Note: Descriptions are shown in the official language in which they were submitted.
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BACKCROUND OF T~l~ INVE~TION
The present invention relates to drilling in general and
to repal~able stabilizer f~r uqe in a drill string in particular.
In the drilling of the earth it has been well known to
utilize stabilizers or reamers which are connected in the drill
string and rotate therewith. The stabili~er is often positioned
near ~he bit and since it has portions contacting -the inside sur-
~ace of the drill hole it will prevent the bit from wobbling,
thereby ensuring the drilling of a straight hole and prolonging
the life of the drill bit. Such stabilizers usually include a
plurality of circumferentially spaced, cylindrical stabilizer
members each rotatably mounted on a shaft ~n the stabilizer body,
having a plurality of radially projecting tungsten carbide pellets
on the outer surface thereof and having a longitudlnal portion
thereof lying outside the stabilizer body. As the pellets wear
during use of such stabilizers their effectiveness decreases and
it becomes necessary to replace the stabilizer with a new one.
The drill bit must be withdrawn from the bore hole, the stabilizer
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removed, a new one attached and the drill string ~eassembled.
' 1 20 During operation of ~he stabilizer it is recessary to
supply the drill bit, the stabilizer members and the shafts with -~
lubricant. Drill fluid, such as air, is used and it is often
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supplied by an intricate series of groo~es and passages formed in
' 1 the various structural members. This, of cours~, increases the
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m~nufacturing costs Eor a stabilizer. In addition there should be,
and often i8 not, provision fo~ the removal of any debris that
might be picked up-by the rotating stabilizer member and brought
. in~o the pocket ln the stabilizer body in which the rotary members
reside. Debris can reduce the effectiveness of the stabilizer by
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`~r~asing the w~r on thc ~ s, c~usin~ ~tructural clanlag~ or
even jamming th~ rotary m~mbcr ayainst rotational movement.
Such prior art stabilizers also encountered difficulty in
accommodating axial loads. The loads, often as not, were suskained
via a bearing surface between the end face o~ the roller its~lf and
its mounting portion. This type of bearing was also prone to wear
due to grit and other particles being entrapped in the bearing area,
- a situation which was not overcome by the prior lubricating systems.
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`` A typical weak characteristic of prior art stabilizers is
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~ 10 more rapid wear at the box end than along the rest o the stabilizer
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body. Since most prior art stabilizers utiliæe unitary bodies,
meaning that the main body portion and the pin and box ends are
- machined from a single blank, wear of the box end will necessitate
replacement of the entire body, a considerable waste and expense.
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SUMMARY OF THE INVENTION
The present invention overcomes the above difficulties in
a novel manner. Wear in the roller assemblies is accommodated by
~' using replaceable assemblies and by maximizing the roller diameter
to reduce overall contact time between any pellet and the drill
~"' 20 hole wall. The problem of wear at the box or pin end is overcome
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by constructing these ends as separate pieces and then connecting
them to the main body section so tihat tney can ~e replacea iE
necessary. A curved shield or tray member surrounds each roller
and aid~ in containing the lubricating fluid within the stabilizer
body while ensuring proper alignment of a roller sub-assembly
should such be replaced during the life of the stabilizer.
In its broadest form, therefore, the present invention
provides a rotary stabi~ izer assembly for reception in a compatible
receptacle in a stabilizer body, comprising a generally cylindrical
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shaEt having an axial bore therethrough, a generally cyI:indrical
roller stabilizer member rot2table on the shaft, a pair of mo~nting
blocks, each being affixed to a corresponding end oE the sha~t and
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havlng a bore communicatLng with the axial bore, and a tray member
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~ extending between the mounting blocks, the t~ay member partially
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surrounding the roller member to expose a longitudinal portion of
the ou~er surface thereof.
The present invention may also be defined as a rotary
stabiliæer for connection in a drill string comprising: a general~y
, 10 cylindrical stabilizer body having passage means -therein for the
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passage of drill fluid, a plurality of circumferentially spaced
, longitudinally directed receptacles in the body, each receptacle
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` being adapted to receive a removable rotary stabilizer assembly
;1 therein, and the assembly including a generally cylindrical shaft ~;
having an axial bore therethrough, a generally cylindrical roller
D stabilizer member rotatable on the shaft, a pair oE mounting blocks,
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1, each being affixed to a corresponding end of the shaft and ha~ing
a bore for communicating the passage means with the axial bore,
3~ and:a tray member extending between the mounting blocks, the ~ray
member partially surrounding the roller member to expose a
longitudinal portion of the outer surface thereof.
~:J~ ~ BRI~F DESCRIPTION OF THE DRA~INGS
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An embodiment of the present invention will be described
in detail wlth reference to the ac~ompanying drawings wherein:
Figure 1 is an isometric view of a stabilizer incorporating
the pres-ent invention,
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~ Figure 2 is an exploded view showing the pin end, ~ain
r~ ;; body and box end of the stabilizer,
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Figur~ 3 is a cross-section taken alonfJ thc line 3-3 of
Figure l;
Figure 4 i5 an exploded vi~w showing the various compon~nts
; making up the rollex sub-assembly, and
Figure 5 is an isometric view of the complete roller assemhly.
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DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 illustrates an assembled roller stabilizer
` according to the present invention, the stabilizer being identified
by reference number 10. ~s seen in Figure 1 the stabilizer includes
a pin end 12, a box end 14 an~ a main body 16 which in turn mounts,
in this instance, three circumferentially spaced roller assemblies
-~ 18 only one of which is shown in Figure 1.
Figure 2 illustrates the component parts which constitute
the overall stabilizer body absent, of course, the roller assemblies.
The main body 16 is generally cylindrical in form and is provided
with an axial bore 20 which extends from end to end thereof. Each
end of body 16 has a face 22 which slopes slightly axially out-
~j wardly towards the central axis A and terminates in an outwardly
,~/ projecting annular flange 24, the purpose of which will shortly
,~ 20 be clarified. Circumerentially spaced about the body 16 is a
;`;' plurality of opanings or receptacles 26, generally rectangular
i in outline which extend through the wall of body 16 tc the centr~l
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bore 20. Bach opening 26 is sized to receive a roller assembly
; 18 as wi.ll eventually become evident.
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The pin end 12 includes a cylindrical body portion 28having formed therin a pair of diametrically opposed sockets 30
which can receive an appropriately sized wrench used for screwing
'~ or unscrewing the stabilizer to or from the box end of an adjacent
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drill ~ring, The p:Ln ~n~ is also provided wlth the usual mal~
threaded portion 32 for r~ceptlon in the box end of the ad~acent
` drill strlng. A~ axially directed bore 34 through the pin end is
intended to be coaxial wlth bore 20 in the main body 16.
.. The end face of the pin end 12 opposite threaded portion 34
is formed in exactly the sa~e manner as the adjacent end of main
~- body 16. Thus, when the flange 24 of the pin end is brought into
abutting alignment with the flange 24 of the main body 16 ~he
opposed sloping faces 22 will form a radially outwardly diverging
~: 10 annular groove which may be filled with weld material 36 (Figure 1
.;. whereby the pin end 12 may be removably, yet solidly, connected to
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` the main body 16.
~ The box end 14 inc~udes a generally cylindrical body
li portio~ 38 provided with an axially extending through bore 40
~.~ intended to be coaxial with bores 20 and 34, respectively. The end
: face adjacent main body 16 is identical to the adjacent end of the
main body whereby the circumferential groove formed when the box
end is brought into abutting alignment with the main body may be
filled with weld material 42 (Figure 1) to provide the removable,
~. 20 yet solid, connection of the box end 14 with the ~ain body 16.
; 1 Needless to say the box end 14 has an appropriate female
threaded bore therein for reception of the pin end of the ad~acent
drill string. Finally, as is readily apparent from the drawings,
the box end, pin end and main body have a uniform outside diameter.
i'`;'~ ~ The rotary or roller assembly 18 adapted for reception in
opening 26 will now be described with referPnces ~o Figures 4 and 5
A roller stabilizer member 44 is provided, generally cylindrical
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in shape, and has an axial bore 46. As i9 well known in the art
~i~ the roller 44 is provided with a plurality of tungsten carbide
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m~r p~ ts ~8 uniformly di.stribut~d over the outer surface
; th~reof and pro j~cting radially therefrom. Only a f~w of the
: total number of pellets found on a roller are shown in the
drawinys. The roller may also be hardened or may have a hard
i surface.
~: A roller shaft 50 having a~ axial bore 52 is also provided,
the outer diameter of the shaft being slightly less than the dia-
. meter of bore 47 so that the roller may be rotatably mounted on
;' the shaft. The roller also has a longitudinally extending flat 54
milled into the outer surface thereof~ the length of the flat
being slightly less than the length of bore 46. A cross bore 56
`:` is radially directed through the wall of the shaf~ betw~en the
',~`.J flat 54 and the bore S2.
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A pair of wear spacers 48, generally cylindrical in form
, axe rotatably mounted on the ends of shaft 52 via axial bore 60,
`; the spacers having the same diameter as roller 44.
'' ! A pair of mounting blocks 62 are also provided, one for
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~ each end of shaft 50. Each block has an upper curved surface 64
.$ having the same radius of curvature as main body 16. The other
;i 20 outer surface 66 of each block forms the arc of a circle and sub-
~ tends an angle of about 180. The radius of this arc is greater
.~ than the maximllm radius of roller 44 (including ~ellets a8) bu~
~ is less than half ~he width of opening 26 in the main body 16.
.. : Each block 62 is also provided with a stepped axial bore, the
diameter~of the bore 68 at one face being slightly less than the
diameter of shaft 50 and the diameter of the bore 70 at the other
~ face being less than that of bore portion 68.
il ~ Fi.nally, a tray or shield memkar 72 is provided, formed
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.J of sheet metal. The tray member is arcuate in cross-section with
~'`3A~ ~ 30~ - its inside surface having the same radius of curvature as surface
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:~` 66 on the bearing blocks.
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The rollcr asscn~)ly 18 is construct~ as follows. ShaEt sn is
inserted in ore 46 of th~ roller m~mb~r 44 and the wear spacers 58 are
unted to the s~ft, one a~jacent each end of the roller, The shaft is then
press fit in~o the bore 68 o~ each ~ountLng block, one mountmg block at
each end thereof. Care should be taken so that the flat 56 is oriented
relative to mounting blocks 62 such that the flat is not at the point of
greatest loading during opera~ion. This is seen in Figure 3, assuming
clockwise rotation. The tray member 72 is then positioned as in Figure 5
and is welded to the tw~ ~Dunting blocks as at 74. Thus the lower portion
(Figure 5) of the roller is protected by the tray member ~rom any dirt and
debris which might otherwise impinge on the roller in the vicinity of that
lcwer portion, the tray ~Ember thus exposing a longitudinal portion of the outer
surface of the roller me~ber 44.
Turning no~ to Figure 3 we see the overall construction of a stabi-
lizer, sh~wn in cross-section. Each roller assembly 18 is illustra~ed as
keing positioned in a respective opening 26 in main body 16 such that the
maxImum outside diameter of each tray has an interference fit with the sides
of its opening 26 and each tray ccmes into contact with the other trays
p~sitioned in the stabilizer. From Figures 1 aNd 3 it is seen th~t each
m~unting block 62 ~nl.l also be positioned within opening 26 whereby it may
be welded to the main body 16 along the adjacent edges of the unting blocks
62 and opening 2~ as a~ 76. Since th~ mountins block surface 64 has ~he s~e
radius of curvature as the ou~er surface of main body 16 the main body 16
wlll have an essentially continuous outer surface in ~'he region of the mounting
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`, blocks. Needless to say, a roller aase~bly, if w~rn or defective may be re-
i ~ moved from the ma m body as by air arcing and replaced with a new assembly. This
~ task may be easily performed in a mine maintenance shop an~ requires no special
~ equipment. Replaceable rollers means a greatly extended wear life as stabilizers
~ are frequently rebuildable three or four times. Replacement is greatly
~J` ~ faci~itated by having the three tray mmbers contact each other as seen in
Figure 3. If the roller assemblies are replacc~ one at a ~ime, the two roller
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~sS~mblies r~ ininc3 irl the st~bili~er provide location references for
the third roll~r ass~mbly b~ing replaced. This ensures concentricity
- between the working cent~r of the replac~nt rollers and the oriyinal aYis
of the stabilizer at the time of m~nuacture.
Figure 3 also illustrates the passages through which drill fluid
such as air will pass. First of all the majorit~ of the air will pass along
the main ~ore 20 in main bcdy 16. The air flowing in thiS bore will flow
:~ to the bit and is prevented from gaim ng access to the rollers by ~le tray
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;~ members 72. The tray r~bers 72 along with the weld between each mo~nting
block and the main body will also prevent leakage of air from the stabilizer.
~ A 5mall portion of the air flowing in the drill string will be:
en~rapped in the bore 52 in each shaft 50 and will flow therealong, the air
;~ entering the shaft via bore 70 in the upstream mounting block 62 and leaving
via bore 70 in the downstream bearing block 62. A small por~ion of this
kypass air Will flow through cross~bore 56 t~ the zone defined by flat 54
;~ and bore 46 to lubricate the r,oller 44 as it rotates on the shaft 50.
~ Finally Figure 3 shows that the use of a roller assemhly such as
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that shown in Figures 4 and 5 permits the designer to ~axImize the roller
diameter without sacrificing air flcW through the stabili2er. This is
0 achieved through use of the txay me~ber which protects the rollex, aids in
; preventLng air leakage~from bore 20 and permits the use of a main body
having a large diameter through-bore whereby the flow cxoss-section is still
,i; sufficient for proper air fl~w even with the roller assemblies 18 intruding
,' int~ the ~ore 20.
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In 5umm3ry therefore the present invention provides a stabilizer
in whi~h the roller diameter is maximized without
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dec/~ ~ -8-
54crificlng alr flow; the roller assemblies are ea~ily replaceable
ln the fleld to accommodate wear, defects or other problems, and
the stabilizer body ltself is repairable to accomodate wear or
other problems that might arise. The stabilizer of the present
invention, being repairable, will be less expensive to operate
and maintain in the field and will have a greater overall effec-
tive working llfe than prior art stabllizers~
It is evident tha~ variations in the basic invention
described herein are possible and may occur to someone skilled
in the art for example, it might be possible to construct the
mounting blocks 62 so that ~he wear spacers 58 are not required.
Accordingly the scope of protection to be afforded by the present
invention should be determined only from the appended claims.
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