Note: Descriptions are shown in the official language in which they were submitted.
CA 02364666 2001-12-07
TEM Docket No. 235.5
TITLE: IMPROVED METHOD AND APPARATUS FOR CUTTING AND
s SPLITTING PIPE
FIELD OF THE INVENTION
The present invention relates to a cutting, expanding, and re-piping apparatus
that
permits the in situ replacement of an existing corrugated metal pipe or thin
walled pipe
so used for culverts by cutting and expanding the host pipe to permit a re-
placement pipe to
be drawn through the host pipe. More specifically, the invention is directed
for use on
corrugated metal piping or thin-wall piping used for culverts under roads
where the
culvert has deteriorated over time, has lost some of its structural integrity
or has partially
collapsed, thereby losing its original circular shape.
is
BACKGROUND OF THE INVENTION
Existing underground or buried pipe, such as culverts or water and gas mains,
are
typically replaced for various reasons, such as the impending expiry of the
pipe's service
life, the failure or deterioration of the existing pipe, and the insufficient
size/capacity of
2o the existing pipe. Removal of such "old" pipe is avoided, if possible, to
avoid prohibitive
excavation costs and other related expenses and inconveniences, such as
repaying a road
surface and closing the road to vehicular traffic.
Various devices and techniques have therefore been developed for in situ
replacement of buried pipe to reduce costs and inconveniences. Examples of
such tools
2s to cut through an existing pipe from within, particularly those employing a
form of
cutting means such as cutting wheels or blades, are shown in US patents
5,098,225
(Rockower et al.) and 6,149,346 (Takamatsu et al.). However, a disadvantage of
such
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CA 02364666 2001-12-07
prior art cutting tools is that they are dependent upon the concentricity and
structural
integrity of the pipe since such tools utilize offsetting forces to attain the
cut or split. In
Rockower and Takamatsu the cutting wheels or bodies will not cut through a
longitudinal
section of deteriorated pipe unless the cutting wheels/bodies have sufficient
radial force
s to push through the pipe. For instance, in Rockower, the cutting wheels at
the bottom of
the cutting tool will not be able to push downwardly and cut through a bottom
portion of
intact pipe if the opposed ceiling portion of the pipe has deteriorated and
does not provide
sufficient support for such downward forces. Hence, it is difficult, if not
impossible, to
expediently and properly split a deteriorated pipe lacking structural
integrity with current
so cutting tools since the pipe will lose its concentricity and be incapable
of supplying the
necessary offsetting forces.
In another type of pipe replacement apparatus shown in US patent 5,112,158
(McConnell), a crushing head has circumferentially disposed tapered blades for
crushing
an existing pipe. Such apparatus will also encounter difficulties with
deteriorated pipe
1s because the crushing head will be forced off centre of the pipe and may jam
if the blades
encounter non-uniform resistance from the deteriorated pipe walls.
What is therefore desired is a novel pipe cutting tool that overcomes the
limitations and disadvantages of the existing tools. Preferably, it should be
able to cut
through a pipe regardless of the pipe's structural integrity. All of the
required cutting
2o forces should be offset internally within the cutting tool itself. The same
cutting tool
should be capable of use for various sizes of pipes, to avoid the cost of
stocking various
sizes of cutters for different pipes. The tool should be adapted to cut
through external
culvert obstructions, such as joining clamps, which traditionally have been
problematic
for conventional tools. Further, a user should have the option of using more
than one
25 cutting tool concurrently in a pipe to provide a desired number of
longitudinal cuts, so as
to easily and quickly adapt to the size and integrity of the pipe, and to the
existing soil
conditions.
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SUMMARY OF THE PRESENT INVENTION
According to the present invention, there is provided in a first aspect a
cutting
apparatus which is adapted to cut corrugated metal pipe or thin walled pipe
regardless of
the pipe's concentricity and structural integrity as all required forces are
offset internally
within the cutting tool. The apparatus accomplishes this with a series of
cutting wheels,
stepped in stages, mounted in a frame which envelopes one or more portions of
the pipe
wall and is drawn through the pipe to cut a specific logitudinal portion of
the pipe without
relying on or touching other portions of the pipe. The present apparatus
relies on pressure
between its frame and cutting wheels when pulled along the wall of the pipe,
thus
1o eliminating the pipe's size and total structural integrity as prereqisites
for using the device
on the pipe.
In particular, the first aspect of the present device includes a guide for the
device's
frame which provides several advantages, including:
providing the frame with a larger area of contact with the pipe wall to allow
the
cutter apparatus to follow the pipe wall regardless of the pipe's shape;
creating a channel for the cutter wheels beyond the diameter of the pipe; and,
preventing debris from falling into the cavity of the pipe while cutting the
pipe
wall.
The leading edge of the frame of the present apparatus is hardened and
sharpened
2o to shear any exterior bolts or bonding used to hold pipes together. Behind
the cutter
wheels is a sharpened, hardened ripper to ensure any uncut metal is severed.
For
mobility, the cutter head is attached to a traveling link, connected to a pull
string, which
allows the head to follow along the pipe wall independently of any
irregularities. A
chassis attached to the pull string is adjustable for different diameter
culverts to allow for
alignment of the cutter apparatus with the pipe wall.
An expanding head travels behind the cutting apparatus to spread the cut pipe
and
make room for a new replacement pipe to be drawn through.
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CA 02364666 2001-12-07
All of the aforementioned components of the present invention are connected to
each other at end of a pull string.
Depending on soil and pipe conditions, one or more cutting tools can be
employed
at the end of the pull string to provide a corresponding number of
longitudinal cuts
s through the pipe.
In a second aspect of the invention an improved expanding head provides a more
tapered cone head and elongate ribs spaced about the head to facilitate
movement through
the pipe being replaced. In particular, the improved head should provide for a
better
distribution of forces exerted when spreading the pipe to avoid undue
crinkling and
1o buckling of the pipe.
Further, an alternate cutting apparatus is provided that is particularly
suited for
silty soils with a considerable rock content. Among other features, the
apparatus has
fewer cutting wheels which are on average generally larger than those of the
aforementioned cutting apparatus. Slots have been added circumferentially
about the
15 cutting wheels to urge the wheels to rotate as the cutting apparatus is
advanced along the
pipe. The guide is made narrower and has bevelled corners to urge dirt and
rocks away
from the cutting wheels. The channel's length is curtailed to allow a pressure
drop in any
soil moving through the mouth of the apparatus over the cutting wheels.
Reinforcement
plates are added to improve resistance to side loads and better distribute
stress
zo concentrations behind the throat of the apparatus.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
Embodiments of the invention will now be described, by way of example only,
with reference to the accompanying drawings, wherein:
z5 Figure 1 shows a cutting, expanding and re-piping assembly according to a
first
embodiment of the present invention in operation, namely a pull string pulling
a cutting
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tool through an existing culvert, and an expanding head and collar with a new
culvert
being drawn therewith;
Figure 1 a is a view similar to fig. l showing a shorter coupler for using the
cutting
tool in an existing culvert of smaller diameter;
s Figure 2 is a more detailed elevational view of the cutting tool of fig. l ;
Figure 2a is a view similar to fig.2 showing the frame of the cutting tool
with
cutting wheels removed;
Figure 3 is a plan view from above of the cutting tool of fig.2;
Figure 4 is a view from below of the cutting tool of fig.2;
1o Figure 5 is a end view from the front of the cutting tool of fig.2;
Figure Sa is a view similar to fig.5 showing the frame of the cutting tool
with the
cutting wheels removed;
Figure 6 is a cross-sectional view along line 6-6 of fig.2;
Figure 7 is a detailed elevational view of one of the cutting wheels of the
cutting
1s tool of fig.2;
Figure 8 is a cross-sectional view of the cutting wheel of fig.7;
Figure 9 is an end view looking into a culvert with three cutting tools
employed
therein;
Figure 10 shows a second embodiment of the cutting tool;
2o Figure 11 is a plan view from above of the cutting tool of fig.10;
Figure 12 is a view from below of the cutting tool of fig.10;
Figure 13 is a cross-sectional view along line 13-13 in fig.l0 looking
backward
along the cutting tool;
Figure 14 is a side elevational view of an improved expanding head;
2s Figure 15 is an end view, from the right side in fig. 14, of the improved
expanding
head;
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Figure 16 is a detailed elevational view of one of the cutting wheels of the
cutting
tool of fig.10 showing slots thereabout; and,
Figure 17 is a cross-sectional view of the cutting wheel of fig.l6.
s LIST OF REFERENCE NUMERALS IN DRAWINGS
cutting and spreading
apparatus
12 existing culvert/pipe
14 centerline of 12
10 16 ground/soil
18 new culvert/pipe
pull string
22 chassis portion of 20
24 coupling plate
1s 25 bolts
26 travelling block
expanding head/spreader
32 collar
cutter of 10 (first
embodiment)
20 41 frame of 40
42 nose of 40
44 lower jaws
46 upper lip
47 edge of 46
25 48 mouth
guide
SOa, SOb plates of 50
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52 longitudinal channel
54 throat
56 ripper
58 leading edge of 46
58a,
58b
portions
of
58
60 handle
62 bolt holes in 44
70 cutting wheels
70a-7 0e first to last cutting
wheel
72 outer perimeter of 70
74 nut and bolt arrangement
76 bore
130 improved spreader
131 head of 130
132 screws
134 ribs (longer)
135 ribs (shorter)
136 nose of 130
137 tail of 130
138 troughs
140 cutter (second embodiment)
141 frame of 140
142 nose
144 lower jaws of 141
2s 146 upper lip of 141
147 downwardly extending portion
of 146
148 mouth
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150 guide
150a, 150b plates
of 150
151 bevelled edges
152 channel
s 153 end of 152
154 throat
164 reinforcing
plates
170a first cutting
wheel
170b second cutting
wheel
172 cutting edge
173 slots
174 nut and bolt arrangement
175 tapered edges
176 bore
is 177 sloped portions
of 172
178 hub portion
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DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Figure 1 shows an apparatus for cutting and spreading pipe according to a
first
embodiment of the present invention, generally designated by reference numeral
10. An
important feature of the apparatus is the cutting head 40, which may also be
referred to as
a "cutting tool", "cutter assembly" or simply a "cutter". The cutter 40 is
shown being
drawn along the wall of an old, or existing, culvert 12 by a pulling means
such as a pull
string 20. The existing culvert 12, also referred to herein as a "pipe", may
comprise
oil/gas pipelines, water lines, sewer pipes, gas mains, and the like, which
are buried in the
ground 16 or are located above-ground. The cutting tool 40 is best suited for
use on
1o metallic pipes that are traditionally difficult to cut, such as corrugated
metal pipe.
However, it is also well suited for smooth walled metal pipes and, as will be
appreciated
later, pipes of different materials.
The expanding head 30 of the present invention shown in fig.l may also be
referred to as a "spreader tool" or "spreader". It has a conical head 31 of
conventional
design and is linked to the pull string 20 for travel behind the cutter 40
through the
existing cut culvert to further expand and spread the culvert and surrounding
soil as is
known in the art. The surface of the head is typically inclined at an angle
"A1" of about
15 degrees. The spreader 30 makes room for a new/replacement corrugated
culvert/pipe
18. The new culvert 18 is connected behind the spreader 30 via suitable means,
such as a
2o collar 32. In addition, the spreader 30 may take other, non-conical shapes,
depending on
the configuration of the new pipe to be installed.
In an alternate embodiment of the spreader 130 shown in figs.l4 and 15, the
device is improved by reducing the angle of inclination "A2"of the cone head
131 to
about 7.5 degrees to better distribute pressures between the cone and the
culvert and to
avoid crinkling of the culvert as it is being spread. A series of spaced
elongate ribs 134
and 135 are also fixed to the surface of the head, as by screws 132 to
facilitate
replacement of ribs in the field if need be. The longer ribs 134 extend along
the entire
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length of the head from its nose 136 to the tail 137, whereas the shorter ribs
135 do not
extend to the nose 136 to accommodate the conical shape of the head. Good
results have
been achieved using bars made of nylon, such as NYLATRON, which keep the cone
head
from gripping or snagging on the interior surfaces of culverts, which are
often galvanized.
s It will be appreciated that bars of other materials may also be suitable.
The troughs 138,
or spaces, created between the ribs 134, 135 facilitate movement of soil along
the head by
providing a means for dirt and other debris to escape from the pipe 12 past
the expanding
head for deposit outside the new culvert 18 being drawn in.
Referring again to the first embodiment shown in fig.l, the cutter 40,
expanding
1o head 30, collar 32 and new culvert 18 are all operatively engaged to the
end of the pull
string 20 which is located generally along the longitudinal centerline 15 of
the old culvert
12. The pull string 20 is pulled at a downstream location of the old culvert
by suitable
pulling means for exerting adequate force to pull the entire assembly through
the ground.
An important feature of the pull string 20 is a triangular coupling plate 24
fixed to the
is rigid chassis 22 by suitable means, such as bolts 25. A traveling link 26
is pivotally
coupled at one end to the top of the coupling plate 24 and at the other end to
the nose of
the cutter at 42. As will be appreciated better later, the link 26 provides
the cutter 40 with
some freedom of movement radially to allow the cutter to follow corrugations
and other
imperfections and irregularities on the old culvert wall 12. The height of the
coupling
2o plate 24, as well as the length of the link 26, may be appropriately varied
to fit the cutter
in culverts of various sizes/diameters. For example, the shorter ("shallower")
coupling
plate 24a in fig. l a would be used for a pipe of smaller diameter than the
taller plate 24
used for the larger pipe of fig. l .
Another important feature of the present invention is the configuration and
2s function of the cutter, as shown in fig.l and in greater detail in figs.2
to 8. The location
of the various features of the cutter relative to each another will be
described based on the
orientation of the cutter at the top of the culvert as shown in the figures.
It should be
CA 02364666 2001-12-07
understood that the described locations would change for a cutter oriented in
a different
manner, say upside down on the lower part of the old culvert.
The cutter 40 has a frame 41 (as best seen in figs. 2a and Sa) with a series
of
metallic cutting wheels, generally indicated by 70 in fig.2, spaced in tandem
relationship
s along a pair of lower elongate jaws 44 of the frame 41. Although it is
contemplated that
hardened steel wheels will be most commonly used, wheels made of other
suitable
materials, such as ceramic, may be employed for other applications. The frame
has an
opposed upper elongate lip 46 spaced above the jaws 44 to define an elongate
longitudinal mouth 48 of suitable size to accept most thicknesses of culvert
walls 12.
to Two elongate plates SOa and SOb, one extending transversely from either
side of the lip
46, form a frame guide 50 above the mouth 48 along most of its length. The
guide 50
provides an enlarged area of contact between the culvert wall and the frame to
make it
easier for the frame to follow the culvert wall regardless of its shape. The
bottom surface
of each plate SOa, SOb extends slightly below the edge 47 of the lip to form a
longitudinal
is channel 52 (best viewed in figs.2 and 5) for the back cutting wheels which
extend across
the mouth and beyond the radial extent of the culvert's wall. The guide 50
also prevents
debris, such as soil from the ground above the pipe, from falling past the
cutter into the
inner cavity of the culvert being cut open.
The cutting wheels 70, which are individually designated by reference numerals
20 70a to 70e, are rotatably mounted along the jaws 44 by suitable means, such
as the nut
and bolt/axle arrangement 74 which operationally engages the wheel's bore 76,
shown in
figs.6-8. The wheels 70a-70e are arranged so that they are stepped in stages
upwardly
toward the lip 46, and more particularly toward the channel 52, progressively
from the
mouth's front opening back towards the throat 54. In the first embodiment the
outer
25 perimeter 72 of the first cutting wheel 70a (which first engages the wall
of the existing
culvert wall as it enters the mouth) extends the least distance from the lower
jaws 44 into
the mouth 48. In contrast, the outer perimeter of the last, or fifth, cutting
wheel 70e
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extends the furthest from the jaws 44 and across the mouth 48 into the channel
52 of the
upper lip, in close proximity to the ceiling of the channel. In the first
embodiment, the
first three wheels 70a-70c are of the same size, but the bolt holes 62 (see
fig.2a) are
spaced progressively closer to the mouth 48 to bring the perimeter of the
cutting wheels
s 70a-70c progressively closer to the upper lip. The fourth cutting wheel 70d
is of greater
diameter than wheels 70a-70c so that its outer perimeter is yet closer to the
upper lip than
wheel 70c. Finally, the fifth cutting wheel 70e has a greater diameter than
wheel 70d to
bring its perimeter closest to the frame's upper lip. It will be understood
that other
configurations of wheel sizes and bolt hole locations are possible to achieve
a progressive
1o cut of the pipe wall within the mouth 48, as for example with the second
embodiment of
the cutter described below.
As the cutter 40 is drawn into contact with the culvert wall, the cutting
wheels
apply a progressively greater pressure on the wall to cut therethrough. By the
time that
the last wheel 70e engages the cut being formed in the wall, the wall should
be at least
1s nearly or fully severed. As a "fail-safe" precaution, the inclined elongate
throat 54
extends from the back of the mouth 48 behind the last cutting wheel 70e to
present a
hardened, sharpened lower edge, termed a "ripper" 56. The ripper ensures that
any uncut
culvert wall that might pass the last wheel 70e will be severed as the cutter
is pulled
through the existing culvert.
2o The leading edge 58 of the lip 46 has an upward pitch from the front to the
back
of the frame 40, with a steeper nose portion 58a and a more gradually sloped
spinal
portion 58b. The leading edge is hardened and sharpened for shearing any
exterior
obstructions that are encountered along the culvert's wall, such as exterior
bolts or
banding for joining sections of the culvert, and for pushing aside the ground
through
2s which the frame 40 may travel. An elongate hole 60 further along the spine
toward the
back of the frame forms a handle for a user to grip and lift the tool by hand.
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A second preferred embodiment of the cutter 140 shown in figs 10 to 13 is
particularly suited for use in soils with a substantial content of clay and
rocks of various
sizes and to cut couplings joining segments of a culvert. The cutter 140 is
similar to the
cutter 40, and for this reason will not be described again in great detail.
For ease of
s reference, the reference numerals used in figs. 10-13 are similar to those
used to describe
the components of the cutter 40, with the addition of a prefix "1". Some of
the
differences of the cutter 140 are set out below.
Only two cutting wheels are provided toward the back portion of the mouth 148.
A first cutting wheel 170a rotatably mounted to the lower lip 144 is located
ahead of a
1o second cutting wheel 170b of larger diameter rotatably mounted at the back
of the mouth
adjacent the throat 154. The cutting wheels employed have on average a larger
diameter
than the wheels 70a-70e in that the first cutting wheel 170a is at least as
large as the fifth
cutting wheel 70e of the first embodiment. The wheels 170a, 170b are also
arranged so
that they are stepped in stages upwardly toward the upper lip 146 and the
channel 152,
15 progressively toward the back of the mouth 148. The outer perimeter of the
last, or
second, cutting wheel 170b extends the furthest from the lower jaws 144 across
the
mouth into the channel 152, whereas the first wheel 170a remains marginally
out of the
channel 152. Good results have been achieved using a 5.5 inch (about 140 mm)
diameter
wheel 170a and a 6.5 inch (about 165 mm) diameter wheel 170b.
2o Referring to figs. 16 and 17, the wheels 170a, 170b are further improved by
scoring a number of slots 173, or grooves, generally evenly spaced about the
circumference of each wheel just below and to either side of the outer
perimeter 172, or
"cutting edge". Each slot 173 preferably extends from the sloped portion 177
of the
cutting edge onto the surface of the radially extending hub portion 178. The
slots 173
2s engage the culvert wall as it is being cut to urge the wheel to turn as the
cutter is pulled
through the culvert. As opposed to having the wheel remain stationary and
exposing the
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CA 02364666 2001-12-07
same cutting surface to the culvert wall, the present wheels 170a, 170b rotate
along the
culvert wall for more uniform contact and wear of the cutting edge.
The nut and bolt arrangement 174 (figs. 10-13) has also been altered to
provide a
shallower transverse profile (as seen in figs.l2 and 13) closer to the lower
jaws to help
avoid snagging on sharp edges or protruding portions of the culvert. The nuts
are flatter
and do not extend as far out from the jaws as the nuts 74 of the first
embodiment, and the
outer edges 175 are tapered and kept as smooth as possible.
The channel 152 does not extend forwarly out of the mouth 148 but is curtailed
at
153 by a downwardly extending portion 147 of the lip 146 to lessen the amount
of dirt
so entering the channel as the cutter is pulled forwardly through the soil.
The lip portion 147
urges rocks and dirt away from the channel 152, and the channel allows a
pressure drop in
any soil progressing through the open mouth 148 and over the wheels 170a,
170b.
Reinforcing plates 164 behind the throat 154 on either side of the neck of the
cutter's frame 141, as shown in fig.l0, help resist side loads and relieve
stress
concentrations in that area of the frame during operation.
Each of the elongate plates 150a and 150b of the guide 150 have been narrowed
(i.e. reduced transversely as viewed in fig.l3), and outwardly sloped beveled
edges 151
have been provided near the mouth 148 to urge rocks and dirt away from the
cutting
wheels 170a, 170b to reduce soil resistance and avoid snagging on rocks. The
outside
2o edges 145 of the lower jaws 144 are also provided with outwardly sloped
bevels to
likewise urge rocks and dirt away from the cutting wheels 170a, 170b.
The jaws 144 have been tapered toward the nose 142 to reduce the weight of the
cutter. This tapering is possible due to the reduction in the number of
cutting wheels
employed and their set back away from the nose area.
As shown in fig.9, more than one cutter tool may be mounted on an existing
culvert to provide a corresponding number of longitudinal cuts therethrough.
The number
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CA 02364666 2001-12-07
of cutters used will be determined by prior inspection and site conditions,
such as the
condition of the soil and of the culvert.
An example of the typical operation of the present invention may now be
illustrated with reference to the first embodiments of the cutter 40 and
spreader 30. Once
s one end of a culvert is located and, if need be, excavated to expose the
inlet, the cutter's
mouth is slid onto the culvert wall and is pushed on as far as it will go
until the cutting
wheels resist further movement. The pull string 20 should already be passed
through to
the other end of the culvert where the cutting is to finish, and the nose 42
of the cutter
should be attached to a coupling plate 24 and traveling link 26 of suitable
size for the
1o diameter of culvert to be cut. The number of cutters to be used is
determined based on
the earlier mentioned criteria. The spreader 30 is connected to the end of the
pull string
just behind the cutter, and the new culvert is in turn connected to the
spreader via the
collar 32. Force is then exerted on the far end of the pull string to draw the
cutter
longitudinally further onto the culvert wall. The cutting wheels 70 engage the
wall with
15 greater force and progressively push the wall toward the upper lip 46, and
in doing so the
wheels form a cut through the wall, thereby severing the culvert. The cone
head then
spreads the severed culvert and draws in the new culvert as is known in the
art. As the
cutter travels along the culvert, the lower lip 44 remains inside the culvert
while the upper
lip 46 remains outside the culvert. Hence, the frame's leading edge 58 pushes
aside the
2o ground and severs any external pipe obstructions that are encountered, such
as external
bolts.
An important advantage of the cutter 40 is its ability to cut through the
culvert
wall regardless of the culvert's structural integrity. The cutter does not
rely on structural
support from other portions of the culvert to counteract cutting forces.
Rather, the
25 upward forces of the cutting wheels 70 on the culvert wall are
counteracted, or resisted,
by the opposed upper lip 44 of the cutter's frame. Hence, all of the required
cutting
forces are offset "internally" within the cutter itself.
CA 02364666 2001-12-07
Another advantage of the present invention is the ability to use the same
cutter for
various sizes of culverts. As long as the thickness of the culvert wall can be
accommodated within the mouth 48 of the cutter, a user need only provide a
suitably
sized coupling plate 24 and/or travelling link 26 for the choosen culvert.
Hence, a user is
s able to avoid the needless cost of stocking various sizes of cutters and of
transporting
several sizes of cutters to a work site.
Yet another advantage is that the leading edge 58 is adapted to effectively
cut
through external culvert obstructions which traditionally have been
problematic for
conventional tools.
1o A further advantage is the ability to use more than one cutter during a
single pass
through an existing culvert to provide the desired number of longitudinal
cuts. Hence the
apparatus is easily and quickly adapted at a work site to the size and
integrity the
particular pipe, as well as the existing soil conditions.
The above description is intended in an illustrative rather than a restrictive
sense,
15 and variations to the specific configurations described may be apparent to
skilled persons
in adapting the present invention to other specific applications. Such
variations are
intended to form part of the present invention insofar as they are within the
spirit and
scope of the claims below. For instance, other variations in the number of
cutting wheels
(other than the sets of two or five described above) might be suitable for
certain soil
2o conditions. It should also be appreciated that the cutter may be used
individually without
the spreader in certain applications, such as for cutting a planar sheet of
metal for
instance.
16
