Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02294409 2000-O1-07 -
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CORE ORIENTATION
FIELD pF THE INVENTION
This invention relates to core drilling and more particularly to apparatus
and methods for determining the original orientation of a core sample after it
has been drilled, separated and pulled out of the earth.
BACKGROUND ART
Many forms of geological survey depend on core drilling for samples.
Some surveying requires that the orientation of a core be determined
accurately and reliably. In many situations the angle of the longitudinal axis
of
the core drill relative to the "plane" of the earth at the drill site is other
than 90
degrees. This is the drilling angle and it may be ascertained in a number of
ways. It is sometimes also important to determine, after removing the core for
inspection, the rotational orientation or compass orientation of the core
sample
relative to the surrounding terrain from which it was extracted. Known prior
methods are not reliable.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an apparatus for use with core
drilling devices which includes a hard ball which runs in a circumferential
track.
The ball and track are adapted to be carried within a tubular upper end
casing,
which surrounds the spindle which supports the inner tube of the drill. An
indent washer is positionable above the track and ball and is oriented
relative
to the casing. A spring supports the washer above the ball. When the upper
end is lifted, the ball is driven into contact with the washer and makes an
impression. The orientation of the impression reveals the orientation of the
lowest point in the trade. The impressioned washer can be used to assist in
noting or marking the core orientation after the drill is removed from the
earth.
In one preferred embodiment of the invention, the washer is formed with
an alignment hole. The upper end casing supports a pin which extends in the
direction of the drill rotational axis. The pin passes through the hole to
maintain the washer in a fixed alignment with the casing. ~--
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In another embodiment of the invention the spindle is split into upper
and lower segments, the lower segment having a flange which bears on thrust
bearings.
In another embodiment of the invention, a laser pointer system is used
to transfer orientation information to a core which has been driNed In
conJunetlon with a ball, track and waslm device as disclosed with rcfercnce to
the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross section of an upper end of a core drill inner tube;
Fig. 2 is a cross section of the track;
Fig. 3 is a perspective view of the indent washer;
Fig. 4 is a cross section of the casing of the upper end; and
Fig. 5 is a perspective view of an inner tube and upper end, showing
the use of the levels and indent washer in marking the core;
Fig. 6 is a crass section of another embodiment of the invention;
Fig. 7 is an enlarged view of the coupling portion of the embodiment
shown in Fig. 6;
Fig. 8 is an exploded perspective view showing the halt, track and
indent washer;
Fig. 9 is a front elevation showing an alignable laser stand and clamp;
Fig. 10 is a side view of the device depicted in Fig. 9. A laser pointer
is held by the device;
Fig. 11 is a laser mask or image intensifier which is used in
combination with a laser pointer according to the teachings . .
of the lnventton;
Fig. 12 illustrates a front elevation and a cross-section of a disc reader;
Fig. 13 illustrates a front elevation and a side elevation of a cure
reader;
Fig. 14 illustrates laser assisted marking of a core sample.
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A care drill usually comprises and outer tube and an inner tube. The
outer tube is rotated and transmits rotational power to a cutting head. A
drill bit
on the cutting head forms a core which rises up through the inner tube as the
drill progresses into the earth or substrate. The inner tube and separated
core
may be lifted up through the outer tube by lowering a latching body through
the
outer tube and latching onto a spindle carried by the upper end of the ir~rrer
tube. The latching body is lowered on a steel cable and engages the upper
end of the spindle. Tension on the rod string is translated, by a core lifter
within the drill, into a compressive force which acts to fracture the core and
separate it from the substrate. The separated core can then be lifted, within
the inner tube, by the cable attached to the upper end.
The present invention has been devised to create a valuable and
accurate record of the compass orientation of the core at the moment of
separation.
As shown in Figure 1, an upper end 10 includes a spindle 11 a casing
12 and a shield 13. Threads 14 at the lower end of the shield engage the
upper threads of the inner tube of the core drill. The spindle 11 passes
through
the plug 15 which caps the top of the casing 12. A compression spring 16 is
trapped between the plug 15 and a nut 17 which is threaded on to the spindle
11 and secured thereto by pin 18. The lower end of the spindle 11 passes
through a bronze bushing 19 and terminates in a threaded stub 20.
When the rod string is raised, the spindle 11 is placed into tension. As
shown in Figs. 1 and 8, this causes a nut 21 threaded onto the stub 20, to
bear
against a washer 22 and consequently onto a track 23. The track 23 . .
surrounds the spindle 11 and faces upwardly or away from the threads 14. A
groove 24 is formed in an upper face of the track. The groove 24, when the
track is installed, also surrounds the spindle 11. An indent washer 25 is
positioned between the track 23 and the Power end of the casing 12. A non-
magnetic steel or other non-metallic hard ball 30 rolls freely in the groove.
The
diameter of the ball is slightly larger than the depth of the groove 24. In
all w-
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non-vertical drilling, the track 23 is tilted. When the track is tilted, as in
the _ ,
case of non-vertical drilling, the ball rolls to the lowest point in the plane
of the
groove 24. The trade 23 is shown in Figure 2.
Until the track 23 is brought into the proximity of the Ivwer end of the
casing, the indent washer 25 and the track 23 are kept apart by a spring 26.
The spring keeps ll m indent washer 2~ in contact with the lower end of the
casing 'I2. The indent washer 25 (shown in Figure 3) is formed from a
relatively soft metal such as copper or brass that can be impressed or
indented
with a steel ball. The indent washer has a central opening for receiving the
1 D spindle '! 1 and an alignment hole or pilot 29.
As shown in Figure 4, the tower end of the casing is fitted with a pin 27.
The pin 27 extends in the direction of the drilling axis 28 and extends into
the
pilot or hole 29 formed in the indent washer 25. This keeps the rotational or
compass orientation of the indent washer 25 indexed or fixed, relative to the
casing 12. The pin 27 does not interfere with the rolling of the ball in the
g roove.
When a core is being separated by raising the rod string, the spring 26
compresses as the track 23 is brought toward the indent washer 27. Before
contact, the ball 30 has rolled to the lowest point in the groove 23.
Eventually,
the ball becomes trapped between the track 23 and the indent washer 25.
Further tension in the rod string causes the ball 30 to be driven into the
surface
of the indent washer 25. This action makes an impression or indent in the
washer 25 and the indent is known to be formed at the time the core is
separated. When the drill is other than absolutely vertical, the angular (or
"compass") position of the impression marks the bottom or lowest (vertical)
point in the groove 24 and therefore in the plane of the washer 25. Both the
groove 24 and the washer 25 are perpendicular to the long axis of the drill.
Because the indent washer 25 is pinned to the casing, its orientation
relative to the casing is known. Thus, the impression can later be related to
a
CA 02294409 2000-O1-07
reference mark or groove 31 formed on the outer surface of the casing. This is
_
shown in Figure 5.
Figure 5 show how the core's orientation is determined. In this example,
the pin 27 and reference groove or mark 31 are aligned during the manufacture
5 of the casing 12. To be exact, the reference mark defines a plane through
the
drill axis Z~. Nreferably and conveniently, the pln Is formed in this plane
(on
the same side of the centreline 28 as the mark 31). The pin and reference mark
31 need not be in the same plane so long as the angular relationship of the
two
different planes is known. This relationship allows the location of the
alignment
hole 29 in the indent washer 25 to be related to the location of the reference
mark 31.
This means that the indent washer 25 can be removed after drilling and
the indent washer 25 can be used to mark the bottom or low point of the core.
This is done by laying the re-assembled top end 10 and inner tube 40
horizontally and rotating them together until the reference mark 31 faces
straight up. To do this, a specially adapted level 41 is used.
The level is in the form of a saddle 44 which conforms to the
circumference of the upper end 10. The level includes a ce~trai reference
mark 42. A spirit level or other levelling device 45 attached to the saddle
indicates when the reference mark 42 is at its vertical maximum. When the
reference mark 42 is at its maximum and also aligned with the reference mark
31 on the casing 12, the reference mark 31 is known to be in a vertical plane
which passes through the drill axis 28. Next, the same or a second level 43 is
used to note the vertical maximum of the lower end of the inner tube 40 and
therefore of the core sample within. By aligning the hole 29 of the indent
washer 25 with the indicated vertical maximum of the lower end of the inner
tube 40, the impression 32 can be used to indicate where to mark an index
point onto the core.
The index point indicates the location of the "bottom" of an inclined slice
of the core sample. It should be apparent that an imaginary line which passes
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radially from the drill axis 28 through the index paint defines the compass
_.,.,.
orientation of the core_ This is because the inclination of the drill axis in
the
earth can be related to a compass direction. This may be done befare, during
or after drilling by observing the compass orientation of the vertical plane
which
contains the drill axis 28 at the cutting head at the time when the core is
separated.
In order to minimise wear on the bushing 19 an alternate embodiment of
the invention is contemplated. As shown in Fig. 6, the spindle 110 is split so
that the lower portion 111 of the spindle rotates independently of the upper
portion 192 of the spindle. Tension is transmitted from the upper portion 112
to
the lower portion 111 by a coupling 113. The coupling 113 is at one end
threaded to a lock nut 114 and serves to restrain the lower portion of the
spindle 111 between a pair of thrust bearings 115, 116_ The lock nut 114 is
threaded unto the bottom end of the upper spindle 12 and has a threaded
exterior to engage the coupling 113.
The lower portion of the spindle 111 carries an integral flange 117 which
is trapped by the coupling but which rotates freely within it. Ball bearings
118
support the lower portion 111 within the coupling 113. The coupling
arrangement allows the tower portion 111 to rotate independently of the upper
portion 112. This arrangement minimises the rotation of the lower portion '111
and minimises wear on the seals 120, preferably two in number, which seals
prevent grease, water and mud from interFering with the operation of the
track,
ball and washer arrangement 125.
In order that orientation information can be more efficiently transferred to
the core sample, an optional laser pointer system is provided (see Figures 9-
14). As shown in Figure 9, the laser pointer system includes a laser mount
200. The mount 200 includes a tube clamp 201. The inside diameter 202 of
the tube clamp 201 is adapted to encircle an outer circumference of an outer
tube 203 (see Fig. 10). The clamp 201 also includes an exterior hinge 203 and
a tensionable fastener 204. When the fastener 204 is loosened, it may swing
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out of position (see arrow) 205 for facilitating installation and removal from
the _._._
tube 203. The inside diameter 202 of the clamp 201 also includes a key 206
which is adapted to ft into the alignment groove 207 which is formed on the
exterior of the tube 203. The laser mount 200 further includes a pedestal 208
which extends from the clamp 201 to an adjustable pivoting laser retainer 209.
The retainer 209 is affixed to the pedestal 208 and allows for vertical only
adjustment of the beam produced by the laser pointer 210. The pointer 210 is
held by a second clamp 211 which is adapted to allow easy insertion and
removal of the pointer 210.
The laser pointer system may be utilised once a care drilling operation
has been completed, and the core has been broken and removed from the drill
hole. The tube is removed as usual and placed on a horizontal rack. The tube
203 is placed on the rack in a position where the groove 207 in the back end
is
facing up. The Laser mount 200 is then positioned over the groove with the key
206 located in the groove 207. The mount is then locked in place with the _
fastener 204. The Laser beam is adjusted in the vertical plane owing to the
adjustability of the retainer 209. The laser is manipulated until the dot of
light
produced by the laser (usually red) impinges on the core or the end of the
cure
lifter case as required. The fasteners 212 on the retainer are then tightened
thereby securing the laser pointer in position.
Next, an image intensifier or mask 215 as illustrated in Fig. 11 is slid
over the lifter case and lined up with the centre of the laser dot. Because
the
slot 216 in the V-shaped mask 217 is narrower than the diameter of the laser
dot, a thin line of laser Ilght wilt appear on the core or core lifter case.
The
laser tight exiting the image intensifier 215 corresponds with the location of
the
index groove 207 and with the hole 29 in the indent washer 25 (so long as the
relationship between the index groove 207 and pin 27 is known). Using a
sharp pencil a thin mark is placed on the care where indicated by the line of
laser light as shown in Figure 14.
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Next, the core is removed from the tube and placed on a tray or marking "._
rack. Then, the indent washer is removed from the drilling apparatus. A
measurement is then made of the angle between the washer's alignment hole
29 and the indent mark (for example 32). This may be conveniently achieved
using a measuring device of the type illustrated in Fig. 12.
As shown In Fig. 12, the dlsc reader 220 preferably includes a
measurement ring 221 affixed to a diso-like base 222. The washer fits within
the central opening 223 of the ring 221 and may optionally be supported by the
base 222. When the hole 29 of the washer 25 is aligned with the hole 224 of
the reader 220, the angular displacement of the indent 32 can be read directly
from the measuring ring 221.
Next a core reader 230 (shown in Fig. 13) is placed over the end of the
core. The zero mark 231 is oriented with respect to the line or impression
made by using the laser pointer on the core. Using the measurement produced
by the disc reader 220 the angular displacement of the indentation can then be
marked or transferred directly onto the core using the measurement ring 232 of
the core reader 230. Note that the measuring ring 232 of the core reader 230
is affixed to a cylinder 233 whose inside diameter 234 is adapted to slide
over
the core.
It will be apparent that the invention has been described w(th reference
to certain details of construction and that these details should be
interpreted as
examples and not as limitations to the scope of the invention.
