U.S. patent application number 14/888506 was filed with the patent office on 2016-03-31 for percussive rock drill bit.
This patent application is currently assigned to SANDVIK INTELLECTUAL PROPERTY AB. The applicant listed for this patent is SANDVIK INTELLECTUAL PROPERTY AB. Invention is credited to Per MATTSON, Magnus PERSSON.
Application Number | 20160090791 14/888506 |
Document ID | / |
Family ID | 48288871 |
Filed Date | 2016-03-31 |
United States Patent
Application |
20160090791 |
Kind Code |
A1 |
PERSSON; Magnus ; et
al. |
March 31, 2016 |
PERCUSSIVE ROCK DRILL BIT
Abstract
A percussive rock drill bit includes a head provided at one end
of a rearwardly projecting skirt. The head has an outer collar that
defines, in part, a rearwardly projecting recess formed in the
forwardmost region of the head. Peripheral gauge buttons are
provided at the collar to surround side and front facing buttons
formed at the head recess. The drill bit is effective to provide
stabilised cutting to minimise lateral deflection.
Inventors: |
PERSSON; Magnus; (Sandviken,
SE) ; MATTSON; Per; (Sandviken, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SANDVIK INTELLECTUAL PROPERTY AB |
Sandviken |
|
SE |
|
|
Assignee: |
SANDVIK INTELLECTUAL PROPERTY
AB
Sandviken
SE
|
Family ID: |
48288871 |
Appl. No.: |
14/888506 |
Filed: |
April 11, 2014 |
PCT Filed: |
April 11, 2014 |
PCT NO: |
PCT/EP2014/057389 |
371 Date: |
November 2, 2015 |
Current U.S.
Class: |
175/415 |
Current CPC
Class: |
E21B 10/36 20130101;
E21B 10/40 20130101 |
International
Class: |
E21B 10/40 20060101
E21B010/40 |
Foreign Application Data
Date |
Code |
Application Number |
May 3, 2013 |
EP |
13166428.6 |
Claims
1. A percussive rock drill bit comprising: a head coupled to a
rearwardly projecting skirt, a longitudinal axis extending through
the head and the skirt, the head having a front face and an outer
collar being raised and projecting axially forward of the front
face, the collar having an inner sloping surface inclined relative
to the axis and being radially inward facing such that the front
face and the sloping surface define a rearwardly projecting cavity
in a forward region of the bit; a plurality of gauge buttons
distributed over the collar and mounted at the head to tilt
radially outward from the axis; a plurality of front buttons
distributed over the front face; and a plurality of side buttons
distributed over the inner sloping surface of the collar wherein at
least a portion of each gauge button is positioned axially
forwardmost of each side button.
2. The drill bit as claimed in claim 1, wherein each side button is
mounted at the head to tilt radially inward towards the axis.
3. The drill bit as claimed in claim 1, wherein a diameter of the
gauge buttons is greater than a diameter of the side buttons.
4. The drill bit as claimed in claim 1, a diameter of the gauge
buttons is greater than a diameter of the front buttons.
5. The drill bit as claimed in claim 1, wherein the gauge buttons
are tilted radially outward from the axis at an angle in the range
of 30 to 45.degree..
6. The drill bit as claimed in claim 1, wherein the side buttons
are tilted radially towards from the axis at an angle in the range
of 30 to 45.degree..
7. The drill bit as claimed in claim 5, wherein the gauge buttons
and the side buttons are tilted at an angle of substantially
40.degree..
8. The drill bit as claimed in claim 1, wherein the collar includes
a peripheral surface extending around the inner sloping surface and
orientated to be declined relative to the axis to be radially
outward facing, the gauge buttons projecting from the peripheral
surface.
9. The drill bit as claimed in claim 1, wherein the gauge, front
and side buttons are selected from the group of a domed shape
configuration, a rounded shape configuration, a conical shape
configuration, a ballistic shape configuration a semi-spherical
shape configuration, a flat end configuration and a combination
thereof.
10. The drill bit as claimed in claim 1, comprising eight gauge
buttons.
11. The drill bit as claimed in claim 1, comprising six side
buttons.
12. The drill bit as claimed in claim 1, comprising four front
buttons.
13. The drill bit as claimed in claim 1, wherein the collar
includes at least one groove extending axially between an end
peripheral surface and the front face.
14. The drill bit as claimed in claim 1, wherein the collar
includes at least one channel extending from an end peripheral
surface axially towards the front face.
Description
FIELD OF INVENTION
[0001] The present invention relates to a percussive rock drill bit
and in particular, although not exclusively, to a drill bit formed
with a cutting head mounting a plurality of peripheral gauge
buttons and front buttons configured to cut material via a guiding
cone action to optimize the rock breaking and cutting
operation.
BACKGROUND ART
[0002] Percussion drill bits are widely used both for drilling
relatively shallow bores in hard rock and for creating deep
boreholes. For the latter application, drill strings are typically
used in which a plurality of rods are added to the string via
coupling sleeves as the depth of the hole increases. A terrestrial
machine is operative to transfer a combined impact and rotary drive
motion to an upper end of the drill string whilst a drill bit
positioned at the lower end is operative to crush the rock and form
the boreholes. Fluid is typically flushed through the drill string
and exits at the base of the borehole via apertures in the drill
head to flush the drill cuttings from the boring region to be
conveyed backward and up through the bore around the outside of the
drill string. It is a typical requirement that the borehole should
be as straight as possible particularly where the drilling is
directed to a predetermined target deep below the earth surface.
This commonly involves the drill bit passing through many different
types of rock formation. Example percussive drill bits are
disclosed in U.S. Pat. No. 3,388,756; U.S. Pat. No. 3,357,507, US
2008/0087473; and WO 2009/067073.
[0003] The drill bit typically comprises a drill head that mounts a
plurality of hard cutting inserts, typically referred to as
buttons. Such buttons comprise a carbide based material to enhance
the lifetime of the drill bit. In particular, WO 2006/033606
discloses a rock drill bit having a head with a plurality of
peripheral gauge buttons distributed circumferentially at an outer
perimeter of the drill head. The gauge buttons are configured to
engage material to be crushed and to determine the diameter of the
borehole. The head also mounts a plurality of front buttons
provided at a recessed front face of the drill head for engaging
material to be crushed at the axial region immediately in front of
the drill head.
[0004] However, conventional drill bits are susceptible to
deflection and non-uniform bore creation due for example to
anomalies in the rock structure such as cracks, fissures and sudden
changes in the rock structure and type. There is therefore a need
for an improved percussive drill bit that addresses these
problems.
SUMMARY OF THE INVENTION
[0005] It is an objective of the present invention to provide a
percussive rock drill bit configured to aggressively break through
subterranean materials including in particular rock and minerals
via a combined impact and rotary motion. In particular, it is a
specific objective to provide a drill bit that impacts through
fault and cracks in the rock via a cutting action in which the
drill bit is self-stabilising via a shape profile created in the
rock during rotation.
[0006] The objectives are achieved by providing a drill bit head
having a plurality of cutting inserts aligned and positioned at
different regions of a cutting head to perform different functions
and in particular to stabilise the drill head as it is rotated and
advanced through the subterranean material. In particular, the
inventors have identified advantages with providing a head having
outer peripheral gauge buttons that are tilted outwardly from a
central longitudinal axis of the drill bit and are positioned
axially forwardmost of any other component of the drill head.
Additionally, the drill head, at a forward facing region, comprises
a rearwardly projecting cavity or recess within which are mounted
front facing buttons, (positioned at the lowest region of the
cavity) and side buttons (positioned at the circumferential cavity
sides and radially inside the gauge buttons). The front and side
buttons of the cavity are effective to create a `cone` shaped
projection in the rock as the drill bit is rotated and advanced.
This cone formation is provided by the relative size and
orientation of the front and side buttons. In particular, the side
buttons are tilted radially inward towards the axis such that a tip
(or a leading cutting edge) of the buttons is positioned closer to
the axis than a base of the buttons embedded in the drill head.
Additionally, the peripheral gauge buttons are advantageously
tilted radially outward such that their tip (or leading cutting
edge) is positioned radially furthest from the axis than a base
region of the buttons embedded in the drill head.
[0007] It is a further advantage of the subject invention that the
outer peripheral gauge buttons are effective to create an annular
groove in the rock during rotation with this annular groove
surrounding the guiding cone. The inventors have identified that
this annular groove is effective to further stabilise the drill
head during rotation and advancement. This is achieved, in part,
via the relative axial positioning of the gauge buttons being
axially forwardmost of the side and front buttons.
[0008] According to a first aspect of the present invention there
is provided a percussive rock drill bit comprising: a head coupled
to a rearwardly projecting skirt, a longitudinal axis extending
through the head and the skirt; the head having a front face and an
outer collar being raised and projecting axially forward of the
front face, the collar having an inner sloping surface being
inclined relative to the axis and being radially inward facing such
that the front face and the sloping surface define a rearwardly
projecting cavity in a forward region of the bit; a plurality of
gauge buttons distributed over the collar and mounted at the head
to tilt radially outward from the axis; a plurality of front
buttons distributed over the front face; characterised by: a
plurality of side buttons distributed over the inner sloping
surface of the collar wherein at least a portion of each gauge
button is positioned axially forwardmost of each side button.
[0009] Preferably, each side button is mounted at the head to tilt
radially inward towards the axis.
[0010] Reference within the specification to `buttons` encompasses
inserts adapted specifically to be harder than the main body of the
drill (being typically steel) including the drill head. The cutting
inserts may typically comprise a carbide based material such as
cemented carbide or tungsten carbide for example.
[0011] Optionally, a diameter or width of the gauge buttons is
greater than a diameter or width of the side buttons. Optionally, a
diameter or width of the gauge buttons is greater than a diameter
or width of the front buttons.
[0012] Optionally, the gauge buttons are tilted radially outward
from the axis at an angle in the range 30 to 50.degree., 30 to
45.degree., 35 to 45.degree.. Optionally, the side buttons are
tilted radially towards from the axis at an angle in the range 30
to 50.degree., 30 to 45.degree., 35 to 45.degree.. Preferably, the
gauge buttons are tilted radially outward from the axis at an angle
of substantially 40.degree. and the side buttons are tilted
radially towards the axis at an angle of substantially
40.degree..
[0013] Preferably, the collar comprises a peripheral surface
extending around the inner sloping surface and orientated to be
declined relative to the axis to be radially outward facing, the
gauge buttons projecting from the gauge surface.
[0014] Preferably, the drill bit further comprises axially
projecting channels extending from a peripheral region of the
cutting head and along the length of the skirt. Optionally, the
drill head further comprises radially extending grooves formed in
the peripheral collar. Preferably, the drill bit further comprises
an annular flange provided at an axially rearward end, the flange
comprising a plurality of rearward facing teeth with a cutting
region to provide a cutting action when the drill bit is rotated
for extraction from the borehole.
[0015] Preferably, the drill bit further comprises at least one
fluid supply conduit formed internally within the drill bit and
extending axially rearward from the cutting head and in particular
the front face. Preferably, the drill bit further comprises an
axially inner bore extending lengthwise within the main body of
drill bit to mount the drill bits on a shaft of the terrestrial
machine to impart the impact and rotary motion.
[0016] Optionally, the gauge, front and/or side buttons comprise
any one or a combination of the following: a domed shape
configuration; a rounded shape configuration; a conical shape
configuration; a ballistic shape configuration; a semi-spherical
shape configuration; a flat end configuration. Preferably, the
buttons (optionally turned hardened inserts) are embedded into the
cutting head via conventional manufacturing methods known to those
skilled in the art.
[0017] Optionally, the drill bit comprises eight gauge buttons.
Optionally, the drill bit comprises six side buttons. Optionally,
the drill bit comprises four front buttons.
[0018] Preferably, the collar comprises at least one groove
extending axially between an end peripheral surface and the front
face. Optionally, collar comprises at least one channel extending
from an end peripheral surface axially towards the front face.
BRIEF DESCRIPTION OF DRAWINGS
[0019] A specific implementation of the present invention will now
be described, by way of example only, and with reference to the
accompanying drawings in which:
[0020] FIG. 1 is an upper perspective view of the percussive rock
drill bit having a skirt and a drill head mounting a plurality of
cutting inserts (buttons) according to a specific implementation of
the present invention;
[0021] FIG. 2 is a lower perspective view of the drill bit of FIG.
1;
[0022] FIG. 3 is a plan view of the head region of the drill bit of
FIG. 2;
[0023] FIG. 4 is an external side elevation view of the drill bit
of FIG. 2;
[0024] FIG. 5 is a cross sectional side view through A-A of FIG.
4;
[0025] FIG. 6 is a magnified view of the inserts mounted at the bit
head of FIG. 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION
[0026] Referring to FIGS. 1 to 4 a drill bit 100 comprises a drill
head 101 formed at one end of a generally elongate shaft 108. An
opposite end of shaft 108 is flared radially outward to provide an
annular flange 109. Shaft 108 and flange 109 collectively define a
skirt 102 that represents a trailing region of drill bit 100 as it
is advanced through the rock or subterranean material via the
leading drill head 101. A plurality of axially extending channels
111 are recessed into the outer surface of skirt 101 and extends
almost the entire axial length of drill bit 100. Channels 111
terminate at head region 101 to create depressions 114 that extend
radially inward towards a central longitudinal axis 119 (extending
through drill bit 100) from a radially outermost peripheral edge
120 of head 101. The circumferentially spaced apart channels 111
define intermediate axially extending ridges 110 that are also
provided over the substantially entire axial length of drill bit
100.
[0027] A plurality of cutting teeth 112 are provided at an axially
rearward region 121 of skirt 102 and in particular annular flange
109. Teeth 112 comprise an axially rearward facing cutting surface
200 configured to facilitate extraction of the drill bit 100
backwards through the borehole created by the advancing head 101.
Teeth 112 are formed at the end regions of each ridge 110.
[0028] Head 101 is flared radially outward relative to shaft 108
and comprises a maximum diameter being approximately equal to a
diameter of flange 109 to form a raised outer collar represented
generally by reference 107. Collar 107 forms a perimeter of a
cavity 103 that projects axially rearward from a forwardmost
annular rim 122 of collar 107. Cavity 103 is also defined, in part,
by a sloping side surface 105 that is tilted radially outward from
axis 119. The inclined side surface 105 is terminated at an upper
end by annular rim 122 and at a lower end by a front facing surface
106. Front surface 106 is aligned substantially perpendicular to
axis 119 and comprises a generally circular configuration.
[0029] Collar 107 is further defined, in part, by a peripheral
surface 104 that extends circumferentially and radially outward
beyond rim 122. Peripheral surface 104 is terminated by radially
outermost edge 120. Surface 104 is tilted radially outward from
axis 119 so as to be generally outward facing whilst cavity side
surface 105 is orientated to be generally inward facing towards
axis 119. A head trailing surface 123 extends axially rearward of
peripheral surface 104 and is also orientated transverse to axis
119 so as to decrease the diameter of collar 107 towards a diameter
of shaft 108. According to the shape profile and configuration of
head 101 and in particular the peripheral raised collar 107, cavity
region 103 comprises a generally bowl or dish-shaped configuration
in which the sides of the bowl are defined by sloping surface 105
and the base of the bowl is defined by front surface 106. A pair of
diametrically opposed grooves 113 are formed within collar 107 from
axially forwardmost rim 122 to an axial depth aligned with front
surface 106. Each groove 113 comprises a generally V-shaped
configuration in which a width of the groove at its lower region
(corresponding to front face 106) is smaller than a corresponding
width at an upper region (corresponding to rim 122). Some channels
111 terminate at head 101 to form depressions 114 recessed axially
and extending radially through the forwardmost region of collar 107
from rim 122. Depressions 114 and grooves 113 allow debris material
to pass radially outward from cavity 103 to a region outside of
drill bit 100. Additionally some channels 111 terminate at head 101
to form indents 124 in the radially outermost region 120 of collar
107, where such indents 124 do not extend radially through the
collar wall to emerge at cavity 103.
[0030] Drill head 101 comprises three types of hardened cutting
inserts (referred to herein as buttons). A first set of buttons 115
are positioned at peripheral surface 104 and are configured as
gauge buttons to determine and maintain a predetermined diameter of
the borehole formation. Gauge buttons 115 are tilted radially
outward so as to be generally inclined and outward facing from axis
119 consistent with peripheral surface 104. Gauge buttons 115 are
embedded within and distributed circumferentially around the
perimeter region of collar 107 to project axially forward of rim
122 and to represent collectively an axially forwardmost cutting
edge of drill bit 100. A second set of buttons 117 are embedded in
front facing surface 106 at the cavity base region 103. Buttons 117
are aligned generally with axis 119. A third set of buttons 116 are
embedded in the collar side wall at the inward facing sloping
surface 105. Buttons 116 are positioned at a region radially
intermediate the outer peripheral gauge buttons 115 and radially
inner front facing buttons 117. Side buttons 116 are mounted at the
collar wall region to tilt radially inward towards axis 119 having
an opposite angle of inclination to gauge buttons 115. Side buttons
116 are provided at different axial heights at sloping surface 105
such that at least one button is provided at an axially lower
position (towards front surface 106); at least one button 116 is
positioned axially higher (towards peripheral rim 122) and at least
one button 116 is positioned axially between these two upper and
lower buttons 116. Accordingly, the relative position of buttons
116 over surface 105 ensures a continuous cutting edge is formed
over the entire axial length of surface 105 between rim 122 and
front surface 106. Additionally and referring to FIG. 3, each gauge
button 115 comprises a region 300 that extends radially outward
beyond the outermost edge 120 of collar 107.
[0031] Referring to FIGS. 5 and 6 each of the three types of
cutting button 115, 116, 117 comprises a generally dome-shaped
cutting surface provided at one end of a generally elongate main
body. The main body of each button 115, 116, 117 is embedded within
drill head 101 such that only the domed surface protrudes to
represent semi spherical cutting surfaces. Outer gauge buttons 115
comprise a domed end portion having a diameter greater than that of
side and front buttons 116, 117. Side buttons 116, 117 comprise
approximately equal diameter domed head portions. The elongate main
body of gauge buttons 115 are tilted radially outward as
illustrated by reference 502 relative to longitudinal axis 119. The
inclined angle a is typically between 30 to 45.degree. and is
substantially 40.degree.. Accordingly, the domed head surface 115
projects generally radially outward from axis 119. Additionally,
each elongate main body of side buttons 116 is mounted at head 101
so as to tilt towards axis 119 to be generally inward facing. An
angle of inclination .beta. of side buttons 116 is represented by
reference 503 and is typically between 30 to 45.degree. and is
substantially 40.degree. relative to axis 119. As illustrated in
FIG. 5, the front buttons 117 comprise a main body that is aligned
substantially parallel with axis 119 as indicated by reference
504.
[0032] Drill bit 100 comprises an elongate central bore 200
extending from the axially rearward region 121 to head 101. An
opening 501 of bore 200 is flared radially outward and a
corresponding innermost region 500 of bore 200 is also flared
radially outward to engage and mate with a driving tool coupled to
the terrestrial machine to impart the hammer-like impacting force
and a rotary motion to bit 100. A plurality of fluid conduits 118
extend from bore 200 to emerge from front facing surface 106 to
provide a fluid flow pathway. Accordingly, a fluid may be provided
to drill bit 100 to flow through bore 200 and conduits 118 to the
cavity region 103. Cutting debris is then flushed from head 101 via
grooves 113 and depressions 114 to be carried rearwardly through
channels 111.
[0033] Referring to FIG. 6, each gauge button 115 comprises a
region 500 of the domed cutting surface that is positioned axially
forward from a corresponding region 501 of the domed cutting
surface of each side button 116. Accordingly, the axially
forwardmost region 500 of gauge button 115 is positioned axially
proud of the axially forwardmost region 501 of side button 116 by a
distance d. According to the specific implementation, distance d is
substantially 0.3 to 1.5 mm and is in particular 0.5 or 0.7 mm.
[0034] In use, drill bit 100 is configured to rotate about axis
119. As the gauge buttons 115 are positioned axially forwardmost
and radially outermost, these cutting components 115 provide the
principal cutting action through the rock. In particular, the
radially outward tilting orientation of gauge buttons 115 provides
that cutting head 101 creates an annular groove in the rock at the
leading end region of drill bit 100. This as-formed groove is
effective to stabilise bit 100 and inhibit undesirable lateral
deflection from axis 119 during advancement. Additionally, the
relative orientation and configuration of side buttons 116 and
front facing buttons 117 (mounted within recess 103) are affective
to create a `guide cone` in the rock as drill bit 100 advances.
This guide cone projects rearwardly into cavity 103 from rim 122
and is surrounded by the as-formed annular groove created by gauge
buttons 115. The formation of the guide cone is optimised by the
tilting angular alignment of side buttons 116 to be inward facing
towards axis 119. The relative axial positioning of gauge regions
115 relative to side button regions 116 ensures the leading groove
is continually formed circumferentially around the guide cone to
provide a combined means of anchorage of the drill bit 100 within
the borehole. The present configuration of the three types of
cutting insert 115, 116, 117 provide that the drill bit 100 is
effective to aggressively break through fault and cracks in the
rock.
[0035] The present invention is not limited to the above described
embodiments. Different alternatives, modifications and equivalents
might be used. The above mentioned embodiments should therefore,
not be considered limiting to the scope of the invention, which is
defined by the patent claims.
* * * * *