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21
Mukhtarov Jurabek Reyimberganovich,
researcher,
Tashkent Institute of Textile and Light Industry
Kulmetov Mirpolat, Professor,
Tashkent Institute of Textile and Light Industry E-mail: [email protected]
INFLUENCE POSITION OF FIBERS ON THE QUALITY OF PRODUCTION IN THE PROCESSES OF YARN PRODUCTION
Abstract: In this paper, the conditional density of cotton fiber bundle quality indicators, tapes and threads at the production stages of the yarn have studied. Research work was carried out at Beruny cotton cleaning plant and sealed fibers under different working pressure of fiber, threads of density 29.4 tex were spun in BD-320 pneumatic spinning machine of the Truetzschler brand. The physical and mechanical properties of the threads obtained as a result of the experiment were determined in testing laboratory "CentexUz".
Keywords: conditional density of pressing, processes, linear density, tape, working pressure force, yarn production.
The linear density of the production of textile industry, cotton fibers in Republic and Europe standards has a dimension in tex or millitex units, which depend on the length of the fiber type. According to modern standards, long-fiber cotton is divided into I-III types, and mediumfiber cotton into IV-VII types, that is, the linear density of the fiber changes in order of increasing type and the length, on the contrary decreases. If density or length of the fiber exceeds the established limits of norms, it goes to the type below as a result reduces the precocious sponge ability of yarn and low-quality products are produced.
Determination of a linear density of cotton fiber is a rather complicated procedure. In this connection, in America, the indicator of micronaire is introduced into the system of certification of cotton fiber, it is determined by the volume of the pribed air through a group of parallel fibers. The air resistance is proportional to the longitudinal section of the fiber. The fiber color according to the American standard is characterized by a degree of Rd (%) yellowness. One of the highest requirements is the color of cotton fiber has always been considered. Therefore, the reception of cotton fiber is carried out only in the day time, the laboratory technicians determine the fiber color by subj ective, classroom way and by comparison with special samples.
As a result of increasing the specific density of cotton fiber in the pressing process, the specific tensile load and the shaving length has been decreased which causes an increase in the number of short fibers and mechanical damage of the fibers.
In this regard, the physical and mechanical properties of the products were determined in the HVI 900 SA system, which were degenerated in the processes ofproduc-ing yarn from compacted fibers, at the enterprise of JSC "Beruni pakhta tozalash" from the baled I-variant 330 kg/m3, sealed under different operating pressures, The II variant is 375 kg/m3, the III variant is 425 kg/m3, the IV variant is 470 kg/m3and the V variant is 550 kg/m3.
The results of the research work are given in Table-1.
From the analysis of obtained results of scientific research it is evident that with an increase of working pressure of the pressed cotton fiber that is the compres-sional density of compression, the relative breaking load decreases the upper average length, elongation at break, on the contrary the index of short fibers increases.
Recently as a result ofspecial attention to small business and private entrepreneurship, a number ofprivate enterprises has been increasing. These enterprises for their development and for their products to occupy a worthy place in the world market economy must manufacture their products in
accordance with the established norms. To produce yarn ac- is necessary to control the quality ofsemi-finished products cording to the requirements, in yarn production processes it during the technological process.
Tablel.- Impact of the specific density pressing on the change of quality indicators of semi-finished product by the processes of yarn production
Spinning products Mic Micro-neur Str Comparative relative load, kg / text Len Upper middle length dm Unf The index of uniformity along the length, % SFI Short fiber index Elg Elongation at rupture % Cnt The amount of impurities Rd Reflection coefficient + b Degree of yellowness %
I-variant
Fiber 4.4 27.9 1.04 82.6 3.9 6.3 17 77.8 8.4
Ribbon 4.4 27.2 1.08 83.1 5.8 5.7 13 78.5 8.3
II-variant
Fiber 4.4 27.0 1.05 83.3 4.4 6.5 20 78.5 8.8
Ribbon 4.4 26.3 1.12 82.4 6.5 6.0 15 77.4 9.0
Ill-variant
Fiber 4.4 26.5 1.03 83.0 4.7 6.4 19 78.9 8.6
Ribbon 4.4 26.0 1.06 82.7 6.4 5.5 16 79.0 8.8
IV-variant
Fiber 4.4 24.7 1.06 83.5 4.7 6.3 18 75.4 9.1
Ribbon 4.4 23.5 1.03 83.5 6.9 5.1 17 76.2 9.0
V-variant
Fiber 4.4 24.4 1.02 83.6 5.2 6.4 22 75.0 9.4
Ribbon 4.3 22.8 1.10 83.9 7.9 5.2 19 76.5 9.6
In spinning enterprises cotton bales are subjected to trephination by means ofautomatic tearing machines and transferred to the next process. In the process of shaking the heads of the bodies of trepation for cotton fibers are repeatedly strong mechanical effects of quality. Product indicators will improve if produced under the condition that the working pressure force is reduced while pressing the fiber and the spinning processes are reduced.
When spinning a high degree of loosening of fibrous products, high-quality yarn for the production of pure and loosened yarn is of great importance. One of the most difficult problems in spinning process of yarns is the task of leveling products by stretching. As a result of pulling the fiber moves in the form of sliding relative to each other and the spreading of their front and rear ends is ensured, which makes it possible to produce an even,
strong yarn with a high degree of straightening and leveling the fibers relative to each other [2].
The greater the value of the flow, the better the fiber ends get straighten. In the carding belt the straightness of the fiber is 55%, in the tape from the tape-making machines the straightening is 71-75%, in the roving is 78-80%. The degree of straightening of fibers in the composition of products is influenced by the correct organization of spinning technology processes.
Joint venture "Berunium-teks" of cotton bales I-variant - 330 kg/m3, II-variant - 375 kg/m3, III-vari-ant - 425 kg/m3, IV variant - 470 kg/m3, and also V-variant - 550 kg/m3 in a pneumatic spinning machine of the brand BD-320 from the company "Truetzschler" was obtained yarns with a linear density of 29.4 tex. In order to determine the influence of the state of the
fibers on the quality of yarn in the processes of its pro- obtained from cotton fiber with bales of various density
duction samples were taken. of pressing studied. The results of the scientific study
In the processes of yarn production, the uneven- are shown in the (table 2). ness of carding tape and tape from tape-fed machines
Table 2.- Effect of the density pressing on the index of the unevenness of tape in the processes of yarn production
№ Technological transition Quadratic unevenness in linear density,%
I-variant
1. Carding process 3.71
2. Belt Process 3.90
II-variant
1. Carding process 3.83
2. Belt Process 3.95
Ill-variant
1. Carding process 4.70
2. Belt Process 4.01
IV-variant
1. Carding process 4.81
2. Belt Process 4.12
V-variant
1. Carding process 6.15
2. Belt Process 5.12
From the analysis of obtained results it is seen that with increasing density of pressing of cotton fiber the quadratic non-uniformity in linear density also increases.
In conclusion it was found that with increasing density of pressing of cotton fiber, the quadratic non-uniformity of the tape along the linear density after the combing process increased from 3.71% to 6.15%, after the belt process from 3.90% to 5.12%.
In the process of spinning yarn the thickness of the fibers is of great importance. The properties of the resulting yarn depend on the thickness of the fiber. Fine fibers are obtained from thin fibers with a uniform, stronger yarn. Thin and light fabrics, knitted fabrics are produced from fine yarn. The thinner the fiber the more fibers in the cross section of the yarn of different thicknesses.
At the same time the contact area of the fibers increases with each other and the frictional force increases, as a result, the strength of the filaments becomes higher. Since the relative strength ofyarn from thick fibers is low for a thin yarn this indicator is quite weighty.
To obtain normative and qualitative yarn proofers there must be a certain amount offibers in the yarn cross section.
To obtain yarns with a minimum linear density the linear density of the fiber is crucial.
Hence, in the cross-section of the yarn section of minimum thickness, a number of minimal fibers can be variable. For fibers which thickness is too thin there are also negative sides. For example, during the spinning such fibers are more often entangled nodules are formed as a result of this the appearance and quality parameters of the yarn get worsen.
The most important factor in thickness of the unevenness is yarn. As a result of unevenness twists have been appeared and their appearance is disturbed. With the increase ofyarn unevenness the use of the strength of fibers from yarn from tangled yarns is reduced as a result the mechanical properties of yarn deteriorate the discontinuity in the process of knitting and weaving has increased.
In yarn production the mechanical properties of cotton fibers are important in spinning process that is resistance to abrasion, compression, bending and convergence of fibers to each other.
Along with this in the production of high-quality yarn in spinning enterprises, the length, strength,
breaking load and linear density of the fibers are of great importance. The higher the quality of the fiber it is possible to produce yarn that meets the requirements and is in great demand. And for this it is necessary to choose the right raw materials and in cotton ginning enterprises store raw cotton in warehouses to create optimal conditions for drying, cleaning, separating fiber from seeds and cleaning the fiber.
Research work was carried out to produce a high-quality yarn in the market economy. For this purpose from fibers with a bale density: I-variant - 330 kg/m3, II-variant - 375 kg/m3, Ill-variant - 425 kg/m3, IV variant - 470 kg/m3, and V- option - 550 kg/m3, a 29,4 tex yarn was obtained and their physical and mechanical properties were studied in the "CentexUz" laboratory.
The results ofscientific research are given in (Table-3).
Table 3.- Effect density of pressing on physical and mechanicalproperties of yarn
The density of pressing, kg/m3 Linear density of yarn, tex Square unbalance by linear density,% Number of twists 1 meter Quadratic unevenness in the number of torsions, in%
330 24.9 2.4 566 4.6
375 24.5 3.2 642 6.7
425 24.9 3.6 574 6.8
470 24.8 4.8 588 8.4
550 24.9 6.7 622 10.4
In conclusion it was found that with an increase in the density of pressing of cotton fibers from 330 kg/m3 to 550 kg/m3 the quadratic unevenness of the tape along the linear density increases from 2.4% to 6.7%, quadratic unevenness by the number of twists from 4.6% to 10.4%.
Hence it was determined that with the increasing pressure force in the process of pressing cotton fiber, the density of pressing has increased resulting in increased quadratic unevenness in linear density and quadratic un-evenness of the resulting yarn.
The significance of the difference in average indicators of the quality of the results study was estimated by the Student's test with a confidence level of PD = 0.95.
The significance of the homogeneity of the variances of the results was btained on the basis of Fisher's criteria. For this an estimate of one and the same normal of the variance is. The hypothesis is checked against three competitive hypotheses; Taking into account the correspondence of the random variables U1 and U2 to the normal distribution law two variances were compared and evaluated by the criterion F (Fisher) [3]. S2
A special case: F = —p a large dispersion of both in
the figure.
Fisher distribution
S2
F =
SM sUy}
-Yiv. -
m,
- i^V
y2i - y2 )
-Yiy. -
m
- i^v
y2i - y2 )
Where: FT {PD = 1 - a; f = m1 -1; f2 = m2 -1} was compared with the table value.
Fr < FT if, of ^ o- was assessed by bilateral critical boundaries.
Conclusion
In conclusion we can say that: - that with the increasing pressure pressing the cotton fiber, i. e., a conventional density of pressing, relative load of the upper average length, the elongation at breakage has been reduced, and the index of short fibers on the contrary increased.
- that with the increasing density of pressing of cotton fiber, the quadratic irregularity of the tape along the linear density after the carding process increased from 3.71% to 6.15%, after tape process from 3.90% to 5.12%;
- with an increase in the density of pressing cotton fibers from 330 kg/m3 to 550 kg/m3, the quadratic irregularity of the tape along the linear density has increased from 2.4% to 6.7%, quadratic irregularity in the number of twists from 4.6% to 10.4%. The significance of the difference in the average quality indicators was estimated by the Student and Fisher criteria with the probability of reliability PD = 0.95;
- Due to the fact that when the pressure force is increased in the process of pressing cotton fiber, the physical and mechanical properties of the resulting yarn has been deteriorating the optimal options for the density of pressing 470 kg/m3 were recommended for production.
i
References:
1. Sengoz N. G., Arslan P. "Application and evaluation of some quality control methods to unevenness measurements of carding slivers" 12th International Conference - Standardization, Prototypes and Quality: A Means of Balkan Countries' Collaboration - 2015.- P. 443-451.
2. Ibragimov Kh. H., Jumaniyazov K. J., Matismailov S. L. and others. "Special spinning technology". Textbook-Tashkent. HAM-3ne,- 2006.
3. Sevostyanov A. G. "Methods and Means for Investigating the Mechanical and Technological Processes of the Textile Industry - A Textbook for Textile Industry Institutes". Textbook,- M. MSTU them Kosygin,- 2007.-P. 72-75.
