Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/36—Percussion drill bits
  • E21B10/38—Percussion drill bits characterised by conduits or nozzles for drilling fluids
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/60—Drill bits characterised by conduits or nozzles for drilling fluids

Definitions

• the present invention relates to a rock drill bit and in particular, although not exclusively, to a percussive rock drill bit having a head and an axially rearward skirt along which lengthwise ribs project radially outward to define sludge channels configured for the axially rearward transport of fluid and cut rock.
• Percussion drill bits are widely used both for drilling relatively shallow bores in hard rock and for creating deep boreholes.
• a drill string is typically used in which a plurality of rods are coupled end-to-end via threaded joints as the depth of the bore 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.
• WO 2006/033606 discloses a typical drill bit comprising a drill head that mounts a plurality of hard cutting inserts, commonly referred to as buttons. Such buttons comprise a carbide based material to enhance the lifetime of the drill bit.
• 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 rock cuttings from the boring region to be conveyed rearward around the outside of the drill string.
• the effectiveness of the drill bit to bore into rock is dependent upon the rearward transport of the rock fragments from the cutting region.
• the cut rock combined with the flushing fluid typically forms a sludge and it is important the sludge is transported rearwardly during cutting to avoid recrushing of the rock and a corresponding shortening of the operational lifetime of the drill bit.
• non-transported sludge acts to block the bore and inhibit axially rearward extraction of the drill bit in addition to increasing the risk of possible collapse of the borehole during bit extraction. Accordingly, there is a need for a drill bit to address these problems.
• a drill bit having a skirt extending axially rearward from a cutting head that comprises sludge grooves specifically adapted for the axially rearward transport of rock debris and flushing fluid both during axially forward drilling and axially rearward extraction of the drill bit.
• the sludge grooves at the skirt are defined by axially extending ribs that in the lengthwise direction of the ribs between the bit head and an axially rearwarmost part of the skirt are bent or curved relative to the longitudinal axis of the drill bit so as to be aligned oblique to the longitudinal axis.
• the ribs that define the sludge grooves have a length component that may be regarded as deflected so as to deviate in a circumferential direction around the axis.
• the lengthwise path of the ribs and the channels may be helical around the axis.
• a drill bit comprising: a head having cutting elements to abrade rock by rotation of the drill bit about its longitudinal axis; a skirt extending axially rearward from the head; a plurality of ribs projecting radially outward and extending axially along the skirt to define axially extending channels, the rib and channels each having a length extending axially in a direction between the head and an axially rearward end of the skirt; characterised in that: in the lengthwise direction at least a part of the ribs and channels are bent or curved such that the lengthwise part of the ribs or channels is oblique to the longitudinal axis.
• the ribs and channels comprise a corresponding width aligned in the circumferential direction and a depth extending in a radial direction.
• the width and depth may be uniform along the length of the ribs and channels or may be non-uniform.
• the lengthwise path of the ribs and channels along the skirt in a direction between the head and an axially rearwardmost part of the skirt is non parallel i.e., oblique to the longitudinal axis so as to extend at least to some extent in the circumferential direction around the axis.
• Reference within this specification to the ribs or channels being oblique to the longitudinal axis encompass the alignment of the ribs and channels being non-parallel to the bit longitudinal axis over at least a portion of their length.
• the orientation of the ribs or channels relative to the axis encompasses a general orientation with each rib being defined generally by a leading face, a leading edge, a land face, a trailing edge and a trailing face. Such faces and edges may be linear or curved but importantly at least some or all (over at least a part of their respective axial length) are aligned non-parallel to the longitudinal axis.
• the part of the ribs and channels that are oblique to the longitudinal axis are positioned at an axially rearward part of the skirt.
• an axially forward part of the ribs and channels are aligned generally parallel to the longitudinal axis.
• the linear axially forward part is effective to provide immediate rearward transport of the cut rock and flushing fluid whilst the oblique aligned axially rearward portion of the ribs and channels is effective to encourage the sludge to follow a helical or swirling flow pathway over the external surface of the drill string rearward from the drill bit.
• the axially rearward part extends up to 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% of the length of the skirt between an axially rearwardmost region of the head and the axially rearward end of the skirt.
• the axially rearward part extends over a majority of the length of the skirt.
• the axially rearward part extends over 30 to 80%, 40 to 80%, 50 to 80% or 50 to 70% of the length of the skirt between an axially rearwardmost region of the head and the axially rearward end of the skirt.
• the lengthwise part of the ribs and channels are at least part helical around the axis. This alignment is effective to provide a non-linear flow of the sludge axially rearward along the borehole and avoid the drill bit becoming stuck during extraction.
• each rib comprises a leading face and a trailing face separated by a radially outward facing land face, the leading and trailing faces at least partial defining the channels.
• the transition from the leading face to the trailing face within anyone channel may be continuously curved over a trough region of each channel.
• both the leading and trailing faces of the ribs are bent or curved in the same circumferential direction around the axis so as to be aligned oblique to the longitudinal axis.
• Such an arrangement is effective to appropriately channel the flushing fluid and cut rock into what may be considered a helical or swirling flow pathway over the external surface of the drill string.
• at least a part of a leading edge and a trailing edge of the ribs at the junction between the land face and the respective leading face and trailing face is bent or curved so as to be aligned oblique to the longitudinal axis.
• the part of the leading edge and the trailing edge that are oblique to the longitudinal axis are positioned at an axially rearward part of the skirt.
• the leading face is aligned generally normal to the rotational direction of the bit about the longitudinal axis. This configuration is beneficial to induce the flow of the sludge in the
• the trailing face is aligned transverse to the rotational direction of the bit and/or oblique to the leading face.
• an angle by which the ribs are bent or curved such that their length deviates in a circumferential direction is in the range 1 to 20°, 1 to 18°, 1 to 16°, 1 to 14°, 1 to 12°, 2 to 12°, 3 to 10°, 3 to 8° or 4 to 6° relative to the longitudinal axis.
• Such oblique alignment of the ribs is effective to prevent the drill bit getting stuck during extraction by appropriately directing the flushing fluid and cut rock axially rearward away from the drill bit.
• the drill bit further comprises an internal bore and passageways extending axially from a forward end of the bore to emerge as openings at a forward cutting face of the head, at least some of the channels extending axially along the head in communication with the openings.
• approximately half of the channels are provided in communication with the openings at the cutting face.
• the cutting elements comprise cutting buttons embedded into the head.
• the cutting buttons may be formed from a superhard carbide material according to
• the present drill bit may comprise any head configuration in addition to different cutting button distributions at the cutting head.
• the cutting buttons include gauge buttons, medial buttons and radially inner buttons provided at the cutting face.
• Figure 1 is a perspective view from above of a percussive drill bit according to a specific implementation of the present invention
• Figure 2 is a side perspective view of the drill bit of figure 1 ;
• Figure 3 is a perspective view from below of the drill bit of figure 2;
• Figure 4 is a rear end perspective view of the drill bit of figure 3.
• Figure 5 is a cross sectional perspective view of the drill bit of figure 3;
• a percussive drill bit 10 comprises a cutting head 11 from which extends axially rearward an elongate skirt 12.
• Head 11 comprises a forward facing cutting face 13 that, according to the specific implementation is domed in a forward cutting direction.
• a plurality of superhard cutting buttons are embedded into cutting face 13 and include radially outer gauge buttons l4a and inner buttons l4b as will be appreciated.
• Head 11 is provided with a raised annular shoulder 16 the axially forward region of which mounts gauge buttons l4a.
• skirt 12 is hollow and comprises an internal bore 26 centred on a longitudinal axis 19 of bit 10.
• a set of flushing fluid passageways 27 extend axially forward from a forward end 28 of bore 26 to emerge at cutting face 13 as openings 15.
• three fluid passageways are provided in communication with bore 26 to emerge at cutting face 13.
• a respective groove or channel l8a projects radially outward from each opening 15 in a direction from axis 19 to head shoulder 16.
• Channels l8a are recessed into cutting face 13 and also shoulder 16 to extend axially rearward from head 11 along the full axial length of skirt 12.
• Bit 10 comprises two types of flushing groove including a first channel l8a in fluid communication with each respective passageway 27 (and opening 15) and a second channel 18b that terminates at its axially forward end at neck l2d and does not extend over a medial region of face 13 towards axis 19.
• the skirt 12 comprises an axial length, centred on axis 19 and extending between a neck l2d (representing an axially rearwardmost region of shoulder 16) and an axially rearwardmost end l2e of skirt 12.
• skirt 12 may be considered to be divided into a number of axial sections defined by the maximum external diameter of the skirt 12 (within each section).
• a first section l2a immediately axially rearward of neck l2d, comprises a smallest diameter;
• a second middle section l2b is radially enlarged relative to first section l2a and an axially rearwardmost third section l2c is radially enlarged relative to the first and second sections l2a, l2b.
• Respective annular step regions 29 provide a transition between the different diameter sections l2a, l2b, l2c.
• Each of the channels l2a, l2b along the length of skirt 12 between neck l2d and rearward end l2e are defined (i.e., flanked) by axially extending ribs indicated generally by reference 17. That is, ribs 17 extend the full length of skirt 12 from head 11 to skirt rearward end l2e. A thickness in the circumferential direction of each rib 17 is non- uniform and changes in a direction of axis 19 between neck l2d and skirt rearward end l2e. Moreover, each rib 17 is curved (alternatively termed angled or bent) in its lengthwise direction between neck l2d and skirt rearward end l2e so as to deviate or deflect in the circumferential direction.
• each of the ribs 17 is bent within the rearward second and third sections l2b, l2c but are substantially linear within the axially forward section l2a immediately behind head 11. Accordingly, channels l8a, 18b are also bent (alternatively termed angled or curved) so as to deviate in the circumferential direction within the second and third sections l2b, l2c.
• ribs 17 and channels l8a, 18b (within sections l2b, l2c) follow a part helical path around axis 19 between a rearward end of first section l2a and skirt rearward end l2e.
• an angle Q by which each rib 17 is bent or deflected in its lengthwise direction from axis 19 may be in the range 1 to 20°, 3 to 10° or 3 to 8°.
• Such deviation refers to the general lengthwise path of ribs 17 within the second and third sections l2b, l2c.
• the combined rearward sections l2b, l2c represents a majority of the length of skirt 12 as each section l2a, l2b, l2c represents generally a respective third of the length of skirt 12.
• An axial length over which the ribs 17 (and channels l8a, 18b) are oblique relative to axis 19 may be in the range 20-100%, 30-90%, 40-80% or 50-70%.
• each rib 17 and channel l8a, 18b may be defined further to include a radially innermost trough 22 which in the lengthwise direction is flanked at a first side by a leading face 20 and an opposite side by a trailing face 25. Faces 20, 25 are so named with reference to the rotational direction R (figure 4).
• Each rib 17 comprises a land face 23 representing a radially outermost region of skirt 12 within each section l2a, l2b, l2c.
• the land face 23 is terminated at each side (in a circumferential direction around axis 19) by a leading edge 21 at the junction with leading face 20 and a trailing edge 24 at the junction with trailing face 25.
• each rib 17 and channel l8a, 18b extends oblique to axis 19 may be defined relative to the general lengthwise pathway of the ribs 17 and channels l8a, 18b or with reference to the relative orientation of trough 22, leading faces 20, leading edge 21, land face 23, trailing edge 24 and/or trailing face 25. According to the specific
• trailing edge 24 is bent at a greater angle relative to leading edge 21 such that a thickness in the circumferential direction of each rib 17 decreases in the axially rearward direction towards skirt rearward end l2e over second and third sections l2b, l2c. Accordingly, a width in the circumferential direction of each channel l8a, 18b increases in the axially rearward direction over sections l2b, l2c.
• a radius of the leading edge 21 may be greater than a corresponding radius of trailing edge 24 so as to provide a corresponding non parallel alignment of leading face 20 and trailing face 25.
• leading face 20 comprises at least a radially outer portion that is aligned on a radial spoke 30 and normal to the rotational direction R so as to be aligned perpendicular to a tangent of an imaginary circle centred on axis 19. Trailing face 25 is aligned transverse to spoke 30 and leading face 20 so as to be declined radially inward from land face 23.
• each of the ribs 17 and channels l8a, 18b at least within the second and third sections l2b, l2c is advantageous to facilitate axially rearward transport of cuttings mixed with the flushing fluid that is typically represented as a sludge. That is, the angled or curved lengthwise orientation of ribs 17 and channels l8a, 18b, facilitate the rearward passage of the sludge from the cutting region at head 11 and axially rearward along the as-formed bore. Additionally, the oblique alignment of ribs 17 and channels l8a, 18b facilitate axially rearward extraction of the drill bit 10 that is also rotated in direction R during extraction. Removing cut debris and flushing fluid from around the external region of the skirt 12 and at the head 11 reduces the risk of the drill bit 10 getting stuck within the bore during extraction in addition to minimising possible bore collapse during extraction.
• the curved or angled lengthwise deviation of ribs 17 and channels l8a, 18b may extend the full axial length of skirt 12 between neck l2d and rearward end l2e.
• the angle by which each rib 17 is aligned relative to axis 19 may the same for all ribs 17 and at all regions of each rib 17 or the angle of deviation may be different for different ribs 17 and at different regions of each rib 17.
• a width of each channel l8a, 18b may be the same between neck l2d and skirt rearward end l2e or may vary in a lengthwise direction.

Landscapes

• Engineering & Computer Science (AREA)
• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Earth Drilling (AREA)
• Percussive Tools And Related Accessories (AREA)
• Processing Of Stones Or Stones Resemblance Materials (AREA)
• Drilling Tools (AREA)

Priority Applications (10)

Applications Claiming Priority (2)

Publications (1)

Family

ID=63449319

Family Applications (1)

Country Status (14)

Cited By (1)

Citations (5)

Family Cites Families (4)

• 2018
  • 2018-08-30 EP EP18191621.4A patent/EP3617439B1/en active Active
  • 2018-08-30 PL PL18191621T patent/PL3617439T3/pl unknown
• 2019
  • 2019-08-15 AU AU2019328385A patent/AU2019328385A1/en not_active Abandoned
  • 2019-08-15 US US17/271,143 patent/US20210238927A1/en not_active Abandoned
  • 2019-08-15 CA CA3107849A patent/CA3107849A1/en active Pending
  • 2019-08-15 WO PCT/EP2019/071966 patent/WO2020043504A1/en active Application Filing
  • 2019-08-15 MX MX2021002224A patent/MX2021002224A/es unknown
  • 2019-08-15 CN CN201980055325.0A patent/CN112585333A/zh active Pending
  • 2019-08-15 BR BR112021003320-3A patent/BR112021003320A2/pt unknown
  • 2019-08-15 KR KR1020217005480A patent/KR20210049810A/ko not_active Application Discontinuation
  • 2019-08-15 JP JP2021510736A patent/JP2021535299A/ja not_active Withdrawn
  • 2019-08-15 PE PE2021000137A patent/PE20211613A1/es unknown
• 2021
  • 2021-01-29 ZA ZA2021/00662A patent/ZA202100662B/en unknown
  • 2021-02-24 CL CL2021000465A patent/CL2021000465A1/es unknown

Patent Citations (5)

Also Published As

Similar Documents

Legal Events