Blowroom

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

Chapter 2

The Blowroom


Fine Cleaners

Bale Opener

Mixer

Pre-cleaner

BLOOWROOM - PRODUCT OVERVIEW


Fine Cleaner

Bale Opener

Pre-cleaner

Mixer

Mixer

Mixer

Pre-cleaner



Fine Cleaner

Bale Opener

Pre-cleaner

Dosage Blender

Mixing OpenerMixer

Mixing Bale Opener

Pre-cleaner

From Blowroom: Pre-cleaner, Fine Cleaner




Short-staple Spinning

Ring frame

Roving frame

Drawing

Carding

Blowroom

A typical process-line for ring spinning system


The BlowroomThe 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

Fine cleanerPre-cleaner

Dosage blender

MixerBale opener

RIETER BLOOWROOM - PRODUCT OVERVIEW


OPENINGOpening 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.


OPENINGThe 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

used, e.g. in step

cleaners.

Rollers

Larger diameter,little used,

e.g. in mono-cylinder

cleaners.

Drums

Shaft with many beater

rods,hardly used.Quilted shaft


Opening Devices

Type Appearance Description

Two, three, or more arms.

Now used only in old lines.Multiple-bladed beaters

Endless belts with transverse

wooden or plastics bars in

which needles are set, gives

very gentle opening.

Spiked lattice

The devices associated with

carding drums of the card.

Carding bars or plates


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 liesbetween 1% and 7%.

To clean the material adequately, it is unavoidable to remove atleast 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

Cleaning Efficency (CE ) =

(parameter of fiber loss)

extracted trash • 100

Total extracted waste

Fiber stressing index

(S1 ) =(Short fiber content output-Short fiber content input)

*100Short 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.


BLENDINGBlending 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 WasteRieter 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

to finest flocks

no nipping:

gentle treatment

homogenous

nipped:

intensive treatment

Zone-1 Machines

Zone-2 Machines

Zone-3 Machines

Zone-4 Machines

Zone-5 Machines*Fine cleaning II

Fine cleaning

Blending

Pre-cleaning

Bale Opening


Rieter blowroom line

Fine cleanerPre-cleaner

Dosage blender

MixerBale opener


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/h


Bale Plucking Machine Model LA17/LA28(Lakshmi)


Twin Plucking Rollers with Grills

Electronic Panel with PLC

Automatic Turning of Head


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 RieterIn 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


Yarn produced

with dosage blender

BLOOWROOM – 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.


Flexiclean


Fine cleaner UNIflex B 60

(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., theseassemblies 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 DevicesI-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 teeththat 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);

• angle bars (d);

• blades (e) (like mote knifes).

ab

dc

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.

Education

Blowroom