U.S. patent application number 16/088705 was filed with the patent office on 2021-01-07 for circular knitted tubular structure, and manufacturing method and manufacturing device of the same.
The applicant listed for this patent is TOYOBO STC CO., LTD.. Invention is credited to Hideki KAWABATA, Hiroyuki OKAWA, Kazushi SUEKI.
Application Number | 20210002799 16/088705 |
Document ID | / |
Family ID | |
Filed Date | 2021-01-07 |
![](/patent/app/20210002799/US20210002799A1-20210107-D00000.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00001.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00002.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00003.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00004.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00005.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00006.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00007.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00008.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00009.png)
![](/patent/app/20210002799/US20210002799A1-20210107-D00010.png)
View All Diagrams
United States Patent
Application |
20210002799 |
Kind Code |
A1 |
OKAWA; Hiroyuki ; et
al. |
January 7, 2021 |
CIRCULAR KNITTED TUBULAR STRUCTURE, AND MANUFACTURING METHOD AND
MANUFACTURING DEVICE OF THE SAME
Abstract
A circular knitted tubular structure manufactured at low cost
with use of a circular knitting machine is highly adaptable to
bending due to flexibility, having tube inner and outer surfaces so
soft that no abnormal noise is produced, and hence useful as a
sleeve covering and thereby protecting a cable, such as an
electrical wire and an optical fiber cable. The circular knitted
tubular structure is formed of a fabric tape formed of circular
knitted fabric having front yarn forming loops and back yarn having
a higher heat shrinkage ratio than the front yarn and formed into a
scrolled shape by letting the back yarn undergo heat shrinkage to
have an overlap portion circumferentially overlapping 1.3 to 2.5
times. Apparatus for manufacturing the circular knitted tubular
structure includes a furnace and a shape-forming jig.
Inventors: |
OKAWA; Hiroyuki;
(Hirakata-shi, Osaka, JP) ; SUEKI; Kazushi;
(Osaka-shi, Osaka, JP) ; KAWABATA; Hideki;
(Osaka-shi, Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOBO STC CO., LTD. |
Osaka-shi |
|
JP |
|
|
Appl. No.: |
16/088705 |
Filed: |
March 17, 2017 |
PCT Filed: |
March 17, 2017 |
PCT NO: |
PCT/JP2017/010997 |
371 Date: |
September 26, 2018 |
Current U.S.
Class: |
1/1 |
International
Class: |
D04B 1/22 20060101
D04B001/22; D04B 1/16 20060101 D04B001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2016 |
JP |
2016-074272 |
Claims
1. A circular knitted tubular structure formed of a circular
knitted fabric tape having a length direction as a course
direction, wherein: the circular knitted fabric tape has a cut edge
in the length direction cut and left as is and is formed into a
scrolled tubular shape to have an overlap portion in a width
direction.
2. The circular knitted tubular structure according to claim 1,
wherein: the circular knitted fabric tape is formed of circular
knitted fabric using yarn forming a right side and high shrinkage
yarn passed on a wrong side and having a higher heat shrinkable
property than the yarn forming the right side; and the overlap
portion of the circular knitted fabric tape circumferentially
overlaps 1.3 to 2.5 times in a scrolled shape.
3. The circular knitted tubular structure according to claim 2,
wherein: circular knitted fabric is a single knit and the high
shrinkage yarn is inserted in the width direction.
4. The circular knitted tubular structure according to claim 2,
wherein: the circular knitted fabric is a double knit and the high
shrinkage yarn is passed in weave on the wrong side at least in
part.
5. The circular knitted tubular structure according to claim 2,
wherein; a difference in dry heating shrinkage ratio between the
yarn forming the right side of the circular knitted fabric and the
high shrinkage yarn is 3 to 80%.
6. The circular knitted tubular structure according to claim 2,
wherein: the yarn passed on the wrong side of the circular knitted
fabric includes at least one of monifilament having a single yarn
fineness of 30 to 2400 dtex or multi-filament having a single yarn
fineness of 30 to 2400 dtex.
7. The circular knitted tubular structure according to claim 2,
wherein; knit loops forming the right side of circular knitted
fabric include loops having at least two loop lengths; and loops
having a shortest loop length account for 20 to 75% of all knit
loops per unit area and a loop length of the loops having the
shortest loop length is 20 to 80% of a loop length of loops having
a longest loop length.
8. A manufacturing method of a circular knitted tubular structure,
comprising: knitting front yarn and back yarn having a higher heat
shrinkage ratio than the front yarn into circular knitted fabric
with a circular knitting machine by forming a front loop from the
front yarn and passing the back yarn behind the front loop;
producing a fabric tape by cutting the circular knitted fabric
knitted in advance in a course direction which is a length
direction of knitted fabric at an interval of 1 to 30 cm in a width
direction; and forming the fabric tape into a scrolled shape with
one end overlapping the other to have a scrolled overlap portion
circumferentially overlapping 1.3 to 2.5 times in the scrolled
shape by passing the fabric tape through a dried furnace at 70 to
190.degree. C. in a range within which a length of the fabric tape
becomes 0.8 to 1.3 times longer than an original length while the
fabric tape is passed through a conical shape-forming induction jig
which has a circular opening at an inlet and a scrolled, tapered
opening at an outlet.
9. A manufacturing device of a circular knitted tubular structure,
comprising: a furnace heating a fabric tape formed of circular
knitted fabric; and a shape-forming induction jig shaping the
fabric tape, the manufacturing device being characterized in that:
the shape-forming induction jig is of a conical shape having a
circular opening at an inlet and a scrolled, tapered opening at an
outlet; and the shape-forming induction jig shapes the fabric tape
inserted into the inlet and pulled out from the outlet into a
scrolled shape with one end overlapping the other and allows the
fabric tape to remain scrolled by heating in the furnace.
Description
TECHNICAL FIELD
[0001] The present invention relates to a tubular structure formed
of circular knitted fabric and a manufacturing method thereof, and
more particularly, to a circular knitted tubular structure suitable
to a sleeve covering and thereby protecting a cable, such as an
electrical wire and an optical fiber cable, installed to a vehicle
that vibrates when driven, such as an automobile, and to a
manufacturing method and a manufacturing device thereof.
BACKGROUND ART
[0002] Patent Literature 1 describes a corrugated tube having a cut
in a length direction and an opening formed to open and close in a
circumferential direction, which is adopted in the related art as
the protecting sleeve described above. Besides a corrugated tube, a
protecting sleeve formed of braid, warp knit, and weft knit is
used. A protecting sleeve formed of knitted fabric as described in
Patent Literature 2 specified below is also used. Further, an
acoustic absorption protecting sleeve formed of woven fabric as
described in Patent Literature 3 is proposed.
CITATION LIST
Patent Literatures
[0003] Patent Literature 1: JP-A-2015-37333
[0004] Patent Literature 2: JP-A-2003-278058
[0005] Patent Literature 3: JP-T-2003-506579 [0006] (the term
"JP-T" as used herein means a published Japanese translation of a
PCT patent application)
SUMMARY OF INVENTION
Technical Problem
[0007] The corrugated tube described in Patent Literature 1
specified above has stretching properties and flexibility to some
extent due to its corrugated shape. However, because the corrugated
tube is made of hard synthetic resin to maintain durability, the
corrugate tube fails to achieve sufficient stretching properties
and flexibility in actual use. Moreover, when used in a vibrating
object like an automobile, a cable stored in the corrugated tube
and an inner surface of the corrugate tube hit against each other,
in which case not only an abnormal noise, such as a chattering
noise, is produced, but also the cable may possibly be damaged. A
drawback of the corrugated tube is a need to overcome such an
inconvenience by covering the cable with soft fabric or the like in
advance or by bonding a shock absorber to the inner surface of the
corrugated tube before the cable is stored in the corrugated tube.
In addition, because the corrugate tube is hard, an abnormal noise
may possibly be produced when the corrugated tube hits against a
nearby object.
[0008] A wiring cord cover described in Patent Literature 2
specified above directly uses a tubular body. A diameter of
cylindrically knitted fabric is determined by a cylinder diameter
of a knitting machine. Hence, while cylindrically knitted fabric of
a same diameter can be manufactured continuously, a cylinder needs
to be replaced with another cylinder having a different diameter to
manufacture cylindrically knitted fabric of various types each
having a different diameter. Accordingly, as many knitting machines
and cylinders as the number of different diameters are required.
The wiring cord cover therefore has a drawback that facility costs
are required and hence manufacturing costs are increased. In
addition, because the cover has openings only at both ends of the
cylindrically knitted fabric, a wiring cord cannot be covered with
the cover after the wiring cord is connected to a device.
[0009] The acoustic absorption protecting sleeve described in
Patent Literature 3 specified above is formed of woven fabric. The
sleeve is therefore thin and lacks pliability and stretching
properties. Hence, when the sleeve is curved, the sleeve fails to
curve smoothly and bends instead, which raises a problem that a
wiring stored inside is locally pressed hard. While a purpose of
the sleeve is to reduce acoustic vibrations, the sleeve formed of
thin, unpliable woven fabric exerts only limited vibration
absorbing performance. In addition, woven fabric having an
extremely fine width needs to be manufactured to form the sleeve.
Hence, the acoustic absorption sleeve has a drawback in
productivity. This drawback may be eliminated by using a fabric
tape cut narrow from wide woven fabric prepared in advance.
However, this countermeasure cannot be adopted because a warp of
woven fabric readily frays and when heat cutting is applied to
prevent fray, a melted cut portion becomes so hard that an
electrical wire filled inside or a material making contact from
outside is readily damaged.
[0010] The present invention was devised in view of the current
situation of the related art and has an object to provide a
circular knitted tubular structure manufactured at low costs,
highly adaptable to bending due to pliability, having tube inner
and outer surfaces so soft that no abnormal noise is produced, and
hence useful as a sleeve covering and thereby protecting a cable,
such as an electrical wire and an optical fiber cable, and a
manufacturing method and a manufacturing device thereof.
Solution to Problem
[0011] Inventors of the present invention conducted an assiduous
study and succeeded in providing an excellent tubular structure of
the present invention by making improvements, regarding the
circular knitted fabric, in points a, b, and c as follows.
[0012] a. Providing a tube with an end face which prevents the tube
from fraying when a wiring is stored from a tube side surface and
eliminates a concern about snagging or the like.
[0013] b. Providing a knitted fabric construction to shape a fabric
tape cut from knitted fabric into an even and neat tubular
structure and a shape-forming method.
[0014] c. Providing a knitted fabric construction to confer a shape
retaining property and an elastic bouncing property to a tubular
body.
[0015] More specifically, regarding the point a, the inventors paid
attention to the fact that circular knitted fabric hardly frays
when cut in a course (length) direction because all strands of yarn
forming the circular knitted fabric is knitted in a wale (width)
direction while only loops are chained in the course direction and
no yarn is passed linearly in the course direction (longitudinal
direction). The inventors discovered that a sleeve with a
fray-proof side edge can be formed from a tubular structure by
cutting circular knitted fabric in the course direction with an
edged tool or the like after a width is adjusted to a circumference
of a desirable tubular structure and using a cut surface left as is
as the side edge of the sleeve.
[0016] Regarding the point b, the inventors discovered that a
tubular structure having a neat cylindrical appearance is formed
from a fabric tape cut from knitted fabric in the course direction
by using different types of yarn each having a different heat
shrinkable property on right and wrong sides of knitted fabric
(corresponding to inside and outside of a tubular structure) and
letting the yarn on the wrong side shrink more than does the yarn
on the right side.
[0017] Regarding the point c, the inventors discovered that even
when large size yarn is cut left as is after the large size yarn is
passed appropriately on an inner side of a tube to maintain a neat
tubular structure at normal times and also to confer restorability
against an impact or hard pressing from the outside, a cut part of
the large size yarn does not appear on the right side of the
knitted fabric and hence damage on a contact portion on the outside
and snagging can be prevented. The inventors achieved the present
invention from the discoveries as above.
[0018] That is, a circular knitted tubular structure according to
claim 1 of the present invention is formed of a circular knitted
fabric tape having a length direction as a course direction and
characterized in that the circular knitted fabric tape has a cut
edge in the length direction cut and left as is and is formed into
a scrolled tubular shape to have an overlap portion in a width
direction.
[0019] A circular knitted tubular structure according to claim 2 of
the present invention has the construction of the circular knitted
tubular structure set forth in claim 1 and is further characterized
in that the circular knitted fabric tape is formed of circular
knitted fabric using yarn forming a right side and high shrinkage
yarn passed on a wrong side and having a higher heat shrinkable
property than the yarn, and that the overlap portion of the
circular knitted fabric tape circumferentially overlaps 1.3 to 2.5
times in a scrolled shape. The yarn forming the right side referred
to herein is not limited to yarn forming loops and may also include
yarn exposed to the right side.
[0020] A circular knitted tubular structure according to claim 3 of
the present invention has the construction of the circular knitted
tubular structure set forth in claim 1 or 2 and is further
characterized in that circular knitted fabric is a single knit and
the high shrinkage yarn is inserted in a width direction.
[0021] A circular knitted tubular structure according to claim 4 of
the present invention has the construction of the circular knitted
tubular structure set forth in claim 1 or 2 and is further
characterized in that circular knitted fabric is a double knit and
the high shrinkage yarn is passed in weave on a wrong side at least
in part.
[0022] A circular knitted tubular structure according to claim 5 of
the present invention has the construction of the circular knitted
tubular structure set forth in any one of claims 1 through 4 and is
further characterized in that a difference in dry heating shrinkage
ratio between yarn forming a right side of circular knitted fabric
and the high shrinkage yarn is 3 to 80%.
[0023] A circular knitted tubular structure according to claim 6 of
the present invention has the construction of the circular knitted
tubular structure set forth in any one of claims 1 through 5 and is
further characterized in that yarn including monofilament having a
single yarn fineness of 30 to 2400 dtex or multi-filament having a
single yarn fineness of 30 to 2400 dtex or both is passed on a
wrong side of circular knitted fabric.
[0024] A circular knitted tubular structure according to claim 7 of
the present invention has the construction of the circular knitted
tubular structure set forth in any one of claims 1 through 6 and is
further characterized in that knit loops forming a right side of
circular knitted fabric include loops having at least two loop
lengths, and that loops having a shortest loop length account for
20 to 75% of all knit loops per unit area and a loop length of the
loops having the shortest loop length is 20 to 80% of a loop length
of loops having a longest loop length.
[0025] A manufacturing method of a circular knitted tubular
structure according to claim 8 of the present invention is
characterized by including: knitting front yarn and back yarn
having a higher heat shrinkage ratio than the front yarn into
circular knitted fabric with a circular knitting machine by forming
a front loop from the front yarn and passing the back yarn behind
the front loop; producing a fabric tape by cutting the circular
knitted fabric knitted in advance in a course direction which is a
length direction of knitted fabric at an interval of 1 to 30 cm in
a width direction; and forming the fabric tape into a scrolled
shape with one end overlapping the other to have a scrolled overlap
portion circumferentially overlapping 1.3 to 2.5 times in the
scrolled shape by passing the fabric tape through a dried furnace
at 70 to 190.degree. C. in a range within which a length of the
fabric tape becomes 0.8 to 1.3 times longer than an original length
while the fabric tape is passed through a conical shape-forming
induction jig which has a circular opening at an inlet and a
scrolled, tapered opening at an outlet.
[0026] A manufacturing device of a circular knitted tubular
structure according to claim 9 of the present invention includes a
furnace heating a fabric tape formed of circular knitted fabric and
a shape-forming induction jig shaping the fabric tape, and is
characterized in that: the shape-forming induction jig is of a
conical shape having a circular opening at an inlet and a scrolled,
tapered opening at an outlet, and that the shape-forming induction
jig shapes the fabric tape inserted into the inlet and pulled out
from the outlet into a scrolled shape with one end overlapping the
other and allows the fabric tape to remain scrolled by heating in
the furnace.
Advantageous Effects of Invention
[0027] According to the present invention, a fabric tape cut from
circular knitted fabric in the length direction hardly frays from a
cut edge of the fabric tape. Hence, a circular knitted tubular
structure formed of the fabric tape has an advantage that fray
hardly occurs. The tubular structure can be manufactured from a
fabric tape cut in a desirable width from circular knitted fabric
made by a single circular knitting machine independently of a
cylinder diameter and can be therefore manufactured at low costs.
The circular knitted fabric itself has stretching properties.
Hence, a circular knitted tubular structure formed of the circular
knitted fabric is sufficiently pliable and has high adaptability to
bending. The fabric tape is allowed to form a tubular structure
naturally due to heat shrinkage of high shrinkage yarn having a
high heat shrinkage ratio, and an opening can be readily opened
because the fabric tape is formed of circular knitted fabric. Also,
the tubular structure closes by itself after cables or the like are
stored inside due to a shrinking action of the high shrinkage yarn,
thereby eliminating a need to purposely close the tubular
structure. A circular knitted tubular structure formed of circular
knitted fabric has soft tube inner and outer surfaces. Hence, there
is an advantage that no abnormal noise is produced not only when a
cable stored inside hits against the inner surface of the circular
knitted tubular structure due to vibration, but also when the outer
surface of the circular knitted tubular structure hits against a
nearby structure or the like. Consequently, a highly useful
protection sleeve covering and thereby protecting a cable, such as
an electrical wire and an optical fiber cable, can be provided.
[0028] In the manufacturing method of the present invention, the
conical shape-forming induction jig having a circular opening at
the inlet and a scrolled, tapered opening at the outlet and the
furnace are used. A fabric tape can be formed into a scrolled shape
in a reliable manner by the shape-forming induction jig. Also, by
passing the fabric tape formed into a scrolled shape through the
furnace, a circular knitted tubular structure that remains scrolled
in a tubular shape can be manufactured.
BRIEF DESCRIPTION OF DRAWINGS
[0029] FIG. 1 is a schematic view of a right side of a fabric tape
formed of circular knitted fabric and forming a circular knitted
tubular structure using a single knit of the present invention;
[0030] FIG. 2 is a schematic view of a wrong side of the fabric
tape formed of circular knitted fabric and forming a circular
knitted tubular structure using the single knit of the present
invention;
[0031] FIG. 3 is a weave diagram of the single knit shown in FIG. 1
and FIG. 2;
[0032] FIG. 4 is a partial perspective view of a circular knitted
tubular structure using the single knit of the present
invention;
[0033] FIG. 5 is a partial perspective view of a circular knitted
tubular structure using a double knit of the present invention;
[0034] FIG. 6 is a weave diagram of the double knit of the present
invention;
[0035] FIG. 7 is a partial perspective view of a circular knitted
tubular structure having an overlap portion circumferentially
overlapping less than 1.3 times;
[0036] FIG. 8 is a partial perspective view when the circular
knitted tubular structure having the overlap portion
circumferentially overlapping less than 1.3 times is curved;
[0037] FIG. 9 is a partial perspective view of a circular knitted
tubular structure having an overlap portion circumferentially
overlapping more than 2.5 times;
[0038] FIG. 10 is a partial perspective view of a deformed circular
knitted tubular structure as an example of failure in
manufacture;
[0039] FIG. 11 is a schematic view of a manufacturing device
manufacturing a circular knitted tubular structure of the present
invention;
[0040] FIG. 12 is a front perspective view of a shape-forming
induction jig used to manufacture a circular knitted tubular
structure of the present invention;
[0041] FIG. 13A and FIG. 13B are schematic views of an accelerated
wear testing machine, FIG. 13A being a front view and FIG. 13B
being a side view;
[0042] FIG. 14 is a plan view of an entire rubber film;
[0043] FIG. 15 is a partially enlarged front view of the rubber
film;
[0044] FIG. 16 is a picture showing a difference in fray between
Example 1 and Comparative Example 1, (a) in the drawing showing
Example 1 and (b) in the drawing showing Comparative Example 1;
[0045] FIG. 17 is a picture showing evaluation results of
pliability to bending in Example 1 and Comparative Example 1, a row
A in the drawing showing Example 1 and a row B in the drawing
showing Comparative Example 1; and
[0046] FIG. 18 is an enlarged picture showing a difference in
change between tubular structures of Comparative Example 1.
DESCRIPTION OF EMBODIMENTS
Single Knitted Fabric
[0047] A summary of a circular knitted tubular structure of the
present invention and a manufacturing method thereof will be
described by referring to an example of a manufacturing process of
a tubular structure using a single knit. Circular knitted fabric is
knitted in a cylindrical shape by a circular knitting machine to
hang downward below the circular knitting machine. Hence, a
top-bottom direction of the circular knitted fabric coming out from
the knitting machine is a course direction (length direction) and a
horizontal direction is a wale direction (width direction) of the
circular knitted fabric. In the present invention, a fabric tape is
produced by cutting and opening circular knitted fabric knitted in
advance along stitches in the course direction of the knitted
fabric and by cutting the opened knitted fabric in the length
direction at appropriate width intervals. A fabric tape 10 formed
of single circular knitted fabric is shown in FIG. 1 and FIG. 2, in
which a top-bottom direction is the length direction of the fabric
tape and a right-left direction is the width direction. FIG. 3 is a
weave diagram of circular knitted fabric in single knit forming a
circular knitted tubular structure A.
[0048] As is shown in FIG. 3, the single circular knitted fabric
has front yarn 11 (total fineness of 167 dtex, plain knit of 48
polyethylene terephthalate filament textured yarn) forming knit
loops on a right side and back yarn 12 (high shrinkage yarn, 670
dtex, polypropylene monofilament inlay yarn) having a higher heat
shrinkage ratio than the front yarn 11. The front yarn 11 is
chained in right, left, up and down to form knit loops and the back
yarn 12 is inserted through the front yarn 11 forming front loops
on the right, left, up and down in a traverse direction (one tuck
in every three welts). FIG. 1 shows a right side of the fabric tape
10 formed of circular knitted fabric (right side of circular
knitted fabric). FIG. 2 shows a wrong side of the fabric tape 10
formed of circular knitted fabric (wrong side of circular knitted
fabric) and the back yarn 12 behind the front yarn 11 is shown
partially.
[0049] When the fabric tape 10 is heated, the back yarn 12 having a
high heat shrinkage ratio undergoes heat shrinkage. Eventually, the
fabric tape 10 curves in a direction in which both ends in the
width direction come close to each other and becomes deformed into
a cylindrical shape with a side where the back yarn 12 is inserted
facing inward. FIG. 4 shows a cylindrically deformed state. As is
shown in FIG. 4, the fabric tape 10 scrolled with one end
overlapping the other forms the circular knitted tubular structure
A. After an electrical wire or a cable is inserted into the
circular knitted tubular structure A by opening the overlap
portion, a self-closing function is exerted due to shrinkage of the
back yarn 12 which is heat shrinkage yarn and the opening of the
overlap portion naturally closes without having to close the
opening of the overlap portion manually.
Double Circular Knitted Fabric
[0050] An example of a circular knitted tubular structure using a
double knit will now be described. A circular knitted tubular
structure 1A of FIG. 5 is a tubular structure formed of circular
knitted fabric in double knit. FIG. 6 is a weave diagram of
circular knitted fabric in double knit forming the circular knitted
tubular structure 1A. In FIG. 6, numeral 111 denotes front yarn
forming front loops. That is, the front yarn 111 forms front loops
by plain knitting on a cylinder side. Alpha-numerals 112a and 112b
denote back yarns each forming back loops. The back yarn 112a is
high shrinkage yarn. That is, the back yarn 112a forms back loops
on a dial side by plain knitting and the back yarn 112b forms back
loops on the dial side by plain knitting. Besides the front yarn
111 and the back yarns 112a and 112b, circular knitted fabric in
double knit has engaging yarn 113 connecting the front yarn 111 to
the back yarns 112a and 112b by tangling with the front yarn 111
and the back yarns 112a and 112b.
[0051] The front yarn 11 described in Example 1 below is used as
the front yarn 111 and the back yarn 112b. The back yarn 12
described in Example 1 below is used as the back yarn 112a. Also,
24 polyethylene terephthalate filament textured yarn having a total
fineness of 56 dtex is used as the engaging yarn 113. The circular
knitted tubular structure 1A is same as the circular knitted
tubular structure A described above except that it is formed of
circular knitted fabric in double knit in which the back yarn 112a
and the back yarn 112b form back loops, and a description is
omitted herein.
Yarn Forming Right Side
[0052] Composition of circular knitted fabric forming a tubular
structure of the present invention will now be described.
[0053] Yarn forming a right side of knitted fabric (herein,
referred to as front yarn) by forming knit loops on the right side
of knitted fabric is not particularly limited and can be any soft
yarn capable of conferring covering properties to knitted fabric. A
total fineness of the front yarn is preferably 30 to 2400 dtex, and
more preferably 100 to 1200 dtex. When a total fineness is lower
than 30 dtex, the covering properties readily deteriorate.
Conversely, when a total fineness is as high as or higher than 2400
dtex, the tubular structure becomes heavy.
[0054] A single yarn fineness of the front yarn is preferably 0.3
to 20 dtex, and more preferably 0.5 to 10 dtex. When a single yarn
fineness is lower than 0.3 dtex, fiber readily snags to a hangnail
or a protruding object. Conversely, when a single yarn fitness is
over 20 dtex, a fiber end coming out from the edge cut and left as
is makes an individual feel scratchy by touching skin of the
individual, or readily damages a nearby object by rubbing against
the nearby object.
[0055] A material of the front yarn is not particularly limited,
and can be a synthetic fiber, such as polyester, nylon, and
acrylic, a natural fiber, such as cotton, linen, and sheep wool,
and either recycled or semisynthetic organic fiber represented by
rayon, lyocell, cupra, and acetate. Either a filament fiber or a
staple fiber can be used. For example, in a case where a filament
fiber often used for a cable is used, flat yarn may be used or yarn
texturing, such as false twisting, air interlacing, and covering
may be applied. Alternatively, both of a staple fiber and a
filament fiber may be used as staple-filament conjugate spun yarn
formed by using a core spun yarn technique or a fine spinning and
twisting method or as covered yarn formed by covering spun yarn
with a filament fiber. As a relatively inexpensive and durable
example, untextured yarn or false twisted textured yarn of
polyester multi-filament is used preferably.
High Shrinkage Yarn (Back Yarn)
[0056] It is preferable to use yarn having a higher heat shrinkage
ratio (hereinafter, referred to as high shrinkage yarn) than yarn
forming the right side at least in part of the wrong side of the
knitted fabric of the present invention. The high shrinkage yarn is
preferably yarn which shrinks 3 to 80% better than the front yarn
when differential shrinkage between the front yarn and the high
shrinkage yarn on the wrong side is checked in a dry heating
shrinkage test conducted at 150.degree. C. as will be described
below. The differential shrinkage may be selected as needed
according to a diameter of a desirable tubular structure. It is
preferable to set relatively large differential shrinkage of 25 to
80% for a tubular structure having a relatively small diameter of 2
to 20 mm while it is preferable to set relatively small
differential shrinkage for a tubular structure having a diameter
larger than 20 mm.
Large Size Yarn
[0057] In the present invention, it is preferable to use large size
yarn to confer a shape retaining property and an elastic bouncing
property to the tubular structure. Large size yarn includes at
least filaments having single yarn fineness of 30 to 2400 dtex, and
more preferably 300 to 1200 dtex. Large size yarn includes one to
five filaments, more preferably, one filament each having the
single yarn fineness specified above. However, it goes without
saying that large size yarn may be a monofilament alone. Large size
yarn may be used on the right side or the wrong side or both.
[0058] It is most preferable to use high shrinkage, large size yarn
as yarn on the wrong side. In a case where high shrinkage, large
size yarn is on the wrong side, a cut end of large size yarn
shrinks and sinks into the knitted fabric from the end of the
knitted fabric when the tubular structure is shaped by heating.
Hence, there is an advantage that the end of large size yarn hardly
makes contact with an outside.
Material of Back Yarn
[0059] A material of yarn on the wrong side (back yarn) is not
particularly limited and a synthetic fiber filament is used
preferably. For example, a polyester fiber chiefly made of
polyethylene terephthalate, polybutylene terephthalate, or
polytrimethylene terephthalate, a polyamide fiber, such as nylon 6
and nylon 66, a polyolefin fiber, such as polyethylene and
polypropylene, a polyparaphenylene benzoxazole fiber, an aramid
fiber, and a polyarylate fiber can be used.
[0060] These fibers may be conjugated into blended filament yarn,
twisted union yarn, or conjugated yarn. Alternatively, either flat
yarn or textured yarn, such as false twisted textured yarn, may be
used. In a case where high shrinkage, large size yarn is used as
the back yarn of the present invention, a polypropylene fiber or a
polyester fiber can be used preferably.
Material Ratio
[0061] It is preferable that high shrinkage back yarn accounts for
10 to 80 wt % on the basis of the entire circular knitted fabric.
When high shrinkage yarn accounts for the range specified above, a
cylindrical shape having a neatly scrolled, overlap portion can be
easily formed. A more preferable range is 25 to 60 wt %, and
further preferable range is 30 to 60 wt %. When the high shrinkage
yarn accounts for less than 10 wt %, a shape retaining property and
an elastic bouncing property of the tubular structure deteriorate
and a cable protecting effect cannot be fully exerted. Conversely,
when the high shrinkage yarn accounts for more than 80 wt %, high
shrinkage back yarn becomes too thick and readily snags.
Preferably Used Construction of Knitted Fabric
[0062] Knitted fabric used for the tubular structure of the present
invention is knitted fabric formed by knitting yarn while forming
knit loops one by one in the traverse direction. Examples of such
knitted fabric include but not limited to circular knitted fabric
and weft knitted fabric. Weft knitted fabric is advantageous over
circular knitted fabric because there is no need to open the fabric
whereas circular knitted fabric is advantageous over weft knitted
fabric in terms of productivity.
[0063] Circular knitted fabric is largely divided to single
circular knitted fabric and double circular knitted fabric and both
can be used suitably in the present invention. Single circular
knitted fabric is advantageous over double circular knitted fabric
when a thin and narrow tubular structure is desirable whereas it is
preferable to use double circular knitted fabric when a thick and
highly-elastic tubular structure is desirable.
Thickness and Mass Per Unit Area of Knitted Fabric (Gray
Fabric)
[0064] In a case where single circular knitted fabric is used as
the knitted fabric of the present invention, a thickness of the
knitted fabric is preferably 0.3 to 1.0 mm. When the thickness is
less than 0.3 mm, a shape retaining property of the tubular
structure readily deteriorates. Conversely, when the thickness is
over 1.0 mm, the tubular structure becomes hard to twist when
attached to a cable or the like and workability readily
deteriorates. A mass per unit area of single circular knitted
fabric is preferably 70 to 230 g/m.sup.2. When the mass per unit
area is less than 70 g/m.sup.2, a shape retaining property readily
deteriorates. Conversely, when the mass per unit area is over 230
g/m.sup.2, the tubular structure becomes heavy, which may become a
disadvantage in a field where a lighter weight is required, for
example, for vehicular use.
[0065] In a case where double circular knitted fabric is used as
the knitted fabric of the present invention, a thickness of the
knitted fabric is preferably 0.5 to 1.5 mm. When the thickness is
less than 0.5 mm, a shape retaining property of the tubular
structure readily deteriorates. Conversely, when the thickness is
over 1.5 mm, the tubular structure becomes hard to twist when
attached to a cable or the like and workability readily
deteriorates. A mass per unit area of double circular knitted
fabric is preferably 100 to 370 g/m.sup.2. When the mass per unit
area is less than 100 g/m.sup.2, a shape retaining property readily
deteriorates. Conversely, when the mass per unit area is over 370
g/m.sup.2, the tubular structure becomes heavy, which may become a
disadvantage in a field where a lighter weight is required, for
example, for vehicular use.
Overlap
[0066] In the present embodiment, the circular knitted tubular
structure A is formed by shaping the fabric tape 10 into a scrolled
shape with one end overlapping the other to have an overlap portion
circumferentially overlapping 1.3 to 2.5 times. FIG. 7 shows a
circular knitted tubular structure B with an overlap portion
circumferentially overlapping less than 1.3 times, which is not
suitable because, as is shown in FIG. 8, when the circular knitted
tubular structure B enclosing electrical wires, cables, or the like
is curved, the overlap portion opens and the electrical wires, the
cables, or the like enclosed inside become exposed from the
circular knitted tubular structure B. FIG. 9 shows a circular
knitted tubular structure C with an overlap portion
circumferentially overlapping more than 2.5 times, which is not
suitable, either, because it becomes difficult to insert electrical
wires, cables, or the like into an internal space of the circular
knitted tubular structure C.
Diameter and Mass Per Unit Area of Tubular Structure
[0067] A tubular structure formed of circular knitted fabric of the
present invention is applicable with a diameter of 2 to 50 mm. When
the diameter is less than 2 mm, it becomes difficult to form a
scrolled tubular structure. Conversely, when the diameter is over
50 mm, a shape retaining property readily deteriorates because
cables filled inside becomes larger and heavier as the diameter
becomes larger, in which case a protecting effect high enough for
heavy cables cannot be obtained.
[0068] A preferable mass per 1 m in consideration of a diameter of
the tubular structure is indicated by a mass per unit area
(g/m)/diameter (mm). In the case of single circular knitted fabric,
a value of the mass per unit area diameter is preferably set to 0.6
to 1.5. In the case of double circular knitted fabric, the value is
preferably set to 1.2 to 3.0. When the value is less than the lower
limits in the respective ranges specified above, a shape retaining
property of the tubular structure readily deteriorates. Conversely,
when the value is over the upper limits, the tubular structure may
become too heavy.
Fabric Tape
[0069] A fabric tape of the present invention can be produced by
cutting circular knitted fabric in the length direction at
intervals of 1 to 50 cm in the width direction. A preferable width
of the fabric tape is 2 to 30 cm. It becomes difficult to form a
neat cylindrical tubular structure from a fabric tape having a
width of less than 1 cm. Conversely, a tubular structure formed of
a fabric tape having a width of 50 cm or wider is likely to have
poor shape retaining property. Circular knitted fabric can be cut
in the length direction by any cutting method unless a cut surface
becomes hard or readily snags. For example, circular knitted fabric
can be cut by using an edged tool, such as scissors and a knife, an
ultrasonic wave, an airflow, a water flow, and so on. A side
surface of the fabric tape of the present invention cut by any of
the methods specified above is used intact as a selvage. The
manufacturing process of the tubular structure can be thus simpler,
and hence the tubular structure can be manufactured efficiently at
lower costs. In the present invention, a state of fabric cut and
left without any fray-proof treatment is referred to as "cut and
left as is".
[0070] It is also preferable to form a shape of the opened circular
knitted fabric before it is cut into tapes by applying primary heat
treatment at a low temperature, for example, lower than 150.degree.
C. to allow the opened circular knitted fabric to stay in a flat
state without becoming curled under no load. The low-temperature
heat treatment is to improve workability in the following step of
cutting the opened circular knitted fabric into fabric tapes and is
not essential. However, the low-temperature heat treatment is
useful particularly for single circular knitted fabric. That is,
circular knitted fabric readily becomes curled or skewed when
opened. Hence, the opened circular knitted fabric straightened in a
flat state by the low-temperature heat treatment has an advantage
that it becomes easier to produce fabric tapes because the circular
knitted fabric can be cut readily and neatly.
Shape-Forming Method
[0071] The knitted fabric of the present invention cut into a
fabric tape can be formed into a scrolled tubular structure by
heating due to differential shrinkage between the right side and
the wrong side. Any heating method available to heat fibers can be
used and examples include but not limited to dry heating using a
convection of heated air by a hot-air drying machine or the like,
wet heating using a steamer or the like, contact heating with hot
metal or heat medium, wet infra-red radiation, and electromagnetic
heating using a microwave or the like. Alternatively, two or more
of these methods may be used in combination. A method using a
hot-air drying machine or contact heating is preferable.
[0072] For example, when a hot-air drying machine is used, an
operating temperature of the drying machine may be set to 50 to
210.degree. C., and more preferably 70 to 190.degree. C. A fabric
tape can be made long in the length direction. Hence, a device
including heating equipment provided with an inlet and an outlet
and capable of treating a fabric tape continuously is used
preferably in terms of improvement of productivity.
[0073] A fabric tape also shrinks in width by heating. That is, a
width of a fabric tape once formed into a scrolled tubular
structure by heating and developed into a flat state is less than a
width of the fabric tape before heating due to shrinkage and the
latter is reduced to approximately two thirds of the former.
Scrolled Shape-Forming Induction
[0074] As has been described, the knitted fabric of the present
invention cut into a fabric tape can be formed into a scrolled
tubular structure by heating due to differential shrinkage between
the right side and the wrong side. However, while the circular
knitted tubular structure A is being manufactured, as is shown in
FIG. 10, both ends of a fabric tape in the width direction may come
close to each other and curve inward while pressing against each
other. Consequently, a double-crest circular knitted tubular
structure A' is formed. In this case, the fabric tape may be formed
into a scrolled shape by placing one end on the other. However, a
curving force may be weaker than is expected, in which case the
self-closing function may become poor or an overlap portion may be
formed insufficiently. In view of the foregoing, it is preferable
for a manufacturing method of the present invention to forcedly
scroll the circular knitted fabric by using a conical shape-forming
induction jig having a circular opening at an inlet and a scrolled,
tapered opening at an outlet as will be described below.
[0075] FIG. 11 is a schematic view showing an example of a
manufacturing device of a circular knitted tubular structure. A
manufacturing device D of a circular knitted tubular structure
includes a furnace 30 heating the fabric tape 10 formed of circular
knitted fabric, and a shape-forming induction jig 20 provided
inside the furnace 30 and forming a shape of the fabric tape 10
into a scrolled shape. The shape of the fabric tape 10 is formed
into a scrolled shape with one end overlapping the other by the
shape-forming induction jig 20. As the fabric tape 10 is heated in
the furnace 30 while passing through the shape-forming induction
jig 20, high shrinkage back yarn in the fabric tape 10 undergoes
heat shrinkage and the circular knitted tubular structure A formed
into a scrolled shape remains scrolled. The circular knitted
tubular structures A and 1A each remaining scrolled as are shown,
respectively, in FIG. 4 and FIG. 5 are thus completed.
[0076] As is shown in FIG. 12, the shape-forming induction jig 20
is formed by scrolling a flat plate into a conical shape. An
opening at the inlet where the fabric tape 10 is inserted is
provided as a large circular opening 21 because the fabric tape 10
is in a flat state. An opening at the outlet is a scrolled, tapered
opening 22 because the fabric tape 10 is deformed into a scrolled
shape. By inserting the fabric tape 10 from the opening 21 at the
inlet of the shape-forming induction jig 20 for the right side to
form a scrolled inner peripheral surface while pinching part of the
fabric tape 10 in a scrolled overlap portion of the opening 21 and
pulling out the fabric tape 10 from the tapered scrolled opening 22
at the outlet, a shape of the flat fabric tape 10 is forcedly
formed into a scrolled shape with one end overlapping the other. A
circular shape of the opening 21 at the inlet is not limited to a
shape of a true circle and also includes a shape of an ellipse.
Shape-Forming Condition
[0077] The following will describe an example of concrete
shape-forming conditions using the manufacturing device. By heating
the fabric tape 10 at 70 to 190.degree. C. in a range within which
the fabric tape 10 becomes 0.8 to 1.3 times as long as the original
length in the length direction while the fabric tape 10 is passed
through the shape-forming induction jig 20 shown in FIG. 12 to let
the heat shrinkage yarn undergo heat shrinkage, the fabric tape 10
is curved into a scrolled shape with one end overlapping the other.
The circular knitted tubular structure A with the overlap portion
circumferentially overlapping 1.3 to 2.5 times is thus
manufactured. Herein, a range within which the fabric tape 10
becomes 0.8 to 1.3 times longer than the original length of the
fabric tape 10 means a range from a numerical value of the fabric
tape 10 that is shrunken when pushed into the shape-forming
induction jig 20 to a numerical value of the fabric tape 10 that is
stretched when pulled out from the shape-forming induction jig 20
while the fabric tape 10 is passed through the shape-forming
induction jig 20.
EXAMPLES
[0078] The following will describe the present invention concretely
by way of examples and a comparative example. It should be
appreciated, however, that the present invention is not limited to
the examples below. Respective physical values used in the present
invention are measured as follows.
Total Fineness of Yarn (dtex)
[0079] A total fineness of yarn is measured by a fineness based on
corrected mass in accordance with JIS L1013 8.3.1.
The Number of Filaments
[0080] The number of filaments is measured by the number of
filaments in accordance with JIS L1013 8.5.1.
Single Yarn Fineness (dtex)
[0081] A fineness of monofilament (single yarn fineness) in yarn is
found from a total fineness and the number of filaments measured as
above.
single yarn fineness (dtex)=total fineness/the number of
filaments
Dry Heating Shrinkage Ratio (%) of Yarn
[0082] A length of a sample, L1 (mm), under a load of 1/27 g/dtex
is measured. Subsequently, the load is removed and the sample is
placed in a drying machine and dried for 30 minutes at 160.degree.
C. The dried sample is allowed to cool to room temperature and a
length L2 (mm) is measured again under a load of 1/30 g/dtex. A dry
heating shrinkage ratio at 160.degree. C. is calculated by
substituting L1 and L2 into an equation as below. A measured value
used herein is an average value found by performing the measurement
five times.
dry heating shrinkage ratio(%)=[(L1-L2)/L1].times.100
Density of Knitted Fabric (Stiches/2.54 cm)
[0083] Density of knitted fabric is measured by density of knitted
fabric in accordance with JIS L1096 8.6.2.
Thickness
[0084] A thickness is measured by a thickness measured by the
method in accordance with JIS L1096 8.4B.
Mass Per Unit Area of Knitted Fabric (g/m.sup.2) and Mass Per Unit
Area of Tubular Structure (g/m)
[0085] A mass per unit area of knitted fabric is measured by a mass
per unit area measured by the method in accordance with JIS L1096
8.3B. A mass of a tubular structure per meter is measured and a
mass per unit length is used as a mass per unit area of the tubular
structure.
Ease of Fray from Cut Edge of Tubular Structure
[0086] Ease of fray from a cut edge (lateral side of the tubular
structure) in the length direction of the tubular structure is
measured by the method in accordance with JIS L1096 8.19.4D
(measurement in acceleration) which is a wear resistance measuring
method. A tubular structure is cut into a 10-cm-long piece in the
length direction. An entire edge of the cut piece except for 5 mm
from the cut edge in the length direction is fixed by bonding so as
not to fray during a test. No adhesive is applied to the cut edge
(lateral side of the tubular structure) where ease of fray is
measured. The cut piece is ironed at a temperature low enough not
to melt a fiber material forming the tubular structure to flatten
the tubular structure of a scrolled shape. A measuring sample is
thus prepared.
[0087] FIGS. 13A and 13B show an accelerated wear testing machine E
used to confirm ease of fray. In FIGS. 13A and 13B, a letter a
denotes a metal rotary blade, a letter b denotes a cylinder, a
letter c denotes a rubber film, a letter d denotes a glass plate,
and a letter e denotes a lid. Normally, abrasive paper is laminated
on an inner peripheral surface of the cylinder b forming the
testing machine E. However, the rubber film c with projections and
depressions as are shown in FIGS. 15 and 16 is used instead of
abrasive paper in this testing machine. The rubber film c is formed
of a rubber material having a length of 43.5 cm which is same as an
inner peripheral length of the cylinder b, a depth of 7.0 cm which
is same as a depth of the cylinder, a thickness of 0.35 cm (a gap h
between the projections and the depressions is 0.2 cm), a rubber
hardness of 82 to 83A, and a mass of 125 g.+-.1 g. In the testing
machine E, the measuring sample is pinched under the rotary blade a
and the measuring sample is rotated in suspension within the
cylinder by rotating the rotary blade a for two minutes at a
rotation speed of 2000 revolutions per minute. Subsequently, the
measuring sample is removed from the cylinder and the number of
strands of yarn frayed from the cut edge in the length direction is
counted. A strand frayed by half the length or more of the cut edge
of the measuring sample is counted as a frayed strand. The
measuring sample is evaluated as a failure unless there is no
frayed stand.
Bendability of Tubular Structure
[0088] Bendability of the tubular structure is evaluated by forming
a tubular structure into a ring by connecting both ends in circle
and checking whether an angular bent portion is created on the
inner periphery. A tubular structure formed into a smaller circle
and creating no bent portion has more excellent bendability.
[0089] (1) An evaluation tubular structure is cut in a length of a
desired inner peripheral length plus an allowance of 10 mm.
[0090] Evaluation rings having six different diameters (mm)
(circumferential lengths (mm)) as follows are prepared. Diameters
and circumferential lengths are based on inner diameters of the
rings.
[0091] Diameters (circumferential lengths): 100 (314), 75 (236),
50(53) 30 (94), 15 (47), and 10(31).
[0092] (2) A method of preparing a sample will now be described in
detail. For example, in a case where a ring having an inner
diameter of 100 mm is formed, the tubular structure is cut into a
length of 314 mm plus an allowance of 10 mm=324 mm. The allowance
is overlapped on a circle having the inner diameter to prevent the
circle from being deformed in the allowance. The allowance is
stitched together at a center of the tubular structure along the
circumference by a sewing machine by lock stitch at a pitch of 1
mm. An evaluation sample is thus prepared.
[0093] (3) The evaluation sample allowed to stand on a horizontal
desk is viewed from directly above and evaluated according to
criteria as follows.
[0094] According to the following evaluation criteria, an
evaluation sample ranked at 5 to 3 passes the test and an
evaluation sample ranked at 2 or 1 fails the test.
[0095] 5: the shape is substantially perfect circular shape and no
wrinkle and crease are confirmed.
[0096] 4: the shape is a substantially perfect circular shape and a
wrinkle is confirmed at one or more than one point on the inner
peripheral surface of the circle
[0097] 3: a large number of wrinkles are confirmed on the inner
peripheral surface of the circle
[0098] 2: the shape is an imperfect circular shape and creases are
confirmed at several points on the inner peripheral surface
[0099] 1: a large number of angular v-shaped creases are generated
and hence the shape is deformed into a polygonal shape
Example 1
[0100] A single circular knitting machine available from Precision
Fukuhara Works, Ltd. (VX-JS3, diameter: 30 inches, and gauge: 22G)
is used. Front yarn used is double-heater false twisted textured
yarn (dry heating shrinkage ratio: 3%) of 48 polyethylene
terephthalate filament at 167 dtex. Insertion yarn used on the
wrong side is polypropylene monofilament at 670 dtex having a dry
heating shrinkage ratio of 30% (large size, high shrinkage yarn).
Fabric is knitted by inserting one strand of insertion yarn into
two stands of front yarn according to a ratio of a structure in the
weave diagram of FIG. 3. Density of the resulting knitted fabric is
50 stitches/2.54 cm in the course direction and 44 stiches/2.54 cm
in the wale direction. A thickness and a mass per unit area of the
knitted fabric are 0.60 mm and 140 g/m.sup.2, respectively. As to a
material mixing ratio, polyethylene terephthalate accounts for 67%
and polypropylene accounts for 33%.
[0101] The knitted fabric is opened and cut like a slit in the
length direction by using scissors. An 8-cm-wide fabric tape is
thus produced. By subjecting the fabric tape to heat shape-forming
processing for two minutes at a preset temperature of 170.degree.
C. in the hot-air drying machine by using the shape-forming
induction jig described above, a width of the fabric tape is
reduced by shrinkage and the insertion yarn on the wrong side
shrinks. A tubular structure having a diameter of 1 cm and an
overlap portion circumferentially overlapping 1.7 times is thus
manufactured.
Example 2
[0102] A double circular knitting machine available from Precision
Fukuhara Works, Ltd. (V-LPJ4, diameter: 30 inches, and gauge: 20G)
is used. Front yarn used on the cylinder side of the knitting
machine is false twisted textured yarn of 48 filament at 167 dtex
and having a dry heating shrinkage ratio of 3%, that is, yarn same
as the front yarn used in Example 1 above. Back yarn used on the
dial side of the knitting machine is polypropylene monofilament at
220 dtex having a dry heating shrinkage ratio of 30% and false
twisted textured yarn at 167 dtex same as the front yarn. Fabric is
knitted by interlock knitting according to the weave diagram of
FIG. 6 by changing the back yarns alternately. Density of the
resulting knitted fabric is 48 stitches/inch in the course
direction and 26 stitches/inch in the wale direction. A thickness
and a mass per unit area of the knitted fabric are 1.2 mm and 250
g/m.sup.2, respectively. The knitted fabric is cut in the same
manner as in Example 1 above and an 8-cm wide fabric tape is
produced. In the fabric tape, polyethylene terephthalate accounts
for 70% and polypropylene accounts for 30%.
[0103] By subjecting the fabric tape to heat shape-forming
processing for two minutes at a preset temperature of 170.degree.
C. in the hot-air drying machine by using the shape-forming
induction jig described above, a width of the fabric tape is
reduced by shrinkage and the back yarns on the wrong side shrink. A
tubular structure having a diameter of 1 cm and an overlap portion
circumferentially overlapping 1.7 times is thus manufactured.
Comparative Example 1
[0104] The following will describe a tubular structure formed of
woven fabric by way of example as Comparative Example 1.
[0105] A warp used is mono-heater false twisted textured yarn
(black spun-dyed yarn having a dry heating shrinkage ratio of 3%)
formed by warping fiber of 48 polyethylene terephthalate filament
at 167 dtex. A weft used is polypropylene monofilament (black
spun-dyed yarn) at 660 dtex having a dry heating shrinkage ratio of
30%. By weaving the warp and the weft with a rapier loom available
from Ishikawa Seisakusho, LTD, woven fabric of 3/1 right twill
weave having density in gray fabric of 38 warp strands/2.5 cm and
25 weft strands/2.5 cm and a woven width of 100 cm is manufactured.
The woven fabric is cut with heat along a warp by using flat
soldering iron and a ruler. An 8-cm-wide fabric tape with the both
side surfaces made fray-proof by heat cutting is thus
manufactured.
[0106] The fabric tape is heated by using the shape-forming
induction jig described above by same operations under same
processing conditions and formed into a tubular structure. The
tubular structure thus obtained has a diameter of 1 cm and an
overlap portion circumferentially overlapping 1.7 times.
[0107] The single circular knitted fabric (Example 1) and the
double circular knitted fabric (Example 2) formed as above have
stretching properties in circular knitted fabric in itself. Hence,
the tubular structure formed of the circular knitted fabric is
sufficiently pliable and has extremely excellent adaptability to
bending in comparison with a tubular structure formed of woven
fabric. As is shown in FIG. 16, a side cut portion of the tubular
structure of Example 1 ((a) in the drawing) does not fray at all in
the wear test according to "ease of fray in the cut edge of the
tubular structure" described above. On the contrary, an end face of
the woven fabric cut with heat in Comparative Example 1 ((b) in the
drawing) is hard and snags to a hand. As is shown in FIG. 16, fray
occurs markedly in the wear test.
[0108] Pliability to bending is evaluated in each of the tubular
structures of Example 1 and Comparative Example 1. Evaluation
results are set forth in Table 1 below and shown in FIG. 17 and
FIG. 18. Of circular shape evaluation samples in Comparative
Example, samples having inner diameters of 15 mm and 10 mm are not
evaluated because a sample having an inner diameter of 30 mm
already appears angular.
TABLE-US-00001 TABLE 1 Tube diameter Inner diameter value (mm) of
circle (mm) 200 150 100 75 50 30 15 10 Example 1 10 5 5 5 5 5 5 4 4
Comparative 10 5 5 4 3 2 1 1 1 Example 1
[0109] FIG. 17 is a picture showing a change in shape in Example 1
when an inner diameter is changed in six steps as in a row A: 100
mm (A1 in the drawing), 75 mm (A2 in the drawing), 50 mm (A3 in the
drawing), 30 mm (A4 in the drawing), 15 mm (A5 in the drawing), and
10 mm (A6 in the drawing), and a change in shape in Comparative
Example 1 when an inner diameter is changed in four steps as in a
row B: 100 mm (B1 in the drawing), 75 mm (B2 in the drawing), 50 mm
(B3 in the drawing), and 30 mm (B4 in the drawing). FIG. 18 is an
enlarged picture of the samples having inner diameters of 75 mm and
50 mm of Comparative Example 1 shown in FIG. 17, which shows that
tubular structures change markedly. In Comparative Example 1, many
wrinkles are confirmed on the inner peripheral surface of the
circle in the sample having an inner diameter of 75 mm (B2 in the
drawing) as are indicated by arrows, and wrinkles and creases are
confirmed at several points on the inner peripheral surface of the
circle of the sample having an inner diameter of 50 mm (B3 in the
drawing) as are indicated by arrows and a circular shape is
deformed.
REFERENCE SIGNS LIST
[0110] A: circular knitted tubular structure formed of single
circular knitted fabric [0111] 10: fabric tape [0112] 11: front
yarn forming front loops [0113] 12: back yarn having high heat
shrinkage ratio [0114] B: circular knitted tubular structure of
Comparative Example 1 [0115] C: circular knitted tubular structure
of Comparative Example 2 [0116] 1A: circular knitted tubular
structure formed of double circular knitted fabric [0117] 111:
front yarn forming front loops [0118] 112a: back yarn forming back
loops and having high heat shrinkage ratio [0119] 112b: back yarn
forming back loops [0120] 113: engaging yarn [0121] A':
double-crest circular knitted tubular structure [0122] 20:
shape-forming induction jig [0123] 21: flat opening [0124] 22:
scrolled opening [0125] D: manufacturing device of circular knitted
tubular structure [0126] 30: furnace [0127] E: accelerated wear
testing machine [0128] a: metal rotary blade [0129] b: cylinder
[0130] c: rubber film [0131] d: glass plate [0132] e: lid
* * * * *