Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
SPARK CAPTURE SYSTEM FOR USE WITH CUTTING TORCH
Cross-Reference to Related Applications
[0001] This application claims priority from U.S. provisional application
number
62/485,483, filed April 14, 2017.
Technical Field/Field of the Disclosure
[0002] The present disclosure relates generally to an apparatus and method for
containing
sparks emitted during a cable cutting process. More particularly, the present
disclosure relates
to a spark capture system for use with a cutting torch.
Background of the Disclosure
[0003] Cutting torches are frequently used to cut metal, including metal
cables. Some of the
applications in which it may be desired to cut metal include, but are not
limited to, concrete
members that may include tensioning strands, rebar, or the like.
[0004] Many structures are built using concrete, including, for instance,
buildings, parking
structures, apaitments, condominiums, hotels, mixed-use structures, casinos,
hospitals,
medical buildings, government buildings, research/academic institutions,
industrial buildings,
malls, bridges, pavement, tanks, reservoirs, silos, foundations, sports
courts, and other
structures.
[0005] Prestressed concrete is structural concrete in which internal stresses
are introduced to
reduce potential tensile stresses in the concrete resulting from applied
loads; prestressing may
be accomplished by post-tensioned prestressing. In post-tensioned
prestressing, a tension
member is tensioned after the concrete has attained a specified strength by
use of a post-
tensioning tendon. The post-tensioning tendon may include anchors, the tension
member, and
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sheathes or ducts. A tension member is conventionally constructed of a
material having
sufficient tensile strength that can also be elongated. Tension members are
conventionally
formed from a strand and a sheath. The strand is conventionally formed as a
single or multi-
strand metal cable. The strand is conventionally encapsulated within a
polymeric sheath
extruded thereabout to, for example, prevent or retard corrosion of the metal
strand by
protecting the metal strand from exposure to corrosive or reactive fluids.
Likewise, the sheath
may prevent or retard concrete from bonding to the strand and preventing or
restricting
movement of the sheath during post-tensioning. The sheath may be filled with
grease to
further limit the exposure of the metal strand and allow for increased
mobility. The post-
tensioning tendon conventionally includes an anchorage at each end. The
tension member is
fixedly coupled to a fixed anchorage positioned at one end of the post-
tensioning tendon, the
so-called "fixed-end", and stressed at the other anchor, the "stressing-end"
of the post-
tensioning tendon.
[0006] The concrete may be poured into a concrete form. The concrete form may
be a form or
mold into which concrete is poured or otherwise introduced to give shape to
the concrete as it
sets or hardens thus forming the concrete member. The post-tensioning tendon
may be
positioned within the concrete form, the concrete poured, and the concrete
member then
stressed to form a concrete segment. After the concrete member is stressed,
the tension
member extends beyond the edge of the concrete segment. In some cases, a
pocket former is
placed around the strand before the concrete is poured, which results in a
pocket in the cured
concrete. The end of the strand extends outwardly from the concrete and, if a
pocket former
was used, the end of the strand extends through and outwardly from the pocket.
Conventionally, at least a portion of the strand that extends beyond the edge
of the concrete
member is cut, such as by a cutting torch. If a pocket former was used, the
cutting of the
strand may take place in the pocket.
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[0007] Cutting torches generate sparks during the process of cutting the
strand. Sparks
generated by cutting torches may cause fires in nearby flammable materials.
Such fires may
result in damage, danger to personnel, delays, and increased monitoring costs.
Summary
[0008] A spark absorbing system for use with a cutting torch may comprise a
cap having at
least one spark opening therethrough and a spark capture unit. The spark
capture unit may be
coupled to the cap and positioned to capture sparks passing through the spark
opening. The
spark capture unit may comprise a tube extending from the cap. The spark
capture unit
includes an outlet and may include a flow-reduction element positioned between
the cap and
the outlet. The flow-reduction element may comprise at least one baffle,
screen or mesh. The
spark absorbing system may further include a spark accumulator between the cap
and the
spark capture unit, a spark ramp extending from the cap opposite the spark
capture unit, and/or
a shield and generally parallel to the cap so as to define a cutting space
between the shield and
the cap.
[0009] The cap may comprise one or more layers of mesh screens, which may be
generally
parallel.
[0009a] In some embodiments, a method may comprise: supplying a concrete
segment, the
concrete segment having an end, wherein the concrete segment end includes a
pocket;
extending a strand from the concrete segment, wherein the strand extends
outwardly through
the pocket; and providing a cutting torch having a cutting head. The method
further comprises
providing a spark absorbing system, the spark absorbing system comprising: a
cap, wherein
the cap encloses the pocket and includes a spark opening; and a spark capture
unit, the spark
capture unit attached to or formed integrally with the cap, wherein the spark
capture unit is
configured to capture sparks that pass through the spark opening. The method
further
comprises: placing the cutting head and the spark absorbing system at the
strand; operating the
cutting torch; and capturing or deflecting sparks generated from the cutting
torch using the
spark absorbing system.
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Date Recue/Date Received 2021-09-22
[0010] In some embodiments, a system for cutting a strand in a concrete
segment having an
end, a pocket at the end, and a strand extending from the pocket may include a
cutting torch
including a cutting head and a spark absorbing system supported on the cutting
torch. The
spark absorbing system may comprise a cap having at least one spark opening
therethrough
and a spark capture unit that may be coupled to the cap and positioned to
capture sparks
passing through the spark opening. The spark capture unit may be a tube
extending from the
cap. The spark capture unit may include an outlet and a flow-reduction element
positioned
between the cap and the outlet and the flow-reduction element may include at
least one baffle,
screen or mesh.
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[0011] The spark absorbing system may further include a spark accumulator
between the cap
and the spark capture unit, a spark ramp extending from the cap opposite the
spark capture
unit and positioned to receive sparks emitted at the cutting head, and a
shield coupled to the
spark ramp and generally parallel to the cap so as to define a cutting space
between the shield
and the cap, with the cutting head in the cutting space.
[0012] In some embodiments, a process may include the steps of supplying a
concrete
segment, the concrete segment having an end, the concrete segment having a
pocket at the
end; extending a strand through the pocket; providing a cutting torch having a
cutting head
and a spark absorbing system coupled thereto, the spark absorbing system
comprising a cap
having at least one spark opening therethrough and a spark capture unit
coupled to the cap and
positioned to capture sparks passing through the spark opening; placing the
cutting head in the
pocket; operating the cutting torch; and capturing or deflecting sparks
generated from the
cutting torch using the spark absorbing system. In some embodiments, the cap
may enclose
the pocket and the spark absorbing system may extend outwardly therefrom.
Brief Description of the Drawings
[0013] The present disclosure is best understood from the following detailed
description when
read with the accompanying figures. It is emphasized that, in accordance with
the standard
practice in the industry, various features are not drawn to scale. In fact,
the dimensions of the
various features may be arbitrarily increased or reduced for clarity of
discussion.
[0014] FIG. 1 is a detailed view of a prior art cutting torch.
[0015] FIG. 2 is a cross-sectional view of a cutting torch with a spark
absorbing unit
consistent with certain embodiments of the present disclosure received in a
pocket in a
concrete member.
[0016] FIGS. 3 and 4 are orthographic views of the cutting torch and spark
absorbing unit of
FIG. 2.
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[0017] FIGS. 5-7 are each a cross-sectional view of a portion of a spark
absorbing unit
consistent with certain embodiments of the present disclosure.
Detailed Description
[0018] It is to be understood that the following disclosure provides many
different
embodiments, or examples, for implementing different features of various
embodiments.
Specific examples of components and arrangements are described below to
simplify the
present disclosure. These are, of course, merely examples and are not intended
to be limiting.
In addition, the present disclosure may repeat reference numerals or letters
in the various
examples. This repetition is for the purpose of simplicity and clarity and
does not in itself
dictate a relationship between the various embodiments or configurations
discussed.
[0019] "Coupled" for purposes of this disclosure, may include any form of
coupling, including
but not limited to "mechanical coupling." "Mechanically coupled" for purposes
of this
disclosure, may include, but not be limited to, threaded couplings, press
fitting, mechanical
welding, chemical welding, friction welding, thermal coupling or welding,
electrical welding,
optical welding, or beam-energy welding.
[0020] As depicted in FIG. 1, a cutting torch 20 may be used for a cutting
strand 16. In
certain embodiments, cutting torch 20 may be a plasma cutting torch or may use
a gas source,
such as a source of air, nitrogen, argon or oxygen, and an electrical power
source and
electrodes to generate a stream of air, nitrogen or other gaseous at
temperatures sufficient to
cut strand 16, for example and without limitation, from about 3,000 C - 5,000
C or more.
[0021] While the present disclosure is presented in the context of use with a
cutting torch, it
will be understood that the spark absorbing systems described herein can be
used
advantageously with any strand-cutting device that generates sparks, including
but not limited
to oxy-cutting torches fueled with acetylene, propane, or stabilized mixtures
of
methylacetylene (propyne) and propadiene.
Date Recue/Date Received 2021-09-22
[0022] Cutting torch 20 may include a handle 22, a head 24, and a cutting tip
26. A heat shield
25 may surround at least a portion of cutting tip 26. Heat shield 25 may be
formed of, for
example, ceramic. Cutting torch 20 may also include a compressor, cylinder or
other source
(not shown) for the gas to be formed into the plasma, a source of electrical
power (not shown)
and an electrode (not shown) for converting the gas into a gaseous plasma. The
electrode may
be disposed in handle 22, head 24, or in another portion of cutting torch 20.
In certain
embodiments, cutting torch 20 may include an electrical ground. The electrical
ground may
include, but not be limited to a metal or other conductive element that
touches strand 16. In
other embodiments, the ground may be clamp 28, as described hereinbelow. A
superheated
stream of gaseous plasma is discharged from cutting tip 26. During cutting,
cutting tip 26 is
positioned near strand 16.
[0023] Clamp 28 may be releasably coupled to strand 16, such as through
bracket 30. Bracket
30 may be coupled to head 24 of cutting torch 20. Bracket 30 may be sized to
be friction fitted
around head 24 or may be permanently attached to head 24 or heat shield 25. In
some
embodiments, positioners may be attached to bracket 30 so as to position
cutting tip 26 at a
predetermined distance from anchor 14 along the longitudinal axis of strand
16. In certain
embodiments, the positioners may be a pair of depending jaws 32, 34. In some
embodiments,
depending jaws 32, 34 may be pivotally attached to bracket 30 and may be
biased towards a
closed position by a biasing mechanism 36, such as a spring clip. Each of
depending jaws 32,
34 may include a semicircular relieved portion 38 on its inner edge. When
depending jaws 32,
34 are closed, jaws 32 may abut jaw 34 and semicircular relieved portions 38
may form a
circular opening through which the strand 16 may be received. The bottom
portion of each
depending jaw 32, 34 may include a sloping area 41. Sloping area 41 may serve
to force jaws
32, 34 apart when jaws 32, 34 are pushed against tension a strand 16. Once
strand 16 is
received within the circular opening, depending jaws 32, 34 may close around
strand 16.
[0024] When cutting torch 20 is to be used, jaws 32, 34 may be positioned
around the strand
16. Jaws 32, 34 may be biased into a closed position by biasing mechanism 36.
Jaws 32, 34,
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with head 24 attached pivotally thereto by the bracket 30, may be moved
longitudinally along
strand 16 until depending jaws 32, 34 are in position. Cutting tip 26 may then
be positioned
both angularly and longitudinally about strand 16 and anchor 14 for cutting
the strand 16.
[0025] In certain embodiments, strand 16 may be encased by a sheath. As
depicted in FIG. 1,
the sheath has been removed prior to placement of clamp 28. In other
embodiments, clamp 28
may be placed over the sheath.
[0026] Referring now to FIG. 2, a concrete segment 10 may be part of a
concrete member that
is to be post-tensioned. Concrete segment may or may not include a pocket 12,
which may be
formed in the end of concrete segment 10. An anchor 14 may be positioned about
strand 16.
Strand 16 may be held in place by wedges 18 seated within anchor 14. A
tensioning end 16'
of strand 16 may extend through pocket 12, if present, and outwardly from
concrete segment
10.
[0027] A cutting torch 20 is shown in pocket 12. Elements of the cutting torch
20 may be
located within pocket 12, including, but not limited to, head 24, clamp 28,
heat shield 25, and
cutting tip 26. A gas supply 80 is depicted as outside pocket 12. As shown in
FIG. 2, a spark
absorbing system 40 may be included with, coupled to, and/or supported by or
on cutting torch
20 and portions thereof may also be received within pocket 12.
[0028] Referring now to FIGS. 3 and 4, in the embodiment shown, spark
absorbing system 40
may include a cap 42, a strand ground shroud 52, a spark ramp 54, a spark
accumulator 56,
and a spark capture unit 44.
[0029] In the embodiment of FIGS. 3 and 4, clamp 28 is replaced with a shield
58. Shield 58
is optional and may be omitted or replaced with a clamp 28 or other member.
Shield 58 may
be a single flat piece having a size and shape corresponding generally to the
size and shape of
the inner face of concrete pocket 12. In some embodiments, a notch 59 is
provided in shield
58 to facilitate installation of spark absorbing system 40 onto the strand end
16'. Shield 58
may be generally parallel to cap 42 so that a cutting space is defined between
the shield 58 and
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the cap 42. In some embodiments, the shape of shield 58 may correspond to the
shape of
pocket 12 and if the anchor is encapsulated in a polymeric encapsulation
layer, shield 58 may
prevent sparks from reaching the anchor encapsulation layer.
[0030] Cap 42 is optional. Cap 42 may be a barrier, such as a plate or may
have a curved or
enclosing surface. Cap 42 may be positioned at least partially and, in some
embodiments,
completely within pocket 12, or may extend across the opening of pocket 12 and
abut the
outer surface of the concrete that forms pocket 12. In some embodiments, cap
42 encloses
pocket 12 such that a chamber 13 is defined generally by cap 42, the walls of
pocket 12, and
either the floor of pocket 12 or, if present, shield 58. Cap 42 may be
constructed of metal,
ceramic, or heat-resistant plastic, for example, and may include spark opening
43 and handle
aperture 46 therethrough. Handle aperture 46 may be adapted to allow handle 22
to pass
through cap 42. Thus, cap 42 may engage or be coupled to and/or supported by
or on cutting
torch 20. If a spark ramp 54 is present, cap 42 may also or alternatively be
coupled to and/or
supported by or on spark ramp 54. Cap 42 may be formed from one, two, or more
solid
pieces, as shown, may be formed from mesh as described below, or may comprise
any other
structure that reduces the outward flow of sparks. In embodiments where the
concrete
member does not include a pocket, either shield 58 or cap 42 may optionally
extend fully or
partially around the sides of the cutting torch head.
[0031] Strand ground shroud 52 is optional. Strand ground shroud 52 forms a
grounded
electrical (conducting) contact between strand end 16' and a ground. The
ground may be
provided via the concrete, via the electrical systems of cutting torch 20, via
a dedicated
electrical conductor in contact with the earth, or by any other suitable
ground.
[0032] Spark ramp 54 is optional. If present, spark ramp 54 may be a channel-
shaped piece
that extends between the shield 58 and the cap 42, on the opposite side of
strand 16 from torch
cutting tip 26. In this location, spark ramp 54 is configured to divert gas
and sparks emitted
during the cutting process and direct the sparks toward spark opening 43,
through which the
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sparks may enter spark capture unit 44. If spark ramp 54 is omitted, the inner
wall of concrete
pocket 12 may serve the same purpose.
[0033] Spark accumulator 56 is optional. If present, spark accumulator 56 may
be a chamber
adjacent to spark opening 43 positioned such that sparks passing through spark
opening 43
enter spark accumulator 56. In some embodiments, the volume of spark
accumulator 56
relative to the size of spark opening 43 may cause the velocity of gas flowing
through spark
absorbing system 40 to drop, causing particles entrained in the gas flow to
fall out and collect
on the floor of spark accumulator 56.
[0034] Spark capture unit 44 may include an arrester tube 49 that is connected
at one end to
spark accumulator 56 and has at its opposite end one or more outlets 50 that
may each
optionally be enclosed by a mesh screen 48. Spark capture unit 44 may serve to
capture
and/or deflect sparks, preventing or restricting sparks from exiting pocket 12
through outlets
50. Spark capture unit 44 may allow gas from gas source 80 to pass through
outlets 50. In
certain embodiments, spark capture unit 44 may be a generally cylindrical or
polygonal
extension from cap 42. Spark capture unit 44 may be releasably attached to or
integrally
formed with cap 42 or may be releasably attached to or integrally formed with
cutting torch
20.
[0035] In some embodiments, arrester tube 49 may comprise a hollow tube. In
other
embodiments, arrester tube 49 may contain one or more flow-reduction elements,
including
but not limited to the exemplary flow-reduction elements illustrated in FIGS.
5-7. In the
embodiment shown in FIG. 5, the flow-reduction element of spark capture unit
44 may include
one or more baffles 60. In the embodiment shown in FIG. 6, the flow-reduction
element of
spark capture unit 44 may include one or more mesh screens 62. In the
embodiment shown in
FIG. 7, the flow-reduction element of spark capture unit 44 may include one or
more cylinders
70. When spark capture unit 44 includes more than one cylinder 70, cylinders
70 may be
nested. In some embodiments, one or more of cylinders 70 may include mesh 72.
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[0036] In still other embodiments, the cap 42 itself may include one or more
mesh screens and
may, in some embodiments, omit any or all of spark ramp 54, spark accumulator
56 and spark
capture unit 44. Cap 42 acts to capture and/or deflect sparks, preventing or
restricting sparks
from passing through cap 42. In certain embodiments, cap 42 may comprise a
plurality of
layered mesh screens.
[0037] The foregoing outlines features of several embodiments so that a person
of ordinary
skill in the art may better understand the aspects of the present disclosure.
Such features may
be replaced by any one of numerous equivalent alternatives, only some of which
are disclosed
herein. One of ordinary skill in the art should appreciate that they may
readily use the present
disclosure as a basis for designing or modifying other processes and
structures for carrying out
the same purposes and/or achieving the same advantages of the embodiments
introduced
herein. One of ordinary skill in the art should also realize that such
equivalent constructions do
not depart from the spirit and scope of the present disclosure and that they
may make various
changes, substitutions, and alterations herein without departing from the
spirit and scope of the
present disclosure.
Date Recue/Date Received 2021-09-22
