Spinning Process - Model Of Optimum Cotton Mixing

Mixing and blending of cotton fiber in blow room Mixing: If different grade of same fibers are kept together, then it is called mixing... Blow room consists of a number of m/c used in su

Physical properties of raw material (cotton):

Fibre Length:

Short staple 1 in or lessMedium staple 1 1/32- 1 1/8 in

Long staple 1 5/32- 1 3/8 in

Extra Long Staple 1 13/32 in above

Fibre Strength:

Pressley value Grading

93 & above Excellent

harvesting machines.

Flow chart of carded yarn:

Flow chart of combed yarn:

Mixing and blending of

cotton fiber in blow room

Mixing:

If different grade of same

fibers are kept together,

then it is called mixing

Model of optimum cotton mixing:

The program is written on the basis of principles

of linear programming The constraints of the

mixing used in the program are cotton fiber

minimum length in mm, strength in grams per

Tex, Micronaire value in a range, maximum

trash percentage, and price per kilogram of the

cotton Also some of the practical constrains are

considered while formulating the mixing like

maximum and minimum bales to be taken for

mixing from a lot

The software generated system is, in generally, known as Bale Management Some branded software are BIAS, Bale Manager

BLOW ROOM

Blow room:

Cotton fibre is compressed in a bale of 200 to 250

kg This highly compressed cotton firbe need to be

open at first as a part of yarn manufacturing And

there are 1.5% to 7% trash in cotton bale which is

also needed to be removed before further

processing This process of opening & cleaning is

knows as blow room process Blow room consists of

a number of m/c used in succession to open & clean

the cotton fibre to the required degree 40% to 70%

of total trash is removed in this section

Number of opening machines

Type of beater

Type of beating

Beater speed

Setting between feed roller and beater

Production rate of individual machine

Production rate of the entire line

Thickness of the feed web

Density of the feed web

Fibre micronaire

Size of the flocks in the feed

Type of clothing of the beater

Point density of clothing

Type of grid and grid settings

Air flow through the grid

Position of the machine in the sequence

Amount of trash in the material

Type of trash in the material

Temp and relative humidity in the blow room department

Process parameter in the blow room:

Objects of blow room process:

To open the compressed layer of bale of cotton or any staple fibres with minimum damage to the fibres

To remove the impurities like sand, seed, bits, neps & short fibres present in the cotton with minimum loss of lint by opening & blending

To effect a through blending with minimum neps formation

To convert the mass of cotton fibres into a uniform thick sheet of cotton both longitudinally & transversely & fed as it in the case of chute feed system or wound

in the form of a compactly built lap with minimum lap rejection

Intensive de-dusting of cotton fibres to extract micro- dust in order to improve the working of opened spinning m/c

Fibre recovery from the waste produced by the various processes during the conversion of fibre to yarn in order to reduce the consumption of raw material

Technological performance of a blow room line and influencing factors

Opening: The first operation required in the blowroom line is opening Tuft weight can be reduced to about 0,1 mg in the blowroom The figure indicate that the degree of opening changes along a blowroom line This line is a theoretical layout for study purposes only The flattening of the curve toward the end shows that the line is far too long It should end

somewhere at machine No 3 or (at least) No 4 The small improvements by each of the subsequent machines are obtained only by considerable additional effort, stressing of the material, unnecessary fiber loss and a striking increase in neppiness

Openness of the fiber material after the various blowroom machine stages; axis A: Degree of opening (specific

volume); axis B: Blowroom stages

Basic operation in blow room:

Cleaning: A blowroom installation removes

approximately 40 - 70% of the impurities The result is

dependent on the raw material, the machines and the

environmental conditions The diagram by illustrates

the dependence of cleaning on raw material type, in

this case on the level of impurities.

Figure: Degree of cleaning (A) as a function of the trash content (B) of the raw material in %

The cleaning effect is a matter of adjustment It is shown

in bottom figure that, increasing the degree of cleaning

also increases the negative effect on cotton when trying

to improve cleaning by intensifying the operation, and

this occurs mostly exponentially Therefore each

machine in the line has an optimum range of treatment

It is essential to know this range and to operate within it

Figure: Operational efficiency and side effects

Normally, fibers represent about 40 - 60% of blowroom

waste Since the proportion of fibers in waste differs from one

machine to another, and can be strongly influenced, the fiber

loss at each machine should be known It can be expressed

as a percentage of good fiber loss in relation to total material

eliminated, i.e in cleaning efficiency (CE):

AT = total waste (%); AF = good fibers eliminated (%)

For example, if AT = 2.1% and AF = 0.65%:

Almost all manufacturers of blowroom

machinery now offer dust-removing

machines or equipment in addition to

opening and cleaning machines

Dust removal is not an easy operation,

since the dust particles are completely

enclosed within the flocks and hence are

held back during suction

It is mainly the suction units that remove

dust (in this example 64%), dust removal

will be more intensive the smaller the

tufts

It follows that dust elimination takes

place at all stages of the spinning

process as shown in figure

Dust Removal:

Fig 5 – Dust removal as a percentage of the dust content of the raw cotton (A) at the various processing stages (B): 1 - 5, blowroom machines; 6, card; 7, draw frames; (a) filter deposit; (b) licker-in deposit; I, dust in the waste; II, dust in the exhaust air.

intensive blending in a suitable blending machine

must be carried out after separate tuft extraction from

individual bales of the layout This blending operation

must collect the bunches of fibers arriving

sequentially from individual bales and mix them

thoroughly Multi mixer is the machine of blow room

where the uniform blending is carried out

Figure – Sandwich blending of raw material components

In conventional machineries, lap blending was the most significant one doubling scutcher is

required in this case; this has a conveyor lattice on which four to six laps (L) could be laid and

jointly rolled-off Lap blending produces very good transverse blends and also a good longitudinal blend,

Figure – Lap blending on an old scutcher

Even feed of material of the card:

Finally the blow room 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 increasingly being used While in the introductory phase such installations were subject to problem regarding evenness of flock deliver, today they generally operate well or at least adequately.

Introduction of blow room line:

Figure – Rieter blowroom line; 1 Bale opener UNIfloc A11; 2 Pre-cleaner UNIclean B 12; 3 Homogenous mixer UNImix B 75; 4 Storage and feeding machine UNIstore A 78; 5 Condenser A 21; 6 Card C 60; 7 Sliver Coiler CBA 4

Components of the blow room machine:

Feeding Apparatus:

Feed to a beater with two clamping rollers

Feed with an upper roller and a bottom table

Feed with a roller and pedals

Operating with two clamping cylinders gives the best

forward motion, but unfortunately also the greatest

clamping distance (a) between the cylinders and the

beating elements

In a device with a feed roller and table the clamping distance (a) can be very small This results in intensive opening

Where pedals are used (Fig 12), the table is divided into many sections, each of which individually presses the web against the roller, e.g via spring pressure This provides secure clamping with a small clamping distance (a).

1 End less path device:

Spiked lattices is known as endless path device It

serves as forwarding and opening devices in bale

openers and hopper feeders They consist of

circulating, endless lattices or belts with transverse

bars at short intervals The bars are of wood or

aluminum; steel spikes are set into the bars at an

angle and at greater or lesser spacing

The intensity of the opening action is dependent upon:

the distance between the devices;

the speed ratios;

the total working surface;

the number of points.

2 Gripping elements (plucking spring):

Some manufacturers, for example former Schubert & Salzer and Trützschler, have used plucking springs for opening Two spring systems, facing each other like the jaws of a pair of tongs, are parted and dropped into the feed material and are then closed before being lifted clear They grasp the material like fingers This type of gripping is the most gentle of all methods of opening, but it produces mostly large to very large clumps of uneven size This type of opening device is therefore no longer used.

3 Rotating Devices (Roller with teeth, blades or spikes):

Flat, oval or round bars are welded, riveted or

screwed to closed cylinders

The rollers are therefore called spiked rollers Various

spacing of the striker elements are used These

devices are incorporated mainly in modern horizontal

cleaners, chute feeds, mixing bale openers, step

cleaners, etc., which are located from the start 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 spacing are

used in the middle (to the end) of the line The rollers

rotate at speeds in the range of 600 - 1 000 rpm.

The grid:

In the final analysis, it is the grid or a grid-like

structure under the opening assembly that

determines the level of waste and its

composition in terms 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 1/4, at

most 3/4 and usually 1/3 to 1/2 of the opening

assembly

The grid has a major 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;

the overall surface area of the grid.

Figure:Two-part grid

The following elements can be used in the grid:

•slotted sheets (a): poor cleaning;

•perforated sheets (b): poor cleaning;

•triangular section bars (c): the most widely used grid bars;

•angle bars (d): somewhat weak;

•blades (e): strong and effective

These elements can be used individually or in

combination

Modern grids are mostly made up of triangular

bars They are robust, easy to manipulate and

produce a good cleaning effect The same is

true of blade-grids

Blades have been used as grid elements for

a long time (the mote knife), almost always in

combination with triangular section bars

Grid adjustment:

Three basic adjustments:

•Distance of the complete grid from the beater;

• width of the gaps between the bars

(a=closed, b=open);

•setting angle relative to the beater envelope

Conventional Machine of Blow room line:

Bale breaker:

Opening is mainly emphasized in this machine rather cleaning

This machine is designed to take layer

of cotton directly taken from bale and tear them apart leaving the cotton

partially opened

Porcupine opener:

The cotton fed by the previous

opener is carried forward by the

feed lattice

16 circular disc are mounted on

the shaft of this opener 14 to

18 striker blades are riveted

alternatively on each circular

The beaters are arranged on a line inclined upward at 45°

Elimination of impurities takes place during the continual passage of the material over the grids arranged under the rollers

Air Jet cleaner:

Object of this cleaner is to

open and clean the cotton, but

this cleaning unit introduces

the idea of dirt separation from

cotton by air force

The function of the Kirschner

beater section is to open and

clean the cotton and prepare

the cotton for air jet section

The tuft of cotton from the kirschner beater section is entered in to the aero dynamic constricting duct

The air current from the booster fan carry the cotton toward the bend in the duct

The duct makes a sharp turn of about 120 degree

Axi flow Cleaner:

This is known as dual roller cleaner

This machine has two beaters having 6 to 8 rows of spikes with flattened edge which

perform cleaning action

Beater speed is 400-600 rpm

Material through entire length of first beater pass over the grid bars where trash is collected and comes in contact with second beater

universally and this can

be used with many

blends

Less economical as

compared to chute feed

system

Its function is to clean the

material and form a

uniform lap for card

Kirschner beater:

In this type of beater, instead of beater bars,

pinned bars (pinned lags) are secured to the

ends of the cast-iron arms

The relatively high degree of penetration

results in good opening Kirschner beaters

were therefore often used at the last

opening position in the blowroom line

Modern Kirschner openers are often

designed as closed rollers rather than

three-armed beater units The design is simpler

and the flow conditions are more favorable

Beaters with pinned bars

Rollers with pinned bars

Modern Blow room line

ABO= Automatic Bale OpenerCPC= Crosrol Pre-Cleaner

CBO= Crosrol Blending OpenerCFC= Crosrol Fine Cleaner

CDR= Crosrol Dust Removal

Trutzschler Blow room line:

1= Automatic Bale opener BLENDOMAT BO-A

2= TUFTOMAT SYSTEM

3= Metal Detector

4= Universal Mixture MX-U

5= SECURO PROOF SP-FPU

6= Universal Cleaner CP-U

Rieter Blow room line:

The UNIfloc A 11 processes the fiber material gently and

efficiently into microtufts, from which impurities can be

removed very readily in the subsequent processes

•The UNIfloc is designed for output of up to 1 400 kg/h (carded sliver)

•Bales are laid down over a length of 7.2 to 47.2 meters

•The UNIfloc can process up to 4 assortments

simultaneously

•The width of the take-off unit can be selected between 1 700

and 2 300 mm