Note: Descriptions are shown in the official language in which they were submitted.
CA 02219893 1997-10-30
W O9'~Q3~ PCTISE9S/0048S
Threaded co~rl ~t~g, male and female e~ctF~-n~iQn O
as well as a method of maint~n~tlE~ a threaded coupling
The present invention relates to a threaded coupling b~ Lw~ a female extencion
member and a male extension member in a drill string for pc,~;u~ e drilling,
5 said female e~t~ncion memher being provided with an intern~l thread, said maleextension member being provided with an extern~l thread, said intern~l and
e~t~rn~l threads lc~e~Liv~ly being (l~cign~l for engagement with each other.
The present invention also relates to the female extension member per se, the
male extenci~ n member per se and a method of m~ a coupling bcLw~e
10 a female extension member and a male extension member for ~ e
rlrilling
Especially for tubes for p~..;ussi~e drilling it is pFeviously known to use so-
called male-female thread couplings, i.e. an e~tern~lly threaded spigot, that is15 integral ~,vith a tube element, coo~,ldLes with an int~rn~lly threaded sleeve, that
is integral with an ~diacent tube element. When a shock wave reaches the
coupling, said shock wave is instantly affected by the (1imenciol~l variations in
the coupling, e.g. change in wall thicknesc of the tube element. These variations
give rise to reflecting waves that propagate in the tube elennent in the opposite
20 direction of the shock wave. Due to the fact that both the spigot and the sleeve
are inteEr~l with the ~ clont tube eletnentc, the abutting thread flanks of the
spigot and the sleeve will be subjected to considerable impact when the shock
wave is tr~n~mitte-d between the abutting thread flanks. Such an impact
n~rm~lly gives rise to wearing and pitting
Also previously known are ext~orn~lly threaded coupling sleeves, applied
int.orn~lly in ~dj~c~nt ends of two e ctencion tubes. Said coupling sleeves are
superior as regards the tr~ncmiccion of impact energy co~ ued to the prior artmale-female couplings mentioned above. Since the intet~n~l coupling sleeve is a
30 s~Udl~ detail it will only be ",a,~""ally affected when the shock wave
bypasses the thread coupling. Also the ~limencions~ i.e. the wall thickness, of
CA 02219893 1997-10-30
WO g~ 5038 PCI~ h~s~'~!Ql4~!;
the tubes can be kept constant in the thread coupling. However, one problem
with intPrn~lly applied coupling sleeves is that when disconneting two tubes
connected by such intern~lly applied coupling sleeves it is impossible to control
in which tube the sleeve will remain. This is a great disadvantage in connectionS with ~lltorn~ti7Pd h~n~llin~ of the tubes.
.
From SE-B-470 217 a device for yieldably locking a threaded spigot in a
threaded boring is previously known, said device being a ring of urethane
rubber that provides a friction action between the spigot and the boring during
10 ~lrilling It has turned out that this device ~ ro~ s well in surface drilling,
since the flushing medium normally used is air holding a certain amount of
powdered cuttings. This means that the spigotlboring coupling will adopt a
relatively high t~ tldl~e and consequently the waxing of the rubber ring will
dis~pedl by drying. The rubber ring is almost vnl~ni7ed to the spigot.
When the device according to SE-B-470 217 is used in underground drilling the
function is negatively affected, prim~rily due to the fact that water norm~lly is
used as fln~hin~ medium. The consequence of using water instead of air is that
the temperature of the spigot/boring coupling is lower and the wax remains on
20 the rubber ring. Thus the rubber ring exerts very little friction action upon the
spigotlboring coupling. This means that there is no erre~;live control that the
int~rn~lly applied sleeve will be m~int~inP~l in a certain tube cle .~ by the
rubber ring.
25 A joint for steel pipes for oil transport is previously known through US-A-4
426 105, in which a ring locks male and female parts together. If that joint wasto be used for ~Jel~;US::iiVt; drilling the ring would almost imm~ tely, after acouple of blows, be sheared off along a path colle~onding to the outer
h~l~ of the male member. That is bec~use the male m~mber is more
30 axially movable than is the ring.
CA 02219893 1997-10-30
W O~f'35038 P~l/~S/'~C1~5
One object of the present invention is to present a concept that will work both
for surface drilling and underground drilling, i.e. to secure safely the int~rn~lly
applied coupling sleeve in one of two adjacent drilling tubes. Another object of~ the present invention is to present a concept wherein the intPrn~lly applied
S coupling sleeve is pPrmAnPntly secured in one of two ~rljA~Pnt drilling tubes.
The objects of the invention are realized by a coupling, a coupling sleeve, a
female extension member and a method, res~c~;lively, that has been given the
char~cteri~tics of the appending claims.
Below, ~l~r~ d embo~limPnt~ of the invention will be described, reference
being made to the accompanying drawings wL~,.eill Fig. 1 shows a partly
sectioned side view of a coupling according to the present invention beLW~;e11
two tubes for ~c,~;u~ e drilling mounted for drilling purposes; Fig. 2 shows a
15 detail of one end of the coupling sleeve in drilling position; Fig. 2A shows a
partly sectioned side view of an ~ltPrn~tive embodiment of a coupling according
to the present invention in unscrewing position; Figs. 3a-3c show the locking
ring per se; Fig. 4 shows a coupling accordil g to the present invention betweentwo members forming a shank adapter.
A coupling is shown in a mounted position with a non-operative position of
locking means in Fig. 1. The coupling inclll(les a first end portion 10 of a first
çxtPnxion drilling tube 12 and a second end portion 14 of a second Pxt~Pn~ion
drilling tube 16, the free ends of said end portions 10 and 14 abutting each
25 other. The first end portion 10 is provided with a first intPrnAl cylin-lriçAl
thread 18 and the second end portion 14 is provided with a second intern~l
thread 20.
The first intPrn~l thread 18 is tPrmin~te-l by a first Cil~;u llfc.~;llLial cle~c~ ~ce 22.
30 A(lj~cent to the first çleArAnre 22, but further away from the free end of the end
portion 10, an intPrn~l ci~.;u l.fc._llLial first groove 24 is provided, see also Fig.
I
CA 022l9893 l997-lO-30
W 096/35038 PCT/~h~S/~
2, said first groove 24 receiving a locking ring 25, preferably made out of
spring steel. As can be learnt from Figs. 3a and 3b the locking ring 25 has a
circumferential gap 27 of a certain width. Due to the gap 27 it is possible to
reduce the diameter of the locking ring 25 when mounting said locking ring 25
in the first groove 24. Still further away from the free end of the end portion
10 a first reskictiQn 23 is provided, said reskiction 23 forming a first shoulder
29, the function of which will be described below.
The second int~rn~l cylindrical thread 20 is also t~rmin~tP~l by a second
clearance 26 that in its turn is termin~te~l by a second reskiction 28, said
second reskiction 28 forming a second shoulder 30, the function of which will
be described below.
The coupling according to the present invention also includes an internal
coupling sleeve 32 that is provided with an e~tem~l cylindrical thread 34. The
coupling sleeve 32 has a lon~it~ in~l~ through-going, internal boring 36 to
allow flushing mç~ m to bypass the coupling. As can be seen in Fig. 1 the
wall thickn~c~ of the coupling sleeve 32 co~tin~ n~ly increases from both ends
towards an int.~rme~ te portion of the coupling sleeve 32. In the int~rme~ tç
portion the wall thickness of the coupling sleeve 32 is constant. At one end of
the coupling sleeve 32 an t-xt~m~l second circurnferential groove 38, see Fig. 2,
is provided. The free end of the coupling sleeve 32 ~ cçnt to the second
groove 38 is in the shape of a first bevelled portion 40. Between the first
bevelled portion 40 and the second groove 38 a cylinrlric~l portion 39 is
provided. At the opposite end the coupling sleeve 32 also has a free end in the
shape of a second bevelled portion 42.
In order to safely secure the coupling sleeve 32 in the first drilling tube 12 the
end of the coupling sleeve 32 carrying the second groove 38 is threaded into
the end portion 10 of the first drilling tube 12, i.e. the e~t~ms~l thread 34 of the
coupling sleeve 32 engages the first internal thread 18 of the first drilling tube
CA 02219893 1997-10-30
W O~f~3~ SJ~
12. When the first bevelled portion 40 ~ ctont to the second groove 38
contacts the locking ring 25, said bevelled portion 40 forces the ring 25 against
the far side wall 24a of the first groove 24, seen in the direction of
displacement of the coupling sleeve 32. Further displ~r~ment inwardly of the
coupling sleeve 32, i.e. to the left in Fig. 1, will expand the ring 25 due to the
circurnferential gap. The ring 25 will climb the bevelled portion 40 further as
the coupling sleeve 32 is displaced inwardly. Eventually, the locking ring 25
reaches the cylin~lric~l portion 39 b~,lw~ - the bevelled portion 40 and the
second groove 38. The locking ring 25 byp~ses also said cylindrical portion 39
when the coupling sleeve 32 is displaced further inwardly and finally the
locking ring 25 reaches the second groove 38 and is snapped into said second
groove 38. The locking ring 25 is now safely secured in the second groove 38.
The play bclwccll the width of the groove 38 and the width W of the ring 25,
see Fig. 3c, is preferably about 10% of the width of the groove 38. Preferably,
the thickn~s~ T of the lock~ng ring 25, see Fig. 3c, is about half the width W.
The thicL n~e~ T of the locking ring 25 exceerl~ the depth of the second groove
38, i.e. when the locking ring 25 is ~ ly mounted in the second groove 38
the locking ring 25 loYt~-n~ki beyond the outer periphery of the adjacent end ofthe coupling sleeve 32. As is evident from Fig. 1 the locking ring 25 will neverabut the side walls 24a and 24b of the first groove 24 when the coupling sleeve
32 is ~ pl~cecl loI git~ innlly in either direction during ~lrilling This means that
the axial play L1 1)CLWCC11 the sleeve 32 and the female parts 12 and 16 is
smaller than the axial extension L2 of the groove 24. Thus, the coupling sleeve
32 is p~o~ ly secured in the first end portion 10 of the first drilling tube 12.However during U~lSclc~ g of the coupling the ring will move axially the
lliet~n~e L2 and contact the side wall 24b and thus stop further UllSc~ g of
tha tparticular end of the male eYton~i( n member so that further ~scl~ g
will take place at the axially opposite end of the male ~t~n~ion member.
~ In Fig. 2 an hltern~tive cross-section of the locking ring 25 is shown with
CA 02219893 1997-10-30
W O9''3~0~ PCT/~hg5~Q48
dotted lines. In such a case the side wall 24b should be inclin~d in accordance
with the dotted straight line. By such an arrangement the inclined side wall will
force the locking ring 25 down into the second groove 38 when contact is
established between said locking ring 25 and said inclined side wall.
s
When the coupling sleeve 32 is ~loptlly secured in the first drilling tube 12
about half the length of the coupling sleeve 32 projects from said first drilling
tube 12. To couple together the first drilling tube 12 and the second drilling
tube 16, said second drilling tube 16 is threaded on the coupling sleeve 32, i.e.
10 the int~rn~l thread 20 of the second drilling tube 16 engages the ~xtçrn:~l thread
34 of the coupling sleeve 32. When the free ends of the first and second
drilling tubes 12 and 16, respectively, abut each other a proper coupling is
established and the percussive energy is transfered between adjacent drilling
tubes 12 and 16 through the abutting free ends.
The first and second shoulders 29 and 30, l~sL,e-;Li~ely, col ~tit~lte longit~l~lin~
stops for the ends of the internal coupling sleeve 32. These shoulders prevent
the ring from being cont~rt~d by the first drilling tube 12, since the ring cannot
stand many blows during drilling. ~ltern~tively the stops could be made at
20 another part, i.e. close to the free end of the first drilling tube 12.
Within the scope of the present invention it is possible to mount a ring of
u~ ~le rubber accordLIg to SE-B-470 217 in the clearance 22. An additional
securing of the coupling sleeve 32 is thus achieved, at least for surface tlrilling
Another favourable feature of the present invention is that it is possible to use
dirrt;l~;,lL m~teri~l~ or m~tPri~l~ of dirr~.e.lL heat tre~tm~nt in the drilling tubes
12 and 16 on the one hand and the coupling sleeve 32 on the other hand. Such
an arrangement o~Lhlli~s the life of the coupling since the drilling tubes 12 and
30 16 are subjected to a faster wearing, i.e. both the ~xt~rn~l ~ .;pll. ;es and the
int~rn~l threads 18 and 20, res~e.iLively. Therefore, the material in the coupling
CA 02219893 1997-10-30
W 096/35038 PCT/~5S~'~0~8S
sleeve 32 should preferably be softer than the material in the drilling tubes 12and 16.
In Fig. 2A an ~ltern~tive embodirnent of a concept according to the present
S invention is shown. A coupling is shown during ullsc~ vhlg with an operative
position of locking means. The threads 18' and 20' is in principle cleei~n~l in a
way corresponding to the threads 18 and 20, lc;,~e-;Li~ely, disclosed in Figs. 1and 2 of the present application.
However in this embodiment the first internal thread 18' is not Ir~ 1 in a
clearance but in a mainly cylin-iric~l surface 22', preferably ece.onti~lly
coinciding with the smallest diameter of the thread 18'. Adj~ent to the
cylindrical surface 22', but further away from the free end of the end portion of
the first drilling tube 12', an int~rn~l circumferential first groove 24' is
provided. The first groove 24' receives a locking ring 25', preferably made of
steel such as a spring steel, (lecignP~l similar to the ring 25 described in
cormection with Figs. 2, 3a and 3b, but with convex side walls. The ring may
~lt~rn~tively have a round or square cross-section and then the conn~cte~l
grooves should be adapted thereto. At one end of the coupling sleeve 32' an
external second circumferential groove 38' is provided. The free end of the
coupling sleeve 32' ~ tont to the second groove 38' is in the shape of a first
bevelled portion 40'. Between the first bevelled portion 40' and the second
groove 38' a cylindrical portion 39' is provided. At the opposite end the
coupling sleeve 32' also has a free end in the shape of a bevelled portion. The
bottom of the groove 38' compriees a first portion 138' of generally smaller
met~r than a second portion 238' thereof. The first portion 138' is arranged
at a larger ~liet~n~e from the free end of the sleeve 32' than is the second
portion 238'. The second portion 238' sucessiveiy reduces the radial depth from
the first portion to the cylindrical portion 39' via a wedge or r~ leee~1 shape.~lt~ rely the second portion may be cylin-lric~l but with a greater radius
than the first portion.
CA 02219893 1997-10-30
W Og6/~3~ PCT/SE95/00485
The thickness of the locking ring 25' is smaller or mainly similar to the depth
of the first portion 138' of the second groove 38', i.e. when the locking ring
25' is properly mounted in the second groove 38' the locking ring 25' falls
radially below or is mainly flush with the outer periphery of the adjacent
S cylindrical surface 139' of the coupling sleeve 32'. As is evident from Fig. 2A
the locking ring 25' will abut the side walls of the first groove 24' when the
coupling sleeve 32' is ~li~l~re(l longitudinally in either direction. Thus, the
coupling sleeve 32' is ,~,lo~ e-ly secured in the first end portion of the firstdrilling tube 12'. The play between the width of the groove 24' and the width
of the ring 25' is preferably about 10% of the width of the groove 24'.
Preferably, the thickness of the locking ring 25', see Fig. 3c, is about half the
width. The width of the groove 38' is at least 50 % larger than the width of thering 25'.
IS The thickness of the locking ring 25' exceeds the depth of the second groove
portion 238', i.e. when the locking ring 25' is plop~lly mounted in the second
groove 38' the locking ring 25 extends generally beyond the outer periphery
39' and 139' of the ~ cent end of the coupling sleeve 32' after having been
co~ lessed into groove portion 138'. The sleeve 32' is axially movable a
20 ~ t~n~e L2' relative to the tube 12' during ulls~ g of the coupling. The
t~nre L2' is larger than the distance Ll, described in cormection with the
former embo-lim~nt That is to avoid blows on the locking means during
drilling.
25 In order to safely secure the coupling sleeve 32' in the first drilling tube 12'
the end of the coupling sleeve 32', carrying the second groove 38' in which the
ring 24' is accomodated in the deeper first portion 138', is threaded into the
end portion of the first drilling tube 12', i.e. the ~t~ l thread of the coupling
sleeve 32' engages the first internal thread of the first drilling tube 12'. When
30 the radially outer periphery of the ring, in colllplessed state, contacts theint~rn~l thread the ring will remain in the portion 138' until it is allowed to
CA 02219893 1997-10-30
W O~,13C~ PcT/~
~ n~l F.xr~n~ior~ occurs when the ring reaches the first groove 24' and
further insertion of the sleeve will became impossible due to cooperation of theside wall of the groove 24', the ring 25' and a side wall 338' of the groove
38'. The ring 25' has two positions in the groove 38', that is the assembly
5 position in radially com~lcssed state at the portion 138' and a locking position
when the ring has snapped into the groove 24'. When the ring is in the groove
24' and the sleeve is screwed axially outwardly towards the free end of the first
end portion the second portion 238' will wedge up against the ring as in Fig.
2A to prevent further outwardly directed movement of the sleeve 32'. The
10 sleeve however, may move axially in the opposite direction a ~ t~nee generally
corresponding to the axial extension of the portion 138'. Once the ring has
snapped into the groove 24' it will be stuck therein preferably still in a
colllplessed state and will provide a ~ lock for the sleeve 32'. By the
term ~'pçrrn~nPnt~ or "pe~n~nPntly" is meant that the ring cannot be dismounted
15 without de~Llvyillg the ring, for e~mrle by tllrnin~- The second portion 238' of
the groove may instead of a being defined by a wedging conical shape or a
radiussed section, be cylindrical but with a larger radius than the first portion
138'. That is to provide for just enough space for the ring between the parts 12'
and 32' and to additionally secure the ring in the groove 24'. Thus, the
20 coupling sleeve 32' is pçrm~nPntly secured in the first end portion of the first
drilling tube 12'.
Although the embotliment~ according to Figs. 1, 2 and 2A refer to a threaded
coupling between two tubes in a drill string the threaded coupling according to
25 the present invention also is applicable in a threaded coupling 1)C;LW~;;e11 a
tube/rod and a drill bit for percussive ~lrillinp
In Fig. 4 a shank adapter 44 is ~liclose~l said shank adapter incl~ ing two
sepa~dl~ parts, i.e. a shank part 46 and a sleeve part 48. The shank part 46 is at
30 one end provided with a boring 50 having an int~rn~l thread 51 and at the other
end with a head portion carrying splines 52, said head portion being adapted to
CA 02219893 1997-10-30
W 096/3S038 PCT/SE9S/00485
be inserted in a top h~mmer rock drilling m~hine. The internal thread 51 is in
principle cleci~nP~l in a way corresponding to the internal thread 18 disclosed in
Figs. 1 and 2 of the present application.
5 The sleeve part 48 is provided with an ~xt~rn~l thread 54 adapted to be in
engagement with the internal thread 51 of the boring 50 when the shank adapter
44 is in working condition. The çxt~rn~l thread 54 extends along the entire
length of the sleeve part 48 and preferably the external thread 54 has the sarnedesign along the entire length of the sleeve part 48. The sleeve part 48 is
10 further provided with a through-going internal boring 56 that is clesign~l in a
way corresponding to the internal boring 36 of the coupling sleeve 32 of the
embodiment of Figs. 1 and 2 of the present application. In the area of the end
of the sleeve part 48 that is inserted into the boring 50 means are provided foraxially locking the sleeve part 48 in the boring 50. Said means in principle
15 co,~ ol,d to the axially locking means of the embodiment according to Figs. 1and 2 of the present application, i.e. said inserted end of the sleeve part 48 is
provided with a locking ring 58 that is mounted in a circumferential groove 60
of the boring 50. When the inserted end of the sleeve part 48 reaches the
locking ring 58 said ring will also cooperate with a circumferential groove on
20 the sleeve part 48. In principle the axially locking of the sleeve part 48 in the
boring 50 is effected in a way collG~ollding to the axially locking of the
coupling sleeve 32 in the first end portion 10 of the first drilling tube 12
according to the embodiment shown in Figs. 1 and 2 of the present application.
Thc~,rore, in t,hat respect reference is made to relevant portions of the
25 description of the present application.
The t~t~rn~l thread 54 of t,he end of the sleeve part 48 protruding from the
shank part 46 is in working condition connecte~l with an intern~l thread of a
first tube/rod of a drill string for pe.~;ussiv-e ~lrillin~ Thereby the free end of
30 the shank part 46 abuts the free end of the first tube/rod and the pel~;ùs~i~e
energy is transferred via said abutting ends, i.e. the transfer of pc~;us~ive
CA 02219893 1997-10-30
WO 9fiJ~5~X PCT/SE9SI0048S
energ,v is effected in the same way ~ for the embodiment according to Figs. 1
and 2 of the present application.
'' Common for the above-described embodiments of the present invention is that
5 when ul~s~ilc~ing the male extension member from the female extension
member, the male.~lrten~ion member moves a limited ~ t~nre relative to the
female extension member until it is stopped by means 24,25,38;24',25'38' for
axially locking the male exten~iorl member 32;32';48. This means that the male
extension member during drilling is movable a first ~ t~nee Ll relative to the
female extension member 12;12';46 and that the means 24,25,38;24',25'38' are
ol el~live during ~ scLc~ving when the male extension member is moved a
second distance L2;L2' relative to the female extension member, wherein said
first distance Ll is smaller than said second rli~nee L2;L2'.
