SEAL FOR AN EARTH BIT
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.
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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 INVENTION1. 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 INVENTIONThe 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.
In accordance with the invention, earth bit 100 includes a sealing member 105 (
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.
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) (
In another example, sleeve 111 includes seam(s) (not shown) positioned between inner and outer portions 112a and 112b of O-ring core 110. For example, the seams can be positioned proximate to upper and lower portions 113a and 113b (
The engagement of seam 116 with cutting cone 103 allows sealing member 105a 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 105a is decreased when it allows more lubricant and abrasive material to flow therethrough.
It should be noted that sealing member 105b 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 113b of O-ring core 110, as will be discussed in more detail presently.
In this embodiment, seam 115 engages radial surface 130, seam 116 engages axial surface 132 and seam 117 engages axial surface 133 (
In this embodiment, seam 115 engages axial surface 132 and seam 117 engages axial surface 133 (
It should be noted that seams 115, 116 and 117 can be formed in many different ways, such as by stitching sleeve pieces 111a, 111b and 111c 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 111a, 111b and 111c proximate to seams 115, 116 and 117 can overlap.
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 (
In this embodiment, sleeve pieces 111a and 111b 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 111a and 111b are coupled together by seams 115 and 117. By seaming together opposed sides 120 and 121, sleeve pieces 111a and 111a can be wrapped around O-ring core 110 without attaching them thereto, such as with adhesives or bonding. In this way, sleeve pieces 111a and 111b are slidingly engaged with O-ring core 110 instead of fixedly attached thereto. Sleeve pieces 111a and 111b are slidingly engaged with O-ring core 110 so that pieces 111a and 111b can be rotated relative to O-ring core 110. It should be noted that sealing members 105b, 105c and 105e can be fabricated in a manner the same or similar to sealing members 105a and 105d.
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.
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.
Type: Application
Filed: Aug 18, 2007
Publication Date: Feb 21, 2008
Applicant: ATLAS COPCO SECOROC LLC (Grand Prairie, TX)
Inventor: Gregory W. Peterson (Fort Worth, TX)
Application Number: 11/840,959
International Classification: E21B 10/22 (20060101); E21B 10/00 (20060101);