Note: Descriptions are shown in the official language in which they were submitted.
lZ4~9~9
I ~N EXPOSED POLYCRYSTALLINE DIAMOND
2 MOUNT~D IN A MATRIX BODY DRILL BIT
4 ~ACKGROUND OF THE INVENTION
6 l. Field of the Invention
8 The invention relates to field of earth boring tools,
9 and more particularly to diamond drill bits incorporating
synthetic diamond cutting elements~
11
12 2. Description of the Prior Art
13
14 The use of diamonds in drilling products is well known.
More recently synthetic diamonds both single crystal diamonds
16 (SCD) and polycrystalline diamonds (PCD) have become commercially
17 available from various sources and have been used in such
18 products, with recognized advantages. For example, natural
19 diamond bits effect drilling with a plowing action in comparison
to crushing in the case of a roller cone bit, whereas synthetic
21 diamonds tend to cut by a shearing action. In the case of rock
22 formations, for example, it is believed that less energy is
23 required to fail the rock in shear than in compression.
241
251 More recently, a variety of synthetic diamond products
26 ~ has become available commercially some of which are available as
227 I polycrystalline products. Crystalline diamonds preferentially
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1 fractures on (111), (110) and (100) planes whereas PCD tends to
2 be isotropic and exhibits this same cleavage but on a microscale
3 and therefore resists catastrophic large scale cleavage failure.
4 The result is a retained sharpness which appears to resist
polishing and aids in cutting. 5uch products are described, for
6 example, in U.S. Patents 3,913,280; 3,745,623; 3,816,085;
7 4,104,344 and 4,224,380.
9 In general, the PCD products are fabricated from
10 synthetic and/or appropriately sized natural diamond crystals
11 under heat and pressure and in the presence of a solvent/catalyst
12 to form the polycrystalline structure. In one form of product,
13 the polycrystalline structures includes sintering aid material
14 di tributed essentially in the interstices where adjacent
15 crystals have not bonded together.
16
17 In another form, as described for example in V. S.
18 Patents 3,745,623; 3,816,085; 3,913,280; and 4,224,380
19 the resulting diamond sintered product is porous, porosity being
20 achieved by dissolving out the nondiamond material or at least a
21 portion thereof, as disclosed for example, in U. S. 3,745,623;
22 4,104,344 and 4,224,380. For convenience, such a material may be
23 described as a porous PCD, as referenced in U.S. 4,224,380.
24
Polycrystalline diamonds have been used in drilling
26 products either as individual elements or as relatively thin PCD
27 tables supported on a cemented tungsten carbide (WC) support
28
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1 backings. In one form, the PCD compact is supported on a
2 cylindrical slug about 13.3 mm in diameter and about 3 mm long,
3 with a PCD table of about 0.5 to 0.6 mm in cross section on the
4 face of the cutter. In another version, a stud cutter, the PCD
table also is supported by a cylindrical substrate of tungsten
6 carbide of about 3 mm by 13.3 mm in diameter by 26mm in overall
7 length. These cylindrical PCD table faced cutters have been used
8 in drilling products intended to be used in soft to medium-hard
9 formations.
101
11 Individual PCD elements of various geometrical shapes
12 have been used as substitutes for natural diamonds in certain
13 applications on drilling products. However, certain problems
14 arose with PCD elements used as individual pieces of a given
carat size or weight. In general, natural diamond, available in
16 a wide variety of shapes and grades, was placed in predefined
17 locations in a mold, and production of the tool was completed by
18 various conventional techniques. The result is the formation of
19 a metal carbide matrix which holds the diamond in place, this
matrix sometimes being referred to as a crown, the latter
21 attached to a steel blank by a metallurgical and mechanical bond
22 formed during the process of forming the metal matrix. Natural
23 diamond is sufficiently thermally stable to withstand the heating
24 process in metal matrix formation.
26 In this procedure above described, the natural diamond
28 could be either surface-set in a predetermined orientation, or
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1 ¦ impregnated, i.e., diamond is distributed throughout the matrix
2 in grit or fine particle form.
4 With early PCD elements, problems arose in the
production of drilling products because PCD elements especially
6 PCD tables on carbide backing tended to be thermally unstable at
7 the temperature used in the furnacing of the metal matrix bit
8 crown, resulting in catastrophic failure of the PCD elements if
9 the same procedures as were used with natural diamonds were used
with them. It was believed that the catastrophic failure was due
11 to thermal stress crack~ from the expansion of residual metal or
12 metal alloy used as the sintering aid in the formation of the PCD
13 element.
14
Bra~ing techniques were used to ix the cylindrical PCD
16 table faced cutter into the matrix using temperature unstable PCD
17 products. Brazing materials and procedures were used to assure
18 that temperatures were not reached which would cause catastrophic
19 failure of the PCD element during the manufacture of the drilling
tool. The result was that sometimes ~he PCD components separated
21 from the metal matrix, thus adversely affecting performance of
22 the drilling tool.
23
24 With the advent of thermally stable PCD elements,
typically porous PCD material, it was believed that such elements
27 could be surface-set into the metal matrix much in the same
28 1 fashion as natural diamonds, thus simplifying the manufacturing
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1~ ~2~ 39
process f the ~ril1 too1, and providing better perform~nce due
2 1 to the fact that PCD elements were believed to have advantages of
3 less tendency to polish, and lack of extended inherently weak
4 cleavage planes as compared to natural diamond.
s
6 Significantly, the current literature relating to porous
7 PCD compacts suggests that the element be surface-set. The
8 porous PCD compacts, and those said to be temperature stable up
9 to about 1200 C are available in a variety of shapes, e.g.,
cylindrical and triangular. The triangular material typically is
11 about 0.3 carats in weight r measurès 4mm on a side and is about
12 2.6mm thick. It is suggested by the prior art that the
13 triangular porous PCD compact be surface-set on the face with a
14 minimal point exposure, i.e., less than 0.5mm above the adjacent
metal matrix face for rock drills. Larger one per carat
16 synthetic triangular diamonds have also become available,
17 measuring 6 mm on a side and 3.7 mm thick, but no recommendation
18 has been made as to the degree of exposure for such a diamond.
19 In the case of abrasive rock, it is suggested by the prior art
tha~ the triangular element be set completely below the metal
21 matrix. For soft nonabrasive rock, it is suggested by the prior
22 art that the triangular element be set in a radial orientation
23 with the base at about the level of the metal matrix. The degree
241 o?r ?r?rfexposure recommended thus depended on the type of rock
formation to be cut.
27 The difficulties with such placements are several. The
28~ -6-
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1 difficulties ~ay be understood by considering the dynamics of the
2 drilling operation. In the usual drilling operation, be it
3 mining, coring, or oil well drilling, a fluid such as water, air
4 or drilling mud is pumped through the center of the tool,
radially outwardly across the tool face, radially around the
6 outer surface (gage) and then back up the bore. The drilling
7 fluid clears the tool face of cuttings and to some extent cools
8 the cutter face. Where there is insufficient clearance between
9 the formation cut and the bit body, the cuttings may not be
cleared from the face, especially where the formation is soft
11 or sticky. Thus, if the clearance between the cutting
12 surface-formation interface and the tool body face is relatively
13 small and if no provision is made for chip clearance, there may
14 be bit clearing problems.
16 Other factors to be considered are the weight on the
17 drill bit, normally the weight of the drill string and
18 principally the weight of the drill collar, and the effect of the
l9 fluid which tends to lift the bit off the bottom. It has been
reported, for example, that the pressure beneath a diamond bit
21 may be as much as 1000 psi greater than ~he pressure above the
22 bit, resulting in a hydraulic lift, and in some cases the
23 hydraulic lift force exceeds 50~ of the applied load while
24 drilling.
26 One surprising observation made in drill bits having
28 surface-set thermally stable PCD elements is that even after
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1 sufficient exposure of the cutting face has been achieved, by
2 running the bit in the hole and after a fraction of the surface
3 of the metal matrix was abraded away, the rate of penetration
4 often decreases. Examination of the bit indicates unexpected
polishing of the PCD elements. Usually RO~ can be increased by
6 adding weight to the drill string or replacing the bit. Adding
7 weight to the drill string is generally objectionable because it
8 increases stress and wear on the drill rig. Further, tripping or
9 replacing the bit is expensive since the economics of drilling in
10¦ normal cases are expressed in cost per foot of penetration. The
11 1 cost calculation takes into account the bit cost plus the rig
12 cos~ including trip time and drilling time divided by the footage
13 ¦ drilled.
14 l
Clearly, it is desirable to provide a drilling tool
16 having thermally stable PCD elements and which can be
8 manufactured at reasonable costs and which will perform well in
terms of length of bit life and rate of penetration.
19
It is~also desirable to provide a drilling tool having
22 thermally stable PCD elements so located and positioned in the
face of ~he tool as to provide cutting without a long run-in
23 period, and one which provides a sufficient clearance between the
241 cutting elements and the formation for effective flow of drilling
25 1 fluid and for clearance of cuttings.
27 Initial run-in in PCD diamond bits often breaks off the
28 -8-
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1 tip or point of the triangular c~tter. Therefore, an extremely
2 large initial exposure is required for synthetic diamonds. To
3 accommodate expected wearing during drilling, to allow for tip
4 removal during run-in, and to provide flow clearance necessary,
substantial initial clearance is needed.
7 Still another advantage is the provision of a dri lling
8 tool in which thermally stable PCD elements of a defined
9 predetermined geometry are so positioned and supported in a metal
matrix as to be effectively locked into the matrix in order to
11 provide reasonably long life of the tooling by preventing loss of
12 PCD elements other than by normal wear.
13
14 It is also desirable to provide a drilling tool having
thermally stable PCD elements so affixed in the tool that it is
16 usable in specific formations without the necessity of
17 significantly increased drill string weight, bit ~orque, or
18 significant increases in drilling fluid flow or pressure, and
19 which will drill at a higher RQP than conventional bits under the
2~ e drill1ng conditions.
2245
227
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2 BRIEF SUMMARY OF THE INVENTION
4 The invention is a cutter in a drill bit made of matrix
material comprising a diamond body disposed in the matrix
6 material of the drill bit and exposed above the surface of the
7 drill bit. The diamond body has a predetermined geometric
8 configuration and is disposed in the matrix material in such a
9 fashio~ to establish at 1east two loccking points be~ween the
diamond body and the matrix material. The manner in which the
11 diamond body is disposed in the matrix material is dependent in
12 part on the geometry of the diamond body. In particular, the
13 diamond body is oriented in the matrix material so that at least
14 one surface or portion of a surface of the diamond body is
acutely inclined with respect to the normal to the surface of the
16 matrix material at the location of the diamond body. The matrix
17 material thus forms a locking wedge over the diamond body where
18 it is acutely inclined with respect to the normal to the matrix
l9 surface at the location of the diamond body on the bit.
21 The invention is illustrated below in a plurality of
22 geometric shapes including triangular prismatic shapes elements,
23 prismatic rectangular elements, cylindrical elements, ovulate
24 elements, and plate-like elements. In addition, the invention
can be incorporated in free-form shapes which incorporate a
26 negatively curved surface which produces a lip or pedestal
27 extending and disposed below the surface of the ~atrix material
28
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1 ¦ or the bit face. By virtue of the spaced-apart locking points
2 established on the diamond body and between the diamond body and
3 the matrix material, the diamond body is securely retained in the
4 drill bit while allowing substantial exposure of the diamond body
above the matrix surface of the drill bit.
7 These and other advantages of the invention and its
8 various embodiments are better understood by now considering the
following Figures wherein like elements are reference by like
¦ numerals
22
26
27
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1~ .
~ 33~
1 BRIEF DESCRIPTION OF THE DRAWINGS
3 Figure l is a pictorial perspective of a drill bit
4 incorporating diamond elements raised above the face of the
matrix surface.
7 Figure 2 is a perspective view of a triangular prismatic
8 element embedded according to the invention within $he matrix
9 body bit of Figure 1 while allowing substantial exposure upon the
10¦ surface of the bit.
111
12¦ Figure 3 is a perspective view of a cubic element
13 ¦ attached to a matrix body bit according to the invention.
14 l
15 ¦ Figure 4 is a perspective view of a right circular
16 ¦ cylinder embedded in a matrix.
17 l
18 ¦ Figure 5 is a perspective view of a triangular prismatic
19 ¦ element embedded in a generally axial orientation in the matrix
20 ¦ body bit.
21 l
22 ¦ Figure 6 is a generalized ovulate diamond body embedded
23 in a matrix bit according to the invention.
241
251 Figure 7 is a right circular disc embedded according to
276 the invention in a matrix body bit.
281 -12-
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1 ¦ Figure 8 is a right circular cylindrical diamond element
2 ¦ embedded in a generally tangential direction in a matrix body bit
3 ¦ according to the invention.
4 l
¦ Figure 9 is a triangular prismatic element embedded in a
61 generally tangential orientation.
71
8¦ Figure 10 is a generally rectangular prismatic element
9 embedded in a matrix body but in a generally tangential
orientation.
111
12 ¦ Figure 11 is a triangular plate like element embedded in
13 ¦ a matrix body bit according to the invention in a generally
14 ¦ tangential orientation.
15 l
16 ¦ Figure 12 is a trapezoidal prismatic diamond element
17 ¦ embedded in a matrix body bit in a generally tangential
18 ¦ orientation.
19 ~
201 Figure 13 is a trapezoidal prismatic element embedded in
21 ¦ a matrix body bit in a generally axial orientation with backing
22¦ or inclined support as shown in side view.
231
24 ¦ Figure 14 is a view of the trapezoidal prismatic element
shown in Figure 12.
26 !
27 I Figure 15 is a free form diamond body embedded in a
28
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1; matrix body bit according to the invention.
3 ¦ The invention as exemplified in these various
4 ¦ embodiments is better understood by now turning to the following
5 ¦ detailed description which should be considered in light of the
1 sbove dr ~ings.
~5
22
28 -14-
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1¦ DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
2 1
31 The invention is the embedding and interlocking of a hard
4 ¦ cutting element into a bit body. More particularly, the
5 ¦ invention comprises the embedding and interlocking of a
6 ¦ polycrystalline synthetic, diamond (PCD) element into a matrix
7 ¦ body bit such that the diamond element is ~ubstantially exposed
81 above the surface of the matrix. The embedment and interlocking
9¦ of the diamond element is provided in such a way, as described
10¦ in greater detail below that at least two locking points are
11¦ provided between the diamond element and the matrix by virtue of
12 ¦ the embedment and geometric configuration of the diamond element.
13¦ The locking points provide means of interlockin~ the diamond
14¦ element into the matrix in order to prevent movement or
15¦ dislodging of the diamond matrix therefrom in substantially any
16 ¦ direction including particularly the direction normal to the
17 ¦ surface of the matrix. The invention as it is exemplified in
18 1 various embodiments can better be understood by now considering
19 1 the illustrated embodiments as set forth in the figures described
20¦ above.
211
22¦ Figure 1 is a pictorial perspective of a matrix body drill
23 ¦ 17. Bit face 17 is characterised by a gage 19, shoulder portion
24 ¦ 21, flank 23, nose 25 and apex 27. These portions of bit face 17
25 are also provided wi~h conventional junk slot~ 29 and collectors
26 and waterways 31 in communication with an axial crowfoot (not
27 shown). Between waterways and collectors 31 are lands or pads 33
28 l
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1 in which a plurality of diamond elements 35 are disposed
2 according to the invention. The surface of lands 33 is defined
3 as the matrix surface and is generally planar in the localized
4 area of each diamond element 35.
6 Turn now to Figure 2 wherein a perspective view of a
7 triangular prismatic PCD element, generally denoted by reference
8 numeral 10 is illustrated. Element 10 is configured as a
9 triangular prism characterised by two opposing triangular end
faces 12, only one of which is shown in Figure 2, and three
11 adjacent rectangular sides 14, again only one of which is
12 illustrated in Figure 2. Element 10 is prismatic, meaning that
13 the shape of element 10 is generated by translating one
14 triangular end face 12 in a parallel linear direction as defined
by longitudinal axis 16. Such PCD elements are well known to the
16 art and are manufactured under the trademark ~GEOSET" by General
17 Electric Company.
18
19 According to the invention, element 10 is embedded in
and interlocked with matrix 18 of bit 11 of Figure 1. Contrary
21 to the teachings of the prior art, PCD element 10 is raised well
22 above surface 20 of matrix 18, typically by more than 30% of
23 height 22 of element 10. For example, in the case of a 2103
24 "GEOSET", which is in the form of an equilateral triangular
prismatic element, element 10 may be mounted within matrix 18
26 and raised above the surface by more than 0.068 inch (1.73 mm).
27 In such an instance, height 22 is 0.35 inch (5.20 mm). In
28
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1 ¦ In such an instance, height 22 is 0.35 inch (5.20 mm). In
2 ¦ general, regardless of geometry, according to the invention more
3 ¦ than one-third of the linear dimension which is approximately
4 ¦ perpendicular to the matrix surface is exposed.
6 ¦ Element 10 is mounted and interlocked in matrix 18 by
7 ¦ having one side 14 forming a base 14a opposing the dihedral angle
8 ¦ forming an apical idge 24. Base 14a is disposed wit~in matrix 18
9¦ below surface 20 by less than 30% of height 22, or in the case of
10¦ the example of a 2103 "GBOSET" by less than 0.061 inch (1.56 mm).
11¦ Apical ridge 24 forms the most outwardly extended portion of
12 ¦ element 10 and element 10 can be set on face 20 of the matrix bit
13 ¦ in any orientation as desired without departing from the scope of
14 ¦ the invention. For example, apical ridge 24 may be set lying in
15 ¦ a direction parallel to the angular advance of element 10 as
16 ¦ defined by the rotation of bit 11. This is termed a radial set
17 ¦ in the case of a triangular prismatic element. Alternatively,
18 ¦ apical ridge 24 may be set at right angles to the direction of
19 ¦ advance of element 10 as defined by the rotation of the bit.
20 ¦ This setting is then defined as a tangential setting. In both
21¦ cases longituidnal axis 16 of element 10 is oriented generally
221 parallel to surface 20 of matrix 18 at the point of attachment of
231 element 10 thereto.
241
25 ~ In any of these orientations, triangular prismatic
26 ¦ element 10 is locked within matrix 18 by at least two locking
27 ~ points 26, only one of which is illustrated in Figure 2. Locking
28
I -17-
~ 33~3 ~
l ¦ embedded below surface 20 into matrix material 18. In the case
2 ¦ of triangular prismatic element 10, locking point 26 is actually
3 ¦ an entire surface. The second locking point is a like portion of
4 ¦ the adjacent ~urface 14 (not shown in Figure 2) which two
5 ¦ surfaces join to form the dihedral angle defining the apical edge
6 ¦ 24 of element 10. Locking point 26 is thus in the embodiment of
7 ¦ Figure 2 an inclined surface portion below surface 20. Element
8 ¦ 10 is fabricated or molded into the matrix body bit by
9 ¦ conventional infiltration techniques. As a result, matrix
10 ¦ material 18 forms an innerlocking abutment against the sloped
11¦ surface of locking point 26 thereby providing a wedged shaped
12¦ lock on element 10. In other words, the embedded portions of
13¦ surfaces 14 are inclined away from the normal to surface 20 and
14¦ are spaced apart. Matrix material 18 forms integral overlying
15¦ wedges so that element 10 is locked into matrix 18 with respect
l6¦ to all directions~ That is, a force in any direction tending to
17¦ remove element 10 from surface 20 would be resisted by locking
18 points 26.
191
20 ¦ In the embodiment of Figure 2, it was assumed that end
21 ¦ surfaces 12 were perpendicular ~urfaces to longitudinal axis 16
22 and thus locking points 26 were formed only on opposing surfaces
23 14 below surface 20. However, it is entirely within the scope of
24 the invention that end surfaces 12 may be inclined with respect
to longitudinally axes 16 thereby providing two additional
26 spaced apart locking points, which together with locking points
28 26, would form two othogonal pairs of such locking points, or in
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1 the case of Figure 2 locking surface portions.
3Turn now to Figure 3 wherein the invention is
4 illustrated in the context of a rectangular prismatic element,
5 generally denoted by numeral 28. For convenience, rectangular
6 prismatic element 28 is shown as a cubic diamond element, which
7 may either be a natural cubic element or may be synthetically
8 manufactured. In either case, element 28 is disposed within
9 ¦ matrix material 18 below surface 20 in such a manner that at
10 ¦ least two locking points 30 and 32 are provided. Locking point
11 ¦30 is formed at one corner 34 of cubic element 28 while locking
12 ¦ point 32 is formed at the adjacent corners 36, one of which is
13 ¦illustrated in Figure 3. Element 28 is disposed within matrix 18
14 ¦ at an angle so that its normal axis of symmetry 38 is inclined
15 with respect to surface 20 at the point of attachment of element
16 ¦ 28 to the matrix bit. The inclination of axis 38 causes at least
17 ¦ one of the four basal corners, in this case corner 34, to be
18 ¦ cocked up at an angle so as to be disposed within matrix 18 at a
19 ¦ lesser depth than at least one other corner of cubic element 28.
20 ¦ In the most general case, the inclination of axis 38 is such that
21 ¦ no face of cubic element 28 is perpendicular to surface 20. In
22 ¦ the illustrated embodiment of Figure 3, the inclination of axis
231 3B causes corner 34 to be the highest corner followed by adjacent
241 corners 36 and lastly, by lowest opposing corner 40. The angular
251 orientation of axis 38 thus causes edge 42, which is adjacent to
26¦ corner 34, to be inclined upwardly through surface 20 of matrix
27 material 18 at an acute angle. Thus, matrix material 18 fills
28 l
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1248939
1 around corner 34 forming an overlying wedged mass which locks
2 corner 34 into the matrix of a bit and prevents movement of
3 element 28 in a normal direction at the point of attachment.
4 Thus, in the embodiment of Figure 3, locking point 30 at corner
34 is a surface portion in the proximity of corner 34 of adjacent
6 sides 44 which join together to form the dihedral angle 46 and
7 edge 42. In fact, locking points 30 and 32 are merged to
8 include lower surface portion of side 44 in the proximity of and
9 adjacent to basal edge 48 from corner 34 to adjacent corner 36.
In other words, if cube 28 were to be lifted in a perpendicular
11 direction from ~urface 20, matrix material 18 in contact with
12 locking point 30 between corners 34 and 36 of adjacent edge 48
13 and the adjacent symmetrically placed edge (not shown), provide a
14 locking surface which tends to retain cubic element 28 within
matrix material 18.
16
17 Clearly, the embedment of cubic element 28 within matrix
18 material 18 also provides a means of resisting any forces
19 imparted on element 28 in a direction parallel to surface 20.
Cubic element 28 is not locked into matrix 18 only in the
21 direction of axis 38. Resistance to these parallel or azimuthal
22 forces which may be applied to element 28 would also be provided
23 if axis of symmetry 38 were substantially perpendicular to
24 surface 20. However, in this last case, locking point 30 would
have disappeared and there would be no mechanical means, other
26 than cohesion, micromechanical attachment or other bonding
27 between element 28 and matrix material 18 which would retain or
28 20-
l ¦ lock element 28 in matrix material 18.
2 l
3 ¦ Turn now to Figure 4 wherein yet another embodiment of
4 ¦ the invention is illustrated. In the embodiment of Figure 4 a
51 right circular cylindrical element, generally denoted by
61 reference numeral 50, is illustrated. Cylindrical element 50 i9
7 ~ characterised by a longitudinal axis of symmetry 52. Element 50
8 ¦ is disposed within matrix 18 below surface 20 in such a manner
9¦ that axis 52 is inclined at an acute angle to surface 20. By
10¦ virtue of the angular orientation of cylindrical element ~0, a
ll¦ locking point or more strictly speaking, a plurality of locking
12¦ points are formed on the lower sùrface of element 50 in the
13¦ proximity of base 56. For convenience of illustration, base 56
14¦ is shown as a flat circular base while the opposing end of
15¦ cylindrical element 50 is illustrated as being generally domed.
16¦ Clearly, the shape of opposing end 58 can be arbitrarily chosen.
171
18¦ Because of the angular orientation of cylindrical
19 element 50, a locking point 54 is formed on an inclined surface
portion of cylindrical element below surface 20 of matrix 18.
21 Matrix material 18 is molded about the embedded portion of
22 cylindrical element 50 and thereby ~orms a locking wedge against
23 the acutely inclined surface portions. Thereby, by virtue of
24 this embedment, both azimuthal forces parallel the surface 20 and
normal foeces perpendicular to surface 20, are positively
2~1 resisted by a mechanical lock of elemen~ 50 within matrix
271 material 18.
281
l -21-
, I ~48g3~
1 Turn now to Figure 5 wherein yet another embodiment is
2 illustrated. Figure 5 shows a perspective view of a triangular
3 prismatic element 10 which was shown and described in connection
4 with Figure 2 disposed below surface 20 into matrix material 18
in such a manner that longitudinal axis 16 is acutely inclined
6 with respect to the normal to surface 20 rather than being
7 perpendicular thereto as shown in Figure 2. At least one corner
8 60 is thus defined as being the highest corner of element 10
9 which is embedded within matrix material 18. Adjacent corner 62
is disposed within matrix material 18 at a greater depth as
11 determined by the size of element 10 and the angular orientation
12 of longitudinal axis 16 with respect to the surface normal. At
13 least one locking point 64 and, in fact, a plurality of locking
14 points are then formed on that portion of side 14 disposed
beneath surface 20. In the case of the embodiment of Figure 5,
16 locking points 64 are formed on two adjacent sides 14 which join
17 together to form the dihedral edge 24. Matrix material 18 is
18 molded about surface 14 once again forming an overlying wedge
19 which locks element 10 onto surface 20 and which resists
substantially all forces which may be exerted upon element 10
21 which might tend to remove it from surface 20.
22
23 Whereas tbe embodiments of Figures 1-5 were triangular,
24 cubical or cylindrical, the embodiment of Pigure 6 has been
generali~ed ~o include an arbitrary ovulate diamona element,
26 generally denoted by reference numeral 66. In the illustrated
28 embodiment, ovulate element 66 is characterised by a major
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1 longitudinal axis 68 which defines a direction of preferential or
2 maximum elongation. The angular orientation of major axis 68 of
3 relements 66 is inclined sufficiently with respect to the normal
4 to surface 20 such that at least two locking points, again a
surface portion defining the plurality of locking points 70, are
6 defined below surface 20 on element 66. The curvature of ovulate
7 element 66 is such that it begins to fall away from the normal to
8 surface 20 as it approaches surface 20 from beneath. In other
9 words, matrix material 18 is molded thereover and thus again
forms a wedging mechanical lock to retain element 66 in matrix
11 material 18. A locking resisting force exist for all directions
12 except one, major axis 68.
13
14 The embodiments of Figures 2-6 described above are each
rgenerally characterised by a diamond element having a
16 longitudinal axis lying along a direction of major elongation of
17 the element or at least in a direction of equal elongation as in
18 t?r?rhe case of cubic element 28 in Figure 3. Turn now to Figure
19 7 wherein a right circular diamond disk, generally denoted by
reference numeral 72 is embedded within matrix material 18 and
21 exposed above surface 20 according to the invention. In the
22 illustrated embodiment 72 is characterised by an axis of symmetry
23 74. Axis 74 is again acutely aligned with respect to the normal
24 at surface 20 so that one edge 76 is well exposed above matrix
surface 20 while the diametrically opposing edge 78 is embedded
26 within matrix material 18 below surface 20. At least two locking
27 points, again a plurality of locking points 80, are formed at a
28
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I ~Z~8C~39
1 portion of the upper surface of àisk 72 in the proximity of edge
2 78 and below surface 20. In other words, disk 72 is embedded in
3 surface 20 of the matrix bit at an inclined angle such that the
4 leading edge is fully exposed while the trailing edge is fully
embedded with portions of the edges of disk 72 between diametric
6 points 76 and 78 either being exposed or embedded to lesser or
7 greater degrees depending on their proximity to diametrically
8 opposed points 76 and 78 respectively. Therefore, disk 72 is
9 securely locked within matrix 18 against bo'ch azimuthal forces
and normal forces to surface 20.
11
12 The invention is further illustrated in the embodiment
13 of Figure 8 wherein a right circular cylindrical element 50 as
14 described in connection with the embodiment of Figure 4 is
15 disposed into matrix 18 below surface 20. Again, the exposed end
16 58 of cylinder 50 is shown as having a domed shape purely for
17 convenience and not as a means of limiting the invention. The
18 opposing end or base 56 is disposed at least partially within
19 matrix ma~erial 18 so that at least two, and actually a plurality
20 of locking points 82, are formed thereon. In other words, at
21 least a portion of cylinder 50 is embedded deeply enough such tht
22 the diameter of a perpendicularly cross section to axis 52 is
23 below surface 20. Even in the case wherein a portion of base 56
24 may be exposed above surface 20, a plurality of locking points 82
25 are formed on that portion above centerline point 84 of base 56
26 which is disposed below surface 20. The surface of cylindrical
27 element 50 falls away at an acute angle from the normal to
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12~8939
1 surface 20 of matrix material 18 as surface 20 i5 approached.
2 Thus, matrix material 18 is molded over the locking points 82 on
3 cylindrical surface 50 and forms a locking wedge thereby
4 retaining element 50 within matrix material 18.
6 The invention is illustrated still further in the
7 embodiment of Figure 9. Turn now to Figure 9 wherein a
8 triangular prismatic element, generally denoted by reference
9 numeral 86, is disposed below surface 20 in matrix material 18 so
that a plurality of locking points 88 are formed on its surface.
11 Element 86 is similar to that described in connection with
12 Figures 2 and 5, with the exception that element 86 has been
13 elongated along longitudinal axis 90. ~owever, the embodiment of
14 Figure 9 should be interpreted to include element 10 of Figures 2
and 5 as well. Like the cylindrical embodiment of Figure 7,
16 triangular element 86 of Figure 8 includes at least a portion
17 embedded below surface 20 of matrix 18. At each point on the
18 embedded portion of side 92, the slope of side 92 falls away from
19 the normal to surface 20 as surface 20 is approached from below.
Again, matrix material 18 is molded over side 92 thereby forming
21 a wedge-shaped lock ovee the embedded portion of side 92 and
22 thus, the plurality of locking points 88. Meanwhile, a
23 substantial forward portion of element 86 is completely exposed
24 above surface 20 of matrix 18. In fact, it is not necessary that
trailing corner 94 be flush with surface 20 as illustrated in
26 Figure 9. Instead, trailing corner 94 may be disposed well above
27 surface 20 as well, locking points 88 remain established as long
28
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1 ¦ as any portion of adjacent sides 92 remain disposed below surface
2 20 into matrlx 18.
4 Turn now to Figure 10 wherein yet another embodiment is
illustrated showing an elongated rectangular pri~matic element,
6 generally denoted by reference numeral 96. In the illustrated
7 embodiment of Figure 9, element 96 is embedded below surface 20
8 into matrix 18 with opposing sides 98 generally parallel to the
9 normal to surface 20. However, one end surface 100 is
substantially or fully exposed above surface 20 while the
11 opposing end surface 102, only the edge of which is shown in
12 Figure 10, is disposed beneath surface 20. Thus, matrix material
13 18 is disposed over at least a portion of one `end of element 96
14 and forms a plurality of locking points 104. A wedged-shape
extension of matrix 18 is integrally formed over submerged end
16 102 thus providing the mechanical locking which prevents any
17 substantial dislodgment of element 96 from surface 20. ~gain,
18 element 96 has been shown as having a substantially elongated
19 longitudinal axis 106, although it must be understood that the
proportions of element 96 are arbitrarily fixed and could be
21 chosen to include the embodiment of Figure 3, which is cubic, as
22 well.
23
24 The invention continues to be illustrated in the
embodiment of Figure 11 wherein a flat triangular element,
26 generally denoted by reference numeral 108, is shown in
28 perspective view disposed within matrix 18. Triangular element
-~6-
11 lZ~893~
1 08 is character iaed by a longi~:udinal .IXiS 110 in a direction
2 normal to parallel and opposing end faces 112. The thickness of
3 element 108 or the distance between opposing end faces 112 is
4 smaller than the distance of the sides or height of triangular
element 108 thereby resulting in a flat plate-like triangular
6 element. According to the invention, element 108 is
7 substantially exposed above surface 20 of matrix 18 and locked
8 therein by a plurality of locking points 114. Locking points 114
9 are formed on a lower portion of end surface 112 which is
disposed below surface 20 by virtue of the acute angular
11 orientation of element 108 and its longitudinal axis 110 from the
12 normal. Matrix material 18 forms an integral edge over this
13 lower portion of element 108 thus defining and forming locking
14 points 114.
16 Turn now to the embodiment of Figure 12 wherein a
17 trapezoidal prismatic element, generally denoted by reference
18 numeral 116, is ~hown in perspective view as embedded below
19 surface 20. Element 116 includes at least two opposing parallel
surfaces 118, the upper of whicn is shown in the view of Figure
21 12. Between opposing parallel surfaces 118 are four sides
22 forming two opposing pairs, 120 and 122, at least one of which
23 pairs 120 has a trapezoidal shape. In the illustrated embodiment
24 of Figure 2, ~ide 120, is trapezoidal, while side 122 is
generally rectangular as would be produced by truncating the
26 triangular prismatic element 10 of Figure 2 along a plane
27 parallel to base 14a. Therefore, in the embodiment of Figure 12
2~
_2?-
~Z~939
1 a plurality of locking points 124 are formed along lower edge of
2 sides 122 in the same manner as locking points 26 are formed in3 the embodiment of Figure 2 with respect to element 10. Thus,
4 element 116 is locked within the matrix 18 in substantially the
same manner.
7 Turn now, however, to the embodiment of the invention as
8 illustrated in Figures 13 and 14 wherein a trapezoidal prismatic
9 element 126 is shown as embedded in an inclined orientation in
the matrix 18 and is locked therein by having portions below
11 surface 20. More particularly, element 126 is shown in the
12 illustrated embodiment of Figures 12 and 13 as fully trapezoidal
13 in the sense that parallel rectangular faces 128 are connected by
14 four adjacent trapezoidal-shaped faces formed in opposing pairs,
namely surfaces 130 and 132. However, it must be expressly
16 understood that the somewhat simpler trapezoidal element 116 of
17 Fi~ure 12 could be employed with appropriate modifications
18 according to the invention in a substantially similar embodiment
19 to that shown and descrlbed in connection with Figures 13 and 14.
21 With continued reference to Figures 13 and 14, element
22 126 is disposed within an inclined portion 134 of matrix material
23 18 which portion 134 of matrix material 18 forms an inclined
24 slope or support into which element 126 is embedded and locked.
The embodiments of Figures 13 and 14 incorporate the concept of
26 an inclined land on the bit face. Supported cutter or tooth
27 structures are distinguishable and are better shown in the
28
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~Z~g39
1 following pate~ts assigned to the same assignee of the
2 present invention:
3 TITLE ISSUE DATE PATENT NuMsER
4 TOOTH CONIFIGURATION FOR
EARTH BORING BIT Feb. 19, 1985 4,499,959
6 CUTTER CONFIGURATION FOR A
7 GAGE-To-sHouLDER TRANSITION May 6, 1986 4,586,574
8 DIAMOND ROTATING BIT
9 Nov. 5, 1985 4,550,790
11 In the illustrated embodiment, one end ~urface 132 as
12 shown in Figures 13 and 14 is fully exposed and is generally
13 coplanar with surface 20. In addition thereto, the upper
14 parallel rectangular side 128 is fully exposed as well. However,
each of the three remaining side surfaces 130 and the opposing
16 end surface 132 are embedded within matrix 18 below surface 20.
17 On each of these embedded surfaces a plurality of locking points
18 136 are thus formed by the integral extension of matrix 18 over
19 underlying sides 130 and 132. Thus, at least along sides 130 and
possibly along opposing lower side 132 depending upon the angular
21 orientation of element 126 with respect to the local surface
22 normal, a plurality of locking points 136 are defined and
23 established which will prevent the movement of element 126 not
24 only in any azimuthal direction across surface 20, but in the
vertical direction as well.
26
27 The embodiments thus described in connection with
28
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~24~3~39
1 Figures 1-14 have been described in each case in connection with
2 a regular geometric shape. Clearly, the invention could be
3 employed with many other geometric shapes other than those shown
4 and described according to the teachings set forth. For example,
in addition to regular geometric shapes, specialized or free-form
6 shapes can also be beneficially exploited to expose a diamond
7 cutting element above a matrix face. Turn now to Figure 15 for
8 one such embodiment. Figure 15 illustrates a perspective view of
9 a curvalinear, free-form synthetic diamond element generally
denoted by reference numeral 138. Element 138 in the illustrated
11 embodiment is shown as having an elongated body characterised by
12 a smooth apical surface 140 and a rounded nose portion 142 which
13 may be oriented in the direction of cutting as defined by
14 rotation of the drill bit. From apical surface 140, the sides of
element 138 sloped downwardly and are flared outwardly to form a
16 generally flat basal surface 144 and a peripheral lip 146. $he
17 surface adjoining the sides of element 138 with lip 146 are thus
18 characterised by a negative curvature evidenced through segment
19 148. E~ement 138 is therefore disposed within matrix 18 below
surface 20 so that lip 146 is substantially or fully embedded
21 therein, including at least a portion of the negatively curved
22 surface 148. Matrix material 18 is therefore molded about and
23 above lip 146, which forms a pedestal embedded into matrix 18.
241 The remaining portion of diamond element 138 is fully exposed
25 ¦ above matrix surface 20. Therefore, along the entire periphery
26 ¦ of lip 146, a plurality of locking points 150 are defined and
28 established which provide a means of mechanically locking diamond
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3~
1 element 138 onto and below surface 20. Clearly, many other
2 free-form shapes other than that one which is arbitrarily chosen
3 here to illustrate the invention in the embodiment of Figure 15
4 could be devised as well without departing from the teaching of
6 the invention.
7 Many modifications and alterations may be made by those
8 having ordinary skill in the art without departing from the
9 teachings of the invention as set forth herein. The illustrated
embodiments have been chosen only as a means of example and
11 should not be taken as limiting the scope of the invention which
l2 ls defi in the following clai=s.
2223
224
26
27
28
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