Note: Descriptions are shown in the official language in which they were submitted.
CA 02864379 2014-09-22
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Release assembly and method of forming drilling tool
Background of the invention
The invention relates to a release assembly of a drilling tool used in
rock drilling and overburden drilling. The release assembly is intended to be
arranged axially between two drilling tool components, which can be connect-
ed together at a joint by means of connecting threads.
The invention further relates to a use of the release assembly and a
method of forming a drilling tool for rock drilling or overburden drilling.
The field of the invention is defined more specifically in the pream-
bles of the independent claims.
In mines and at other work sites, drilling machines are used for drill-
ing bore holes into rock surfaces and soil. The drilling machine comprises a
rotating device for rotating a drilling tool during drilling. In many drilling
applica-
tions the drilling machine also comprises a percussion device for generating
impact pulses to the tool. The drilling tool may be composed of several
drilling
tool components, which are arranged axially successively and connected to
each other by means of connecting threads. Opening of the connecting
threads between the drilling components after drilling procedures has proven
difficult. The connecting threads have a tendency to get stuck. The stuck
joint
causes loss of time and money.
Brief description of the invention
An object of the invention is to provide a novel and improved ar-
rangement for release of connecting threads between drilling components. A
further object is to provide a novel and improved method of forming a drilling
tool.
The release assembly according to the invention is characterized in
that the connecting threads of the joint have a first handedness; and the
first
counter surface and second counter surface are both provided with at least
one inclined flank surfaces having a second handedness opposite to the first
handedness of the connecting threads, whereby the release assembly is ar-
ranged to be lengthened when the first counter surface and the second coun-
ter surface are turned relative to each other in a closing direction of the
first
handedness, and is arranged to be shortened when turned in an opening di-
rection of the first handedness.
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The method according to the invention is characterized by arranging
between the successive drilling tool components the release assembly, which
is in accordance with claim 1.
An idea of the disclosed solution is that a drilling tool is provided
with at least one release assembly. The release assembly is arranged at a
joint
between two successive axial drilling tool components. The release assembly
has an axial length. The release assembly comprises a release mechanism,
which allows the axial length of the release assembly to shorten when the
joint
is opened.
Furthermore, connecting threads and counter surfaces of the re-
lease assembly are opposite in handedness regarding their opening and clos-
ing directions. The connecting threads of the joint have a first handedness.
The
first counter surface and second counter surface are both provided with at
least one inclined flank surface having a second handedness opposite to the
first handedness of the connecting threads. Thus, the release assembly is ar-
ranged to be lengthened when the first counter surface and the second coun-
ter surface are turned relative to each other in a closing direction of the
first
handedness, and is arranged to be shortened when turned in an opening di-
rection of the first handedness. In other words, when the connecting threads
are right handed, the flank surfaces are left handed, and vice versa.
An advantage of the disclosed solution is that the release assembly
provides easy opening of the connection threads between the successive drill-
ing tool components. When the release mechanism shortens in response to
the turning in the opening direction, friction forces are decreased and
opening
is facilitated. Furthermore, inclined flank surfaces are easy to manufacture
and
they endure forces and wear well.
According to an embodiment, the release assembly comprises at
least one first intermediate component and at least one second intermediate
component. Both of the intermediate components comprise counter surfaces
facing each other, and contact surfaces facing th6 drilling components of the
joint. Thanks to this embodiment, the release assembly is a separate and in-
dependent piece, which may be placed between the connectable drilling com-
ponents without any modifications to a basic design of the drilling tool compo-
nents.
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According to an embodiment, the release assembly comprises one
single intermediate component. Then the intermediate component is provided
with the first counter surface and a contact surface. Further, one of the con-
nectable drilling components of the joint is provided with the second counter
surface. Thus, the second counter surface is an integrated part of the
drilling
tool component. This embodiment may be beneficial when the number of com-
ponents or axial length of the release assembly needs to be minimized, for ex-
ample.
According to an embodiment, the connecting threads and the in-
clined flank surfaces of the counter surfaces are opposite in handedness re-
garding their opening and closing directions. The connecting threads have a
first pitch angle and the inclined flank surfaces have a second pitch angle.
The
second pitch angle is greater than the first pitch angle. Thanks to this
embodi-
ment even rather a small turning motion in the opening direction may decrease
tightening force of the flank surfaces and generate needed axial shortening.
However, the second pitch angle should be less than fivefold relative to the
first pitch angle. This way, unintended opening of the release assembly may be
avoided due to the influence of dynamic forces during the use of the drilling
tool.
According to an embodiment, the second pitch angle of the inclined
flank surfaces is 2 to 3 fold relative to the first pitch angle of the
connecting
threads. This embodiment has shown to be usable when tested in practice.
According to an embodiment, the second pitch angle of the inclined
flank surfaces is smaller than the first pitch angle of the connecting
threads.
Thus, this embodiment is contrary to what has been described in the previous
two paragraphs above. This embodiment may be usable in situations where an
unintentional opening of the release assembly is a problem.
According to an embodiment, the first counter surface is provided
with one or more first transverse surfaces and the second counter surface is
provided with one or more second transverse surfaces. The transverse surfac-
es are transverse relative to the inclined flank surfaces. The transverse
surfac-
es may be in axial direction, perpendicular to the flank surfaces or in a
desired
angular direction. The first transverse surface is facing the second
transverse
surface and one or more flexible member is arranged between them. The flexi-
ble member occupies a distance between the transverse surfaces. The flexible
member prevents the transverse surfaces from being positioned in contact with
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each other. In other words, the flexible member allows the counter elements or
surfaces to be turned in their opening direction relative to each other.
According to an embodiment, the above mentioned flexible member
is made of one or more resilient materials, such as rubber or elastic polymer.
When the release assembly is turned in the opening direction, the resilient ma-
terial may be temporarily compressed or reshaped.
According to an embodiment, the above mentioned flexible member
is a separate element, which is installed between the transverse surfaces fac-
ing each other. The separately manufactured flexible member is easy to place
between the transverse surfaces and it can be changed later if need be. At its
simplest implementation the separate flexible member may be a rubber piece.
According to an embodiment, one or both of the opposing trans-
verse surfaces are covered by a resilient material, which serves as the
flexible
member. Between the transverse surfaces there may be a space filled with the
resilient material. Alternatively, the faces of the transverse surfaces may be
coated with the resilient material. The resilient material may be rubber or
rub-
ber ¨like material. Some polymers, such as polyurethane PU, are also suitable
for the purpose. In this embodiment the flexible member is prearranged or in-
tegrated in the release assembly, thus allowing easy and fast mounting of the
release assembly.
According to an embodiment, the transverse surfaces are held at a
distance from each other by means of one or more spring members. When the
release assembly is turned towards the opening direction, then the spring
member will compress and allow the release assembly to be shortened in the
axial direction. In some situations it may be more convenient to use the
spring
member as a flexible member instead of the above mentioned resilient materi-
al.
According to an embodiment, the contact surface of the intermedi-
ate component is provided with one or more friction zones having an intention-
ally increased friction coefficient. The friction zone may be provided with
inten-
tionally increased surface roughness. The friction zone may comprise a knurl-
ing, for example. Alternatively, the friction zone may be covered with
friction
material having a greater friction coefficient compared to the basic material
of
the intermediate component. The contact surface may have one or several
smaller friction zones, and one or more additional zones without the disclosed
feature, or alternatively, the entire contact surface is treated for obtaining
the
CA 02864379 2014-09-22
increased friction coefficient for the entire area. The idea of the friction
zone is
to prevent unintentional opening of the connecting threads by increasing fric-
tion forces between the intermediate component and the connectable drilling
tool component.
5 According to an embodiment, the contact surface of the intermedi-
ate component has a tapered shape. Thanks to the tapered shape, contact
area between the intermediate piece and the connectable drilling tool compo-
nent may be increased. The intermediate component may comprise the ta-
pered contact surface on an outer periphery, or alternatively on an inner pe-
riphery of the intermediate component.
According to an embodiment, the intermediate component has an
outer periphery and an inner periphery, which both comprise one or more
curved surfaces. The outer periphery and the inner periphery may both have
closed form.
According to an embodiment, the intermediate component has a
ring shaped configuration, whereby it has an outer circumference and an inner
circumference. The intermediate component may have a circular or elliptical
shape, for example.
According to an embodiment, the intermediate component is formed
of two or more separate pieces. The intermediate component may be sleeve
like piece which is formed of two halves, for example.
According to an embodiment, the counter surface of the intermedi-
ate component is formed of two or more separate pieces. The intermediate
piece may be provided with several counter pieces mounted in recesses on the
counter surface.
According to an embodiment, the release assembly is intended to
be used in a down-the-hole drilling (DTH). Then the release assembly is ar-
ranged between a drill bit assembly and a down-the-hole percussion device.
The drill bit assembly comprises a drill bit and fastening members for
fastening
the drill bit. The down-the-hole percussion device is also known as a DTH ¨
hammer.
According to an embodiment, the release assembly is used in the
DTH ¨drilling. The release assembly is arranged between a locking nut of the
drill bit assembly and the DTH -hammer. The locking nut is also known as a
driver sub.
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According to an embodiment, the release assembly is intended to
be used in an extension drilling. Then the release assembly is arranged be-
tween two successive drilling tool components. The drilling tool component
may be a drill bit, a drill rod or a drill pipe, for example.
According to an embodiment, the release assembly is intended to
be used in a rotary drilling. Then the release assembly is located between ro-
tating unit and a drill bit. Between the rotating unit and the drill bit there
may be
one or more drill tubes or rods provided with connecting threads.
According to an embodiment, the release assembly is intended to
be used in a top-hammer drilling. Then the release assembly is located be-
tween a drilling machine and a drill bit, which are located at opposite ends
of
the drilling equipment. Between the drilling machine and the drill bit there
may
be one or more drill tubes or rods provided with connecting threads.
According to an embodiment, the release assembly is without any
connection threads. Instead two drilling tool components are provided with
needed connection threads for connecting them in a joint. Thus, surfaces of
the release assembly that are arranged against the connectable drilling tool
components are not provided with connection threads. The release assembly
may be an intermediate piece arranged between the two connectable drilling
tool components without being fastened to the drilling tool components by
means of connection threads.
The above-disclosed embodiments can be combined to form suita-
ble solutions provided with necessary features disclosed.
Brief description of the figures
Some embodiments are described in more detail in the accompany-
ing drawings, in which
Figure 1 is a side view of a rock drilling rig provided with a drilling
unit,
Figure 2 shows schematically the principle of DTH drilling,
Figure 3 is a schematic and partly sectional side view of a release
assembly arranged between two consecutive drilling tool components,
Figure 4 is a schematic side view of a release assembly when
turned in an opening direction,
Figure 5 is a schematic side view of a release assembly wherein a
spring serves as a flexible member,
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Figure 6 is a schematic side view of a release assembly wherein a
flexible, formable or resilient filling material serves as a flexible member,
Figures 7a ¨ 7c show schematically and in axial direction intermedi-
ate components comprising several sections each provided with inclined flank
surfaces and transverse surfaces in their counter surfaces,
Figures 8a and 8b show schematically contact surfaces of the in-
termediate component provided with one or more friction zones,
Figure 9 is a schematic side view of a release assembly comprising
two intermediate components and being arranged in a shoulder contact in a
joint between two drill rods,
Figure 10 is a schematic side view of a release assembly compris-
ing only one intermediate component and being arranged in a shoulder contact
in a joint between two drill rods,
Figure 11 is a schematic side view of a release assembly arranged
inside a coupling sleeve of a joint between two drill rods and having a bottom
contact,
Figure 12 is a schematic side view of a drill bit assembly of a DTH ¨
drilling device,
Figure 13 is a schematic and partially sectional side view of a joint
between a DTH ¨hammer and a drill bit assembly, wherein a release assembly
has a shoulder contact,
Figure 14 is a schematic and partially sectional side view of an al-
ternative joint between a DTH ¨hammer and a drill bit assembly, wherein a
release assembly has a bottom contact, and
Figure 15 is a schematic and partially sectional side view of an al-
ternative joint between a DTH ¨hammer and a drill bit assembly, wherein a
release assembly has an intermediate component provided with a tapered con-
tact surface facing a drilling tool component.
For the sake of clarity, the figures show some embodiments of the
disclosed solution in a simplified manner. In the figures, like reference
numer-
als identify like elements.
Detailed description of some embodiments
Figure 1 shows a rock drilling rig 1, comprising a rock drilling unit 2
which may be connected by means of a boom 3 to a movable carrier 4. The
drilling unit 2 may comprise a feed beam 5 and a rock drilling machine 6 sup-
ported on it. The rock drilling machine 6 may be moved on the feed beam 5 by
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means of a feed device 7. The rock drilling machine 6 comprises a shank 8 at
a front end of the rock drilling machine 6 for connecting a tool 9. The tool 9
may comprise one or more drill rods 10 and a drill bit 11 located at a distal
end
of the tool 9. The rock drilling machine 6 further comprises a rotating device
12
for rotating the shank 8 and the tool 9 connected to the shank 8. When the
rock drilling is based on rotation R and feed F of the tool then the drilling
is
known as rotary drilling. However, the rock drilling machine 6 may also com-
prise an impact device or percussion device 13 for generating impact pulses to
the tool 9. When the rock drilling machine 6 is provided with the percussion
device 13, which is located on an opposite end of the tool 9 as compared to
the drill bit 11, the drilling is known as top-hammer drilling.
The tool 9, the drill rods 10 of the tool and the drill bit 11 are drilling
tool components 14, which are arranged axially and consecutively. Between
the consecutive drilling tool components 14 are joints 15 for interconnecting
the components. The joint 15 may comprise connecting threads allowing
mounting and dismounting of the joint by screwing the drilling tool components
14 relative to each other around the centre line of the tool 9. Further, the
front
end of the tool 9 may be connected to the shank 8 by means of a joint 15
comprising connecting threads. The connecting threads of the joints 15 may
stuck, wherefore the joints 15 may be provided with a release assembly de-
scribed in this application.
At a drilling site, one or more drill holes 16 are drilled with the drilling
unit 2. The drill holes 16 may be drilled in a vertical direction, as is shown
in
Figure 1, or alternatively, in a horizontal direction or in an angular
direction.
The drill holes 16 may be drilled to a rock material or soil.
Figure 2 shows a drilling unit 2 for DTH ¨drilling. The drilling unit 2
differs from the one in Figure 1 in such a way that the percussion device 41
is
at the opposite end of the tool 9 in relation to the rotating device 12 or
rotation
unit. During drilling, the percussion device 41 is in the drill hole 16, and
the
drill bit 11 may be connected directly to the percussion device 41. The drill
bit
11 or a drill bit assembly may be connected to the percussion device 13 by
means of a locking nut 37, known also as a driver sub. As it is shown in
Figure
2, the tool 9 may comprise one or more drill rods 10 or tubes, which may be
connected consecutively by means on joints 15 provided with connecting
threads. Further, the rear end of the tool 9 may be connected to the shank 8
by
means of a joint 15 also comprising connecting threads. Between the locking
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nut 37 and a front end of the percussion device 41 is also a joint 15 with con-
necting threads. The connecting threads of the joints 15 may stuck, wherefore
the joints 15 may be provided with a release assembly described in this appli-
cation. The tool, the extension drill tubes, the drill bit assembly and the
percus-
sion piston are all drilling tool components 14, which are arranged axially
and
one after the other and are used during drilling. Between the consecutive
drill-
ing tool components 14 are joints 15 for connecting the components to each
other.
Figure 3 discloses a release assembly 18 in a simplified manner. In
this embodiment the release assembly 18 is arranged in a joint 15 between
two consecutive axial drilling tool components 14a and 14b, which are in this
particular example a drill tube 10 and a drill bit 11 provided with a
fastening
part 19. An outer surface of the fastening part 19 is provided with outer con-
necting threads 20 and the drill tube 10 is provided with inner connecting
threads 21. The connecting threads 20, 21 match to each other and they have
a first pitch angle P1. The release assembly 18 may comprise a first intermedi-
ate component 22a and a second intermediate component 22b, which are
separate from the drilling tool components 14a, 14b. The intermediate compo-
nents 22a, 22b have contact surfaces 24 facing the drilling tool components
14. The intermediate components 22a, 22b comprise counter elements facing
towards each other and comprising a release mechanism 25 allowing an initial
axial length L1 to be shortened in response to turning the connecting threads
20, 21 of the joint 15 in an opening direction Ro. The shortened axial length
L2
after execution of the release mechanism 25 is shown in Figure 3, too. A clos-
ing direction Rc is also indicated in the Figure.
In the disclosed embodiment of Figure 3 the counter elements of the
release mechanism 25 are a first counter surface 26 and a second counter
surface 27, which are facing each other. The first counter surface 26 and the
second counter surface 27 are both provided with one or more inclined flank
surfaces. The connecting threads 20, 21 have a first handedness and the in-
clined flank surfaces of the counter surfaces 27, 28 have a second handed-
ness. When the connecting threads are right-handed, the inclined flank surfac-
es are left-handed, and vice versa. The inclined flank surfaces of the counter
surfaces 26, 27 have a second pitch angle P2. The second pitch angle P2 is
greater than the first pitch angle P1 of the connecting threads 20, 21, as is
clearly shown in Figure 3.
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The first counter surface 26 may comprise a first transverse surface
28 and the second counter surface 27 may comprise a second transverse sur-
face 29, which are facing each other. The transverse surfaces 28, 29 define a
space 30 inside which is arranged a flexible member 31. The flexible member
5 31 occupies a distance D1 between the transverse surfaces 28, 29.
VVhen the first counter surface 26 and the second counter surface
27 are turned relative to each other in a closing direction Rc, the axial
length of
the release assembly 18 is lengthened. The release assembly 18 then has the
initial length L1. When the joint 15 opened and the first counter surface 26
is
10 turned relative to the second counter surface 27 in an opening direction
Ro,
the axial length of the release assembly 18 is shortened. The release assem-
bly 18 then has the second axial length L2 and as a consequence of that, fric-
tion forces are decreased in the joint 15 allowing easy opening of the joint
15.
The flexible member 31 allows the relative movement of the intermediate corn-
ponents 22a, 22b towards the opening direction Ro. The flexible member 31
may be a separate piece arranged in the space 30. The flexible member may
be a rubber piece, for example.
Let it further be mentioned that the intermediate components 22a,
22b may be sleeve-like pieces having an outer diameter 32 and an inner diam-
eter 33. However, other shapes and forms are also possible. An additional
embodiment may comprise only one intermediate component 22a or 22b since
one of the drill tool components 14a or 14b may have an integrated counter
surface 26 or 27.
In Figure 4 the release assembly 18 is turned towards the opening
direction Ro whereby the transverse surfaces 28 and 29 are moved towards
each other and the space 31 occupied by the flexible member 30 has a de-
creased distance D2. The flexible member 31 may change its shape or may
compress, depending on the structure and material used. In this embodiment
the flexible member 31 is flattened allowing the relative movement of the in-
termediate components 22a, 22b and shortening Ls of length of the release
assembly 18. The initial position of the first transverse surface 28 is shown
in
dotted lines.
In Figure 5 the flexible member 31 of the release assembly 18 is a
spring arranged in the space 30. The spring may be a spiral spring, for exam-
ple.
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In Figure 6 the flexible member 31 is a flexible material cast, inject-
ed or otherwise arranged in the space 30. The flexible material filling the
space
30 may be polyurethane, for example. The flexible material may combine the
transverse surfaces 28, 29 together, whereby the intermediate components
22a, 22b are connected to form one uniform object. Figure 6 further differs
from the solutions disclosed in Figures 3 ¨ 5 in that the inclined flank
surfaces
of the counter surfaces 26, 27 are opposite in handedness. The handedness of
the inclined flank surfaces may be designed according to the handedness of
the connecting threads. The handedness is shown in Figures of this application
only by way of example. The handedness of the release assembly 18 has no
effect on other features shown in the Figures.
Figure 7a shows that the intermediate component 22 may comprise
several inclined flank surfaces and transverse surfaces 29 in the counter sur-
face 27. In the solution shown in Figure 7a the counter surface 27 is divided
into four sections, but the number of sections may be 2 or 3, or more than 4.
In Figure 7b the intermediate component 22 is formed of two halves
23a and 23b. It is also possible to form the intermediate component of even
more than two pieces. Figure 7b further shows that the transverse surfaces 29
may be coated with a flexible material, whereby the flexible member 31 is inte-
grated to the intermediate component.
Figure 7c further shows that the intermediate component 22 may
have a form different from a basic sleeve. The intermediate component 23 may
have a slot 32, whereby the outer periphery is not closed. On the other hand
the outer surface of the release assembly 18 needs not to be circular but may
have any suitable form.
Figures 8a and 8b show that the contact surface 24 of the interme-
diate component 22 may comprise one or more friction zones 33, which all
have an increased friction coefficient compared to a friction coefficient of
the
basic material of the intermediate component. The friction zone 33 may com-
prise a knurling or other surface treatment, or alternatively, it may comprise
a
coating.
Figure 9 shows a release assembly 18 arranged in a joint 15 be-
tween two drill rods or tubes of an extension drilling tool. The first drill
tool
component 14a may have a shoulder 34 against which the release assembly
18 is arranged.
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Figure 10 shows an alternative embodiment of the solution of Figure
9. The release assembly 18 comprises only one intermediate component 22b
since the first counter surface 26 and the first transverse surface 28 are
inte-
grated to an end face of the first drilling tool component 14a.
Figure 11 shows a joint 15 wherein the second drill tool component
22b comprises a connecting sleeve 35. The release assembly 18 may be lo-
cated at the bottom of the connecting sleeve 35.
Figures 9 ¨ 11 may relate to top-hammer solutions, where the con-
necting threads are typically left-handed wherefore the inclined surfaces of
the
release assembly 18 are right-handed.
Figure 12 discloses a drilling tool assembly 36 comprising a drill bit
11 and a locking nut 37. The drill bit 11 may comprise a fastening part 19
around which a fastening portion 38 of the locking nut 37 may be arranged.
The fastening portion 38 is provided with connecting threads 20. The locking
nut 37 may further comprise a gripping portion 39. At a distal end of the fas-
tening part 19 of the drill bit 11 is an impact surface 40 for receiving
impact
pulses. The fastening part 19 may slide axially relative to the locking nut 37
during the operation of the percussion device 41.
Figure 13 shows that a release assembly 18 may be placed be-
tween a down-the-hole percussion device 41 and a drilling tool assembly 36.
The DTH percussion device 41 comprises a percussion piston 42 arranged to
strike the impact surface 40 of the drilling tool assembly 36. The connecting
threads 20 of the drilling tool assembly 36 are connected to connecting
threads
provided on an inner surface of the percussion device 41. The release assem-
bly 18 allows easy opening of the connecting threads according to the princi-
ples described above in this application.
In Figure 14 the release assembly 18 is located in an alternative po-
sition as compared to the solution of Figure 13. The release assembly 18 is
inside the percussion device 41 between a retaining element 43 and an end
surface 44 of the fastening portion 38 of the locking nut 37. In Figure 14 the
release assembly 18 has a bottom contact with the drilling tool components
14a, 14b of the joint 15, whereas in Figure 13 a shoulder contact is applied.
In Figures 13 and 14 the second intermediate component 22b of the
release assembly 18 may be an integrated part of the locking nut 37. Then an
upper surface of the gripping portion 39 may comprise elements needed for
acting as a part of the release mechanism.
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Figure 15 shows a joint 15, which has almost the same features as
shown in the solution of Figure 13. However, in Figure 15 the second interme-
diate component 22b of the release assembly 18 has a tapered contact sur-
face 24t against the gripping part 39 of the locking nut 37. Alternatively or
in
addition to, the contact surface 24 of the first intermediate component 22a
may
also have a tapered shape. Then, of course, the corresponding surfaces of the
drilling tool components 14a, 14b facing the release assembly need to be ta-
pered too. Furthermore, one could consider applying the disclosed tapered
contact surfaces also at least in solutions of Figures 3, 9 and 10.
Figures 12 ¨ 15 relate to DTH -hammer solutions, where the con-
necting threads are typically right-handed wherefore the inclined surfaces of
the release assembly 18 are left-handed.
The drawings and the related description are only intended to illus-
trate the idea of the invention. In its details, the invention may vary within
the
scope of the claims.
