EP0837215A2 - Anneau de retenue pour molettes de coupe - Google Patents

Anneau de retenue pour molettes de coupe Download PDF

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Publication number
EP0837215A2
EP0837215A2 EP97308197A EP97308197A EP0837215A2 EP 0837215 A2 EP0837215 A2 EP 0837215A2 EP 97308197 A EP97308197 A EP 97308197A EP 97308197 A EP97308197 A EP 97308197A EP 0837215 A2 EP0837215 A2 EP 0837215A2
Authority
EP
European Patent Office
Prior art keywords
bearing
cutter
threaded ring
threads
rolling cutter
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.)
Granted
Application number
EP97308197A
Other languages
German (de)
English (en)
Other versions
EP0837215B1 (fr
EP0837215A3 (fr
Inventor
Randall R. Price
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ReedHycalog UK Ltd
Original Assignee
Camco International Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Camco International Inc filed Critical Camco International Inc
Publication of EP0837215A2 publication Critical patent/EP0837215A2/fr
Publication of EP0837215A3 publication Critical patent/EP0837215A3/fr
Application granted granted Critical
Publication of EP0837215B1 publication Critical patent/EP0837215B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • 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
    • E21B10/20—Roller bits characterised by detachable or adjustable parts, e.g. legs or axles

Definitions

  • This invention relates to an improved mechanism for assembling cutters on supporting bearing spindles in roller cutter earth boring bits.
  • the invention causes the retention bearing mechanism to remain centred within the bearing system of a cutter in an earth boring bit cutter during operation, thereby providing greater reliability and reduced wellbore drilling costs.
  • Cutter retention systems for rolling cutter drill bits are well known in the art.
  • ball bearings can be inserted through a hole in the body to fill a groove between the rolling cutter and the bit body as shown in U.S. Patent No. 3,989,315.
  • a snap ring can be positioned in the same general area as the ball bearings as shown in U.S. Patent No. 4,236,764.
  • a split threaded thrust bearing member can be installed in the bit as shown in U.S. Patent No. 3,971,600.
  • Other threaded ring rolling cutter retention mechanisms are shown in U.S. Pat. Nos. 4,911,255; 4,991,671; 5,012,701; 5,024,539 and 5,383,525.
  • the threaded ring bearing retention mechanism has been found to provide superior cutter retention performance as compared to the other retention systems as long as the threaded ring remains securely seated within the rolling cutter. If the threaded ring becomes loosened from its intended position, the resulting excessive axial cutter displacement is detrimental to the cutter seal, resulting in premature bearing failure and shorter than expected bit life. As described in U.S. Patent No. 5,383,525, the threaded ring is designed to resist unseating after the bit is assembled by provision of mechanical alterations to the intermeshing threads so that even with the occasional reverse rotation of the rolling cutter the threaded ring will not loosen.
  • the fastener's diameter is generally several times greater than its length.
  • the rolling cutter is normally made with alloy steels hardened to about 40 Rockwell 'C' with yield strengths greater than 150,000 PSI.
  • the design geometry of the cutters maximizes stiffness in the bearing area and minimizes plastic and elastic deformations. For these reasons, there is no known practical method to apply enough torque to this type of threaded assembly to ensure enough elastic strain to effectively maintain flank contact of the engaged threads in operation. Therefore, in order to ensure that the rings do not loosen in operation, portions of the threads are deformed with a special tool during assembly to eliminate back off. In extremely dynamic drilling conditions, however, the impact forces and vibrations can become so high that a small amount of back off can occur.
  • a second problem associated with the loosening of the threaded ring is due to the split nature of the rings. Because each ring half can move independently, even slight backing off of the threaded ring allows each half to slide radially until the roots and crests of the mating threads engage. This can cause the effective inside diameter of the paired ring halves to change by .030 inches or more and can drastically reduce the threaded ring's retention force or cause an unacceptable gap in a radial bearing member.
  • the present invention is a threaded ring bearing member for rolling cutter drill bits with at least a portion of its threads having a different pitch than its mating threads.
  • thread pitch is defined as the number of threads per unit of length.
  • the pitch difference is designed so that the threaded ring can be seated or otherwise located precisely with respect to the other bearing elements within the drill bit to effectively control the axial displacement of the rolling cutter on the bearing spindle within a given tolerance range.
  • the difference in thread pitch causes the opposite, opposing mating flanks to engage, effectively applying a tensile or compressive force to a portion of the threaded ring bearing member, which gradually increases as the assembly is tightened.
  • a rolling cutter drill bit comprising: a bit body, at least one bearing spindle on said bit body, a rolling cutter rotatably mounted on said bearing spindle, a first set of screw threads formed in one of said cutter or said bearing spindle, a portion of said first set of screw threads having a first thread pitch, a bearing mounted between said cutter and said bearing spindle, said bearing comprising a split threaded ring having a second set of screw threads, a portion of said second set of screw threads having a second thread pitch, said split threaded ring being in screw threaded engagement with one of said cutter or said bearing spindle, characterised in that said first thread pitch is different from said second thread pitch.
  • a portion of one of the screw-threads may be mechanically deformed by an implement after assembly to further improve resistance to back off of the threaded retention member.
  • Figure 1 is a perspective view of a rolling cutter drill bit of the present invention.
  • Figure 2 is a cross sectional view of one preferred embodiment of an earth boring bit of the present invention showing the general arrangement of the cutter's lubrication and bearing system.
  • Figure 2a is a perspective view of a threaded ring bearing of one embodiment of the present invention.
  • Figure 3 is an enlarged cross sectional view of the threads of the prior art threaded ring engaged in the threads of the rolling cutter.
  • Figure 4 is an enlarged cross sectional view of the threads of the prior art threaded ring engaged in the threads ofthe rolling cutter with the ring slightly loosened.
  • Figure 5 is an enlarged cross sectional view of the threads of the prior art threaded ring engaged in the threads of the rolling cutter with the ring slightly loosened showing a radial displacement caused by the further meshing of the loosened threads.
  • Figure 6 is an enlarged cross sectional view of the threads of the present invention.
  • Figure 7 is an enlarged cross sectional view of the threads of an alternative embodiment of the present invention.
  • Figure 8 is an enlarged cross sectional view of the threads of another embodiment of the present invention.
  • Figure 9 is an cross sectional view of the threads of the present invention used as a combination thrust and radial bearing.
  • a rolling cutter earth boring bit 10 includes a body 12 with three similar leg portions 14.
  • a cantilevered bearing spindle 16 formed on each leg 14 extends inwardly and downwardly.
  • a rolling cutter 18 is rotatably mounted upon each leg 14. Attached to the rolling cutter 18 are cutting inserts 20 which engage the earth to effect a drilling action and cause rotation of the rolling cutter 18.
  • each cutting insert 20 will be formed of hard, wear resistant material.
  • Internal passageways 22, 24 & 26, as well as a reservoir 28 and bearing area 30 of the leg 14, are filled with lubricant (not shown) during bit assembly. The lubricant helps reduce friction during bit operation and is retained within the cutter 18 by a dynamic seal 32.
  • a pressure balancing diaphragm 34 serves to equalize internal and external pressures.
  • One passageway 26 provides an access used in assembly of the bit.
  • the cutter 18 is mounted upon the cantilevered bearing spindle 16 formed on the leg 14.
  • a floating friction bearing member 36 is located between the spindle 16 and a mating bearing cavity 38 formed in the cutter 18.
  • An internal thread 40 is formed on the surface of an internal cavity of the cutter adjacent the bearing area 30, and a split externally threaded retaining ring 42 is positioned in a peripheral groove 44 on the spindle 16 and is threadedly engaged with the threads 40 on the cutter 18.
  • This threaded ring 42 is mounted coaxially with the cutter 18 and spindle 16, and retains the cutter 18 upon the spindle 16 by forming an interference with a flange 46 on the bearing spindle 16.
  • the dimensional characteristics of the threaded ring 42, the groove 44 in the spindle 16, and the cavity 38 in the cutter are such as to allow some axial displacement of the cutter 18 with respect to the spindle 16.
  • the threaded ring bearing 42 is formed of two similar halves 43, and is configured with a threaded surface on its outside diameter when the two halves are joined at assembly.
  • a threaded ring bearing 142 is shown in various forms of engagement with the cutter 118.
  • the ring 142 is shown made up tight with the cutter 118.
  • the threads 148 on the threaded ring 142 engage the threads 140 in the cutter 118 along the flanks 156 leaving relative large gaps 150 between the sets ofthreads due to normal machine thread practice.
  • threads 48 of the threaded ring bearing 42 are formed with a slightly different pitch than the threads 40 in the cutter 18.
  • thread pitch is defined as the number of threads per unit of length.
  • the thread pitch of the threaded ring bearing 42 is slightly greater than the thread pitch of the cutter threads 40.
  • the difference in pitch depends upon the engaged length of the threads, the thread form, and the amount of assembly torque desired. In most rolling cutter drill bits the difference in the thread pitch of the threaded bearing member 42 is between .05% and 5% of the thread pitch of the cutter threads 40.
  • the configuration of the threaded bearing 42 of Figure 6 is such that the engaged flanks 56 at opposite ends of the ring provide interference in the threads as the assembly is subjected to assembly torque.
  • the interference force acts on the flanks 56 in a manner that tends to push the threaded ring bearing 42 away from the cutter 18. This force, therefore pushes each half of the split pair of threaded rings together. Given sufficient assembly interference, even 10 or more degrees of back-off of this assembly will not allow these threaded ring bearings 42 to move radially by any appreciable amount.
  • FIG. 7 Another embodiment of the present invention is shown in Figure 7.
  • the threaded ring bearing 42 has thread sets 50, 52 and 54 spaced such that there are effectively three different thread pitches.
  • the operating principle is the same.
  • the flanks 56 at the opposite ends of the engaged threads act to provide interference in the same manner described above.
  • FIG 8. Still another embodiment of the present invention is shown in Figure 8.
  • the threaded ring bearing 42 has a small set of threads 66 which has a different thread pitch than the remaining threads 68. In this configuration all the interference is contained within the engaged flanks 56 of the small set of threads 66.
  • the operating principle is the same. When the two members are assembled, an assembly torque is reached which will remain essentially constant over a variable engagement distance. With this design it is possible to have the benefits of differentially pitch threads in a single threaded ring bearing design even though the total amount of thread engagement for different implementations may vary.
  • FIG. 9 A configuration for a threaded ring bearing 60 which provides both thrust and radial bearing functions is shown in Figure 9.
  • the threads 62 of the threaded ring bearing 60 engage the cutter threads 40 over a longer engaged length.
  • the difference in thread pitch for this bearing 60 would typically be much less than the pitch difference for the threaded ring bearings 42 shown in Figures 6, 7 and 8.
  • threaded rings are shown as having two segments, the rings may be constructed with more than two segments.
  • threads shown in the figures are typical straight machine screw threads, many other thread forms may be used, such as Acme type threads or tapered threads, without departing from the scope of the present invention.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
EP97308197A 1996-10-18 1997-10-16 Anneau de retenue pour molettes de coupe Expired - Lifetime EP0837215B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US2896496P 1996-10-18 1996-10-18
US28964P 1996-10-18
CA002243938A CA2243938C (fr) 1996-10-18 1998-07-28 Dispositif de retenue d'un trepan a molettes

Publications (3)

Publication Number Publication Date
EP0837215A2 true EP0837215A2 (fr) 1998-04-22
EP0837215A3 EP0837215A3 (fr) 1999-03-17
EP0837215B1 EP0837215B1 (fr) 2006-01-18

Family

ID=31979169

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97308197A Expired - Lifetime EP0837215B1 (fr) 1996-10-18 1997-10-16 Anneau de retenue pour molettes de coupe

Country Status (2)

Country Link
EP (1) EP0837215B1 (fr)
CA (1) CA2243938C (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105545208A (zh) * 2016-02-22 2016-05-04 成都优拓优联科技有限公司 一种具有紧密螺纹的锁环

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7975779B2 (en) 2008-09-25 2011-07-12 Baker Hughes Incorporated Threaded cone retention system for roller cone bits

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3971600A (en) 1975-07-28 1976-07-27 Reed Tool Company Drill bit
US3989315A (en) 1975-08-14 1976-11-02 Reed Tool Company Drill bit
US4236764A (en) 1977-10-28 1980-12-02 Hughes Tool Company Earth boring drill bit with snap ring cutter retention
US4865137A (en) 1986-08-13 1989-09-12 Drilex Systems, Inc. Drilling apparatus and cutter
US4911255A (en) 1989-02-21 1990-03-27 Reed Tool Company Means for retaining roller cutters on rotary drill bit
US4991671A (en) 1990-03-13 1991-02-12 Camco International Inc. Means for mounting a roller cutter on a drill bit
US5012701A (en) 1990-02-05 1991-05-07 Camco International Inc. Method of making a threaded retainer ring for a roller cutter on a drill bit
US5024539A (en) 1990-08-13 1991-06-18 Edward Vezirian Friction bearing and cone retention thrust system for a rock bit
US5383525A (en) 1992-08-26 1995-01-24 Camco International Inc. Threaded ring retention mechanism

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3971600A (en) 1975-07-28 1976-07-27 Reed Tool Company Drill bit
US3989315A (en) 1975-08-14 1976-11-02 Reed Tool Company Drill bit
US4236764A (en) 1977-10-28 1980-12-02 Hughes Tool Company Earth boring drill bit with snap ring cutter retention
US4865137A (en) 1986-08-13 1989-09-12 Drilex Systems, Inc. Drilling apparatus and cutter
US4911255A (en) 1989-02-21 1990-03-27 Reed Tool Company Means for retaining roller cutters on rotary drill bit
US5012701A (en) 1990-02-05 1991-05-07 Camco International Inc. Method of making a threaded retainer ring for a roller cutter on a drill bit
US4991671A (en) 1990-03-13 1991-02-12 Camco International Inc. Means for mounting a roller cutter on a drill bit
US5024539A (en) 1990-08-13 1991-06-18 Edward Vezirian Friction bearing and cone retention thrust system for a rock bit
US5383525A (en) 1992-08-26 1995-01-24 Camco International Inc. Threaded ring retention mechanism

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105545208A (zh) * 2016-02-22 2016-05-04 成都优拓优联科技有限公司 一种具有紧密螺纹的锁环

Also Published As

Publication number Publication date
EP0837215B1 (fr) 2006-01-18
CA2243938A1 (fr) 2000-01-28
EP0837215A3 (fr) 1999-03-17
CA2243938C (fr) 2006-08-29

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