U.S. patent number 3,583,501 [Application Number 04/804,838] was granted by the patent office on 1971-06-08 for rock bit with powered gauge cutter.
This patent grant is currently assigned to Mission Manufacturing Company. Invention is credited to Carl V. Aalund.
United States Patent |
3,583,501 |
Aalund |
June 8, 1971 |
ROCK BIT WITH POWERED GAUGE CUTTER
Abstract
A solid, button-insert-type percussion bit is disclosed having a
generally cylindrical body with a forwardly facing surface provided
with hardened cutter inserts and a rearward, anvil-forming portion.
A diagonal chamber in the bit body reciprocably mounts a plunger
having a cutter element on its forward face in such position as to
be driven against the periphery of the bottom of the hole being
drilled. A passage connects the chamber in back of this plunger
with the forward working chamber of the percussion drill motor so
that the small plunger and its cutter are driven outwardly to
maintain the gauge of the hole each time the forwardly facing
cutter elements are driven forwardly by axial blows applied by the
hammer piston.
Inventors: |
Aalund; Carl V. (Houston,
TX) |
Assignee: |
Mission Manufacturing Company
(Houston, TX)
|
Family
ID: |
25189983 |
Appl.
No.: |
04/804,838 |
Filed: |
March 6, 1969 |
Current U.S.
Class: |
175/96; 173/78;
173/80 |
Current CPC
Class: |
E21B
10/56 (20130101); E21B 10/00 (20130101); E21B
4/06 (20130101); E21B 6/00 (20130101); E21B
10/36 (20130101) |
Current International
Class: |
E21B
10/56 (20060101); E21B 10/36 (20060101); E21B
10/46 (20060101); E21B 6/00 (20060101); E21B
4/06 (20060101); E21B 4/00 (20060101); E21B
10/00 (20060101); E21b 005/00 () |
Field of
Search: |
;175/92,95,96
;173/78,80 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Claims
I claim:
1. A percussion-type rock bit comprising a solid body with forward
working surface and sidewall structure and a rearward,
anvil-forming part, hardened cutter inserts in said surface, a
chamber extending diagonally into said body from an opening therein
adjacent the intersection of said wall structures, a plunger
reciprocable in said chamber along a line inclined to the axis of
said body, a hardened cutter element on the forward face of said
plunger, and a fluid passage extending from said chamber through
said anvil-forming part for transmitting to said plunger operating
fluid pressures to which said anvil-forming part is subjected.
2. In combination in a percussion drill, a differential fluid
pressure motor including a working cylinder, an anvil received in
the forward part thereof, a hammer piston reciprocable in said
cylinder for beating upon said anvil, a rock bit on the forward
part of said anvil having a body with forward and sidewall
structures, hardened cutter inserts in said forward wall structure
for applying blows from said piston axially to the bottom of a hole
being drilled, an exhaust and cleanout fluid duct extending through
said anvil and said body, a chamber extending diagonally into said
body from an opening adjacent the intersection of said body forward
and sidewall structures, a plunger reciprocable in said chamber, a
hardened cutter element on the forward face of said plunger, and a
fluid passage connecting said chamber rearwardly of said plunger to
said working cylinder forwardly of said hammer piston for causing
said element to apply a forward and outward blow to the periphery
of the hole being drilled for maintaining the gauge of the
hole.
3. The combination described in claim 2 in which said motor
includes a control rod extending axially through said working
cylinder and said piston and into said anvil and connecting with
said exhaust duct therein, tubular means in said exhaust duct and
normally connecting with said control rod for transmitting motor
exhaust through said anvil and bit, said fluid passage under normal
working conditions being disconnected from said exhaust duct, said
anvil being forwardly movable in said working cylinder when said
motor is suspended off bottom to cause disconnection of said
tubular means and said control rod and direct connection of said
exhaust duct and said working cylinder forward part.
4. A drilling tool as described in claim 2 further including means
retarding the forward motion of said plunger to permit buildup of
fluid pressure thereon sufficient to produce a sharp cutting blow
of said cutting element.
Description
This invention relates to percussion rock bits, particularly of the
solid type, having hardened cutter inserts mounted in and
projecting from the forward face and periphery thereof.
Normally, rotary-cone-type bits are used for deep hole drilling,
whether of the conventional rotary type or in cooperation with a
downhole type of percussion motor. This is because no fully
satisfactory way has been provided for maintaining the size or
gauge of the hole when solid-type bits are used for this purpose.
However, rotary cone bits do not possess the strength
characteristics of solid-type bits and, therefore, cannot be
subjected to the full potential energy output which may be
developed by modern downhole percussion tools. More particularly,
with the use of solid-type bits, rapid wear on the outside diameter
of the body results in unacceptable loss of hole gauge long before
the face cutters of the bit are worn out. In some cases, complete
failure of the peripheral cutting elements due to the pinching
action of the bit makes it necessary to pull the bit early.
Furthermore, reinsertion of the new or repaired bit is difficult
because of the reduced size of the hole, as explained.
Accordingly, an object of the present invention is to provide a
solid-type rock bit which is sufficiently rugged for use with
high-pressure, percussion-type downhole tools and which will
effectively maintain the desired hole gauge.
Another object is to provide such a bit having means whereby an
axial percussive blow upon the bit body is accompanied by an
outward cutting stroke of one or more cutting elements which will
effectively maintain the original diameter or gauge of the
hole.
Another object is to provide a novel, percussion-type bit which
incorporates individually powered means for drilling the hole
slightly larger than the diameter of the bit body so as to reduce
bit wear and facilitate reinsertion of the new bit into the
hole.
These objects and others are attained by means of the
herein-disclosed device which comprises a solid-type rock bit body
having a forward working face which is provided with hardened
cutter inserts and a rear portion which forms the anvil of a
percussion-type drill motor. One or more gauge cutters are
provided. Each comprises a small, cylindrical chamber extending
diagonally rearwardly and inwardly from an opening at or adjacent
the intersection of the bit forward and side surfaces, and a
plunger reciprocable in this chamber carries a hardened cutter
element in its forward face. The plunger is urged rearwardly by a
spring. A control passage connects the chamber in back of the
plunger with the forward working chamber of the percussion motor
whereby fluid pressure conditions in the mentioned forward working
chamber are transmitted to the plunger for impelling the same and
its cutter element diagonally against the corner of the hole being
drilled, so as to chip the corner and therefore maintain the
diameter of the hole slightly larger than the diameter of the bit
body itself. During each upward or return movement of the hammer
piston during normal operation, the pressure in the forward working
chamber rises sufficiently to drive the mentioned plunger and
cutter forwardly against the corner of the hole being drilled. A
small, rearward boss on the plunger normally enters the mentioned
control passage. This boss permits sufficient delay after
commencement of the return stroke of the hammer piston so that the
pressure in the control passage builds up sufficiently to cause
advance of the plunger and its cutter element at a high rate of
speed.
In the accompanying drawings which illustrate the invention,
FIG. 1 is a longitudinal transverse section illustrating in part a
form of percussion motor which may be combined with the
herein-disclosed novel rock bit.
FIG. 2 is a similar view showing the forward portion of the motor
of FIG. 1 together with the novel rock bit in normal operating
position.
FIG. 3 is a sectional view similar to FIG. 2, rotated somewhat from
the position of FIG. 2 and showing the rock bit in the abnormally
advanced position incident to suspension of the motor off
bottom.
FIG. 4 is a graphical representation of various parameters during
operation of the motor.
The novel percussion drill motor illustrated in FIGS. 1 and 2 is
more fully disclosed and claimed in U.S. Pats. Nos. 3,229,776 and
3,105,559 assigned to the assignee of the present application. This
motor comprises a ruggedly built, cylindrical casing 6 for
connection at its upper end 7 with a source of fluid pressure, for
instance, a conventional drill string, and having a coarse thread 8
at its lower end for reception of a split adapter nut 9 which, in
turn, slidably receives the anvil 10 by means of splines 11. At the
lower or forward end of anvil 10 there is provided, in this case
integrally, a bit body 12 having a downward or forward face 13
provided with propitiously arranged, hardened cutting inserts 14. A
chamber 15 is provided at the intersection of forward surface 13
and generally cylindrical side surface 16 of the body. The upper
end of the anvil is provided with a guide enlargement 17 slidably
received within casing 6. An axial duct 18, 19, 20 extends through
the anvil in part, as will be explained, for conducting motor
exhaust which cools and lubricates the bit cutters and carries
cuttings to the surface of the hole, in the usual manner. The upper
end 21 of nut 9 underlies anvil enlargement 17 to prevent the anvil
from dropping out the bottom of the casing.
Reciprocably received within casing 6 is the hammer piston 24
having thickened central portions 25 and 26 which slide along the
casing inner surface, and an internal annular shuttle groove 27. A
control rod, generally designated 28, extends axially through the
motor from its upper end, where it connects to the source of
operating fluid pressure, for instance, the interior of the
supporting drill stem, through an axial passage 29 in the hammer
piston and into the upper portion 18 of the anvil passage. The
control rod is formed of a central body portion 30 and an outer
shell 31 forming between them upper longitudinal passages 32 and
lower longitudinal passages 33 connecting, respectively, ports 34
and 35 leading to upper working chamber 36 and lower ports 37 and
38 leading to lower working chamber 39. A high-pressure or working
fluid passage 40 extends axially through the control rod and has a
choke 41 at its lower end providing a constant bypass of working
fluid. Central supply ports 42 connect working fluid passage 40
with shuttle groove 27. Exhaust passages, represented by dotted
lines 43, are also provided between rod core 30 and shell 31
connecting, respectively, an upper exhaust port 44 opening to upper
working chamber 36 and a lower exhaust port 45 for connecting lower
working chamber 39 with exhaust duct 66 in the anvil, to be
described. A blowing port 46 also opens into exhaust passage 43
and, normally, is covered by the hammer piston.
As explained in the above-mentioned patents, during normal
operation of the motor with the bit resting on bottom and the lower
edge 9a of nut 9 resting on bit shoulder 12a, working fluid
supplied through control rod passage 40 is alternately shuttled by
means of groove 27 in the hammer piston 24 to lower working chamber
39 to lift the hammer piston and to upper working chamber 36 to
drive the hammer piston downwardly in its power stroke. In the
lowermost position of the hammer piston, upon striking the upper
surface 47 of the anvil, upper exhaust port 44 will be exposed
above the hammer piston so as to exhaust pressure from upper
chamber 36. At the uppermost or turnaround position of the hammer
piston, the lower edge 48 thereof exposes lower exhaust port 45 to
exhaust lower working chamber 39. When the tool is suspended off
bottom (FIG. 3), anvil 10 will drop abnormally until enlargement 17
rests upon upper end 21 of adapter nut 9. At this time, shuttle
groove 27 will somewhat overlap blowing port 45 so that the
high-pressure working fluid will flow directly through exhaust
passages 43 into anvil exhaust duct 18, etc. As will be explained
hereafter, lower working chamber 39 will be vented at the same
time.
With reference to FIG. 2, a small, cylindrical chamber 50 extends
diagonally inwardly and rearwardly from the intersection of forward
face 13 and side face 16 of the bit and is provided with a liner 51
having a countersunk upper portion, as at 52, and slidably
receiving a small, elongated plunger 53 having an upper collar 54.
A coiled compression spring 55 normally urges collar 54 against a
shoulder 56 at the upper end of chamber 50 and has a hardened
cutter insert 57 at its lower end. Collar 54 has a central boss 58
which normally enters the countersunk lower portion 59 of a
diagonal control passage 60 extending to and opening into
intermediate portion 19 of the exhaust duct through the anvil.
The upper portion 18 of the anvil passage is of somewhat greater
diameter than the lower extremity 28a of the control rod so as to
provide an annular passage 62 between the rod and anvil. A
frustoconical shell 63, in this case welded to the lower end of
control rod shell 31, extends below the control rod and, normally,
slidably receives the upper end portion 64a of a tubular structure
64 which is lodged in intermediate portion 19 of the anvil passage.
Conical lugs 64b on structure 64 rest against incline 19a in the
anvil passage while permitting free passage of fluid therepast. A
sealing O-ring 64c is provided at the lower end of structure 64.
The intermediate portion 64d of the tubular structure is slightly
spaced from the intermediate portion 19 of the anvil passage to
provide an annular passage 65 with which previously mentioned
diagonal control passage 60 communicates exteriorly and, normally,
independently of the exhaust duct 66 through structure 64.
FIG. 4 represents diagrammatically the pressure conditions above or
behind hammer piston 24 (curve A), pressure conditions beneath
(forwardly) of the hammer piston (curve B), and the position of the
hammer piston (curve C). In each case, the abscissae represent
time, the total time of a cycle of the hammer piston in this
instance being approximately 0.060 seconds. The ordinates in the
case of curves A and B represent pounds-per-square-inch absolute.
The ordinates with respect to curve C represent inches. The line D
represents the critical pressure beneath the hammer and in passage
60 at which boss 58 on plunger 53 advances from passage countersink
59 to expose the entire area of collar 54 to the pressure in
control passage 60. Thus, lug 58 has the effect of limiting the
advanced positioning of cutter 57 during which the striking blow
occurs, to the time between the points 70 and 71 on the curve B
during which plunger 53 drives quickly downwardly and outwardly to
stroke a chipping blow against the corner portion 72 of the hole
bottom. Maximum pressure in passage 60 and in forward working
chamber 39 is reached at the point 73, while at the point 74,
maximum pressure is reached in the upper working chamber just prior
to TDC of the hammer piston. Critical pressure beneath the hammer
(Curve B) is again reached at point 71 which permits spring 55 to
return the plunger to its rest position, with boss 58 in passage
countersink 59. The return motion of the plunger between points 71
and 75 occupies approximately 80 percent of the cycle time.
Following the guage-cutting stroke and dwell of the plunger, the
hammer enters its power stroke and ultimately strikes the anvil.
Just before striking of the anvil, pressure in forward working
chamber 39 reaches the low point 76 (curve B). Soon this pressure
begins to build up and, when line D is reached, a chipping blow of
plunger 53 is again initiated.
Thus, the frequency of the gauge-cutting device is the same as that
of the main hammer piston. One or more of the gauge-cutting devices
may be provided, as needed, to insure drilling of the hole at a
diameter slightly greater than the diameter of the bit proper. The
dimensions of the percussion motor will be adjusted to accommodate
the slight increase of volume which must be filled by working fluid
during lifting of the hammer piston. The alternate axial and
diagonal blows will continue as long as the tool is on bottom and
the lower end of adapter 8 rests on shoulder 75 of the bit.
FIG. 3 shows the tool rotated so that the gauge cutter is out of
the plane of the view and the tool is hanging. The upper portion
64a of the tubular structure will withdraw from conical shell 63
(FIG. 3) permitting venting of lower working chamber 39 through
passage 18 and the clearance 76 between shell 63 and the tubular
structure. Moreover, at this time, insufficient pressure will be
developed in passage 60 to cause actuation of diagonal plunger 53.
Thus, the hammer piston will remain motionless in its lowermost
position, while plunger 53 will remain in its uppermost position
and the full force of working fluid will "blow" through exhaust
duct 66, 20.
The particular type of percussion motor shows is exemplary, but any
other type may be used with the novel rock bit structure, provided
a control pressure can be tapped which fluctuates so as to produce
the periodical gauge-chipping action of the individual cutting
plungers 53. High-pressure passaging 18, 19 leading to the gauge
cutter may be otherwise formed and may communicate directly with
another part of the percussion motor, for instance, top chamber 36.
Moreover, in a broad sense, other types of percussive action may be
utilized and distributed to provide more-or-less concurrent or
sequential axial and diagonal or lateral cutting blows.
The invention may be modified in various respects as will occur to
those skilled in the art and the exclusive use of all modifications
as come within the scope of the appended claims as
contemplated.
* * * * *