INVESTIGATION OF MECHANICAL DAMAGE OF COTTON FIBER IN THE PROCESS OF PRESSING AND BALING

ABSTRACT

Boston Cluster LLC conducted research to study the mechanical damage of 5-I, 5-II sorting fibers under the influence of repeated shocks during the spinning process. I, II-class high, good and middle class fibers of "Sultan" selection were used for experiments. The studies were organized in two options: in the 1st variant samples were prepared from the crushed fibers and in the 2nd variant from the crushed fibers, and the mechanical damage of the fibers under the influence of repeated shocks was studied. Prior to testing, the samples were stored in a standard environment in accordance with the requirements of GOST 10681-75. In order to study the effect of moisture content and working bodies on the mechanical damage of the fibers, the test laboratory "SentexUz" prepared the final fibers in the form of both variants. In order to study the different changes in the physical and mechanical properties of fibers, experiments were conducted on the basis of academician M.A. Khadzhinova's method.

АННОТАЦИЯ

Проведены исследования в производственных условия ООО «Bo’ston Cluster» с целью изучения механических повреждений волокон сортировки 5-I, 5-II при повторных ударных воздействий в технологических процессах прядения. Для опытов отобраны волокна селекционного сорта Султан» I, II сортов высшего, хорошего и среднего классов Исследования проводились в двух вариантах: в 1-м варианте использовались спрессованные в кипы волокна, а во 2-м – разрыхленные волокна и изучили механическое повреждение волокон при воздействии многократных ударов. До испытаний образцы хранились в стандартных условиях в соответствии с требованиями ГОСТ 10681-75. С целью изучения влияния воздействий рабочих органов и влажности на механическую повреждаемость волокон в испытательной лаборатории «SentexUz» из каждого образца были подготовлены конечные образцы ленты. Проведены опыты с использованием методики акад. М.А.Хаджиновой для изучения изменения физико-механических свойств волокон.

Keywords. Cotton fiber, fiber properties, mechanical damage of fibers, academician M.A. Khadjinova method, Uster HVI 1000 system, Uster Statictic 2018 indicators.

Ключевые слова: Хлопковое волокно, свойства волокна, механическое повреждение волокна, акад. метод М.А. Хаджинова, система Uster HVI 1000, индикаторы Uster Statictic 2018.

Introduction. The main goal of the study was to further improve the activities of cotton and textile clusters, the widespread introduction of market principles to ensure the interests of producers and processors. From 2022, the main task for cotton and textile clusters is to have an annual volume of raw cotton in cotton and textile clusters, including more than 30,000 tons, and to have at least 50% of the raw material grown on-site processing capacity (at least spun yarn) [ 1].

In order to implement these tasks, in particular, large-scale work is being carried out in the country to improve product quality and increase production efficiency at ginning and spinning enterprises.

In the yarn production system, a decrease in the length of the cotton fiber results in an increase in the amount of short fibers, waste, and a decrease in the tensile strength of the fibers. That is, in a spinning system, as the length of the cotton fiber decreases with each 1 mm of length, the elongation at break of the yarn decreases, and the longer the cotton fiber, the smoother, thinner, more durable yarn is obtained. In addition, long-term storage of high-density cotton seed during the initial processing of cotton, as well as fiber damage, fiber structure damage, and a decrease in length due to various biological and various technological influences have been identified in scientific studies [2,3].

Theoretical part. In the technological systems of spinning mills, cotton bales are first shredded in auto-feeders and then transferred to the next stage for cleaning and mixing. Strong repetitive mechanical effects on the fibers in automatic spinning mills with spinning body headsets lead to an increase in the proportion of short fibers, a decrease in the quality of the combing fiber, and a decrease in the amount of yarn. It has been scientifically proven that the quality of spun yarn improves as a result of optimizing the conditional density of the yarn by reducing the working pressure force in spinning the cotton fiber [4,5].

In the technological system of yarn production, the reduction of damage to the fiber length is of great importance in spinning small, linear density, smooth and mature yarn. The fibers of the mixture undergoing technological processes are damaged by repeated mechanical shocks, their properties decrease, short fibers increase and long fibers decrease [6].

The aim was to study the factors affecting the physical and mechanical properties of the fiber in the production process, the effect of repeated mechanical forces on changes in the physical and mechanical properties of the fiber in the initial processing of cotton fiber during pressing and spinning [7].

Experimental section. In this study, in order to comparatively determine the mechanical damage of spun fibers and shredded fibers under the influence of working bodies, experiments were conducted on the basis of academician M.A. Khadzhinova's method [8].

In the preparation of the sample were used I, II-class high, good and middle class cotton fibers of the "Sultan" selection, included in the 5-I, 5-II selection. The studies were organized in two options: in the 1st variant the samples of the crushed fibers and in the 2nd variant the samples of the crushed fibers were used.

In the analysis of the samples, attention was paid to the change in fiber properties in each process. The performance of cotton fiber was studied in the laboratory of the joint venture "Wakefield Inspection Services (Tashkent) Ltd" under Tashkent Institute of Textile and Light Industry in the system Uster® HVI 1000 and summarized in Table 1 [9].

 Table 1.

Indicators of cotton fibers

From the analysis of the test results given in Table 1, the physical and mechanical properties of the spun fiber of variant 1 in relation to the fiber that underwent the spinning process of variant 2: spinning ability index (SCI) increased by 4.47% and was considered important in spinning. Decreased by 1.83%, while the short fiber index (SFI) increased by 16.7% [10].

Samples of both variants of the yarn designed for the production of yarn at “Boston Cluster” LLC were prepared in accordance with the requirements in a standard environment and prepared for experiments. In order to study the effect of moisture on the mechanical damage of cotton fiber and the working bodies in the technological process, samples of both options were taken in the test laboratory "SentexUz" and the final cocoon was prepared on a cocoon making tool (V.N. Zhukov) [11].

Drugs were prepared from the final fibers and tested in the testing laboratory of the Center for Advanced Technologies under the Ministry of Innovation Development of the Republic of Uzbekistan, the existing electron microscope "SEM-EVO MA 10" (Zeiss, Germany). It was studied using the Khodzhinova method.

Studies have shown that as the density of spun cotton fiber increases, the amount of mechanical damage to the fiber also increases, mechanical damage to the fiber is analyzed depending on the degree of maturity, and it is more common in unripe fibers. As a result of mechanical damage, the angle of deflection of the fiber structure increases, resulting in a violation of the orientation of molecules in the fiber [12].

The degree of damage to cotton fiber can be analyzed by type and degree of damage by class and group, such as maturity, determination of the cut width of the damaged area, determination of the width of the fiber damage and compression cut.

When the cotton fiber is mechanically damaged, a very thin bar is observed, as well as splitting into rough cracks (pic. 1).

Figure 1. Mechanically damaged fibers

The greater the mechanical damage to the fiber, the higher the deflection angle of the structure.

As a result of mechanical damage, the angle of deflection of the fiber structure increases, resulting in a violation of the orientation of molecules in the fiber.

Microcircuits were prepared and analyzed on the fiber cross-sectional surface, mathematically sorted, and the degree of maturation of the damaged fibers was determined according to the cross-sectional surface summarized by V.S. Fyodorov's method, it was recommended to find the following.

F_р  =                                                                        (1)

Professor A.N. Colovyov recommended to determine the coefficient of fiber beating in the initial and processing of cotton as follows [13].

  ;                                                                           (2)

where the amount of fiber shorter than K-15 mm,%

L_m -is the modal mass length of the fiber, mm.

It is possible to determine the degree of damage of cotton fiber to maturity, to determine the cut width of the damaged area, to determine the width of the damaged and compressed cut of the fiber, to analyze the type and degree of damage by their class and group.

The effect of moisture content on the mechanical damage of cotton fibers in the toy work was determined by the maturity of the cotton fiber, and the results are given in Table 2 below.

 Table 2.

The effect of moisture on the mechanical damage of cotton fiber

The results show that the total mechanical damage to the fiber decreased by 15 when the moisture content of cotton was 8.0%, and by 9 when the moisture content was 9.5% (Figure 2).

Figure 2. Damage to cotton fiber at different humidity

It can be noted that the amount of mechanical damage increases as the moisture content of cotton fiber decreases. In addition, when analyzing the mechanical damage of the fibers according to the degree of maturity, it was observed that they were more in the unripe fibers.

It can be seen that as a result of the increase in tension in the fiber bundles under the influence of repeated impact forces in the technological processes of cotton fiber, the formation of bumps and cracks on the fiber surface, the fiber properties changed negatively. In particular, from the geometric properties of the fiber, it was found that the short fibers increase in the sequence of processes, while the index of uniformity along the length of the fiber decreases.

Conclusion. Based on the results of the study conducted to study the changes in the physical and mechanical properties of saturated fibers and fibers that have undergone the process of leaching, the following conclusions and recommendations were made:

1. With the increase of mechanical damage of the fiber, the length of the staple mass of the fiber, the tensile strength decreases, on the contrary, the amount of short fibers increases.

2. In spinning, pressing and baling processes of spun cotton in the spinning system, due to the length of the technological lines, the natural properties of the fiber deteriorate under the influence of repeated strokes, leading to a decrease in the ability to spin quality yarn.

Reference:

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