Note: Descriptions are shown in the official language in which they were submitted.
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SCREW-TYPE, IN-GROUND ANCHOR DEVICE
TECHNICAL FIELD
This invention relates to an apparatus and method of
anchoring uprights in the ground and, more particularly, to
a removable screw-type, in-ground anchor device that provides
a secure foundation for uprights in any type of soil without
using concrete.
BACKGROUND ART
At present, most uprights such as fence posts and sign
posts are anchored in the earth by digging or drilling a hole
in the ground, pouring concrete in the hole, and securing the
base of the upright in the concrete until it dries. The
process is tedious, labor intensive, and causes additional
delays due to the drying and curing time of the concrete .
Additionally, the uprights are extremely difficult or
impossible to remove if the fence or sign post needs to be
taken down or repositioned at a future date.
Past attempts to improve the foundation and anchoring
of uprights have met with only limited success. A typical
attempt is described in U.S. Patent No. 5,295,766 to
Tiikkainen. Tiikkainen discloses a foundation for uprights
that includes a tubular drive-shaft that is equipped with a
large helical auger at the base. In operation, a conical
section above the auger serves to compact a soil layer
softened by the rotation of the helical auger. However, the
diameter of the auger is much greater than the widest
diameter of the conical section and the outside diameter of
the tubular drive-shaft. Therefore, the auger softens the
soil surrounding the drive-shaft for a considerable distance
beyond the outside diameter of the shaft. The conical
section is then unable to compact the soil sufficiently to
provide a secure foundation for the upright. Additional
steps such as pouring concrete must be taken to reinforce the
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foundation. Thus, the soil conditions in which Tiikkainen
can operate are limited, and Tiikkainen does not teach or
suggest a screw-type, in-ground anchor device that provides
a secure foundation for uprights without the use of
reinforcing concrete.
In order to overcome the disadvantage of existing
solutions, it would be advantageous to have a removable
screw-type, in-ground anchor device that provides a secure
foundation for uprights such as fence posts, sign posts, and
street lights in any type of soil without using concrete.
The present invention provides such a device.
DISCLOSURE OF THE INVENTION
Tn one aspect, the present invention is a removable
screw-type, in-ground anchor device that provides a secure
foundation for uprights such as fence posts, sign posts, and
street lights in any type of soil without the necessity of
using concrete. The anchor device includes a generally
cylindrical drive shaft with a 'set of screw threads
( f 1 ightings ) mounted near the lower end . The drive shaf t
includes a cylindrical housing portion of a first diameter
at an upper end of the drive shaft for supporting the above-
ground upright. A shallow-sloped conical portion connects
the housing portion to a tip portion that has a second
diameter substantially less than the first diameter. The
conical portion has a surface with a diameter that decreases
from the first diameter to the second diameter over a
longitudinal distance that provides a slope to the surface
of less than 20 degrees, and preferably in the range of 5-10
degrees. The flightings are attached to the tip portion and
have a third diameter that is approximately equal to the
first diameter. The flightings operate in soil to screw the
anchor device into the ground when the device is rotated.
In another aspect, the present invention is a screw-
type, in-ground anchor device for anchoring an above-ground
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upright in all types of soil. The anchor device includes a
cylindrical upper housing portion with a diameter sized to
accept the above-ground upright. A set of flightings are
mounted near a bottom end of the anchor device, and impart
downward force on the anchor device when the anchor device
is rotated. The flightings having a diameter approximately
equal to or less than the diameter of the housing portion.
The flightings disrupt the soil in their wake, and a conical
portion Ilhaving a slope of less than 20 degrees, and
preferably in the range of 5-10 degrees, outwardly compresses
the soil in the wake of the flightings. The outward
compression of the soil creates a tightly compressed soil
shaft having the same diameter as the housing portion.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and its numerous
objects and advantages will become more apparent to those
skilled in the art by reference to the following drawings,
in conjunction with the accompanying specification, in which:
FIGS . lA and 1B are elevational views of two embodiments
of the screw-type, in-ground anchor device of the present
invention;
FIG. 2 is a perspective view of the top of the upper
housing portion of the anchor device and a T-handle manual
insertion tool;
FIG. 3 is a perspective view of the top of the upper
housing portion of the anchor device in an alternative
embodiment and an X-handle manual insertion tool;
FIG. 4 is a top plan view of a first embodiment of a
manual insertion wheel for use with the anchor device;
FIG. 5 is a top plan view of a second embodiment of a
manual insertion wheel for use with the anchor device; and
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FIG. 6 is a perspective view of an adapter configured
for use with a core drill chuck to mount a T-handle on a core
drill for machine insertion of the anchor device into the
ground.
MODES FOR CARRYING OUT THE INVENTION
FIGS . lA and 1B are elevational views of two embodiments
of the anchor device 10 of the present invention. The
present invention is a screw-type, in-ground anchor device
for receiving above ground uprights such as vertical posts,
poles, or tubing. The device comprises a tip portion 11,
flightings 12, a shallow-sloped conical portion 13, and a
cylindrical upper housing portion 14 for receiving the above
ground upright. The flightings have a diameter that is
approximately equal to, but preferably slightly less than,
the diameter of the upper housing portion. For example, in
one embodiment designed for supporting fence posts, the
outside diameter of the upper housing portion is 2-7/8 inches
and the diameter of the flightings is 2-5/8 inches.
The flightings may have a spacing of approximately f-
inch (i.e., 1-inch pitch) which causes the device to move
inch into the ground for each revolution. In the fence post
embodiment, the flightings extend over a longitudinal
distance of approximately 4-inches. The flightings are
welded to the tip portion 11 and partially up the conical
portion 13. The weld overlaps the tip of the conical portion
to provide a stronger weld.
As the device is screwed into the ground, the conical
portion 13 works as a packing device. The flightings 12
disrupt the soil only within the diameter of the upper
housing portion 14, and the conical portion then outwardly
compacts the soil to form a tightly packed soil shaft that
tightly encloses the device 10 and holds it solidly in place.
The conical portion has a shallow slope of less than 20
degrees as shown in FIG. lA, and preferably in the range of
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5-10 degrees from the vertical as shown in FIG. 1B. The
shallow slope causes the soil to be compacted slowly as the
device moves into the ground. Some looser soils may be
compacted with conical slopes up to 20 degrees, but for
denser soils, slopes of 5-10 degrees are preferable. Since
the soil is being gradually compacted, less downward force
must be generated by the flightings, thereby enabling the
smaller fsightings of the present invention to be utilized.
If the slope of the conical portion is steeper, as in
some prior art devices, the flightings must generate more
downward force in order to move the device through the ground
and outwardly compact the soil in a shorter distance. Under
these conditions, the smaller flightings utilized in the
present invention would strip out the soil and spin uselessly
in the hole. Prior art devices made the mistake of
overcoming this problem by making the flightings larger so
that they could produce more force. Prior art designers also
had the mistaken belief that large flightings would provide
a stable base for the device. However as noted above, large
flightings have the detrimental effect of disrupting the soil
in a large area surrounding the device as it moves into the
ground, producing a less stable anchor. Therefore, reducing
the diameter of the flightings to a diameter less than the
outside diameter of the upper housing portion, and decreasing
the slope of the conical section to less than 20 degrees
produces the unexpected result of a more stable anchor.
Thus, the present invention provides the dual features
of (1) disrupting the soil only within the diameter of the
device itself, and (2) gradually compacting the disrupted
soil outwardly as the device is pulled into the ground by the
rotating flightings. In combination, these features result
in a tightly packed soil shaft the exact diameter of the
upper housing portion of the device.
The overall length of the device 10 is determined by the
diameter and length of the vertical upright to be mounted in
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it, and the type of soil. For stability, the housing portion
14 should be long enough to accept about 25-30% of the length
of the vertical upright. The length of the conical portion
13 is derived from the outside diameter of the upper housing
portion (variable), the diameter of the tip portion (3/4
inches), and the 5-10 degree slope of the cone. For the
fence post embodiment, the conical portion is approximately
9 inches f rom the bottom of the housing portion 14 to the top
of the tip portion 11.
The preferred embodiment of the present invention
utilizes the tip portion 11 to provide vertical stability
when the anchoring device is first started into the ground.
In an alternative embodiment, the tip portion may be omitted,
and the flightings attached to the lower part of the conical
portion 13. However, without the tip portion, it is more
difficult to keep the device plumb. The tip portion may be
constructed by machining a point on a 3/4-inch steel rod.
In addition, one or two opposing vertical notches 15 are
placed in the tip at the leading end to initially disrupt the
soil in dense soil conditions, and to enable the tip to break
up small rocks or dislodge them as the device penetrates the
soil. Experimentation has shown that if the tip has a plain
point, any impediment in the soil, such as a small rock,
tends to deflect the anchoring device from the vertical as
it is being inserted. When the tip is notched, however, the
rock is either broken away or pushed to the side. If the tip
hits the rough edge of a rock, the notch chips the rock, and
the device remains plumb. Smooth rocks are pushed aside.
As the device continues into the ground, the rock is pushed
to the side by the conical portion, and does not affect the
proper orientation of the device.
Additionally, if a plain tip hits an impediment such as
a gas line, PVC water pipe, or electrical line, even though
the object is smooth and rounded, the tip is likely to damage
the pipe or line. However, when the notched tip hits a
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smooth rounded object such as a pipe or line, experimentation
has shown that the tip pushes the pipe or line to the side
and does not damage it.
In the fence post embodiment, the length of the rod
making up the tip portion 11 is 5-1/2 inches from the tip of
the conical portion 13 to the leading end. The part of the
tip portion that extends beyond the flightings is about 2-1/2
inches . .This conf iguration is for a tighter soil such as
clay or black dirt. Sand, sandy loam, or gravel require
different configurations with a longer tip. The longer tip
provides more stability in looser soils.
Longer tip portions may also be used for anchor devices
being inserted into lake bottoms or river beds. Uprights
that go into a lake bottom or river bed currently have to be
pile-driven into the soil under the lake or river. For most
lake or river beds, there is a clay layer of the soil that
actually holds the water, and the local water table is some
distance below the clay layer. Accurate information about
the depth of the water table is often not available,
therefore, the distance from the bottom of the lake to the
water table is not known. Pile driven poles driven into the
bottom of a small pond may actually penetrate the clay layer,
causing the pond to drain into the water table below.
The present invention, however, can be screwed into the
lake bottom much quicker, and forms a plug in the underlying
clay layer, thereby preventing the pond from being
inadvertently drained. A coupling such as that described
later in FIG. 6 may be utilized to attach the present
invention to a drill. For different water depths, additional
pipe sections may be added as required, much like drill stem
pipe on an oil rig. For anchor devices designed for lake
bottoms or river beds, the tip portion 11 may be as long as
12 or 13 inches. When the tip portion starts to penetrate
the clay layer, the rotating flightings 12 screw into the
clay soil, and the conical portion 13 tightly compacts the
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clay around the device. This creates a tight plug, providing
a solid anchor for an upright while preventing the draining
of the pond.
The diameter of the anchoring device may vary in order
to support uprights of various diameters. For different
diameters, the dimensions of the device are scaled up or down
so that the anchor device retains approximately the same
proportiqns. For example, while the conical portion of the
fence post embodiment has a maximum outside diameter of 2-7/8
inches and a length of 9 inches, a slightly larger version
may have a maximum outside diameter of 3-1/8 inches, and a
conical portion 11 inches long, thus maintaining the slope
of the conical portion at approximately 5-10 degrees. Known
applications may vary from 2-3/8 inches (inside diameter) for
a fence post to 8 inches (inside diameter) for a street light
or telephone pole. For highway signs, the inside diameter
of the housing is approximately 4 inches.
For larger diameters such as 8 inches, it may be
necessary to pre-drill a central bore hole due to the amount
of soil to outwardly compact. The central bore hole may be
as large as 6 inches in diameter and 24 inches deep. The
depth of the central hole is less than the length of the
device since the flightings 12 have to be screwed into the
soil at the bottom of the bore hole in order to cause the
compacting by the conical portion 13.
Uprights such as street lights commonly mount on a base
plate. For uprights mounting on a base plate, the base plate
is mounted on the top of the upper housing portion, and the
street light, instead of being inserted into the housing, is
mounted on the base plate.
The preferred embodiment of the anchoring device 10 is
made of 1/4-inch rolled steel, although the thickness and
composition may vary according to the soil conditions and the
size of the upright. The device may also be constructed of
a hard polymer or a polymer/steel-strand mixture that can be
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formed in an injection mold. The preferred embodiment is
hollow from the top of the upper housing portion 14 to the
bottom tip of the conical portion 13. Alternatively, the
conical portion may be solid, but it makes the device heavier
and more expensive. In fact, for uses where a mounting plate
is used on the top to mount uprights such as a light pole,
the entire device may be solid, but once again, it makes the
device heavier and more expensive.
The anchoring device can be inserted manually with an
insertion tool or by machine. FIG. 2 is a perspective view
of the top of the upper housing portion 14 of the anchor
device, showing the void 20 formed inside the housing portion
14, and a T-handle manual insertion tool 21. The manual
insertion tool may be a piece of pipe or steel rod that can
be used as a T-handle when placed in the insertion slots 22
on the top of the housing. One or more people then rotate
the device with the T-handle. A level indicator 23 may be
mounted on the T-handle to ensure the anchoring device
remains plumb.
FIG. 3 is a perspective view of the top of the upper
housing portion 14 of the anchor device in an alternative
embodiment and an X-handle manual insertion tool 31. In this
embodiment, the anchoring device 10 is provided with four
insertion slots 22 on the top of the housing at 90-degree
spacing. The X-handle is equipped with a leveling device
which may be, for example, a circular bubble-level 32 mounted
in the center of the X-handle. Alternatively, two opposing
slots can be cut to a depth twice the diameter of the pipe,
so that one T-handle can be placed in the deeper slots, and
a second T-handle can be used in the shallow slots in a
perpendicular orientation.
FIG. 4 is a top plan view of a first embodiment of a
manual insertion wheel 41. In this embodiment, a loop 42 is
mounted at the ends of a plurality of radiating spokes 43 to
create a manual insertion handle similar to a steering wheel.
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Here again, a circular bubble-level 32 may be mounted in the
center of the wheel to keep the anchoring device plumb as the
device is inserted into the ground.
FIG. 5 is a top plan view of a second embodiment of a
manual insertion wheel 51. In this embodiment, a loop 52 is
mounted near the ends of a plurality of radiating spokes 53
to create a manual insertion handle similar to a ship's
wheel. Here again, a circular bubble-level 32 may be mounted
in the center of the wheel to keep the anchoring device plumb
as the device is inserted into the ground.
FIG. 6 is a perspective view of an adapter 61 configured
for use with a core drill chuck 65 to mount a T-handle
similar to the T-handle 21 on a core drill 66 for machine
insertion of the anchor device into the ground. For
insertion by a machine, a hand-held or crane-mounted core
drill 66 may be utilized to rapidly insert the device into
the ground while reducing human labor. The adapter 61
includes a shank 62 which is inserted into the core drill
chuck 65. The shank is mounted to a cylindrical body 63 with
mounting brackets 64. The cylindrical body of the adapter
has an outside diameter that is equal to the inside diameter
of the upper housing portion 14 of the anchor device 10. In
operation, the cylindrical body 63 is inserted into the upper
housing portion 14, and the T-handle 21 is inserted into the
insertion slots 22. The core drill is then used to insert
the anchor device into the ground. Generally, a hand-held
core drill may be used to insert anchoring devices up to
approximately 3 inches in diameter. The crane-mounted core
drill is preferable for larger diameters. A power takeoff
(PTO? auger on a tractor can also be used to insert anchoring
devices up to approximately 5 inches in diameter.
The anchoring device is reusable, and can be easily
extracted from the ground and reinserted in a new location.
This makes the device useful for temporary signage, fencing,
or utility poles, etc. Reversing the direction of rotation
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causes the flightings 12 to back out until they reach the
void created by the previous position of the conical portion
13. The device can then be simply lifted out of the hole.
It is thus believed that the operation and construction
of the present invention will be apparent from the foregoing
description. While the apparatus shown and described has
been characterized as being preferred, it will be readily
apparent that various changes and modifications could be made
therein~without departing from the scope of the invention as
defined in the following claims.
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