Note: Descriptions are shown in the official language in which they were submitted.
~S~77
This a?plication relates to a tubing bit opener and, in
particular, to such a device adapted for the installation of
caissons in eart:~ formationsO
In applicant's Canadian Patent ~o~ 6~7,133, issued
July 23, 1963, there is disclosed a drill employing impact
cutters which ir one position extend beyond the diameter of the
drill body but in another position can be retracted so that the
drill can be removed through a caisson in position in the hole
which has been drilledO
The present application relates to an improved device
of the same type but one which uses rotary cutters and which has
advantages of easy disassembly for a maintenance and repair.
Specifically the invention relates a tubing bit opener
comprising a drill body having upper and lower rotary cutter
assemblies. ~he upper rotary cutter assembly consists of
pivotable arms supporting rotary cutters capable of being urged
outwardly ~rom the drill body under the control of a slidable
piston actuated by drill fluid pressure. The lo~er rotary cutter
assembly consists of mounting bloc~s each having a bevelled edge
therearound receivable in a matching undercu-t groove in the drill
body and supporting rotary cutters.
In its method aspect the invention relates to a method
oE positioning a calsson in earch formations uslng this tubing bit
opener, The method comprises the steps of arranging the caisson
to follow t~e tubing bit opener downwardly to the desired caisson
depth with the lower end of the caisson ad~acent a shoulder on
each pivotable arrn retracting the pivotable arms and removing
the tubing bit opene~ to leave the caisson in place,
-- 1 --
2~7
A preferred embodiment of the invention will now be
described with reference to the accompanying drawings in which:
Figure 1 is a cross-section of the tubing bit opener
sho~ing its operation in positioning a caisson in an earth
formation; and
Figure 2 is a fragmentary view showing additional
details of the upper and lower cutters.
6Z7~
Description of the Preferred Embodiment
Figure 1 shows a generally cylindrical drill body,
indicated at 10, having a threaded connection 11 in its upper
portion arranged to receive a conventional drill rod connector
120 Drill ~ody 10 is provided with two sets of rolling cutters,
The upper cutters 13 are received in a recess 14 and carried by
an arm 16 pivotally mounted at 15 so that they can be extended
outwardly of the bodyO The lower cutters 20, which are readily
replaceable~ are securely fastened at the lower end of the drill
body at a position to remove material to form a hole of the
appropriate diameter to receive the drill body.
A cen~ral passage in the drill body communicates with
the drill pipe through passage 21 in connector 12 to receive the
stream of air or water used as drilling fluido This central
passage leads to side passages 22 communicating with the upper
set of cutters 13 and lower passages 23 communicating with lower
cutters 20 so that debris released by the cutters may be swept
away~ Longitudinal grooves are formed along drill body 10 at
positions not occupied by`the cutters to provide a passa~e for
return to the surface of material di.slodged~
A movable piston 24 is located in the central passage
and is used to control the expandable movement of the arms carrying
the cutters. ~iston 24 has passages 25 formed in it to permit
the drilling fluid to pass downwardly through the central passage
in the drill body when the piston is displaced downwardly~ When
the pressure of drilling fluid in the drill pipe increases it
acts on head 2~ of piston 24 to force it downwardly against the
12~l~2~
force of spring 27. The side wall of piston 24 bears against
a pin 30 mounted for sliding movement in the drill body,
Outward movement of pin 30 forces the arms carryin~ cutters 13
outwardly by pivotal movement about pin 15,
On reduction of drilling fluid pressure piston 2~
moves upwardly under the force of spring 27 permitting pin 30
to move inwardly, This in turn, permits cutters 13 to move
into the recesses 14 under the force a~plied to arms 16 by
sprinqs 31 located above the pivot pinO
Additional details of the structure of the cutters may
be seen in Fi~ures 1 and 2o The lower cutter mountinq bloc~ 20
is formed with a bevelled edqe 40 extendinq therearoundO This
edqe is received in a matchinq undercut qroove 41 formed in the
lower portion or the drill bod~, The mountinq block is held
ri~idly in Position by bolts ~l3 but, as can be seen. can be
readilv dismounted from the drill bodv for rePlacement of the
cutterO The cuttinq elements are formed bv carbide tiPs 45
but could instead be formed bv toothed steel, if desiredO Upper
cutters 13 are each provided with a ~rease Passaqe 32 communicatina
with roller su~Port bearinqs 33~ Similarl~, lower cutters 20 have
a ~rease Passaqe 34 communicatinq with roller suPport bearinqs 360
Bv weldin~ or solderin~ the ends of the axle containina the ~rease
supply tube to the cutter mounting block, as shown at 35 a par-
ticularly rigid structure is obtainedO The axle containing grease
tube 32 of the upper cutter can similarly be welded or soldered
to the arm to provide a rigid axis about which the cutter head
rotates,
~2~l627~
A typical use of the tubing bit opener of this invention
is to sin~ a caisson as shown at 50 in Figure lo As the tubing
bit opener moves downwardly into the ground caisson 50 follows
closely behind shoulder 51 provided in the expandable cutters 13.
This provides two advantages: the first is that the caisson acts as
a guide to provide good alignment of the hole being drilled; the
second is that the caisson prevents debris from the hole falling
inO Once the arms carrying cutters 13 have been retracted, the
drill can be withdrawn through the caisson leaving it in its
final positionO
The drill body, the expandable cutter arms and the
replaceable lower cutter units are formed from precision cut
steel~ Since che cutter arms and the lower cutter units are
interchangeable among themselves, fewer spares need be kept,
Typical dimensions are a drill body of 6 inch diameter with the
expandable cutters extensible by 9116 inchO The caisson used
can have a wall thic~ness of 3/16 inch and an inner diameter of
6 3/16 inch, When followin~ the tubing bit opener downwardly
the end of the caisson is spa~ced by about 1/2 inch from shoulder
Sl~ I~ the formation proves to be unconsolidated, then cement
can be pumped down the drill rod to flow outside the caisson and
to the formation. The tubing bit opener can be gradually with-
drawn during this process~ After the cement has hardened drill-ing
- can be resumed through the now stabil-ized formation~
