Note: Descriptions are shown in the official language in which they were submitted.
1
The invention relates to the field of earth drilling
equipment, and more particularly, to an earth drilling apparatus
attached at an end of a vehicle-mounted boom, especially to permit
substantially vertical boring through hard earth, rock, or rock-
like material, at a distance from the vehicle.
The electric utility industry relies heavily on overhead power
lines to distribute electrical power to its various customers.
High voltage power lines emanating from a generating station are
strung between transmission towers. The high voltage power is
stepped down to a lower voltage via transformers at an electrical
substation, on utility poles, ar elsewhere. Power lines carrying
lower voltage power are strung between smaller utility poles and
lead eventually to individual residences and businesses. Utility
poles may support power lines, telephone lines, cable TV lines,
etc., and similar poles may be used as pilings or footings for
structures.
The utility pales typically are simply placed in the earth.
The poles have a portion of their length, typically 10 percent plus
2 feet, embedded in the earth, which typically is filled or peaked
around the pale. The pole protrudes upwardly to provide a location
for fixing cables and the like, or far attachment of structural
members. Holes must be drilled in the earth to accept the embedded
portion whenever a new or~replacement utility pole is to be
installed, and pole installation and maintenance are frequent and
routine jobs for utility companies and the like. The standard pole
hole must be in the range of 6 to 10 feet deep to accommodate a
standard utility pale up to 17 inches in diameter at its widest
part, and typical7ly anywhere from 20 to 50 feet high.
The utility poles are commonly located at regularly spaced
locations along the side of a roadway. The terrain along the side
of the roadway may be flat or sloped, smooth or jagged. The earth
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itself may include sand, dirt, clay, broken or solid rock, or any
combination of these. Often, the side of the roadway terminates
in a steeply ascending or descending rock-faced cliff. Tt is
advisable to support the utility lines at a regular spacing to
avoid undue tension or an unduly low arc in the lines, and to avoid
installing an unnecessary number of poles. Therefore, the utility
industry has a need to drill pole holes in the earth regardless of
the character and condition of the earth at the respective
location.
Earth drilling bits and drives adapted for all types of
material are known. The utility industry generally employs auger
type drills for producing holes in loose material. The auger
apparatus is mounted on a vehicle and typically includes a
hydraulic motor and a helical auger bit which is rotated by
hydraulic fluid pressure generated by a hydraulic pump on the
vehicle. The auger apparatus may be mounted on a boom extending
from the vehicle, and the boom is generally rotatable over a
limited span to either side of the vehicle such that the auger can
be positioned for drilling a hole anywhere within a range
determined by maneuvering the vehicle and moving the boom to
position the auger at a distance from the vehicle. An auger bit
is not suitable for drilling through rock, broken rock or rocky
soil, as the rock will quickly wear out the auger bit. Further,
the auger apparatus is not suitable for drilling in steeply sloped
earth because the apparatus is not supported near the auger bit,
other than by the earth itself. Thus, the auger bit tends to slide
downhill whenever hole drilling in steeply sloped earth is
attempted.
Rock drill bits are also known. These bits may include, for
example, a drilling face having one or more hardened cutting
elements embedded in the face and protruding toward the rock to be
cut. A percussion tool, typically operated by compressed air, is
generally attachec't behind the rock drill bit for delivering
repetitive blows through the rock drill bit to the rock. The
percussion tool and the drill bit can be attached at the bottom of
a drill string, all or part of which is also rotatable about an
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axis by a drill head attached to the 'top of the drill string. Rock
drill bits are commonly used by water well drillers in conjunction
with vehicle mounted drilling equipment. Water wells may reach a
depth of several hundred feet or more, and the well drilling
vehicles include a relatively tall mast so that the drill head can
be raised to a height above the ground sufficient to enable long
lengths of drill pipe to be inserted or removed laterally into the
drill string beneath the drill head.
Water well drilling equipment is not suitable for drilling
utility pole holes, which xequire a quick setup and only a short
hole depth. Since the water wells extend much deeper 'than the
utility pole holes, water. well drilling equipment is necessarily
large and expensive and is setup relatively permanently as compared
to utility pole drilling needs. The tall mast may interfere with
trees along the side of the roadway. Of even greater concern, in
the case of hole drilling for replacement utility poles, is
potentially disastrous contact between the mast and existing power
lines. Further, the tall mast cannot be used as a practical matter
to conveniently place a drilling apparatus over a roadway guardrail
to drill a hole an the remote side thereof.
Rock drills also have been mounted on cranes, which likewise
have large booms . U. 8 . Patent No . 4 ,102 , 094 to MacKinnon discloses
a drill mast attached at an upper end to a large boom. An
adjustable brace extends betcaeen the boom and a lower part of the
mast to stabilize the mast and maintain correct alignment of the
mast above a hole being drilled. The mast disclosed by MacKinnon
is complex and bulky and does not overcome the practical
disadvantages of such apparatus with respect to the job of drilling
regularly spaced utility pole holes, such as excess mast height,
high cost and inconvenience.
Heretofore, attempts to employ a rock drill on a truck mounted
boom of the type normally used for auger drills have not been very
successful. The booms have free play in their joints and tend to
flex under the load of rock drilling. ~1s a result, the drill bit
tends to walk across a surface instead of digging in, and after the
hole is started the bit is easily deflected from drilling in a
straight line. This results in jamming of the bit in the hole,
broken bits, increased drilling time, improperly aligned holes,
etc. Consequently, the standard method of drilling utility pole
holes in rock is manual; that is, a man with a jackhammer breaks
up the rock and the rock is removed with a shovel. This method is
obviously time consuming, and a single hole may take a day or
longer to drill to the required depth. There is thus a need in the
utility industry for a drilling apparatus which will overcome these
problems.
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It is an object of the invention to provide an apparatus for
efficiently drilling utility pole holes, especially in broken or
solid rock.
Tt is another object of the invention to provide an earth
drilling apparatus which can be used in conjunction with
conventional utility pole hole drilling vehicles.
It is a further object of the .invention to provide an earth
drilling apparatus which attaches to a boom on a hole drilling
vehicle.
It is yet another object of the invention to provide an earth
drilling apparatus which interchangeably attaches to booms on
different vehicles.
It is still another object of the invention to provide a
convenient earth drilling apparatus which is more versatile than
commonly used earth drilling apparatus.
These and other objects are accomplished by an earth drilling
apparatus for use with a vehicle of a type which performs utility
pole hole drilling operations. The vehicle has an elongated
structure attached at one end to the vehicle, the other end being
maneuverable, and means for providing hydraulic fluid under
pressure to the apparatus through hydraulic fluid couplings. The
apparatus comprises an elongated guide means having means for
attachment to the elongated structure. A drill head is movably
mounted for advance and retraction along at least a portion of the
guide means. The drill head comprises at least one hydraulic motor
for producing operative movement of a body. Means are provided for
communicating the hydraulically produced forces from the vehicle
to the drill head. Furthex means axe provided for moving the drill
head along the at least a portion of the guide means. A drilling
tool is attachable to the drill head and is thereby oriented to
drill a hole as the drill head is moved with respect to a ground
surface. A stabilizer atvtached to a lower end of the guide means
defines anchoring holes for receiving pins which are driven into
the ground in order to fix the guide means against transverse and
rotative movement of the guide means. The invention thus provides
6
a quickly erected arid effective means to drill holes of a size and
at locations suitable, for example, for utility poles along the
sides of highways.
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In the accompanying drawings:
Fig. 1 is a perspective view of a drilling apparatus according
to the invention, the drilling apparatus being attached at an outer
end of a boom which is mounted on a vehicle.
Fig. 2 is a perspective view of the drilling apparatus before
attachment of a drill pipe and a drill bit.
Fig. 3 is a side view of the drilling apparatus with the drill
pipe and the drill bit, the drill head being shown in raised
(broken lines) and lowered (solid lines) position.
Fig. 4 is a close-up view of a means for attaching a chain to
a plate means on the drilling apparatus.
Fig. 5 is a close-up view of an upper sprocket of the drilling
apparatus which is engaged to be driven by a hydraulic motor.
s
An earth drilling apparatus according to the invention is
shown generally in Fig. 1. A service vehicle of a size commonly
used in the utility industry providles a mobile base for drilling
utility pole hales. The apparatus includes a truck designated
generally as 10 having an elongated structure, such as universally
jointed boom 12, mounted on a rotatable carousel 17 at the rear of
the truck. The boom 12 is preferably extensible to reduce the need
for maneuvering the truck 10, for example by telescoping inner and
outer portions, or by an articulating joint near a central part of
the boom. The vehicle has means for providing hydraulic forces
including a hydraulic fluid pump (not shown) which may be driven
by the vehicle's main power source or by an auxiliary power source
mounted on the vehicle. The hydraulic fluid under pressure from
the pump is coupled via suitable valves to extensible cylinders
and/or hydraulic motors and other actuating devices for extending,
raising and lowering the boom, and for rotating the carousel. The
hydraulic pumping and actuating apparatus for the boom 12 can be
of the type conventionally used in boom trucks such as small
cranes, cherry picker lift apparatus, etc.
The vehicle also includes hydraulic couplings for providing
hydraulic forces to a drilling apparatus via couplings, valves and
similar connection means. The vehicle may also have means for
providing pneumatic forces, including an air compressor and an
auxiliary power source for driving the air compressor. The
auxiliary power source for the air compressor and the auxiliary
power source for driving the hydraulic oil pump may be a single
unit.
The utility industry normally employs an auger drill bit (not
shown) for drilling the utility pole holes in all earth formations
except for solid rock, and an auger drill can be mounted on the
apparatus of the invention. The auger drill has a hydraulic motor
at an upper end which is hingedly attached to one end of an arm 13.
The other end of 'the arm 13 is perpendicularly hingedly attached
town outer end 14 of the boom l2. Thus, the arm 13 defines a form
of universal joint mounting whereby the auger drill can be inclined
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9
from vertical in order to drill the pole holes at any desired
angle. Of course the usual pole hole is precisely vertical.
Nevertheless, inclined holes may be needed as well, for example to
anchor a diagonal bracing pole, etc
The drilling apparatus according to the invention can be
operated by removing the auger drill from the commonly used
drilling vehicle from which the auger dangles without support, and
attaching a drill support and powering device as hereinafter
described. The auger drill is easily detached by a skilled
mechanic using ordinary hand or power tools to remove attaching
hardware. In order to retain the universal joint function of the
arm 13, it is preferred to detach the auger drill where the
hydraulic motor connects to the one end of the arm.
As shown in Fig. 2, the earth drilling apparatus of the
invention includes an elongated guide means 20 which preferably
includes two lengths of angle iron 21, 22 having suitable size and
strength to form a rigid structure to support and guide the
drilling means. The lengths of angle iron 21, 22 are rigidly
connected in either contacting or laterally spaced apart
relationship as necessary to achieve desired dimensions. In the
preferred embodiment shown, angle irons 21, 22 are laterally spaced
and the space protectively accommodates part of the structures used
to raise and lower the drilling means. The angle irons may be
connected by bolting, welding, or other suitable means or by
similarly connecting angle irons 21, 22 to end members andJor
intermediate transverse members.
According to the invention, the guide means 20 is removably
attached to the boom 12. Preferably, the guide means is removably
attached to the one end of the arm 13 (the lower or distal end),
mounted on the boom 12. As shown in Fig. 3, an upper end of the
guide means defines a bore 25 for receiving a transverse shaft,
namely shaft 36, shown in Figs. 1 and 2. The upper end of the
guide means may include a pair of spaced apart ear members 27
defining a pair of coaxial holes which form the bore 25 for shaft
36. The holes may be coaxially aligned on either side of a
corresponding bore in the one end of the arm 13. Support bar 36
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is insertable through the coaxially aligned holes which form the
bore 25 and through the corresponding bore in arm 13 for suspending
the guide means as shown in Fig. 2. The support bar may be
retained with locking means such as cotter pins, C-clips, or the
like. In this manner the guide 20 is fixed to arm 13 for lateral
positioning of guide 20, but is movable in a longitudinal direction
relative to the boom 12.
Referring now to Figs. 2 and 3, a drill head 45 is movably
mounted to be advanced or retracted along at least a portion of the
guide means. In a preferred embodiment, a plate means 26 is
movably attached along the guide means, and the drill head 45 is
attached to the plate means such as by threaded fasteners. The
drill head has at least one hydraulic motor and can be a standard
drill head for rock drilling operations such as a drill head made
by the Gill Rock Drill Company. The plate means 26 defines a pair
of opposed internal grooves which are dimensioned to slidingly
receive oppositely extending legs of the angle irons 21, 22. The
plate means 26 may be formed by parallel plate members joined and
appropriately machined to define the opposed grooves between mating
surfaces of the plate members. Alternatively, the plate means may
be an integral part of the drill head. The drill head includes a
rotatable shaft 48 which may be attached in a known manner to a
drill pipe 52, and receives a rock drill bit 56 at a remote, or
lower, end thereof. The rook drill bit is of a type known in the
drilling industry and includes a drilling face 59 having a
plurality af, for example, tungsten carbide or other hard inserts
embedded in the drilling face and protruding therefrom toward the
material to be drilled. The drill bit 56 has a central passageway
for conveying a flow of air to the drilling face 59 in order to
clear the hole of drilling debris as hereinafter described. The
drill bit as shown is oriented to drill a hole vertically downward
as the drill bit is moved toward the earth formation. ~iowever, as
noted above, the guide can be inclined.
The drilling apparatus may also include a percussion tool 63
attached between the rock drill bit 56 and the drill pipe 52 for
producing a reciprocating motion of the drill bit while the drill
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bit is rotating. The drill bit thus cuts and pulverizes the rock
in a single operation, thereby decrea:~ing drilling time as compared
to the same drilling apparatus without the percussion tool. The
percussion tool may be of a type which is generally known in the
drilling industry. Xnown percussion tools typically require a
source of pneumatic pressure for their operation. For this purpose
the percussion tool can be connected to an air compressor mounted
on the vehicle. An air hose is connected at one end to an output
from the air compressor, and at the other end to an air inlet
fitting 46 on the drill head 45, for example, with snap-on
couplings, threaded connectors, etc. An air hose support 49 is
provided to reduce bending stress at the fitting 46 due to the
weight of the air hose, and to maintain the air hose clear of the
drilling apparatus. Each of the drill head 45 and the drill pipe
52 has a central passageway through which air flows to the
percussion tool, and further flows through the central passageway
in the drill bit 56 before exhausting from a central aperture in
the drilling face 59. The air hose between the truck mounted air
compresssor and the air inlet fitting 46 can run along the boom 12
or can be run directly, for example along the ground.
The percussion tool 63 has an external diameter which is
greater than an external diameter of the drill pipe 52. Therefore,
sleeve 54 is preferably attached at an upper end of the percussion
tool. The sleeve 54 is a hollow pipe which has an external
diameter substantially the same as the external diameter of the
percussion tool. The sleeve 54 is disposed external to and coaxial
with the drill pipe 52. The sleeve 54 and the percussion tool 63
define an outer surface of constant diameter from the drill head
45 to the rock drill bit 56. Thus, as a hole is drilled in the
earth, an annular space of constant cross-section is defined
between the drill string outer surface and the wall of the hole.
Air which is exhausted at the drilling face 59 gathers drilling
debris at the bottom of the hole and forces the debris through the
annular space up to the ground surface. The constant cross-section
of the annular space causes the air and debris to be maintained at
a high velocity so that the debris does not fall back down the
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hole.
Means are provided for communicating the hydraulic forces from
the vehicle to the drill head. Hydraulic hose means are attached
at one end to the hydraulic fluid couplings on the vehic:Le,and at
the other end to hydraulic fittings 71 on the drill head.
Control means are provided for controlling the hydraulic forces to
the drill head. The control means preferably include a plurality
of hydraulic pressure control valves 68 which are attached to
brackets supported by the guide means in a location to allow a
drill operator to stand next to the guide means for optimum viewing
of the hole being drilled. Safety shut-off means or pressure
relief means, etc., can also be included.
Means for affixing a lower end of the guide means to the
ground to be drilled are provided in order to resist transverse and
rotative movement of the guide means relative to the drilling axis.
The means for affixing may include anchoring holes in the lower end
of the guide means for receiving pins to be driven through the
anchoring holes into the ground. A preferred embodiment for the
means for affixing as shown in Figs. z and 3 includes a stabilizer
bar 73 attached rigidly to the lower end of the guide means. The
stabilizer bar has at least two sleeves 76 adapted to receive a
pin, dowel or the like, which is hammered or threaded into the
ground. The at least two sleeves 76 each have an axis which
extends parallel to an elongation axis of the guide means. The
sleeves may be formed from short lengths of pipe or the like.
Prior to starting a drilling operation, the guide means is
positioned at the pole hale to be drilled. The at least two
sleeves are used as templates for locating the dowels in the
ground. When the ground has a sufficient top layer of soil, the
dowels may simply be inserted through the sleeves and hammered into
the ground. The dowels are preferably formed from lengths of pipe
having a diameter smaller than an inside diameter of the sleeves,
and can be as long as necessary in view of the character of the
earth into which the dowels are passed to fix the bottom of the
guide means in place. When the top layer of soil above rock is
very shallow, portable rock drills may be used to drill pilot holes
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in the rock before the dowels are hammered into the earth.
The drilling apparatus has means for advancing and.retracting
the drill head over a span along the guide means. The means for
moving includes an upper rota~table sprocket 32 and a lower
rotatable sprocket 33 mounted along 'the span, for example at the
upper and lower ends of the guide means, respectively. A length
of roller chain 18 is looped around and engaged by teeth on the
upper and lower sprockets. The length of chain has ends 58, 59
which are attached to the drill head such as by threaded fasteners
62 from opposite directions along the guide means. As shown in
Fig. 4, one end of the threaded fastener 62 is threadedly engaged
with the chain end 59. A portion of the fastener 62 extends
through a hole in tab 41 attached to the plate means 26, and the
fastener 62 is secured to the tab 41 by nuts 6'7. Tension in the
chain 18 is adjustable by varying the portion of the fastener 62
which extends through the tab 41.
Nteans for rotating at least one of the upper and lower
sprockets are also provided. The means for rotating may be a
further hydraulic motor 82 which receives hydraulic forces from the
vehicle via hydraulic hose means. The hydraulic motor 82 is
preferably operable by controls disposed among the control valves
68. Rotating one of the upper and the lower sprockets via motor
82 exerts a force via the length of chain on the drill head. Thus,
the drill head may be raised or lowered depending upon the
direction of rotation of the sprockets and the resultant direction
of the force exerted by the length of chain. In a preferred
embodiment, as shown in Fig. 5, the motor 82 is a standard
hydraulic motor such as one manufactured by the Braden Winch
Company. The motor 82 operates a drive unit which is mechanically
engaged with the upper spracket 32 to cause rotation of the upper
sprocket upon the application of hydraulic forces to the motor 82.
During a drilling operation, the drill head is gradually
lowered to advance the drill bit 56 into the ground. A great
downward pressure can be exerted on the drill bit as a result of
the hydraulic forces acting through the hydraulic motor 82 to urge
rotation of the associated upper sprocket 32 and cause a high
14
tension in the chain 18.
The drilling apparatus may further include a drill bit guide
85 attached to the guide means for preventing deflection of the
drill bit relative to the plate 26, especially when starting the
hole in the ground. The drill bit guide 85 is formed by a plate
which is attached to the guide means in a plane substantially
perpendicular to the drill pipe, and is preferably attached at the
lower end of the guide means in the vicinity of the percussion tool
63. The drill bit guide defines a hole having a diameter which is
sufficient to permit rotation of the percussion tool therein, while
providing a minimal clearance around the periphery of the
percussion tool for retaining alignment of 'the percussion tool.
Deflections of the drill bit are .resisted by contact between the
percussion tool and an inside edge of the drill bit guide. The
drill bit guide is described in U.S. Patent No. 3,370,285 to
Andersen et al.
