Hydraulic energy drill bit

A drill bit for drilling a rock foundation is provided having a bit face matrix for supporting a plurality of cutters, the matrix having one or more fluid passages for discharging a fluid to flow over the bit face. To enhance the cleaning and cooling of the plurality of cutters, the bit face matrix includes a nozzle for restricting the surface fluid flow area between the foundation and the bit face to create a high velocity radial fluid flow across the entire surface area of the bit face matrix. This fluid flow prevents debris from accumulating on the plurality of cutters thus providing cooling thereof. In addition, improved fluid distribution is provided by a spiraling dams structure extending from the nozzle radially outward over substantially the entire bit face matrix. This structure enhances the flushing of the debris from the bit face by accelerating the debris and drilling fluid to the outer diameter of the bit.

TECHNICAL FIELD 
The present invention relates to drill bits and more particularly, to a 
drill bit having a nozzle to provide a high velocity radial fluid flow 
across the surface of the bit for cleaning and cooling of the bit surface 
area during use. 
BACKGROUND ART 
Drill bits having a bit face supporting a plurality of synthetic diamond 
cutters are well known. These bits cut by scraping across a formation, 
thereby causing the rock to fail due to shear forces. In order to evacuate 
the debris broken up by the bit, a stream of drilling mud is directed 
downwardly through the drill bit and against the bottom of the formation. 
Prior art bits have also included grooves or recesses in the bit face to 
help effectuate the evacuation of debris. Although these structures have 
proven reasonably effective, they do not prevent the clogging of debris 
around the synthetic diamond cutters, especially those cutters near the 
outer periphery of the bit. When debris is not cleaned away from the 
surfaces of the cutters, the wear of the bit is increased. This problem is 
especially acute in drilling soft plastic formations, since cleaning these 
sticky formations from under the bit is extremely difficult. Further, 
although cleaning is not a problem when drilling in hard formations, 
during such drilling the cutters are subjected to high frictional heat. 
Therefore, there is a need for an improved drill bit structure that 
enhances the cleaning and cooling of the surface bit area. 
SUMMARY OF THE INVENTION 
A drill bit is provided comprising a bit face matrix having a plurality of 
synthetic diamond cutters mounted thereon. In accordance with the present 
invention, the cleaning and cooling of the bit surface area surrounding 
the synthetic diamond cutters is enhanced. More specifically, the bit 
includes a nozzle for restricting the surface fluid flow area between the 
foundation and the bit face matrix to create a high velocity radial fluid 
flow across the entire surface area of the bit face matrix. This fluid 
flow cleans the bit surface area by removing debris that could otherwise 
collect around the diamond cutter surfaces. In the preferred embodiment, 
the nozzle is formed by shaping the crest of the drill bit matrix in the 
form of a ring. In addition, the bit face matrix may include a spiraling 
dams structure in conjunction with the nozzle for providing better fluid 
distribution across the entire bit face. The spiraling dams structure 
serves to accelerate debris and drilling fluid to the outer diameter of 
the bit.

DETAILED DESCRIPTION 
With reference to FIG. 1, a plan view of the preferred structure of the 
improved drill bit 10 of the present invention is shown. Viewing the bit 
from the bit center 12 and moving radially outward, a "crow foot" fluid 
passage 14 is provided from which the drilling mud exits. The crest of the 
bit is shaped in the form of a ring to produce a ring or radius nozzle 16 
that imparts a high velocity to the drilling mud flowing past the face of 
the bit, as will be described in more detail below. Adjacent the ring or 
radius nozzle 16, there is shown a spiraling dam structure 18 for 
improving fluid distribution across the bit face. The spiraling dam 
structure 18 includes a plurality of identical abutting sections 18a-f. A 
plurality of junk slots 20 are provided on the outer diameter 22 of the 
bit 10 for removal of debris. Groups of small diamonds 24 are also 
provided for gauge protection of the outer diameter. A secondary water 
course 26 is provided adjacent to each group of diamonds 24 for cleaning 
thereof. It should be noted that FIG. 1 discloses the drill bit of the 
present invention with the plurality of synthetic diamond cutters removed. 
Also, although a "crow foot" fluid passage 14 is shown, those skilled in 
the art will appreciate that other types of fluid passages, such as a 
standard rock bit nozzle, can be utilized. 
FIG. 2 shows a projection of FIG. 1 including both a side view and a 
cutaway view of the drill bit 10 of the present invention. In FIGS. 1 and 
2, like numerals are used for corresponding elements. Referring first to 
the side view, a full view of a junk slot 20, a diamond grouping 24, and a 
secondary water course 26 is shown. These structures are well known in the 
prior art. The side view also discloses a spiraling dam section 18a that 
extends from the ring or radius nozzle 16 radially outward until a change 
in the bit contour of the bit face. Thus, the ring or radius nozzle 16 is 
located intermediate fluid passage 14 and the spiraling dam structure 18. 
The cutaway view of FIG. 2 shows details of the interior of the drill bit 
10. In particular, the bit 10 comprises a shank portion 32 formed of 
steel. The bit face 34 of the bit 10 is formed over the shank 32 and 
preferably is a tungsten carbide matrix. The cutaway view shows a flow 
passage 36 that connects the fluid passage 14 to a main bore 38. As 
drilling mud is pumped to the face of the bit through bore 38, flow 
passage 36 and out fluid passage 14, it is forced past the ring nozzle 16 
to produce a high velocity stream, as will be described below. This high 
velocity stream aids in flushing debris off of the drill bit face. As in 
FIG. 1, FIG. 2 does not disclose the placement of the plurality of 
synthetic diamond cutters. 
FIGS. 3 and 4 show a fragmentary plan view and a projection respectively of 
one of the dam sections 18a after the cutters have been mounted. Referring 
to FIGS. 3 and 4, a plurality of synthetic diamond cutters 40-52 are 
provided on the bit face matrix. FIG. 3 shows the preferred locations of 
the synthetic diamond cutters 40-52 relative to the bit center 12, the 
nozzle 16, the dam section 18a, and the bit outer diameter 22. More 
specifically, diamond cutters 40 and 42 are located within the ring nozzle 
16. Diamond cutters 44, 46, and 48 are mounted on the spiraling dam 
section 18a. Diamond cutters 50 and 52 are located near the outer diameter 
22 of the bit 10. As best seen in FIG. 4, each section of the spiraling 
dams structure 18 comprises a dam 54 and a connecting face 56 that 
connects the dam to a dam in the next abutting section. Each dam comprises 
approximately one-half of the sectioned area. 
In accordance with the present invention, synthetic diamond cutters 40-52 
comprise a wafer or plate of diamond bonded to a base material, preferably 
a tungsten carbide slug. These cutters were developed by General Electric 
Company and are commercially available under the trademarks STRATAPAX and 
COMPAX. The diamond wafer or plate is approximately 0.020 inches thick and 
0.52 inches in diameter. The diamond is not a single crystal but rather a 
diamond-to-diamond, bonded, polycrystalline material. The diamond plate, 
bonded to a tungsten carbide slug having a conical base, is inserted in 
the drill bit face so that the diamond plate protrudes therefrom at the 
proper angle for cutting rock. Typically, the diamond cutters are mounted 
by press fitting the slugs into holes on the bit face. The cutters can 
also be attached by a stud, or by a direct brazing process onto a platform 
or carrier on the bit face matrix. It should be appreciated that, although 
STRATAPAX and COMPAX diamond cutters are preferred, other types of 
synthetic diamond cutters may also be used in the present invention. 
Referring again to FIGS. 3 and 4, the operation of the present invention 
will now be described in detail. As the drill bit 10 rotates 
counterclockwise, the plurality of synthetic diamond cutters 40-52 cut the 
foundation by shearing the rock. The cut debris, in the form of 
appreciable size chips, is then removed from the drilled hole. In 
particular, drilling mud flows out of the fluid passage 14 to remove the 
cuttings from beneath the bit, these cuttings being accommodated by the 
junk slots 20. In prior drill bits the drilling mud exits one or more 
fluid passages, which may be of the "crow foot" type, and flows 
perpendicular to the horizontal bit axis; i.e., straight down toward the 
rock formation. This perpendicular flow is effective for removing debris 
from the synthetic diamond cutters nearest the location of the fluid 
passages. However, those diamond cutters located away from the fluid 
passage(s), i.e., the cutters on the outer periphery of the bit face when 
a "crow foot" passage is used, are typically not cleaned or cooled. This 
is because prior art designs don't adequately distribute the drilling mud 
over the entire bit face area. Cleaning of the cutters is especially 
difficult when drilling in soft or plastic formations. Further, although 
cleaning is not a problem when hard formations are drilled, the cutters 
are still subjected to high frictional heat, and thus require cooling. If 
the cutters are not cleaned and/or cooled, thermal damage may occur. 
The preferred structure of the instant invention comprising the ring nozzle 
16 and the spiraling dams structure 18 ameliorates the cleaning and 
cooling of the surface of the bit 10. In particular, as the drilling mud 
exits the fluid passage 14 the ring nozzle 16 restricts the surface fluid 
flow area between the rock foundation and the bit face matrix to create a 
high velocity radial fluid flow rather than a localized perpendicular flow 
relative to the horizontal bit axis. This high velocity is created due to 
the back pressure formed by the reduced flow area as best seen in FIG. 5 
to be described below. The high velocity radial flow of the drilling mud 
provides greater hydraulic energy cleaning potential as compared with 
prior art structures such that debris does not accumulate even on the 
diamond cutters located on the outer periphery of the bit. 
Fluid distribution across the bit face is enhanced by the spiraling dams 
structure 18 that extends from the ring nozzle 16 radially outward until a 
change in the bit contour. In operation, as fluid is ejected through the 
fluid passage 14 and across the nozzle 16, it is accelerated by the 
spiraling dam structure 18 as the bit rotates. More specifically, as fluid 
strikes the dams it is slung to the outside of the bit carrying debris as 
it moves. The spiraling dam structure 18 thus directs fluid across the 
entire bit face matrix to prevent debris from being accumulated on the 
synthetic diamond cutters 40-52. 
Referring to FIG. 2, it can be seen that the height of the nozzle 16 is the 
same as the dam heights from the top of the nozzle out until the dams are 
truncated. The height of the nozzle should be between 1/16th of an inch to 
approximately one inch. When the lower limit is used, only slight 
acceleration of fluid is achieved and cleaning may be ineffective. In 
contradistinction, with the nozzle height near the upper limit, a very 
large flow restriction would occur, thus preventing enough fluid from 
flowing to keep the diamond cutters cool. In the preferred embodiment, the 
optimum nozzle height should fall between 1/8 to 1/2 inch. However, as the 
diamond cutter shapes and dimensions change, the nozzle height must also 
be varied accordingly. It should also be recognized that both the nozzle 
radius and the nozzle location can be varied. Further, multiple nozzles, 
for example a number of concentric rings across the bit face matrix, can 
be utilized. 
Referring now to FIG. 5, an alternate embodiment of the drill bit is shown 
wherein the height of the dam 54 and the nozzle 16 are not the same. FIG. 
5 shows a profile of the cut formed in one bit revolution by the cutters, 
only cutters 60-63 are shown. Note that FIG. 5 also shows how the nozzle 
creates the high velocity radial fluid flow. In particular, the nozzle 
forms a reduced cross-sectional area 64 with respect to the rock formation 
65. The high velocity is created due to the back pressure formed by this 
reduced flow area. 
As noted above, a nozzle is formed whenever the surface fluid flow area 
between the rock formation and the bit fact matrix is restricted. 
Utilizing this fact, it can be seen that a nozzle is formed where 
different size synthetic diamond cutters are utilized. With reference to 
FIG. 6, diamond cutters 66 and 68 of varying diameters are provided. When 
such diamond cutters are mounted in close proximity to each other, a 
reduced cross sectional fluid flow area is formed to restrict fluid flow 
between the formation and the bit face. This restriction creates a back 
pressure that increases radial fluid velocity. 
An alternate embodiment of the nozzle structure is seen in FIG. 7. In 
particular, the nozzle has an inverted step 72 such that a diamond cutter 
74 is mounted lower than a diamond cutter 76 on the adjacent dam. This 
structure will also create a fluid flow restriction, thereby increasing 
fluid velocity. 
A drill bit utilizing hydraulic energy for cleaning and cooling the bit 
face thereof has been provided as described above. In accordance with the 
instant invention, a ring nozzle is formed in the bit face matrix to 
restrict the surface fluid flow area between the rock foundation and the 
bit face matrix to impart a high velocity to the drilling mud flowing past 
the face of the bit. As drilling mud is pumped to the face of the bit, it 
is forced past the ring nozzle in a high velocity radial stream. This high 
velocity stream aids in flushing debris from the plurality of synthetic 
diamond cutters implanted into the bit face matrix, thus keeping the 
cutters cool. Fluid distribution across the drill bit matrix is improved 
by providing a spiraling dams structure that extends radially outward from 
the ring nozzle. As the drilling mud is ejected radially from the bit 
nozzle, it is forced against the dams as the bit rotates to enhance 
flushing of the drill bit matrix. This flushing keeps the cutters cleaner 
and cooler, thus extending the useful life of the bit. 
The unique bit structure of the present invention provides several 
advantages over prior drill bits. Foremost, the nozzle provides high 
velocity radial fluid flow for greater cleaning and thus cooling potential 
while the spiraling dams structure assures that the high velocity fluid is 
distributed equally over the entire surface area of the bit face matrix. 
Since the cleaning fluid covers the entire bit surface, only an 
insignificant amount of erosion will occur around the nozzle area. Also, 
the radial fluid flow is advantageous since this is the direction that the 
debris must flow to be removed. As noted above, prior art fluid flow is 
perpendicular to the horizontal bit axis, thus requiring an expenditure of 
energy to change the direction of the flow path. Finally, the nozzle 
provides enough clearance between the rock foundation and the bit face 
matrix so that larger debris chips can be generated, therefore reducing 
drilling time. 
Although the invention has been described in detail, it is to be clearly 
understood that the same is by way of illustration and example only and is 
not to be taken by way of limitation, the spirit and scope of the 
invention being limited only to the terms of the appended claims.