Seal Ring With Auxiliary Ring for Earth-Boring Bit

Abstract

An elastomeric seal ring is located between each bearing pin and each cone of an earth-boring bit. An auxiliary ring or band is imbedded within an annular recess formed in the inner diameter of the seal ring. A portion of the inner diameter of the seal ring as well as the auxiliary ring are in dynamic contact with the bearing pin. The auxiliary ring has a geometric feature that enhances radial flexibility but prevents it from sealing. The geometric feature may be a transverse cut, notches in either the inner or outer diameters, or holes extending between the sides of the auxiliary ring. The auxiliary ring has lubricating properties.

Description

FIELD OF THE INVENTION

This invention relates in general to elastomeric seals for earth boring roller cone bits, and in particular to a seal ring having an annular recess containing an auxiliary ring of a different material.

BACKGROUND OF THE INVENTION

One type of earth-boring bit has a body with at least one rotatable cone mounted to a depending bearing pin. Typically there are three cones, each having rows of cutting elements. The cutting elements may be machined from the metal of the cone, or they may comprise tungsten carbide inserts pressed into holes in the exterior of the cone.

The cone has a cavity that inserts over the bearing pin, forming a journal bearing. The clearances between the bearing surfaces are filled with a grease or lubricant. A seal assembly seals between the bearing pin and the cone near the mouth of the cone.

The seal assembly serves to prevent loss of lubricant to the exterior. Also, the seal assembly serves to exclude debris and cuttings of the borehole from entering the journal bearing. Typically the outer diameter of the seal assembly rotates with the cone and the inner diameter seals against the bearing pin in dynamic contact.

Many different seal assemblies have been proposed and used in the prior art. A variety of shapes of elastomeric seals have been employed. Elastomeric seals that have different materials on the inner and outer diameters are known. Elastomeric seals with carbon fiber fabric on the dynamic portions of the seal are also known. In addition, metal face seal assemblies including an elastomer that urges the metal faces together are also known.

SUMMARY OF THE INVENTION

The seal assembly of this invention comprises a seal ring of an elastomeric material. The seal ring has an inner portion that seals against a sealing surface on the bearing pin and an outer portion that seals against a sealing surface in the cone. At least one auxiliary ring is mounted in a annular recess formed in one of the portions of the seal ring and has a face urged by the seal ring into contact with the sealing surface of the bearing pin or the cone. The auxiliary ring is of a material that differs from the seal ring. In one embodiment, the auxiliary ring is located on the inner portion of the seal ring and provides lubrication to the seal surface on the bearing pin.

In the preferred embodiment, the auxiliary ring does not form a seal against the bearing pin or the cone. It has a geometrical feature that enhances the radial flexibility of the auxiliary ring during installation of the cone on the bearing pin. The geometrical feature is preferably a discontinuity or a pathway one side to the other of the auxiliary ring. The pathway increases flexibility of the auxiliary ring but also prevents it from serving as a seal. In one embodiment, the geometrical feature comprises a transverse cut that severs the auxiliary ring. In another embodiment, notches are formed in the inner or outer diameters. In a third embodiment, holes extend through the width of the auxiliary ring from its interior side to its exterior side.

The seal ring may have more than one auxiliary ring. One of the auxiliary rings may be formed of a self-lubricating material for providing lubrication to the seal ring. Optionally, an auxiliary ring may be located on the outer diameter of the seal ring for frictionally engaging the cone to resist rotation of the seal ring relative to the cone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of an earth-boring bit constructed in accordance with this invention.

FIG. 2 is an enlarged sectional view of one of the cones and bearing pins of the earth-boring bit of FIG. 1, illustrating a seal ring having imbedded auxiliary rings in accordance with the invention.

FIG. 3 is a further enlarged sectional view of a portion of the seal ring and auxiliary rings of FIG. 2.

FIG. 4 is a schematic sectional view of an inner diameter portion of one of the auxiliary rings imbedded within the seal ring of FIG. 2, illustrating a grooved pattern.

FIG. 5 is a partial sectional view of another embodiment of a seal ring and auxiliary ring.

FIG. 6 is a partial sectional view of another embodiment of a seal ring and auxiliary ring.

FIG. 7 is a partial sectional view of another embodiment of a seal ring and auxiliary ring.

FIG. 8 is a partial sectional view of another embodiment of a seal ring and auxiliary ring.

FIG. 9 is a front view of another embodiment of an auxiliary ring in accordance with the invention.

FIG. 10 is a side elevational view of the auxiliary ring of FIG. 9.

FIG. 11 is an enlarged sectional view of a seal ring having an auxiliary ring of FIG. 9 installed therein.

FIG. 12 is a partial front view of another embodiment of an auxiliary ring.

FIG. 13 is a transverse cross-sectional view of still another embodiment of an auxiliary ring.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, bit 11 has a body 13 with a threaded upper end for connection to a drill string for rotation about an axis of body 13. Body 13 has at least one and preferably three bit legs 15. A bearing pin 17 (FIG. 2) depends downward and inward from each bit leg 15.

A cone 19 mounts rotatably to each bearing pin 17. Each cone 19 has a plurality of rows of cutting elements 21. In the example shown, cutting elements 21 comprise tungsten carbide inserts pressed into mating holes drilled in the metal of each cone 19. Alternatively, cutting elements 21 could comprise teeth machined into the metal of each cone 19.

A lubricant compensator 23 supplies lubricant to bearing spaces between the interior of each cone 19 and bearing pin 17. Lubricant compensator 23 also equalizes the pressure of the lubricant with the exterior pressure in the borehole.

Referring to FIG. 2, bearing pin 17 has a cylindrical journal surface 25 that serves as a bearing for the weight imposed on drill bit 11 (FIG. 1). A last machined surface 27 encircles bearing pin 17 on the inside of each bit leg 15. Cone 19 has a cavity 29 with interior surfaces that mate with the exterior surfaces of bearing pin 17. Cone 19 and bearing pin 17 have means for locking cone 19 on bearing pin 17. In this embodiment, the locking means comprises a plurality of balls 31 located within mating grooves formed on bearing pin 17 and in cone cavity 29.

A seal groove 33 is formed in cavity 29 near its mouth. In this embodiment, groove 33 is rectangular when viewed in cross-section. Groove 33 has a flat base or outer diameter 33a, when viewed in transverse cross-section, and two flat sidewalls 33b.

A seal ring 35 is carried within groove 33 for sealing lubricant against leakage to the exterior. Seal ring 35 is formed of an elastomeric material of a type that is conventional for elastomeric seals for earth-boring bits. Preferably this material comprises a nitrile rubber such as hydrogenated nitrile butadiene rubber, but it could be other types of material as well. Seal ring 35 has an outer portion or diameter 37 that seals against groove 33. Seal ring 35 has an inner diameter or portion 41 that may appear flat when viewed in the transverse cross-section of FIG. 2. Inner diameter 41 seals and normally rotatably slides against bearing pin journal surface 25. Seal ring 35 has an exterior side 42a and an interior side 42b, which are shown in parallel planes, but could be other shapes. Side 42a is on the exterior side of seal ring 35 and is exposed to drilling fluid during operation through the clearance between last machined surface 27 and the backface of cone 19. Side 42b is on the interior side of seal ring 35 and is in contact with lubricant contained in the bearing spaces. Sidewalls 42a, 42b are spaced slightly from groove sidewalls 33b so as to accommodate deformation.

At least one thermoplastic auxiliary band or ring 43 is located within seal ring 35. Three auxiliary rings 43 are shown in this embodiment, but the number could be less or more. Referring to FIG. 3, in this embodiment, each auxiliary ring 43 is located within an annular recess or annular recess 45 formed in seal ring inner diameter 41. Auxiliary rings 43 may be bonded within annular recesses 45 or held by friction. Each auxiliary ring 43 has a contacting face 47 on its inner diameter that is urged by seal ring 35 into dynamic contact with bearing pin journal surface 25.

In this example, auxiliary rings 43 are spaced apart from each other along the axis of bearing pin 17. The spacing results in annular sections 49 of seal ring 35 located on each lateral side of each auxiliary ring 43, each section 49 sealing against bearing pin journal surface 25. One of the sections 49 is located between exterior side 42a and its closest auxiliary ring 43 and another between interior side 42b and its closest auxiliary ring 43. Also, a section 49 exists between each of the auxiliary rings 43. The width of seal ring 35 from interior side 42b to exterior side 42a is greater than the total combined width of the contacting face 47 of each auxiliary ring 43.

In FIG. 2, auxiliary rings 43 are shown with a rectangular configuration when viewed in transverse cross-section, each having a cylindrical contact face 47 and a cylindrical outer diameter. However, other cross-sectional configurations are feasible. In FIG. 3, auxiliary rings 43 are shown with a circular configuration.

Auxiliary rings 43 also slidingly engage journal surface 25, but do not form a sealing engagement with journal surface 25 because they serve other purposes. Auxiliary rings 43 may be formed of a material containing a lubricant additive for providing lubrication to journal surface 25. In the preferred embodiment, auxiliary rings 43 are formed of one of the following materials: polytetrafluoroethylene (“PTFE”), polyaryletheretherketone or polyether ether ketone (“PEEK”), polyphenylenesulfide and fiber reinforced composites thereof. For lubrication, the material may contain more than 20% by volume lubricant additive. PTFE is a material that lubricates, but PEEK is not self-lubricating. As example, the material of auxiliary rings 43 could consist essentially of the following: 100% virgin PTFE; PTFE with the balance being a filler up to about 25% of carbon graphite, glass fibers, or metallic particles; or PEEK with a filler of PTFE of 15% or more. However, other materials are also feasible. The material should be resistant to relative high temperatures and resistant to abrasion due to cuttings and other erosive particles in the drilling fluid. Typically the material of auxiliary rings 43 is not as flexible as the material of seal ring 35.

The lubricant additive of auxiliary ring 43 flows or is imparted to journal surface 25 so as to lubricate the portions of journal surface 25 dynamically engaged by seal ring 35. Material thus is intended to be dispersed or worn away from faces 47 of auxiliary rings 43. Auxiliary rings 43 intended for lubrication thus have a less wear resistance than seal ring 35. Alternately, auxiliary rings 43 could be intended to exclude debris, and in that instance may or may not have lubricant additives.

Micro texturing may be formed in the inner diameters 47 of each auxiliary ring 43. Micro texturing comprises very shallow recesses formed in the surface by known techniques, such as by laser. A wide variety of texturing is feasible. As an example, FIG. 4 shows generally sinusoidal grooves 51 extending in three rows around the inner diameter 47. Grooves 51 tend to retain lubricant on journal surface 25.

In operation, as bit 11 rotates, each cone 19 will rotate about its bearing pin 17 (FIG. 2). Each seal ring 35 will tend to rotate with its cone 19 and sealingly engage journal surface 25 of bearing pin 17 in dynamic sliding contact. Auxiliary rings 43 also engage journal surface 25 in dynamic contact but not sealing contact.

In FIG. 5, a cone 53 is mounted on a roller bearing pin 55, generally as in the first embodiment. Seal ring 57 has an inner portion that seals in rotating dynamic contact with bearing pin journal surface 59 and an outer portion that seals against cone cavity 61. In this embodiment, a single auxiliary ring 63 is mounted in an annular recess on the inner portion of seal ring 57. Auxiliary ring 63 has a generally flat face that contacts but does not seal against journal surface 59. The remaining cross-sectional shape of auxiliary ring 63 is curved and convex. Portions of the inner portion of seal ring 57 on the interior and exterior sides of auxiliary ring 63 sealingly engage journal surface 59.

In FIG. 6, a cone 65 is mounted on a bearing pin 67 generally as in the first embodiment. Seal ring 69 has an inner portion that seals in rotating dynamic contact with bearing pin journal surface 71 and an outer portion that seals against cone cavity 73. In this example, there are two auxiliary rings 75, 77, and each has a contacting face with a different configuration. Auxiliary ring 75 is located on the exterior side of auxiliary ring 77 and has a convex or rounded cross-sectional shape, including its contacting face. Auxiliary ring 77 may be formed of a material that provides lubrication and may be softer than auxiliary ring 75 and seal ring 69.

In FIG. 7, a cone 79 is mounted on a bearing pin 81 generally as in the first embodiment. Seal ring 83 has an inner portion that seals in rotating dynamic contact with bearing pin journal surface 85 and an outer portion that seals against a groove 87 in cone 79. Groove 87 is triangular shaped in this example. Seal ring 83 has a flat exterior side 89a and a flat interior side 89b that wedge against the sides of annular recess 87. A single auxiliary ring 91 in shown on the inner portion of seal ring 83 in engagement with journal bearing surface 85, but more than one is feasible. Auxiliary ring 91 may be of various shapes and is shown to have a shape generally like that of auxiliary ring 63 in FIG. 5.

In FIG. 8, a cone 93 is mounted on a bearing pin 95 generally as in the first embodiment. Seal ring 97 has an inner portion that seals in rotating dynamic contact with bearing pin journal surface 99 and an outer portion that seals against a groove 101 in cone 93. Two auxiliary rings 103 are shown on the inner diameter of seal ring 97. Auxiliary rings 103 are shown with shapes similar to that of auxiliary ring 63 in FIG. 5.

An outer auxiliary ring 105 is shown embedded within an annular recess on the outer diameter of seal ring 97 and in frictional engagement with the base of cone groove 101. Outer auxiliary ring 105 serves to frictionally grip cone 93 to resist slippage and rotation of seal ring 97 relative to cone 93. Outer auxiliary ring 105 may be formed of a material that has good gripping properties, the hardness of which may be less than seal ring 97. Outer auxiliary ring 105 may have a variety of shapes, but is shown as having a shape similar to auxiliary ring 63 of FIG. 5. Although not expected, it is possible that one prefers to cause seal ring 97 to remain stationary on bearing pin 95 while cone 93 rotates. If so, auxiliary ring 105, having a high surface friction, would be located on the inner diameter of seal ring 97 and one or more auxiliary rings 103 for retarding wear and/or enhancing lubrication would be located on the outer diameter of seal ring 97.

FIGS. 9-12 illustrating auxiliary rings that have more flexibility so as to be rapidly expanded in diameter when the cone is being installed on the bearing pin. Auxiliary ring 107 may be any one of the auxiliary rings 43, 63, 75, 77, 91, 103 or 105 previously discussed. Auxiliary ring 107 has a geometric feature to enhance radial flexibility, which in this embodiment comprises a transverse cut 109 that completely severs it, creating two ends that abut each other. As shown in FIG. 10, cut 109 is preferably a skive cut, extending in a straight line from one side 111 to the other side 113. Cut 109 is formed at an acute angle 115 relative to a plane containing either side 111 or side 113. The angle may vary and is shown to be about 10 degrees. Cut 109 is thus also at an angle relative to the axis 117 of auxiliary ring 107. Cut 109 forms a fluid communication pathway that prevents auxiliary ring 107 from sealing against journal surface 25 of bearing pin 17 (FIG. 2).

Referring to FIG. 11, auxiliary ring 107 is shown installed within an annular recess 119 in the inner diameter 120 of a seal ring 121. Seal ring 121 may be similar to seal rings 35, 57, 69, 83, or 97 previously discussed. In this example, seal ring 121 has a high aspect ratio, which is its radial thickness compared to its axial width. Seal ring 121 may have ribs 123 on each side to stabilize ring 121 within its groove (not shown). Seal ring 121 is shown in a relaxed position before installation in its groove. Prior to installing seal ring 121 in groove 33 of cone 19 (FIG. 2), the face or inner diameter 125 of auxiliary ring 107 is recessed within annular recess 119. Once installed between cone groove 33 and bearing pin journal surface 25(Fig. 2), inner diameter 125 of auxiliary ring 107 will be in contact with bearing pin journal surface 25 and flush with inner diameter 120 of seal ring 121.

Auxiliary ring 107 may be installed in annular recess 119 without attempting to stretch inner diameter 120 of seal ring 121. Instead, auxiliary ring 107 is squeezed or forced radially inward so that its outer diameter 127 is smaller than inner diameter 120 of seal ring 121. While doing so, the ends of auxiliary ring 107 formed by cut 109 will slide past and overlap each other. Once in alignment with annular recess 119, the radial inward force is removed, allowing auxiliary ring 107 to resiliently spring into annular recess 119. Once in annular recess 119, outer diameter 127 of auxiliary ring 107 will be in contact with the inner diameter of annular recess 119 and its inner diameter 125 will be slightly recessed, as shown in FIG. 11.

Normally, after installing auxiliary ring 107 in annular recess 119, seal ring 121 would then be placed in a cone seal groove such as seal groove 33 of cone 19 (FIG. 2). Prior to installing seal ring 121 in seal groove 33, inner diameter 125 is slightly greater than the outer diameter of journal surface 25 (FIG. 2). After installation in groove 33, the outer diameter or base 33a of groove 33 will push the inner diameter 120 of seal ring 121 and the inner diameter 125 of auxiliary ring 107 radially inward to a diameter smaller than the outer diameter of journal surface 25. The smaller inner diameters create an interference, which for example, may be about 0.010 inch on a side.

The installer will supply sufficient force and optionally impacts to force cone 19 over bearing pin 17. Journal surface 25 will force the seal ring and auxiliary ring inner diameters 120 and 125 to rapidly expand outward as cone 19 moves onto bearing pin 17. Unlike seal ring 121, auxiliary ring 107 may be formed of a material that is less elastic and does not quickly expand. Cut 109 allows the rapid radial expansion to occur without any chance of damaging auxiliary ring 107. After installation on bearing pin 17, seal ring 37 will be squeezed against journal surface 25 to a desired amount, typically from 5 to 15%. Inner diameter 125 of auxiliary ring 107 will be in contact with journal surface 25.

Cut 109 will prevent auxiliary ring 107 from sealing against bearing pin journal surface 25 because it forms a fluid communication path. Any pressure differential between its sides 111 would allow fluid to flow past auxiliary ring 107. However, auxiliary ring 107 is not intended to seal as this is done by seal ring 121. Auxiliary ring 107 will not be exposed to a pressure differential from one of its sides 111 to the other as long as seal ring 121 is sealing properly.

There are alternatives to allow the rapid expansion of auxiliary ring 107 rather than forming a cut. For example, FIG. 12 shows an auxiliary ring 129 with one or more notches 131 formed in the inner diameter of auxiliary ring 129. Alternately, notches 131 could be formed in the outer diameter. Notches 131 are spaced apart from each other around the circumference of auxiliary ring 129 and extend from one lateral side to the other. Notches 131 would reduce the radial thickness of auxiliary ring 107 where they occur, making auxiliary ring 129 more flexible. Notches 131 also form fluid communication pathways between the lateral sides of auxiliary ring 129.

FIG. 13 shows a sectional view of an auxiliary ring 133. In this embodiment, at least one and preferably several holes 135 are formed in auxiliary ring 133. Each hole 135 axially extends from an interior side to an exterior side of auxiliary ring 133. Preferably holes 135 are spaced equally around the circumference of auxiliary ring 133. Holes 135 increase the radialy flexibility of auxiliary ring 133 to allow it to rapidly be expanded in diameter. Holes 135 provide fluid communication pathways across auxiliary ring 133, preventing sealing across auxiliary ring 107 to occur.

The term “auxiliary” has been used in connection with the rings, whether designed to exclude and trap debris, or to lubricate, or to resist rotation. This term is used only for convenience and not in a limiting manner.

The invention has significant advantages. Auxiliary rings with lubricating properties may be used to add lubrication, which reduces heat and prolongs the life of the seal ring. Auxiliary rings with gripping properties may be used to resist rotation of the seal ring. Auxiliary rings may also serve to exclude debris.

While the invention has been shown in only a few of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the invention.

Claims

1. An earth boring bit having a body with a depending bearing pin, and a cone rotatably mounted to the bearing pin, the cone having a plurality of cutting elements, the improvement comprising: an elastomeric seal ring having an outer portion in sealing engagement with a seal surface on the cone and an inner portion in sealing engagement with a seal surface on the bearing pin;an annular recess extending around one of the portions of the seal ring;an auxiliary ring carried in the annular recess and having a face urged by the seal ring into contact with one of the sealing surfaces;said one of the portions of the seal ring has sections on opposite lateral sides of the auxiliary ring that sealingly engage said one of the seal surfaces; anda geometric feature in the auxiliary ring that enhances radial flexibility of the auxiliary ring and prevents it from sealing.

2. The bit according to claim 1, wherein the geometric feature comprises a fluid communication path extending from one of the lateral sides to the other of the lateral side of the auxiliary ring.

3. The bit according to claim 1, wherein the geometric feature comprises: a skive cut extends from one of the lateral sides to the other of the lateral sides, completely severing the auxiliary ring; andthe skive cut is formed at an acute angle relative to the lateral sides of the auxiliary ring.

4. The bit according to claim 1, wherein the geometric feature comprises: at least one hole extending through the auxiliary ring from one its lateral sides to the other of its lateral sides.

5. The bit according to claim 1, wherein: the auxiliary ring has an inner diameter and an outer diameter; and the geometric feature comprisesat least one recess on at least one of the diameters that extends from one of its lateral sides to the other of its lateral sides.

6. The bit according to claim 1, wherein: the annular recess is located in the inner portion of the seal ring, and the auxiliary ring is in sliding engagement with the seal surface on the bearing pin; andthe auxiliary ring is formed of a self-lubricating material.

7. The bit according to claim 1, wherein the auxiliary ring is formed of a material that consists essentially of PTFE.

8. The bit according to claim 1, wherein the auxiliary ring is formed of a material consisting essentially of PTFE and a filler material selected from one or more of the following: carbon graphite, glass fibers, and metallic particles.

9. The bit according to claim 1, wherein the auxiliary ring is formed of PEEK with a filler of PTFE.

10. An earth boring bit, comprising: a body having a depending bearing pin;a cone having a cylindrical cavity mounted rotatably on the bearing pin, the cone having an exterior containing a plurality of cutting elements, the cone and the bearing pin defining bearing spaces filled with a lubricant;a seal ring of nitrile rubber, having an outer diameter in sealing contact with the cavity of the cone and an inner diameter in sealing contact with the bearing pin, the seal ring having an exterior side exposed to drilling fluid during operation and an interior side exposed to lubricant within the bearing spaces;an annular recess formed in the inner diameter of the seal ring between the interior and exterior sides;at least one thermoplastic auxiliary ring having an interior side and an exterior side and located in the annular recess, the auxiliary ring having an inner diameter urged by the seal ring into dynamic contact with the bearing pin; andat least one pathway extending from the interior side to the exterior side of the auxiliary ring to increase radial flexibility of the auxiliary ring.

11. The bit according to claim 10, wherein the pathway comprises a cut that severs the auxiliary ring.

12. The bit according to claim 10, wherein the auxiliary ring has an outer diameter in contact with a base of the annular recess, and said at least one pathway comprises a plurality of recesses formed on one of the diameters of the auxiliary ring.

13. The bit according to claim 10, wherein said at least one pathway comprises a plurality of holes in the auxiliary ring, each extending from the interior side to the exterior side.

14. The bit according to claim 10, wherein the inner diameter of the auxiliary ring after the seal ring and auxiliary ring are installed in the groove of the cone and prior to installing the cone on the bearing pin are less than an outer diameter of the bearing pin; andthe pathway allows the auxiliary ring to rapidly expand during installation of the cone on the bearing pin.

15. The bit according to claim 10, wherein the auxiliary ring is formed of a material that consists essentially of PTFE.

16. The bit according to claim 10, wherein the auxiliary ring is formed of a material consisting essentially of PTFE and a filler material selected from one or more of the following: carbon graphite, glass fibers, and metallic particles.

17. The bit according to claim 10, wherein the auxiliary ring is formed of PEEK with a filler of PTFE.

18. An earth boring bit, comprising: a body having a depending bearing pin;a cone having a cylindrical cavity mounted rotatably on the bearing pin, the cone having an exterior containing a plurality of cutting elements;an annular groove in the cylindrical cavity of the cone;a seal ring of elastomeric material and having an outer portion in sealing contact with the groove and an inner portion;an annular recess extending around the inner portion of the seal ring, defining segments of the seal ring on each side of the recess that are in dynamic sealing contact with the bearing pin;an auxiliary ring within the annular recess of the seal ring, the auxiliary ring having an outer diameter in contact with a base of the annular recess and an inner diameter in contact with the bearing pin, the auxiliary ring having an interior side and an exterior side;the inner diameter of the auxiliary ring after the seal ring and auxiliary ring are installed in the groove of the cone and prior to installing the cone on the bearing pin being less than an outer diameter of the bearing pin; anda cut extending from the interior side to the exterior side of the auxiliary ring,, severing and providing radial flexibility to the auxiliary ring to allow the auxiliary ring to rapidly expand during installation of the cone on the bearing pin.

19. The bit according to claim 18, wherein prior to installation of the auxiliary ring and the seal ring in the annular recess in the cone, the inner diameter of the auxiliary ring is greater than the outer diameter of the bearing pin.

20. The bit according to claim 18, wherein the auxiliary ring is formed of a material that has less elasticity than the seal ring.