Carding
Carding is a section where
individualization is done of fiber by various actions in a carding machine. It
is called the heart of spinning. The carding machine is set with hundreds of
fine wires that separate the fibers and pull them into somewhat parallel form.
A thin web of fiber is formed, and as it moves along, it passes through a
funnel-shaped device that produces a ropelike strand of parallel fibers.
Blending can take place by joining laps of different fibers. From carding
action sliver is formed.
Objectives
of Carding
► Opening & Individual fibers.
► Elimination of impurities and dust.
► Elimination of short fibers.
► Disentangling of neps.
► Fiber blending & Orientation.
► Sliver formation.
Carding
Machine Actions
A
machine for combing and paralleling fibers of cotton, flax, wool, etc., prior
to spinning to remove short, undesirable fibers and produce a sliver is the
carding machine.
1. Carding action between cylinder and flat.
Purpose
of the cylinder and flats are
i)
To card the fibers which
means to open the cotton, even
to the separation of one fibre from all the others (fibre to
fibre separation)
ii) To separate short fibers, dust and
dirt and collect outside the cylinder under casing through spacing of the under
grid. The wire points of flat oppose the direction of the cylinder wire point,
i.e. point vs. point wire system is placed between cylinder and Flat. Flat
slowly moves at the rate of 2.5 inches/min and rotates in the same direction of
cylinder, because of these reasons, carding action takes place between cylinder
end flats which means fiber to fiber separation is achieved. The flat gets full
charge of cotton as the flats come in to position over the cylinder.
2.
Heel and Toe arrangement
The wire surface of the flat is not
parallel to that of the cylinder. Wire
point setting between cylinder and flat is wider where the cotton enter and closed where the
cotton leave. This arrangement is called as heel and toe arrangement.
Object of heel and toe arrangement is to
achieve gradual carding action
at each flat. Necessity: When the cotton is carried forward from one flat to
another, the air current, centrifugal force, elasticity of fibre causes the
fibre to rise from the surface of cylinder. These raised fibres would be rather
severely dealt with if they were dragged into the narrow setting between
cylinder and flats. This suddenness action is avoided by heel & toe
arrangement.
3.
Cylinder arch and concentric bends.
On each side of the main cylinder, a
strong cast iron cylinder arch is fixed. Cylinder arches support the flats. On
cylinder arch, front concentric bend, back concentric bend and flexible
bend are assembled with
cylinder grinding and Front
plate encloses the space between
flat and doffer.
Back plate is filed on back
concentric bend. This encloses the space between flat and licker in.
4.
Flexible bend
On each side of the cylinder, a strong
cast iron cylinder arch is fixed. On cylinder arch, front concentric bend, back
concentric bend and flexible bend are mounted. Flexible bend supports the
flats. Flexible bend
is used to adjust and
correct the setting between flat and cylinder .Flexible
bend is provided one on each side of the card.This bend is not flexible but
their curvature can be altered, to correct the cylinder to flat setting. The
repeated grinding of the cylinder wire points need accurate adjustment
to set the flat as close
as 0.010.To get wider setting
between cylinder and flats, the lacking screw should be released first and then
by operating the circular nut the regulating screw is raised. The flexible bend will also be raised, carrying the flat away from
the cylinder. This will result in a wider setting between the flats and
cylinder. When the correct setting is obtained, locking screw is fully
tightened so that the position of flexible bend will be fixed till next
adjustment.
5.
Front plate or percentage plate
BEQ; what will happen if front plate
setting is adjusted How will you control the % of flat waste On each side of
the cylinder, a strong cast iron cylinder arch is fixed. On cylinder arch,
front concentric bend, back concentric bend, flexible bend are mounted. Front
concentric bend supports 3 pieces of front plate i) Top percentage plate
setting:
Upper edge-10 thou to 60 Thou (10 Thou
means 0.010 inch Lower edge-32 Thou. The object of this setting is to control
flat strips waste the flats are stripped when they have left the cylinder area
by an oscillating comb, and the strips hang at the front of the card like a
curtain, being connected together along their lengths by some fibres which
bridge from one strip to another. Top % plate setting is very important because
it control the thickness and weight of the flat strip. If this setting is too close- the flow of air
over the top edge and
between flat is so fast
and flats are
effectively stripped and flat
waste in the flat is
transferred to the cylinder again which causes poor web
buy results in lighter flat strips. If the
setting wider- flow of air round the
top edge is reduced
but, cotton is now moved from cylinder Wires to
flats, bridging them with them
with good cotton, i.e. good material is lost as flat strip waste. The best setting is that strip should barely
hold together by bridging fibres as
they are stripped at the front of the* card. Middle plate
provides access to the
cylinder wire for stripping and grinding.
6.
Back plate
Back
plate is fixed on back
concentric bend. This plate encloses the space between flats and
licker in. The object of the back
plate is to hold the fibres on cylinder wire and to prevent undesirable air current.
Setting: Upper edge- 0.010" Lower
edge-0.012" Wider setting causes
cloady web due to uneven distribution
of fibre across the cylinder because of the
uncontrolled air current.
7.
Cylinder under casing.
The objects of cylinder under casing are: i)
To hold the good fibres on the cylinder ii) To permit the short fibres, dust,
dirt particles to fall down and collect
outside the cylinder grid through spacing
of under casing.
Settings: Back 0.012
“Middle - 0.032" Front:
0.064" This setting influences air
current and production of fly.
Wider setting causes loss of fibres. The setting is wider at front because, here the
cotton first makes contact with under casing
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