Note: Descriptions are shown in the official language in which they were submitted.
108Z68S
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BACKGROUND OF TEIE INVENTION
The present invention relates to a rotary drilling bit for well drilling:.
and more particularly is related to a new tool to be used with the rotatory -
drilling method, which presents remarkable differences and advantages over
the conventional drilling tools and drills heretofore used.
To provide an idea about the differences and advantages of this new --
tool, it is considered necessary to describe briefly the drilling bits of the
rotatory type which exist in the market. . I
At present the bits are separated In two big groups, the flrst one - - ~ .
iC: comprising all of those bits which do not have any movable part, which are -
made from one piece and rotate in an integral form~. This type predomin~ntly
scrap or drag the bottom of the well such as the so called "flsh tail" bits, - ,.. ~
wing bits, and diamond bits. With these types the drilling is performed by - ~
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108~85 2.
the rotation and by the application of a determinate weight on the bit such a -
manner that the bottom of the well is scraped, and the detritus are drawn into
the surface by the circulation of the drilling fluid. These bits are very rarely
used at present time, except in very special instances due to the limitations
thereof, specially with regard to the drilling of hard formations, principally
massive rocks.
The second group relates to bits which havè rotating or rollirig elements
in their lower part; these rolling elements are principally cones with strias -
or teeth which roll in the bottom of the well by the application of the weight on
1~) th~ bit, the rolling resulting in the crushing of the rock. The crushed formation
is drawn into the surface by the circulation of the drilling fluid. The rolling - `
elements in the actual bits always are in a variable number, the more ordinary
being those which comprise three cones integrated in only one piece and which
can not be disassembled or taken apart and therefore can not be repaired. In
fact the triconical bits are built by manufacturing separately each one of the -
three cones and its corresponding leg provided with bearings and seals which
are individually built, that is each one of the legs is separately built. Then -
during the manufacturing these three parts are bond by welding, forming a --
single unit. The bit undergoes a wearing of the teeth of the cones, of the cones
themselves, of the seals and of the bearings, and thus after of a certain time,
when the failure or the wear of some of these constructive elements occurs,-
the bit will be totally useless, without the possibility of repairing, th0 result
is a large waste of material and work which never can be recuperated. Once
some of its elements fail the bit is totally discarded without the possibility of
recuperation. Another variation of this ty~e of bit is the so called cross bit
which comprises four tooth rollers, ¢ones or rolls arranged in a such manner
that two of the rollers are placed along one of the diameter~, but without - o
totally cutting th~ full diameter, only the central part, and the o~her two - -
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~3268S 3- ~
rollers are placed at 90 and cut the circumferential part of the well to be --
drilled. Sometimes these tools were able to be repaired but with a considera
ble cost, and its efficiency is limited, thus it is very rarely used.
There is another~ group of drilling bits, known as differential or - -
Zublin bits. These bits are of the single cutting head type, reparable and --
replaceable, which are up to now practically obsolete because of their poor -
efficiency and limited use. In fact these bits perform like drag bits because
the motion of the cutting heads is rather a wobbling motion instead of a true
rolling mechanism. The Zublin simplex bit which has an almost spherical -
cutting head rotat ing in an inclined angle of 30 degrees from the vertical -
produces a scraping and reaming action in an up and down motion combined -
with some rotation.
SUMMARY OF THE INVENTION
The characteristics of this new invention consist in that instead of -
being provided with several cutting rollers or cones, it is built in a such - -
manner that a single cutting head is ùsed, but with a true and perfect rolling
motion against the bottom of the hole with a crushing milling and grinding -
action thereby enabling it to drill through any kind of formation including very
hard roeks. Besides, this cutting head can be easily dismounted from the
body of the bit in order to change the constructive elements, such as seals,-
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bearings and the cutter itself, so that the bit body which involves a eonsiderableamount of material and work, can be used practically in an indefinite form, -
simply changing the constructive elements above mentioned such as the cutting
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10826~3S
head, bearings and seals. Also dif~eren~ cutting heads with
different characteristics can be used to drill appropriately
formations with different hardness and characteristics.
Thus the present invention provides a rotary drill for
drilling a well in the surface of the earth, said drill comprising:
(a) a drill bit including an upper portion for connection
to a drill string, duct means including a fluid outlet into the
well for carrying fluid to extract detritus and clean the bottom
of the well, and means for receiving and retaining a solid cutting
head within the drill bit;
(b) said solid cu~ting head comprising a conical head por-
tion and a unitar~ stem portion with no internal passages therein,
said conical head portion including holes therein and cutting
elements inserted in said holes, said stem portion being received
in said drill bit, wherein said stem portion and said drill bit
comprise the retaining means for rotatably holding said cutting
head in said drill bit;
~ c) sealed, lubricated bearing means between said drill
bit and said conical head portion, said bearing means being fixed
relative to said drill bit and to said conical head portion for
preventin~ movement between bearing surfaces of the bearing means
which c~ontact the drill bit and the conical head portion, but
allowing said conical head portion to rotate relative to said
drill bit; said bearing means being independent of said duct means;
and
(d) stabilizer means for equalizing the pressure in the
bearin~ means with the pressure in a bore hole surrounding the
drill bit.
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Therefore, th~s ne~ tool involves a considerable advance
in the decreasing of the drilling costs, since it i9 a tool
which can ~e used practIcally
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~08Z~;85 4
in an indefinite form, changing the constructive elements as the wear is
observed, with ~t being possible to change the rolling devices hereinafter
described, and to change of the cutting head itself using the same body, -
which in case of necessity can be repaired, readjusted and reused.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the performing and building of the
new tool, attached are drawings in which:
Figure 1 is a side view of the present invention.
Figure 2 is a sectional side view showing the present invention.
Figure 3 is a sectional view of the drill bit body of the present -
invention .
Figure 4a is a bottom view of the cutting head of the present - -
invention .
Figure 4b and 4c are sectional views of the cutting head of the -
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 represents a side view of the full piece.
The drill bit body represented with number 1, is a single piece and its - -
inner construction will be shown in the following figures. The piece number
~0 2 represents the cutting head formed by a cone with certain characteristics-
that will be described hereinafter, and which penetration or cutting elements
of the ~ormation are comprised by teeth represellted by the number 3.
The tungsten carbide beads representecl with the number 4, are - -
necessary parts whrch avoid the cutting head loss material decreasing its -
diameter as a result of the friction against the well walls. The portion - -
designed in number 5, represents a square or plane on both sides of the bit
body in order to allow its twist through a special key to th~ rest of the - -
drilling column to which it is fas~ened by the conical threads number 6.
In the figure 2 is illustrated a cross section o~ the entire tool ~nd -
1~2685
its components parts. The cutting head 2 is formed by a cone which has a very
wide vertex, forming an angle represented with the letter A. In the particular
case of the drawing, this angle A is 155, but of course it can vary according
to the design and with the drilling of the distinct formations. This cone also
hElS a stem or large shaft illustrated with the number 7 in a such manner that
the axis of this cone and its stem represented by the lettersF-F, makes an -
angle with the tools axis represented with the letters E-E. This angle is - -
sho~vn in the drawing with the letter D, and this angle is equal to that formed
by the plane of the cone and the horizontal line of the well bottom illustrated -
la with the letter C,
The working of the tool is as follows: upon the rotation of the bit body~onnect~d to the drilling column 1, acting through the bearing devices and the
shaft of the cutting head or cone 2 to carry out its rolling in the well bottom
on generatrixes o~ this wide cone, in a successive form in a such manner that
upon completion of a turn of the body 1, the cone will have carried out its - -
rolling, resting successively its generatrix on the bottom of the well completing
a little more of a turn since the diarneter of the cone is slightly less than the
diameter of the hole. In this manner is possible to observe that there is not -
a scraping or sliding effect between the cone and the well bottom although a -
~a perfect rolling is produced since both the cone axis and the body axis just - -
coincide in the cone verte~, Obviously this arrangement which is illustrated -
in the drawing can be modified forcing a slight displacement of the cone axis '~
into any side, in a manner such that in addition to the rolling, a sliding is - -
produced and, therefore, the drilling is produced both by crush~ng through a- '
true rolling and by a sliding or scraping of the bottom of the well it being - -
possible modify the design to produce the desired effects.
It can be observed that the cone and its stem or shaft is locked in - -
place through tne steel balls device represented with the number 8. This device
really forms a hold means or a rotar~ lock which is obtained by means of a --
A
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slot with an semi-circular groove in the stem and an~Lher semi-circular -
groove in the bit body taking into account the necessary mechanical lolerances.
The steel balls or bullets are introduced through the orifice shown, and -
then it is closed or sealed by means o~ a screw 13 and the check nl~t 14 so
that by means of this arrangement the bullets can be withdrawn, and the -
cone and the other bearings which will be described hereinafter can be - -
withdrawn ~or change, readjustment or repair, according to the drilling -
necessities .
The loads which act on the mechanism by the drilling action will-
be absorbed or transmitted by means of the roller bearings 9 and 10. Roller
bearing 9 absorbs the excentric stresses or moments, or the radial loads,
and thrust bearing 10 absorbs the loads and the stress which are axially -
produced in the action line of the cone axis and its stem ilustrated in the -
dra~ving with the FF line.
Th~se
Thi~ roller bearings both radial and axial that is 9 and 10 respec
tively remain assembled and adjusted by means of the thick washer or - -
~lange ll, which transmits at same time the axial forces to the thrust - -
roller bearing lO and adjust the exact position o~ the roller 9 to fasten it
against the upper face of the work cone 2.
It should be noted that the arrangement of these roller bearings -
can be changed in order to accommodate like roller or ball bearings from
several manufacturers of thesè mechanisms and it also should be noted --
tllat in lieu of these roller bearings of the roll type, journal bearings (rriction
or ~luid film bearings) can be used without changing the basic performance
o~ this tool. This mechanical arrangement is always lubricated, and the --
lubricant is contained within the internal mechanism spaces retained by the
double annular seal 12 wherein a slipping o~ the flat race against the body -
is produced, resting exactly on the seals 12 avoiding that the grease leaks
to the exterior. At the same time the drilling fluid with the sandy detritus
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~C~82685 7'
o~ the crushed material is prevented from penetrating and damaging the -
internal lubricated mechanism.
The lubricant necessary ~or the mechanism is supplied through the
duct 15 and the duct 17 by means of the grease cup 16 so that all the spaces
o~ the mechanism are filled with the proper lubricant.
The device 18 represents a very useful fitting which is not the - -
subject of this patent and properly is a diaphragm through which the stabi-
lization of the internal pressure of the lubricant is obtained. The changes
of external pressure when the bit is introduced into the hole or is withdrawn
therefrom are balanced by means o~ this diaphragm and the pressure that -
th~ drilling fluid exérts in the interstice 25 such as on equalizing both in the
points 25 and 24, the lubricant can not be exhausted and the drilling fluid -
can not go into the internal mechanisms of the bit. For the disposal of the
detritus from the formation or the cuttings produced by the teeth the nozzle
19 is used which is formed by a tungsten carbide piece fastened to the drill
bit body by means of the nut 20 which seals against the drill bit body through
the gasket 21. The drilling ~luid is transmited through the drill string by -
the duct 23 and the duct 22 of the nozzle, which at high pressure exhausts-
a jet between the hole wall and the raised part of the cone No. 2 with said
~n wall producing the necessary turbulence to withdraw the detritus and clean
the well bottom so as the cone teeth of the cutting head always impinge on
the clean formation.,
Figure 3 is a longitudinal section view of the external parts wherein
the cutting head is eliminated and is shown with great detail the housing 29
for said cutting head 2. Likewise in the middle portion of the upper region
of said housing 29, is illustrated the external surface of the channel 26 ~
wherein are housed the rolling balls with the access hole closed by the --
nut 13 and check nut 14.
Although in this ~igure the greased cup head 16 is not illustrated,
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the lubricator ducts 15 and 17 are shc>wn with duct 17 c~?ntacting the housing
29 for the head, and the diaphragm pressure stabilizer 30.
In the upper central portion of the bit body is large duct 23 which -
communicates laterally with the duct 22 in the bottom portion of which is the
nut 20 and the ~asket 21.
;i3Figure~shows the cutting head 2 but the tungsten carbide inserts
are not illustrated, being represented only the holes or perforations 31 in
which this tungsten carbide teeth will be placed. The arrangement of these
inserts can be variable of course in spacing, position etc. Thus it will be
la possible to conform the end of the bit for drilling of several types of forma
tions. The emerged portion of the teeth could be larger or shorter, also its
spaci~g in a different forrn according to the requirements of the drilling of
the several formations such as the drilling of sand, granite or clay. Of course, L
the free elements described in the manufacture of this drill, allow the making
of all of the variations necessary for the better working o~ the piece, according
with the formations to be drilled, and therefore the advantage which comprises
the ability to change several cutting heads with different teeth arrangements
to obtain precissely the end intended, without the necessity of changing the -
entire bit as is the case in the prior art.
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