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2KHCKA XAEAMAP PHYSICО-MECHАNICАL PRОPERTIES ОF PОTАTО CRОP
B.A.Khatamov
NamECI, associate professor, E-mail: [email protected]
G.K.Payziev NamECI, associate professor
S.T.Kodirov NamECI, associate professor
K.Ergasheva NamECI, associate professor
Аbstrаct. The article presents the results of experimental research conducted to study the physical and mechanical properties of potato crops, such as lodging and direction of haulms stalks on the field, which is of great importance for the correct and justified design and calculation of working bodies and machines for the mechanization of their cultivation and harvesting, including potatoes. Our experiments show that when pulling bushes with green and somewhat wilted haulms, 60-70% of the tubers are removed from the dug bed along with the stems. This condition of the haulms during the potato harvesting period in the Republic of Uzbekistan, the no- black soil zone of the Russian Federation and other countries of the Commonwealth of Independent States is typical. The given data give us grounds for the correct choice of the location of the haulm removal working body in the technological scheme of a potato harvester, especially one that uses a method of separation by size (screens with longitudinal bars, conveyors with transverse bars with large gaps between them).
1. Intrоductiоn
The study of the physical and mechanical properties of agricultural crops is of great importance for the correct and justified design and calculation of working bodies and machines for the mechanization of their cultivation and harvesting, including potatoes.
Since this article discusses the issue of separating haulms from tubers in potato harvesters, the basic physical and mechanical properties given relate only to haulms stems and potato tubers, such as friction coefficient, strength of stems and stolons, dimensional characteristics and others. All these properties of the potato plant are not constant. They may vary depending on the potato variety and the soil and climatic conditions of its growth.
When pulling a potato bush, especially from a previously dug bed and when the haulms are green, a significant number of tubers, firmly held on the stolons, are removed along with the stems. In the works of many researchers, the number of extracted tubers is about 50% or more [1-9].
Research conducted by them shows that the number of tubers removed from the haulms depends on the degree of potato ripening. When pulling bushes with dried haulms, a small amount of tubers is extracted, only about 6% by weight of the bush harvest. With green bushes, 50 percent or more of the tubers are extracted.
2. Mаteriаls аnd methоds
Experimental studies were carried out at the Nanai farm in the Yangikurgan district of the Namangan region on mid-season potato varieties. Before conducting the experiments, the classification of the agricultural background was studied and the size and mass indicators of potato haulms and tubers, as well as its yield, were determined.
The research was carried out on the basis of generally accepted methods of theoretical
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mechanics, probability theory, strength of materials and mathematical statistics. Experimental studies were carried out on the basis of multifactorial experimental plans. The analysis of the obtained data was carried out using the programs "Statistica 10", "Microsoft Excel" and "Math CAD 15". Laboratory and field studies were carried out according to Gov. St 20915-2011 "Agricultural machines. On the basis of the Methods for determining test conditions" requirements for harvesting potatoes and the operation of potato harvesting equipment, the physical and mechanical properties of the components of the tuber heap, and an analysis of the designs of rod elevators was carried out Gov. St 28713-2018 "Potato harvesting machines" Test methods [6, 9-13].
3. Results and discussion
Our experiments show, table 1 that when pulling bushes with green and somewhat wilted haulms, 60-70% of the tubers are removed from the dug bed along with the stems. This condition of the haulms during the potato harvesting period in the Republic of Uzbekistan, the no - black soil zone of the Russian Federation and other countries of the Commonwealth of Independent States is typical.
Potato tubers, as shown by the practice of mechanized potato harvesting, as well as a number of studies carried out, when passing through the separating organ, are not completely torn off from the haulms; after passage, up to 20-30% of the tubers remain, for which additional devices in the haulm removal working bodies are required to be torn off [1].
Therefore, studying the strength of stolons, as well as haulms stems, is of great interest when justifying the parameters of the haulms removal working body. As can be seen from table 2, the breaking forces of the stolon itself, as well as the force of separation of the stolon from the roots, are greater than the force of separation of the tuber from the stolon.
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Tаble 1
Variety Humidity, % Weight of tubers (kg) extracted from the soil Weight of tubers (kg) not removed from the soil Percent tubers, extracted from the soil
haulms soil
Before digging up the formation
Lorch 88,5 18,5 0,737 0,660 52,7
Santa 70,3 16,1 0,480 1,073 30,9
After digging up the formation
Lorch 83,7 15,4 0,687 0,270 71,2
Santa 52,4 17,2 0,580 0,340 63,0
Tаble 2
Strength оf stоlоns in relation tо different pаrts оf the plant
Variety Date Force, N
tuber separation from the stolon stolon separation from the roots stolon rupture
avg max min avg max min avg max min
Lorch 22.10.93 10,3 18,0 0,8 11,7 23,0 2,0 14,6 33,5 6,0
Santa 22.10.93 11,1 23,2 1,0 12,2 30,0 4,0 20,8 34,0 6,0
Since when removing haulms from a combine it is necessary to separate the tubers from the stolons, we are more interested in these data. The minimum value of the force to separate tubers from the stolon was 0.8-1.0 N, and the maximum was 18.0-23.2 N.
Table 3 presents the breaking forces of the haulms stem by average diameter. However, this is not enough to justify the parameters of the haulmping working body. More complete data is needed to clarify the change in the tensile strength of the haulms stem depending on the height of the stem section, and therefore on the diameter.
Tаble 3
Breаking forces pf pоtаtо haulms along the аverаge diаmeter
Variety Average diameter, mm Breaking forces, N
average maximum minimum
Acrob 9,8 427 493 349
Lorch 8,4 417 433 349
Victoria 8,1 343 416 271
Cardinal 6,3 235 311 189
Santa 6,9 219 291 170
Work in this direction was carried out by a number of researchers. We repeated these works in order to supplement and clarify these indicators. In Fig. Figure 1 shows curves of changes in the temporary tensile strength of haulms depending on changes in the height of the section. From these data it is clear that with an increase in the height of the stem section, the temporary resistance decreases intensively, especially in the range of 0-180 mm.
In Fig. Figure 2 shows the change in the amount of haulms entering the combine over two meters of the machine's path. It is very variable and on average is 2.43 kg/m.
Thus, when designing haulm-removing working bodies operating on the principle of pulling or on the principle of separation from the stems, it is necessary to strive to ensure that the capture of the stems occurs as close as possible to the base and root. In this case, there is a
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complete guarantee that the stems will not be torn off.
16 I-------r
80 AO ISO 270 ,, 450
Fig.1. Chаnge in tensile strength оf haulms stem rupture pоtаtоes depending оn the height
of its section
251---------
1 234 5 6 7 8 Kr 10
m-■—
Fig.2. Vаriаtiоn curve оf distributiоn оf incоming haulm hаrvester (m) оn twо meters оf
mаchine path
The density and coefficient of friction of tubers and haulms are also necessary for the analysis and calculation of the parameters of the haulmping working body.
Based on numerous works [14], the density of tubers can be taken equal to 648 kg/m3, and haulms - 133 kg/m3.
The results of experiments to determine the coefficients of friction of haulms and potato tubers on various surfaces, carried out according to the existing methodology [14], are given in table 4.
Tаble 4
Frictipn cpefficients pf tubers аnd haulms pn various surfaces (pressure - own weight.)
Elements Definition Friction Movement Friction coefficients
condition surface speed m/s minimum maximum average
Peace Steel - 0,71 0,80 0,76
the soil 0,98 1,03 1,00
1,6 0,53 0,59 0,54
Tuber Movement Steel 2,4 3,2 0,51 0,45 0,58 0,57 0,55 0,54
Rubber layer 3,2 0,42 0,51 0,46
the soil 3,2 0,43 0,91 0,62
haulm Peace Steel - 0,47 0,74 0,57
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Rubber layer - 0,71 0,93 0,80
the soil - 0,67 0,96 0,80
Steel 1,2 0,60 0,84 0,73
2,4 0,63 0,76 0,71
Movement 3,2 0,55 0,68 0,63
Rubber layer 3,2 0,42 0,49 0,45
From the data given in table. 4 it follows that the coefficient of friction of both tubers and haulms on all studied friction surfaces at rest is 1.5 times greater than in motion. With the development of sliding speed, a noticeable decrease in friction coefficients is observed.
The highest coefficient of friction was obtained between the tuber and the soil, and the lowest - between the tuber and the rubber layer of the transport belt, as well as the haulms and the rubber layer of the conveyor. To calculate the coefficient of friction of the tuber on steel, it can be taken within the limits 0.5-0.6, conveyor rubber layer - 0,4-0,5, and for haulms -accordingly - 0.6-0.7 and 0.4-0.5.
Conducted research to study the physical and mechanical properties of potato haulms and tubers, such as lodging and orientation of haulms stems on the field, weight, breaking forces of haulms and stolons, friction coefficient allows us to correctly select and justify the installation location, shape and parameters of the haulms removing working body in a potato harvester.
Typically, the literature contains data only on lodging [1 -6, 14]. The direction of the stems is characterized only generally by the number of stems directed either across the bed or along. Intermediate directions are not taken into account. To carry out more complete comprehensive measurements, a special coordinator was designed and manufactured (Fig. 3).
The coordinator consists of 1 table and 2 vertical and 3 horizontal poles. In the legs of the table, 10 holes with a diameter of 14 mm and a pitch of 100 mm are drilled coaxially, into which pole 3 is inserted, thereby limiting a certain horizontal zone. The same 12 holes are drilled on the upper planks of the table in such a way that an angle of 30° is formed between each pair of holes relative to the center. When taking measurements, the table is installed in the middle of the grooves, as shown in the diagram. The horizontal pole is moved sequentially every 100 mm higher, starting from the bottom of the furrow, and in each zone the number of segments of haulms is counted. These data characterize the degree of lodging of the stems. After this, the number of stems is counted, located in sectors, for which the vertical poles are sequentially, starting from zero, rearranged for each subsequent division, limiting, as indicated above, an angle of 30°. These data characterize the directionality. Repeat the experiments 20 times along the diagonal of the field.
Fig. 3. Coordinator scheme
The results of these experiments show the average lodging and directionality of potato haulms stems for the varieties Lorch and Sante, it is clear that the largest percentage (23.5-38.2% for the variety Lorch and 25.6-35.7% for the variety Santa) of lodged stems is located in horizontal zones from 10 to 30 cm. To the right and left of the maximum, the indicators decrease and reach the following values: completely lodged stems account for 12.75% for the Lorch variety and 17.0% for the Sante variety, and in zones from 50-60 cm and above there are almost no haulms stems, although, as will be described below, the stems of the haulms exceed these dimensions in length.
The largest percentage of stems directed across the bed and close to this is in the sectors from 600 to 1200 and 240-300°, respectively 12.15-13.5% and 11.8-13.2% for the Lorch variety, 11.5- 14.6% and 10.77-13.1% for the Sante variety, i.e. the total is about 50%. If we also take into account sectors from 30° to 60°, 120°-150°, 210°-240°, then the percentage of stems deviated to the sides from the furrow axis reaches about 90%.
The given data give us grounds for the correct choice of the location of the haulm removal working body in the technological scheme of a potato harvester, especially one that uses a method of separation by size (screens with longitudinal bars, conveyors with transverse bars with large gaps between them).
In the middle of the technological process, or, in any case, immediately after the previous separating working body, when the stems of the haulms, as the mass passes through these working bodies, change their direction and are oriented along the combine, it is advisable to install a haulm removal working body with transverse rods
4. Conclusions
Conducted research to study the physical and mechanical properties of potato haulms and tubers, such as lodging and orientation of haulms stems on the field, weight, breaking forces of haulms and stolons, friction coefficient allows us to correctly select and justify the installation location, shape and parameters of the haulms removing working body in a potato harvester.
The maximum tuber dimensions are 102 mm in length, 75 mm in width and 56 mm in thickness. With an increase in the cross-sectional height of the haulms' stem, its temporary tensile strength decreases rapidly.
As a result of the work carried out on pulling potato bushes both from dug-up beds and from un-dug ones, it was revealed that from 30 to 70% of the tubers were removed along with the stems. Experiments have shown that the effort to separate the tuber from the stolon can be taken on average to be 3-8 N. For calculations, the coefficient of friction of the tuber on steel can be taken within the range of 0.5-0.6, on the rubber layer of the conveyor - 0.4-0.5, and for haulms - 0.6-0.7 and 0.4-0.5, respectively.
It is more advisable to install a working body with longitudinal gaps between the rods at the beginning of the technological process, since here there is the possibility of hanging on the rods, and therefore removing up to 90% of the haulms.
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UDK:625.08
