EP4222338A1 - Low stress cavity for conically connecting drill bits - Google Patents
Low stress cavity for conically connecting drill bitsInfo
- Publication number
- EP4222338A1 EP4222338A1 EP21786208.5A EP21786208A EP4222338A1 EP 4222338 A1 EP4222338 A1 EP 4222338A1 EP 21786208 A EP21786208 A EP 21786208A EP 4222338 A1 EP4222338 A1 EP 4222338A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- region
- section
- connection
- drill bit
- curved
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
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
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/02—Couplings; joints
- E21B17/04—Couplings; joints between rod or the like and bit or between rod and rod or the like
-
- 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
- E21B1/00—Percussion drilling
Definitions
- the present invention relates to a rock drill and, more particularly, to a rock drill for use in percussion rock drilling comprising a drill bit having a first conical surface adapted for connection to a drill rod having a corresponding second conical surface.
- drill bits are connected to a drill rod by means on a threaded connection or conical frictional connection.
- the drill bit In the case of the conical frictional connection, otherwise known as a taper joint, the drill bit has a generally conical cavity which is terminated by a cup-shaped cylindrical region, while the end of the drill rod that should be received in the cavity is generally conical.
- the problem to be solved is how to reduce stress in the cavity of the drill bit.
- a percussive drill bit comprising a sleeve section and bit section having a longitudinal axis; wherein the sleeve section has an axial end at the opposing end of the drill bit compared to the bit section from which a generally conically shaped internal cavity extends from for receiving a conically shaped drill rod to form a conical frictional connection; wherein the cavity has a conical region nearest to the axial end and a cylindrical region nearest to the bit section; characterised in that: there is connection section joining the conical region to the cylindrical region; the conical region has a straight tapered region having a starting point adjacent to the connection region; wherein the connection section has at a first curved connection region having a first radius, CRi, wherein its tangent, CTi, to a central point along the first curved connection region
- the inclusion of the curved transition section reduces the stress in the conical cavity of the drill bit. This means the drill bit is less likely to fracture, which reduces the risk of the frictional connection being loosened. Consequently, the lifetime of the drill bit is increased, the risk of the bit spinning with respect to the drill rod or becoming detached from the drill rod is reduced.
- connection section additionally has a second curved connection region having a second radius, CR2, wherein its tangent, CT2, to a central point along the second curved connection region is positioned at a second distance, CD2, from the taper region starting point; wherein CD2 ⁇ CDi and CR2 > CRi.
- the inclusion of two different radii provides a reduction in stress whilst maintaining sufficient contact between the conical rod and the conical cavity in the drill bit.
- CRi is between 1 - 160 mm, more preferably between 5 - 120 mm.
- this provides an optimal balance between providing a tight connection between the conical rod and the conical cavity of the drill bit and achieving a reduction in stress.
- the first curved connection region connects directly to the second curved connection region.
- this design has low levels of the stress in the region of the exit of the conical cavity of the drill bit.
- the first curved region connects to the second curved region via an intermediate straight section.
- this design has low levels of the stress in the region of the exit of the conical cavity of the drill bit.
- connection section further comprises a third curved connection region having a having a third radius, CR3, wherein its tangent, CT3, to a central point along the third curved connection section is positioned at a third distance, CD3, from the taper region starting point, wherein CD3 ⁇ CD2 and CR3 > CR2.
- this design has low levels of the stress in the region of the exit of the conical cavity of the drill bit.
- Figure 1 Cross section of a drill bit having a conically shaped internal cavity.
- Figure 2 Enlargement of the cross section of the connection section according to one embodiment wherein the connection section has a single radius.
- Figure 3 Enlargement of the cross section of the connection section according to one embodiment wherein the connection section has two radii wherein the first curved connection region and the second curved connection region are directly connected.
- Figure 4 Cross section of the connection section according to one embodiment wherein the connection section has two radii wherein the first curved connection region and the second curved connection region of the connection section are connected via an intermediate straight section.
- Figure 5 Enlargement of the cross section of the connection section according to one embodiment wherein there is additionally a third curved connection region in the connection section.
- Figure 6 Cross section of the connection section according to one embodiment wherein there is additionally a curved transition section between the straight tapered region and the cylindrical region.
- Figure 7 Stress image of the conical region of the prior art drill bit.
- Figure 8 Stress image of the conical region of an inventive drill bit.
- Figure 1 shows a cross section of a drill bit 2 comprising a sleeve section 4 and a bit section 6 which are integrated together.
- the sleeve section 4 has an internal cavity 8, having a generally conical shape, for receiving a conically shaped drill rod (not shown).
- the drill bit 2 has a longitudinal axis 30.
- the cavity 8 opens from an axial end 18 of the drill bit 2, furthest from the bit section 6.
- the cavity 8 has the largest cross-sectional diameter at the axial end 18 of the drill bit 2.
- the cavity 8 comprises a conical region 14 that tapers inwardly from the open axial end 18 along a straight tapered region 26 to a cup-shaped cylindrical region 16 that terminates the cavity 8 and is positioned adjacent to the bit section 6.
- a connection section 40 joins the conical region 14 to the cylindrical region 16.
- the tapered region 26 has a taper region starting point 48 adjacent to the connection section 40.
- Figure 2 shows an enlargement of the drill bit 2 in the area of the connection section 40 according to one embodiment of the present invention.
- the internal surface 10 of the connection section 40 has a first curved connection region 42 having a first radius, CRi, wherein its tangent CTi to a central point along the first curved connection region 42 is positioned at a first distance, CDi, from the taper region starting point 48.
- Figure 3 shows an alternative embodiment wherein the internal surface 10 of the connection section 40 has a first curved connection region 42 having a first radius, CRi, wherein its tangent CTi to a central point along the first curved connection region 42 is positioned at a first distance, CDi, from the taper region starting point 48 and a second curved connection region 44 having a second radius, CR2, wherein its tangent CT2 to a central point along the second curved connection section 44 is positioned a second distance, CD2, from the taper region starting point 48.
- CD2 ⁇ CDi and CR2 > CRi in other words the curved connection section having the smaller radius is adjacent to the cylindrical region 16.
- CRi is between 1-160 mm, preferably between 5-120 mm.
- CR2 is between >1 - 160 mm, preferably between 5 - 120 mm.
- the first curved connection region 42 is directly connected to the second curved connection region 44 and the second connection region 44 is directly connected to the straight tapered region 26.
- Figure 4 shows an alternative embodiment, wherein the first curved connection region 42 is connected to the second curved connection region 44 via an intermediate straight section 34.
- connection section 40 additionally comprises a third curved connection region 46.
- the third curved connection region 46 has a third radius, CR3, wherein its tangent, CT3, to a central point along the first curved connection region 46 is positioned at a third distance, CD3, from taper region start point 48, wherein CD3 ⁇ CD2.
- CR3 will be different to CRi and CR2, preferably CR3 > CR2.
- the connection section 40 could also comprise more than three curved connection sections, each having a different radius. Each of the curved connection sections could either be directly connected to each other could be connected to each other via an intermediate straight section 34.
- Figure 6 shows an alternative embodiment wherein there is additionally a curved transition section 32 that is positioned in-between the axial end 18 of the drill bit 2 and the straight tapered region 26.
- Figure 7 shows the von Mises equivalent stress taken of the conical region 14 of a prior art drill bit, wherein there is no curved connection region.
- Figure 8 shows the von Mises equivalent stress taken of the conical region 14 for an inventive drill bit, wherein there is a first curved connection region.
- one rod and one bit are included and the models are axi-symmetry.
- An axial load of 190 kN is applied on the end of the rod and the bit face is fully supported.
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)
Abstract
Description
Claims
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP20199285.6A EP3978720A1 (en) | 2020-09-30 | 2020-09-30 | Low stress cavity for conically connecting drill bits |
| PCT/EP2021/076976 WO2022069653A1 (en) | 2020-09-30 | 2021-09-30 | Low stress cavity for conically connecting drill bits |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP4222338A1 true EP4222338A1 (en) | 2023-08-09 |
| EP4222338B1 EP4222338B1 (en) | 2025-09-10 |
Family
ID=72709117
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP20199285.6A Withdrawn EP3978720A1 (en) | 2020-09-30 | 2020-09-30 | Low stress cavity for conically connecting drill bits |
| EP21786208.5A Active EP4222338B1 (en) | 2020-09-30 | 2021-09-30 | Low stress cavity for conically connecting drill bits |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP20199285.6A Withdrawn EP3978720A1 (en) | 2020-09-30 | 2020-09-30 | Low stress cavity for conically connecting drill bits |
Country Status (3)
| Country | Link |
|---|---|
| EP (2) | EP3978720A1 (en) |
| JP (1) | JP7760584B2 (en) |
| WO (1) | WO2022069653A1 (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB658631A (en) | 1949-01-01 | 1951-10-10 | Hall & Pickles Ltd | Improvements in percussive drill bits |
| GB860768A (en) | 1958-04-04 | 1961-02-08 | Electrochimie Electrometallurg | Improvements in or relating to a method of manufacturing rock and like drills and tosuch drills |
| US3336081A (en) * | 1965-08-02 | 1967-08-15 | Samuel S Ericsson | Percussion tool with replaceable point |
| US5685381A (en) * | 1995-07-21 | 1997-11-11 | Kennametal South Africa (Proprietary) Limited | Drill rod and drill bit with rocking connection |
| DE29519484U1 (en) * | 1995-12-08 | 1996-01-25 | Drebo Werkzeugfabrik Gmbh, 88361 Altshausen | drill |
| SE531412C2 (en) | 2005-12-30 | 2009-03-31 | Sandvik Intellectual Property | Rock drilling tools, rock drill bit and method for manufacturing a conical cavity of a rock drill bit |
| JP7098278B2 (en) | 2016-05-13 | 2022-07-11 | ヘンズリー インダストリーズ,インコーポレイティド | Stabilized specific structure in wear member assembly |
-
2020
- 2020-09-30 EP EP20199285.6A patent/EP3978720A1/en not_active Withdrawn
-
2021
- 2021-09-30 EP EP21786208.5A patent/EP4222338B1/en active Active
- 2021-09-30 JP JP2023519718A patent/JP7760584B2/en active Active
- 2021-09-30 WO PCT/EP2021/076976 patent/WO2022069653A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| EP4222338B1 (en) | 2025-09-10 |
| JP2023543852A (en) | 2023-10-18 |
| JP7760584B2 (en) | 2025-10-27 |
| WO2022069653A1 (en) | 2022-04-07 |
| EP3978720A1 (en) | 2022-04-06 |
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