NEW GRATE CONSTRUCTION FOR LINTER MACHINES

ABSTRACT

This article presents the results of the selection of a new technology and new materials for the production of grates used in the technological system to increase the efficiency of the grain lintering process. The main disadvantages of the current cast iron grates of the СЧ15–32 brand were identified, such factors as a high coefficient of friction, susceptibility to corrosion, low wear resistance, and a decrease in product quality. During the research, several materials were compared, including steels of the В2Ф, 08X18H10, and 32НК–ВИ brands, and their coefficient of friction and hardness were studied. According to the experimental results, stainless steel of the 32НК–ВИ brand was identified as the most optimal material for the manufacture of grates. In addition, a technological process for the manufacture of a grate of a new design from stainless steel of the 32НК–ВИ brand on a modern laser machine is proposed. Due to its corrosion resistance and low coefficient of friction, its use in the lintering process increases fiber separation efficiency, reduces grain clogging, and improves product quality.

АННОТАЦИЯ

В данной статье представлены результаты выбора нового материала и новой с изготовления колосников, используемых в технологической системе линтерования хлопковых семян с целью повышения эффективности процесса. Выявлены основные недостатки существующих чугунных колосников марки СЧ15–32, такие как высокий коэффициент трения, подверженность ржавлению, низкая износостойкость и низкое качество получаемой продукции. В ходе исследований проведено сравнение нескольких материалов, в том числе марок стали В2Ф, 08Х18Н10 и 32НК–ВИ, изучены их коэффициент трения и твердость. По результатам экспериментов наиболее оптимальным материалом для изготовления колосников была определена нержавеющая сталь марки 32НК–ВИ. Кроме того, предложен технологический процесс изготовления колосника новой конструкции из нержавеющей стали марки 32НК–ВИ на современном лазерном станке. Благодаря коррозионной стойкости и низкому коэффициенту трения данного материала, его использование в процессе волокнообразования повышает эффективность отделения волокон, снижает повреждение семян и улучшает качество продукции.

Keywords: material, technology, cotton seeds, efficiency, cast iron, friction coefficient, hardness, stainless steel, laser machine, product quality.

Ключевые слова: материал, технология, хлопковые семена эффективность чугун, коэффициент трения, твердость, нержавеющая сталь, лазерный станк, качество продукции.

Introduction. Large-scale scientific research is being conducted in the world to improve the process, techniques and technology of separating cotton lint from seeds. In this direction, in particular, scientific foundations are being developed to increase the efficiency of the cotton linting process, and attention is being paid to improving product quality and reducing costs by accelerating the widespread introduction of scientific, as well as modern techniques and technologies into production. In this regard, the creation of technologies that allow maintaining the initial quality indicators of lint and seeds, reducing energy consumption, and controlling product quality, as well as perfect equipment that consumes less material and energy, has risen to the level of urgent issues in the industry.

In the Republic of Uzbekistan, special attention is paid to increasing the production of high-value-added finished products based on deep processing of cotton raw materials, improving the structure of the country's cotton ginning industry, reducing the cost of cotton products and improving their quality indicators based on technical and technological restructuring. The New Uzbekistan Development Strategy for 2022-2026 sets out tasks, including "...to ensure the rapid development of the national economy and high growth rates and to double the production volume of textile industry products". In fulfilling these tasks, it is important to increase the efficiency of the linting process by developing a resource-saving design of working bodies for the lint separator machine based on theoretical and practical analysis of the process of separating cotton lint from seeds , including increasing the efficiency of the linting process and reducing energy consumption by coordinating the speed of raw materials[1, 2].

Main part. The aim of the research is to improve the efficiency of the lint separation process by developing a new grate design for the linter machine.

Current on the day seed linting technology done increase 5LP linter equipment is used for. In this equipment, the linting process is carried out as a result of the impact of a saw cylinder on a seed roller in the working chamber. Under the influence of a rotating mixer and a saw cylinder in the working chamber, the seed in the chamber forms a densely rotating sew roller (Figure 1). The saw teeth entering the sew roller scrape the fluff from the seed surface and carry it behind the grates. After the fluff is scraped from the seed surface, this seed loses contact with the seed roller, falls onto the grate surface between the saws and moves down to the seed grate zone to exit the working chamber. If there are no obstacles to the movement of the seed, this seed exits the chamber in the grate zone [3].

Figure 1. 5LP model linter equipment worker Scheme of the linting process in the seed chamber

1- working chamber, 2- cleaner, 3- seed grate, 4- grate, 5- saw cylinder, 6- seed roller .

Due to the low efficiency of the lingter in terms of seed and lint, in accordance with the harmonized technology for primary cotton processing PDI 70-2017, two rows of 6 linters in each row, for a total of dozen 5LP linters, are installed in the seed linter shops of cotton ginning enterprises.

Initial studies conducted to improve the lintering process revealed that the friction coefficient of the working surface of the combustor and the working chamber has a strong influence on the process parameters.

Also, in the past, cast iron was widely used and any shape of parts could be cast from it. In addition, cast iron does not produce sparks when it comes into contact with saw teeth. Considering these properties, the grates of fiber separator machines were cast from cast iron [4].

Method. The friction coefficient of the working surface depends on the material of the working surface and the degree and quality of its processing. Also, the current technology for preparing a linter grate is complex and time-consuming. Based on these considerations, the authors developed a technology for preparing a linter grate by cutting it from a material with high tribological properties, that is, a low friction coefficient, sufficient hardness, and no sparks when exposed to saw teeth [5].

Results and their analysis. The roughness of the working surface of the samples was studied in laboratory conditions. Experimental work was carried out on the Time 3200 device. This device is capable of determining the area of the material up to 10 mm in length. Here, it is necessary to subject the surfaces of the materials to the same processing. Therefore, the processing process was carried out with the same grinding operation for each material. The value of the surface roughness is measured using a specially installed sensor.

Figure 2. Difference in friction coefficients of materials in the form of a histogram

The process of studying the friction coefficient of materials was carried out on a T25 model device designed to determine the friction coefficient, which is available in the laboratory department of Namangan State Technical University. For the experiment of determining the friction coefficient, the current cast iron material of the СЧ15-32 grade, steel of the B2Ф grade, stainless steel materials of the 08Х18Н10 and 32ХК-ВИ grades were taken. For the experiment, Andijan 35 selleksion, and cotton of the II industrial grade were taken.

Combining the above results, it can be concluded that it is advisable to obtain and use a liter cylinder from stainless steel grade 32HК-ВИ as the material with the lowest friction coefficient [6].

In studying the hardness of the samples, Rockwell and Brinell presses were used, since this press can determine the hardness of even very hard materials. The research showed that the hardness of the material selected for the linter grate at “Namanganmash” LLC was tested in the laboratory. The hardness of the samples obtained is given in Table 1.

Table 1.

Hardness of the samples obtained

New linter grate manufacturing technology. It is worth mentioning separately that in the manufacturing of cotton ginning machine parts, including gin and linter machine parts, gray cast iron parts are being replaced with steel parts. In the manufacturing of such parts, a laser machine is being effectively used.

Figure 3. Laser cutting process of selected 6 mm stainless steel material

The error of laser machines is 0.1 mm. Any metal materials can be cut to the exact size if a design drawing is loaded into the machine's memory. The above machine shows an overview of the cutting process of a new linter grate. (Figure 3).

Table 2.

Technological process of preparing 1 piece of offered linter grate

A)                                                                  B)                 

Figure 4. A) side view, B) top view of the newly developed linter grate

The proposed new linter grate consists of a single piece of material, the material of which is 32НК-ВИ. The sequence of technological processes for the preparation of a structure made of stainless steel of the grade 32НК-ВИ selected for the linter grate is presented (see Table 2).

The newly developed linter grate construction can be seen in Figures 4 and 5:

Figure 5. Experimental copy of a new linter grate made of stainless steel

The corrosion resistance of linter grates was studied. A new linter grate structure and existing cast iron grates were taken for corrosion testing. The “Grate corrosion testing device” was used to test corrosion in the laboratory conditions of the Andijan Machine Building Institute. Based on the test results, a new linter grate for It was argued that the use of 32НК-ВИ grade stainless steel material has lower corrosion resistance than the current one [7].

The new linter grate was tested for strength and the allowable stress was determined in Solidworks.

The coefficient of friction and the amount of wear of the material correspond to 0.01 mm for the above material 32НК-ВИ stainless steel. It can be seen that the 32НК-ВИ material for the grate is correctly selected.

Conclusion

1. As a result of theoretical analyses, it was found that the speed of the seed falling from the working chamber depends on the coefficient of friction between the surface of the grate and the seed, and at small coefficients it leads to an increase in the seed speed.
2. The efficiency of the linting process depends on the speed at which the cleaned seed exits the working chamber, and it is theoretically necessary to reduce the friction coefficient between the linter grate material and the seed to accelerate the seed exit and increase efficiency.
3. Experimental studies have shown that the friction coefficient for cast iron of the СЧ15-32 grade is µ=0.75 and 0.78, for steel of the В2Ф grade is µ=0.56 and 0.62, for 08Х18Н10 grade is µ=0.51-0.48 , and for stainless steel of the 32НК-ВИ grade is µ=0.46 and 0.48, and it is recommended to select and use stainless steel of the 32НК-ВИ grade as the material with the lowest friction coefficient. has been found to be appropriate.
4. As a result of the introduction of a new, tribologically improved, cutting-made grate at the cotton ginning enterprise, the mass fraction of defects and impurities in the cotton lint was reduced by 0.3% (absolute), the mechanical damage of the seed by 0.7%, the energy consumption of the linter machine (per 1 linter) by 4 kW/h, and the productivity was increased by 300 kg/h.

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