Note: Descriptions are shown in the official language in which they were submitted.
CA 02669265 2009-05-06
Description
Title
FISH PRESERVE, AND FISH PRESERVE MANUFACTURING METHOD
Field
[0001]
The present invention relates to a fish preserve or crawl and a manufacturing
method of the same.
Background
[0002]
As this kind of technology, patent document 1 discloses a crawl including a
net
which is immersed in and brought into contact with seawater during use for,
for
example, fish cultivation and the like in the sea. The net of the crawl is,
for example,
so-called diamond-shaped wire netting (wire netting that wires, each which is
bent in a
chevron shape at a fixed pitch with a jig, are continuously intertwined with
each other
and woven so that each stitch is in a diamond shape) shown in Figs. 1, 3 and 4
of
patent document 1. Additionally, as the net of the crawl, a net is employed
that wires
constituting the net are woven in accordance with a uniform manufacturing of
the net.
Accordingly, the net for crawls has directionality that the wires constituting
the net are
subjected to the fixed uniformity.
Citation List
Patent Literature
[0003]
patent document 1: JP2001-190178A (Paragraph No. 1, Figs. 1, 3 and 4)
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Summary
Technical Problem
[0004]
As described above, a net constituting a crawl has some kind of
directionality.
The size of the crawl, which has been conventionally used for fish cultivation
and the
like, is, at most, 50m (the length of an outer peripheral part of an upper end
of a side
net) x6 to 15m (depth). Therefore, weight applied to the whole of the crawl is
small,
and load applied to wires is not so large. Accordingly, the net may be
constituted
independently of directionality. In terms of ease in construction, a method
has been
widely employed that is called lateral net, in which wires of the side net
extend parallel
to the sea surface.
In the case of upsizing the crawl, its own weight thereof sometimes becomes
several times as large as that of a conventional crawl. Additionally, under an
environment of fish cultivation and the like in the sea, it is impossible to
avoid
influence of factors such as tides, wave heights and the like. That is,
upsizing the
crawl forces a large load on the wires. Further, in a material which forms the
wire,
generally, a lateral modulus (shearing modulus) is smaller than a longitudinal
modulus
(Young's modulus), and shearing stress is smaller than tensile stress. That is
why the
crawl constituted by the lateral net is likely to be deformed or broken since
its own
weight is applied, as load, to an intertwined part of the wires of the side
net in a
shearing direction. Additionally, the crawl is likely to be deformed or broken
due to
increased load applied to the wires in a fixed part that the side net is
arbitrarily tied in
being attached to a frame body. Furthermore, there remains a problem that a
broken
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opening part is enlarged by its own weight.
Additionally, in the case of the lateral net of the diamond-shaped wire
netting,
wires of the side net continuously intertwined are parallel to the sea
surface, and
intertwining of the wires has no restriction force. Accordingly, when an
external
force is applied to the side net in a horizontal direction or a bottom net
side direction
due to influence of tides and the like, the crawl is likely to be deformed.
Additionally,
there remains a problem that the volume of the crawl decreases.
[0005]
The present invention was made in order to solve the above problems, and it is
a first object of the present invention to provide a crawl designed so as to
suppress to a
minimum the risk that its own weight has, and further provide a crawl that
further
enlargement of an opening part caused by breakage can be controlled even when
a part
of the net is broken by a certain factor. Further, it is a second object to
provide a
crawl where the cost of materials to the volume of the crawl can be reduced by
upsizing the crawl. Furthermore, it is a third object to provide a crawl where
the
reduction in the volume during use is suppressed to a minimum compared with
the
volume secured in a stationary state.
Solution to Problem
[0006]
Problems to be solved by the present invention are as described above, and
next, means for solving the problems and effects of the means will be
described below.
[0007]
According to a first aspect of the present invention, there is provided a
crawl
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constituted as follows. That is, the crawl includes a bottom net, a side net
which is
peripherally provided on the bottom net, and a frame body which is arranged
along the
sea surface and to which an upper end of the side net is fastened. The side
net is
constituted in a manner that wires formed by bending and forming metallic
wires each
into a predetermined shape are arranged in a row and interlocked with each
other.
Additionally, the side net is attached to the bottom net and the frame body so
that the
plurality of row wires vertically extend when the crawl is in use. According
to this
constitution, even if any of the plurality of row wires constituting the side
net is broken,
further enlargement of an opening caused by the breakage can be controlled by
other
wires adjacent to the broken wire. In the crawl, since the plurality of row
wires of the
side net vertically extend, load is applied to the wires in a wire axis
direction. In a
material which forms the wire, generally, a longitudinal modulus (Young's
modulus) is
larger than a lateral modulus (shearing modulus), and tensile stress is larger
than
shearing stress. Thus, the risk that its own weight has with regard to
breakage or
deformation of the crawl, can be controlled, and the crawl can be upsized at
minimal
risk. Since the plurality of row wires of the side net vertically extend, the
crawl
attempts to remain at the original position in accordance with bend-rigidity
that the
plurality of row wires have and its own weight, in the case where an external
force
generated by tides or the like parallel to the sea surface is applied to the
side net.
Thus, the crawl has an excellent shape retaining property. Further, in the
crawl, since
the row wires of the side net vertically extend, they receive compression
force in the
case where an external force generated by pushing-up of seawater from the
bottom net
side is applied to the side net. That is, resistance force of the row wires
against the
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compression force makes the crawl retain its shape, and thus the crawl has an
excellent
shape retaining property.
[0008]
Preferably, the crawl is constituted as follows. That is, the side net is
peripherally provided on the bottom net via a coil-shaped connecting member,
and the
side net, the bottom net and the connecting member are composed of the same
metallic
material. According to this constitution, galvanic corrosion between the
bottom net
or the side net and the connecting member can be avoided, and the side net can
be
easily connected to the bottom net.
[0009]
Preferably, the crawl is constituted as follows. That is, the bottom net and
the
side net are composed of copper or a copper alloy. According to the material,
a crawl
can be obtained that a stain-proof effect and a weed-proof effect are exerted
by
oligodynamie.
[0010]
Preferably, the crawl is constituted as follows. That is, the upper end of the
side net is fastened to the frame body via an insulating member. According to
this
constitution, even if the frame body is composed of a material different from
that of the
side net, the galvanic corrosion between the side net and the frame body can
be
securely avoided, and thus the material of the frame body can be freely
selected.
[0011]
Preferably, the crawl is constituted as follows. That is, the length of the
outer
peripheral part of the upper end of the side net attached to the frame body is
50m or
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more. Various advantages are obtained by upsizing the crawl. For example, (1)
in
the case of a general crawl with a size of I Omx l Omx8m, the surface area for
use is
420m2, and the volume for use is 800m3; and, (2) in the case of a crawl with a
size of
24mx24mx l Om, the surface area for use is 1536m2, and the volume for use is
5760m3.
The rates of the use area to the volume in the crawl are 1.90m3/m2 in (1), and
3.75m3/m2 in (2). That is, this results in a savings cost of materials to be
used for the
unit volume of the crawl. If the volume of the crawl is increased by upsizing
the
crawl, the number of contacts between fish or contacts of fish and the net is
reduced,
and stress of the fish can be reduced, in the case of, for example, fish
cultivation and
the like. Thus, a more excellent cultivation environment can be provided.
[0012]
Preferably, the crawl is constituted as follows. That is, a fastening wire
used
in attaching the side net to the frame body is provided by at least two meshes
of the net.
According to this constitution, its net's own weight can be prevented from
deforming
the upper part of the net. Additionally, load to be applied to the net and
fatigue of the
net are reduced, and endurance thereof can be improved.
[0013]
According to a second aspect of the present invention, there is provided a
manufacturing method of the crawl including a bottom net, a side net which is
peripherally provided on the bottom net, and the frame body which is arranged
along
the sea surface and to which the upper end of the side net is fastened,
including the
steps of: annularly connecting the side net to a peripheral edge of the bottom
net which
is in a state of being developed on an inner peripheral side of the frame body
so as to
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be flush with the frame body; and, bending the side net in a direction
orthogonal to an
inner peripheral edge of the frame body so that the upper end of the side net
is arranged
along the inner peripheral edge of the frame body. According to this method,
the side
net is connected to the frame body and the bottom net with the frame body and
the
bottom net flush with each other.
[0014]
Preferably, the manufacturing method is as follows. That is, the method
further includes the step of fastening the upper end of the side net to the
frame body
before releasing a state where the bottom net is flush with the frame body.
According
to this method, the side net is developed by action of its own weight of the
bottom net
only by releasing the state where the bottom net is flush with the frame body.
[0015]
Preferably, the manufacturing method of the crawl is as follows. That is, the
method further includes the step of laying a surface member to be flush with
the frame
body on the inner peripheral side of the frame body. According to this method,
the
bottom net can be developed on the inner peripheral side of the frame body so
as to be
flush with the frame body regardless of an environment of a manufacturing site
of the
crawl. That is, the manufacturing site of the crawl can be placed on the sea.
[0016]
Preferably, the step above is as follows. That is, a plurality of wire rods
are
arranged and laid on the inner peripheral side of the frame body, and then, a
plurality
of other wire rods are arranged and laid on the inner peripheral side of the
frame body
so as to be orthogonal to the plurality of wire rods. According to this step,
the surface
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member is strengthened, and thus the state can be securely kept where the
bottom net is
flush with the frame body when the bottom net is developed on the surface
member,
and other wire rods serve as a guiding mechanism for developing the bottom
net.
[0017]
Preferably, the manufacturing method is as follows. That is, the method
further includes the step of providing a floating member having a floating
property for
seawater under the surface member. According to this method, the state can be
more
securely kept where the bottom net is flush with the frame body.
Brief Description of Drawings
[0018]
Fig. 1 is a perspective view showing a set-up state of a crawl according to an
embodiment of the present invention.
Fig. 2 is a partial enlarged view of Fig. 1.
Fig. 3 is a view similar to Fig. 2.
Fig. 4 is a view showing a part of a connection state of a bottom net and a
side
net.
Fig. 5 is a cross sectional view taken along line A-A in Fig. 1 and viewed in
an
arrow direction.
Fig. 6 is a view showing a state where an upper end 2a of a side net 2 is
fastened to a pipe member 3c of a frame body 3 via a fastening wire rod 6.
Fig. 7 is a perspective view of the crawl according to the embodiment of the
present invention, and a view showing a first step of a manufacturing method
of the
crawl.
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Fig. 8 is a view showing a part of a second step of the manufacturing method
of the crawl, and is similar to Fig. 7.
Fig. 9 is a view showing a part of the second step of the manufacturing method
of the crawl, and is similar to Fig. 7.
Fig. 10 is a view showing a part of a third step of the manufacturing method
of
the crawl, and is similar to Fig. 7.
Fig. 11 is a view showing a part of a fourth step of the manufacturing method
of the crawl, and is similar to Fig. 7.
Fig. 12 is a view showing a part of the fourth step of the manufacturing
method of the crawl, and is similar to Fig. 7.
Reference Signs List
[0019]
1 bottom net
2 side net
2a upper end
2b lower end
3 frame body
4 connecting member
insulating member
a row wires
Description of Embodiments
[0020]
Herein, "flush with" means "on the same surface." For example, "B member
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flush with A member" indicates "B member on a surface the same as a surface
which
can be directly conceived based on A member."
[0021]
An embodiment of the present invention will be described hereinafter. Fig. 1
is a perspective view showing a set-up state of a crawl according to the
embodiment of
the present invention.
[0022]
<Summary of Crawl 100>
As shown in Fig. 1, in terms of productivity, the crawls 100 of the embodiment
are set up in the sea. The crawl 100 includes a bottom net 1, a side net 2
which is
peripherally provided on the bottom net 1, and a frame body 3 which is
arranged along
the sea surface and to which an upper end 2a of the side net 2 is fastened.
Additionally, a box type (rectangular parallelepiped-shaped) housing space is
formed
by the bottom net 1 and the hanging side net 2, and fish and the like of a
predetermined
amount are housed in the housing space. Additionally, the housing space is
kept at a
fixed distance from the sea surface by adding a floating property to seawater
to the
frame body 3.
[0023]
<Side net 2>
Fig. 2 is a partial enlarged view of Fig. 1. As shown in Fig. 2, the side net
2
is constituted by a plurality of row wires a which are bent and formed each
into a
predetermined shape, arranged in a row, and interlocked with each other. That
is, the
side net 2 is a net constituted in a manner that the wires (row wires a), each
which is
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bent in a chevron shape at a predetermined pitch with a jig, are continuously
intertwined with each other and woven so that each stitch is in a diamond
shape. As a
matter of fact, the side net 2 is classified as so-called diamond-shaped wire
netting.
[0024]
A diameter d of the row wire a is 2.0 to 5.0mm, and a material of the wire is
copper or a copper alloy in the embodiment. Compositions of the copper alloy
are
indicated below.
[0025]
Cu [Wt%]: 62.0 - 69.0
Sn [Wt%]: 0.2 - 1.0
Ni [Wt%]: 0.1 - 1.0
=The remaining, Zn [Wt%]: 29.0 - 37.7 (containing unavoidable impurities)
[0026]
Here, reference is made to Fig. 3, as shown in the figure, a lower end 2b of
the
side net 2 is subjected to double knuckle type processing that the row wire a
is bent at
approximately 180 and fastened to the adjacent row wire so as to be
intertwined
therewith. An upper end 2a of the side net 2 is similarly subjected to the
double
knuckle type processing (see Fig. 1).
[0027]
Additionally, as shown in Fig. 2, the side net 2 is attached to the bottom net
1
and the frame body 3 so that the row wires a vertically extend when the crawl
100 is in
use.
[0028]
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<Bottom net 1>
The bottom net 1 of the embodiment is, similar to the side net 2, classified
into
so-called diamond-shaped wire netting. Processing of an end of the bottom net
1, and
the diameter d and the material of the row wire a of the net 1 are similar to
those of the
side net 2.
[0029]
<Connection of Bottom net 1 and Side net 2>
As described above, the side net 2 is peripherally provided on the bottom net
1
(see Fig. 1). Fig. 4 is a view showing a part of a connection state of the
bottom net
and the side net.
[0030]
As shown in Fig. 4, the side net 2 is connected to the bottom net 1 via a
connecting member 4 formed in a coil shape. That is, the coil-shaped
connecting
member 4 alternatively (mesh by mesh) passes through a stitch of the side net
2 and a
stitch of the bottom net 1, and thus the side net 2 is connected to the bottom
net 1.
Additionally, the side net 2, the bottom net 1 and the connecting member 4 are
composed of the same metallic material (copper or a copper alloy in the
embodiment).
Moreover, the connecting member 4 may be coiled smoothly with no corner or
coiled
with a corner.
[0031]
<Frame body 3>
Next, the frame body 3 will be described with reference to Fig. 1. As
described above, the floating property for seawater is added to the frame body
3.
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Specifically, a plurality of floats (not shown) are provided on the frame body
3, the
floats float on the seawater so that the frame body 3 has the floating
property for
seawater, and therefore the frame body 3 is arranged along the sea surface. In
the
embodiment, a material of the frame body 3 is iron or an iron alloy, and the
size of the
frame body is 24[m] square.
[0032]
The frame body 3 has various functions as follows: a first function of, as
described above, keeping the distance constantly from the sea surface to the
housing
space while the upper end 2a of the side net 2 is fastened to the frame body,
the
housing space being formed by the side net 2 and the bottom net 1; a second
function
of keeping the shape of the housing space; and, a third function of providing
a footing
for smoothly performing work associated with the crawl 100, for example,
feeding
work for fish and the like housed in the housing space. Additionally, in order
to
sufficiently fulfill the third function, the frame body 3 includes a plate not
shown (plate
3a: see Fig. 5) along the outer periphery.
[0033]
<Fastening Side net 2 to Frame body 3>
Next, fastening the upper end 2a of the side net 2 to the frame body 3 will be
described in detail. In the embodiment, the upper end 2a of the side net 2 is
fastened
to the frame body 3 via an insulating member 5.
[0034]
Here, reference is made to Fig. 5, which is a cross sectional view taken along
line A-A in Fig. 1 and viewed in an arrow direction. As shown in Fig. 5, the
frame
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body 3 includes, from the outer peripheral side to the inner peripheral side,
the plate 3a,
a main frame body 3b, a pipe member 3c having a predetermined diameter which
is
fixed to the main frame body 3b via a bridging member 3d and eases fastening
the
upper end 2a of the side net 2 to the frame body 3, in this order. That is,
the metallic
pipe member 3c is provided on the inner peripheral side of the frame body 3.
Additionally, the insulating member 5 having a thickness of 2 to 5 [mm] is
wound
around an outer peripheral surface of the pipe member 3c, the insulating
member 5
being composed of resin of vinyl chloride, polyethylene, polypropylene,
polyester or
the like. Additionally, a slit (not shown) is provided in the insulating
member 5 so
that the insulating member 5 is easily wound around the outer peripheral
surface of the
pipe member 3c.
[0035]
The upper end 2a of the side net 2 is fastened to the frame body 3 via the
insulating member 5 and with use of a fastening wire rod 6 composed of a
material the
same as that of the side net 2. That is, the fastening wire rod 6 includes a
knot (not
shown), passes through the inside of the stitch of the side net 2, and is
wound around
an outer periphery of the insulating member 5. Accordingly, the upper end 2a
of the
side net 2 is fastened to the frame main body 3b via the fastening wire rod 6
passing
through the stitch of the side net 2, the insulating member 5 around which the
fastening
wire rod 6 is wound, and the pipe member 3c having the outer peripheral
surface
around which the insulating member 5 is wound.
[0036]
Moreover, in the embodiment, a reinforcing wire rod 7, which serves as a wire
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~
rod for aligning the ends of the side net 2, are made to penetrate the ends of
the side net
2 (upper end 2a side shown in Fig. 5, lower end 2b side shown in Fig. 3).
Additionally, the reinforcing wire 7, which is made to penetrate the ends on
the upper
end 2a side of the side net 2, is arranged on the inner peripheral side of the
fastening
wire rod 6, and the other reinforcing wire 7, which is made to penetrate the
ends on the
lower end 2b side of the side net 2, is arranged on the inner peripheral side
of the
connecting member 4 shown in Fig. 4.
[0037]
Next, a manufacturing method of the crawl 100 will be described. Here, it is
assumed that the frame body 3 including the floats is arranged along the sea
surface.
[0038]
<First Step: Set-up of Floating member 10>
In the step, the floating member 10 having the floating property for seawater
is
provided. Fig. 7 is a perspective view of the crawl according to the
embodiment of
the present invention, and shows the first step of the manufacturing method of
the
crawl. The floating member 10 is composed of, for example, a resin float
having a
floating and sinking property, and is arranged at the approximate center of
the inner
peripheral side of the frame body 3.
[0039]
<Second Step: Laying Surface member 9>
In the step, a surface member is laid on the inner peripheral side of the
frame
body 3 so as to be flush with the frame body 3. The step will be described in
detail
below.
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[0040]
Here, reference is made to Fig. 8, which is a view showing a part of the
second
step of the manufacturing method of the crawl, and is similar to Fig. 7. As
shown in
Fig. 8, first, a plurality of bridging wire rods 8a are arranged and laid on
the inner
peripheral side of the frame body 3.
[0041]
The bridging wire rod 8a is composed of iron or an iron alloy, and has a
diameter of 2 to 4 [mm]. Additionally, the plurality of bridging wire rods 8a
are
arranged at a predetermined interval (e.g. 50 [cm]) on the inner peripheral
side of the
frame body 3. At this time, each end of the bridging wire rods 8a is fastened
to the
pipe member 3c. That is, each bridging wire rod 8a is bridged between a pair
of pipe
members 3c and 3c opposite to each other. If a proper tension is applied to
the
bridging wire rod 8a fastened between the pipe members 3c and 3c, anything is
applicable as a fastening method of the wire rod 8a. Moreover, at this time,
the
bridging wire rod 8a is bridged so as to be positioned above the floating
member 10.
[0042]
Here, reference is made to Fig. 9, which is a view showing a part of the
second
step of the manufacturing method of the crawl, and is similar to Fig. 7. The
bridging
wire rods 8a are arranged and laid on the inner peripheral side of the frame
body 3 as
described above, and then other bridging wire rods 8b (on the bridging wire
rods 8a)
are arranged and laid on the inner peripheral side of the frame body 3 so as
to be
orthogonal to the bridging wire rods 8a.
[0043]
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Material, diameter, interval and fastening method to the pipe member 3c of the
bridging wire(s) 8b are similar to those of the bridging wire(s) 8a.
[0044]
The plurality of bridging wire rods 8a and the bridging wire rods 8b are thus
laid on the inner peripheral side of the frame body 3 so as to be orthogonal
to each
other, and thus the surface member 9 to be flush with the frame body 3 is
laid.
Additionally, the surface member 9 is thus strongly supported by both the
frame
member 3 having the floating property for seawater and the floating member 10
so as
to be separated from the sea surface at a predetermined distance.
[0045]
<Third Step: Laying Bottom net 1>
In the step, the bottom net 1 is developed on the inner peripheral side of the
frame body 3 so as to be flush with the frame body 3. That is, the bottom net
1 is
developed on the surface member 9 flush with the frame body 3. The step will
be
described in detail below.
[0046]
Here, reference is made to Fig. 10, which is a view showing a part of the
third
step of the manufacturing method of the crawl, and is similar to Fig. 7. As
shown in
Fig. 10, the bottom net 1 is divided into the predetermined number of nets 1
a, 1 a... in a
direction parallel to an extending direction D I of the row wires a
constituting the
bottom net 1 in advance of being developed on the surface member 9. These nets
I a,
1 a... are carried to the inner peripheral side of the frame body 3 in an
extending
direction of the bridging wire rods 8b constituting the surface member 9. At
this time,
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since the bridging wire rods 8b are arranged on the bridging wire rods 8a, the
bridging
wire rods 8b serve as a guiding mechanism for carrying the nets l a, 1 a... to
the inner
peripheral side of the frame body 3, and thus smooth carriage of the nets 1 a,
1 a... is
realized.
[0047]
Next, the nets 1 a, 1 a... carried to the inner peripheral side of the frame
body 3
are developed in an extending direction D2 of the bridging wire rods 8b, and
the ends
(ends in a developing direction) of the nets l a, l a adjacent to each other
are connected
to each other. Thus, the bottom net 1 is developed on the inner peripheral
side of the
frame body 3 so as to be flush with the frame body 3. Moreover, the ends of
the nets
1 a, 1 a adjacent to each other may be stitched to be connected to each other
with use of
another prepared row wire a, or may be connected to each other by another
known
connecting method.
[0048]
<Fourth Step: Connection of Side net 2 to Bottom net 1>
In the step, the side net 2 is annularly connected to a peripheral edge of the
bottom net 1 in a state of being developed on the inner peripheral side of the
frame
body 3 so as to be flush with the frame body 3, and is bent in a direction
orthogonal to
an inner peripheral edge of the frame body 3 so that the upper end 2a of the
side net 2
is arranged along the inner peripheral edge of the frame body 3. The step will
be
described in detail below.
[0049]
Here, reference is made to Fig. 11, which is a view showing a part of the
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fourth step of the manufacturing method of the crawl, and is similar to Fig.
7.
Moreover, the thick line arrow in Fig. 11 indicates the extending direction of
the row
wires a.
[0050]
As shown in Fig. 1, the side net 2 is annularly formed when the crawl 100 is
in
use. However, in consideration of workability of assembling the crawl 100, the
side
net 2 is carried to the inner peripheral side of the frame body 3 with the net
2 divided
into a great number of parts in a direction orthogonal to the extending
direction of the
row wire a, and spirally rolled.
[0051]
Then, the side net 2 divided and spirally rolled is developed and mounted on
the bottom net 1 so that the plurality of row wires a constituting the side
net 2
vertically extend when the crawl 100 is in use. At this time, the lower end 2b
of the
divided side net 2 is set to be arranged along the peripheral edge of the
bottom net 1.
Then, the divisional parts of the side net 2 are stitched so that the side net
2 is annularly
formed on the bottom net 1. Fig. 11 is a view showing a state where the side
net 2 to
be annularly formed is completed not by the whole periphery but by half the
periphery.
[0052]
Next, as described above, the reinforcing members 7 are made to penetrate the
ends of the upper end 2a side and the lower end 2b side of the side net 2
annularly
formed on the bottom net 1, respectively (see Fig. 5 together).
[0053]
Then, the side net 2 is connected to the peripheral edge of the bottom net 1.
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As described above, the connecting member 4 formed in the coil shape is used
in this
connection. At this time, the reinforcing wire 7 penetrating the end on the
lower end
2b side of the side net 2 must be arranged on the inner peripheral side of the
connecting
member 4.
[0054]
Fig. 12 is a view showing a part of the fourth step of the manufacturing
method of the crawl, and is similar to Fig. 7. The side net 2 is annularly
connected to
the peripheral edge of the bottom net 1, and then, as shown in Fig. 12, is
bent in a
direction D3 (indicated by a thick line arrow in Fig.12) orthogonal to the
inner
peripheral edge of the frame body 3 so that the upper end 2a of the side net 2
is
arranged along the inner peripheral edge of the frame body 3. The step will be
described in detail below.
[0055]
That is, the side net 2 is folded back in the direction D3 shown in Fig. 12 so
that the upper end 2a of the side net 2 positioned at the approximate center
of the frame
body 3 in the state shown in Fig. 11 is arranged along the inner peripheral
edge (pipe
member 3c in the embodiment) of the frame body 3.
[0056]
<Fifth Step: Fastening Side net 2 to Frame body 3>
In the step, the upper end 2a of the side net 2 is fastened to the frame body
3
before releasing the state where the bottom net 1 is flush with the frame body
3.
[0057]
Here, reference is made to Fig. 5, which is a view showing a state of the
upper
CA 02669265 2009-05-06
end 2a of the side net 2 being fastened to the frame body 3. As shown in the
figure,
the upper end 2a of the side net 2 is fastened to the pipe member 3c of the
frame body
3 with use of the fastening wire rod 6. At this time, since the insulating
member 5 is
interposed between the fastening wire rod 6 and the pipe member 3c, the
fastening wire
rod 6 and the pipe member 3c are electrically insulated from each other.
[0058]
<Sixth Step: Releasing state where Bottom net 1 is flush with Frame body 3>
In the step, the state is released where the bottom net 1 is flush with the
frame
body 3. That is, the floating member 10 shown in Fig. 7 is removed, the
bridging
wire rods 8a and bridging wire rods 8b laid on the inner peripheral side of
the frame
body 3 are slowly thinned out as shown in Fig. 9, the bottom net 1 is slowly
sunk into
the sea due to its own weight, and thus the state is released where the bottom
net 1 is
flush with the frame body 3. Thus, the side net 2 bent as shown in Fig. 12 is
vertically developed to shift into the state shown in Fig. 1, and
manufacturing the crawl
100 is completed.
[0059]
As described above, the crawl 100 of the embodiment is constituted as follows.
That is, the crawl 100 includes the bottom net 1, the side net 2 which is
peripherally
provided on the bottom net 1, and the frame body 3 which is arranged along the
sea
surface and to which the upper end 2a of the side net 2 is fastened. The side
net 2 is
constituted in a manner that the row wires a formed by bending and forming
metallic
wires each into a predetermined shape are arranged in a row and interlocked
with each
other. The side net 2 is attached to the bottom net 1 and the frame body 3 so
that the
21
CA 02669265 2009-05-06
plurality of row wires a vertically extend when the crawl 100 is in use.
According to
this constitution, even if any of the plurality of row wires a constituting
the side net 2 is
broken, further enlargement of an opening caused by a breakage can be
controlled by
other row wires a adjacent to the broken row wire a. Additionally, according
to this
constitution, since its own weight of the bottom net 1 makes each of row wires
a of the
side net 2 as a line, an extreme advantage is obtained in terms of strength,
compared
with the case where, for example, row wires a are arranged so as to
horizontally extend
and its own weight of the bottom net 1 makes each of row wires a of the side
net 2
further bent. In the crawl 100, since the row wires a of the side net 2
vertically extend,
load is applied to the wires in a wire axis direction. In a material which
forms the
wire, generally, a longitudinal modulus (Young's modulus) is larger than a
lateral
modulus (shearing modulus), and tensile stress is larger than shearing stress.
Thus,
the risk that its own weight has, a breakage or deformation of the crawl, can
be
controlled, and the crawl 100 can be upsized at minimal risk. Since the
plurality of
row wires a of the side net 2 vertically extend, the crawl 100 attempts to
remain at the
original position in accordance with bend-rigidity owned by the row wires a
and its
own weight, in the case where an external force generated by tides or the like
parallel
to the sea surface is applied to the side net 2. Thus, the crawl 100 has an
excellent
shape retaining property. Further, in the crawl 100, since the plurality of
row wires a
of the side net 2 vertically extend, they receive compression force in the
case where an
external force generated by pushing-up of seawater from the bottom net 1 side
is
applied to the side net 2. That is, resistance force of the row wires a
against the
compression force makes the crawl 100 keep its shape, and thus the crawl 100
has an
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CA 02669265 2009-05-06
excellent shape retaining property.
[0060]
The crawl 100 is further constituted as follows. That is, the side net 2 is
peripherally provided on the bottom net 1 via the coil-shaped connecting
member 4.
The side net 2, the bottom net I and the connecting member 4 are composed of
the
same metallic material. According to this constitution, galvanic corrosion
between
the bottom net 1 or the side net 2 and the connecting member 4 can be avoided,
and the
side net 2 can be easily connected to the bottom net 1. Further, this
constitution
allows the side net 2 to rotate relatively to the bottom net 1.
[0061]
The crawl 100 is further constituted as follows. That is, the bottom net 1 and
the side net 2 are composed of copper or a copper alloy. According to the
material, a
crawl can be obtained that stain-proof effect and weed-proof effect are
exerted by
oligodynamie. Further, since the stitches of the side net 2 are not closed
according to
the stain-proof effect and weed-proof effect, the following extremely
advantageous
effects (1) to (3) are obtained: (1) labor for cleaning the crawl 100 is
reduced; (2)
seawater containing a sufficient amount of oxygen is securely supplied into
the crawl
100; and, (3) environment load is reduced since weed, shellfish and the like
are hardly
piled up.
[0062]
The crawl 100 is further constituted as follows. That is, the upper end 2a of
the side net 2 is fastened to the frame body 3 via the insulating member 5.
According
to this constitution, since the galvanic corrosion between the side net 2 and
the frame
23
CA 02669265 2009-05-06
body 3 is securely avoided even if the frame body 3 is composed of a material
different
from that of the side net 2, a material of the frame body 3 can be freely
selected.
[0063]
The crawl 100 is further constituted as follows. That is, the length of the
outer peripheral part of the upper end of the side net 2 attached to the frame
body 3 is
50m or more. According to this constitution, various advantages are obtained
by
upsizing the crawl. For example, (1) in the case of a general crawl with the
size of
10mxlOmX8m, the surface area for use is 420m2, and the volume for use is
800m3; and,
(2) in the case of a crawl with the size of 24mx24mx 10m, the surface area for
use is
1536m2, and the volume for use is 5760m3. The rates of the use area to the
volume in
the crawl are 1.90m3/m2 in (1), and 3.75m3/m2 in (2). That is, this results in
a savings
cost of materials to be used for unit volume of the crawl. If the volume of
the crawl is
increased by upsizing the crawl 100, the number of contacts between fish or
contacts of
fish and the net is reduced, and stress of the fish can be reduced, in the
case of, for
example, fish cultivation and the like. Thus, a more excellent cultivation
environment
can be provided.
[0064]
The crawl 100 is further constituted as follows. That is, the fastening wire
rod 6 used in attaching the side net 2 to the frame body 3 is provided by at
least two
meshes of the net. According to this constitution, its own weight of the net
can be
prevented from deforming the upper part of the net. Additionally, load to be
applied
to the net and fatigue of the net are reduced, and endurance thereof can be
improved.
[0065]
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CA 02669265 2009-05-06
According to the embodiment described above, there is provided a
manufacturing method of the crawl 100 including the bottom net 1, the side net
2
which is peripherally provided on the bottom net 1, and the frame body 3 which
is
arranged along the sea surface and to which the upper end 2a of the side net 2
is
fastened, including the steps of: annularly connecting the side net 2 to the
peripheral
edge of the bottom net 1 which is in a state of being developed on the inner
peripheral
side of the frame body 3 so as to be flush with the frame body 3; and, bending
the side
net 2 in the direction orthogonal to the inner peripheral edge of the frame
body 3 so
that the upper end 2a of the side net 2 is arranged along the inner peripheral
edge of the
frame body 3. According to this method, the side net 2 is connected to the
frame
body 3 and the bottom net 1 with the frame body 3 and the bottom net 1 flush
with
each other.
[0066]
The manufacturing method of the crawl 100 further includes the step of
fastening the upper end 2a of the side net 2 to the frame body 3 before
releasing the
state where the bottom net 1 is flush with the frame body 3. According to this
method,
the side net 2 is developed by action of its own weight of the bottom net 1
only by
releasing the state where the bottom net I is flush with the frame body 3.
[0067]
The manufacturing method of the crawl 100 further includes the step of laying
the surface member 9 to be flush with the frame body 3 on the inner peripheral
side of
the frame body 3. According to this method, the bottom net 1 can be developed
on
the inner peripheral side of the frame body 3 so as to be flush with the frame
body 3
CA 02669265 2009-05-06
regardless of an environment of a manufacturing site of the crawl 100. That
is, the
manufacturing site of the crawl 100 can be placed on the sea.
[0068]
The above step is as follows. That is, a plurality of wire rods (bridging wire
rods 8a) are arranged and laid on the inner peripheral side of the frame body
3, and
then, a plurality of other wires (bridging wire rods 8b) are arranged and laid
on the
inner peripheral side of the frame body 3 so as to be orthogonal to the wires
(bridging
wire rods 8a). According to this step, the surface member 9 is strengthened,
and thus
the state can be securely kept where the bottom net 1 is flush with the frame
body 3
when the bottom net 1 is developed on the surface member 9, and other wires
(bridging
wire rods 8b) serve as a guiding mechanism for developing the bottom net 1.
[0069]
The manufacturing method of the crawl 100 further includes the step of
providing the floating member 10 having the floating property for the seawater
under
the surface member 9. According to this method, the state can be more securely
kept
where the bottom net 1 is flush with the frame body 3.
[0070]
A suitable embodiment of the present invention is described above. However,
the above embodiment can be modified as follows and carried out.
[0071]
That is, for example, the crawl 100 may be manufactured not only on the sea
but on land. In the case where the crawl 100 is manufactured on land, the step
of
using the surface member 9 and the floating member 10 is not always required.
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CA 02669265 2009-05-06
Moreover, the crawl 100 manufactured on land may be lifted up by, for example,
heavy machinery such as a crane, and carried to a predetermined place.
[0072]
The bottom net 1 and the side net 2 may be composed of metal such as iron or
an iron alloy, in place of copper or a copper alloy.
[0073]
The frame body 3 may be composed of resin of polyethylene, polypropylene,
polyester, nylon or FRP.
[0074]
The extending direction of the row wires a constituting the bottom net 1 is
not
limited.
[0075]
In terms of smooth manufacture of the crawl 100, preferably, temporary
fastening is properly performed in fastening the bottom net 2 to the bottom
net 1.
27
