BLOW ROOM
It is the most important and essential part of the spinning process which contain a series of machines and in this process following operation take place......
Bale Opening
We obtain the cotton after ginning from various stations in the form of compact structure of about 160 Kg (Approx) known as bale. Bale opener open the bale,At the very beginning, automatic feeding of cotton is generally accomplished by the use of a circular bale picker or a continuous rectangular bale opener. This picker or opener is designed to receive the layers of cotton directly from the bale and to break these layers into small lumps. To ensure evenness in blending, usually the lay-out of the cotton bales should have the same height level. Lying bales of material on a conveyor belt is a special idea on today’s continuous bale opener. |
| BALE OPENER ( BLENDOMATE BO-A) Main operation during Bale opening opening the tight and large tufts into smaller tufts for proper cleaning of the fibres and for better further operation. |
Cleaning
It is the second process of the blow room line the purpose of the cleaning machines is the opening of larger particles of cotton and the removal of large motes, pieces of trash, and other heavy foreign matter in the cotton. The main action of cleaning machines is to beat the cotton which tends to be carried upward. In addition, any air motion is upward. This air motion is quite important; it sets up a definite suction through the machines. During the beating about of the opening action, the cotton is repeatedly thrown against the inner casing, and the heavy particles, which are exposed, are thrown off, passed through the openings, and settled outside the beater chamber.
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| UNIVERSAL CLEANER CL-P Main operation during cleaning Opening of larger particles of cotton and the removal of large motes, pieces of trash, and other heavy foreign matter present in the cotton. |
Blending
Nowadays, blending or mixing of cottons is accomplished by the use of a multi-blender. These machines have 6 to 8 rooms, and the more rooms the machine has, the better the blending results. There are two openings in each room, one at the top and one at the bottom. Cottons are deposited into each room in a sequential order through the top opening and dropped onto a conveyor belt from the bottom opening. The conveyor belt carries tufts of cotton from different rooms towards a stripping roller which further beats cottons into fine and small particles. |
| MIXER (MX-I) Main operation during Blending Mixing and Blending of cotton for better result with low cost of manufacturing. |
Foreign Substance Detector
Spinning mill problems associated with foreign matter in cotton have increased during the past years. In developing countries with their low labor costs, it is not uncommon to employ up to 100 persons per shift for contaminant screening. However, in high labor cost regions, automated systems are the only sensible alternative. For example, magnets located after the automatic bale opener or cleaner would pick up any tramp iron particles which might be picked up with the cotton at the feeding bale. Newly developed foreign substance detectors are also recommended to be arranged in the blowing room for high quality bleached white or raw white yarn.
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| Foreign Substance Detector(SP-FPU) Main operation of Foreign Substance Detector
Removal of contamination such as plastic,Jute Particle, Paper from the cotton.
CARDING
Carding is the last major stages of opening and . It is also where separated fibers are converted into the rope-like sliver form.
The design of the card developed in the nineteenth century. According to GUNTER there was little basic change over the next century except for the introduction of ‘revolving flats’ that move slowly over the surface of a rotating cylinder. The word ‘revolving’ does not mean that the flats revolve about their own axes but merely that they move around a specified path. The teeth on the active elements have to be very fine because they have to be capable of handling single fibers. The order of magnitude of a typical dimension is 0.1inch. It also means that they are vulnerable to damage from foreign objects.
FUNCTIONS OF CARDING
CARDING ACTION
Two alternative arrangements of the carding elements exist; in one, moving flats cooperate with the cylinder and in the other, fixed plates or segments are used. In the first case, some 40 flats are linked together and move slowly over an arc of the rotating cylinder. The surface speed of the cylinder is usually in the range of 457 m/min. There is a small clearance between the teeth, the setting of which can be varied from 0.2 to 0.5 mm according to the fiber being processed. Thus the shear rate is very high and a tuft of fibers caught by one set of
teeth is wrenched apart by the opposing set. There is very little time for the fragments of the tuft to relax until the next division is applied to them. Consequently the fibers within the tuftlets retain some orientation in the direction of shear, i.e. in the direction of movement of the surface of the cylinder. This permits a carding action.
It is possible to replace the flats and their cleaning apparatus by a simple curved plate with fixed teeth when carding clean fibers of relatively even length. Some designs exist in which trash can be evacuated from between the segments by interposing small wedge shaped plates that deflect the flow of air. The distances between the tips of the teeth on the fixed tops and tips of the teeth on the cylinder have to be carefully adjusted. Also care has to be taken with trash evacuation systems to ensure that they do not choke. Such chokes might not be detected immediately but cause deterioration in quality that might not be diagnosed in the early stages. Worn teeth give trouble and it is customary to test the card output for nep on a regular basis to provide a control. When the nep levels exceed a level determined by experience, grinding or rewiring become necessary.Excessive wear would require regrinding to remove the metal between AA’ and BB’ before an adequately sharp edge could be attained. (Of course, the clearance would be restored to AB but the tips become wider.) The teeth are case hardened and consequently there is only a limited number of regrinds that can be carried out under normal conditions before rewiring becomes necessary. Case hardening means that the body metal has a thin skin of harder metal. For the extreme case portrayed, it would then be likely that the case hardening had been ground away, in which case there would be very rapid wear when the wire was put in to service again. Also it would be questionable whether a sufficient degree of fiber penetration could be achieved with the wide tooth tips. In regrinding, too heavy a cut with the in situ apparatus used to grind the tips of the wire causes burrs to form for a view as seen with a pocket microscope). This condition might give good nep performance at the start but the performance deteriorates rapidly thereafter. If problems persist, it might be time to investigate other designs of card wire. The fibers leaving the flats on the surface of the cylinder are sometimes exposed to another carding and/or cleaning process. Carding segments somewhat similar to, but larger than, the flats carry out the carding at this stage and further cleaning may be carried out by installing a knife edge with proper air pressure control and waste removal facilities. A cleaning edge is an effective way of removing pepper trash but care has to be taken to monitor the condition of the knife edge. Hard particles and abrasive material tend to nick and wear the vulnerable edge that then creates nep and causes operational problems.Merenyi reported the sensitivity of the plate-to-cylinder and flat-to-cylinder
settings. With a 0.008 inch flat setting the mass of flat strip removed increased by 150% as the plate setting was changed from 0.017 to 0.019 inch. The work was probably carried out with wire1 clothing but it still has some relevance.The reason can be imagined when it is realized that the ingoing nip of two large cylinders rotating in proximity creates a considerable pressure especially along the line A–A . Unless the pressure is controlled and contained, it tends to blow out in the direction of the gray arrows and carry dust and lint with it. There is low pressure under the cylinder/doffer nip and the flow of air from the high to the low pressure zone affects the fiber orientation in the fiber transfer zone. The air pressure gradient in this zone affects air leakage as well as the fiber transfer between the cylinder and doffer.
DRAFTING
Historically, the term ‘drawing’ was used in connection with the drawframe in staple spinning. ‘Drafting’ was used regarding roller drafting systems in roving and ring spinning. Upon the appearance of man-made fibers, the term ‘drawing’ was also used to describe the elongational process to improve the molecular orientation of the filaments. Custom still insists on the use of the historically founded words but in essence there is little fundamental difference between drafting and drawing. Linear density is defined as mass per unit length of a strand or along the flow path of a stream of fibers.
Purposes of Drafting
Drafting occurs when a stream of fibers passes through an acceleration zone5. The place where the acceleration occurs is called a ‘draft zone’ and it is necessary to control the fiber flowing through it. The solutions to the problem of fiber control are diverse and only a few examples can be given to illustrate the importance of mass flow control by passive devices.There are two major reasons for drafting or drawing, which are
There are cases that are not always regarded as drawing but which really are. For example, in extrusion, the linear density of the molten polymer approaching the spinneret is higher than the sum of the linear densities of the output filaments even before conventional drawing. The speed of the output material is faster than that of
the input. While an extruder is not regarded as a drawing machine, it always is.
Control of flowing material
Both polymer and staple drawing and drafting have instabilities in flow. Control is exercised by imposing restraints on the systems. With polymer in the solid state, control is exercised by hot pins or the like. Heat flow from the control surface permits control of the local visco-elastic constants of the polymer in such a way as to promote stability. In the case of staple processing, the variable frictional forces between the flowing fibers are a strong factor in producing the instability, which reduces their value in both yarn and fabric forms. These instabilities produce quasi-random errors in the product. The addition of an external retarding force to the flowing fiber reduces the instability.
Principle of drafting or drawing
Consider a sample of the input material before and after discontinuous drafting or drawing. If there were no losses in the process, the mass of the input sample would be the same as it is after drawing. Let be the packing density (not to be confused with linear density), a the cross-sectional area, l the sample length, iaili be the mass in the input sample, and oaolo be the mass after drafting.
Drawing in staple fiber processing
In staple spinning, the material flows through the drafting or drawing zones of the equipment. (The term ‘drawing’ is often used to describe the particular overall process but it is common to refer to the components that carry it out with the adjective ‘drafting’. Thus we speak of drafting rolls and draft in a drawframe which seems odd, but that is the common usage.) Fibers are accelerated as they pass through each zone. Also fibers can, and do,migrate with respect to one another along the direction of flow. Conventional theory
has been mainly restricted to roller drafting, in which there are fiber acceleration zones within the spaces between two consecutive sets of rollers. (A similar idea applies to filament drawing but godets are used rather than rollers. Godets are cylinders about which a yarn is wrapped to grip the yarn for the purpose of elongating it.) However, fundamentals merely require that the exit material moves at a greater velocity
than the entry material. The theory in Appendix 8 seeks to include the case where fibers are drafted by toothed rolls.
Error During Drafting
Periodic errors
Roller or godet defects such as those previously described translate into periodic errors in yarn, roving, sliver or tow, which are sharply defined. Not only does the linear density of the material vary in consequence but so also does the structure of the material strand.
Random errors
Textile strands also contain random errors with a very wide spectrum of errors.Staple fiber drafting,Fluted,bottom rolls,Reaction,Single sliver output,Reaction,Weighting Weighting,Multiple,sliver input,Rubber-covered top rolls,Rubber-covered top rolls
Cumulative effects of drafting
Where there is a number of drafting stages, the results are cumulative and the range of error wavelengths can be very large. Yarns show not only an extremely large range of error but these errors translate into faults in the fabric. The end result of these irregularities is that the fabrics made from the yarns show undesirable patterning known as moiré or barré, which reduces the
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