Note: Descriptions are shown in the official language in which they were submitted.
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JOINT AND JOINT PARTS FOR DRILL STRING COMPONENTS AND
COMPONENTS
FIELD OF THE INVENTION'
The invention relates to a joint- for a drill rod. The
invention also relates to parts of such a joint and a drill
rod and other drill string- components including such parts.
BACKGROUND OP THE INVENTION
Drill strings for percussion drilling are typically
composed of a number of drill string components, such as drill
rods, that are connected to each other via a threaded joint.
The function of the drill rods is to transmit rotation, feed
force and percussive impacts from the percussive rock drilling
machine to the drill bit. Flushing medium is also. transmitted
through the drill rods.
When the bore hole is completed or in case the drill bit
has to be replaced prematurely, the drill string has to be
retrieved by pulling it out of the bore hole and be
successively disassembled.
Today's conventional drill rods are simple to use and
associated With low- tooling costs. There are, however,
drawbacks associated with the use of today's drill rods such.
.as hole deviation and zig-zasp-shaped hole walls. The
requirement for skilled and experienced operators in order to
obtain acceptable quality results is also a problem.
The threaded joints limit the working life of the rods
since the threads are frequently subjected to wear and
different kinds of failures such as breakages. Furthermore, in
order to ensure secure drilling, the threaded joints, have to
be continuously tightened so, as to ensure proper shock. wave
transmission all the. way through the. drill string.
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In order to loosen threads. prior, to disassembly, the
drill Rt-rilng has to be frequently rattled_
When it. comes to operator skills, an experienced driller
is required in order to most optimally tune feed forte And
rotation and be: careful and. observantduring start of drilling
and to adapt drilling parameters to rock. properties,
'encountered rock formations, start angles vis-a-vis drilling
direction. etc.
The thread joints are subject to wear and are exposed to
risk of failure for many reasons. Meeting threads are subject
to relatively sliding or rubbing wear longitudinally due to
percussion waves and reflections as well as laterally because
of torsional shock waves generated when the bit cuts into the
rock to the extent that thereby rotation is drastically slowed.
momentarily.
In the root. of the last turn of the malethread, the
stress concentration- factor can be greater than three, thus
setting an upper limit to the Allowed percussive. Stress level,
The virtually universal non-linearity of bore holes
produced with conventional drill rods in the drill String
results- in pulsating bending moments affecting the threaded
joints-. A. threaded joint has potential for high stress
concentration resulting from such bending moments. Added to
bending moment resulting from hole-deviation and human error,
premature. fatal failures occur frequently.
Finally, so-called "drilling loose" and also extensive
rattling to loosen joints- upon completion at a hole will
induce excess damage to the joint. If not performed correctly,
severe damage or even breakage can. occur,
.30 In respect of a drill rod system intending to. reduce
problems with .conVentional drill string components there has
been suggested to have the percussive shook -waves by-passing
the threads via a separate. stack of 'rodsprovided in the
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centre of a series of tubes which are interconnected with
threads. This system delivers high top-hammer penetration
rates with quality corresponding to a down-the-hole drilling
system and long service life. Because of relatively high
investment costs, this system has so far reached only a high
end market.
EP0387210 describes a background art drill string
component having a central rod surrounded by a tube.
W003097881 Al, US6293.360 and US4687368 describe threaded drill
string components. W02008/004937 Al describes a non-threaded
joint for drill string components
AIM AND MOST IMPORTANT FEATURES OF THE INVENTION
It is an aim of the present invention to provide a system
that solves or at least reduces the problems mentioned above.
This aim is obtained in a joint for joining together
drill string components for percussion drilling, wherein each
drill string component extends along an axial direction, and
wherein, in operation, impact shock waves and rotation torque
are arranged to be transferred via the joint, the joint
including a male part and a female part having meeting impact
surfaces. The invention is distinguished in - that the male
part exhibits: i, first rotation torque transfer means, and.
ii. first axial coupling means, - that the female part
exhibits: iii, second rotation torque transfer means, and iv.
second axial coupling means, - wherein the first and second
rotation torque transfer means extend on the respective male
and female parts such, and - wherein the first and second
axial coupling means are positioned such - that when the drill
string is subjected to rotation torque for drilling, relative
axial movement is allowed between the male and the female
Darts when being in an interconnected state of co-operation
between the first and second rotation torque transfer means,
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which is when the first and the second impact surfaces are
adjacent to each other.
Hereby several advantages- Over the background art are
aChieved. The invention Mg05:ea. it possible to transmit both
rotation and percussive, shock waves through the drill string
over only two meeting elements- in the joint. This is achieved
With a hole quality being comparable to. a. system as described
above (Coprod. 0), wherein transmission of rotation and of
percussive shock waves is separated in two separate elements
for each drill string component unit.
A drill string component including one or two parts of a
joint according to the invention is hereby comparatively easy
and cost-effective to produce and with- a weight being about
half that of a corresponding Coprod - element. In order to
separate the individual components, there will no longer be
reauired to rattle the drill string and. since a joint can be
produced such that bending forces are greatly reduced, the
expected working life of the components goes far beyond that
of conventional one piece drill rods.
In order to drill high quality holes there is less demand
on skilled, and experienced drillers, and altogether it has
been made possible to drill holes. of high. quality- at a low
cost.
According to the invention, the first and the second
rotation torque transfer means are laid out such as to allow a
relative axial movement, between the male. and the female parts
in the interconnected state in a region close. to where the
first and the second impact surfaces contact each other. In
particular, a minor relative displacement between the male and
female parts is allowed subsequent to an impact shock wave
passage.
The magnitude of the relative_ axial movement, or
separation between the parts of the joint is normally expected
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to be from about 0,2 to about 0,6 mm during drilling. The
separation between the parts of the joint can, however in case
of drMing in very hard rock and with a drill hammer without
damping even be expected to be as high. as between .about 1,2 -
1,6 ram. Drilling in rock- with cavities -could result in even
greater separation than that.
For that reason the joint is preferably constructed for
allowing at least 1 mm separation and .preferably 2 mm or more
of senaration. It should, however be understood that the
inventive joint can be constructed for considerably higher
degree of separation such as even up to about I00 mm.
Hereby it is avoided that high forces that otherwise
would affect the components subsequent to a percussive shock
wave passing the joint have to be received by elements of
.r threads belonging to the joint parts.
Instead these- forces are counteracted by the feed force
provided through the- drill string_ This is a great advantage,
since it is no longer necessary to dimension joint parts, such
as thread ridges, for receiving and counteracting -these
forces.. Therefore a significantly longer- service life is
possible for an inventive joint It is also possible to
produce the inventive joints for allowing certain mutual
misalignment between adjacent string components without
inducing particular bending momentscorrespondinq. to what is
being so harmful for -conventional threaded joints.
Another advantage is that the inventive joint provides.
greater energy transmission efficiency than that of
conventional threaded connections.
It is important to: understand that, during percussion
ao -drilling, the drill hammer subjects the drill string to
intense repeated impacts in. the. order of 200 MPa, whereby
shock Waves are transmitted from drill string component to
drill string component, passing via the joints of the drill
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string all the way to the drill bit. This initial shock wave
is in. the form -of a compressional wave Propagating through the
material Of the. drill string.
As a result of reflexion at the bit end of the drill
string- of the initial shock wave, either a. tensile wave or a
.compressional wave is generated propagating back through the:
drill string. Passage via a. joint of these reflected waves has
a separating effect, to Impact: surfaces of the joints.
In a threaded joint, separation is counteracted by the
thread ridges- resulting in subsequent fatigue problems and
wear. Such a threaded joint is pre-loaded. In the case of
bottom-drive the female part is in tension and the male part
Is in compression. In the case of shoulder-drive the situation
is the opposite. When an impact wave arrives, the pre-loaded
joint undergoes a partial or even a full release. Upon the
passing of the shock wave, the joint regains its full pre-
load.
The drill string is also subjected to repeated reflected
Shock waves, either tensile or compressional. These reflected
shock waves will either increase or decrease the degree of the
pre-loading, adding more releasing and reloading effect. to the
joint. The _elastic deformation associated with all these
releasing and reloading effects causes relative- movements of
the two parts being connected, but there should be no rigid
body separation between them at any time. I.e. the impact
surface of the male part is in constant contact with the
impact surface of the female part.
A feed force applied to the drill string depends on
various parameters but can be said to be in the region up to
about 5 MPa, i.e. only a minute .fraction-of the shock wave
value.
No realistic feed farce can in any joint construction.
prevent shock wive passage induced influence to the joint
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parts. According to the invention, the problem associated with
such influence is solved through the inventive completely new
approach in allowing a certain relative axial movement between
the parts. Hereby the intense but very short-lasting forces
induced by the shock wave passage can be effectively absorbed
by being counteracted by the feed force over a relatively
longer period during the relative axial movement between the
Parts.
In order to ensure that a relative axial movement between
the parts can be obtained in practice during drilling, the
Inventive joint per se is free from pretension in either
rotational or axial direction when being subjected to rotation
for drilling. Any such pretension would result in mutually
locking parts, wear because of relative micro-movements and
fatigue problems.
It is therefore important that co-operating, meeting,
surfaces of the first and second rotation torque transfer
means are arranged to contact each other in a rotational
direction such that self-locking and pretensioning of the
joint can not occur. This is achieved in that an angle between
a flank direction and a radius where the contact occurs
between two meeting surfaces of the first and second rotation
torque transfer means is great enough to avoid self-locking
and pretensioning of the joint. The angle is preferably at
least 45, more preferred over GO and most preferred over 7e.
Hereby no tendencies of self-locking occurs.
An important purpose of the first and the second axial
coupling means of the male and the female parts is basically
to ensure safe retrieval of the drill strina, It is important
to understand that in the interconnected state of two adjacent
drill string components, the first and the second axial
coupling means do not obstruct the relative axial movement
between the joint Darts. For that reason, at least in a state
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where the drill string is subjected to rotation torque or
drilling, the first and the second axial coupling means allow
and do not obstruct said relative axial movement.
With joint for joining together drill strina
COMpgnents", here- is in particular intended joints between
tubular components that Are to be positioned between a
percussive rock drilling machine and a. drill bit for
percussion drilling. since the invention is particularly
advantageous for such components. often referred. to as a drill
10. rod. This definition also includes a joint between the shank
adapter and the first drill rod.
The first and second rotation torque transfer means are
preferably mating splines that are preferably comprised, for
each one of the male and the female parts, of at least six
ac ridges that are elongated and. that extend along each one of
the. tale and the female parts, Ridges are protruding radially
inwards from an inside wall of a cylindrical member to form
female splines, Ridges. are protruding radially outwards from
an outSide wall of a cylindrical Member- to form male splines.
20 it is in principle undesirable to have rotation inducing
considerable contractive effect in the joint, because- of the
above mentioned forte reception-as well as the creation of
undesired rigidity in the joint resulting in risk of fatal
failure problems. Contacting surfaces therefore preferably
25 extend in parallel with said axial direction on the respective
male and female parts.
it is, however., in some instances advantageous to have
the contacting- surfaces extending slightly helically in the
direction of contraction on the respective male and female
30 parts of the joint when the drill string is subjected to the
normal forward- rotation during- drilling. This .contraction
must, hOWever, be limited and contacting surfaces must extend
so as ngt to prevent relative. movements between the male and
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the female joint parts which could result in tendencies of the
above problems. For that reason the. helix angle of the
contacting surfaces should preferably normally be from --20'j up
to about 200 to the axial direction. Negative values means
that separation of the impact surfaces because of the above
described effect results in. separation between meeting first
and second rotation torque transfer means.
Forming the rotation -torque transfer means, helically is
more complicated and expensive compared to forming these
surfaces axially extending, but gives a somewhat softer
rotation torque transfer between adjacent components.
The joint is obviously not ?reloaded as a conventional
threaded joint for drill string components..
In case the contacting surfaces extend axially, basically
no force inducted by the joint itself restricts, the relative
axial movement between the joint parts.
The first and second axial coupling means
advantageously include axial engagement. Means formed by
-radially directed. protrusions on one of the male and the
20. female -narts
Axial engagement_ means advantageously includes
radially -directed protrusions in the form of hook elements or
abutments on one of the male and the female parts for
engagement with abutment surface portions on the other one of
the male and the female parts. The axial engagement means are
intended for temporary axial locking so as to limit and
prevent exaggerated separation between the joint parts. One
example when this is required is for allowing: quick lifting of
the drill string for clearing the bore- hole from stuck drill
cuttings.
The axial engagement means: can be arranged such that
the first and the second axial coupling means, in an
interconnected state: of the joint,, are, made to engage in a
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positive, forward, rotation direction, i.e- in the normal
rotation direction used during rock drilling or in the
opposite, reversie, direction, whereby the connection is locked
during reverse rotation but not locked. during drilling. In the
latter case, it will not be required to have an auto rod
changer on the rig. It is also possible to have a joint
arranged for locking in both forward rotation direction and in
the opposite, reverse, direction. This embodiment is
particularly advantageous for use for a shank adapter whereby
faster operation is achieved. In all locking, axial movements
between the parts is limited according to the above.
It is preferred that one of the first and second axial
coupling means, is constituted by end surfaces of splines on
the male or female part for co-operation with the above
mentioned 'hook elements or abutments. No extra elements 11r:we
to be provided with this. embodiment.
It is preferred that the first and second axial coupling
means include axial security coupling means.. This. provides for
safe prevention against any accidental release of the joined
2.0 components. Most. preferred the axial security coupling ,means
includes a. thread coupling or a bayonet coupling.
Advantageously, second axial security coupling means
in the form. of outside threads are positioned at a distal
portion of a sleeve-shaped or rod-shaped element extending
centrally of the female part and that mating first axial
security coupling means- in the form of inside threads are
positioned at a distal portion of the male part. Suitably -a
distal. portion of the rod-shaped element is cup-shaped with
holes for flushing fluid and a rod base has holes for flushing
fluid in order to ensure advantageous fluid transfer through
the drill string duringoperation.
It Should be noted that it is advantageous to provide
the one and the same inventive joint with first and second
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axial coupling means including axial. security coupling means
as well as axial engagement means for both safe drill string
retrieval and enhanced functionality according to: the above.
The first and second axial coupling means can be arranged
in various ways and for example. as threaded means enaaging
only during a first stage of connection of two adjacent
components. Hereby, upon termination Of that first stage, free
movement along the mating first and second rotation torque
transfer means is allowed all the way to the operational
position where the impact surfaces of the two adjacent
components meet. In order to avoid that meeting end surfaces
of splines initially abut each other axially and obstruct the
connection phase, the end surfaces can be made pointed.
Aaternatively, bayonet coupling means can be used or
intermeshing books on the inside of one of the first and
second rotation torque transfer Means that engage with inside
ends of the second of the first .and the secondrotation torque
transfer means or hooks or lugs on an outside of one of the
first rotation torque transfer means for engagement with the
outside of the. other one of. the first and second. rotation
torque transfer means. Said hooks or. lugs make UD the. first
and a second axial Coupling means.
IA a preferred variant, the female part includes an
Inner and.an.outer, dual-wall construction, the walls being
sleeve-shaped together- to define an annular compartment for
the reception of a. sleeve-formed (portion of- a) male part.
The first rotation torque transfer means can be
positioned on one Of the inside and the outside of the sleeve-
formed male part, whereas the first axial coupling -means can
be positioned, on one the same side or on the opposite. side
from the first rotation torque transfer means.
It is preferred that A sealing arrangement is
positioned at an inside opening slot formed between the male
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and the female parts, as seen in an operative position with
the first and second impact surfaces close to each other.
The first and second impact surfaces can be arranged for
either shoulder drive, bottom drive or dual drive (both
shoulder and bottom drive).
For clarifying purposes: in shoulder drive, impact
surface shoulders are ring-shaped and are positioned radially
outside the first and second rotation torque transfer means
and the first and second axial coupling means.
Shoulder drive has proved to be most advantageous for
use with respect to the invention, since shoulder drive joints
tend to be less subjected to wear because the transfer of the
shock wave outside and in parallel with the portions of the
joint parts supporting the rotation transfer means. Another
2.5 important advantage with shoulder drive is that it makes it
more easy to provide for a virtually closed continuous outside
surface for the entire drill string. In particular it is
possible to make the entire drill string or at least the
regions of the joints between the individual drill string
components forming a continuous cylindrical envelope surface.
This reduces ware.
It is also important that during the small relative
axial movements in the joint in operation, impurities are
prevented to enter into the joint. The risk for that is
minimized by using shoulder drive and having mating co-
operating circular cylindrical guiding surfaces closest to the
meeting impact surfaces of two joining drill string
components. Flushing fluid leaking between the impact surfaces
when they are slightly separated adds to reduction of the risk
for impurities entering the joint.
It is advantageous in a more easily produced variant
that the female part is sleeve-shaped with one wall, having
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both the second rotation. torque transfer means and the second
axial coupling means being oriented on at inside sleeve Wall.
AdVantageously an angle between A radius of the joint
Darts and a flank direction. forming- A right angle against a
main surface of the rotation torque transfer means is 60 - 90
and more preferably 709 - 90 . Hereby unwanted self-locking of
the parts in a rotational direction is Avoided and wear during
drilling reduced to a minimum,
It is highly advantageous that the male part externally
has a proximal, cylindrical guide portion for co-operation
with. an internal, cylindrical guide surface at a distal
portion of the female part. Advantageously, the male part at a
distal region has part cylindrical outside guide surfaces for
co-operation with an internal, cylindrical guide surface at a
proximal portion of the female part. Hereby advantageous
alignment of the joint is achieved_
The invention also relates to a- male part of a joint for
joining together tubular drill. string components to be
positioned between a Percussive rock drilling. machine and -a
drill bit of a drill string for percussion drilling, wherein
each drill string component extends along an axial direction,
and wherein, in operation, impact shock waves and rotation
torque are arranged to be transferred via the joint, wherein
the male part is part of a first drill string component and is
arranged to co-operate with a female part of a second drill
string component, and wherein a- first impact surface on the
male part is arranged to co-operate with a second impact
surface. on the female. part. The inventive male part exhibits:
i. first rotation torque- transfer means, and ii. first axial
coupling means, for co-operation with iii. second rotation
torque transfer means, And iv:. second axial coupling means on
the female part, - wherein the first rotation. torque transfer
means for contacting the second rotation torque transfer means
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extend on the male part such, and - wherein the first axial
coupling means for co-operation with the second axial coupling
means is positioned such - that when the drill string is
subjected to rotation torque for drilling, relative axial
movement is allowed between the male and the female parts when
being in an interconnected state of co-operation between the
first and second rotation torque transfer means, being when
the first and the second impact surfaces are adjacent to each
other.
Preferably, the first rotation torque transfer means
are splines having contacting surfaces that extend in parallel
with said axial direction on the male part or extend helically
on the respective male parts, at a helix angle (a) between 05
and 20 to the axial direction.
Suitably, the first axial coupling means include
axial engagement means formed by radially directed protrusions
on the male part.
Preferably, the axial engagement means includes
radially directed protrusions in the form of hook elements or
abutments on the male part for engagement with abutment
surface portions on the female part.
When the male and the female parts are
interconnected, the axial engagement means are arranged to
engage in forward rotation of the drill string and/or reverse
rotation of the drill string and thereby limit relative axial
movement between the male and the female part.
Preferably, the first axial coupling means, is
constituted by end surfaces of splines on the male part.
Preferably, the first axial coupling means include
axial security coupling means. Hereby the axial security
coupling means preferably includes a thread coupling or a
bayonet coupling.
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When second axial security coupling means in the form
of outside threads are-positioned at a distal portion. of a
sleeve-shaped or rod-shaped element extending Centrally of the
female. part, mating first axial security: coupling means In the
5 form of inside. threads are advantageously positioned. at a
distal portion of the..male part.
The first rotation torque transfer means is.
preferably positioned on. one of the. inside and the outside of
the sleeve-formed male part.
10 The first axial coupling means is preferably
Positioned on one of the inside and the outside of the sleeve
formed male part.
A sealing arrangement is preferably positioned at an
inside -opening slot formed between the male and the female
15 parts, as seen in an operative position with the first and
second impact surfaces close to each Other,
The ft-rat impact surface is preferably arranged. for
one from the. group shoulder drive, bottom drive and dual
drive.
When the first impact surface is arranged for
shoulder drive, outside surfaces of' meetingdrill string
components, at least in the region .of the joint, form an
essentially continuous envelope surface.
An angle (p) between a radius (R) of the joint parts
and a flank. direction (f) forming a right angle against a main
surface of the rotation torque transfer means is preferably 60
90 and more preferably 70 - 90 .
The male part has preferably externally a proximal,
cylindrical guide portion for co-operation with an internal,
cylindrical guide surface at a distal portion of the female
part.
The male part has preferably at a distal 'region part
Cylindrical outside guide, surfaces for co-operation with an
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internal, cylindrical guide surface at a proximal portion of
the female part-
The- invention also relates to a female part of a- joint
for joining together drill string components of a drill string
for percussion drilling, wherein each drill String component.
extends along an axial direction, and. wherein, in, operation,
impact shocl.( waves and rotation torque from a percussion
drilling. machine at one end of the, drill string is arranged to
be transferred via the joint to a drill bit at an opposite end
of the drill string, wherein the female part is part of a
second drill string component and is arranged to co-Operate
with a male part of a first drill string component, wherein a
second impact surface on. the female. part is arranged to co-
operate with a first impact surface on the male part. The
inventive female part exhibits: i. second rotation torque
-transfer -means, and ii. second, axial coupling means for co-
operation with iii. first rotation torque transfer means, and
iv. first Axial coupling Means, On the tale part, - wherein
the second rotation torque transfer means for contacting the
first rotation torque transfer means extend on the female part
such, and - wherein, the second axial coupling means for .Co-
operation. with the first axial coupling means. is positioned
such - that when the drill string is subjected to rotation
torque for drilling, relative axial movement is allowed
between the male and the female parts when being in an
interconnected state of co-operation between the first and
second rotation torque transfer means, which is when the first
and the second impact surfaces are adjacent to each other.
Preferably, the second rotation torque transfer means
is splines having contacting surfaces that extend in parallel
with said axial-direction on the female part or extend
helically on 1:..he female part, at a helix angle- (o) between 0
and 2.0 to the axial direction,.
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The. second axial coupling means preferably include
axial engagement meansformed by radially directed protrusions
on one of the female parts.
The axial engagement means preferably includes
radially- directed-protrusions in the form of hook elements. or
abutments onthe female part for engagement with abutment.
surface portions one: the male part.
When the male and the female parts are
interconnected, the axial engagement means are arranged to
engage in forward rotation of the drill string and/or reverse
rotation of the drill string and thereby limit relative axial
movement between the Male and the female part.
Preferably- the second axial coupling means is
constituted by end surfaces of splines on female part.
Preferably the second axial coupling means include
axial security coupling means.
Preferably the axial security coupling means includes
a thread coupling or a bayonet coupling.
Second. axial security coupling means in the form of.
outside threads- are positioned at a distal portion of a
sleeve-Shaped Or rod-shaped element extending centrally of the.
female part for mating with. first axial security coupling
means in the form of inside threads that are positioned at a
distal portion of the male part.
The female part preferably includes an inner and an
outer wall, together defining an annular compartment for the
reception of a-sleeve-formed male part.
A sealing arrangement is preferably positioned at an
Inside opening slot formed between the male and the female
ln
parts, as Seen in an operative position with the first and.
second impact surfaces. close to each other.
The second impact surface- is arranged for one from
the: group: sbouldex drive, bottom drive and dual drive.
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When the second impact surface is arranged for
shoulder drive, outside surfaces 01 meeting drill string
components, at least in the region, of the joint, preferably
form an essentially -continuous envelope surface.
The female part is preferably sleeve.--shaped having
both the- secOnd rotation torque transfer means and the second
axial coupling means being oriented on an inside sleeve wall.
Advantageously, an Angle (0) between a radius (R) of the
joint parts and a flank direction (f) forming a right angle
against a Main surface of the rotation torque transfer means
is 60 - 90 and more preferably 70 -90.
When the male part .externally has a proximal, cylindrical
guide portion, it preferably co-operates with an internal,
cylindrical guide surface at a distal portion of the female
part.
It is preferred- that when. the male Part at a distal
region has part cylindrical outside guide .surfaces, it co-
operates with an internal, Cylindrical guide surface at a
proximal portion .of the female part.
Shoulder drive is preferred because the shock wave can be
transferred past the joint 'outside the very coupling elements
making u0 the rotation torque transfer- means and the axial
coupling means. Hereby wear is reduced .compared to what. is the
case with respect to a bottom drive solution. see also the
above for more advantages of shoulder drive.
The advantages, explained above that are relating to the
inventive ioint are correspondingly achieved in reSpect of the
male and the female parts. Subordinate optional features
relating to the inventive joint are applicable also in respect
of the inventive male and female. parts.
An inventive drill rod includes One such male part or/and.
one such female part or two sia.qh male parts or-two such female
parts.
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An inventive shank adapter for a rock drilling machine
includes one such male part or one such female part.
There are numerous ways in producing drill string
components according to the invention. One method frequently
used for producing drill rods is to friction weld the male and
female parts onto .a pipe-shaped rod blank. When it comes to
female parts having the dual-wall construction, an inner
sleeve making up the inner wall or an outer sleeve making up
the outer wall may be friction welded to a base part including
the other one of the walls.
The drill rod according to the invention is also
advantageous for use in drill strings for down the hole
hammers that produce impacts at the end of a drill string as
well as for drill strings for rotational drilling (e.g.
tricone) only.
The invention also relates to a method for joining
together tubular drill string components to be positioned
between a percussive rock drilling machine and a drill bit for
percussion drilling, wherein each drill string component
extends along an axial direction, and wherein impact shock
waves and rotation torque are transferred via a joint,
including the steps of initiating axial insertion of a male
part of a first drill string component into a female part of a
second drill string component,- rotate the first drill string
component relative to the second drill string component to
ensure engagement of axial security coupling means in the form
of a thread coupling or a bayonet coupling,- continue axial
insertion of the male part into the female part a determined
distance whereby the first drill string component is allowed
to rotate relative to the second drill string component to
ensure engagement of axial engagement means and to ensure
engagement of first and second rotation torque transfer means
arranged on the respective male and female part.
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Further details- and advantages are explained In the
-
below detailed description of embodiments.
BRIEF DESCRIPTION OF DRAWINGS
5 The invention will now be described in. greater detail at
the background of embodiments and with reference to the
annexed. drawings, wherein
Fig. 1 shows, in a simplified. side view, partly in
section, a top hammer with a drill string including -drill rods
10 and drill bit,
Figs. 2a, b and c show in axial views a first embodiment
of a joint with joint parts of a first and a second drill rod
in three different states of connection,
Fig. 2c1 shows a cross section of the first embodiment
15 and Fig. 2c2 shows in a greater scale a contact region between
two meeting splines.
Figs, 3a - d Show in different views a second embodiment
of a joint according to the invention,
Ffg 4 shows A different joint part,
20 Figs, 5a. - d show a details of different joint part in
different positions,.
Fig. f illustrates an alternatively constructed joint,
Figs. 7a and b show further different joint parts,
Figs. 8a - e show a further different joint and joint
parts,
Figs_ 9a and b show an alternative male joint part,
Figs. 10a and b show a further alternative male joint
part,
Fig. 11 shows a shank adapter in a side view.
DESCRIPTION OF EMBOD:IMENTS
Similar and like elements are indicated With same
reference numerals in different figures.
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The top hammer 1 in Fig
is movably supported by a (not
shown) feed beam of a drill rig and is arranged to deliver
impacts and a rotational movement to a drill hit 3 in order to
disintegrate rock.
A shank adapter 5, partly inside a front end region of
the top hammer 1, connects to a drill string component being a
drill rod of the drill string 2, said drill string being
composed of a number of drill string components such as
individual drill rods 4 that are connected via joints.
The drill bit 3 is connected to the lowermost drill rod 4
of the drill string 2 via a drill head 31.
An example of an inventive joint for joining together
drill rods according to the invention is shown in Figs 2a, 2b
and 2c. A first drill rod 6 has a male part 8 to be connected
to a female part 9 of a second drill rod 7. The male part 8 is
in this embodiment formed tubular as a sleeve having a free,
distal, end and a proximal end being fastened to a tubular
main Dart of the first drill rod 6"
The drill rods have an axially extending flushing channel
for allowing a flow of flushing fluid from the top hammer to
the drill bit.
The joint in Fig. 2a - c is constructed for shoulder
drive and 10 indicates a first impact surface at a shoulder
being included at a proximal end of the male part and being
directed axially for co-operation with a second impact surface
11 at a most distal end of the second drill rod 7. In this
case there is provided shoulder drive impact between the drill
rods 6 and 7 such that the impact waves pass radially outside
the elements securing connection of the drill rods to each
other.
It is also possible to have bottom drive, in which case
an alternative impact surface at the distal end of the male
part would have been arranged for co-operation with an
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alternative impact surface on fa bottom portion of) the female
part. In so called "dual drive", shoulder drive as well as
bottom drive would be active,
The male part 8 exhibits first rotation torque transfer
means being in the form of splines 12 in to this embodiment,
The splines 12 extend axially in parallel with an axis A of
the drill rods 6 and 7, and are arranged evenly distributed on
an outside surface of the sleeve-formed male part.
In an interconnected state of the male and female parts,
the first rotation torque transfer means 12 co-operate with
mating second rotation torque transfer means 14 being arranged
on an inside surface of a portion of the female part 9.
The male part 8 further includes first axial coupling
means 13 in the form of a short screw thread on an inside
surface of and at a distal region of the sleeve-formed male
part 8. The first axial coupling means 13 is arranged to co-
operate with mating second axial coupling means 15, also in
the form of a short screw thread on a portion of the female
part 9 being positioned radially inside the second rotation
torque transfer means 14 and directed radially outward..
The female part 9 in this embodiment includes two sleeve-
shaped coaxial members together forming an annular space or
compartment for more or less completely receiving the coupling
elements of the male part 8. Hereby the female part has an
inner and an outer, dual-wall construction, to define said
annular compartment for the reception of the sleeve-formed
(portion of the) male part. In the shown embodiment according
to Figs. 2e - 2c, the second axial coupling means being a
short male screw tread is arranged at a distal region of an
inner one of the sieeve-shaped coaxial members that together
forming an annular space or compartment for receiving the
coupling elements of the male part 8.
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2.3
In Fig. 2a. the male part 8 and the female part 9 are
shown in a state where the male Dart 8 has been inserted into
the annular space of the female part 9- and the first axial
coupling means 13 engage the second axial coupling means 25 by
the short screw threads being threaded together with each
other.
In the state shown in Fig. 212, the male part 8 has been.
threaded further with respect to the. femalepart 9. in that the
short screw threads being the first and second axial coupling
means. 13 and 15 have been through-threaded., passed their
relatively short axial lengths. The male part 8 can now
basically be free to. move axially Into said. annular space or
compartment being formed in the female part 9, whereupon the
splines being the first and second rotation torque transfer
means 12 and 14, can come into engagement with each other so
as to transfer rotation. torque between the first and the
second drill rods.
A state where the. first and. second rotation torque
transfer means 12 and 14 have come into engaaement with each
other is illustrated in an axial and a radial sections in Fig.
2c1 wherein the coupling. elements of the male part 8 has been
completely pushed into said annular space inside the female
part 9- such that the first and second impact surfaces 10 and
11 contact each other.
The position shown in Fig. 2c is the operative position,
wherein, during drilling, impact shock waves can be
transmitted over the joint from the first drill rod 6 to the
second drill rod 7 over the meeting impact surfaces 10 and 11.
Since the rotation torque transfer means 12 and. 14 are
also in engagement in this position, rotation induced by the
top hammer can also be transferred- from the first drill rod 6
to the second drill rod. 7..
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According to the invention it is provided that tendencies
to separate- the impact surfaces 10 and 11 occurring
immediately 'upon impact and. also upon possible shock wave
reflections passing- the joint are. not counteracted by the
elements making up the joint. On. the contrary.a relative
movement of the male part 8 and the female part 9- is possible
which Is counteracted. neither by the co-operating rotation
torque transfer means nor by the axialcoupling means.
It is also ensured, according to the invention, that
10- relative bending ofthe first and second drill rods does not
essentially affect the male and the female parts of the joint,
since also a limited relative bending movement is allowed.
Altogether, the joint parts are not at all affected by harmful
forces to the extent that normally affect joint parts of
IS background art threaded joints.
Pig. 2a illustrates a drill rod 6 being producedby a
tubular member being. friction welded together with an element
essentially making up. the male- part 8 via a -friction weld 19,
which can be produced. in a per se known. manner. 20 indicates 4
20 second friction weld between a female joint part and A similar
tubular member together making up: the second drill rod 7.
Normally a drill rod. includes. a tubular part having a
male part at one end and a female part at the other end. It
is, however, also possible that drill rods have exclusively
25 male parts or female parts at both ends.
21 indicates a third friction weld wherein the member to
be connected to the second drill Tod 7 is a part of the female
joint part only.
The steps of welding together different parts into a
30= completed drill rod is. advantageous, since a relatively small
complicated part of a component can be manufactured separately
in 4: conventional machine in a-Conventional machining process.
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Numeral 18 in Fig. 2c indicates a sealing arrangement in
the form of a sealing ring, for example of a synthetic
material, which is arranged to seal an inside opening slot 30
being formed between the two drill rods 8 and 7 during
5 operation. It is also possible to arrange a similar or
different seal at an outside opening slot being formed between
the joint parts. The sealing arrangement can be arranged with
a slit (or slits) or diminutive holes for allowing a minor
leakage of flushing fluid flowing in the central flushing
10 channel for providing limited flushing of the coupling parts
of the joint.
It is possible to arrange and position both1 the axial
coupling means and the rotation torque transfer means inverted
such that the first rotation torque transfer means are
15 arranged at the inside of the male part and the second
rotation torque transfer means are arranged at an outside of a
portion of the female part (but inside said annular space or
compartment) receiving the male part. The first axial coupling
means can be arranged at the outside of the male part and the
20 second axial coupling means at the inside of the female part.
It is also possible to arrange the female and male parts
such that both the axial coupling means and the rotation
torque transfer means of one of the parts are on the same
side. In that case, the female part can be constructed without
25 an annular space or compartment receiving the male part.
Figs. 3a d show another joint embodiment, wherein the
axial coupling means are constructed differently. As can be
seen on Fig. 3a, a male part 8 of a drill string component 6
has a plurality of axially extending splines constituting
(first) rotation torque transfer means. The plural splines are
evenly distributed around part of the length of the male part
and are adapted for co-operation with corresponding plural
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splines constituting second rotation. torque transfer means in
an inside of a female- part. (7 in Figs. 3b d).
At a distal region of the male part 8, from the. main
parts of the splines, there are radially protruding portions
32 constituting- (first) axial coupling Means. These (first)
axial coupling means in the form, of protruding portions are
adapted for co-operation between surfaces 33, :directed axially
from the distal-end of the male part, and Corresponding
surface portions 35 in a recess or recesses 34, constituting
second axial coupling means, formed inside of a mating female
part (see in particular Fig. 3d).
Fig. 3b shows the male part 8.sIightly entered into the
female part 0, the protruding portions 32 being entered
between ridges of the splines 14. Grooves between the spline
ridges are deepened and measured to allow the protruding
portions to be moved all the way to the completed
interconnected state prevailing during drilling when the
Impact surfaces 10 and 11 meet. This state is shown on Fig. Ic
and more clearly yet on the partly cut perspective view
3d. One such deepened groove is referenced- with 36 on. Fig: ad.
Figs. 3a - d basically illustrate. a variant baying a
bayonet-like coupling being used instead of a threaded
coupling making- UD the first and second axial coupling means
as illustrated in Figs. 2a -c. In order to reach the position
in Fig. 3d, after having been fully inserted Into the female
part 9, the male part 8 has been rotated such that the
surfaces 33 face the surfaces 35 inside the recess 34. Further
rotation is prevented because of contact between the splines
12 on the male part reaching contact with the splines 14
inside the female part..
The bayonet-like coupling can be arranged for
interlocking axial coupling means either as a result of
forward. rotation, used during drilling or as a_result
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reverse rotation. Interlock of the axial coupling means
results in that the drill string can be extracted from the
hole after completed drilling.
46 indicates two sealing rings that are received in
surrounding grooves being provided on a circular cylindrical
extension at a distal end region of the male joint part 8. The
sealing rings 46 constitute a sealing arrangement in this
embodiment, where the female part is of a one wall type. The
sealing rings contact and provide sealing co-operation
together with a circular cylindrical sealing surface 47 inside
a proximal portion of the female joint part 9.
In case of interlocking axial coupling means as a result
of forward rotation, used during drilling, it is important
that there is sufficient play between the surfaces 33 and 35
such that relative movement between the male and female parts
is not obstructed or even come into contact with each other
for the reasons explained above.
An important feature of the invention is shown in the
radial section Fig, 2c1, wherein an angle 0 is illustrated,
being an angle between a radius R of the joint and a flank
direction f, being a line forming a right angle against a
main, or central, flank surface of the rotation torque
transfer means (here being splines) as seen in a radial
section.
Two meeting splines are indicated 39 and 40. The radius R
extends through a contact region of meeting surfaces
contacting each other at an angle as defined above through
the region of contact between the two meeting flank surfaces
of the splines 39 and 40 and a plane SP along the surfaces at
the region of contact. A rotational direction is indicated
with RD. The angle p is great enough and preferably 45 - 90
more preferred 60 - 90 and most preferred 70 - 90 to avoid
excessive wear as well as self locking tendencies in a
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rotational d4rection when the joint is subjected to rotation
torque for drilling..
The embodiment in Figs. 2a - c is an example, wherein -a
considerable axial seoaration_of for -example 100 mm is
possible after having established the. axial cOupling through
the axial coupling means.. The. etbOdiment in Figs. 3a - d is an
example of forward locking. (locking during forward rotation),
wherein. a smaller axial separation of for example 2 - 4 nm is
possible after having established the axial locking through
the axial coupling means.
Fig. 4 shows splines 12 extending on a male part 8
forming a helix angle a with. respect to an axial direction.
This may be advantageous in order to obtain a very slight
contracting effect onto meeting drill rods as an effect of
forward rotation. The helix angle u must, however, be small
enough Such that the mutual movement between the parts is not
at all restricted or leading to wear, limited working life or
fatigue. failure.
For that reason the helix angle a must be so small that
there is no risk of inducing any self-locking effect between
the first and second rotation torque transfer Means in. order
to avoid- reduction of the beneficial effects of the invention.
This is normally achieved when the helix angle a is between 0')
and 20 .
As is illustrated in Fig. 4, for variants of splines
having a helical path, the flank direction f1 also forms an
angle a to a cross sectional plane CP through the joint part
(-s). The resulting angle of the flank direction has to be
calculated considering both a and Ø
Figs. 5a, b and c show a variant where the splines 12 on
a male part 8 are arranged with hook-like abutments. 37 for
preventing separation when the drill string components are:
rotated in one- direction. The hook-like. abutments 37 co-
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operate with contact surfaces 38 at ends of splines 14 inside
the female part 9, which is Shown partially cut, So as
together make up the. first. and the second axial coupling
means. Fig. 5b shows a relative rotational position between
the male and the female part constituting a. locked position,
where the hook -like abutments 37 corbperate with contact
surfaces 38. Pic. Sc shows, a. relative rotational position
between the male and the female part constituting an unlocked
position, where the hook-like abutments 37 are free from
contact with the contact surfaces 38.
Fig. 5d diagrammatically illustrates a further variant
where the. splines 12 on a. male part are arranged with hook-
like abutments 3.7 being completed with upstanding lugs 51 so
as to give an inverted J-shape. This prevents separation when
the drill string components are relatively rotated in both
directions when a corresponding lug 52 at the bottom end of
each female part spline 14 is engaged in a compartment limited
by the lug 51 on. the male. part.
In advantageous and preferred embodiments, the
arrahaements in FiCIS. 3a d, 4 and 5. with differently shaped
and functioning co-operating hook -like. abutments and- contact
surfaces are. combined with the arrangement described in.
relation to Figs. 2a - 2c.
One example of this is illustrated on Fig. 64 -wherein the
joint parts on the one hand are provided with short threads
13, 15 constituting first axial security coupling means on the
male part and second axial security coupling means on the
female part. furthermore) and on the other hand, there is also
arranged co-operating hook-like abutments and contact surfaces
on protruding -portions 32 and in. recesses 34 constituting
first and second axial engagement means on the male. and the
female part respectively. Hereby the combinatory effect of the
first and second axial coupling- means including axial security
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coupling means as well as axial engagement means, the
Significance of which being explained Above, is obtained_
7A And b illustrate a variant of axial coupling
means shownin Figa. 3a d being axial security coupling
5 means. After the joint parts have been rotated relative to
each -other, to. the position illustrated in Fig. 7a, and have
been axially displaced relative each other to the position
illustrated in Fig. 7b, each protruding- portion 32 is
positioned in a seat 44 having an axial stop (not shown) for
10 the protruding portion 32 and a rim element 45 preventing
unintentional rotational movement of the protruding portion 32
and thereby rotational displacement of the joint parts. During
lifting of the drill string, this embodiment provides
increased security against unintentional disassembly compared
15 to the common embodiment .of Figs. 3a - d.
When the parts are being pressed together again (back to
Fig, 7a) and the male part has been. rotated in a release
direction according -to the arrow 48 in respect of the female
part, the parts can be dismounted by the protruding portions
20 32 being free to. pass the full grooves 49 between the splines
Fig. ea shows an axial section, Fig. eb a sectioned.
perspective view and Fig Sc a cross section of an assembled
joint with the male part 8 fully inserted into the female part
25 9 and the male slines 12 in engagement with the female splines
14.
in this embodiment, a rod-shaped element 53 extends from
a rod base 55 adjoining to the: inside of the pipe-shaped part
56 of the female part. This is in Contrast to the embodiment
30 shown in Fig. 6 and described above where an inner sleeve-
shaped member of the female part at a .distal region provides a
male tread.
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Furthermore regarding the embodiment in Fig. 6a, at its
distal region, the rod -shaped element 53 is formed with a cup.
shaped. structure 54 with a cavity 57, an opening of which
facing away from the rod base. At its outside=, the cup-shaped
structure 54 carries a male thread 60 being female part
(second) axial security coupling means of the second axial
coupling means.
The cup. shaped structure 54 is provided with a plurality
of first through holes 58 for flushing fluid. The rod base,
which extends from the rod-shaped element radially outwards to
pass over to the inside of the tubular outside of the pipe-
shaped part 56, is provided with a plurality of second through
holes 59 for flushing fluid.
The male part B. exhibits a sleeve shape and extends from
a proximal region being adjoining to the evenly pipe-shaped
part of a drill string component to a distal region having on
its inside a female thread 61 corresponding to the male thread
60 (male part (first) axial security coupling means of the
first axial coupling means) together forming the axial
security coupling means of the second axial coupling means.
The passage between the female thread 61, the inside 62 of the
sleeve shape and the outside surface of the rod-shaped
elements form together with the holes 58 and 59 an effective
flushing fluid path. During operation, small amounts of
flushing fluid leaks out in each and every joint passed the
splines 22, 14 for cooling purposes, and out between a an
outside surface of a cylindrical guiding part 63 most proximal
on the on the male part and an inside surface of a cylindrical
guiding part 64 most distal on the on pipe-shaped part of the
female part and subsequently between shoulder contact surfaces
at 65 between impacts.
These inside and outside surfaces 63 and 64 of the male
and the female parts respectively contribute to the alignment
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of the joint during operation. Furthermore, alignment of the
loint is also advantageously effected through. cooperation
beween radially outwardly directed surfaces 72 on the.
abutments 37- and an inside surface 71 inside the pipe-Shaped.
part of the female part (see- Figs. 8a, ae, 9b .and 10b). The
radially outwardly directed surfaces 72 of the abutments 37
together form an interrupted annular envelope surface.
Ensuring proper contact be.twen the surfaces 71 and 72
can be arranged by having a slightly smaller inside diameter
of a portion of the female part forming the inside surface 71.
Ensuring proper contact between the surfaces 71 and 72 can
alternatively be arranged' by having a slightly larger outside
diameter of the abutments' (and the radially outwardly directed
surfaces 72).
This combined guiding arrangement at two axially
separated positions Of the joint is advantageous- for achieving
stable alignment.
The complete female partincludes a rod portion
comprising the rod-shaped element 53, the rod base 55 and a
portion 56' of the pipe-shaped part as shown in Fig ad
together with a continuation 56' of the pipe-shaped part as
shown in Fig Be. The. portion 56' is friction welded at 66'
to a meeting surface at 66' of the continuation 56-- to form
weld 66 of the complete female part. The female part is
subsequently in turn friction welded to a pipe of the drill
string component.
Furthermore, inside the continuation 56"' there are
positioned female pert splines 14 At the inside end of each
sline 14 there are provided contact. surfaces 38 constituting
20 female Dart axial engagement means (compare. 38 in Figs. 5a
u)
Figs. 9a and b illustrates the male Dart of the
embodiment of Fig. 8a. From the side view in Fig. 9b is
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evident that abutments 37 are arranged free from the splines
such= that an annular groove can be said to be provided
therebetween. This facilitates production and fine machining
of contact surfaces on the abutments 37. The contact surfaces
37 are arranged for engagement in one rotational direction
only with contact surfaces 38 constituting female part axial
engagement means (see Fig. 8e), It is referred to the
description above of different elements for full understanding
of the male part. The male part is friction welded to a pipe
forming the main part of a drill string component.
Figs. 10a and b illustrates an alternatively configured
male part. From the side view in Fig. 9.b is evident that
abutments 37 have contact surfaces 37- are arranged for
engagement in a first rotational direction with contact
surfaces 38 constituting female part axial engagement means
(see Fig. 8e). This alternatively configured male part,
however, has abutments 37 arranged so as to have contact
surfaces 37¨ that are arranged for engagement also in a
second rotational direction with contact surfaces 38
constituting female part axial engagement means (see Fig. 8eh
Furthermore, in this male part embodiment, there is no
Inner female thread making up a male part axial security
coupling means most distally inside the surface 62. Axial
engagement thus relies fully on the axial engagement means.
The embodiment in Figs. 10a and b is particularly
applicable for a shank adapter 67, see Fig. 11, where axial
security coupling means would be an obstacle because of the
repeated assembly, disassembly taking place between the shank
adapter and the most adjacent drill string component. 66
indicates a male part as shown and described with reference to
Figs. 10a and b. 69 indicates a drilling machine end of the
shank adapter and 70 indicates an inside component of =a
swivel.
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It is possible to use other means preventing rotation
between interconnected parts besides splines as first and
second rotation torque transfer means. Basically,
interconnected parts: having rotation preventing means- that
engage each other can be made in various configurations when
they fulfil the: requirements explained above. Use of splines
is, however, preferred. for a-number of reasons such as ease. of
production and reliability.. The number of splines can be
adapted to the situation and if the joint parts have to he
relatively rotated for Achieving axial locking. The. axial
length of the splines is chosen so as to reach an acceptable
surface load on the flanks of the splines.
The embodiments shown in the Figs illustrate drill
strings having the male joint part of a joint being- carried by
a drill string component being closest to the drill hammer but
it should be evident that the Opposite situation -with the
female joint part being carried by the drill string component
being closest to the drill hammer Is fully. possible.
The term comprised is here. intended as an open (Aurid not
closed) definition which is not restricted to the feature
following the term Also other features can be present.
