WO2002038428A1

WO2002038428A1 - Stabilized seal wear ring

Info

Publication number: WO2002038428A1
Application number: PCT/US2001/043712
Authority: WO
Inventors: Peter W. Ingham; Samuel R. Williams
Original assignee: The Timken Company
Priority date: 2000-11-08
Filing date: 2001-11-06
Publication date: 2002-05-16
Also published as: AU2002226942A1

Abstract

A seal wear ring (12, 14), that forms part of a bearing assembly (B) in which a journal (2) rotates, includes an steel sleeve (50) having a cylindrical sealing surface (54) that is presented outwardly, a cylindrical positioning surface (62) that is presented inwardly, and a rib (64) that projects radially inwardly past the positioning surface. In addition, the wear ring has a polymer insert (52, 90) that is compressed between the surface of the journal and the cylindrical positioning surface of the sleeve. The insert stabilizes the sleeve so that its sealing surface remains concentric with the journal. As a consequence, the elastomeric seal element (46) of a seal (30) which surrounds the wear ring establishes a highly effective fluid barrier with the sealing surface of the sleeve and has enhanced longevity.

Description

STABILIZED SEAL WEAR RING Technical Field

This invention relates in general to fluid barriers and, more particularly, to a seal wear ring that is stabilized to remain concentric with that on which it is mounted and to a bearing assembly having such a wear ring. Background Art

The typical rail car axle has at its ends journals which rotate in antifriction bearings, and those bearings often take the form of double row tapered roller bearings. This type of bearing has a unitary outer race, called a cup, and two inner races, called cones, as well as tapered rollers arranged in tow rows between the cones and the cup, there being a separate row around each cone. The cones fit over the journal between two wear rings which in turn are captured between a backing ring and an end cap. The cup at its ends is fitted with seals which have elastomeric seal elements provided with lips that contact the wear rings and thus establish dynamic fluid barriers at the ends of the bearing to retain lubricants in and exclude contaminants from the interior of the bearing. In order for the seals to operate effectively, the seal wear ring must remain concentric with respect to the journal. Without this concentricity the seal lips will wear rapidly and eventually separate from the wear ring. But conventional wear rings sometimes lose their concentricity, even though concentricity may exist at the time of installation. In this regard, the conventional wear ring has an inwardly directed rib at one of its ends, and at that rib the wear ring fits over the journal with an interference fit. The rib for the inboard wear ring lies adjacent to the end of the inboard cone - a location where the journal experiences perhaps its greatest flexure as the axle rotates with a load transferred to it through the bearing. The flexure in turn produces fretting which wears away the journal and, likewise, the bore in the rib of the wear ring. In time the inboard wear ring works loose and no longer remains concentric to the journal, thus diminishing the longevity and effectiveness of the seal.

Rail car axles are expensive, so railroads will often keep an axle in service after its journals have experienced fretting. Sometimes a groove produced by the fretting is filled by plating. In the alternative, other means may be used to maintain the inboard wear ring concentric with the axle.

Summary of the Invention

The present invention resides in a seal wear ring that includes a steel sleeve having an outwardly presented sealing surface and an inwardly presented positioning surface and also an inwardly directed rib at one end. In addition, the wear ring has an insert that fits within the sleeve where it is against the positioning surface. The insert is formed from a resilient material which will deform to accommodate a narrow space between a journal and the surrounding positioning surface of the sleeve. The invention also resides in a bearing assembly that includes the wear ring.

Brief Description of Drawings

Fig. 1. Is a longitudinal sectional view of an axle journal and bearing assembly equipped with wear rings constructed in accordance with and embodying the present invention;

Fig. 2. is an fragmentary sectional view, enlarged, of the wear ring and the inboard cone and backing ring between which the wear ring is located on the journal; Fig. 3 is an fragmentary sectional view, enlarged, of the wear ring; and

Fig. 4 is an exploded perspective view of the wear ring provided with a modified insert.

Best Mode for Carrying Out the Invention Referring now to the drawings, an axle A (Fig. 1) is confined at its end in a bearing assembly B and rotates about an axis X within the bearing assembly B. Actually, the bearing assembly B fits over a cylindrical journal 2 at the end of the axle A, and the journal 2 merges into the remainder of the axle A at a fillet 4. The journal 2 has a cylindrical surface 6 that runs from the fillet 4 out to a short beveled surface 8 at its opposite end. The bearing assembly B includes a double row tapered roller bearing 10, inboard and outboard wear rings 12 and

14, a backing ring 16, and an end cap 18. At the inboard end of the bearing 10, the journal 2 may have a shallow groove 20 (Fig. 2) that opens out of the cylindrical surface 6, it having been caused by fretting.

The bearing 10 is conventional and typical of the type used with rail car axles. It is furnished as a prelubricated and preset unit and includes (Fig. 1) an outer race in the form of a double cup 22, an inner race in the form of inboard and outboard cones 24, tapered rollers 26 arranged in two rows between the cup 22 and cones 24, there being a separate row around each cone 24, a spacer 28 between the two cones 24, and seals 30 fitted to the cup 22 for closing the ends of the bearing

10. The seals 30 establish fluid barriers along the wear rings 12 and 14.

The double cup 22 has tapered raceways 32 which are presented inwardly toward the axis X. At their large ends the raceways 32 open into end bores 34 which in turn open out of the ends of the cup 22. Each cone 24 has a tapered raceway 36 which is presented outwardly and a thrust rib 38 at the large end of its raceway 36. On the end of its thrust rib 38, each cone 24 has a back face 40. The tapered rollers 26 lie between the raceways 32 and 36 on the cup 22 and the cones 24, respectively, where the thrust ribs 38 prevent them from migrating up the raceways 32 and 36 and out of the annular space between the cup 22 and cones 24. The spacer 28 establishes the spacing between the two cones 24, and that in turn determines the setting for the bearing 10. By reason of the tapered geometry, the cup 22 cannot be displaced axially with respect to the cones 24, but the cones 24 are free to rotate in the cup 22 about the axis X. The cones 24 fit over the cylindrical surface 6 of the journal 2 with an interference fit, whereas the cup 22 fits into a housing (not shown) that in turn is fitted to the side frame of a rail car truck.

The double cup 22 carries the two seals 30. Each includes a stamped metal case 44 and an elastomeric seal element 46 which is bonded to the case 44 and, for the most part, is enclosed within the case 44. The case 44 of the inboard seal 30 is pressed into the inboard end bore 34 of the double cup 22, whereas the case 44 of the outboard seal 30 is pressed into the outboard end bore 34. With the cases 44 so fitted to the cup 22, the elastomeric seal elements 46 lie beyond the back faces 40 of the two cones 24 where they are presented inwardly toward the journal 2 and the axis X. Indeed, the elastomeric seal elements 46 of the seals 30 have lips which bear against the seal wear rings 12 and 14. The cases 44, being fitted to the cup 22, are concentric to the journal 2. To operate effectively with longevity, the seal elements 46 should remain concentric to the journal 2, and thus the wear rings 12 and 14 must not cause the seal elements 46 to undergo radial displacements during the operation of the bearing assembly B.

Each wear ring 12 and 14 includes (Figs. 2 & 3) a steel sleeve 50 and a polymer insert 52 that is within the sleeve 50. The sleeve 50 may be a conventional wear ring, and it may be either new or used. If new, it should fit over the journal with an interference fit. If used, it may be worn by fretting to the extent that it fits loosely over the journal 2. On the other hand, the sleeve 50 may be formed new such that it fits loosely over the journal 2. In any event, the insert 52 fits tightly over the journal 2 and within the sleeve 50 and maintains the sleeve 50 snugly around the journal 2 and concentric with respect to outer surface 6 of the journal 2 as well.

Resembling a traditional wear ring, the sleeve 50 has (Fig. 3) on its exterior a cylindrical sealing surface 54 and a slightly beveled end surface 56, both of which are presented outwardly away from the axis X. The two surfaces 54 and 56 merge between the ends of the sleeve 50, with the sealing surface 54 being the longer of the two. The sealing surface 54 leads out to an end face 58, whereas the slightly beveled surface 56 leads out to another end face 60. Both end faces 58 and 60 are squared off with respect to the axis X. The cylindrical sealing surface 54 surrounds a cylindrical positioning surface 62 which is presented inwardly and is of somewhat greater length. It too leads out to the end face 58. The beveled end surface 56, apart from surrounding the opposite end of the cylindrical positioning surface 62, also surrounds a rib 64 that is directed inwardly from the surface 62. The rib 64 forms a cylindrical bore 66 in the sleeve 50, its diameter being less than the diameter of the positioning surface 62. One end of the rib 64 lies along the end face 60. The other end of a rib 64 lies along a beveled intervening surface 68 through which the cylindrical surface 62 opens into the bore 66. The sealing surface 54, the beveled surface 56, and the positioning surface 62 are concentric as is the surface of the bore 66, with their common center being the axis X.

The diameter of the cylindrical positioning surface 62 on the sleeve 50 exceeds the diameter of the journal 2, so that annular space exists between the surface 62 and the surface 6 of the journal 2 (Fig. 2). The diameter of the bore 66 on the rib 64 may be less than the diameter of the cylindrical surface 6 on journal 2, so that the sleeve 50 must be pressed over the journal 2. Indeed, when the bore 66 is so sized, an interference fit will exist between the rib 64 of the sleeve 50 and the cylindrical surface 6 of the journal 2, unless the journal 2 contains a groove 20 in the region of the rib 64 as a consequence of fretting (Fig. 2). On the other hand, the bore 66 in the rib 64 may be of a diameter greater than the diameter of the cylindrical surface on the journal 2, in which event the sleeve 50 will fit loosely over the journal 2.

The polymer insert 52 fits tightly between the sleeve 50 and the journal 2 with its one end against the beveled intermediate surface 68 of the sleeve 50 and its other end offset somewhat from the end face 58 at the other end of the sleeve 50. Its length exceeds one-half the length of the sleeve 50. The insert 52 has a cylindrical exterior surface 72 which bears snugly against the cylindrical positioning surface 62 of the sleeve 50. The insert 52 also has a cylindrical interior surface 74 which, when the insert 52 is in the sleeve 50, but the wear ring 14 or 16 is removed from the journal 2, has a diameter less than the diameter of the cylindrical surface 6 on the journal 2. Thus, an interference fit exists between the insert 52 and the surface 6 of the journal 2, and this serves to position the sleeve 50 firmly on the journal 2 with the centerline of its cylindrical sealing surface 54 coinciding with the axis X.

In order to accommodate the interference fit with the journal 2, the polymer of the insert 52 should have the capacity to flow, and in order to flow, it must be resilient. It should also have a low coefficient of friction against steel, and certainly less than steel against steel. High density polyethylene (HDPE) or other suitable polymers may be used for the insert 52. HDPE has a density of 0.956 g/cm³, tensile strength at yield of 4600 lbs/in², tensile elongation at yield of about 800%, and Shore D hardness of 69

The backing ring 16 fits over the journal 2 and seats against the fillet 4 at the end of the journal 2 (Fig. 2). The ring 16 has a contoured interior surface 76 which conforms to the surface of the fillet 4, so that the fillet 4 centers the backing ring 16 on the journal 2. Beyond the large end of the contoured interior surface 76, the backing ring 16 may fit snugly around the axle A ("fitted" backing ring as illustrated) or the ring 16 may end at the large end of the surface 76 and the large end of the fillet 4 (nonfitted backing ring - not illustrated) The backing ring 16 also has a short end bore 78 which opens away from the contoured surface 76, and is large enough to receive the end of the sleeve 50 for the wear ring 12 with a slight interference fit. Thus, the diameter of the bore 78 is only slightly smaller than the diameter of the cylindrical sealing surface 54 on the sleeve 50. The depth of the end bore 78 is about the same as the offset between the end of the insert 52 and the end face 58 of the sleeve 50. The inboard wear ring 12 fits around the journal 2 with one end of its sleeve 50, that is the end at the end face 58, located in the short end bore 78 of the backing ring 16 and its other end face 60 abutting the back face 40 of the inboard cone 24 (Figs. 1 & 2). The inboard seal 30 surrounds the wear ring 12 and its elastomeric seal element 46 bears against the cylindrical sealing surface 54 of the sleeve 50.

The outboard wear ring 14 likewise fits over the journal 2, and the end face 60 of its sleeve 50 abuts the back face 40 of the outboard cone 24 (Fig. 1). The other end face 58 of the sleeve 50 lies slightly beyond the outboard end of the journal 2. The outboard seal 30 surrounds the outboard wear ring 14, and its elastomeric seal element 46 bears against the cylindrical sealing surface 54 on the sleeve 50 of the wear ring 14.

The end cap 18 extends across the outboard end of the journal 2 where it is secured to the journal 2 with cap screws 80 (Fig. 1). It has a shallow recess 82 which receives the end of the sleeve 50 for the outboard wear ring 14. Thus, when the cap screws 80 are tightened, the two cones 24, and the spacer 28 of the bearing 10, and the sleeves 50 of the two wear rings 12 and 14 are all clamped tightly together between the backing ring 16 and the end cap 18.

When the axle A rotates, its journal 2 turns on the bearing 6. Actually, the cones 24 rotate with the journal 2, while the double cup 22 remains fixed. The tapered rollers 26 roll along the raceways 26 and 32 of the cup 22 and cones 24, respectively, and thus accommodate the rotation of the journal 2 with minimal friction. The wear rings 12 and 14 rotate with the cones 24 and journal 2 and within the seals 30. Indeed, the elastomeric seal elements 46 bear against the cylindrical sealing surfaces 54 on the steel sleeve 50 of the wear rings 12 and 14 and form dynamic fluid barriers along the sleeves 50. The barriers so formed retain a lubricant within the annular space between the cup 22 and cones 24 and further exclude contaminants from that space. The inserts 52 maintain their respective sleeves 50 concentric with respect to the cylindrical surface 6 of the journal 2. Thus, as the wear rings 12 and 14 revolve, the cylindrical sealing surfaces 54 on their sleeves 50 display no runout, that is to say, the centerlines of the sealing surfaces 54 remain coincident with the axis X. As a consequence, the rotation does not distort the elastomeric seal elements 46 of the seals 30 and the seal elements 46 experience minimum wear.

The wear rings 12 and 14 work equally well with hydrodynamic lubrication seals such as those disclosed in U.S. Patent 4,819,949 and U.S. Patent 5,024,449. These seals have primary lips which encircle wear rings, but do not actually contact the wear rings, there being slight gaps between the sealing surfaces of the wear rings and the primary lips. The lips contain formations for pumping lubricant back into the interior of a bearing that is between the wear rings. The seals function best when the small gaps between their primary lips and the sealing surfaces of the wear rings are uniform, and the inserts 52 serve to keep the steel sleeves 50 and the sealing surfaces 54 on the sleeves 50 concentric with the journal 2 and hence eliminate variations in the gaps. Likewise, the wear rings 12 and 14 function well with other minimal contact or low torque seals. A heavy load transferred through the bearing 10 to the axle A will cause the journal 2 to flex, with the greatest flexure occurring generally in the regions of the back face 40 for the inboard cone 24. If the inboard wear ring 12 is installed with its rib 64 contacting the journal 2, some fretting will occur at the cylindrical surface of the bore 66 and at the cylindrical surface 6 of the journal 2, but the sleeve 50 of the wear ring 12 will not work loose, because the insert 52 supports the sleeve 50 on the journal 2. No fretting occurs between the insert 52 and the journal 2, inasmuch as a low coefficient of friction exists between the polymer of the insert 52 and the steel of the journal 2, and besides the polymer of the insert 52, is too soft to cause fretting. For this very reason, no fretting will occur if the inboard wear ring 12 is installed with its rib 64 separated from the cylindrical surface 6 of the journal 2 by reason of having been worn through previous use, or by reason of a groove 20 having been worn into the journal 2 by fretting from an earlier conventional wear ring (Fig. 2), or by reason of the bore 66 having been formed oversize. If the journal 2 contains an annular groove in its otherwise cylindrical surface 6 as a consequence of fretting, the journal 2 need not be plated to remove the groove, because the insert 52 keeps the wear surface 54 of the sleeve 50 concentric to the surface 6 of the spindle 2, even when a groove is present. By the same token, a wear ring having a fretted bore 66 in its rib 64 need not be replaced, since the insert 52, not the rib 64, centers the sleeve 50 on the journal 2.

A modified insert 90 (Fig. 4) is formed from a flat strip of polymer that is transformed into a circular configuration by bringing its ends together within the sleeve 50. Actually, the end edges of the strip do not meet, but instead a slight gap 92 exists between them, and that gap 92 may form a vent through the sleeve 50 and into the backing ring 16 which should contain a vent fitting if the vent in the insert 90 is to be effective. The arrangement equalizes pressure between the interior of the bearing 10 and the exterior. The gap 92 also provides a volume for accommodating plastic flow of the insert 90 when it is compressed between the positioning surface 62 at the sleeve 50 and the cylindrical surface 6 of the journal 2.

Actually, the polymer strip which forms the insert 90 does not naturally conform precisely to the cylindrical positioning surface 62 of the sleeve 50. On each side of the gap 92 between its two end edges, the insert 90 tends to separate slightly from the positioning surface of the sleeve 50.

To facilitate installation of the strip-type insert 90 in the sleeve 50, a pair of transfer tapes 94, each having adhesive on both of its faces, are placed against exterior surface 72 of the insert 90 with one of the faces on each adhered to the exterior surface 72. A release strip initially covers the adhesive on the opposite faces of the two tapes 94. Prior to installing the strip-type insert 90 in the sleeve 50, the release strips are peeled off the tapes 94, exposing the adhesive on the outwardly presented faces of the tapes 94. Thereupon the insert 90 is contracted to a diameter slightly smaller than the diameter of the cylindrical positioning surface 62 in the sleeve 50 and is inserted into the sleeve 50 from the end 58. When the insert 90 assumes its correct axial position within the sleeve 50, it is released and allowed to expand against the positioning surface 62 of the sleeve 50. The exposed adhesive on the tapes 94 adheres to the positioning surface 62, and the tapes 94 return the insert 92 within the sleeve 50. This prevents the insert 90 from being dislodged when the ring 12 or 14 is installed over the journal 2. Moreover, the tapes 94 prevent the insert 90 from separating from the positioning surface 62 on each side of the gap 92.

Since the journal 2 undergoes little, if any, flexure at the back face 40 of the outboard cone 24, the outboard wear ring may be conventional.

The bearing assembly B with its improved wear rings 12 and 14 has utility in equipment other than railroad axles. For example, the bearing assembly B may be used for the axles of cranes or for the rolls on mill tables.

Claims

Claims:

1. A wear ring comprising: a metal sleeve having an axis and a generally cylindrical sealing surface located around and presented away from the axis, and a generally cylindrical positioning surface that runs out to one end of the sleeve and is presented inwardly toward the axis, the sleeve also having a rib which projects radially inwardly from the cylindrical positioning surface at the other end of the sleeve; and a polymer insert located along and against the cylindrical positioning surface of the sleeve and having a cylindrical interior surface presented toward the axis.

2. A wear ring according to claim 1 wherein the insert extends in excess of one-half the length of the cylindrical positioning surface on the sleeve.

3. A wear ring according to claim 1 wherein the insert terminates short of the end of the sleeve out of which the cylindrical positioning surface of the sleeve opens, so that at that end of the wear ring the sleeve projects beyond the insert.

4. A wear ring according to claim 1 wherein the sleeve is formed from steel.

5. A wear ring according to claim 1 wherein the cylindrical sealing surface of the sleeve runs out to the end of the sleeve out of which the cylindrical positioning surface opens.

6. A wear ring according to claim 1 wherein the rib on the sleeve has a rib bore, and the diameter of the cylindrical positioning surface on the insert is less than the diameter of the rib bore.

7. A wear ring according to claim 1 wherein the polymer of the insert is high density polyethylene.

8. A wear ring according to claim 1 wherein the insert has axially directed edges which are spaced apart to form a gap in the insert

9. A wear ring according to claim 8 and further compressing an adhesive adhering the insert to the positioning surface of the sleeve adjacent to the axially directed edges that form the gap.

10. A bearing assembly for facilitating rotation about an axis, said bearing assembly comprising: a bearing having an inner race provided with at least one raceway that is presented outwardly away from the axis, an outer race having at least one raceway that is presented inwardly toward the axis and toward the raceway on the inner race, and rolling elements arranged in a circular row between the raceways and contacting the raceways; a seal having a case that is fitted to the outer race and an elastomeric seal element attached to the case and located beyond one end of the inner race; and a seal wear ring located at said one end of the inner race and within the seal; the wear ring including a steel sleeve and an insert located within the sleeve, the sleeve having a cylindrical sealing surface which the elastomeric seal element of the seal surrounds and contacts and also an inwardly directed rib located adjacent to said one end of the inner race and containing a bore, the sleeve also having a cylindrical positioning surface which is presented inwardly toward the axis and runs out to the end of the sleeve that is remote from said one end of the inner race, the diameter of the positioning surface being greater than diameter of the bore in the rib, the insert being located along and against the cylindrical positioning surface of the sleeve and having an inner surface that is presented inwardly toward the axis.

11. A bearing assembly according to claim 10 wherein the insert is formed from a polymer.

12 A bearing according to claim 10 herein length of the insert is less than the length of the cylindrical positioning surface on the sleeve.

13. A bearing according to claim 12 wherein the sleeve at its end remote from the inner race projects beyond the insert.

14. A bearing according to claim 10 wherein the inner surface of the insert is cylindrical and has a diameter less than the diameter of the bore in the rib.

15. In combination with a journal that rotates about an axis; a bearing located around the axis and including an inner race fitted tightly to the journal and including an inboard end and an outboard end, an outer race located around the inner race and having an inboard end and an outboard end, and rolling elements located in at least one circular row between the races; and an inboard seal located attached to the outer race of the bearing and having an elastomeric seal element which surrounds the journal; the improvement comprising: an inboard wear ring located around the journal and within the inboard seal; the wear ring including a metal sleeve and a polymer insert located within the sleeve, the sleeve having a cylindrical sealing surface that is presented away from the axis in contact with the elastomeric seal element of the inboard seal and a cylindrical positioning surface that is presented inwardly toward the axis and extends out to the end of the sleeve that is remote from the inner race, the sleeve also having a rib located adjacent to the inboard end of the inner race and projecting radially inwardly past the cylindrical positioning surface, the insert being compressed between the cylindrical positioning surface of the sleeve and the journal.

16. The combination according to claim 15 wherein the journal has a fillet, and further comprising: a backing ring located against the fillet and having an end bore which opens toward the bearing and receives that end of the sleeve on the wear ring that is remote from the inboard end of the bearing.

17. The combination according to claim 15 wherein the insert in the sleeve of the inboard wear ring does not extend into the bore of the backing ring.

18. The combination according to claim 15 wherein the insert is formed from a polymer.

19. The combination according to claim 15 wherein the insert has axially directed edges which are spaced apart to form a gap in the insert.

20. A wear ring according to claim 19 and further comprising an adhesive adhering the insert to the positioning surface of the sleeve adjacent to the axially directed edges that form the gap.