(19) |
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EP 2 339 109 B1 |
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EUROPEAN PATENT SPECIFICATION |
(45) |
Mention of the grant of the patent: |
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20.12.2017 Bulletin 2017/51 |
(22) |
Date of filing: 22.12.2010 |
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(51) |
International Patent Classification (IPC):
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(54) |
Earth drilling tool and method
Erdbohrwerkzeug und -verfahren
Outil et procédé de forage du sol
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(84) |
Designated Contracting States: |
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AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL
NO PL PT RO RS SE SI SK SM TR |
(30) |
Priority: |
23.12.2009 SE 0951022
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(43) |
Date of publication of application: |
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29.06.2011 Bulletin 2011/26 |
(73) |
Proprietor: Lövab Aktiebolag |
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68592 Torsby (SE) |
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(72) |
Inventor: |
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- Löf, Jan-Åke
685 92 Torsby (SE)
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(74) |
Representative: Johansson, Lars E. |
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P.O. Box 138 683 23 Hagfors 683 23 Hagfors (SE) |
(56) |
References cited: :
WO-A1-91/12406 WO-A1-2005/098194
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WO-A1-03/004824
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
|
FIELD OF THE INVENTION
[0001] The present invention relates to a drilling tool for down-the-hole drilling, which
drilling tool is intended to drill a hole ahead of a following casing tube, the drilling
tool comprising a drill assembly which comprises a central pilot drill bit portion,
a peripheral ring shaped drill bit portion and a coupling device, said assembly being
coupled to a drill string.
BACKGROUND INFORMATION
[0002] Drilling tools for down the hole drilling are previously known that comprise an assembly
of parts forming a central drill bit portion, i.e. a central reusable drill bit portion
with a pilot drill, a peripheral ring shaped drill bit portion and a ring shaped coupling
device. When a hole is done the peripheral ring shaped drill bit portion and the ring
shaped coupling device are left in the drill hole whereas the central pilot drill
bit portion is retracted from the hole together with the drill string and can be reused.
Known types of drilling tools are seen in
EP1402146,
US4773489,
US5803192 and
WO9534740.
[0003] Depending on the type of ground to be drilled (e.g. soft, medium or hard formation
rock) different drill bit portions of various types are used. The size of the pilot
drill bit portion is also varied depending on the desired diameter of the hole to
be drilled. For each new circumstance the drill bit portion is switched into one that
meets the new requirements, which may often be a time consuming process. If the drill
bit portion is worn out it is disposed of and replaced by a new central drill bit
portion. This leads to considerable waste of material which is undesirable both from
an economical and environmental point of view.
[0004] Another problem related to presently known drilling tools is that production of the
large and heavy drill bit portions is associated with a laborious and uneconomical
production process. Often an initial large piece of steel material is cut in a metalworking
lathe into a desired shape, which often leads to loss of material. During production
of drill bit portions it is not uncommon that an initial steel block is reduced from
a thickness of 800 mm to a final diameter of 100 mm, meaning a substantial amount
of cut away steel is merely thrown as waste.
OBJECTS OF THE INVENTION
[0005] It is an object of the present invention to overcome or at least minimize at least
one of the drawbacks and disadvantages of the above described known drilling tools.
[0006] A first object of the present invention is to be able to easily exchange the central
drill bit portion so that the same drive shaft may be provided with a new pilot drill
bit portion whereas the drive shaft itself is reused. This will lead to a number of
advantages, such as
- reduced material consumption (i.e. only the actual pilot drill portion of the drilling
tool which is subject to wear and tear is exchanged while the drive shaft is reused),
- the possibility of easily switching between differently dimensioned pilot drill portions
enabling for quick adjustments of the equipment for drilling different types of holes
and different types of ground (e.g. soft, medium or hard formation rock),
- easier manufacturing of the drilling tool due to that the smaller units of the invented
tool can be produced with less material consumption compared to production of one
large central drill bit portion as is known prior art,
- easier maintenance due to smaller and less heavy parts.
[0007] This and other objects, which are obvious to the expert, have been able to be realized
in a surprising manner by designing the drilling tool in accordance with the characterizing
part of claim 1. Preferred embodiments of the invented drilling tool are defined in
the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will be described in more detail with reference to the enclosed figures,
in which:
- Fig. 1A
- is an elevational view of the lower portion of a drilling tool according to one embodiment
of the invention,
- Fig. 1B
- is a vertical cross sectional view of the lower portion of the drilling tool shown
in Fig. 1A,
- Fig. 2
- is an exploded view showing a drilling tool according to one embodiment of the invention,
- Fig. 3
- is a perspective view showing the central pilot drill bit portion according to one
embodiment of the invention,
- Figs. 4A-C
- show different views of the central pilot drill bit portion shown in Fig. 3,
- Fig. 5
- is a perspective view showing the blast protection ring according to one embodiment
of the invention,
- Fig. 6
- is a perspective view showing the drill shaft according the one embodiment of the
invention,
- Figs. 7A-B
- show different views of the casing shoe according to one embodiment of the invention,
- Fig. 8A
- is a perspective view showing the drill shaft according the another embodiment of
the invention,
- Fig. 8B
- shows an end view of the drill shaft shown in Fig. 8A,
- Fig. 9A
- is a perspective view showing a central pilot drill bit portion according to another
embodiment of the invention, and
- Fig. 9B
- is a cross sectional view of the central pilot drill bit portion in Fig. 9A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] The foregoing aspects and many of the attendant advantages of this invention will
become more readily appreciated as the same become better understood by reference
to the following detailed description, when taken in conjunction with the accompanying
drawings. Further, the description, and the examples contained therein, are provided
for the purpose of describing and illustrating certain embodiments of the invention
only and are not intended to limit the scope of the invention in any way.
[0010] In Figs. 1 and 2 is shown the drilling tool according to one embodiment of the invention.
The shown drilling tool is intended for down-the-hole drilling, wherein a hole is
drilled ahead of a following casing tube 13. As is known per se a chuck 12 is coupled
to a continuous drill string (not shown), via a hammer unit (not shown) in a casing
tube 13, by means of which a drill assembly 10 rotates clockwise in the embodiment
illustrated and receives percussion energy from the hammer unit. The drill assembly
10 can be assigned percussion energy via a down-the-hole hammer (not shown) or a left-rotating
top-hammer coupled in a torsionally rigid manner (not shown). The drill string, hammer
unit and their parts are of a conventional type and are not shown in the figures.
[0011] The drilling tool 1 comprises a drill assembly 10 which has a central, reusable pilot
drill bit portion 2, a peripheral ring shaped disposable ring drill bit portion 4
and a disposable coupling device 3 in the form of a casing shoe. The casing shoe 3
is fixed to the casing tube 13 by means of welding 5 (as in known per se). The ring
drill bit portion 4 has external threads 45 at the top sides which are used to thread
it into the casing shoe 3, past the threads on the casing shoe 3, to allow the ring
drill bit portion 4 some axial play between the threads 35 and an intermediate edge
36. According to the invention the said assembly 10 is coupled to the drill string,
via the chuck 12 , which in turn via internal splines 121 transfer torque to a drive
shaft device 9 (via mating splines 98), which releasably interfits with the pilot
drill bit portion 2 for transmitting torque from the drill string to the drill assembly
10. (Also the top flange 97 of the drive shaft device has splines to allow the chuck
12 to be moved onto it from above.)
[0012] The drive shaft device 9 interfits with the pilot drill bit portion 2 via a central
hole 22 within the pilot drill bit portion 2, as will be explained more in detail
below. Around the upper part 91 of said drive shaft 9 there is mounted the chuck 12,
which in its turn is resting on a ring shaped blast protection unit 15. The blast
protection ring 15 is interposed between the chuck 12 and the central pilot drill
bit portion 2. As is known per se the chuck 12 is arranged with outer threads and
an edge 121 for interfit with the casing of the hammer (not shown). The blows from
the hammer hit on the top 99 of the drive shaft device 9 . The chuck 12 is arranged
to axially slide along the splines 98 and also as a concequence along the cylindrical
surface of the drive shaft below the splines 98. As known per se coupling halves (not
shown), blocked by the upper edge 97 keep the chuck 12 safely in place together with
the drive shaft device 9.
[0013] As is common knowledge, upon drilling a flushing medium (such as pressurized air)
is supplied through the central through hole 94 of the shaft 9 and further via flushing
channels 26, 26' within the pilot drill bit portion 2. Any by drilling loosened matter/gravel
is activated by the onset of flushing medium and is removed from the drill hole through
longitudinal flushing grooves 21 (see Fig. 3-4) on the outer side of the pilot drill
bit portion 2. This results in a blasting stream of drilled loose matter which exits
flushing grooves 21 in an upward direction. According to the invention said blast
protecting ring 15 is positioned adjacent to the opening of the flushing grooves 21
so that the blasted matter will hit the surface of said ring 15 instead of hitting
the guide body 12 thus protecting it from wear which is advantageous since the guide
body 12 is made of a more expensive material compared to the ring 15 unit. Preferably
the blast protecting ring 15 is made of a hardened steel material which will resist
the heavy onset of blasting matter/gravel. When worn out the ring 15 is very easily
exchanged into a new one. As is seen in Fig. 1B the ring 15 preferably has a tapered
cross section with a narrow base abutting the top part of the pilot drill bit portion
2 and the wider portion abutting the guide body 12. The tapered shape leads to that
the flushed matter/gravel is guided outwards and upwards and is transported along
the inner walls of the casing tube 13.
[0014] The releasable connection between the drive shaft 9 and the pilot drill bit portion
2 is preferably achieved in two ways cooperating with each other. First in that a
number of connecting bits 16 torsionally interconnect the two units 2, 9, and second
in that at least one locking ball 250 is positioned within circumferential recesses
25, 95 preventing the drive shaft 9 from being retracted out of the central hole 22
(see Fig. 3) of the pilot drill bit portion 2. The connection between the drive shaft
9 and the pilot drill bit portion 2 will be described in more detail in connection
to Fig. 2, Fig. 4B and Fig. 8 - 9. The second axial coupling may be achieved in other
ways than by means of a locking ball, for instance by means of a locking pin or the
like preventing axial retraction.
[0015] The present design of a drilling tool 1 leads to that only the pilot drill bit portion
2 may be exchanged by reusing the same drive shaft device 9, which provides many advantages,
e.g. cost advantages (smaller part leads to less material and easier production) and
easier maintenance. Thanks to the invention it is possible to use modular design and
subdivide the components of a drilling tool into modular units which may be combined
in a highly flexible way into a desired drilling tool 1. This also leads to less heavy
exchange part and easier accessible releasable connection.
[0016] Fig. 2 shows an exploded view of one embodiment according to the invention. The drive
shaft 9 has an upper 91 and a lower 92 portion, where the lower portion is intended
to be introduced into the central hole 22 (see Fig. 3) of the pilot drill bit portion
2. At the lower portion 92 the drive shaft is provided with a number of longitudinal
recesses 93, preferably three outer recesses 93, which are symmetrically arranged
around the outer surface of the drive shaft 9. Each recess matches a removable connecting
bit 16. As is shown in Fig. 3 the central hole 22 of the pilot drill bit portion 2
comprises a number of inner recesses 23, preferably the same number of inner recesses
23 as there are outer recesses 93 within the drive shaft 9, that is, in the embodiment
of Fig. 2 and 3 a number of three. The skilled person understands that the number
of connecting bits 16 and inner recesses 23 respectively can be more than three, depending
on the required torque momentum transmission of a particular drilling assembly 1.
For larger drilling assemblies as many as twelve connecting bits 16 may be necessary
in order to achieve a strong enough torque transmitting coupling, whereas for medium
type assemblies six or eight may be enough.
[0017] The coupling of a drive shaft 9 and a pilot drill bit portion 2 is now to be described.
A connecting bit 16 is positioned within each of said recesses 93 so that each bit
16 is partly projecting radially out from the drive shaft 9. Preferably the arrangement
according to the invention 1 comprises retaining means or a retaining mechanism for
at least temporarily retaining the connecting bits 16 within the matching recesses
93 of the drive shaft 9. Thus when disconnecting the drive shaft 9 from a pilot drill
bit portion 2 the connecting bits 16 will remain positioned within the recessed until
being removed, which may for instance be done manually. Retaining of the connecting
bits 16 may be achieved in many different ways, for example with of one or more O-rings
being introduced around the plurality of connecting bits 16 keeping them in place.
It is also possible to provide some sort of mechanical formfitting between the connecting
bits 16 and the recesses 93, for instance matching protrusions and grooves, having
an engaging effect. The drive shaft 9 is introduced into the central hole 22 of the
pilot drill bit portion 2. Upon introduction of the drive shaft 9 the protruding connecting
bits 16 are positioned to slide into the inner recesses 23 resulting in a torsional
connection/coupling between the drive shaft 9 and the pilot drill bit portion 2. According
to a preferred aspect of the invention the outer surface of each of the connecting
bits 16 is arranged with an outer radius, and in a corresponding manner each of said
inner recesses 23 has an inner radius mating the outer radius of said connecting bit
16. The radial mating surfaces of the connecting bits 16 and the inner recesses 23
respectively leads to a firm connection between the drive shaft 9 and the drill bit
portion 2 where torque is transmitted from the drive shaft 9 to the drill bit 2 over
the entire radius of the connecting bit 16, leading to a very effective transfer of
forces and also to a significantly improved mechanical sustainability compared to
known drilling tools.
[0018] A benefit of the releasable connecting bits 16 is that they are easily replaceable
when worn out, leading to that by means of just shifting minor components of the connection
its lifetime may be extended thus postponing the need for replacing the whole drive
shaft 9, which obviously is expensive and leads to undesired waste of materials.
[0019] The drive shaft 9 further comprises an outer circumferential recess 95. Upon introduction
of the drive shaft 9 into the central hole 22 of the pilot drill bit portion 2 the
outer recess 95 is arranged to be positioned to face an inner circumferential recess
25 within the central hole 22 of the pilot drill bit portion 2 (see Fig. 4B) thus
jointly creating a kind of inner annular groove 25, 95. In order to lock the drive
shaft 9 and the pilot drill bit portion 2 in an axial direction one or more locking
balls 250 are put through a radial bore inlet 251 within the drill bit portion 2,
leading to the circumferential groove 25, 95, which allows the balls 250 to interconnect
the drive shaft 9 and the pilot drill bit portion 2 in the axial direction, but with
some play to not cause damage to the balls 250 upon blows from the hammer. After supply
of the balls 250 the inlet 251 is arranged with a releasable plug (not shown) that
extends into the periphery of the recess 25 to safety position the balls 250 within
the groove 25, 95.
[0020] A particular advantage provided by the present invention relates to that threaded
connections between the releasable components 2, 4; 2, 9 of the drilling tool 1 are
essentially avoided. Threaded connections are often very hard to release after a drilling
operation, whereas the couplings according to the invention on the contrary are quite
easy to loosen.
[0021] Fig. 3 shows a perspective view of a pilot drill bit portion 2 according to one embodiment
of the invention with said central hole 22 and inner recesses 23 dimensioned to match
the connecting bits 16. The pilot drill bit portion 2 is further provided with a number
(here three) of outer flushing grooves 21 which function as transporting channels
for drilled matter and gravel out of the drilled hole. The lower part of the pilot
drill bit portion 2 comprises protrusions 24 intended for connecting the pilot drill
bit portion 2 to the ring drill bit portion 4 (see Figs. 7A-B).
[0022] According to a preferred embodiment the upper portion of the pilot drill bit portion
2 comprises a first 27 and a second 28 flange which function will be more described
later.
[0023] Referring now to Figs. 4A-B which show the underside, a cross section and the upper
side of a pilot drill bit portion 2 respectively. The lower drill surface 29 has openings
of said flushing channels 26, the diameter of which is adapted to the desired flushing
medium and/or flow quantity. As is clear from Fig. 4B a first 27 and a second flange
28 are arranged at the upper part of the pilot drill bit portion 2 resulting in a
first 270 and a second meeting edge 280. These edges assist in transferring the percussion
energy that via the top 99 is transferred to the bottom 97 of the drive shaft device
9 and there from partly transferred to the ring drill bit portion 4 . The task of
the first meeting edge 270 is to abut the top edge 30 of casing shoe 3. Likewise,
the second meeting edge 280 is intended to meet and abut a inner top edge 443 of the
ring drill bit portion 4 (as is also seen in Fig. 1B). During drilling operation the
described design with double flanges 27, 28 on the pilot drill bit portion 2 leads
to the advantage of substantially reduced wear on the equipment compared to a design
with one flange, since percussion energy is absorbed by two pairs of meeting edges
instead of one. Hence, the percussion energy will first be transferred to the central
drill bit portion 2, some of which will directly act at its drill face 29, and some
that via first edge 270, further via its intermediate edge 36 to an outer top edge
42 of the ring drill bit portion 4, and further some that via the second edge 280
will be transferred to the inner top edge 43 of the ring drill bit portion 4.
[0024] Hence, percussion energy is transferred from the drill bit portion 2 to the ring
drill bit portion 4 at two radially off-set positions/edges 42, 43. Accordingly in
total a large transfer area is obtained, which is even increased by having tapered
mating surfaces 43/280; 42/36.
[0025] Another beneficial aspect of the invention is that the design of the assembly 10
(i.e. the meeting surfaces) results in that the backward recoil energy created during
drilling operation will be effectively absorbed by the components of the drill assembly
10. Upon kickback, recoil energy will be transferred from the pilot drill bit portion
2 via the connecting protrusions 24 to the casing shoe 4, and there from to the lower
end surface 36 of the ring bit portion 3. Also this design will lead to substantially
reduced wear and tear on the drilling tools.
[0026] As is seen in the cross sectional view in Fig. 4B there is a radial bore 251 for
the locking balls 250, adapted to the diameter of the radial recess 25.
[0027] For clarifying reasons are provided Figs. 5 and 6 showing perspective views of the
blast protecting ring 15 and the drive shaft device 9 respectively. The blast protecting
ring 15 is tapered with a lower narrow end 150 and a wider upper end 151, where the
diameter of the wider end preferably corresponds to the outer diameter of the lower
end of the chuck 12.
[0028] The perspective view of the drive shaft device 9 further shows the central flushing
channel 94 intended for flushing of medium.
[0029] In Figs. 7A-B are seen the ring drill bit portion 4 according to a preferred embodiment.
When shown from above, as in Fig. 7A, it is seen that the ring drill bit portion 4
comprises a number of connecting grooves 40 which matches the connection protrusions
24 of the pilot drill bit portion 2. The protrusions 24 are introduced into the grooves
40, until edges 280 and 43 meet, and the parts 2,4 are then turned so that relative
to each other the protrusions 24 are fit into a recess 44 arranged at the bottom of
each groove 40. Here the recesses 44 are positioned for right-hand rotation (seen
from above) intended for the protrusions 24. In case of a drilling tool with a left-hand
rotation the recesses 44 shall be positioned in a mirror-image position compared to
Fig. 7A. When the drilling operation is completed the drill string is turned the opposite
direction, so that the protrusions 24 of the pilot drill bit portion 2 are released/moved
out from the recesses 44, whereby the drill string with shaft device 9 and pilot drill
bit portion 2 is free to lift upwards from the ring drill bit portion 4 which is left
in the drilled hole together with said casing shoe 3.
[0030] In Fig. 8A - B is shown a drive shaft device 9 according to another embodiment of
the invention. In Fig. 8A, showing a perspective view of a drive shaft 9, there is
seen that the component has a first upper end 91 and a second lower end 92, whereat
in said upper end 91 there is arranged a top flange 97 arranged to keep the chuck
12 safely in place together with the drive shaft device 9. A protruding flange 920
ensures that the drill shaft 9 when connected to a drill bit portion 2 is introduced
into the drill bit portion 2 to the right extent and is positioned correctly in order
for the outer recess 95 and the inner circumferential recess 25 within the central
hole 22 of the pilot drill bit portion to meet and jointly creating a kind of inner
annular groove 25, 95.
The embodiment seen in Fig. 8A comprises in its lower end 92 a plurality of elongated
connecting members 96 fixedly arranged onto and forming an integrated part of the
drive shaft device 9. The connecting members 96 may be fixedly attached onto the drive
shaft 9 or they may be cut out during the production of the drive shaft 9. Each of
the connecting members 96 is formed with an outer radius, similar to the releasable
connecting bits 16 previously described, and are arranged to match with inner recesses
23 of a mating drill bit portion 2 (see Fig. 9A - B).
[0031] In Fig. 8B there is shown an end view of the drill shaft 9 of Fig. 8A, exposing the
central through hole 94. Herein is seen the plurality of connecting members 96 circumferentially
distributed around the lower end 92 of a drill shaft 9. Preferably the connecting
members 96 are evenly positioned around the circumference of the shaft 9 in order
to achieve a balanced torque transmission upon operation. In this example the shaft
9 comprises eight connecting members 96, whereat two neighbouring connecting members
96 are arranged with an angle α in between as is illustrated in Fig. 8B. Preferably
α is the same for all connecting members 96, meaning in this example (i.e. eight members
96) α equals 45°. However other numbers of connecting members 96 are also possible
meaning that also angle α will vary. For larger drilling equipment (i.e. larger pilot
drill bits 2) as many as twelve connecting members 96 might be necessary for attaining
enough strength in the torque coupling, whereas a lesser number may suffice for smaller
drilling assemblies 10.
[0032] The drilling assembly 10 according to the invention may be used for a variety of
sizes of drilling equipment. Fig. 8B shows the diameter D of the lower end 92 of the
drill shaft 9. The diameter D may be between 50 - 250 mm depending on the size of
the pilot drill bit portion 2 to be coupled to the drill shaft 9. The size of the
pilot drill bit portion 2 will determine the size of the hole to be drilled, and the
drill bit portion 2 in its turn must be adapted to the size of the casing tube 13.
An advantageous aspect of the present invention is that one type of drill shaft 9
can be used for connecting many different types (e.g. sizes) of pilot drill bit portions
2, meaning that the drilling equipment is easily and quickly adapted to different
types of drilling operations (e.g. in order to handle different typed of holes and
different types of grounds respectively). By also being able to exchange the pilot
drill bit 9 the assembly 10 according to the invention can cover a wide variety of
different sizes of drilling tools 1, meaning for instance when a certain type of drill
shaft 9 is too small to handle a given drill bit portion 2 changing of the shaft 9
into a larger one enables further operation with said drill bit portion 2 (providing
that the casing tube 13 is also compatible, as is obvious to the skilled person).
[0033] In Fig. 9A there is seen a perspective view of a pilot drill bit portion 2 according
to another embodiment of the invention, arranged to mate with and be connected to
a drill shaft 9 as the one shown in Fig. 9A-B. In Fig. 9B there is seen a cross sectional
view along line IXB in Fig. 9A. In a corresponding manner to what's previously been
described the lower end 92 portion of a drill shaft 9 is arranged to be introduced
into the central opening 22 of the drill bit portion 2 to achieve a torque coupling.
Axial coupling is achieved by means of for instance a ball lock arrangement. The inner
recesses 23 of the drill bit portion 2 are arranged with an inner radius mating the
outer radius of said connecting members 96 so that a firm connection between the connecting
members 96 and the inner recesses 23 is achieved resulting in an excellent torque
momentum transmission over the entire radius surface.
[0034] As is well understood by the skilled person the size of the drill bit portion 2 will
determine the size of the hole to be drilled. Various dimensions of drill bits 2 can
be used in a drilling tool 1 according to the invention, and the diameter d of the
drill bits 2 may vary between 90 - 610 mm for different types of drill bits 2. Thanks
to the invention it is possible to rather easily adapt the equipment to handling different
types of drilling, by providing a plurality of central pilot drill bit portions 2
(including at least two different drill bit portions 2) and exchange of one central
drill bit portion 2 to a different kind.
[0035] It is understood that the objects of the present invention set forth above, among
those made apparent by the detailed description, shall be interpreted as illustrative
and not in a limiting sense. Within the scope of the following claims the set-up of
various alterations of the present invention may be possible. For instance, for the
skilled person it is evident that there exist a big variety of different solutions
to achieve the couplings used between the drive shaft device 9 and the pilot drill
bit portion 2, e.g. to achieve the axial coupling, by means of bores and pins (as
known
per se), or plate formed segments fitting into corresponding recesses, etc. Likewise the
releasable torque coupling can be achieved in many different ways, e.g. by the use
of splines, etc. Further it is also feasible to achieve the coupling by having a threaded
connection between the drive shaft device 9 and the pilot drill bit portion 2. Further
it is foreseen that a check valve device 6 (see fig 1) may be used to hinder dirt
(pressurized) to enter into the hammer device during stand still.
1. Drilling tool for down-the-hole drilling, which drilling tool is arranged to drill
a hole ahead of a following casing tube (13), the drilling tool comprising a drill
assembly (10) which comprises a central pilot drill bit (2, 9), a casing shoe (3)
and an outer peripheral ring shaped drill bit portion (3, 4) releasably attached to
said central pilot drill bit (2, 9), said assembly (10) being coupled to a drill string,
characterized in that the central pilot drill bit (2), comprises a central pilot drill bit portion (2)
and a drive shaft device (9) which are arranged to releasably interfit to transmit
torque from the drill string to the drill assembly (10), wherein the drive shaft device
(9) has a lower, shaft formed portion (92), which releasably interfits within a central
hole (22) of the pilot drill bit portion (2) by means of a first coupling arrangement
(16, 96, 23, 93), wherein said shaft formed portion (92) is arranged with connecting
members (16, 96) each comprising an outer radius arranged to mate with inner recesses
(23) within the central hole (22), each recess (23) comprising an inner radius mating
with the outer radius of said connecting members (16, 96), whereby a torque transmitting
coupling is achieved.
2. Drilling tool according to claim 1, wherein said first coupling (16, 23, 93) is arranged
by means of releasable, connecting bits (16) arranged to match recesses (93) around
the periphery of said second end (92), and also to match inner recesses (23) in said
central hole (22), so that upon coupling the rotational movement from the drive shaft
(9) is transmitted to said assembly (10).
3. Drilling tool according to any preceding claim, wherein the drive shaft device (9)
is axially coupled to the central pilot drill bit (2) by means of a second releasable
axial coupling arrangement (25, 95, 250).
4. Drilling tool according to claim 3, wherein said second releasable coupling arrangement
(25, 95, 250) comprises at least one locking ball (250), preferably a number of locking
balls (250), arranged within a circumferential recess (25) within said central hole
(22) of the central pilot drill bit (2) and also a circumferential recess (95) around
the periphery of the drive shaft device (9).
5. Drilling tool according to claim 4, wherein there is arranged a radial bore (251)
in the body of said central pilot drill bit (2) arranged to facilitate supply and
removal of said locking ball/s (250).
6. Drilling tool according to claim 5, wherein the central pilot drill bit portion (2)
comprises a first (27) flange and a second flange (28), wherein said first (27) flange
(27) is arranged to transmit percussion energy to said drill bit portion (2) indirectly
via said casing shoe (3) and said second flange (28) is arranged to transmit percussion
energy directly to said drill bit ring (4).
7. Drilling tool according to any preceding claim, wherein the drilling tool (1) comprises
a chuck (12) arranged to transmit torque from said drill string to said drill assembly
(10).
8. Drilling tool according to claim 7, wherein there is a blast protecting ring (15)
positioned in between the central pilot drill bit portion (2) and the chuck (12).
9. Drilling tool according to claim 8, wherein the blast protecting ring (15) has a tapered
cross section.
10. Drilling tool according to any preceding claim, wherein the central pilot drill bit
portion (2) comprises axially extending flushing grooves (21).
11. Drilling tool assembly comprising a plurality of central pilot drill bit portions
(2) according to any preceding claim, wherein said plurality of central pilot drill
bit portions (2) include at least two different drill bit portions (2) arranged to
handle different types of drilling.
12. Method for assembling a drilling tool comprising the steps of
a. providing a drill assembly (10) with a central pilot drill bit portion (2), a peripheral
ring shaped drill bit portion (4) and a casing shoe (3),
b. providing a casing tube (13) which and a drill string,
c. characterized in
d. further providing a drive shaft device (9) and
e. connecting the drive shaft device (9) to transfer torque from a drill string, and
f. releasably connecting the drive shaft device (9) by means of a torque coupling
(16, 23, 93) to the central drill bit portion (20).
13. Method according to claim 12, further also releasably connecting the drive shaft device
(9) by means of a axial coupling (25, 95, 250) to the central drill bit portion (20).
14. Method according to claim 13, further providing a plurality of central pilot drill
bit portions (2) including at least two different drill bit portions (2) and exchange
of one central drill bit portion (2) to a different kind of drill bit portion (2)
to handle different types of drilling.
15. Method according to claim 14, wherein said exchange is related to handle different
types of holes.
16. Method according to claim 14, wherein said exchange is related to handle different
kind of grounds.
1. Bohrwerkzeug zum Im-Loch-Bohren, wobei das Bohrwerkzeug eingerichtet ist, ein Loch
vor einem nachfolgenden Gehäuserohr (13) zu bohren, wobei das Bohrwerkzeug eine Bohranordnung
(10), welche einen zentralen Pilotbohrmeißel (2, 9) umfasst, einen Gehäuseschuh (3)
und einen äußeren am Rand gelegenen ringförmigen Bohrmeißelabschnitt (3, 4), welcher
lösbar an dem zentralen Pilotbohrmeißel (2, 9) angebracht ist, umfasst, wobei die
Anordnung (10) an einen Bohrstrang gekoppelt ist, dadurch gekennzeichnet, dass der zentrale Pilotbohrmeißel (2) einen zentralen Pilotbohrmeißelabschnitt (2) und
eine Antriebswellenvorrichtung (9) umfasst, welche eingerichtet sind, lösbar zu passen,
um Drehmoment von dem Bohrstrang zu der Bohranordnung (10) zu übertragen, wobei die
Antriebswellenvorrichtung (9) einen unteren, Wellen-förmigen Abschnitt (92) aufweist,
welcher mittels einer ersten Kopplungseinrichtung (16, 96, 23, 93) lösbar in ein zentrales
Loch (22) des Pilotbohrmeißelabschnitts (2) passt, wobei der Wellen-förmige Abschnitt
(92) mit Verbindungelementen (16, 96) eingerichtet ist, wobei jedes einen äußeren
Radius umfasst, der eingerichtet ist, mit inneren Vertiefungen (23) in dem zentralen
Loch (22) zusammenzupassen, wobei jede Vertiefung (23) einen inneren Radius umfasst,
der mit dem äußeren Radius der Verbindungselemente (16, 96) zusammenpasst, wodurch
eine Drehmomentübertragungskopplung erreicht wird.
2. Bohrwerkzeug gemäß Anspruch 1, wobei die erste Kopplung (16, 23, 93) mittels lösbarer
Verbindungseinsätze (16) eingerichtet ist, die eingerichtet sind, Vertiefungen (93)
um den Rand des zweiten Endes (92) zu entsprechen und auch inneren Vertiefungen (23)
in dem zentralen Loch (22) zu entsprechen, so dass nach Koppeln die Drehbewegung von
der Antriebswelle (9) zu der Anordnung (10) übertragen wird.
3. Bohrwerkzeug gemäß einem der vorstehenden Ansprüche, wobei die Antriebswellenvorrichtung
(9) mittels einer zweiten lösbaren axialen Kopplungsanordnung (25, 95, 250) mit dem
zentralen Pilotbohrmeißel (2) axial gekoppelt ist.
4. Bohrwerkzeug gemäß Anspruch 3, wobei die zweite lösbare Kopplungsanordnung (25, 95,
250) mindestens eine Verriegelungskugel (250), bevorzugt eine Anzahl von Verriegelungskugeln
(250), die in einer umlaufenden Vertiefung (25) in dem zentralen Loch (22) des zentralen
Pilotbohrmeißels (2) eingerichtet sind, und auch eine umlaufende Vertiefung (95) um
den Rand der Antriebswellenvorrichtung (9) umfasst.
5. Bohrwerkzeug gemäß Anspruch 4, wobei eine radiale Bohrung (251) in dem Körper des
zentralen Pilotbohrmeißels (2) eingerichtet ist, die eingerichtet ist, Zufuhr und
Entnahme der Verriegelungskugel/n (250) zu erleichtern.
6. Bohrwerkzeug gemäß Anspruch 5, wobei der zentrale Pilotbohrmeißelabschnitt (2) einen
ersten (27) Flansch und einen zweiten Flansch (28) umfasst, wobei der erste (27) Flansch
(27) eingerichtet ist, Schlagenergie zu dem Bohrmeißelabschnitt (2) indirekt über
den Gehäuseschuh (3) zu übertragen, und wobei der zweite Flansch (28) eingerichtet
ist, Schlagenergie direkt zu dem Bohrmeißelring (4) zu übertragen.
7. Bohrwerkzeug gemäß einem der vorstehenden Ansprüche, wobei das Bohrwerkzeug (1) ein
Spannfutter (12) umfasst, das eingerichtet ist, Drehmoment von dem Bohrstrang an die
Bohranordnung (10) zu übertragen.
8. Bohrwerkzeug gemäß Anspruch 7, wobei ein Druckwellenschutzring (15) zwischen dem zentralen
Pilotbohrmeißelabschnitt (2) und dem Spannfutter (12) angeordnet ist.
9. Bohrwerkzeug gemäß Anspruch 8, wobei der Druckwellenschutzring (15) einen sich verjüngenden
Querschnitt aufweist.
10. Bohrwerkzeug gemäß einem der vorstehenden Ansprüche, wobei der zentrale Pilotbohrmeißelabschnitt
(2) sich axial erstreckende Spülrillen (21) umfasst.
11. Bohrwerkzeuganordnung umfassend eine Vielzahl von zentralen Pilotbohrmeißelabschnitten
(2) gemäß einem der vorstehenden Ansprüche, wobei die Vielzahl von zentralen Pilotbohrmeißelabschnitten
(2) mindestens zwei unterschiedliche Bohrmeißelabschnitte (2) einschließt, die eingerichtet
sind, unterschiedliche Arten von Bohren zu bewältigen.
12. Verfahren zum Zusammenbau eines Bohrwerkzeugs umfassend die Schritte von
a. Bereitstellen einer Bohranordnung (10) mit einem zentralen Pilotbohrmeißelabschnitt
(2), einem am Rand liegenden ringförmigen Bohrmeißelabschnitt (4) und einem Gehäuseschuh
(3),
b. Bereitstellen eines Gehäuserohrs (13) und eines Bohrstrangs,
c. gekennzeichnet durch
d. weiterhin Bereitstellen einer Antriebswellenvorrichtung (9) und
e. Verbinden der Antriebswellenvorrichtung (9), um Drehmoment von einem Bohrstrang
zu übertragen, und
f. lösbar Verbinden der Antriebswellenvorrichtung (9) mittels einer Drehmomentkopplung
(16, 23, 93) mit dem zentralen Bohrmeißelabschnitt (20).
13. Verfahren gemäß Anspruch 12, weiterhin auch lösbar Verbinden der Antriebswellenvorrichtung
(9) mittels einer axialen Kopplung (25, 95, 250) mit dem zentralen Bohrmeißelabschnitt
(20).
14. Verfahren gemäß Anspruch 13, weiterhin Bereitstellen einer Vielzahl von zentralen
Pilotbohrmeißelabschnitten (2), einschließlich mindestens zweier unterschiedlicher
Bohrmeißelabschnitte (2), und Austauschen eines zentralen Bohrmeißelabschnitts (2)
mit einem Bohrmeißelabschnitt (2) eines unterschiedlichen Typs, um unterschiedliche
Arten von Bohren zu bewältigen.
15. Verfahren gemäß Anspruch 14, wobei der Austausch sich darauf bezieht, unterschiedliche
Arten von Löchern zu bewältigen.
16. Verfahren gemäß Anspruch 14, wobei der Austausch sich darauf bezieht, unterschiedliche
Arten von Böden zu bewältigen.
1. Outil de forage pour le forage en fond de trou, lequel outil de forage est agencé
pour percer un trou à l'avant d'un tube d'enveloppe (13) qui suit, l'outil de forage
comprenant un ensemble de forage (10) comprenant un trépan pilote central (2, 9),
un sabot d'enveloppe (3) et une partie formant trépan (3, 4) en forme d'anneau périphérique
externe fixé de façon libérable audit trépan pilote central (2, 9), ledit ensemble
(10) étant relié à un train de tiges de forage, caractérisé en ce que le trépan pilote central (2) comprend une partie de trépan pilote central (2) et
un dispositif (9) formant arbre d'entraînement qui sont agencés pour s'inter-emboîter
de façon libérable afin de transmettre à l'ensemble de forage (10) du couple provenant
du train de tiges de forage, le dispositif (9) formant arbre d'entraînement présentant
une partie inférieure (92) en forme d'arbre, qui s'emboîte de façon amovible dans
un trou central (22) de la partie formant trépan pilote (2) au moyen d'un premier
agencement de liaison (16, 96, 23, 93), ladite partie (92) en forme d'arbre étant
agencée avec des organes de liaison (16, 96) comprenant chacun un rayon extérieur
agencé pour venir correspondance avec des évidements intérieurs (23) aménagés dans
le trou central (22), chaque évidement (23) comprenant un rayon intérieur correspondant
au rayon extérieur desdits organes de liaison (16, 96), de sorte qu'une liaison de
transmission de couple est obtenue.
2. Outil de forage selon la revendication 1, dans lequel ledit premier agencement de
liaison (16, 23, 93) est agencé au moyen de pièces de liaison (16) amovibles agencées
pour correspondre à des évidements (93) aménagés autour de la périphérie de ladite
deuxième extrémité (92), et également pour correspondre à des évidements intérieurs
(23) aménagés dans ledit trou central (22), de sorte que lors de la liaison, le mouvement
de rotation de l'arbre d'entraînement (9) est transmis audit ensemble (10).
3. Outil de forage selon l'une quelconque des revendications précédentes, dans lequel
le dispositif (9) formant arbre d'entraînement est relié axialement au trépan pilote
central (2) au moyen d'un deuxième agencement de liaison axial (25, 95, 250) libérable.
4. Outil de forage selon la revendication 3, dans lequel ledit deuxième agencement de
liaison (25, 95, 250) libérable comprend au moins une bille de verrouillage (250),
de préférence un certain nombre de billes de verrouillage (250), disposées dans un
évidement circonférentiel (25) aménagé à l'intérieur dudit trou central (22) du trépan
pilote central (2) et également dans un évidement circonférentiel (95) aménagé autour
de la périphérie du dispositif (9) formant arbre d'entraînement.
5. Outil de forage selon la revendication 4, dans lequel un alésage radial (251) est
aménagé dans le corps dudit trépan pilote central (2), étant agencé pour faciliter
la mise en place et le retrait desdites billes de verrouillage (250).
6. Outil de forage selon la revendication 5, dans lequel la partie (2) formant trépan
pilote central comprend une première bride (27) et une deuxième bride (28), ladite
première bride (27) étant agencée pour transmettre de l'énergie de percussion à ladite
partie formant trépan (2) indirectement via ledit sabot d'enveloppe (3), et ladite
deuxième bride (28) étant agencée pour transmettre de l'énergie de percussion directement
audit anneau de trépan (4).
7. Outil de forage selon l'une quelconque des revendications précédentes, dans lequel
l'outil de forage (1) comprend un mandrin (12) agencé pour transmettre audit ensemble
de forage (10) le couple généré par ledit train de tiges de forage.
8. Outil de forage selon la revendication 7, dans lequel il y a un anneau de protection
anti-explosion (15) positionné entre la partie de trépan pilote central (2) et le
mandrin (12).
9. Outil de forage selon la revendication 8, dans lequel l'anneau de protection contre
les explosions (15) a une section transversale allant en s'effilant.
10. Outil de forage selon l'une quelconque des revendications précédentes, dans lequel
la partie (2) formant trépan pilote central comprend des rainures (21) d'écoulement
de flux s'étendant axialement.
11. Ensemble formant outil de forage comprenant une pluralité de parties de trépan pilote
central (2) selon l'une quelconque des revendications précédentes, dans lequel ladite
pluralité de parties de trépan pilote central (2) comprend au moins deux parties de
trépan (2) différentes agencées pour mettre en oeuvre différents types de forage.
12. Procédé d'assemblage d'un outil de forage comprenant les étapes consistant à
a. utiliser un ensemble de forage (10) ayant une partie (2) formant trépan pilote
central, une partie (4) formant trépan en forme d'anneau périphérique et un sabot
d'enveloppe (3),
b. utiliser un tube d'enveloppe (13) et un train de tiges de forage,
c. caractérisé par le fait
d. d'utiliser en outre un dispositif (9) formant arbre d'entraînement et
e. de connecter le dispositif (9) formant arbre d'entraînement pour transférer du
couple provenant d'un train de tiges de forage, et
f. de relier à la partie (20) formant trépan central, de manière libérable, le dispositif
(9) formant arbre d'entraînement au moyen d'un agencement de liaison de couple (16,
23, 93).
13. Procédé selon la revendication 12, reliant en outre également à la partie (20) formant
trépan central, de manière libérable, le dispositif (9) formant arbre d'entraînement
au moyen d'un agencement de liaison axial (25, 95, 250).
14. Procédé selon la revendication 13, comprenant en outre le fait de prévoir une pluralité
de parties (2) de trépan pilote central comprenant au moins deux parties de trépan
(2) différentes et le fait d'échanger une partie (2) formant trépan central pour un
type différent de partie de trépan (2) afin de mettre en oeuvre différents types de
forage.
15. Procédé selon la revendication 14, dans lequel ledit fait d'échanger est lié à la
réalisation de différents types de trous.
16. Procédé selon la revendication 14, dans lequel ledit fait d'échanger est lié à la
prise en compte de différents types de sols.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only.
It does not form part of the European patent document. Even though great care has
been taken in compiling the references, errors or omissions cannot be excluded and
the EPO disclaims all liability in this regard.
Patent documents cited in the description