US20080041635A1

US20080041635A1 - Seal for an earth bit

Info

Publication number: US20080041635A1
Application number: US11/840,959
Authority: US
Inventors: Gregory W. Peterson
Original assignee: Atlas Copco Secoroc LLC
Current assignee: Epiroc Drilling Tools LLC
Priority date: 2006-08-18
Filing date: 2007-08-18
Publication date: 2008-02-21

Abstract

An earth bit includes a cutting cone rotatably mounted to a lug with a hub unit. A sealing member is positioned to provide a seal between the cutting cone and lug. The sealing member includes an O-ring core enclosed by a sleeve having a seam extending annularly around it. The seam restricts the rotation of the sleeve around the O-ring core.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional Application No. 60/822,891 filed in Aug. 18, 2006, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates generally to earthboring tools for boring a hole.
2. Description of the Related Art
Earthboring tools are commonly used to bore holes by cutting through earthen annulus. Such holes may be bored for many different reasons, such as drilling for oil, minerals and water. One type of earthboring tool used for boring is a rotary earth bit, with several examples being disclosed in U.S. Pat. Nos. 3,550,972, 3,847,235, 4,136,748, 4,427,307, 4,688,651 and 4,741,471. A rotary earth bit generally includes an earth bit body which carries one or more lugs. A cutting cone is rotatably mounted to each lug with a hub unit, as well as ball bearings. As the earth bit body rotates, the lugs rotate and the cutting cones rotate about the hub unit and ball bearings in response to contacting earthen annulus.
It is known that earthboring tools generally include one or more seals for retaining a lubricant between the hub unit and cutting cone to reduce the amount of friction between them. However, as discussed in U.S. Pat. No. 5,842,700, a seal is more likely to fail if it is exposed to high temperature, pressure and/or abrasive environments. Replacing an earth bit, or a component thereof, is costly and time consuming, so it is desirable to decrease the amount of wear it experiences.

BRIEF SUMMARY OF THE INVENTION

The present invention employs a sealing member for use with an earth bit, wherein the earth bit includes a cutting cone rotatably mounted to a lug with a hub unit. The sealing member is positioned to retain lubricant between the cutting cone and lug. The sealing member includes an O-ring core enclosed by a sleeve having a seam extending around it. The sleeve includes a wear resistant material and the seam extends away from the O-ring core so it engages a static sealing surface. The seam engages the static sealing surface to restrict the rotation of the sleeve about the O-ring core. In some embodiments, the static sealing surface is a surface of the cutting cone and, in other embodiments, the static sealing surface is a surface of the hub unit. If desired, the sealing member can include two seams, wherein both seams engage static sealing surfaces.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings and description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an earth bit having a sealing member, in accordance with the invention.

FIG. 2 is a close-up side view of the earth bit of FIG. 1 showing the sealing member.

FIG. 3 a is a top view of the sealing member of FIG. 2.

FIGS. 3 b and 3 c are cut-away views of the sealing member of FIG. 3 a taken along a cut-line 4-4, wherein the sealing member includes one and two seams, respectively.

FIGS. 3 d, 3 e and 3 f are cut-away views of the sealing member of FIG. 3 a taken along a cut-line 4-4, wherein the sealing member includes more than one seam.

FIG. 4 a is a top view of a sleeve which includes a single sleeve piece.

FIG. 4 b is a cut-away side view of the sleeve of FIG. 4 a enclosing an O-ring core taken along a cut-line 4-4, in accordance with the invention.

FIG. 4 c is a perspective view, along cut-line 4-4, of the sleeve of FIG. 4 a enclosing the O-ring core of FIG. 4 b, wherein the sleeve has one seam.

FIG. 5 a is a top view of a sleeve which includes two sleeve pieces.

FIG. 5 b is a side view of the sleeve of FIG. 5 a enclosing the O-ring core taken along cut-line 4-4, in accordance with the invention.

FIG. 5 c is a perspective view, along cut-line 4-4, of the sleeve of FIG. 5 a enclosing the O-ring core of FIG. 5 b, wherein the sleeve has two seams.

FIGS. 6 and 7 are flow diagrams of methods of assembling an earth bit, in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of an earth bit 100, in accordance with the invention, and FIG. 2 is a cut-away side view of earth bit 100 taken along a cut-line 2-2 of FIG. 1. Earth bit 100 includes several earth bit components assembled together. In this embodiment, these components include an earth bit body 101 which carries lugs 102 coupled to corresponding cutting cones 103. In this particular embodiment, earth bit 100 includes three cutting cones and corresponding lugs, so that earth bit 100 is a tri-cone earth bit. Cutting cones 103 are rotatably mounted to corresponding lugs 102 with a hub unit 104, as well as ball bearings 106. In operation, as earth bit body 101 rotates, lugs 102 rotate, and cutting cones 103 rotate about hub unit 104 and ball bearings 106 in response to contacting earthen annulus. It should be noted that cutting cone 103 rotates about an axis of rotation 135, as shown in FIG. 2.
In accordance with the invention, earth bit 100 includes a sealing member 105 (FIG. 2) positioned so it forms a seal between hub unit 104 and cutting cone 103. In this embodiment, sealing member 105 is positioned within an annular groove 107 which extends through cutting cone 103 so it faces hub unit 104. Annular groove 107 includes radial surface 130 with opposed axial surfaces 132 and 133.
In this embodiment, sealing member 105 forms a static seal with radial surface 130, as well as axial surfaces 132 and 133. Further, sealing member 105 forms a dynamic seal with a radial surface 131 of hub unit 104. It should be noted that an axial surface extends perpendicular to axis 135 and a radial surface extends parallel to axis 135. Further, it should be noted that a static seal is formed between surfaces that engage each other, but do not rotate relative to each other. A dynamic seal is formed between surfaces that engage each other and rotate relative to each other.
Hence, in this embodiment, sealing member 105 engages cutting cone 103 and hub unit 104 so that there is a static seal between sealing member 105 and cutting cone 103 and a dynamic seal between sealing member 105 and hub unit 104. It should be noted that, in some embodiments, sealing member 105 is positioned to form a seal between cutting cone 103 and lug 102. Sealing member 105 can also be positioned to from a seal between cutting cone 104 and both lug 102 and hub unit 104.
In operation, sealing member 105 rotates in response to the rotation of cutting cone 103 relative to hub unit 104. Sealing member 105 retains lubricant between cutting cone 103 and hub unit 104 so that the lubricant reduces the amount of friction between them. Sealing member 105 also forms a seal so that abrasive material is restricted from flowing to a position between cutting cone 103 and hub unit 104. Abrasive material positioned between cutting cone 103 and hub unit 104 can undesirably increase the friction between them. The abrasive material can be of many different types, such as earthen annulus. As discussed in more detail below, sealing member 105 allows cutting cone 103 to rotate about hub unit 104 when the amount of lubricant therebetween is low.
FIG. 3 a is a top view of sealing member 105, in accordance with the invention. In this embodiment, sealing member 105 includes an O-ring core 110 enclosed by a sleeve 111, wherein O-ring core 110 is toroidal in shape and sleeve 111 extends around it. In accordance with the invention, sleeve 111 is slidingly engaged with O-ring core 110. It should be noted that O-ring core 110 can have many other shapes, such as rectangular, X-shaped, L-shaped, but a toroidal shape is shown here for illustrative purposes. O-ring core 110 can include many different types of materials, but it generally includes an elastomeric material, such as rubber or plastic.
Sleeve 111 can include many different types of materials, but it generally includes a wear resistant material, such as a polymer. The wear resistant material included with sleeve 111 can also include natural or composite fibers that are braided, woven or non-woven. In general, the material included with sleeve 111 is chosen to be stronger and more resistant to abrasion and friction than the material included with O-ring core 110.
The material included with sleeve 111 is chosen to be more resistant to friction so that sealing member 105 has less friction with hub unit 104. For example, the friction between sleeve 111 and hub unit 104 is chosen so that sealing member 105 has less friction between it and hub unit 104 when it includes sleeve 111 than when it does not. In this way, sleeve 111 operates as a lubricating member between cutting cone 103 and hub unit 104 so that cutting cone 103 can rotate about hub unit 104 when the lubricant between them is low.
It should be noted that the friction between sleeve 111 and hub unit 104 can be decreased in many different ways. For example, the portion of sleeve 111 that engages hub unit 104 can be smoothed to decrease its surface roughness. In another example, the portion of sleeve 111 that engages hub unit 104 can be lubricated. The portion of sleeve 111 that faces cutting cone 103 can be made rough so that there is more friction therebetween. In this way, sealing member 105 is more likely to rotate with cutting cone 103 so there is less slippage between them. There is less slippage between sealing member 105 and cutting cone 103 when they rotate less relative to each other.
It should also be noted that, in general, sleeve 111 includes one or more sleeve pieces which are connected together with one or more seams. The seam(s) extend outwardly from O-ring core 110 and annularly around it. The seam(s) can be positioned at many different locations relative to O-ring core 110, but it is generally desirable for the seam(s) to engage a static sealing surface, several of which were discussed in more detail above.
For example, sleeve 111 includes seam(s) (FIG. 3 f) positioned proximate to inner and/or outer portions 112 a and 112 b of O-ring core 110. The seams are positioned proximate to inner and outer portions 112 a and 112 b when O-ring core 110 is being used in an axial sealing application.
In another example, sleeve 111 includes seam(s) (not shown) positioned between inner and outer portions 112 a and 112 b of O-ring core 110. For example, the seams can be positioned proximate to upper and lower portions 113 a and 113 b (FIG. 5 c) of O-ring core 110. Seam(s) are positioned between inner and outer portions 112 a and 112 b when O-ring core 110 is being used in a radial sealing application. More information regarding radial and axial sealing applications can be found in U.S. Pat. No. 6,026,917.
FIG. 3 b is a cut-away view of a sealing member 105 a taken along a cut-line 3-3 of FIG. 3 a. It should be noted that sealing member 105 a corresponds to one embodiment of sealing member 105 wherein sealing member 105 includes a single sleeve piece 111 a which extends around O-ring core 110. In accordance with the invention, sealing member 105 a includes a seam 116 which extends annularly along outer portion 112 a of O-ring core 110. In this embodiment, seam 116 is positioned to face towards cutting cone 103 and away from hub unit 104 when sealing member 105 a is positioned in annular groove 107 (FIG. 2). In this way, seam 116 is statically engaged with radial surface 130 and inner portion 112 b is dynamically engaged with radial surface 131 of hub unit 104. It should be noted that sealing member 105 a is used in a radial sealing application, such as that shown in FIG. 2, wherein seam 116 statically engages a radial sealing surface.
The engagement of seam 116 with cutting cone 103 allows sealing member 105 a to provide a better seal therebetween. As discussed above, a better seal prevents lubricant and abrasive material from flowing therethrough. Further, the engagement of seam 116 with cutting cone 103 restricts the rotation of sleeve 111 about O-ring core 110. This is useful because the rotation of sleeve 111 about O-ring core 110 can cause sleeve 111 to twist relative to O-ring core 110. The twisting of sleeve 111 can cause it to crease, which can decrease its sealing ability. The sealing ability of sealing member 105 a is decreased when it allows more lubricant and abrasive material to flow therethrough.
FIG. 3 c is a cut-away view of a sealing member 105 b taken along cut-line 3-3 of FIG. 3 a. It should be noted that sealing member 105 b corresponds to one embodiment of sealing member 105 wherein sealing member 105 includes sleeve pieces 111 a and 111 b which extend around O-ring core 110. In accordance with the invention, sealing member 105 b includes seams 115 and 116 which extend annularly along outer and upper portions 112 a and 113 a, respectively, of O-ring core 110 so they face cutting cone 103. In this way, seams 115 and 116 are unopposed to each other. In this embodiment, seam 115 engages radial surface 130 and seam 116 can engage axial surface 132 or 133 (FIG. 2), depending on the orientation of sealing member 105 b in annular groove 107. The engagement of seams 115 and 116 with cutting cone 103 restricts the rotation of sleeve 111 about O-ring core 110.
It should be noted that sealing member 105 b is used in a radial sealing application wherein seams 115 and 116 statically engage radial sealing surfaces. Further, a seam can be positioned proximate to lower portion 113 b of O-ring core 110, as will be discussed in more detail presently.
FIG. 3 d is a cut-away view of a sealing member 105 c taken along cut-line 3-3 of FIG. 3 a. It should be noted that sealing member 105 c corresponds to one embodiment of sealing member 105 wherein sealing member 105 includes sleeve pieces 111 a, 111 b and 111 c which extend around O-ring core 110. In accordance with the invention, sealing member 105 c includes seams 115, 116 and 117 which extend annularly along outer, upper and lower portions 112 a, 113 a and 113 b, respectively, of O-ring core 110 so they face cutting cone 103. Sleeve piece 111 a extends between seams 115 and 117, sleeve piece 111 b extends between seams 115 and 116 and sleeve piece 111 c extends between seams 116 and 117.
In this embodiment, seam 115 engages radial surface 130, seam 116 engages axial surface 132 and seam 117 engages axial surface 133 (FIG. 2). It should be noted that, if desired, sealing member 105 c can be oriented in annular groove 107 so that seams 116 and 117 engage axial surfaces 133 and 132, respectively. The engagement of seams 115, 116 and 117 with cutting cone 103 restricts the rotation of sleeve 111 about O-ring core 110.
FIG. 3 e is a cut-away view of a sealing member 105 d taken along cut-line 3-3 of FIG. 3 a. It should be noted that sealing member 105 d corresponds to one embodiment of sealing member 105 wherein sealing member 105 includes sleeve pieces 111 a and 111 b which extend around O-ring core 110. In accordance with the invention, sealing member 105 d includes seams 115 and 117 which extend annularly along upper and lower portions 113 a and 113 b, respectively, of O-ring core 110 so they face cutting cone 103. In this way, seams 115 and 117 are opposed to each other.
In this embodiment, seam 115 engages axial surface 132 and seam 117 engages axial surface 133 (FIG. 2). It should be noted that, if desired, sealing member 105 d can be oriented in annular groove 107 so that seams 115 and 117 engage axial surfaces 133 and 132, respectively. The engagement of seams 115 and 117 with cutting cone 103 restricts the rotation of sleeve 111 about O-ring core 110.
FIG. 3 f is a cut-away view of a sealing member 105 e taken along cut-line 3-3 of FIG. 3 a. It should be noted that sealing member 105 e corresponds to one embodiment of sealing member 105 wherein sealing member 105 includes sleeve pieces 111 a and 111 b which extend around O-ring core 110. In accordance with the invention, sealing member 105 e includes seams 115 and 116 which extend annularly along outer and inner portions 112 a and 112 b, respectively, of O-ring core 110. Sealing member 105 e is used in an axial sealing application (not shown) wherein seams 115 and 116 statically engage axial sealing surfaces.
It should be noted that seams 115, 116 and 117 can be formed in many different ways, such as by stitching sleeve pieces 111 a, 111 b and 111 c together. Seams 115, 116 and 117 can also be formed by using an adhesive or thermal bonding. It should also be noted that, in some embodiments, portions of sleeve pieces 111 a, 111 b and 111 c proximate to seams 115, 116 and 117 can overlap.
FIG. 4 a is a top view of sleeve 111 of FIG. 3 b, wherein sleeve 111 includes sleeve piece 111 a. In this embodiment, sleeve 111 includes opposed sides 120 and 121, as well as opposed sides 122 and 123. It should be noted that the shape of sleeve 111, as well as the dimensions of sides 120, 121, 122 and 123 are chosen so that sleeve 111 wraps around O-ring core 110. It is useful if sleeve 111 wraps around O-ring core 110 without any undesirable separation therebetween to reduce the likelihood of sleeve 111 having a crease.
FIGS. 4 b and 4 c are cut-away end and perspective views, respectively, of sealing member 105 wherein sealing member 105 corresponds to sealing member 105 a of FIG. 3 b with seam 116 extending annularly along outer portion 112 a of O-ring core 110. The views of FIGS. 4 b and 4 c are taken along cut-line 4-4 of FIG. 3 a. In this embodiment, sleeve piece 111 a is wrapped around O-ring core 110 and opposed sides 120 and 121 are coupled together by seaming to form seam 116. By seaming together opposed sides 120 and 121, sleeve piece 111 a can be wrapped around O-ring core 110 without attaching it thereto, such as with adhesives or bonding. In this way, sleeve piece 111 a is slidingly engaged with the O-ring core 110 instead of fixedly attached thereto. Sleeve piece 111 a is slidingly engaged with O-ring core 110 so that they can be rotated relative to each other. Slidingly engaging sleeve piece 111 a with O-ring core 110 is useful so that they are repeatably moveable between positions engaged with and disengaged from each other.
In this embodiment, sides 122 and 123 are coupled together by seaming to form a seam 114, wherein seam 114 extends between inner and outer portions 112 and 113 of O-ring core 110 (FIG. 3 a). Seam 114 is formed so that sleeve 111 encloses O-ring core 110 and decreases the amount of wear it experiences. In this way, O-ring core 110 does not need to be replaced as often, which reduces the operating cost and downtime of earth bit 100. It should be noted that seam 114 generally extends at a non-zero angle relative to seams 115 and 116. In this particular example, seam 114 extends perpendicular to seams 115 and 116. In this way, seam 114 does not extend annularly around O-ring core 110.
FIG. 5 a is a top view of sleeve 111 of FIG. 3 e, wherein sleeve 111 includes sleeve pieces 111 a and 111 b coupled together. In this embodiment, sides 120 and 121 extend along sleeve pieces 111 a and 111 b, respectively, and seam 117 extends between sleeve pieces 111 a and 111 b. Seam 117 couples together sleeve pieces 111 a and 111 b and extends annularly along lower portion 113 b of O-ring core 110, as discussed above with FIG. 3 e.
FIGS. 5 b and 5 c are cut-away end and perspective views, respectively, of sleeve member 105 wherein sleeve member 105 corresponds to sleeve member 105 d of FIG. 3 e with seams 115 and 117 extending annularly along upper and lower portions 113 a and 113 b, respectively, of O-ring core 110. In this way, seams 115 and 117 oppose each other. The views of FIGS. 5 b and 5 c are taken along cut-line 4-4 of FIG. 3 a.
In this embodiment, sleeve pieces 111 a and 111 b are wrapped around O-ring core 110 and opposed sides 120 and 121 are coupled together by seaming to form seam 115. In this way, sleeve pieces 111 a and 111 b are coupled together by seams 115 and 117. By seaming together opposed sides 120 and 121, sleeve pieces 111 a and 111 a can be wrapped around O-ring core 110 without attaching them thereto, such as with adhesives or bonding. In this way, sleeve pieces 111 a and 111 b are slidingly engaged with O-ring core 110 instead of fixedly attached thereto. Sleeve pieces 111 a and 111 b are slidingly engaged with O-ring core 110 so that pieces 111 a and 111 b can be rotated relative to O-ring core 110. It should be noted that sealing members 105 b, 105 c and 105 e can be fabricated in a manner the same or similar to sealing members 105 a and 105 d.
FIG. 6 is a flow diagram of a method 200 of assembling an earth bit, in accordance with the invention. In this embodiment, method 200 includes a step 201 of providing a lug which carries a hub unit. Method 200 includes a step 202 of providing a sealing member which includes an O-ring core enclosed by a sleeve, wherein the sleeve includes a first seam extending around it. The sleeve can be slidingly engaged with the O-ring core. It should be noted that in some embodiments, the entire sleeve is slidingly engaged with the O-ring core and, in other embodiments, a portion of the sleeve is slidingly engaged with the O-ring core and another portion is not.
In accordance with the invention, the sleeve includes at least one seam extending around the O-ring core. In some embodiments, the portion of the sleeve that is engaged with the O-ring core is proximate to the seam and, in other embodiments, the portion of the sleeve that is engaged with the O-ring core is away from the seam.
Method 200 includes a step 203 of rotatably mounting a cutting cone to the hub unit so the sealing member forms a seal between the cutting cone and lug and/or hub unit. In some embodiments, the sleeve includes two seams wherein the seams extend annularly along the O-ring core. The two seams can be opposed to each other or unopposed. The sealing member is positioned so that the seam(s) is/are statically engaged with a surface, wherein the surface is an axial or radial surface of the earth bit.
FIG. 7 is a flow diagram of a method 210 of assembling an earth bit, in accordance with the invention. In this embodiment, method 210 includes a step 211 of providing earth bit components. The earth bit components can be of many different types, but in this embodiment, they include a cutting cone and a lug which carries a hub unit. Method 210 includes a step 212 of providing a sleeve and an O-ring core and enclosing the O-ring core with the sleeve to form a sealing member. The O-ring core is enclosed by the sleeve by wrapping the sleeve around it and forming one or more seams which extend annularly around the O-ring core. In accordance with the invention, the sleeve is slidingly engaged with the O-ring core. In some embodiments, the entire sleeve is slidingly engaged with the O-ring core and, in other embodiments, a portion of the sleeve is slidingly engaged with the O-ring core and another portion is not.
Method 210 includes a step 213 of rotatably mounting the cutting cone to the hub unit so the sealing member forms a seal between the cutting cone and lug and/or hub unit. The sealing member is positioned so that the seam(s) is/are statically engaged with a surface, wherein the surface is an axial or radial surface of the earth bit.
The embodiments of the invention described herein are exemplary and numerous modifications, variations and rearrangements can be readily envisioned to achieve substantially equivalent results, all of which are intended to be embraced within the spirit and scope of the invention.

Claims

1. An earth bit, comprising:

a cutting cone rotatably mounted to a lug with a hub unit; and

a sealing member positioned to provide a seal between the cutting cone and lug and/or hub unit, the sealing member including an O-ring core enclosed by a sleeve having a first seam extending around it.

2. The earth bit of claim 1, wherein the first seam engages a static sealing surface.

3. The earth bit of claim 1, further including a second seam which engages a static sealing surface.

4. The earth bit of claim 3, wherein the first and second seams extend along inner and outer portions of the O-ring core.

5. The earth bit of claim 1, further wherein the first seam restricts the rotation of the sleeve about the O-ring core in response to engaging the cutting cone, hub unit and/or lug.

6. The earth bit of claim 1, wherein the sleeve is slidingly engaged with the O-ring core.

7. An earth bit, comprising:

a cutting cone rotatably mounted to a lug with a hub unit; and

a sealing member positioned to provide a seal between the cutting cone and lug and/or hub unit, the sealing member including an O-ring core enclosed by a sleeve having first and second seams extending around it.

8. The earth bit of claim 7, wherein the first seam faces the hub unit and the second seam faces away from the hub unit.

9. The earth bit of claim 7, wherein the first and second seams oppose each other.

10. The earth bit of claim 7, wherein the sleeve includes first and second sleeve pieces coupled together by the first and second seams.

11. The earth bit of claim 7, wherein the sleeve includes wear resistant material with opposed ends seamed together.

12. The earth bit of claim 7, wherein the first and second seams extend annularly around the O-ring core.

13. A method of assembling an earth bit, comprising:

providing a lug which carries a hub unit;

providing a sealing member which includes an O-ring core and a sleeve, wherein the sleeve includes a first seam extending around the O-ring core; and

rotatably mounting a cutting cone to the hub unit so the sealing member forms a seal between the cutting cone and hub unit.

14. The method of claim 13, wherein the sleeve further includes a second seam extending around the O-ring core.

15. The method of claim 14, wherein the first and second seams oppose each other.

16. The method of claim 14, further including positioning the sealing member so the first seam faces the hub unit and the second seam faces away from the hub unit.

17. The method of claim 14, wherein the sleeve includes a third seam which extends at a non-zero angle relative to the first and second seams.

18. The method of claim 13, further enclosing the O-ring core with the sleeve.

19. The method of claim 13, further including forming the sleeve by coupling first and second sleeve pieces together.

20. The method of claim 13, further including wrapping the sleeve around the O-ring core and seaming its opposed sides together.