Transcript Document

Chapter Seven
Multi-ply Fabrics
7.1 Double fabrics
7.1.1 The concept of double Fabrics
7.1.2 The principles of double fabrics construction
7.1.3 Construction of double weave diagram.
7.1.1 Concept of double
Fabrics
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Double fabric consists of two layers which are woven one
above the other. This fabric contains two systems of warps,
and two systems of weft. This fabric can also be called
two-ply fabric. The upper layer is formed by interlacing
the face warp threads with the face weft threads, and the
lower layer by interlacing the back warp threads with the
back weft threads.
Applications:
(1) A tubular fabric can be formed by connecting both
weaves at the selvages.
(2) A double width cloth can be produced in conventional
looms by connecting one edge of the weaves.
(3) Stitching the double fabrics to form a thicker and
heavier fabric.
(4) The different materials can be used in each layer to
reduce the production cost.
(5) Form patterns by interchanging double fabrics.
7.1.2 The principles of double
fabrics construction
The principles of double-weave construction
are shown as following. See Fig. 7.1.
Fig.7.1 Double weave
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Fig. 7.1 shows a double fabric where face and back are all
plain weave.
Here, the Arabic 1, 2 represent face ends and picks, and
the RomanⅠ, Ⅱ represent back ends and picks.
The arrangement of face and back is 1:1, i.e. one face end,
one back end; one face pick, one back pick.
For making double fabric, the picks are in sequence.
When we fill the back pick, all the face ends must be
lifted up.
The principles
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Suppose the face ends are drawn in shafts 1
and 2, the back ends are drawn in shafts 3 and
4. The processes of the construction double
fabric are described as following.
Show Flash
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(1) First pick: This pick is face pick 1, and the entire
back ends must be lowered down. The shaft 1 is lifted
up. See Fig (A).
(2) Second pick: This pick is back pickⅠ, and all the
face ends must be up. The shafts 1,2 and 3 are
lifted up, and shaft 4 remains down. See Fig. (B)
(3) Third pick: This pick is face pick 2, and all the
back ends must be lowered down. The shaft 2 is
lifted up.
(4) Forth pick: This pick is back pickⅡ, and all the face
ends must be up. The shaft 1,2 and 4 are lifted up,
and shaft 3 down.
7.1.3 Construction of
double weave diagram.
To construct a double weave diagram, some
elementary factors should be determined first:
1)
Select the face weave and back weave.
2)
Determine the arrangement of face and back
in warp and weft directions.
3)
Meet the weaving machine.
1) Select the face weave
and back weave.
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Due to their relatively independence, the face
and back weaves can be same or not. But in
order to weave smoothly with a uniform warp
tension, the crimp of the two weaves should be
quite similar .
2)Determine the arrangement of
face and back in warp and weft
directions.
The ratio of face to back :
1 : 1, 2 : 2 and 2 : 1 are recommended.
3) Meet the weaving
machine.
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If the looms are multi-box in both sides, any
arrangement is possible. If the looms are multi-box
in single side, the weft arrangement m : n must
satisfy that: both m and n are even numbers.
Steps for the construction of
double weaves:
1) Select face and back weaves, and draw them.
2) Determine the arrangement m: n.
3) Calculate the double weave repeats.
4) Draw the outline of the repeat, and indicate the
number of each space.
5) Transfer both face and back weaves to the new
weave.
6) Lifters: all face ends are lifted when back picks
are inserted.
Example:
Construct a double weave: face and back weaves
are plain, arrangement m: n=1:1.
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Select face and back weaves, and draw them:
See Figures A and B
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The arrangement is given as 1:1
So, the new repeats can be obtained :
RO=4 Ry=4
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 Draw the outline of the weave of one repeat, and
indicate the number of each space. Fig. (C)
Transferring the weaves. Fig. (D)
Lifters:
The mark ○ should be added at the
intersections of face ends and
back picks. Fig (E)
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The longitudinal section
and cross section are shown
at Fig. 7.3 (F), (G).
The face ends are usually
drawn in the front shafts,
and divided drafts are
usually employed.
Home works:
Construct the following double weaves.
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(1) face weave 2/2↗ twill, back weave 2/2↗ twill,
arrangement 1:1.
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(2) face weave 2/2↗ twill, back weave 1/1↗ plain,
arrangement of face and back in both directions
are 2:1.