CA1090328A - Sealing system for an earth boring cutter - Google Patents
Sealing system for an earth boring cutterInfo
- Publication number
- CA1090328A CA1090328A CA317,021A CA317021A CA1090328A CA 1090328 A CA1090328 A CA 1090328A CA 317021 A CA317021 A CA 317021A CA 1090328 A CA1090328 A CA 1090328A
- Authority
- CA
- Canada
- Prior art keywords
- seal element
- cutter
- annular groove
- bearing shaft
- seal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000007789 sealing Methods 0.000 title abstract description 9
- 238000005096 rolling process Methods 0.000 claims abstract description 14
- 239000011435 rock Substances 0.000 claims description 9
- 230000006835 compression Effects 0.000 claims description 8
- 238000007906 compression Methods 0.000 claims description 8
- 239000000314 lubricant Substances 0.000 abstract description 32
- 239000012530 fluid Substances 0.000 abstract description 12
- 239000000463 material Substances 0.000 abstract description 12
- 238000005520 cutting process Methods 0.000 abstract description 9
- 238000005553 drilling Methods 0.000 abstract description 7
- 230000004888 barrier function Effects 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000005755 formation reaction Methods 0.000 description 6
- 238000005461 lubrication Methods 0.000 description 3
- 238000012856 packing Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- FSVJFNAIGNNGKK-UHFFFAOYSA-N 2-[cyclohexyl(oxo)methyl]-3,6,7,11b-tetrahydro-1H-pyrazino[2,1-a]isoquinolin-4-one Chemical compound C1C(C2=CC=CC=C2CC2)N2C(=O)CN1C(=O)C1CCCCC1 FSVJFNAIGNNGKK-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B10/00—Drill bits
- E21B10/08—Roller bits
- E21B10/22—Roller bits characterised by bearing, lubrication or sealing details
- E21B10/25—Roller bits characterised by bearing, lubrication or sealing details characterised by sealing details
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Fluid Mechanics (AREA)
- Environmental & Geological Engineering (AREA)
- Physics & Mathematics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Sealing Of Bearings (AREA)
- Earth Drilling (AREA)
Abstract
SEALING SYSTEM FOR AN EARTH BORING CUTTER
Abstract of the Disclosure A sealing system acts as a barrier to the drilling fluid, pulverized cuttings and other materials in the borehole preventing the materials from entering the bearing area of an earth boring cutter unit and retains lubricant inside the bearing area. At least one bearing pin extends from the body of an earth boring bit and a rolling cutter is mounted on the bearing pin.
A seal unit is located between the mouth of the cutter and the bearing pin. The radial to axial relationship of the seal unit is more than one-to-one and less than one-and-one-half-to-one.
The seal unit is compressed less than 10% when the rolling cutter is assembled on the bearing pin.
-1a-
Abstract of the Disclosure A sealing system acts as a barrier to the drilling fluid, pulverized cuttings and other materials in the borehole preventing the materials from entering the bearing area of an earth boring cutter unit and retains lubricant inside the bearing area. At least one bearing pin extends from the body of an earth boring bit and a rolling cutter is mounted on the bearing pin.
A seal unit is located between the mouth of the cutter and the bearing pin. The radial to axial relationship of the seal unit is more than one-to-one and less than one-and-one-half-to-one.
The seal unit is compressed less than 10% when the rolling cutter is assembled on the bearing pin.
-1a-
Description
: - `` 10903zl~
:
Background of the Invention - The present invention relates to the art of earth boring and, more particularly, to an earth boring cutter unit with improved means for sealing the bearings of the cutter unit from materials in the borehole and retaining lubricant within the bearing area. The present invention is especially adapted for use with cutter units in that type of bit popularly known as a three-cone rotary rock bit; however, its use is not restricted thereto, and the present invention can be used in other types of rock drilling cutter units.
. . .
A three-cone rotary rock bit consists of a main bit body adapted to be connected to a rotary drill string. The bit includes three individual rotatable cone cutters mounted on three ~; individual bearing pins extending from the main bit body. Bearing systems are provided between the cone cutters and the bearing pins to promote rotation of the cutters and means are provided on the outer surface of the cone cutters for disintegrating the earth formations as the bit and the cutters rotate. A sufficient supply of uncontaminated lubricant must be maintained proximate the bearing systems throughout the lifetime of the bit. Various forms of seals have been provided between the cone cutters and the bearing pins upon which they are mounted to retain lubricant and prevent contamination; however, the need for new sealing systems ~ .
is as acute today as any time in the history of rock drilling.
A three-cone rotary rock bit must operate under very ` severe conditions, and the size and geometry of the bit is restricted by the operating characteristics. At the same time, ` the economics of petroleum production demand a longer lifetime and improved performance from the bit. In attempting to provide an improved bit, new and improved materials have been developed for the cutting structure of the cone cutters. They have provided ;: ~r~
:
~ .
:.
",:
~0903'~8 a longer useful lifetime for the cone cutters. This has resulted in the bearing systems of the bit being often the first to fail during the drilling operation. Consequently, a need exists for new and improved bearing systems to extend the useful lifetime of the bit and to allow development of other elements that interact with the sealing and bearing systems. In attempting to improve the bearing systems, various seal systems have been provided to maintain the bearing area free of harmful materials and retain lubricant. In attempting to provide new sealing systems, great care must be taken that the overall capacity of the bearing systems is not reduced.
Description of Prior Art In U. S. Patent No. 3,765,495 to Henry W. Murdoch and - Percy W. Schumaucher, Jr. patented October 16, 1973, a drill bit seal is shown. An earth boring drill employing roller cutters is . provided with a new and improved seal to inhibit ingress of detritus into the cutter bearing area and egress of lubricant therefrom. The parts may be so arranged that when assembled, the seal is placed in hoop compression. The shape of the seal is such that its cross section is not overly compressed or displaced when - in operating position; this prevents undue compression set, wear and heating of the seal. Also, the seal has a greater radial cross sectional extent than axial extent by a ratio of at least one-and- ~ ~-one-half-to-one to conserve bearing space and to provide the necessary flexibility to accommodate the various movements of the cutter relative to the shaft upon which it is rotatably mounted.
In U. S. Patent No. 3,397,928 to E. M. Galle patented August 20, 1968, a seal means for drill bit bearings is shown.
The seal means includes a shaft rigidly secured to a drill bit body with a bearing surface formed thereon. A cutter element is rotatably mounted to said shaft and includes a bearing surface "
'':
10903'~8 thereon that opposes and engages the bearing surface on the shaft. A resilient packing ring is positioned in a groove in one of the surfaces. The packing ring, the groove and - an opposing surface are sized such that upon assembly of the cutter element upon the shaft the cross sectional thickness of the packing ring is compressed by not less than substantially 10% of this thickness prior to assembly of the cutter element upon the shaft.
Summary of the Invention ';~
r' 10 The present invention provides a sealing system for an earth boring cutter unit that acts as a barrier to the drilling fluid, pulverized cuttings and other materials in the borehole to prevent the materials from entering the bearing area of the cutter unit and retains lubricant within said bearing area.
According to the present invention there is provided an earth boring bit having a bit body, a bearing shaft extending from the bit body and a rotatable cutter , adapted to be rotatably mounted on the bearing shaft. A
shallow annular groove is provided in the rotatable cutter and a one piece seal element is positioned around the bearing shaft between the rotatable cutter and the bearing shaft.
The seal element is positioned in the annular groove and has a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent with a substantial portion of the seal element extending out of the shallow annular groove. The ~`
seal element is compressed less than substantially 10%
when compressed between the rotatable cut-ter and the bearing shaft.
.
The unique seal of the present invention can be shown to have a number of important features not existing "' cbr/~
`
.
~09032~
in the prior art described above. It is; however, to be understood that the scope of the present invention is : defined by the claims at the end of this specification and a general description of the prior art and distinctions thereover is not to be interpreted as limiting the coverage ~ of the present invention. The Murdoch and ..
. ' ':
. .
' ~ -3a-'' cbr/~
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- ~ ' - ' : .
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Schumaucher seal shown in U. S. Patent No. 3,765,495 would have a greater tendency to fall over than the seal element of the present invention because it tends to be taller than the seal element of the present invention. The seal element of the present invention takes up less of the critical bearing space than the " Murdoch and Schumaucher seal or the Galle seal shown in U. S.
Patent No. 3,397,928. The seal element of the present invention provides a greater surface area in uniform contact with the rolling cutter than any of the seal elements shown in the prior art. The above and other features and advantages of the present invention will become apparent upon consideration of the following detailed description of the invention when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings Figure 1 is an illustration of an earth boring bit constructed in accordance with the present invention.
Figure 2 is an enlarged view of a portion of the bit shown in Figure 1.
Figure 3 shows a side view of the seal element shown in Figures 1 and 2.
Figure 4 is a cross sectional view of the seal element shown in Figure 3 taken along lines 4-4.
Detailed Description of the Invention Referring now to Figure 1, a sectional view of one arm 18 of a three-cone rotary rock bit 10 is shown. It is to be understood that the structure of the other two arms are substantially identical to the arm 18. A cutter 14 is rotatably positioned on the journal portion or bearing pin 17 of the arm 18 and adapted to disintegrate the earth formations as the bit 10 is rotated. The bearing pin 17 projects from the cutter receiving surface 35 of the arm 18. The cutting structure 15 on the surface of cutter 14 ;
.
contacts and disintegrates the formations in a manner that is well known in the art. The cutting structure 15 is shown in the form of tungsten carbide inserts. However, it is to be understood that other cutting structures such as steel teeth may be used as the cutting structure on the cone cutter 14.
The body 13 of the bit 10 includes an upper threaded portion 12 that allows the bit 10 to be connected to the lower end of a rotary drill string (not shown). The bit 10 also includes a central passageway 16 extending along the central axis of the bit to allow drilling fluid to enter from the upper section of the drill string (not shown) immediately above and pass downward to the bottom of the well bore to flush cuttings and drilling debris ~-from the well bore.
A plurality of bearing systems are located in the bearing area between the cutter 14 and the bearing pin 17. The bearing systems in the bearing area include an outer friction bearing 19, a series of ball bearings 20, an inner friction bearing 21, and a thrust button 22. A seal unit 11 is positioned between the cutter 14 and the bearing pin 17. The seal unit 11 retains lubricant in the bearing area around the bearing systems and prevents any materials in the well bore from entering the bearing area.
Passageways 23 and 24 are provided to allow lubricant to be transmitted to the bearing systems. The passageway 24, as shown, also allows the balls that make up the ball bearing system 20 to ; 25 be inserted into position after the cone cutter 14 is placed on the bearing pin 18. The series of ball bearings 20 serves to lock ` the cone cutter 14 on bearing pin 18. After the balls are in place, a plug 25 is inserted into the passageway 24 and welded therein by weld 26. Plug 25 has a reduced diameter throughout the major portion of its length to allow lubricant to be transmitted to the bearing area. The additional passageways 23 extend from passage-way 24 to the bearing area to insure a sufficient supply of lubricant to bearings 19, 20, 21 and 22.
:
. .
-` lOgO3Z8 A bore 30 extends into the body 13 from the surface ` of the bit body. A passage 31 extends from the bore 30 to the passageway 24. A lubricant reservoir 32 is located in the bore 30. The lubricant reservoir 32 is located between a flexible diaphragm 28 and a reservoir cap 34. An O-ring seal prevents borehole fluid from by-passing the upper portion of the reservoir cap 34 and lubricant within the lubricant reservoir 32 from escaping into the borehole. A retaining ring 33 holds reservoir cap 34 in position in bore 30. The flexible diaphragm 28 prevents lubricant in the lubricant reservoir 32 from escaping into the ; bore 30 and fluid in the borehole that has entered bore 30 through passage 27 from entering the lubricant reservoir 32. Lubricant within the lubricant reservoir 32 is channeled into the passage 31 through opening 29 and is directed to the bearings.
Referring now to Figure 2, an enlarged view of a portion ' of the arm 18, the cone 14 and seal unit 11 is shown. The seal unit 11 is positioned between a surface 36 on the bearing pin 17 ~ and a groove 38 in the cone cutter 14. The groove 38 includes :` radii 39 and 40 to avoid sharp corners that would concentrate stress. The seal unit 11 is also positioned between the cutter - receiving surface 35 and a surface 37 on the bearing element 19.
- The pressure of fluid outside the bit 10 will tend to force the seal 11 toward the surface 37 on the bearing element 19 and the surface 36 on the bearing pin 17, thereby establishing a barrier to fluid and materials in the borehole. Internal pressure of , lubricant within the bit will tend to force the seal 11 outward toward the cutter receiving surface 35 and the surface 38 on the , cone cutter 14, thereby blocking flow of lubricant from the bit.
In both situations the integrity of the seal will be maintained.
Referring now to Figures 3 and 4, the seal unit 11 is shown in greater detail. The cross section of the seal unit 11 is elongated in the radial direction. As shown in Figure 4, the ~' :
1(~903Z8 radial dimension R of the seal unit 11 is greater than the axial dimension A. It is however to be understood that the radial dimension R of the seal 11 is less than one-and-one-half times the axial dimension A. When the cutter 14 is assembled upon the bearing pin 17, the seal 11 is compressed. The seal 11 is generally compressed 10~ or less of the radial dimension R. It is to be understood that because of tolerance variations the compression on the seal in some circumstances might be greater than 10%.
The structural details of an earth boring bit 10 constructed in accordance with the present invention having been described, the operation of the bit 10 will now be considered with reference to Figures 1-4. The lubrication system of the bit 10 is filled with a suitable lubricant. The area within the flexible diaphragm 28 provides a reservoir of lubricant. The flexible diaphragm 28 seals the lower end of the lubricant reservoir and is held in place by the cap 34. The bit 10 will be lowered into a well bore until the cutter 14 contacts the earth formations at the bottom of the borehole. The hydrostatic pressure of fluid in the well bore is substantial. The lubrication system of the bit 10 allows the pressure of fluid in the well bore to be transmitted to the lubricant reservoir through passage 27 to the lubricant through diaphragm 28. This allows the pressure of lubricant inside the bit and fluid in the borehole to beequalized as the bit 10 is moved through the borehole. Lubricant from the lubricant reservoir can migrate through passages 3Ii 24 and 23 and be transmitted to the bearing systems.
The bit 10 is rotated and thrust downward, thrusting the cutter 14 against the earth formations. Continued rotation with the weight of the drill string applying a thrust force to the bit 10 causes the cutters to disintegrate the formations and form the desired borehole. The present invention provides a seal unit 11 in the cone mouth of the bit which will act as a barrier to the pulverized cuttings, the borehole fluid and any -lO90;~Z8 other materials in the borehole. The seal unit 11 acts to prevent these materials from entering the bearing area through the cone mouth opening, thus providing an uncontaminated environ-;` ment for the metal bearing elements and eliminating the abrasive wearing action of foreign materials in the bearing area. The ~` lubricant is retained within the bit 10 by the seal unit 11 to assure a long lifetime for the bearing systems.
External pressure of fluid outside the bit 10 will movethe seal 11 against the surface 36 on the bearing pin 17 and the surface 37 on the bearing element 19 providing a positive seal.
Internal pressure within the lubricant inside the bit 10 will move the seal 11 outward against sidewall 41 of the groove 38, tending - -to support the seal and promote rotation of the seal 11 with the cutter 14 with minimal rotational contact with the cutter receiving surface 35.
The desired closure of the area between the cutter 14 -and the bearing pin 17 is maintained from groove 38 to seal unit 11 to bearing pin 17 due to the radial squeeze of 10% or less of the relaxed dimension R of the seal unit 11. The ratio of R-to-A -of more than one-to-one provides a sufficiently large R dimension of seal unit 11 to reduce the required squeeze to 10% or less while maintaining sufficient interference on the seal to keep the seal unit 11 in contact with the bearing pin 17 and cutter 14 at all times and providing the necessary clearance in the bearing elements to permit free rotation of the cutter 14. The ratio of R-to-A of less than one-and-one-half-to-one keeps the proportions - of the seal sufficiently stable to avoid tilting of the seal to a diagonal position which could relax some of the radial squeeze on the seal element 11. A ratio of R-to-A of more than one-and-one-30 half-to-one would require additional guide means to prevent undesirable misalignment of the radial cross section of the seal.
. .
109032~
The seal element of the present invention takes up less of the critical bearing space for bearing element 19 than the Murdoch and Schumaucher seal shown in U. S. Patent No.
3,765,495. The seal element of the present invention provides i 5 a greater surface area in uniform contact with the rolling cutter than any of the seal elements shown in the prior art. The seal element 11 may be installed in the groove 38 in hoop compression with the flat outer surface of seal unit in intimate contact with groove 38~ The seal element will rotate with the cutter 14 and provide a dynamic seal to maintain the integrity of the lubrication system of the bit 10.
The seal element of the present invention provides equal squeeze to the Galle seal shown in U. S. Patent No.
3,397,928 but as a lower percentage of the squeezed seal cross section dimension. The lower percentage squeeze while maintaining sealing contact results in a lower contact pressure between the seal 11 and the metal surface, resulting in a reduced wear rate.
A rock boring cutter as for example for a large diameter earth boring head can be similarly sealed on a supporting bearing shaft.
A rock contacting roller as for example on a drill string stabilizer or reamer can be similarly sealed on a supporting bearing shaft.
:
Background of the Invention - The present invention relates to the art of earth boring and, more particularly, to an earth boring cutter unit with improved means for sealing the bearings of the cutter unit from materials in the borehole and retaining lubricant within the bearing area. The present invention is especially adapted for use with cutter units in that type of bit popularly known as a three-cone rotary rock bit; however, its use is not restricted thereto, and the present invention can be used in other types of rock drilling cutter units.
. . .
A three-cone rotary rock bit consists of a main bit body adapted to be connected to a rotary drill string. The bit includes three individual rotatable cone cutters mounted on three ~; individual bearing pins extending from the main bit body. Bearing systems are provided between the cone cutters and the bearing pins to promote rotation of the cutters and means are provided on the outer surface of the cone cutters for disintegrating the earth formations as the bit and the cutters rotate. A sufficient supply of uncontaminated lubricant must be maintained proximate the bearing systems throughout the lifetime of the bit. Various forms of seals have been provided between the cone cutters and the bearing pins upon which they are mounted to retain lubricant and prevent contamination; however, the need for new sealing systems ~ .
is as acute today as any time in the history of rock drilling.
A three-cone rotary rock bit must operate under very ` severe conditions, and the size and geometry of the bit is restricted by the operating characteristics. At the same time, ` the economics of petroleum production demand a longer lifetime and improved performance from the bit. In attempting to provide an improved bit, new and improved materials have been developed for the cutting structure of the cone cutters. They have provided ;: ~r~
:
~ .
:.
",:
~0903'~8 a longer useful lifetime for the cone cutters. This has resulted in the bearing systems of the bit being often the first to fail during the drilling operation. Consequently, a need exists for new and improved bearing systems to extend the useful lifetime of the bit and to allow development of other elements that interact with the sealing and bearing systems. In attempting to improve the bearing systems, various seal systems have been provided to maintain the bearing area free of harmful materials and retain lubricant. In attempting to provide new sealing systems, great care must be taken that the overall capacity of the bearing systems is not reduced.
Description of Prior Art In U. S. Patent No. 3,765,495 to Henry W. Murdoch and - Percy W. Schumaucher, Jr. patented October 16, 1973, a drill bit seal is shown. An earth boring drill employing roller cutters is . provided with a new and improved seal to inhibit ingress of detritus into the cutter bearing area and egress of lubricant therefrom. The parts may be so arranged that when assembled, the seal is placed in hoop compression. The shape of the seal is such that its cross section is not overly compressed or displaced when - in operating position; this prevents undue compression set, wear and heating of the seal. Also, the seal has a greater radial cross sectional extent than axial extent by a ratio of at least one-and- ~ ~-one-half-to-one to conserve bearing space and to provide the necessary flexibility to accommodate the various movements of the cutter relative to the shaft upon which it is rotatably mounted.
In U. S. Patent No. 3,397,928 to E. M. Galle patented August 20, 1968, a seal means for drill bit bearings is shown.
The seal means includes a shaft rigidly secured to a drill bit body with a bearing surface formed thereon. A cutter element is rotatably mounted to said shaft and includes a bearing surface "
'':
10903'~8 thereon that opposes and engages the bearing surface on the shaft. A resilient packing ring is positioned in a groove in one of the surfaces. The packing ring, the groove and - an opposing surface are sized such that upon assembly of the cutter element upon the shaft the cross sectional thickness of the packing ring is compressed by not less than substantially 10% of this thickness prior to assembly of the cutter element upon the shaft.
Summary of the Invention ';~
r' 10 The present invention provides a sealing system for an earth boring cutter unit that acts as a barrier to the drilling fluid, pulverized cuttings and other materials in the borehole to prevent the materials from entering the bearing area of the cutter unit and retains lubricant within said bearing area.
According to the present invention there is provided an earth boring bit having a bit body, a bearing shaft extending from the bit body and a rotatable cutter , adapted to be rotatably mounted on the bearing shaft. A
shallow annular groove is provided in the rotatable cutter and a one piece seal element is positioned around the bearing shaft between the rotatable cutter and the bearing shaft.
The seal element is positioned in the annular groove and has a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent with a substantial portion of the seal element extending out of the shallow annular groove. The ~`
seal element is compressed less than substantially 10%
when compressed between the rotatable cut-ter and the bearing shaft.
.
The unique seal of the present invention can be shown to have a number of important features not existing "' cbr/~
`
.
~09032~
in the prior art described above. It is; however, to be understood that the scope of the present invention is : defined by the claims at the end of this specification and a general description of the prior art and distinctions thereover is not to be interpreted as limiting the coverage ~ of the present invention. The Murdoch and ..
. ' ':
. .
' ~ -3a-'' cbr/~
!
- ~ ' - ' : .
lO9()~Z~
Schumaucher seal shown in U. S. Patent No. 3,765,495 would have a greater tendency to fall over than the seal element of the present invention because it tends to be taller than the seal element of the present invention. The seal element of the present invention takes up less of the critical bearing space than the " Murdoch and Schumaucher seal or the Galle seal shown in U. S.
Patent No. 3,397,928. The seal element of the present invention provides a greater surface area in uniform contact with the rolling cutter than any of the seal elements shown in the prior art. The above and other features and advantages of the present invention will become apparent upon consideration of the following detailed description of the invention when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings Figure 1 is an illustration of an earth boring bit constructed in accordance with the present invention.
Figure 2 is an enlarged view of a portion of the bit shown in Figure 1.
Figure 3 shows a side view of the seal element shown in Figures 1 and 2.
Figure 4 is a cross sectional view of the seal element shown in Figure 3 taken along lines 4-4.
Detailed Description of the Invention Referring now to Figure 1, a sectional view of one arm 18 of a three-cone rotary rock bit 10 is shown. It is to be understood that the structure of the other two arms are substantially identical to the arm 18. A cutter 14 is rotatably positioned on the journal portion or bearing pin 17 of the arm 18 and adapted to disintegrate the earth formations as the bit 10 is rotated. The bearing pin 17 projects from the cutter receiving surface 35 of the arm 18. The cutting structure 15 on the surface of cutter 14 ;
.
contacts and disintegrates the formations in a manner that is well known in the art. The cutting structure 15 is shown in the form of tungsten carbide inserts. However, it is to be understood that other cutting structures such as steel teeth may be used as the cutting structure on the cone cutter 14.
The body 13 of the bit 10 includes an upper threaded portion 12 that allows the bit 10 to be connected to the lower end of a rotary drill string (not shown). The bit 10 also includes a central passageway 16 extending along the central axis of the bit to allow drilling fluid to enter from the upper section of the drill string (not shown) immediately above and pass downward to the bottom of the well bore to flush cuttings and drilling debris ~-from the well bore.
A plurality of bearing systems are located in the bearing area between the cutter 14 and the bearing pin 17. The bearing systems in the bearing area include an outer friction bearing 19, a series of ball bearings 20, an inner friction bearing 21, and a thrust button 22. A seal unit 11 is positioned between the cutter 14 and the bearing pin 17. The seal unit 11 retains lubricant in the bearing area around the bearing systems and prevents any materials in the well bore from entering the bearing area.
Passageways 23 and 24 are provided to allow lubricant to be transmitted to the bearing systems. The passageway 24, as shown, also allows the balls that make up the ball bearing system 20 to ; 25 be inserted into position after the cone cutter 14 is placed on the bearing pin 18. The series of ball bearings 20 serves to lock ` the cone cutter 14 on bearing pin 18. After the balls are in place, a plug 25 is inserted into the passageway 24 and welded therein by weld 26. Plug 25 has a reduced diameter throughout the major portion of its length to allow lubricant to be transmitted to the bearing area. The additional passageways 23 extend from passage-way 24 to the bearing area to insure a sufficient supply of lubricant to bearings 19, 20, 21 and 22.
:
. .
-` lOgO3Z8 A bore 30 extends into the body 13 from the surface ` of the bit body. A passage 31 extends from the bore 30 to the passageway 24. A lubricant reservoir 32 is located in the bore 30. The lubricant reservoir 32 is located between a flexible diaphragm 28 and a reservoir cap 34. An O-ring seal prevents borehole fluid from by-passing the upper portion of the reservoir cap 34 and lubricant within the lubricant reservoir 32 from escaping into the borehole. A retaining ring 33 holds reservoir cap 34 in position in bore 30. The flexible diaphragm 28 prevents lubricant in the lubricant reservoir 32 from escaping into the ; bore 30 and fluid in the borehole that has entered bore 30 through passage 27 from entering the lubricant reservoir 32. Lubricant within the lubricant reservoir 32 is channeled into the passage 31 through opening 29 and is directed to the bearings.
Referring now to Figure 2, an enlarged view of a portion ' of the arm 18, the cone 14 and seal unit 11 is shown. The seal unit 11 is positioned between a surface 36 on the bearing pin 17 ~ and a groove 38 in the cone cutter 14. The groove 38 includes :` radii 39 and 40 to avoid sharp corners that would concentrate stress. The seal unit 11 is also positioned between the cutter - receiving surface 35 and a surface 37 on the bearing element 19.
- The pressure of fluid outside the bit 10 will tend to force the seal 11 toward the surface 37 on the bearing element 19 and the surface 36 on the bearing pin 17, thereby establishing a barrier to fluid and materials in the borehole. Internal pressure of , lubricant within the bit will tend to force the seal 11 outward toward the cutter receiving surface 35 and the surface 38 on the , cone cutter 14, thereby blocking flow of lubricant from the bit.
In both situations the integrity of the seal will be maintained.
Referring now to Figures 3 and 4, the seal unit 11 is shown in greater detail. The cross section of the seal unit 11 is elongated in the radial direction. As shown in Figure 4, the ~' :
1(~903Z8 radial dimension R of the seal unit 11 is greater than the axial dimension A. It is however to be understood that the radial dimension R of the seal 11 is less than one-and-one-half times the axial dimension A. When the cutter 14 is assembled upon the bearing pin 17, the seal 11 is compressed. The seal 11 is generally compressed 10~ or less of the radial dimension R. It is to be understood that because of tolerance variations the compression on the seal in some circumstances might be greater than 10%.
The structural details of an earth boring bit 10 constructed in accordance with the present invention having been described, the operation of the bit 10 will now be considered with reference to Figures 1-4. The lubrication system of the bit 10 is filled with a suitable lubricant. The area within the flexible diaphragm 28 provides a reservoir of lubricant. The flexible diaphragm 28 seals the lower end of the lubricant reservoir and is held in place by the cap 34. The bit 10 will be lowered into a well bore until the cutter 14 contacts the earth formations at the bottom of the borehole. The hydrostatic pressure of fluid in the well bore is substantial. The lubrication system of the bit 10 allows the pressure of fluid in the well bore to be transmitted to the lubricant reservoir through passage 27 to the lubricant through diaphragm 28. This allows the pressure of lubricant inside the bit and fluid in the borehole to beequalized as the bit 10 is moved through the borehole. Lubricant from the lubricant reservoir can migrate through passages 3Ii 24 and 23 and be transmitted to the bearing systems.
The bit 10 is rotated and thrust downward, thrusting the cutter 14 against the earth formations. Continued rotation with the weight of the drill string applying a thrust force to the bit 10 causes the cutters to disintegrate the formations and form the desired borehole. The present invention provides a seal unit 11 in the cone mouth of the bit which will act as a barrier to the pulverized cuttings, the borehole fluid and any -lO90;~Z8 other materials in the borehole. The seal unit 11 acts to prevent these materials from entering the bearing area through the cone mouth opening, thus providing an uncontaminated environ-;` ment for the metal bearing elements and eliminating the abrasive wearing action of foreign materials in the bearing area. The ~` lubricant is retained within the bit 10 by the seal unit 11 to assure a long lifetime for the bearing systems.
External pressure of fluid outside the bit 10 will movethe seal 11 against the surface 36 on the bearing pin 17 and the surface 37 on the bearing element 19 providing a positive seal.
Internal pressure within the lubricant inside the bit 10 will move the seal 11 outward against sidewall 41 of the groove 38, tending - -to support the seal and promote rotation of the seal 11 with the cutter 14 with minimal rotational contact with the cutter receiving surface 35.
The desired closure of the area between the cutter 14 -and the bearing pin 17 is maintained from groove 38 to seal unit 11 to bearing pin 17 due to the radial squeeze of 10% or less of the relaxed dimension R of the seal unit 11. The ratio of R-to-A -of more than one-to-one provides a sufficiently large R dimension of seal unit 11 to reduce the required squeeze to 10% or less while maintaining sufficient interference on the seal to keep the seal unit 11 in contact with the bearing pin 17 and cutter 14 at all times and providing the necessary clearance in the bearing elements to permit free rotation of the cutter 14. The ratio of R-to-A of less than one-and-one-half-to-one keeps the proportions - of the seal sufficiently stable to avoid tilting of the seal to a diagonal position which could relax some of the radial squeeze on the seal element 11. A ratio of R-to-A of more than one-and-one-30 half-to-one would require additional guide means to prevent undesirable misalignment of the radial cross section of the seal.
. .
109032~
The seal element of the present invention takes up less of the critical bearing space for bearing element 19 than the Murdoch and Schumaucher seal shown in U. S. Patent No.
3,765,495. The seal element of the present invention provides i 5 a greater surface area in uniform contact with the rolling cutter than any of the seal elements shown in the prior art. The seal element 11 may be installed in the groove 38 in hoop compression with the flat outer surface of seal unit in intimate contact with groove 38~ The seal element will rotate with the cutter 14 and provide a dynamic seal to maintain the integrity of the lubrication system of the bit 10.
The seal element of the present invention provides equal squeeze to the Galle seal shown in U. S. Patent No.
3,397,928 but as a lower percentage of the squeezed seal cross section dimension. The lower percentage squeeze while maintaining sealing contact results in a lower contact pressure between the seal 11 and the metal surface, resulting in a reduced wear rate.
A rock boring cutter as for example for a large diameter earth boring head can be similarly sealed on a supporting bearing shaft.
A rock contacting roller as for example on a drill string stabilizer or reamer can be similarly sealed on a supporting bearing shaft.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An earth boring bit, comprising:
a bit body;
a bearing shaft extending from said bit body;
a rotatable cutter adapted to be rotatably mounted on said bearing shaft;
a shallow annular groove in said rotatable cutter; and a one piece seal element positioned around said bearing shaft between said rotatable cutter and said bearing shaft, said seal element positioned in said annular groove and having a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent with a substantial portion of said seal element extending out of said shallow annular groove and said seal element being compressed less than substantially 10%
when compressed between said rotatable cutter and said bearing shaft.
a bit body;
a bearing shaft extending from said bit body;
a rotatable cutter adapted to be rotatably mounted on said bearing shaft;
a shallow annular groove in said rotatable cutter; and a one piece seal element positioned around said bearing shaft between said rotatable cutter and said bearing shaft, said seal element positioned in said annular groove and having a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent with a substantial portion of said seal element extending out of said shallow annular groove and said seal element being compressed less than substantially 10%
when compressed between said rotatable cutter and said bearing shaft.
2. An earth boring bit, comprising:
a bit body;
a bearing shaft extending from said bit body;
a rotating cutter element adapted to be rotatably mounted on said bearing shaft;
a shallow annular groove in said rotating cutter element, said shallow annular groove having a bottom; and a one piece seal element positioned around said bearing shaft between said rotating cutter element and said bearing shaft, said seal element positioned in said annular groove and having an outer surface that is in intimate contact with the bottom of said shallow annular groove and a cross-section with a radial extent that is greater than its axial extent out less than one-and-one-half times its axial extent with a substantial portion of said seal element extending out of said shallow annular groove and wherein said seal element is in hoop compression so that said outer surface of said seal element is maintained in intimate contact with the bottom of said shallow annular groove and seal element will rotate with said rotating cutter element, said seal element being compressed less than substantially 10%
when compressed between said rotating cutter element and said bearing shaft.
a bit body;
a bearing shaft extending from said bit body;
a rotating cutter element adapted to be rotatably mounted on said bearing shaft;
a shallow annular groove in said rotating cutter element, said shallow annular groove having a bottom; and a one piece seal element positioned around said bearing shaft between said rotating cutter element and said bearing shaft, said seal element positioned in said annular groove and having an outer surface that is in intimate contact with the bottom of said shallow annular groove and a cross-section with a radial extent that is greater than its axial extent out less than one-and-one-half times its axial extent with a substantial portion of said seal element extending out of said shallow annular groove and wherein said seal element is in hoop compression so that said outer surface of said seal element is maintained in intimate contact with the bottom of said shallow annular groove and seal element will rotate with said rotating cutter element, said seal element being compressed less than substantially 10%
when compressed between said rotating cutter element and said bearing shaft.
3. An earth boring tool, comprising:
a body portion;
a bearing shaft extending from said body portion;
a rolling member adapted to be rotatably mounted on said bearing shaft and rotate about said bearing shaft;
a shallow annular groove in said rolling member, said shallow annular groove having a flat bottom; and a one piece seal element positioned around said bearing shaft between said rolling member and said bearing shaft, said seal element positioned in said shallow annular groove and having a flat outer surface that is in intimate contact with the flat bottom of said shallow annular groove and a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent with a substantial portion of said seal element extending out of said annular groove and wherein said seal element is in hoop compression so that said flat outer surface of said seal element will remain in intimate contact with said flat bottom of said shallow annular groove and said seal element will rotate with said rolling member, said seal element being compressed less than substantially 10% when compressed between said rolling member and said bearing shaft.
a body portion;
a bearing shaft extending from said body portion;
a rolling member adapted to be rotatably mounted on said bearing shaft and rotate about said bearing shaft;
a shallow annular groove in said rolling member, said shallow annular groove having a flat bottom; and a one piece seal element positioned around said bearing shaft between said rolling member and said bearing shaft, said seal element positioned in said shallow annular groove and having a flat outer surface that is in intimate contact with the flat bottom of said shallow annular groove and a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent with a substantial portion of said seal element extending out of said annular groove and wherein said seal element is in hoop compression so that said flat outer surface of said seal element will remain in intimate contact with said flat bottom of said shallow annular groove and said seal element will rotate with said rolling member, said seal element being compressed less than substantially 10% when compressed between said rolling member and said bearing shaft.
4. A rotary rock bit, comprising:
a bit body;
a bearing shaft extending from said bit body;
a rolling cutter adapted to rotate about said bearing shaft, said rolling cutter having an open mouth and a shallow annular groove within said open mouth, said annular groove having a flat bottom; and a one piece seal element positioned around said bearing shaft within said open mouth and located between said bearing shaft and said rolling cutter, said seal element having a flat outer surface that is in intimate contact with the flat bottom of said annular groove and a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent and wherein said seal element is in hoop compression so that said flat outer surface of said seal element is maintained in intimate contact with the flat bottom of said annular groove and said seal element will rotate with said rolling cutter, said seal element being compressed less than substantially 10% when compressed between said rolling cutter and said bearing shaft, said seal element flat outer surface being substantially equal to said axial extent of the seal element with a substantial portion of said seal element extending out of said shallow annular groove.
a bit body;
a bearing shaft extending from said bit body;
a rolling cutter adapted to rotate about said bearing shaft, said rolling cutter having an open mouth and a shallow annular groove within said open mouth, said annular groove having a flat bottom; and a one piece seal element positioned around said bearing shaft within said open mouth and located between said bearing shaft and said rolling cutter, said seal element having a flat outer surface that is in intimate contact with the flat bottom of said annular groove and a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent and wherein said seal element is in hoop compression so that said flat outer surface of said seal element is maintained in intimate contact with the flat bottom of said annular groove and said seal element will rotate with said rolling cutter, said seal element being compressed less than substantially 10% when compressed between said rolling cutter and said bearing shaft, said seal element flat outer surface being substantially equal to said axial extent of the seal element with a substantial portion of said seal element extending out of said shallow annular groove.
5. An earth boring bit, comprising:
a bit body, said bit body having a cutter receiving surface;
a bearing shaft extending from said bit body at said cutter receiving surface;
a rotating cone cutter adapted to be rotatably mounted on said bearing shaft, said rotating cone cutter having a cone mouth and a shallow annular groove within said cone mouth, said shallow annular groove having a flat bottom;
a bearing element located between said bearing shaft and said cutter proximate said shallow annular groove; and a one piece seal element positioned around said bearing shaft within said cone mouth and located between said bearing shaft and said rotating cone cutter and between said bearing element and said cutter receiving surface, said seal element having a flat outer surface that is in intimate contact with the flat bottom of said annular groove and a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent and wherein said seal element is compressed less than substantially 10% when compressed between said rotating cone cutter and said bearing shaft, said seal element flat outer surface being substantially equal to said axial extent of the seal element, said flat outer surface being positioned in said shallow annular groove in said rotating cone cutter with a substantial portion of said seal unit extending out of said shallow annular groove and said flat outer surface being in intimate contact with the flat bottom of said annular groove with said seal element being in hoop compression so that said seal element will rotate with said rotating cutter.
a bit body, said bit body having a cutter receiving surface;
a bearing shaft extending from said bit body at said cutter receiving surface;
a rotating cone cutter adapted to be rotatably mounted on said bearing shaft, said rotating cone cutter having a cone mouth and a shallow annular groove within said cone mouth, said shallow annular groove having a flat bottom;
a bearing element located between said bearing shaft and said cutter proximate said shallow annular groove; and a one piece seal element positioned around said bearing shaft within said cone mouth and located between said bearing shaft and said rotating cone cutter and between said bearing element and said cutter receiving surface, said seal element having a flat outer surface that is in intimate contact with the flat bottom of said annular groove and a cross-section with a radial extent that is greater than its axial extent but less than one-and-one-half times its axial extent and wherein said seal element is compressed less than substantially 10% when compressed between said rotating cone cutter and said bearing shaft, said seal element flat outer surface being substantially equal to said axial extent of the seal element, said flat outer surface being positioned in said shallow annular groove in said rotating cone cutter with a substantial portion of said seal unit extending out of said shallow annular groove and said flat outer surface being in intimate contact with the flat bottom of said annular groove with said seal element being in hoop compression so that said seal element will rotate with said rotating cutter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US86772978A | 1978-01-09 | 1978-01-09 | |
| US867,729 | 1978-01-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1090328A true CA1090328A (en) | 1980-11-25 |
Family
ID=25350365
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA317,021A Expired CA1090328A (en) | 1978-01-09 | 1978-11-28 | Sealing system for an earth boring cutter |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1090328A (en) |
| GB (1) | GB2012375A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4666001A (en) * | 1983-10-17 | 1987-05-19 | Hughes Tool Company - Usa | Earth boring bit with improved rigid face seal assembly |
| US5842701A (en) * | 1996-10-08 | 1998-12-01 | Smith International, Inc. | Dual functioning seal for rock bits |
| GB2335936B (en) | 1998-04-02 | 2002-10-02 | Smith International | Multi-piece rotary cone drill bit seal |
| CN114320163B (en) * | 2022-03-14 | 2022-05-10 | 西南石油大学 | Sealing element for roller bit and roller bit |
-
1978
- 1978-11-28 CA CA317,021A patent/CA1090328A/en not_active Expired
- 1978-12-11 GB GB7848006A patent/GB2012375A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB2012375A (en) | 1979-07-25 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |