Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
SYNTHETIC FIBER CABLE
Technical Field
This invention relates to a synthetic fiber cable.
Background Art
Patent Document 1 describes the insertion of a
rod-shaped body, which is made of carbon fiber or
aramid fiber, into a concrete structure with the aim of
enhancing strength.
Prior-Art Documents:
Patent Documents:
Patent Document 1: Japanese Patent Application
Laid-Open No. 2000-110365
An oblong hole is drilled into a reinforced-
concrete pillar, and a rod-shaped body made of carbon
fiber is driven into the oblong hole. A gap remaining
in the oblong hole is subsequently filled with a
fluidized curable resin, thereby fixing the rod-shaped
body made of carbon fiber within the concrete. The
rod-shaped body made of carbon fiber is merely fixed
within the concrete by the fluidized curable resin that
contacts the surface of the rod.
Disclosure of the Invention
An object of the present invention is to provide a
synthetic fiber cable in which concrete or the like is
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allowed to penetrate the interior of a cable to thereby
enlarge the area of contact with the concrete or the
like, thereby making it possible to raise the
efficiency of fixation.
A further object of the present invention is to
provide a synthetic fiber cable that is excellent in
terms of handling, the cable flexing suitably when bent.
The synthetic fiber cable according to the present
invention is characterized by comprising: a core
member having multiple resin-impregnated synthetic
fibers, the fibers being bundled together; and multiple
side members each having multiple resin-impregnated
synthetic fibers, the fibers being bundled together in
each side member; wherein the resin is in a cured state
and each of the multiple side members has been shaped
utilizing curability of the resin; each of the shaped
multiple side members being in such a state that they
are twisted together around the core member.
By curing the resin, the core member and side
members formed by the multiple resin-impregnated
synthetic fibers maintain the shape that prevails when
the resin has cured. The resin will be cured by
heating if it is a thermosetting resin and by cooling
if it is a thermoplastic resin. If the resin is cured
in a state in which a prescribed shape has been
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imparted, the core and side members will be capable of
retaining this shape continuously thereafter.
The synthetic fibers that construct the core
member and side members (not natural fibers such as of
cotton or silk but fibers made from chemically
synthesized polymer) include carbon fiber, glass fiber,
boron fiber, aramid fiber, polyethylene fiber and PBO
(polyp-phenylenebenzobisoxazole) fiber, as well as
other fibers. These fibers are extremely slender and
can be impregnated with resin by bundling a number of
these synthetic fibers.
The synthetic fiber cable is constructed by
placing each of the multiple side members, which have
been shaped beforehand by utilizing the curability of
the above-mentioned resin, in a state in which they are
twisted together around the core member. In accordance
with the present invention, owing to the pre-shaping of
the side members utilizing the curability of the resin,
suitable spaces or gaps can be assured in the interior
of the synthetic fiber cable, specifically between the
core member and its surrounding side members as well as
between mutually adjacent side members, without
impairing the substantially twisted state of the side
members.
Owing to the fact that the core member and
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surrounding side members constituting the synthetic
fiber cable are in such a state that the resin has
cured on each member, slipping (shift in position) is
allowed between the core member and surrounding side
members as well as between mutually adjacent side
members. As a result, there is provided a synthetic
fiber cable which readily undergoes suitable flexing
when bending is applied, and which excels in handling
ease. For example, a synthetic fiber cable of great
length can be put into compact form by being wound upon
a small-diameter reel, thereby making handling easy at
the workplace. The synthetic fiber cable according to
the present invention is suitable for use as, for
example, an electrical transmission cable (power
transmission line), optical fiber cable, submarine
cable and other comparatively long members, and as
reinforcement for equipment.
In an embodiment, with regard to the core member
and each of the multiple side members, they have, along
the longitudinal direction thereof (there exist along
the longitudinal direction), both contact portions
where the side member is in contact with the core
member and non-contact portions where the side member
is not in contact with the core member. That is, the
multiple side members surrounding the core member are
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not in continuous contact with the core member along
their full length in the longitudinal direction but
rather have portions which are not in contact the core
member (portions where the side member is spaced away
from the core member). The synthetic fiber cable is
prevented from losing its shape owing to the contact
portions. Because the non-contact portions define
spaces between the core member and the side members,
they contribute to improved bending ease (pliability)
of the cable and are useful in facilitating the
penetration of concrete, mortar or other coagulants or
setting agents. For example, when the synthetic fiber
cable is embedded in concrete, the concrete will
penetrate into the interior of the synthetic fiber
cable and the cable will be fixed firmly inside the
concrete. The synthetic fiber cable according to the
present invention is suitable for use as reinforcement
for concrete structures, by way of example.
In another embodiment, with regard to each of the
multiple side members, each has, along the longitudinal
direction thereof, both contact portions in contact
with mutually adjacent side members and non-contact
portions not in contact with the mutually adjacent side
members. That is, the multiple side members
surrounding the core member are not in continuous
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contact with adjacent side members along their full
length in the longitudinal direction but rather have
portions which do not contact the adjacent side members
(there are gaps between the side members). The
synthetic fiber cable is prevented from losing its
shape owing to the contact portions. The non-contact
portions contribute to improved bending ease
(pliability) of the cable and are useful in
facilitating the penetration of concrete, mortar or
other coagulants or setting agents.
With regard to the contact portions and non-
contact portions between the core member and the side
members as well as the contact portions and non-contact
portions between mutually adjacent side members, it is
preferred that the contact portions and non-contact
portions be present repeatedly along the longitudinal
direction. Thus is provided a synthetic fiber cable
that is readily pliable along its full length. In a
case where this synthetic fiber cable is used in a
concrete structure, internal spaces that allow the
penetration of concrete can be assured in dispersed
fashion along the longitudinal direction of the
synthetic fiber cable, and entrances that allow the
penetration of concrete from the exterior to the
interior can be assured in dispersed fashion.
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Brief Description of the Drawings
Fig. 1 is a front view of a carbon fiber cable;
Fig. 2 is an exploded perspective view of the
carbon fiber cable;
Fig. 3 is an enlarged sectional view taken along
line III-III of Fig. 1;
Fig. 4 is an enlarged sectional view taken along
line IV-IV of Fig. 1;
Fig. 5 is an enlarged sectional view taken along
line V-V of Fig. 1; and
Fig. 6 is a graph illustrating results of a
concrete pull-out test.
Best Mode for Carrying Out the Invention
Fig. 1 illustrates the external appearance of a
carbon fiber cable. Fig. 2 is an exploded perspective
view of the carbon fiber cable. Figs. 3 to 5 are
enlarged sectional views of the carbon fiber cable
taken along lines III-III, IV-IV and V-V, respectively,
of Fig. 1.
A carbon fiber cable 1 is constituted by a single
core member 2 as well as six side members 3 (3a to 3f)
(a 1x7 structure) placed in such a state that the side
members are twisted together around the core member.
When viewed in cross section, the carbon fiber cable 1,
core member 2 and side members 3 all have a
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substantially circular shape. Further, when viewed in
cross section, the carbon fiber cable 1 is such that
the core member 2 is placed at the center thereof while
the six side members 3 are situated so as to surround
the core member 2. The carbon fiber cable 1 has a
diameter of 5 to 20 mm, by way of example.
The core member 2 and side members 3 each comprise
a large number, e.g., tens of thousands, of long carbon
fibers 4 impregnated with a thermosetting resin (epoxy
resin, for example) 5 and bundled into a shape having a
circular cross section. The overall carbon fiber cable
1 includes on the order of several hundred thousand of
the carbon fibers 4. Each of the carbon fibers 4 is
very slender and has a diameter of 5 to 7 pm, by way of
example. The core member 2 and side members 3 may each
be formed by bundling together the large number of
carbon fibers 4 impregnated with the thermosetting
resin 5 and twisting together a plurality of these
bundles of carbon fiber. The core member 2 and side
members 3 can also be referred to carbon fiber
reinforced plastics (CFRP).
In this embodiment, the core member 2 and side
members 3 employed have the same thickness (cross-
sectional area). The side members 3 used may of course
be thinner or thicker than the core member 2. The
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thickness of the core member 2 and of each of the side
members 3 can be adjusted at will depending upon the
number of carbon fibers 4.
The core member 2 and side members 3 constituting
the carbon fiber cable I are all used in a state in
which the thermosetting resin 5 has been heated and
cured in advance. Specifically, the carbon fiber cable
1 is produced by placing the side members 3, hardened
by utilizing the thermal curability of the
thermosetting resin 5, in such a state that they are
disposed and twisted together around the core member 2
which, similarly, has been hardened by utilizing the
thermal curability of the thermosetting resin 5. Since
the thermosetting resin 5 of the core member 2 and of
each of the side members 3 has cured, suitable slippage
is allowed between the core member 2 and surrounding
side members 3 and between the side members 3 that are
adjacent each other.
With reference to Fig. 2, the six side members 3
that will be placed in a state in which they are
twisted together around the core member 2 are all
shaped into a helical configuration beforehand; the
core member 2, on the other hand, does not undergo
helical shaping. It goes without saying that the side
members 3 are shaped into the helical configuration
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before the thermosetting resin 5 is thermally cured.
The pitch of the helix of each of the helically shaped
side members is substantially the same, and the inner
diameter of the helix of each of the side members 3 is
substantially equal to the diameter of the core member
2.
Each of the side members 3 partially has portions
(referred to as "bulged portions" below) shaped so as
to bulge slightly outward. Bulged portions 3A to 3D at
four locations are illustrated in somewhat emphasized
form on the carbon fiber cable 1 shown in Fig. 1.
Referring now to Fig. 3, when the portion having
the bulged portion 3A is viewed in cross section, it
will be seen that one side member (side member 3a)
among the six side members 3a to 3f around the core
member 2 is not in contact with the core member 2 but
is positionally displaced outwardly away from the core
member 2. The pre-shaping of the side member 3a is
carried out so as to give rise to this positional
displacement. Owing to the fact that the side member
3a is spaced away from the core member 2, an internal
space (non-contact portion) 11 is assured between the
core member 2 and side member 3a.
Since the core member 2 and side members 3 all
have a circular cross section, portions of non-contact
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inevitably exist between the core member 2 and side
members 3. [For example, in Fig. 3, an approximately
triangular space (indicated at reference numeral 20),
when viewed in cross section, is formed by the core
member 2, the side member 3c and the side member 3d].
However, the internal space 11 referred to in this
specification does not mean the space 20 having the
approximately triangular cross section but rather
signifies the space between the core member 2 and each
of the core members 3, this internal space being
assured by the pre-shaping of the core members 3. By
assuring the internal space 11, the two spaces 20
having the approximately triangular cross section are
connected.
In Fig. 3, the side member 3a situated between the
two side members 3b, 3f on either side is in contact
with the one side member 3f but is not in contact with
the other side member 3b and is positionally displaced
away from the side member 3b (shaping of the side
member 3a being performed in advance so as to give rise
to this positional displacement). A gap 12 is assured
between the side member 3a and the side member 3b owing
to the fact that the side member 3a is spaced away from
the side member 3b.
Referring now to Fig. 4, when a portion having the
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other bulged portion 3B is viewed in cross section, it
will be seen that two side members (side members 3e,
3f) among the six side members 3a to 3f around the core
member 2 are not in contact with the core member 2.
Instead, internal spaces 11 are assured between the
core member 2 and the side members 3e, 3f. Since the
side members 3e, 3f are adjacent each other, the two
internal spaces 11 are connected, resulting in the
formation of a large internal space. Further, although
the other side member 3c is in contact with the core
member 2, it is situated spaced away from both of the
two side members 3b, 3d situated on either side of the
side member 3c. Thus the gaps 12 are assured on both
sides of the side member 3c.
In Fig. 4, the internal spaces 11 are illustrated
as closed spaces. However, the internal spaces 11 are
not spaces completely cut off from the outside but
rather are open spaces in communication with the
outside. Specifically, the internal spaces 11 assured
between the core member 2 and side members 3 are
connected to the above-mentioned gaps 12 that are
assured by the fact that two mutually adjacent side
members are spaced away at other locations along the
longitudinal direction of the carbon fiber cable 1.
The internal spaces 11 are in communication with the
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outside through the gaps 12.
Referring now to Fig. 5, when the portion having
the bulged portions 30, 3D is viewed in cross section,
it will be seen that four side members (side members 3b,
3c, 3e, 3f) among the six side members 3a to 3f around
the core member 2 are not in contact with the core
member 2, thereby assuring internal spaces 11. Further,
gaps 12 are assured between side members 3a and 3b,
between side members 3c and 3d, between side members 3e
and 3f, and between side members 3f and 3a.
Thus, the carbon fiber cable 1 is such that the
locations and numbers of internal spaces 11 and gaps 12
differ depending upon the location where the cross
section is taken. Naturally, depending upon where the
cross section is taken, there will be instances where
the internal spaces 11 and gaps 12 do not appear at all
and, conversely, there can be instances where the six
side members 3 will not be in contact with the core
member 2 over its entire circumference. Further, as
illustrated in Figs. 3 to 5, the sizes of the internal
spaces 11 and gaps 12 (the distances between the core
member 2 and side members 3 and the distances between
mutually adjacent side members 3) that appear in a
cross section will vary. This means that the extent of
the multiple bulged portions 3A to 3D varies. It
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should be noted that extremely large bulged portions
(internal spaces 11 and gaps 12) do not exist in the
carbon fiber cable 1 and, hence, the essentially
twisted state is not impaired.
The bulged portions mentioned above are formed
repeatedly along the longitudinal direction of the
carbon fiber cable 1. That is, with regard to the core
member 2 and each of the multiple side members 3,
contact portions where the side members 3 are in
contact with the core member 2 (portions where the
internal spaces 11 do not exist) and non-contact
portions where the side members 3 are not in contact
with the core member 2 (portions where the internal
spaces 11 do exist) appear repeatedly along the
longitudinal direction. Similarly, with regard to side
members 3 that are adjacent each other, contact
portions (portions where the gaps 12 do not exist) and
non-contact portions (portions where the gaps 12 do
exist) appear repeatedly along the longitudinal
direction.
The bulged portion may be provided at prescribed
intervals, or provided randomly, on each side member
along the longitudinal direction thereof. Although the
bulged portion may be provided at identical intervals
on all of the side members 3 along the longitudinal
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direction thereof, the intervals of the bulged portions
along the longitudinal direction may be made different
for every side member 3. The bulged portions thus are
provided on the carbon fiber cable 1 in dispersed
fashion and the internal spaces 11 and gaps 12 along
the longitudinal direction of the carbon fiber cable 1
are present in dispersed fashion.
As set forth above, since the carbon fiber cable 1
is such that the thermosetting resin 5 on the core
member 2 and on each of the side members 3 has cured,
slippage is allowed between the core member 2 and side
members 3 and between side members 3 that are adjacent
each other. Furthermore, since the cable has the
internal spaces 11 and gaps 12, it undergoes suitable
flexing when bent and excels in handling ease. The
cable can be put into compact form by being wound upon
a small-diameter reel, thereby making handling easy at
the workplace. For example, the carbon fiber cable 1
is suitable for use as the core material of a long
object such as a power transmission line.
Further, the carbon fiber cable 1 can be used as
reinforcement for concrete structures, by way of
example. When the carbon fiber cable 1 is embedded in
concrete before the concrete sets (fresh concrete), the
concrete penetrates into interior of the carbon fiber
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cable 1 with the gaps 12 between mutually adjacent side
members 3 serving as entrances. Concrete that has
entered into the interior of the carbon fiber cable 1
from the gaps 12 enters the internal spaces 11 assured
between the core member 2 and side members 3, resulting
in greater area of contact between the carbon fiber
cable 1 and the concrete. Naturally, depending upon
such factors as the viscosity of the fresh concrete and
the sizes of the internal spaces 11 and gaps 12, the
concrete may not fill the internal spaces 11 completely.
However, in addition to the fact that the concrete
comes into contact with the outer periphery (surface)
of the carbon fiber cable 1, contact with the concrete
also occurs in the interior of the carbon fiber cable 1
as well. Hence an increase in the area of contact
between the concrete and the carbon fiber cable 1 is
achieved. As a consequence, adhesion stress can be
improved greatly in comparison with iron reinforcing
bars and the carbon fiber cable I can be fixed inside
the concrete with a high degree of fixing efficiency.
Concrete structures include bridge beams, piers, bridge
rails, protective barriers and the like.
Fig. 6 is a graph illustrating results of a
concrete pull-out test in which the horizontal axis is
a plot of slip displacement (mm) and the vertical axis
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a plot of adhesion stress (N/mm2). The solid line in
the graph indicates the result of testing the above-
described carbon fiber cable 1, and the broken line
indicates the result of testing a carbon fiber cable
that does not have the internal spaces 11 and gaps 12.
The diameters of the core members, side members, number
and structure thereof, as well as the length embedded
(the length fixed) in concrete were measured under
identical conditions.
The concrete pull-out test was conducted in line
with the "Method of Testing Adhesion Strength between
Continuous Fiber Reinforcing Material and Concrete by
Pull-out Test" of the Japan Society of Civil Engineers.
According to this test, a concrete block in which the
intermediate portion of a carbon fiber cable has been
embedded with both ends of the cable exposed to the
outside is fabricated. By using a tensile testing
machine, a tensile load is applied at a prescribed
loading rate to the carbon fiber cable projecting to
the outside from one end of the concrete block, and a
displacement gauge is used to measure the amount of
displacement (slip displacement) of the carbon fiber
cable projecting to the outside from the other end of
the concrete block.
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Adhesion stress T(N/mm2) was calculated using the
following equation:
Adhesion stress T = P/u.I.,
where P represents tensile load (kN), u the nominal
circumference (mm) of the carbon fiber cable and L the
adhesion length (mm) with respect to the concrete block.
As a result of the concrete pull-out test, it was
confirmed that, in comparison with the adhesion stress
(the broken line) of the carbon fiber cable devoid of
the internal spaces 11 and gaps 12, the adhesion stress
(the solid line) of the above-described carbon fiber
cable 1 is greatly improved and exhibits a high
concrete fixation efficiency.
The degree of shaping of the side members 3 (the
degree of constraint due to the side members 3) in the
carbon fiber cable 1 can be expressed by D/(a1+2a2) x
100(%) (referred to as "shaping ratio" below) using
diameter D of the cable 1 and diameters al and a2 of
the core member 2 and side members 3, respectively,
that constitute the cable 1. If the shaping ratio is
on the order of 100.1 to 105(%), the carbon fiber cable
1 will undergo suitable flexing when bent, and the
concrete adhesion efficiency will rise as well. In
cases where the emphasis is placed on concrete adhesion
efficiency and the concrete adhesion efficiency is to
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be raised, the multiple side members 3 may be shaped so
as to take on a shaping ratio on the order to 110%, by
way of example.
In the embodiment set forth above, an example is
described in which bundles of the multiple carbon
fibers 4 are impregnated with the thermosetting resin 5
and the carbon fiber cable 1 is constructed from the
core member 2 and side members 3 hardened by applying
heat to the thermosetting resin 5. However, a
thermoplastic resin (polyamide, for example) may used
instead of the thermosetting resin 5. Further, instead
of carbon fiber, glass fiber, boron fiber, aramid fiber,
polyethylene fiber and PBO (polyp-
phenylenebenzobisoxazole) fiber, as well as other
synthetic fibers, can be used.
[Description of Symbols]
1: carbon fiber cable
2: core member
3, 3a, 3b, 3c, 3d, 3e, 3f: side members
3A, 3B, 3C, 3D: bulged portion
4: carbon fiber
5: thermosetting resin
11: internal space
12: gap
