bushing to deflect with increasing load at a maximum radial deflection δ mm. In one embodiment, δ mm is calculated as: (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, and b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l.

[0018] The present disclosure, in accordance with one or more various embodiments, will be described in detail with reference to the following drawings. These drawings are provided for illustrative purposes only and merely illustrate examples of the present disclosure. These drawings are provided to facilitate the reader's understanding of the present disclosure and should not be considered as limiting the breadth, scope, or applicability of the present disclosure. It should be noted that these drawings are not necessarily drawn to scale for clarity and ease of illustration. [Brief explanation of the drawings]

[0019] [Figure 1(A)] 1 illustrates a known fluid dynamic bearing assembly. [Figure 1(B)] 1 illustrates a known fluid dynamic bearing assembly. [Figure 2(A)] FIG. 10 shows the temperature distribution in the sleeve and bushing at the indicated load / speed combinations. [Figure 2(B)]FIG. 10 shows the temperature distribution in the sleeve and bushing at the indicated load / speed combinations. [Figure 2(C)] FIG. 10 shows the temperature distribution in the sleeve and bushing at the indicated load / speed combinations. [Figure 3(A)] 1A-1C show a standard bushing and some embodiments of the present invention showing added features to the bushing. [Figure 3(B)] 1A-1C show a standard bushing and some embodiments of the present invention showing added features to the bushing. [Figure 3(C)] 1A-1C show a standard bushing and some embodiments of the present invention showing added features to the bushing. DETAILED DESCRIPTION OF THE INVENTION

[0020] While the present invention is illustrated and described in a preferred embodiment, the present invention can be embodied in many different configurations. While a preferred embodiment of the present invention is shown in the drawings and described in detail herein, it should be understood that this disclosure is to be interpreted as an illustration of the principles of the invention and the associated functional specifications for its construction, and is not intended to limit the invention to the described embodiment. Many other possible variations within the scope of the invention will occur to those skilled in the art.

[0021] It should be noted that in this description, a reference to "one embodiment" means that the referenced feature is included in at least one embodiment of the present invention. Furthermore, multiple references to "one embodiment" in this specification do not necessarily refer to the same embodiment. However, unless expressly stated otherwise and as would be readily understood by one of ordinary skill in the art, such embodiments are not mutually exclusive. Thus, the present invention can include any and all various combinations and / or integrations of the embodiments described herein.

[0022] By testing bearings under various load and speed combinations, it was found that the oil film thickness on the inside of the bearing (closest to the roll surface) was thinner than that on the outer end. This difference was typically between 0.05 mm and 0.10 mm. Because the oil film was thinner at the inner end, the shear rate of the oil film was higher, which also increased the temperatures of the bushing and sleeve.

[0023] Figures 2(A)-2(C) show graphs of sleeve and bushing temperature distribution at the indicated load / speed combinations (i.e., 50 RPM and 730 tons, 220 RPM and 650 tons, and 290 RPM and 510 tons, respectively). The data was obtained from tests using a full-size 30"-75 KL Morgoil hydrodynamic bearing. Thermocouples were installed in the bushing and sleeve. The sleeve had five thermocouples aligned axially, and as the sleeve rotated, a signal was emitted through the slip ring. The fixed bushing had four rows of four thermocouples, two of which were located + / - 10 degrees from bottom dead center, and the other two rows were located + / - 45 degrees from bottom dead center. In the top diagram of Figure 2(C), the locations of the bushing thermocouples are indicated by white stars, and the sleeve thermocouples are indicated by black circles.

[0024] 2(A)-2(C) show that the temperatures inside the bushing and sleeve are high for all load / speed combinations, especially in the load zone (+ / -10 degrees of the bushing) where the oil film is at its minimum thickness.

[0025] Therefore, there is a need to dynamically adjust the oil film thickness at the inside end of the bearing so that temperatures in that area can be reduced as loads increase, which is important because it can mitigate a severe class of bearing failure called inside edge wipe.

[0026] The prior art is replete with examples of attempts to change the shape of the bearing (static member) to accommodate changes in the shape of the shaft or housing. This invention differs in that the shape of the bearing surfaces of the sleeve and bushing do not change under no-load conditions, where both the sleeve and bushing have cylindrical bearing surfaces. The novel concept instead adds manufacturing features to the bushing to allow it to deflect with increased load, while still controlling the total amount of deflection. For purposes of illustration, the desired maximum radial deflection is calculated as (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {L H , mm})*a, where a is selected to be in the range 0.02≦a≦0.04, and is preferably 0.025.

[0027] The present invention provides a feature of length l on the outside diameter (OD) of the inner end of a bushing (e.g., a bushing used in a rolling mill). A "hinge" feature exists to allow this inner end to flex outward, the total amount of flexing being (bearing load rating {F, metric tons} / fluid dynamic length {L H , mm})*a, where a is selected to be in the range 0.02≦a≦0.04, and is preferably 0.025.

[0028] Figure 3(B) shows one implementation of the present invention. In one embodiment, option 1 of Figure 3(B), the present invention discloses a bushing 300 for use in bearings in rolling mills. The bushing has an inner end 301 and an outer end 302. The bushing has (a) a bushing length L B , fluid dynamic pressure length L H and (b) an inner surface 304 having a cylindrical shape with an inner diameter ID, and an outer surface 303 having an outer diameter OD. The outer surface comprises the following (1) and (2): (1) a first length portion (L B-l). The first portion, having a cylindrical shape, has a first portion 303 (which is a portion of the original outer surface 303). (2) A second length l. The second portion includes (i) an undercut portion 312 disposed adjacent to the end of the first portion near the inner end, where the undercut radius r is preferably defined as 5% of the length l (second length 310), but can optionally be in the range of 2% to 10%. The second portion further includes (ii) a second tapered portion 308 disposed adjacent to the undercut portion. The second tapered portion allows the bushing to deflect with a maximum radial deflection δ as the load increases, where l is preferably 25%*L. H (fluid dynamic length), but can optionally be in the range of 20% to 35%. Furthermore, the value of δ can preferably be calculated as (bearing load rating {F, metric tons} / fluid dynamic length {LH, mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. Alternatively, in Option 2 of FIG. 3(B), instead of a tapered section from hinge 312 to the inner end, the overall length l is undercut by an amount δ, calculated in a manner similar to Option 1.

[0029] In another embodiment, Option 1 of Figure 3(C), the present invention discloses a bushing 300 for use in bearings in rolling mills. The bushing has an inner end 301 and an outer end 302. The bushing has (a) a length L B and diameter ID, and (b) outer surface 303 having an outer diameter OD. This outer surface comprises the following (1) and (2): (1) a first length portion (L B(1) a second length l. This second length l includes a tapered portion 308 disposed adjacent to the first portion 303, which allows the bushing to deflect to a maximum radial deflection δ as the load increases. Alternatively, in Option 2 of FIG. 3(C), as an alternative to the tapered portion of the second tapered portion 308, the overall length l is undercut by an amount δ calculated in a manner similar to Option 1 above.

[0030] The bearing surface itself is cylindrical and deflects under load. This deflection can be controlled by manipulating the stiffness of the deflection features. The length l is the hydrodynamic bearing length L H is a function of

[0031] In one embodiment, FIG. 3(B) Option 1, the present invention provides a bushing for use in bearings in rolling mills. The bushing has an inner end and an outer end. The bushing has: (a) a bushing length L B , fluid dynamic pressure length L H and (b) an inner surface having a cylindrical shape with an inner diameter ID, and an outer surface having an outer diameter OD. The outer surface comprises the following (1) and (2): (1) a first length portion (L B -l). The first portion has a conical shape and includes a first portion. (2) a second length portion l. The second portion includes the following (i) and (ii): (i) an undercut portion having an undercut radius r. The undercut portion is located adjacent to an end of the first portion near the inner end. (ii) a tapered portion located adjacent to the undercut portion. The tapered portion allows the bushing to deflect at a maximum radial deflection δ as the load increases. In one embodiment, δ is calculated as (bearing load rating {F, metric tons} / fluid dynamic length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. In this embodiment, the length (L B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%, and is preferably 5%.

[0032] In another embodiment, Option 2 of Figure 3(B), the present invention provides a bushing for use in bearings in rolling mills. The bushing has an inner end and an outer end. The bushing has (a) a bushing length L B , fluid dynamic pressure length L H and an inner surface of cylindrical shape having an inner diameter ID, and (b) an outer surface of outer diameter OD. The outer surface comprises (1) a first portion of length (LB-l), the first portion having a cylindrical shape, and (2) a second length l. The second portion has an undercut radius r, and the entire length l of the second portion is undercut by an amount δ. In one embodiment, δ is defined as (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {LH, mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is determined by the following equation: b*Fluid Dynamic Length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%, and preferably 5%.

[0033] In yet another embodiment, Option 1 of Figure 3(C), the present invention provides a bushing for use in bearings in rolling mills. The bushing has an inner end and an outer end. The bushing has (a) a bushing length L B , fluid dynamic pressure length L Hand an inner surface having a cylindrical shape with an inner diameter ID, and (b) an outer surface having an outer diameter OD. The outer surface comprises: (1) a first portion of length (LB-l), the first portion having a cylindrical shape; and (2) a second portion of length l having a tapered portion disposed adjacent the first portion. The second tapered portion allows the bushing to deflect with a maximum radial deflection δ as the load increases. In one embodiment, δ is defined as (bearing load rating {F, metric tons} / fluid dynamic length {LH, mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is determined by the following equation: b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l.

[0034] In another embodiment, Option 2 of Figure 3(C), the present invention provides a bushing for use in bearings in rolling mills. The bushing has an inner end and an outer end. The bushing has (a) a bushing length L B , fluid dynamic pressure length L H and an inner surface of cylindrical shape having an inner diameter ID, and (b) an outer surface of outer diameter OD. The outer surface comprises (1) a first portion of length (LB-l), the first portion having a cylindrical shape, and (2) a second length l. The entire length l of the second portion is undercut by an amount δ. In one embodiment, δ is defined as (bearing load rating {F, metric tons} / fluid dynamic length {LH, mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and preferably 0.025. In this embodiment, the value of l is determined by the following equation: b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. In this embodiment, the length (L B -l)>length l.

[0035] In yet another embodiment, Option 1 of Figure 3(B), the present invention provides a method for reducing temperature rise inside a bushing used in a bearing in a rolling mill, the bushing having an inner end and an outer end, the method comprising: (a) a bushing length L B , inner diameter ID, and fluid dynamic length L H (b) providing an outer surface, the outer surface including (1) a first length (L) having a cylindrical shape; B -l), and (2) a second length l. The second length l comprises (i) an undercut portion having an undercut radius r located adjacent an end of the first portion near the inner end, and (ii) a tapered portion located adjacent the undercut portion. The tapered portion allows the bushing to deflect with a maximum radial deflection δ as the load increases. In one embodiment, δ is calculated as (bearing load rating {F, metric tons} / fluid dynamic length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, where b is selected in the range of 20%≦b≦35%, and is preferably 25%. B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected in the range 2%≦c≦10%, and is preferably 5%.

[0036] In another embodiment, Option 2 of Figure 3(B), the present invention provides a method for reducing temperature rise inside a bushing used in bearings in rolling mills, the bushing having an inner end and an outer end, the method comprising: (a) a bushing length L B , fluid dynamic pressure length L H and (b) providing an inner surface having a cylindrical shape with an inner diameter ID, and (c) providing an outer surface having an outer diameter OD. The outer surface includes: (1) a first length (L) having a cylindrical shape;B -l), and (2) a second length l. The second length l has an undercut radius r, and the entire length l of the second length l is undercut by an amount δ. In one embodiment, δ is calculated as (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. In this embodiment, the length (L B -l)>length l. In this embodiment, the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%, and is preferably 5%.

[0037] In yet another embodiment, Option 1 of Figure 3(C), the present invention provides a method for reducing temperature rise inside a bushing used in a bearing in a rolling mill, the bushing having an inner end and an outer end, the method comprising: (a) providing an inner surface having a cylindrical shape, the inner surface extending over a bushing length L; B , fluid dynamic pressure length L H , and an inner diameter ID; and (b) an outer surface having an outer diameter OD. The outer surface comprises: (1) a first portion of length (LB-l), the first portion having a cylindrical shape; and (2) a second length l comprising a tapered portion disposed adjacent the first portion. The second tapered portion allows the bushing to deflect at a maximum radial deflection δ as the load increases. In one embodiment, δ is calculated as: (Bearing Load Rating {F, metric tons} / Fluid Dynamic Length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and is preferably 0.025. In this embodiment, the value of l is defined as b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. In this embodiment, the length (LB -l)>length l.

[0038] In another embodiment, Option 2 of Figure 3(C), the present invention provides a method for reducing temperature rise inside a bushing used in bearings in rolling mills, the bushing having an inner end and an outer end, the method comprising: (a) a bushing length L B , fluid dynamic pressure length L H and (b) providing an inner surface of a cylindrical shape having an inner diameter ID, and (c) providing an outer surface having an outer diameter OD, the outer surface comprising: (1) a first length (L) of the cylindrical shape; B -l), and (2) a second length portion l. The entire length l of this second portion is undercut by an amount δ. In one embodiment, δ is defined as (bearing load rating {F, metric tons} / fluid dynamic length {LH, mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and preferably is 0.025. In this embodiment, the value of l is determined by the following equation: b*fluid dynamic length {L H}, where b is selected to be in the range of 20%≦b≦35%, and is preferably 25%. In this embodiment, the length (L B -l)>length l.

[0039] conclusion In the above-described embodiments, a system and method for effectively achieving a reduction in bearing temperature through improved bushings has been presented. While various preferred embodiments have been shown and described, it will be understood that such disclosure is not intended to limit the invention, but rather to cover all modifications within the spirit and scope of the invention as defined in the appended claims. [Explanation of symbols]

[0040] 10 rolls 12 Neck Section 14 sleeve 16 Journal Surface 18 Bush 20 Internal bearing surface 22 Chock 24 End Plate 26 Cover 28 Seal Assembly 29 Passage 30 supply port 32 Reboa 34 Oil slick 36 Inner sump 38 Outer sump 40 Passage 300 bushings 301 Inner end 302 Outer edge 303 Outer surface, first portion 304 Inner surface 308 Inclined section, second inclined section 310 Second Length 312 Undercut part, hinge

Claims

1. A bushing (300) for use in a rolling mill bearing, having an inner end (301) and an outer end (302), said bushing (300) comprising: (a) Bush length L B , fluid dynamic pressure length L H and an inner surface (304) having a cylindrical shape with an inner diameter ID; (b) an outer surface (303) having an outer diameter OD, said outer surface comprising: (1) Length (L B -l) a first part having a cylindrical shape, and (2) The second part of length l(310) an outer surface comprising: In the bushing (300), the second portion comprises: (i) an undercut portion (312) having an undercut radius r, the undercut portion being disposed adjacent an end of the first portion near the inner end; and (ii) a sloped portion (308) disposed adjacent to the undercut portion (312), the sloped portion (308) comprising a tapered portion from the undercut portion (312) having a radius r to the inner end (301), the tapered portion tapering by δ mm; Equipped with The angled portion (308) allows the bushing (300) to deflect with a maximum radial deflection δ mm as the load increases.

2. 2. The bushing (300) of claim 1, wherein δmm is defined as (bearing load rating {F, metric tons} / fluid dynamic length {LH, mm})*a, where a is selected to be in the range of 0.02≦a≦0.

04.

3. 3. The bushing (300) of claim 2, wherein a is 0.

025.

4. The value of l is b*fluid dynamic length {L H 3. The bushing (300) of claim 2, wherein b is selected to be in the range 20%≦b≦35%.

5. 5. The bushing (300) of claim 4, wherein b is 25%.

6. 2. The bushing (300) of claim 1, wherein the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%.

7. 7. The bushing (300) of claim 6, wherein c is 5%.

8. Length (L B 2. The bushing (300) of claim 1, wherein length l is greater than length l.

9. 2. The bushing (300) of claim 1, wherein a sleeve is disposed about the inner surface of the bushing (300), and a gap exists between the bushing (300) and an outer surface of the sleeve, the gap being configured to maintain a hydrodynamically maintained oil film.

10. 10. The bushing (300) of claim 9, wherein the bushing (300) is secured in a chock.

11. 11. The bushing (300) of claim 10, wherein an end plate and cover are provided at the outer end (302) to seal the bushing (300) and the sleeve.

12. A bushing (300) for use in a rolling mill bearing, said bushing (300) having an inner end (301) and an outer end (302), said bushing (300) comprising: (a) Bush length L B , fluid dynamic pressure length L H and an inner surface (304) having a cylindrical shape with an inner diameter ID; (b) an outer surface (303) having an outer diameter OD, said outer surface (303) comprising: (1) Length (L B -l) a first portion, said first portion having a cylindrical shape; and (2) The second part of length l(310) an outer surface (303) comprising: In the bushing (300), the second portion comprises an undercut portion (312) having an undercut radius r, and the entire length l of the second portion is undercut by an amount δ mm; The bushing (300), wherein the second portion is undercut by the amount δ mm, allowing the bushing to deflect with a maximum radial deflection δ mm as the load increases.

13. δmm is (bearing load rating {F, metric tons} / fluid dynamic pressure length (L H 13. The bushing (300) of claim 12, wherein the radius of curvature is defined as (mm)*a, where a is selected to be in the range of 0.02≦a≦0.

04.

14. 14. The bushing (300) of claim 13, wherein a is 0.

025.

15. The value of l is b*fluid dynamic length {L H 14. The bushing (300) of claim 13, wherein b is selected to be in the range 20%≦b≦35%.

16. 16. The bushing (300) of claim 15, wherein b is 25%.

17. 13. The bushing (300) of claim 12, wherein the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%.

18. 18. The bushing (300) of claim 17, wherein c is 5%.

19. Length (L B 13. The bushing (300) of claim 12, wherein length l is greater than length l.

20. A bearing comprising a bushing (300) for use in a rolling mill, the bushing (300) having an inner end (301) and an outer end (302), the bushing (300) comprising: (a) Bush length L B , fluid dynamic pressure length L H and an inner surface (304) having a cylindrical shape with an inner diameter ID; (b) an outer surface (303) having an outer diameter OD, said outer surface comprising: (1) Length (L B -l) a first portion, said first portion having a cylindrical shape; and (2) The second part of length l(310) an outer surface (303) comprising: A bearing comprising: the second portion comprises an inclined portion (308) disposed adjacent to the first portion, the inclined portion (308) comprising a tapered portion from the first portion to the inner end (301), the tapered portion tapering by an amount δ mm; The angled portion (308) allows the bushing (300) to deflect with a maximum radial deflection δ mm as the load increases; δmm is the ratio of (bearing load rating {F, metric tons} / fluid dynamic pressure length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and the value of l is defined as b*fluid dynamic length {L H }, and b is selected to be in the range 20%≦b≦35%.

21. 21. The bearing of claim 20, wherein a is 0.

025.

22. 22. The bearing of claim 21, wherein b is 25%.

23. Length (L B 21. The bearing of claim 20, wherein -l)>length l.

24. A bearing comprising a bushing (300) for use in a rolling mill, the bushing having an inner end (301) and an outer end (302), the bushing (300) comprising: (a) Bush length L B , fluid dynamic pressure length L H and an inner surface (304) having a cylindrical shape with an inner diameter ID; (b) an outer surface (303) having an outer diameter OD, said outer surface comprising: (1) Length (L B -l) a first portion, said first portion having a cylindrical shape; and (2) The second part of length l(310) an outer surface comprising: A bearing comprising: the overall length l (310) of the second portion is undercut by an amount δ mm, the second portion allowing the bushing to deflect by a maximum radial deflection δ mm as the load increases; δmm is the ratio of (bearing load rating {F, metric tons} / fluid dynamic pressure length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and the value of l is defined as b*fluid dynamic length {L H }, and b is selected to be in the range 20%≦b≦35%.

25. 25. The bearing of claim 24, wherein a is 0.

025.

26. 25. The bearing of claim 24, wherein b is 25%.

27. Length (L B 25. The bearing of claim 24, wherein -l)>length l.

28. 1. A method for reducing temperature rise inside a bushing (300), the bushing (300) being for use in a rolling mill bearing, the bushing (300) having an inner end (301) and an outer end (302), the method comprising: (a) Bush length L B , inner diameter ID, and fluid dynamic length L H providing an inner surface (304) having a cylindrical shape having: (b) providing an outer surface (303), said outer surface (303) comprising: (1) Length (L B -l) a first portion, said first portion having a cylindrical shape; and (2) a second portion of length l, said second portion comprising: (i) an undercut portion (312) having an undercut radius r, the undercut portion (312) being disposed adjacent an end of the first portion near the inner end; and (ii) a sloped portion (308) disposed adjacent to the undercut portion (312); A second portion comprising: Equipped with the inclined portion (308) comprises a tapered portion from the undercut portion (312) having a radius r to the inner end (301), the tapered portion tapering by δ mm; The inclined portion (308) allows the bushing (300) to deflect with a maximum radial deflection δ mm as the load increases. A method comprising:

29. δmm is the ratio of (bearing load rating {F, metric tons} / fluid dynamic pressure length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and the value of l is defined as b*fluid dynamic length {L H 29. The method of claim 28, wherein b is defined as:} and b is selected to be in the range 20%≦b≦35%.

30. Length (L B 29. The method of claim 28, wherein -l)>length l.

31. 29. The method of claim 28, wherein a is 0.

025.

32. 29. The method of claim 28, wherein b is 25%.

33. 29. The method of claim 28, wherein the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%.

34. 29. The method of claim 28, wherein c is 5%.

35. 1. A method for reducing temperature rise inside a bushing (300), the bushing (300) being for use in a rolling mill bearing, the bushing (300) having an inner end (301) and an outer end (302), the method comprising: (a) Bush length L B , fluid dynamic pressure length L H and providing an inner surface (304) having a cylindrical shape with an inner diameter ID; (b) providing an outer surface (303) having an outer diameter OD, said outer surface comprising: (1) Length (L B -l) a first portion, said first portion having a cylindrical shape; and (2) The second part of length l(310) the second portion comprises an undercut portion (312) having an undercut radius r, and the entire length l of the second portion is undercut by an amount δ mm; the second portion being undercut by the amount δ mm allows the bushing to deflect by a maximum radial deflection δ mm as the load increases; A method comprising:

36. δmm is the ratio of (bearing load rating {F, metric tons} / fluid dynamic pressure length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and the value of l is defined as b*fluid dynamic length {L H 36. The method of claim 35, wherein b is defined as:}, and b is selected to be in the range 20%≦b≦35%.

37. 37. The method of claim 36, wherein a is 0.

025.

38. 37. The method of claim 36, wherein b is 25%.

39. 37. The method of claim 36, wherein the undercut radius r is defined as c*length l, where c is selected to be in the range 2%≦c≦10%.

40. 40. The method of claim 39, wherein c is 5%.

41. Length (L B 37. The method of claim 36, wherein -l) > length l.

42. 1. A method for reducing temperature rise inside a bushing (300), the bushing (300) being for use in a rolling mill bearing, the bushing (300) having an inner end (301) and an outer end (302), the method comprising: (a) Bush length L B , fluid dynamic pressure length L H and providing an inner surface (304) having a cylindrical shape with an inner diameter ID; (b) providing an outer surface (303) having an outer diameter OD, said outer surface comprising: (1) Length (L B -l) a first portion, said first portion having a cylindrical shape; and (2) The second part of length l(310) Equipped with the second portion comprises an angled portion (308) disposed adjacent to the first portion, the angled portion (308) comprising a tapered portion from the first portion to the inner end (301), the tapered portion tapering by an amount δ mm, the angled portion (308) allowing the bushing to deflect by a maximum radial deflection of δ mm as the load increases; A method comprising:

43. δmm is the ratio of (bearing load rating {F, metric tons} / fluid dynamic pressure length {L H , mm})*a, where a is selected to be in the range of 0.02≦a≦0.04, and the value of l is defined as b*fluid dynamic length {L H 43. The method of claim 42, wherein b is defined as:}, and b is selected to be in the range 20%≦b≦35%.

44. 44. The method of claim 43, wherein a is 0.

025.

45. 44. The method of claim 43, wherein b is 25%.

46. Length (L B 43. The method of claim 42, wherein -l)>length l.

47. 1. A method for reducing temperature rise inside a bushing (300), the bushing (300) being for use in a rolling mill bearing, the bushing (300) having an inner end and an outer end, the method comprising: (a) Bush length L B , fluid dynamic pressure length L H and providing an inner surface (304) having a cylindrical shape with an inner diameter ID; (b) providing an outer surface (303) having an outer diameter OD, said outer surface comprising: (1) Length (L B -l) a first portion, said first portion having a cylindrical shape; and (2) The second part of length l(310) Equipped with the entire length 1 of the second portion is undercut by an amount δ mm, the second portion allowing the bushing to deflect with a maximum radial deflection δ mm as the load increases; A method comprising:

48. δmm is defined as (bearing load rating {F, metric tons} / fluid dynamic length {LH, mm})*a, where a is selected to be in the range 0.02≦a≦0.04, and the value of l is b*fluid dynamic length {L H 48. The method of claim 47, wherein b is defined as:}, and b is selected to be in the range 20%≦b≦35%.

49. 49. The method of claim 48, wherein a is 0.

025.

50. 49. The method of claim 48, wherein b is 25%.

51. Length (L B 48. The method of claim 47, wherein -l) > length l.

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