Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR DRILLING, IN PARTICULAR PERCUSSION OR ROTARY
PERCUSSION DRILLING, HOLES IN SOIL OR ROCK MATERIAL,
AND DEVICE THEREFOR
The present invention relates to a method for drilling, in
particular percussion or rotary percussion drilling, holes in
soil or rock material, wherein a borehole is formed by a drill
bit mounted on a drill rod assembly by a percussive and/or
rotational movement, a casing adjoining the drill bit is
introduced into the borehole by being pulled and/or struck, and
material that is removed is introduced into the annular space
formed between the outer circumference of the drill rod assembly
and the inner circumference of the casing via at least one
passage opening formed between the drill bit and the casing, and
is discharged from the borehole. The invention further relates
to a device for drilling, in particular percussion or rotary
percussion drilling, holes in soil or rock material, wherein a
borehole is formed by a drill bit mounted on a drill rod
assembly by a percussive and/or rotational movement, a casing
adjoining the drill bit is introducible into the borehole by
pulling and/or striking, and removed material is introducible
into the annular space formed between the outer circumference of
the drill rod assembly and the inner circumference of the casing
via at least one passage opening formed between the drill bit
and the casing, and is dischargeable from the borehole.
For the production of holes in soil or rock material by
percussion or rotary percussion drilling, the impact energy, by
the aid of a drill bit mounted on a drill rod assembly, is
applied to the drill bit either directly via the drill rod
assembly or via complex devices like impact shoes, while
additionally introducing into the borehole a jacket tube or
casing to provide an optionally required further lining, or
safely prevent the breaking in of material.
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The selection of the drill ' bit to be employed, of the drill rod
assembly and of the casing, which is either pulled along or
driven in, depends on the soil or rock material to be removed,
and on whether the hole formed in the soil or rock material is
to be subsequently used for receiving a rock bolt, forming a
pipe roof or even draining the soil or rock material, as well as
on the soil or rock material and, in particular, its hardness,
stratification, yet even on whether such soil or rock material
comprises inclusions like mountain water or the like, wherein
the most diverse elements such as drill bits, drill rod
assemblies and, in particular, different casings will frequently
have to be employed on one and the same construction site.
The present invention aims to further develop a method and a
device of the initially defined kind to the effect that an
adaptation to the most different subsoil conditions will rapidly
and reliably become possible, and that any combination of the
elements employed will be freely selectable and usable directly
at place as a function of the respective requirements when
drilling holes in soil or rock material. It is a further object
of the invention to keep the number of different prefabricated
devices for drilling holes as low as possible.
To solve these objects, a method of the initially defined kind
is essentially characterized in that the impact energy of the
drill rod assembly is applied to the drill bit via an adapter
cooperating with the drill bit and the drill rod assembly, and
that the impact energy is applied to the drill bit at least
partially via an impact shoulder of the adapter and at least
partially via a threaded connection between the adapter and the
drill bit. In that the impact energy of the drill rod assembly
is applied to the drill bit via an adapter cooperating with the
drill bit and the drill rod assembly, it has become possible in
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a simple manner to conduct the method according to the invention
in such a manner a to enable the respectively most suitable
elements to be used as a function of the existing mining or
subsoil conditions. In that the method according to the
invention is further conducted such that the impact energy is
applied to the drill bit at least partially via an. impact
shoulder of the adapter and at least partially via a threaded
connection between the adapter and the drill bit, it is, on the
one hand, possible to ensure the safe and reliable transmission
of the impact energy onto the drill bit, and it will, on the
other hand, be safeguarded that the threaded connection provided
for connecting the drill bit with the adapter will not be
knocked out during the drilling operation, and hence eventually
render impossible the loosening of the connection between the
drill bit and the adapter after having completed the drilling
operation.
In order to ensure that, in particular after the completion of
the drilling operation, the adapter can be separated from the
drill bit without damaging any of the components, the method
according to the invention is preferably conducted in such a
manner that the adapter is coupled to the drill bit by screwing
via a quick-acting screw thread connection. In that the adapter
is coupled to the drill bit by screwing via a quick-acting screw
thread connection, it will, in particular, be ensured that the
threaded connection will be safely and reliably undone, and the
drill rod assembly together with the adapter will be removed
from the borehole, after having completed the drilling operation
and, in particular, after having subjected the threaded
connection of the adapter with the drill bit to the high stress
caused by the introduction of the impact energy. It will,
furthermore, be ensured that the adapter will be reusable
several times, which will involve considerable economic
advantages.
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Such a configuration, if f'equifed, will additionally enable,
during the drilling of holes in soil or rock material, the
complete exchange of a drill rod assembly, for instance due to
excessive load or wear or defects on the drill rod assembly, or
if the subsoil conditions, for instance, call for the use of
more stable rods.
In order to ensure that an unintentional detachment of the-drill
rod assembly from the adapter is prevented during the drilling
of holes in rock or soil material, the method according to the
invention is preferably further developed to the effect that the
adapter is coupled to the drill rod assembly by screwing via a
thread, in particular a thread having a smaller pitch than the
threaded connection between the drill bit and the adapter. Such
a configuration of the method according to the invention ensures
that, in particular during drilling, the drill rod assembly plus
adapter can be removed from the borehole without inadvertent
detachment of the connection between the drill rod assembly and
the adapter, so as to be able to perform possibly required
adaptation operations.
In order to ensure that drilling debris formed during the
drilling of holes will be removed without clogging any openings
of the drill bit, the method according to the invention is
preferably further developed to the effect that flushing fluid
is discharged during drilling through the tubular adapter and
through cooperating openings provided in the drill bit. In that
the method according to the invention is conducted such that,
during drilling, flushing fluid is discharged through the
tubular adapter and through cooperating openings provided in the
drill bit, it is feasible to supply sufficient flushing fluid
volume during drilling by the aid of a structurally simple
device both to the working face and optionally also directly to
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an end region of a drill bit, which end region faces away from
the interior of the borehole, or into an annular space provided
between the drill bit and a casing, in order to prevent the
obstruction of openings and passages by drill debris and also to
ensure that an excessive loss of flushing fluid will be avoided
during drilling.
In order to, in particular, prevent the discharge of an
excessive amount of flushing fluid during the drilling
operation, the invention is further developed to the effect that
flushing fluid is intermittently discharged during an engagement
of the drill bit with the soil or rock material via a flush
valve disposed in the adapter and controlled as a function of
said engagement. By the intermittent activation of an
engagement-controlled flush valve during the engagement of the
drill bit with the soil and rock material, an excessive
discharge of fluid, or an excessive amount of fluid introduced
into the borehole through the flush opening of the drill bit,
will, on the one hand, be safely avoided while, on the other
hand, simultaneously ensuring that sufficient fluid volume will
be available in the interior of the borehole for removing the
drill debris.
In order to safely and reliable carry along and, in particular,
pull along a casing into the interior of the borehole
simultaneously with the formation of a hole in soil and rock
material, the method according to the invention is preferably
further developed to the effect that the impact energy, in
addition, is at least partially applied to the casing via an
impact shoulder formed on the drill bit. In that, during the
method for drilling holes in soil and rock material, a portion
of the impact energy is additionally applied to the casing via
an impact shoulder formed on the drill bit, the safe and
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reliable entrainment of the casing into the interior of the
borehole will be safeguarded.
To solve the initially mentioned objects, a device for drilling,
in particular percussion or rotary percussion drilling, soil or
rock material of the initially defined kind is essentially
characterized in that an adapter cooperating with the drill rod
assembly and the drill bit is provided, and that the adapter
cooperates with the drill bit via an impact shoulder of the
adapter and via a threaded connection provided between the
adapter and the drill bit. In that a universally applicable
adapter cooperating with the drill rod assembly and the drill
bit is provided, it has become possible to both freely select
the drill bit and the drill rod assembly in adaptation to the
requirements encountered during the formation of a hole in soil
and rock material and to combine respectively appropriate
elements with one another. In that the adapter is configured
such that the adapter cooperates with the drill bit via an
impact shoulder of the adapter and via a threaded connection
between the adapter and the drill bit, it will be ensured that,
on the one hand, the drilling energy will be safely and reliably
transmitted to the drill bit and, on the other hand, the
threaded connection between the adapter and the drill bit, which
is susceptible to knocking out or damage, will be stressed as
little as possible.
In that, as in correspondence with a preferred further
development of the device according to the present invention,
the adapter is coupled to the drill bit via a quick-acting screw
thread connection, a force distribution will be achieved in such
a manner as to safely prevent damage to the threaded connection,
on the one hand, and to ensure that, during the separation of
the adapter and the drill rod assembly from the drill bit, the
connection between the drill bit and the adapter will be readily
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and reliable undone, in particular prior to the detachment of
other optionally provided threads, on the other hand.
Such a threaded connection can, for instance, be configured as a
quick-acting screw thread connection having two turns, by which
both a safe and reliable retention of the adapter within the
drill bit will be ensured and an intended detachment of the
adapter from the drill bit will be achieved.
In that, as in correspondence with a preferred further
development of the present invention, the device is configured
such that the adapter is coupled to the drill rod assembly via a
further thread having a pitch differing from that of the thread
connection between the adapter and the drill bit and, in
particular, a smaller pitch, it has become possible to safely
prevent any inadvertent detachment of the adapter from the drill
rod assembly both during the drilling operation and while
screwing the adapter out of the drill bit. Such a configuration,
moreover, ensures that at least the drill rod assembly and the
adapter will be recoverable without damage at the end of the
drilling procedure, thus achieving considerable cost savings.
In that, as in correspondence with a preferred further
development of the present invention, the device is configured
such that the end face of the adapter facing the interior of the
borehole is designed to be at least partially chamfered, it has
become possible to safely insert the adapter, which is coupled
to the drill rod assembly, together with the drill rod assembly
into the drill bit and connect the same by screwing, in
particular where maintenance operations are required during the
formation of the borehole, so as to enable adaptation work to be
performed on the drill rod assembly even in case of, for
instance, half-finished holes.
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For the reliable introduction of flushing fluid into the
interior of the borehole, ' the 'invention is preferably further
developed to the effect that the tubular adapter is formed with
a passage opening for flushing fluid facing the interior of the
borehole, and that the passage opening cooperates with openings
for discharging flushing fluid, that are provided in the drill
bit. By such a device, it will be ensured that flushing fluid
will be introduced into the flush openings formed in the drill
bit through the hollowly designed adapter and will be available
in the interior of the borehole for the drilling operation and,
optionally, in the annular space between the drill bit and the
casing such that, on the one hand, the removal of drill debris
will be effected through openings or recesses formed in the
drill bit in a known manner and, on the other hand, clogging of
the openings for both the flushing fluid and the evacuation of
drill debris in the drill bit and/or, optionally, in the annular
space or annular gap will be prevented.
According to a further development of the invention, the device
is configured such that an engagement-controlled flush valve is
provided in the adapter. By providing an engagement-controlled
flush valve in the adapter, the controlled discharge of flushing
fluid through the adapter and through the flush openings formed
in the drill bit has become possible such that, on the one hand,
only those amounts of flushing fluid which are required for the
proper removal of drill debris will be discharged and, on the
one hand, an obstruction of the openings, in particular the
flush opening, by drill debris will be prevented. The
engagement-controlled flush valve can be formed via a pressure
switch or pressure valve provided in the said annular space.
In order to be able to utilize the drilling energy introduced
through the adapter, in particular, also for pulling along a
casing, and to safely and reliably apply the impact energy also
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to a casing, the device according to the invention is further
developed to the effect that the drill bit comprises at least
one impact shoulder for cooperating with the casing and, in
particular, applying an impact stress on the casing. Such a
configuration will ensure that the casing will be subjected to
an impact stress also in its front end region during the
application of an impact stress on the drill bit so as to be
able to be introduced into the borehole without being driven in
from outside. The casing will thus be pulled into the interior
of the borehole by the impact stress exerted on its front end
region.
In that, as in correspondence with a preferred further
development of the present invention, the casing is configured
such that it is designed to be thickened in its end region
facing the interior of the borehole and the thickened portion,
in its end region facing away from the interior of the borehole,
is designed complementary to an impact shoulder of the drill
bit, the cooperation of the complementarily designed impact
shoulder of the drill bit with the thickened region of the
casing will ensure the reliable striking-in or introduction of
the casing into the borehole.
Due to such a configuration, any casing that appears suitable
for the drilling procedure to be expected, e.g. an expandable
casing, can, for instance, be disposed in a drill bit end region
facing away from the interior of the borehole prior to the start
of a drilling procedure, and subsequently fixed to the drill bit
by pressing, in particular in such a manner that the casing will
be non-detachably connected with the drill bit so as to be
longitudinally displaceable along the drill bit. Since, the
thickened portion of the casing, in its end region facing away
from the interior of the borehole, comes into abutment on the
impact shoulder of the drill bit as the drill bit is being
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struck into the borehole, in particular during the application
of impact stress, the reliable 'entrainment of the casing into
the borehole will be ensured. In the event that, during' the
drilling operation, a displacement of the casing is no longer
possible, in particular in the region where the casing is
disposed to be longitudinally displaceable along the drill bit,
the free movement of the casing within the borehole can, for
instance, be restored by exerting an impact stress from outside.
In that, as in correspondence with a preferred further
development of the present invention, the device is further
devised such that the end region of the casing facing the
interior of the borehole is designed with a depression, in
particular an asymmetrically shaped depression, the drill bit
can be thrown off the casing, thus enabling the separation of
the drill bit from the casing and, for instance in the event of
a dividedly designed drill bit, the recovery from the borehole
of at least part of the drill bit together with the drill rod
assembly and the adapter, after having completed the drilling
process.
In the following, the invention will be explained in more detail
by way of exemplary embodiments illustrated in the drawing.
Therein:
Fig. 1 depicts a section through the device according to the
invention for carrying out the method of the invention for
drilling holes;
Fig. 2 is a partially perspective external view of the device
according to Fig. 1;
Fig. 3 is a longitudinal section through a variant of the
adapter of Fig. 1;
Fig. 4 depicts a longitudinal section through a modified variant
of the adapter according to the invention; and
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Fig. 5 depicts a section through the end region facing the
interior of the borehole, of a 'variant of the casing of the
device according to the invention for drilling holes.
From Fig. 1, it is apparent that a device for drilling or rotary
percussion drilling holes in soil or rock material, which is
generally denoted by 1, comprises a drill bit schematically
indicated by 2, which, via an adapter 3, is connected to a drill
rod assembly 4 schematically indicated in Fig. 1.
Furthermore, the drill bit 2 is adjoined by a casing 5 whose end
region 6 facing the interior of the borehole has a thickness
that is enlarged relative to the region of the casing 5 facing
the exterior of the borehole. Said end region 6, in its end
region 7 facing away from the interior of the borehole, is
chamfered and has a shape complementary to an impact shoulder 8
of the drill bit 2. This configuration causes at least a portion
of the impact energy to be applied to the chamfer 7 via the
impact shoulder 8 during the drilling of holes such that the
casing 5 will be entrained into the borehole 1 as drilling
proceeds.
The drill bit 2 is connected to the adapter 3 by a thread
schematically indicated by 9, wherein an annular space 10 is
formed above the end of the adapter 3 facing the borehole and
the drill bit 2, via which annular space 10 flushing fluid can
be discharged towards the interior of the borehole through a
flushing fluid channel 11 provided in the interior of the
hollowly designed adapter 3 and through holes 12 provided in the
drill bit 2 for the passage of flushing fluid.
The drilling energy applied to the adapter 3 via the drill rod
assembly 4 in the configuration according to Fig. 1 is applied
to the drill bit 2 via an impact shoulder 13, on the one hand,
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and partially via the thread 9, on the other hand. Such a
configuration ensures that' the thread 9 will not be excessively
stressed during the drilling operation and, in particular, will
not be knocked out so as to enable the safe and reliable
separation of the adapter 3 from the drill bit 2 after the
drilling operation has been completed.
The drill bit 2 illustrated in Fig. 1 is a conventional drill
bit designed in one piece, which includes a plurality of drill
pins 14 and also recesses 15 beside the openings for discharging
flushing fluid 12, via which recesses drill debris can be
introduced into the annular space 17 provided between the
adapter 3 or the drill rod assembly 4 and the casing 5 through
recesses 16 formed between the casing 5 and the drill bit 2, and
can subsequently be discharged from the borehole exterior. In
order to prevent the annular space 17 from being clogged by
drill debris, the drill bit 2, moreover, comprises a backwardly
directed flushing channel 27 via which the annular space 17 can
be sufficiently rinsed.
In the illustration according to Fig. 2, the reference numerals
of Fig. 1 have been retained, wherein it is apparent from the
illustration according to Fig. 2 that the casing 5, in its end
region 6 facing the interior of the borehole has a diameter that
is reduced relative to that of the region facing the borehole
exterior, which diameter reduction can be readily achieved by
pressing the casing 5 onto a drill bit 2, so that, prior to the
start of a drilling operation, any combination comprising a
drill bit 2, an adapter 3, a drill rod assembly 4 and a casing 5
can be composed as a function of the requirements to be
expected, thus providing an extremely simple and cost-effective
variant of a device for drilling holes in soil and rock
material. Needless to say that the casing 5 in this variant may
be any desired casing as is employed during the drilling of
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holes in soil and rock material, such as a frictionally engaged
casing, an expandable casing, 'a drain pipe or, for instance,
even a casing allowing for a certain mobility of the individual
segments forming the casing and capable of following deviations
from the drilling direction to a certain extent.
Also the drill bit 2 used in this context can be arbitrarily
selected in deviation of the illustrations according to Figs. 1
and 2, wherein, in addition to a drill bit designed in one
piece, a drill bit comprised of several parts, of which, for
instance, only one part will remain in the interior of the
borehole after the completion of the drilling process, an
asymmetrically designed drill bit, and a drill bit comprising
cutters instead of drill pins can be used.
Fig. 2, furthermore, schematically depicts an asymmetrically
designed depression 19 provided on the upper edge 18 of. the
casing 5 that faces the interior of the borehole, which
depression 19 comprises a vertical or steeply formed side cheek
26 and a less sloped second cheek 20, such a depression, for
instance, enabling the drill bit 2 to be thrown off after, the
completion of the drilling operation.
Fig. 3 illustrates a variant of the adapter 3 of Fig. 1, said
adapter again having a thread 9 on its end region to be coupled
to the drill bit 2. The thread 9 of the adapter 3 is configured
as a quick-acting screw thread having two turns, in order to
ensure a safe and reliable connection of the adapter 3 with the
drill bit 2 during the drilling operation, and to enable the
separation of the adapter 3 from the drill bit 2 after the
completion of the drilling operation in such a manner that the
connection between the drill bit 2 and the adapter will be that
connection of the whole device 1 for drilling holes in soil or
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rock material which will come loose first when stressed
accordingly.
Beside the passage channel 11 for flushing fluid, which is again
schematically indicated, a further thread 21 is provided in the
interior of the hollowly designed adapter 3, in its region
facing the exterior of the borehole, for connection to a drill
rod assembly 4, said thread 21 having, on the one hand,
significantly more turns and, on the other hand, a significantly
smaller pitch than the thread 9 in order to safely prevent any
inadvertent loosening of the connection of the adapter 3 with
the drill rod assembly, in particular after the completion of a
drilling operation.
In the variant of Fig. 3, the impact shoulder 13 of the adapter
3, unlike in the illustration according to Fig. 1, is chamfered
in order enable an even better application of the impact energy
to the drill bit 2, wherein the wear of the impact shoulder 13
will, in particular, be clearly reduced with a chamfered impact
shoulder 13.
In the variant according to Fig. 3, the end region 22 of the
adapter 3 facing the interior of the borehole is, moreover,
provided with chamfers 23 to facilitate the insertion or
threading of the adapter 3 into a drill bit 2, which will be of
particular advantage when replacing the drill rod assembly
during a drilling operation.
In the illustration of Fig. 4, which is substantially identical
to that of Fig. 3, the adapter 3 also comprises a quick-acting
screw thread 9 for the insertion of the adapter 3 into a drill
bit 2, as well as a further thread 21, which has a significantly
reduced pitch and a significantly increased number of turns
relative to thread 9. The impact shoulder 13, as in the
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illustration of Fig. 3, is, moreover, chamfered, with a chamfer
23 being formed on the end face 22 of the adapter 3 facing the
interior of the borehole.
Unlike in the illustration according to Fig. 3, the variant
according to Fig. 4 comprises a pressure switch 24 provided on
the end face 22, via which pressure switch 24 an intermittently
openable valve 25 is provided, which is schematically indicated
in the passage 11 for discharging flushing fluid. During the
drilling operation, the pressure switch 24 is actuated by
pressurization at said drilling operation, whereupon the valve
is opened and flushing fluid is either discharged directly
through openings for flushing fluid 12 provided in the drill
bit, or is discharged towards the interior of the borehole via
the annular space 10 provided between the drill bit 2 and the
adapter 3 and through the opening for flushing fluid 12. Such a
configuration safeguards that an excessive consumption of
flushing fluid will be avoided during the drilling operation
while, at the same time, ensuring that the usually extremely
small openings for flushing fluid formed in the drill bit will
not be clogged by drill debris during the drilling operation.
With reference to the adapter 3, it is noted that its external
dimensions such as, e.g. its threads 9 and 21, are designed to
suit all current drill bits 2 and drill rod assemblies 4 such
that the adapter 3 constitutes a universally usable element
whose use does, moreover, not require any conventionally
employed auxiliary equipment such as impact shoes, special
connection sleeves for connecting the drill bit to the drill rod
assembly, and the like, the use of the adapter 3 according to
the present invention thus providing a simplified and
economically favorable and universally usable device for
drilling holes in soil or rock material.
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In the illustration according to Fig. 5, a section, in
particular a longitudinal section, through the end region of a
casing 5 facing the interior of the borehole is shown, said end
region 6 of the casing 5 facing the interior of the borehole
being again thickened. At the transition from the thickened end
region 6 to the portion of the casing 5 facing the exterior of
the borehole, a shoulder 7 is again provided to cooperate with a
shoulder 8 of a drill bit 2 so as to enable the casing 5 to be
pulled into the interior of the borehole.
In the illustration according to Fig. 5, the depression 19 is
shown in the edge region 18 of the casing 5 facing the interior
of the borehole, wherein the side cheek 20 of the depression 19
is designed to extend to the edge 18 with a small gradient. The
second side cheek 26 of the depression 19 is designed to extend
normally to the edge 18, which variant makes it possible to
throw off a drill bit 2 by a slight turn of the casing 5 upon
completion of the drilling procedure in order to either recover
the drill bit 2 at least partially or continue the drilling
procedure without carrying along a casing 5.
In that the casing 5 is pressed on the drill bit 2 in a manner
mounted to be displaceable in the longitudinal direction of the
drill bit 2, as can be taken from the illustration according to
Fig. 1, an impact energy can be additionally applied to the
casing 5 from the exterior of the borehole, if required, in
order to make possible also the driving-in of the casing 5 in
addition to the pulling-in of the casing 5 via the coupling
provided between the impact shoulder 8, the drill bit 2 and the
shoulder 7 of the casing 5. Such driving-in of the casing 5 may
be necessary in some cases such as, e.g. when the passage gap 16
between the drill bit 2 and the casing is clogged by drill
debris, or when further pulling along of the casing 5 by the
drill bit 2 [is not possible]si0 due to broken-in material
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filling the space between the edge 18 of the casing 5 and a
respective portion of the drill bit 2 surmounting the casing 5
or terminating flush with the same.
