U.S. patent application number 13/514211 was filed with the patent office on 2012-10-04 for method for the drilling, in particular percussion or rotary percussion drilling, of holes in soil or rock material and device therefor.
Invention is credited to Karl Bohm, Walter Karpellus.
Application Number | 20120247835 13/514211 |
Document ID | / |
Family ID | 43502667 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120247835 |
Kind Code |
A1 |
Bohm; Karl ; et al. |
October 4, 2012 |
METHOD FOR THE DRILLING, IN PARTICULAR PERCUSSION OR ROTARY
PERCUSSION DRILLING, OF HOLES IN SOIL OR ROCK MATERIAL AND DEVICE
THEREFOR
Abstract
In a method for drilling holes in soil or rock material, wherein
a borehole is formed by a drill bit by a percussive and/or
rotational movement, a casing adjoining the drill bit is introduced
into the borehole and material that is removed is introduced into
the annular space formed between the outer circumference of the
drill rod 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 impact energy of the drill
rod is applied to the drill bit via an adapter cooperating with the
drill bit and a drill rod, and that the impact energy is applied to
the drill bit partially via an impact shoulder of the adapter and
partially via a threaded connection between the adapter and the
drill bit.
Inventors: |
Bohm; Karl; (Holzhausen,
AT) ; Karpellus; Walter; (Innsbruck, AT) |
Family ID: |
43502667 |
Appl. No.: |
13/514211 |
Filed: |
November 5, 2010 |
PCT Filed: |
November 5, 2010 |
PCT NO: |
PCT/AT2010/000422 |
371 Date: |
June 6, 2012 |
Current U.S.
Class: |
175/57 ;
175/293 |
Current CPC
Class: |
E21B 7/20 20130101; E21B
17/0426 20130101; E21D 21/0033 20130101; E21B 10/36 20130101 |
Class at
Publication: |
175/57 ;
175/293 |
International
Class: |
E21B 4/06 20060101
E21B004/06; E21B 7/00 20060101 E21B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2009 |
AT |
A1763/2009 |
Claims
1. 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, wherein 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.
2. The method according to claim 1, wherein that the adapter is
coupled to the drill bit by screwing via a quick-acting screw
thread connection.
3. The method according to claim 1, wherein 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.
4. The method according to claim 1, wherein that flushing fluid is
discharged during drilling through the tubular adapter and through
cooperating openings provided in the drill bit.
5. The method according to claim 4, wherein 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.
6. The method according to claim 1, wherein that the impact energy,
in addition, is at least partially applied to the casing via an
impact shoulder formed on the drill bit.
7. 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 an 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, wherein 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.
8. The device according to claim 7, wherein that the adapter is
coupled to the drill bit via a quick-acting screw thread
connection.
9. The device according to claim 7, wherein 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, in particular a smaller pitch.
10. The device according to claim 7, wherein the end face of the
adapter facing the interior of the borehole is designed to be at
least partially chamfered.
11. The device according to claim 7, wherein 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.
12. The device according to claim 7, wherein an
engagement-controlled flush valve is provided in the adapter.
13. The device according to claim 7, wherein the drill bit
comprises at least one impact shoulder for cooperating with the
casing and, in particular, applying an impact stress on the
casing.
14. The device according to claim 7, wherein the casing is
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.
15. The device according to claim 7, wherein the end region of the
casing facing the interior of the borehole is designed with a
depression, in particular an asymmetrically shaped depression.
Description
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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 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.
[0006] 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.
[0007] Such a configuration, if required, 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.
[0008] 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.
[0009] 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 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.
[0010] 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.
[0011] 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 reliable entrainment of the
casing into the interior of the borehole will be safeguarded.
[0012] 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.
[0013] 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 and reliable undone,
in particular prior to the detachment of other optionally provided
threads, on the other hand.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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 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.
[0020] 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.
[0021] 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 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.
[0022] 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.
[0023] In the following, the invention will be explained in more
detail by way of exemplary embodiments illustrated in the drawing.
Therein:
[0024] FIG. 1 depicts a section through the device according to the
invention for carrying out the method of the invention for drilling
holes;
[0025] FIG. 2 is a partially perspective external view of the
device according to FIG. 1;
[0026] FIG. 3 is a longitudinal section through a variant of the
adapter of FIG. 1;
[0027] FIG. 4 depicts a longitudinal section through a modified
variant of the adapter according to the invention; and
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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, 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.
[0033] 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.
[0034] 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 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.
[0035] 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.
[0036] 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 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.
[0037] 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 rock
material which will come loose first when stressed accordingly.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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
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.
[0042] 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 25 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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].sub.sic
due to broken-in material 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.
* * * * *