CA1137072A - Oil well drilling bit - Google Patents
Oil well drilling bitInfo
- Publication number
- CA1137072A CA1137072A CA000348282A CA348282A CA1137072A CA 1137072 A CA1137072 A CA 1137072A CA 000348282 A CA000348282 A CA 000348282A CA 348282 A CA348282 A CA 348282A CA 1137072 A CA1137072 A CA 1137072A
- Authority
- CA
- Canada
- Prior art keywords
- cutting elements
- roller cutter
- cutter
- drill bit
- row
- 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
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- Earth Drilling (AREA)
Abstract
ABSTRACT OF THE INVENTION
An oil well drilling bit is disclosed of the type utilizing hard metal inserts in the rolling cutters wherein each row of inserts on each cutter is located thereon in a sinusoidal or varying pattern rather than the strictly circumferential pattern of the prior art.
An oil well drilling bit is disclosed of the type utilizing hard metal inserts in the rolling cutters wherein each row of inserts on each cutter is located thereon in a sinusoidal or varying pattern rather than the strictly circumferential pattern of the prior art.
Description
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OIL WELI. DRILL:[:NG BIT
BACKGROUND OF THE INVENTIO~
In the drilling of a borehole through the earth's crusts to penetrate oil or gas bearing formations several types of drill bits are utilized. One category of drill bits is that of the roll-ing cone or rolling cutter drill blt. Such a bit usually utilizes three of such rolling cone cutters rotatably mounted on downward extending journals each of which protrudes from one of three legs -~ L0 extending downwardly at the lower end of the bit body. In the , rolling cone bit category there axe basically two types of cutter constructions. The ~lrst type is the "milled tooth" bit wherein the conical cutters have prot2uding cutting elements or mllled teeth formed on the surface thereof from the same basic piece of blank ;~
stock as the cone. The second category o~ rolling cone drill bits involves the "insert" type of bits wherein the cones are made of , :
one material and have drilled recesses in the surfaces for receiving hard metal cutting elements termed inserts.
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Each type of ~olling cone drill bit has advanta~es and ~0 disadvantages. The milled tooth type of bit is advantageous in that broad flat sharpened tooth shapes can be formed on the cutters to provide a wide sharply penetrating cutting action on the bottom ~ hole. These broad flat sharp milled teeth are also tough and - fracture resistant since they are made out of the same tough alloy as the cone and are integral parts thereof. The disadvantage in the milled tooth cutter type of bit is that the teeth are .
particularly suscept1ble to wear from abrasion and erosion of the alloy in the extended tooth area.
: :3 0 ~ 3~
The second type of bit, the insert bit, offers the advantage of the hard -~
metal cutting elements or inserts which are tremendously resistant to such abrasive forces. Usually the inserts are made of a very hard material such as tungsten carbide sintered and compacted into a generally cylindrical-frusto conical shape. Holes are usu~ally bored into the conical cutter to receive the cylindrical end of the insert and the generally frusto conical portion of the insert protrudes From the cutter surface. The disadvantage of the inserttype bits is that the inserts generally are not as fracture resistant as the mil`led tooth cutting elements and therefore cannot be shaped as broad and flat and sharp as the milled teeth. Thus the bottom hole coverage and penetration rate of the insert is less desirable than that of the milled tooth although ~;the insert generally will wear many times longer than the milled tooth.
-- The conventional insert bits manufactured today generally utilize three rolling cones having circumferential rows of inserts securely attached to the cones by interference fit within the holes bored substantially perpendicular `::
to the surface of the cone. These conventional cutter cones have rows of inserts in circumferential rows around the conical surfaces of the conesO One of the problems incurred in this conventional insert pattern is that because of the deeply bored insert recesses in the conical surfaces a weakening of the cone structure is effected. This weakening must be offset bX a thickening of the cone resulting in a circumferential land passing around the cone in the area of the insert locations. This adds to the weight and reduces the effective size of the allowable bearing surface on which the cone is mounted. In additionto the problem of the weakening of the cone structure, which weakening is particularly susceptible to hoop stresses in the cone structure, the insert type constructionalso suffers from an effect known as tracking and gyration.
Tracking and the resulting gyration occurs because of the circumferential rows of inserts forming grooves in the rock face being drilled. These parallel grooves leave a raised ridge of rock material called a kerf. When this kerf ?
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OIL WELI. DRILL:[:NG BIT
BACKGROUND OF THE INVENTIO~
In the drilling of a borehole through the earth's crusts to penetrate oil or gas bearing formations several types of drill bits are utilized. One category of drill bits is that of the roll-ing cone or rolling cutter drill blt. Such a bit usually utilizes three of such rolling cone cutters rotatably mounted on downward extending journals each of which protrudes from one of three legs -~ L0 extending downwardly at the lower end of the bit body. In the , rolling cone bit category there axe basically two types of cutter constructions. The ~lrst type is the "milled tooth" bit wherein the conical cutters have prot2uding cutting elements or mllled teeth formed on the surface thereof from the same basic piece of blank ;~
stock as the cone. The second category o~ rolling cone drill bits involves the "insert" type of bits wherein the cones are made of , :
one material and have drilled recesses in the surfaces for receiving hard metal cutting elements termed inserts.
.
Each type of ~olling cone drill bit has advanta~es and ~0 disadvantages. The milled tooth type of bit is advantageous in that broad flat sharpened tooth shapes can be formed on the cutters to provide a wide sharply penetrating cutting action on the bottom ~ hole. These broad flat sharp milled teeth are also tough and - fracture resistant since they are made out of the same tough alloy as the cone and are integral parts thereof. The disadvantage in the milled tooth cutter type of bit is that the teeth are .
particularly suscept1ble to wear from abrasion and erosion of the alloy in the extended tooth area.
: :3 0 ~ 3~
The second type of bit, the insert bit, offers the advantage of the hard -~
metal cutting elements or inserts which are tremendously resistant to such abrasive forces. Usually the inserts are made of a very hard material such as tungsten carbide sintered and compacted into a generally cylindrical-frusto conical shape. Holes are usu~ally bored into the conical cutter to receive the cylindrical end of the insert and the generally frusto conical portion of the insert protrudes From the cutter surface. The disadvantage of the inserttype bits is that the inserts generally are not as fracture resistant as the mil`led tooth cutting elements and therefore cannot be shaped as broad and flat and sharp as the milled teeth. Thus the bottom hole coverage and penetration rate of the insert is less desirable than that of the milled tooth although ~;the insert generally will wear many times longer than the milled tooth.
-- The conventional insert bits manufactured today generally utilize three rolling cones having circumferential rows of inserts securely attached to the cones by interference fit within the holes bored substantially perpendicular `::
to the surface of the cone. These conventional cutter cones have rows of inserts in circumferential rows around the conical surfaces of the conesO One of the problems incurred in this conventional insert pattern is that because of the deeply bored insert recesses in the conical surfaces a weakening of the cone structure is effected. This weakening must be offset bX a thickening of the cone resulting in a circumferential land passing around the cone in the area of the insert locations. This adds to the weight and reduces the effective size of the allowable bearing surface on which the cone is mounted. In additionto the problem of the weakening of the cone structure, which weakening is particularly susceptible to hoop stresses in the cone structure, the insert type constructionalso suffers from an effect known as tracking and gyration.
Tracking and the resulting gyration occurs because of the circumferential rows of inserts forming grooves in the rock face being drilled. These parallel grooves leave a raised ridge of rock material called a kerf. When this kerf ?
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becomes high enough it causes these rows of inserts to track down grooves formerly cut by the other cutter inserts and results in the drill bit following a non-central axis of rotation. When the drill bit begins to track, the action is an orbital action termed "gyration" and is a destructive force on the drill bit. Likewiser the gyration effect reduces the cutting speed of the bi-t to a negligible amount. The kerf buildup even-tually contacts the non-cutting surfaces of the cones and totally stops any cutting action of the bit in the hole. Likewise~ the gyration forc s introduced are not those for which the bit is designed and as a result, unusual damage usually occurs to the inserts, the cones and the bearings.
SUMMARY OF THE INVENTION
~`~ The present invention overcomes these disadvantages by providing a drill bit cone structure having a unique insert -- pattern which reduces failures from hoop stresses on the cone structure and greatly prevents gyration and trackirg of the conical cutters of the drill bit. Briefly this pattern of . .
insert placement on the conical cutters is a series of non-linear circumferential bands of inserts on the cutter surfaces.
More particularly the invention in one aspect pertains to a rolling cutter for a tri-cone drill bit, which cutter comprises a generally conical cutter body having a conical surface adapted to carry protruding cutting elements thereon and which is further adapted to be rotated in close proximity to an underground formation borehole face. One or more non-gage circumferential insert rows on the cutter conlcal surface are arranged peripherally around the cu-tter body and a plurality of hard metal inserts are in at least one of the non-gage rows, the inserts being located in a staggered non-circular peripheral relationship in the rows.
- The invention also pertains to an oil well drill bit of ~ the type having one or more downwardly extending legs, each ' ~
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having a downward projecting bearing journal with a generally conical cutter rotatably mounted thereon. The improvement comprises each conical cut-ter having a gage row of inser-ted hard metal cutting elements pro-truding thererom and at least one non-gage row o inserted hard metal cutting elements protruding therefrom. At least one o the non gage rows o inserted hard me-tal cutting elements is in at least one of the cutters arranged in a staggered non-circular peripheral relationship arouncl the cutter.
In a urther embodlment the invention contemplates a :
tricone roller cutter drill bit or drilling a well bore which -~
comprises a bit body having a threaded pin at its upper end adapted to be detachably secured to drill pipe for rotating ;
the drill bit and three dependiny legs at its lower end with each leg being spaced from the other legs and having an inwardly extending bearing ~ournal, and a roller cutter mounted on each kearing journal. Each of the roller cu-tter comprises a generally frustoconical body, and a plurality of elongated cutting elements of a tungsten carbide material mounted on the roller cutter body with their longitudinal axes extending generally radially with respect to the roller cu-tter body. Each cutting element tapers toward its outer end to a tip engageable with the bottom of the well bore, and the cutting elements are arranged in a plurality of generally annular rows around the roller cutter bodyr one row being adjacent the base of the roller cutter body and constitu-t-ing a gage row and another row being between the gage row and - the apex of the roller cutter body and constituting an in-ter-mediate row. The cutting elements of the intermediate row are spaced at generally equal inter~als around the roller cutter body with each cutting element being offset from the cutting .~ elements adjacent thereto in the direction of the longitudinal ", ,~.
axis of the roller cu-tter body. The amount of offset between - ~37~
the longitudinal centerlines of adjacent cutting elements of the intermediate row is less than the width of the -tip of a cuttiny element. Thus, -the tips of the cutting elements o~ the inter-mediate row overlap each other when the roller cutter is viewed in longitudinal sec-tion, whereby, upon rota-tion o the drill bit, the cutting elements of the intermediate row engage the bottom of the well bore over a generally annuIar area having a thickness greater than the width of the tip of a cutting element for in-creased bottom hole coverage by the drill bit, with a resultant reduction of the tendency of the drill bit to gyrate.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross-sectional plan view of the three cutter cones of a drill bit which embody the present invention.
Figure 2 is a partial cross-sectional view OL a cutter cone illustrating the insert patterns of the present invention. ;
Figure 3 is a partial developed view of one of the cutter cones showing the positioning of the inserts on the cutter cone.
Figure 4 is a view similar to Figure 3 showing the position-ing of the inserts of a second embodiment of the drill bit.
DESCRIPTION OF THE PREFERRED E~BODIMENTS
Figure 1 is a typical cutter layou-t of -the three conical cutters of a rolling cone drill bit. Because the cutters are located in non-planar relationship the single dimensional layout of the cutter relationship necessaxily requires the distortional effects resulting from this projection. As a result one of the cones must be split in half as i]lustrated in order -to show the - intermeshing relationships of the inserts on one cone with thoseof the adjacent cones. In Fiyure 1 the three conical cutters 10, 11, and 12 are illustrated in schematic cross-sectional view.
Each cutter comprises a generally conical body 13 upon which are ~ ~ circumferentially located raised insert lands 14 which pass cir-.~ J
- cumferentially around the conical surface of cutter 10. A plur-ality of hard metal cutting elements 15 commonly termed insexts i~37~Z
are located in cylindrical bore~, 16 drilled into cone 10 per-pendicular to the surace of land 14. Inserts 15 are yenerally secured tightly in recesses 16 by means of an interference ~i-t.
The interference fit is achieved by boring holes 16 slightly smaller in diame-ter -than the diameter of the cylirldrical portion o~ inserts 15.
The present invention is distinc-tly illustrated in Figure 1 ~ ;~
by the offset pattern o~ inserts 15, 17 and 18 projecting upward-: ly from land 14. In conventional designs all of the inserts in ~.
a land 14 would be located basically on -the same circumferential circle on the cutter surface. In the present invention the inserts in the land 14 are located in different concentric cir-cum~eren-tial circles around the cutter. This new cut-ter profile having offset or staggered inserts allows a greater bo-ttom hole .~ coverage with the same number of inserts and greatly reduces the tendency of the cutters to engage in tracking. This reduction o the tracki.ng tendency serves to reduce bit gyration and orbital action oE -the bit in the bottom of the bore hole.
Figure 2 illustrates an overlapping cutter profile showiny 20. the positioning of all of the inserts on the diferent cutters o a single bit. The inserts 15a and 15b in Figure 2 represent those inserts of cutter 11. Inserts 25a and 25b are those of cutter 10 and inserts 35a and 35b are the inserts of cutter 12.
Inserts 45 are the inserts o cutters 10 and 11 and inserts 55 . are inserts on all three cutters. The inserts at 55 are normally ; termed gage row inserts.
~ Reerring to Figures 3 and 4 the staggered or offset inserts pattern may be seen more clearly. In Figure 3 a sinusoidal insert pattern is disclosed wherein the inserts have three basic locations along the land 14. Each insert is ofset approximately the same amount in a lateral direction from each adjacent insert .
and basically ends up with three closely associated rows of inserts 7~7Z
in the same land. This pattern differs from the normal widely spaced rows of inserts on the conven-tional cu-tters in that each insert row in a single land is primarily overlapping each adjacent row with only a slight amount of offset to one side or the other.
The amount of o~fset in -the land 14 has been exaggerated in order to more clearly portra~ the pattern of inserts. Likewise, the land has been flattened ou-~ to illustra-te the insert~pattern but because of the circular conical shape of the cutter land 14 would ;-normally no-t be a straight flat surface.
Figure 4 illustrates a second embodiment of the insert design wherein the land 14 contains only two insert locations each sli~ht-ly offset from the other and both overlapping each other sub-stantially.
Thus, the present invention discloses a ne~ drill bit cutter profile utilizing non-aligned cutter inserts in each insert land on each oE the conical cutters. The non-aligned or staggered inserts provide a better coverage of the bottom hole surface, prevent tracking of following inserts, and thus greatly reduce bit gyration and non-circular orbital motion. As a result, breakage of inserts, destruction of cut-ter structures, and bearing failure are greatly reduced without sacrificing the normal rate of penetration of the drill bit.
Although a specific preferred embodiment of the ~resent in-.
vention has been described in the detailed description above, the description is not intended to limit the invention to the part-icular forms of embodiments disclosed therein since they are to be recognized as illustrative rather than restrictive and it will be obvious to those skilled in the ar-t that the invention is not so limited. For instance, whereas the insert patterns as des-cribed and illustrated in Figures 3 and ~ are of the sinusoidal configura-tlon, it is clear that other offset or staggered patterns ': ~
~3~72:
~ ':
could also be utilized efficiently. Thus~ the invention is declared to cover all changes and modifications or the specific example of the invention herein disclosed for purposes of illustration which do not constitute departure from the spirit and scope of the invention.
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becomes high enough it causes these rows of inserts to track down grooves formerly cut by the other cutter inserts and results in the drill bit following a non-central axis of rotation. When the drill bit begins to track, the action is an orbital action termed "gyration" and is a destructive force on the drill bit. Likewiser the gyration effect reduces the cutting speed of the bi-t to a negligible amount. The kerf buildup even-tually contacts the non-cutting surfaces of the cones and totally stops any cutting action of the bit in the hole. Likewise~ the gyration forc s introduced are not those for which the bit is designed and as a result, unusual damage usually occurs to the inserts, the cones and the bearings.
SUMMARY OF THE INVENTION
~`~ The present invention overcomes these disadvantages by providing a drill bit cone structure having a unique insert -- pattern which reduces failures from hoop stresses on the cone structure and greatly prevents gyration and trackirg of the conical cutters of the drill bit. Briefly this pattern of . .
insert placement on the conical cutters is a series of non-linear circumferential bands of inserts on the cutter surfaces.
More particularly the invention in one aspect pertains to a rolling cutter for a tri-cone drill bit, which cutter comprises a generally conical cutter body having a conical surface adapted to carry protruding cutting elements thereon and which is further adapted to be rotated in close proximity to an underground formation borehole face. One or more non-gage circumferential insert rows on the cutter conlcal surface are arranged peripherally around the cu-tter body and a plurality of hard metal inserts are in at least one of the non-gage rows, the inserts being located in a staggered non-circular peripheral relationship in the rows.
- The invention also pertains to an oil well drill bit of ~ the type having one or more downwardly extending legs, each ' ~
~l~L3~6~7~
having a downward projecting bearing journal with a generally conical cutter rotatably mounted thereon. The improvement comprises each conical cut-ter having a gage row of inser-ted hard metal cutting elements pro-truding thererom and at least one non-gage row o inserted hard metal cutting elements protruding therefrom. At least one o the non gage rows o inserted hard me-tal cutting elements is in at least one of the cutters arranged in a staggered non-circular peripheral relationship arouncl the cutter.
In a urther embodlment the invention contemplates a :
tricone roller cutter drill bit or drilling a well bore which -~
comprises a bit body having a threaded pin at its upper end adapted to be detachably secured to drill pipe for rotating ;
the drill bit and three dependiny legs at its lower end with each leg being spaced from the other legs and having an inwardly extending bearing ~ournal, and a roller cutter mounted on each kearing journal. Each of the roller cu-tter comprises a generally frustoconical body, and a plurality of elongated cutting elements of a tungsten carbide material mounted on the roller cutter body with their longitudinal axes extending generally radially with respect to the roller cu-tter body. Each cutting element tapers toward its outer end to a tip engageable with the bottom of the well bore, and the cutting elements are arranged in a plurality of generally annular rows around the roller cutter bodyr one row being adjacent the base of the roller cutter body and constitu-t-ing a gage row and another row being between the gage row and - the apex of the roller cutter body and constituting an in-ter-mediate row. The cutting elements of the intermediate row are spaced at generally equal inter~als around the roller cutter body with each cutting element being offset from the cutting .~ elements adjacent thereto in the direction of the longitudinal ", ,~.
axis of the roller cu-tter body. The amount of offset between - ~37~
the longitudinal centerlines of adjacent cutting elements of the intermediate row is less than the width of the -tip of a cuttiny element. Thus, -the tips of the cutting elements o~ the inter-mediate row overlap each other when the roller cutter is viewed in longitudinal sec-tion, whereby, upon rota-tion o the drill bit, the cutting elements of the intermediate row engage the bottom of the well bore over a generally annuIar area having a thickness greater than the width of the tip of a cutting element for in-creased bottom hole coverage by the drill bit, with a resultant reduction of the tendency of the drill bit to gyrate.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross-sectional plan view of the three cutter cones of a drill bit which embody the present invention.
Figure 2 is a partial cross-sectional view OL a cutter cone illustrating the insert patterns of the present invention. ;
Figure 3 is a partial developed view of one of the cutter cones showing the positioning of the inserts on the cutter cone.
Figure 4 is a view similar to Figure 3 showing the position-ing of the inserts of a second embodiment of the drill bit.
DESCRIPTION OF THE PREFERRED E~BODIMENTS
Figure 1 is a typical cutter layou-t of -the three conical cutters of a rolling cone drill bit. Because the cutters are located in non-planar relationship the single dimensional layout of the cutter relationship necessaxily requires the distortional effects resulting from this projection. As a result one of the cones must be split in half as i]lustrated in order -to show the - intermeshing relationships of the inserts on one cone with thoseof the adjacent cones. In Fiyure 1 the three conical cutters 10, 11, and 12 are illustrated in schematic cross-sectional view.
Each cutter comprises a generally conical body 13 upon which are ~ ~ circumferentially located raised insert lands 14 which pass cir-.~ J
- cumferentially around the conical surface of cutter 10. A plur-ality of hard metal cutting elements 15 commonly termed insexts i~37~Z
are located in cylindrical bore~, 16 drilled into cone 10 per-pendicular to the surace of land 14. Inserts 15 are yenerally secured tightly in recesses 16 by means of an interference ~i-t.
The interference fit is achieved by boring holes 16 slightly smaller in diame-ter -than the diameter of the cylirldrical portion o~ inserts 15.
The present invention is distinc-tly illustrated in Figure 1 ~ ;~
by the offset pattern o~ inserts 15, 17 and 18 projecting upward-: ly from land 14. In conventional designs all of the inserts in ~.
a land 14 would be located basically on -the same circumferential circle on the cutter surface. In the present invention the inserts in the land 14 are located in different concentric cir-cum~eren-tial circles around the cutter. This new cut-ter profile having offset or staggered inserts allows a greater bo-ttom hole .~ coverage with the same number of inserts and greatly reduces the tendency of the cutters to engage in tracking. This reduction o the tracki.ng tendency serves to reduce bit gyration and orbital action oE -the bit in the bottom of the bore hole.
Figure 2 illustrates an overlapping cutter profile showiny 20. the positioning of all of the inserts on the diferent cutters o a single bit. The inserts 15a and 15b in Figure 2 represent those inserts of cutter 11. Inserts 25a and 25b are those of cutter 10 and inserts 35a and 35b are the inserts of cutter 12.
Inserts 45 are the inserts o cutters 10 and 11 and inserts 55 . are inserts on all three cutters. The inserts at 55 are normally ; termed gage row inserts.
~ Reerring to Figures 3 and 4 the staggered or offset inserts pattern may be seen more clearly. In Figure 3 a sinusoidal insert pattern is disclosed wherein the inserts have three basic locations along the land 14. Each insert is ofset approximately the same amount in a lateral direction from each adjacent insert .
and basically ends up with three closely associated rows of inserts 7~7Z
in the same land. This pattern differs from the normal widely spaced rows of inserts on the conven-tional cu-tters in that each insert row in a single land is primarily overlapping each adjacent row with only a slight amount of offset to one side or the other.
The amount of o~fset in -the land 14 has been exaggerated in order to more clearly portra~ the pattern of inserts. Likewise, the land has been flattened ou-~ to illustra-te the insert~pattern but because of the circular conical shape of the cutter land 14 would ;-normally no-t be a straight flat surface.
Figure 4 illustrates a second embodiment of the insert design wherein the land 14 contains only two insert locations each sli~ht-ly offset from the other and both overlapping each other sub-stantially.
Thus, the present invention discloses a ne~ drill bit cutter profile utilizing non-aligned cutter inserts in each insert land on each oE the conical cutters. The non-aligned or staggered inserts provide a better coverage of the bottom hole surface, prevent tracking of following inserts, and thus greatly reduce bit gyration and non-circular orbital motion. As a result, breakage of inserts, destruction of cut-ter structures, and bearing failure are greatly reduced without sacrificing the normal rate of penetration of the drill bit.
Although a specific preferred embodiment of the ~resent in-.
vention has been described in the detailed description above, the description is not intended to limit the invention to the part-icular forms of embodiments disclosed therein since they are to be recognized as illustrative rather than restrictive and it will be obvious to those skilled in the ar-t that the invention is not so limited. For instance, whereas the insert patterns as des-cribed and illustrated in Figures 3 and ~ are of the sinusoidal configura-tlon, it is clear that other offset or staggered patterns ': ~
~3~72:
~ ':
could also be utilized efficiently. Thus~ the invention is declared to cover all changes and modifications or the specific example of the invention herein disclosed for purposes of illustration which do not constitute departure from the spirit and scope of the invention.
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~, : . _.. , , .
- 8 - ~
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Claims (10)
1. In an oil well drilling bit for drilling bore holes through underground earth formations, said bit having one or more downwardly extending legs, each said leg having a downwardly extending bearing journal upon which is rotatably mounted a generally conical cutter; the improvement comprising:
each said cutter having a plurality of insert mounting lands circumferentially located thereon;
each said land containing a plurality of hard metal cutting elements embedded therein and projecting therefrom;
said land and said cutting elements extending periph-erally around said cutters; and said cutting elements in each said land being offset from each other in a non-circular circumferential arrangement around said cutter.
each said cutter having a plurality of insert mounting lands circumferentially located thereon;
each said land containing a plurality of hard metal cutting elements embedded therein and projecting therefrom;
said land and said cutting elements extending periph-erally around said cutters; and said cutting elements in each said land being offset from each other in a non-circular circumferential arrangement around said cutter.
2. A rolling cutter for a tri-cone drill bit, said cutter comprising:
a generally conical cutter body having a conical surface adapted to carry protruding cutting elements thereon and further adapted to be rotated in close proximity to an underground formation borehole face;
one or more non-gage circumferential insert rows on said cutter conical surface arranged peripherally around said cutter body; and a plurality of hard metal inserts in at least one of said non-gage rows, said inserts being located in a staggered non-circular peripheral relationship in said rows.
a generally conical cutter body having a conical surface adapted to carry protruding cutting elements thereon and further adapted to be rotated in close proximity to an underground formation borehole face;
one or more non-gage circumferential insert rows on said cutter conical surface arranged peripherally around said cutter body; and a plurality of hard metal inserts in at least one of said non-gage rows, said inserts being located in a staggered non-circular peripheral relationship in said rows.
3, In an oil well drill bit of the type having three downward extending legs, each having a downward projecting bearing journal with a generally conical cutter rotatably mounted thereon, the improvement comprising:
each said conical cutter having a gage row of inserted hard metal cutting elements protruding therefrom and at least one non-gage row of inserted hard metal cutting elements protruding therefrom; and, wherein at least one of said non-gage rows of inserted hard metal cutting elements in at least one of said cutters is arranged in a staggered non-circular peripheral relationship around said cutter.
each said conical cutter having a gage row of inserted hard metal cutting elements protruding therefrom and at least one non-gage row of inserted hard metal cutting elements protruding therefrom; and, wherein at least one of said non-gage rows of inserted hard metal cutting elements in at least one of said cutters is arranged in a staggered non-circular peripheral relationship around said cutter.
4. A tricone roller cutter drill bit for drilling a well bore comprising:
a bit body having a threaded pin at its upper end adapted to be detachably secured to drill pipe for rotating the drill bit and three depending legs at its lower end, each leg being spaced from the other legs and having an inwardly extending bearing journal, and a roller cutter mounted on each bearing journal, each roller cutter comprising:
a generally frustoconical body, and a plurality of elongated cutting elements of a tungsten carbide material mounted on the roller cutter body with their longitudinal axes extending generally radially with respect to the roller cutter body, each cutting element tapering toward its outer end to a tip engageable with the bottom of the well bore, the cutting elements being arranged in a plurality of generally annular rows around the roller cutter body, one row being adjacent the base of the roller cutter body and constituting a gage row and another row being between the gage row and the apex of the roller cutter body and constituting an intermediate row, the cutting elements of said intermediate row being spaced at generally equal intervals around the roller cutter body with each cutting element being offset from the cutting elements adjacent thereto in the direction of the longitudinal axis of the roller cutter body, the amount of offset between the longitudinal center-lines of adjacent cutting elements or the intermediate row being less than the width of the tip of a cutting element, the tips of the cutting elements of the intermediate row thus over-lapping each other when the roller cutter is viewed in longi-tudinal section, whereby, upon rotation of the drill bit, the cutting elements of the intermediate row engage the bottom of the well bore over a generally annular area having a thickness greater than the width of the tip of a cutting element for increased bottom hole coverage by the drill bit, with a resultant reduction of the tendency of the drill bit to gyrate.
a bit body having a threaded pin at its upper end adapted to be detachably secured to drill pipe for rotating the drill bit and three depending legs at its lower end, each leg being spaced from the other legs and having an inwardly extending bearing journal, and a roller cutter mounted on each bearing journal, each roller cutter comprising:
a generally frustoconical body, and a plurality of elongated cutting elements of a tungsten carbide material mounted on the roller cutter body with their longitudinal axes extending generally radially with respect to the roller cutter body, each cutting element tapering toward its outer end to a tip engageable with the bottom of the well bore, the cutting elements being arranged in a plurality of generally annular rows around the roller cutter body, one row being adjacent the base of the roller cutter body and constituting a gage row and another row being between the gage row and the apex of the roller cutter body and constituting an intermediate row, the cutting elements of said intermediate row being spaced at generally equal intervals around the roller cutter body with each cutting element being offset from the cutting elements adjacent thereto in the direction of the longitudinal axis of the roller cutter body, the amount of offset between the longitudinal center-lines of adjacent cutting elements or the intermediate row being less than the width of the tip of a cutting element, the tips of the cutting elements of the intermediate row thus over-lapping each other when the roller cutter is viewed in longi-tudinal section, whereby, upon rotation of the drill bit, the cutting elements of the intermediate row engage the bottom of the well bore over a generally annular area having a thickness greater than the width of the tip of a cutting element for increased bottom hole coverage by the drill bit, with a resultant reduction of the tendency of the drill bit to gyrate.
5. A tricone roller cutter drill bit as set forth in Claim 4 wherein the cutting elements of the intermediate row are of circular transverse section and have generally conical portions at their outer free ends.
6. A tricone roller cutter drill bit as set forth in Claim 4 wherein the amount of offset between the centerlines of adjacent cutting elements of the intermediate row is less than one-half the width of the tip of a cutting element.
7. A tricone roller cutter drill bit as set forth in Claim 4 wherein the centerlines of the cutting elements of the intermediate row lie on a generally sinusoidal line extending around the roller cutter body.
8. A tricone roller cutter drill bit as set forth in Claim 7 wherein each cutting element of the gage row is off-set from the cutting elements adjacent thereto in the direction of the longitudinal axis of the roller cutter body, with the centerlines of the cutting elements of the gage row lying on a generally sinusoidal line extending around the roller cutter body
9. A tricone roller cutter drill bit as set forth in Claim 7 wherein the roller cutter body has at least one generally annular land thereon, the land extending along a generally sinusoidal line around the roller cutter body, the cutting elements of the intermediate row being mounted on said land.
10. A tricone roller cutter drill bit as set forth in Claim 7 wherein at least three cutting elements are included in each cycle of the sinusoidal line.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US6226079A | 1979-07-30 | 1979-07-30 | |
| US062,260 | 1979-07-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1137072A true CA1137072A (en) | 1982-12-07 |
Family
ID=22041294
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000348282A Expired CA1137072A (en) | 1979-07-30 | 1980-03-24 | Oil well drilling bit |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1137072A (en) |
-
1980
- 1980-03-24 CA CA000348282A patent/CA1137072A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |