Blowroom

Chapter 2
The Blowroom

Prof.Dr. A.Kirecci - TE 211 Yarn Man. I 1

BLOOWROOM - PRODUCT OVERVIEW

Mixer

Fine Cleaners

Pre-cleaner

Bale Opener



Mixer

Mixer

Pre-cleaner
Pre-cleaner

Mixer

Fine Cleaner

Bale Opener



From Blowroom: Pre-cleaner, Fine Cleaner

Mixing Opener
Mixer
Pre-cleaner Dosage Blender

Mixing Bale Opener Pre-cleaner

Fine Cleaner
Bale Opener


Short-staple Spinning
Blowroom

Carding

Drawing

Roving frame

Ring frame

A typical process-line for ring spinning system


The Blowroom
The blowrooom is the first step of yarn production in the spinning mills.
Bales are taken to the blowroom and prepared for the process. Briefly,
basic operations in the blowroom are,
1) Opening
2) Cleaning
3) Dust removal
4) Blending
5) Even feed of material to the card

RIETER BLOOWROOM - PRODUCT OVERVIEW

Dosage blender

Bale opener Mixer

Pre-cleaner Fine cleaner


OPENING
Opening is the first operation within the blowroom in which the goal is always a high
degree of openness of material with gentle treatment and a fiber loss as less as
possible.


OPENING

Type of Opening and Degree of Opening
Two stages of opening must be distinguished.
I. Opening to flocks: in the blowing room.
2. Opening to fibers: in the card and OE spinning machine.

Ways of opening:
1) Breaking up of larger tufts into several smaller tufts to create new surfaces,
2) Opening up of individual tufts to increase the volume.


OPENING
The influence of a fourth or fifth cleaning step in the Hue on the over-all cleaning
efficiency is marginal, but the contribution to fiber loss and quality reduction is
considerably higher.

Hence short cleaning lines with only two or three cleaning points are today’s state-
of-the-art. With appropriate machinery design, one pre-cleaner and one or two fine-
cleaners per line are sufficient.


Opening Devices
Type Appearance Description

Small diameter,widely
Rollers
used, e.g. in step
cleaners.

Larger diameter,little used,
Drums
e.g. in mono-cylinder
cleaners.

Quilted shaft Shaft with many beater
rods,hardly used.


Opening Devices
Type Appearance Description

Multiple-bladed beaters Two, three, or more arms.
Now used only in old lines.

Endless belts with transverse
Spiked lattice wooden or plastics bars in
which needles are set, gives
very gentle opening.

Carding bars or plates The devices associated with
carding drums of the card.


CLEANING
The cleaning efficiency always has to be optimized and not maximized, since the
fiber quality (short fibers, neps) as well as fiber loss is always negatively affected
by maximum trash removal.


Deduction of Cleanability of Cotton

Ginning method Roller Saw

Appearance In layers, flocs felty, wadding
Seed- coat fragments a few many
Trash content high low
Size of particles big small
Neppiness low high
Cleanabitity very good-good bad-very bad


CLEANING
Cotton contains up to 18% trash; in most cases, this figure lies
between 1% and 7%.

To clean the material adequately, it is unavoidable to remove at
least as much fiber as waste. Since this loss is a considerable cost
factor, it has to be kept as low as possible, which requires an
assessment.

Cleaning Degree (CD ) =extracted trash * 100
trash content in infed cotton
Example :
extracted trash: 2.8% CD = 2.8*100/4 = 70%
trash in the bales: 4.0%,


CLEANING
extracted trash • 100
Cleaning Efficency (CE ) =
(parameter of fiber loss)
Total extracted waste

Fiber stressing index
(S1 ) = (Short fiber content output-Short fiber content input)*100
Short fiber content input


DUST REMOVAL
An often underestimated task of the blowroom line is the removal of dust.
However, it is as important as the removal of impurities.

Dedusting in the blowroom happens by air suctioning only, either
between the machines, e.g. by dust cages, dust extractors , etc., or within
the machine by normal air separation.

Every blowroom machine must be capable of extracting dust, so that
special dedusting machines should be needed.

The efficiency depends not only on the devices but also on the size of the
flocks. The smaller the flocks, the higher is the efficiency.


BLENDING
Blending of fiber material is an essential preliminary in the production of a yarn.

Fibers can be blended at various stages of the process. These possibilities should
always be fully exploited, for example, by transverse doubling.

However, the starting process is one of the most important stages for blending, since
the components are still separate and therefore can be metered exactly and without
dependence upon random effects.

A well-assembled bale layout and even (and as far as possible, simultaneous)
extraction of fibers from all bales is therefore of paramount importance.


EVEN FEED OF MATERIAL TO THE CARD
Finally, the blowroom must ensure that raw material is evenly delivered to the
cards.
Previously, this was carried out by means of precisely weighed laps from the
scutcher, but automatic flock-feeding installations are now state of the art.
Whereas, in the introductory phase, such installations were subject to
problems regarding evenness of flock delivery, today they generally operate
well.


Quantity of Waste
Rieter indicates average quantities of waste (in %) in the spinning mills of
industrialized countries.

Machines Cotton (Length) Synthetic
1 in. 1 1/6 in. 1 1/8 in. 1 1/2 in. Fibers
Ringframe 1.5 2.2 2.7 3.0 2.2

Roving-frame 1 1 1 1 1
Drawframe
per passage 0.6 0.6 0.6 0.6 0.6
Comber 12 15 17 19 — —
Ribbon lap 1 1 1 1 —
Sliver lap 0.5 0.5 0.5 0.5 —
Card 5.0 3.8 3.1 2.8 0.6
Blowroom 6 5 4 3 0.5


Blending the waste
It will be apparent that raw fibers are usually
better than waste fibers because waste contains
processed and therefore stressed fibers.
Furthermore, since waste fibers experience
different numbers of machine passages, they differ
from each other in their characteristics.
For example, lap web is strongly compressed, but
waste from thread-break suction systems is barely
compressed at all.
Random and uncontrolled feeding of such fiber
material back into the normal spinning process is to
be avoided at all costs, since considerable count
variation will result together with quality variations.


General considerations regarding opening /
cleaning
The degree of cleaning cannot be better than the degree of opening. Dirt
can be removed practically only from surfaces.
New surfaces must therefore be created continuously.
The form of the opening machine must thus be adapted to the degree of
opening already achieved.
The opening devices should become continually finer, i.e. within the
blowroom line, a specific machine required at each position.
The degree of cleaning is linearly dependent upon the degree of
opening.
Newly exposed surfaces should as far as possible be cleaned
immediately.
Ideally the opening and cleaning machines should form unit.


General considerations regarding opening/cleaning
A high degree of opening in the blowroom facilitates cleaning in the carding room.
A high degree of opening out in the blowroom reduces shortening of staple at the
cards.
Opening of cotton on only one opening machine is unthinkable owing to the
degree of opening required.
On the other hand, each machine in the line represent often considerable
stressing of the fibers.
Feeding of flocks in a clamped condition gives an intensive but usually not very
gentle opening action.
Feeding in a loose condition gives gentle, but not very intensive, opening.
Opened flocks should approach as closely as possible a spherical shape. Long
narrow flocks lead to entanglements during rolling movements and pneumatic
transport. Finally, they form neps.
Narrow setting of the feed device relative to the roller increases the degree of
opening, but also the stressing of the material.


BLOWROOM MACHINERY

Since blowroom machines have to fulfill various functions, they vary in
concept and in design. Basically, five types can be distinguished:

1. Opening machines.
2. Mixing machines.
3. Cleaning machines.
4. Dust-removing equipment or machines.
5. Recycling machines.


In order to be able to perform their assigned tasks optimally, these
machines must be located at quite specific positions in the blowroom line.

In a normal modem blowroom installation, 4-5 clearly distinguishable
operating zones can be identified

Bale Opening to finest flocks Zone-1 Machines

Pre-cleaning
no nipping: Zone-2 Machines
gentle treatment

Blending homogenous Zone-3 Machines

Fine cleaning
nipped: Zone-4 Machines
intensive treatment

*Fine cleaning II Zone-5 Machines

Rieter blowroom line

Dosage blender

Bale opener Mixer

Pre-cleaner Fine cleaner


If the cotton is clean and contains only few impurities, then only one
zone of fine cleaning is necessary.

Another variant is that fine cleaning and card feed can form a single
unit.

An additional operation in the blowroom - dust removal -should be
carried out by all machines in the line so as to make special
dedusting machines superfluous. But, if such machines are used,
they appear mostly at the end of the line.

Even when machines within an individual zone differ in design, they
are based on a common basic concept, so that all the machines of a
given zone can in general, be explained by taking one of them as an
example.


Zone 1 Opening Machines
Automatic Bale-opening Machines
The first-generation automatic bale-opening machines were mostly
stationary. Only the bales were moved, either backwards and
forwards or in a circle.

The second-generation machines are of the travelling type , i.e. they
move past the bales of the layout and extract material from top to
bottom.


Automatic bale opening machine UNIfloc A 11 (Rieter)
Raw Material -Cotton and man-made fibers up to 65 mm.
Production400-1400 kğ/hProf.Dr. A.Kirecci - TE 211 Yarn Man. I 30

Bale Plucking Machine Model LA17/LA28(Lakshmi)

Twin Plucking Rollers with Grills

Automatic Turning of Head

Electronic Panel with PLC


Crossroll Bale Opener


Travelling machines have the advantage that more bales can be processed as
an over all unit (charge), and thus a better long-term blend is achieved.

It should be noted, however, that these machines extract material only in
batches, i.e. they can process only one, two, or at most three bales
simultaneously. If a long-term blend is to be achieved, then mixing machines
must be included downstream from the bale opener.

A bale layout can consist of up to 60 bales from between four and six different
origins, i.e. from four to six different types of bales per fiber blend. Intervening
spaces often have to be left between the individual bale groups so that the
extraction roller can be adapted to varying bale heights.


The machines are completely electronically controlled and extract material
from all bales evenly, independently of varying bale densities. The
machines of this first zone should be able to:

• extract material evenly from the bales;
• open the material gently;
• open up to the smallest flocks;
• form flocks of equal size;
• process as many bales as possible in a single charge;
• be universally applicable, i.e. easy to program;
• blend material right at the start of the process; and
• permit the putting together of a fiber blend from several components (fiber
origins).


Normal bale openers extract the material from the bales chargewise, i.e. a
certain number of bales are placed in front of the opener and then worked
off and replaced by a new charge of the same number of bales.

Some manufacturers (e.g., Trutzschler) now offer machines of a different
kind, i.e. for a continuous processing of the bales. With this method, the
plucking device of the bale opener is inclined and extracts the material in a
wedge-shaped manner.

The moment the bale at the lowest point of the wedge is completely
exhausted, a new bale at the other end is forwarded into the wedge. The
replacement of the bales goes on one by one continuously and
automatically. In this case, one has to make sure that the average quality
parameters of the blend remain constant.


BLENDOMAT BDT 020 (Trützschler)

Automatic bale openers
BLENDOMAT BDT019 and BLENDOMAT BDT020:
Fiber-saving, even opening

Production rates up to 1,500 kg/hr
Easy operation
Minimal maintenance
Universally applicable
Up to 3 bale groups at the same time
Up to 180 bales in the feed
Feeding up to 3 lines
Lot work-off or continuous bale supply
continuous bale supply
Process visualization

The unifloc of Rieter
In concept, this is currently the most widely used type of machine.
Machines similar to the UNIfloc are built by Marzoli (B 12), and Trützschler
(Blendomat) among others.

The Rieter UNIfloc enables up to 130 bales arranged per side as four
components (different bale types) per blend over a maximum layout length
of 50 m to be processed. The machine can process one or two blends
simultaneously. The production rate is normally up to 1400 kg/h.


The feed duct (D) and the two guide rails (5) are secured to the floor.

The chassis (A), which moves back and forth on the guide rails, carries a
turret (B), which is rotatable through 180° and supports a raisable and
lowerable extracting assembly (C).

The latter has individually replaceable double-tooth discs and changes its
direction of rotation on reversal of the direction of movement of the chassis,
so that material can be extracted in both directions of travel.


UNIFLOC


Zone 2 Machines Pre-cleaning

- they generally process the material while it is in free flight; and

- the striker elements are widely spaced on the operating rollers.

The opening effect is correspondingly small. This is acceptable in zone 2
because an adequate surface area has already been created before that
stage.


These machines are preceded by the bale-opening machines that
form small flocks and thus large surface areas.

The bale-opening machines-themselves cannot clean these surfaces
because they are not fitted with cleaning devices, or, where such
devices are present, they can eliminate only a fraction of the
impurities owing to the high material throughput.

In their basic design, pre-cleaning machines are optimal at their given
position in the line but not at other positions.


The Step Cleaner

The step cleaner is disappearing more and more from the market. In
this machine, the material falls into the feed hopper and passes to the
first beater.

From there, it is transported upwards by the six (sometimes four) beater
rollers, each carrying profiled bars; the beaters are arranged on a line
inclined upwards at 45°.


The elimination of impurities
takes place during the
continual passage of the
material over the grids
arranged under the rollers.

The grids are always
adjustable, and usually the
beater speed is also
adjustable.


Dual-roller cleaner

An example of the dual-roller cleaner is the B31/1 of Marzoli . Here
again, similar models are offered by other manufacturers. The
machine consists of a large cleaning chamber containing two
drums of 610-mm diameter rotating in the same direction.


A fan downstream from the dual-roller cleaner (e.g. in a condenser)
draws material through the machine by suction.

Owing to the larger size of the chamber in comparison with that of
the suction duct, the suction effect falls away in the chamber.

The exit opening is arranged at a higher level than the infeed
opening. Thus, only the smallest flocks can fly straight through.


Most flocks fall into the region of the drums, where, for purpose of
cleaning, they are fed either once or more frequently over the grid bars
before they can leave the machine. The spikes are arranged in a spiral
on the drums in order to improve the passage of the material.


Single roller cleaner

A large roller equipped with
specially designed pins guides
the raw material several times
over a set of grid bars between
entry and exit , which results in
a high cleaning efficiency.


The material passes
simultaneously through a dust-
extraction system, which results in
a high dedusting effect of the
machine.
The material-guidance system
within the machine is purely
mechanical and independent of the
transportation of air. A vacuum
system with a lock roller below the
machine automatically removes the
waste.

The machine excels in high cleaning efficiencies with the lowest fiber loss.

Zone 3 - Blending Machines

The Mixing Battery
This was once the most common type of mixing, and it is still used. The
mixing battery represents the conventional mode of mixing at the start of
the process, from two to five mixing bale openers operate together;
usually one of these openers is a waste feeder.

A good blend is obtained because each opener can be supplied with a
plurality of bales, and the opened material from all bale openers flows
together onto a common conveyor belt .


Crosrol Blender (4CB/6CB)

Mixing Bale Opener
Model LB ¾(Lakshmi)

Multiple Mixer
The machine consists of several (from six to eight) chute chambers into
which the material is blown from above.

The chutes are filled successively, and the material is removed from all
chutes simultaneously. This gives a good long-term blend.

Ejection of flocks onto a collecting conveyor is done by take-off and beating
rollers under the chutes. The filling height is held fairly constant by feelers.


Multi-mixer MPM 6

Multi-mixer MCM 6 with cleaner CLEANOMAT CXL

Machines were available with filling heights of 2, 3, and 4 m.

To increase the blending effect of normal chute blenders, some
manufacturers install two blenders in a line, mostly with a cleaning
machine positioned between both. For modern control systems,
these blenders often serve also as a material buffer.


UNImix of Rieter
The machine is made up of three parts: a storage section, an intermediate
chamber, and a delivery section.

Flocks are fed
pneumatically and
simultaneously into six J-
shaped chutes (2),
arranged one behind the
other in the storage
section.
A conveyor belt (3) leads
the stock through the
intermediate chamber to
the take-off unit. The
material columns are thus
diverted out of the vertical
into the horizontal.

Mixer UNImix B 70(Rieter)

Unimix
Model LB 7/3(Lakshmi)

Unimix


In addition to a condensing effect, this 90° bend in the material flow
also produces a shift in the timing and spatial distribution of transport
of the fiber packets from the first to the last chute.

This in turn results in
good long-term blending.
Thereafter, as in a
blending opener, material
is extracted from the
intermediate chamber
and subjected to a further
opening step between an
inclined spiked lattice (5)
and an evener roller (7),
giving an additional good
short-term blending.

An optical sensor ensures that only a small quantity of fiber stock is
held in the mixing chamber (6). After the spiked lattice, there is
either a simple pneumatic-suction feed to the next machine or a
cleaning unit. Both blending and cleaning machines are thus
provided in a single piece of equipment


BLOOWROOM – Dosage Blender

Yarn produced

with dosage blender


Zone 4 Fine Cleaning (I) machines
In contrast to the zone 2 machines, those of zone 4 have again to
produce new surfaces, i.e. the cleaning operation must be preceded
by opening.

Zone 4 machines therefore almost always operate with clamp feeds.
Bladed rollers, spiked rollers, or rollers fitted with a coarse saw-
tooth are generally used. These are often called horizontal openers
or cleaners.

Crosrol places in its horizontal opener (Three-roller Cleaner) three
bladed rollers behind each other in a horizontal line.

With a modern blowroom line, for many types of cotton the fine
cleaning line (I) is no longer required, only fine cleaning (II).


Horizontal Opener B34 of Marzoli
The machine is fed through a cage condenser. The feeding silo
(1) has an adjustable side to vary its capacity according to the
required production and the type of material to processed.

The material, whose level is
controlled by a photocell, is
conveyed through a pair of
grooved feeding rollers (2)
towards the nipping roller
and the feelers.


he speed of the feeding rollers is varied by means of the
potentiometer in order to ensure the constant high yield of the
machine in line with the requirement of the other machines in the
production sequence.

The opening-and-cleaning
box is equipped with a
beater (3) and a grid (4)
fitted with adjustable
blades.


The beater can be porcupine,
three-blade, or of the carding type,
and interchangeable in order to
guarantee maximum versatility for
every process requirement.

In the newly designed B35 cleaner,
the bladed beaters. (porcupine) are
replaced by sawtooth rollers and
the grid bars by knife blades with
carding segments between them.
Crosrol offers a horizontal cleaner
with three bladed beaters in a line.


Zone 5 Machines - Fine Cleaning II

In older installations, this zone was provided by the scutcher in the form
of a Kirschner beater and still may be even in modern lines without a
scutcher.

Alternatively, or possibly in addition to the Kirschner beater, there may be
a saw-tooth or needle roller.

This form of intensive-cleaning zone, with a carding or combing roller,
has been forced on spinners in the past, since cotton stock has become
steadily more contaminated, and the impurities have become
progressively smaller.

Where only one machine is used, the carding roller is preferred
to the Kirschner beater.

In this zone, machines from the individual manufacturers exhibit
many similarities.

Often, they are universal machines, which can be fitted with
different types of opening roller.

As a representative example, the Rieter cleaner will be
described.


Fine Cleaning and Dedusting
Machine UNIflex B 60R of
Rieter

This machine for the opening,
cleaning, and dedusting of
cotton.


Fine cleaner UNIflex B 60
Flexiclean
(Rieter)

A fan in the feeding duct helps to
supply the machine with its raw
material.

A specially designed flip-flop feeding
device (I) forms a homogeneous
wadding in the lamina chute (2) over
the whole length and width.

The dust-laden transport air is
extracted through the lamina chute.
The adjustable depth of the chute
allows for a homogeneous filling
operation to take place according to
the production requirements.


Two drums (3) positioned at the bottom
of the chute extract the material.

One of them is perforated (4) to allow
for additional dedusting. The feeding
roller (5) and the servomotor- controlled
adjustable feeding plate pass the fibers
on to the opening and cleaning unit (6).

By using the operating panel (7), the
nipping point can be adjusted according
to the staple length of the material.


The opening-and-cleaning
cylinder (6) guides the fibers
over a modular grid consisting
of servomotor-adjustable mote
knives (8), and one or two
carding elements. It separates
the rest of the trash intensively
but gently from the material.

The angle of mote knives is also
adjusted through the operating
panel.


By adapting the speed of opening and cleaning rollers, operation
can be adjusted to optimal demands. The clothing of the drum is
adaptable to the required performance.

Adjustments are made via the ‘cleaning-parameter’ field, menu-
driven by using a display and keyboard. The ‘cleaning intensity’
alters the nipping point and the speed of the opening-and-cleaning
cylinder. By using the ‘amount-of-waste’ field is opened or closed.


The Components of Blowroom Machines

Feed Apparatus

Feed of material to the opening rollers occurs in free flight (gentle but less
intensive treatment of the fibers) or in a clamped condition (intensive but
less gentle treatment).

Free flight requires only a drop chute, suction pipe, or vortex transport from
rollers; a clamped-feed condition demands special machine components.

Basically, feed devices can be distinguished according to whether they
consist of: two co-operating clamping cylinders; a feed roller and a feed
table; or a feed roller and pedals.


Operating with two clamping cylinders gives the best forwarding
motion, but unfortunately also the greatest clamping distance (a)
between the cylinders and the beating elements.

a

In a device having a feed roller and a table, the clamping distance a can be
made very small. This gives intensive opening.

However, clamping over the entire width is poor since the roller presses
only on the highest points of the wadding.

Thin places in the web can be dragged out of the wadding as a clump by
the beaters.

a

Where pedals are used, the table is divided into many sections, each
of which individually presses the web against the roller, e.g. via spring
pressure. This gives secure clamping with a small clamping distance
a.

As far as the feed system is concerned, influence can be exerted on
opening and cleaning only via the type of clamping, mainly via the
clamping distance (a) to the opening element.


Opening Devices

The great majority of operating devices in blowroom machines
function as opening devices.

Only in co-operation with cleaning apparatus such as grids, etc.,
can they be made to function as cleaning units.

Consequently, they are designed to operated in both opening and
cleaning machines.

Opening units can be classified as:

endless-path; gripping; rotating assemblies.

Depending on their design, construction, adjustment, etc., these
assemblies exert enormous influence on the whole process.


Endless-path Devices (Spiked Lattices)

Spiked lattices serve as forwarding and opening devices in bale
openers and hopper feeders.

They consist of circulating endless hoses or belts with transverse
bars at short intervals.

The bars are of wood or plastics; steel spikes are set into the bars
at a special angle and at greater or smaller spacing.


Owing to their disposition, inclined lattices usually feed the material
upwards at an angle.

The material is carried along by the spikes penetrating into the raw
material.

Opening is obtained because in the upper region of the lattice there
is a counter-rotating roller, also clothed with spikes and located
fairly close to the lattice.

This roller strips the material from the inclined lattice.


The counter-operation of the two systems of spikes causes the
flocks to be plucked apart.

The intensity of the opening action is dependent upon:

- the distance between the devices;

- speed relationships;

- the total working surface;

- and the number of points.


Spiked lattices are usually located in hoppers.

Since only a small part of the material — the smaller flocks — can
pass between the very closely spaced spike systems, the greater
part is continually thrown back into the hopper, and this has both
positive and negative effects.

On the one hand, the rotation leads to thorough mixing; on the
other, neps are formed.

Both effects become more marked as the quantity of material in the
hopper increases.


Rotating Devices
I-Rollers with Teeth (Blades) or Spikes

Short, flat, oval, or round iron pegs are welded, riveted or screwed on
the surface of short cylinders.

Flat and oval pegs are secured with the narrow side facing the
direction of rotation.

Various spacing of the striker elements are used.


These devices are incorporated mainly in modem horizontal cleaners,
chute feeds, mixing bale openers, step cleaners, etc., which are located
from the beginning to the middle of the blowroom line.

At the start of the line, the spacing of the striker elements on the roller is
greater; finer spacings are used in the middle (to the end) of the line.

The rollers rotate at speeds in the range of 600-1000 r/min.


II-Drums with Teeth, Small Blades, or Spikes

The cylindrical parts are similar to those of the spiked rollers, but they have
larger diameters of 600 mm and more.

The striking elements are mostly of the same type, though they may differ.

In several designs, shafts carrying discs are used in place of cylindrical
bodies (porcupine drum).


On their outer peripheries, the discs carry striker noses in the form of
welded or riveted flat bars. The discs are maintained at the desired spacing
by intervening collars.

In all opening assemblies, it is important to avoid removal of material from
the feed batt in strips. For this purpose, the teeth or spikes are usually
staggered to varying degrees.


The spacing of the striker elements on the drums is coarse when the
drum is designed for use at the start of the process (the Rieter UNIclean,
for example) and fine when the drum is designed for use in the middle or
towards the end of the line (for example, as a porcupine cleaner).

Rotation rates range between 400 and 800 r/min, and the device can be
arranged parallel to or at right angles to the material flow.


III-Rollers with Toothed Discs
In contrast to spiked rollers or drums, which have quadrilateral or round
elements, toothed-disc units have noses triangular plucking elements
(coarse sawteeth).

The complete opening device is made up of many such toothed discs
secured to a shaft with an appropriate number of distance pieces. In
this case also, the removal of material in strips is to be avoided.

In toothed discs, the teeth are almost always asymmetrically formed,
since they have to operate in only one direction and therefore rotate in
only one sense.


Automatic bale-opening machines often require alternative
arrangements, since in many cases they move backwards and that is,
the directions of movement and of removal of the material vary.
The material-extracting roller should be sometimes in one direction
and sometimes in the other.
If only one roller is to be used, then it must have symmetrical teeth
that are effective in both directions. This requirement can be satisfied
if the elements are formed as double teeth.(Rieter Unifloc).
Rollers with toothed discs belong in the middle of the blowroom line,
except for those included in bale openers.


IV-Sawtooth Rollers
The impurities have become steadily smaller owing to hard ginning.
If the machine is to eliminate even the smallest particles, then more
flock surface must be created, i.e. the material must be opened to
substantially smaller flocks than before, which is, for that purpose

essential to use — sawtooth wire, for example.


However, this roller not only gives the finest opening and the best
cleaning, but it also stresses the fibers most strongly. Setting the speed
of rotation, and other adjustments, demands a ‘feel’ for the operation.

Rotational speeds lie between 600 and 1000 r/min. Sawtooth rollers are
used at the end of the line.


V-Needle Rollers, Pinned Rollers

When processing long-staple and extra-long-staple cottons, the
sawtooth rollers react very aggressively.

Rollers with needles or pins are being used to protect the fibers in
this case.

With medium-staple cottons having a low trash content, the
application of needle rollers is also possible.


Fully spiked roll

Needle roll


VI- Beater Arms (Multiple-bladed Beaters)
Multiple-bladed beaters consist mainly of two or three beater bars
arranged parallel to the supporting shaft and held there by four or
five cast-iron arms.

In the course of one rotation of the shaft, the web projecting from
the feed rollers is subjected to two or three blows over its whole
width. The opening effect, and hence the cleaning effect, is small.

This machine is hardly used today; when it is found at all, it is only
in the form of the double-beater scutcher.


VII-Beaters with Pinned or Needle Bars (Kirschner Beaters)

These machines are similar to the multiple-bladed beaters, but, instead
of beater bars, pinned bars (pinned lags) are secured to the ends of the
cast-iron arms.

The relatively high degree of penetration gives good opening.

Kirschner beaters are therefore often used at the last opening position in
the blowroom line, since good pre-opening of the fiber material enables
gentle opening to be achieved at the taker-in of the card.


The cleaning efficiency of the Kirschner beater is high, but unfortunately
fiber elimination is too hign.

Some machinery manufacturers have therefore replaced the grid under
the Kirschner beater with a guide plate; the resulting machine is an
opener, but no longer a cleaner.

Kirschner beaters comb through the web at speeds of 800—900 r/min.


The Grid

It is the grid or a grid-like structure under
the opening assembly that determines the
level of waste and its composition in
gums of impurities and good fibers.

Grids are segment-shaped devices under
the opening assemblies and consist of
several (or many) individual polygonal
bars or blades (i.e. elements with edges),
and together these form a trough.

The grid encircles at least a quarter, at
most three-quarters, and usually from a
third to a half of the opening assembly.


The grid has a large influence on
the cleaning effect via: the section
of the bars; the grasping effect of
the edges of the polygonal bars;
the setting angle of the bars
relative to the opening elements;
the width of the gaps between the
bars; and the over-all surface
area of the grid.


Elements used in the grids can be ;

• slotted sheets (a);
• perforated sheets (b);
• triangular section bars (c); b a
• angle bars (d);
• blades (e) (like mote knifes).

c d

e

Grid Adjustment

Three basic adjustments are possible
- distance of the complete grid to the beater;
- width of the gaps between the bars (a = closed, b = open); and

- setting angle relative to the beater envelope (c = aggressive, b = glancing).

a

b

c

It is seldom possible to make all three adjustments; the machines are
generally so designed that only two adjustment types are possible.

With carding segments, only the distance has to be changed.


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