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Section 4. Mechanical engineering
Bakhadirov Gayrat Atakhanovich, scientific adviser, professor Umarov Bekhzod Turg'unpo'latovich, doctoral student, Ferghana Polytechnic Institute, E-mail: bexzodumarov@mail.ru
BASICS OF CALCULATION OF CERTAIN PARAMETERS OF THE BELT DRIVE OF THE MACHINE FOR SORTING OF POTATOES
Abstract: The article gives data on the calculation of machine design parameters for potato sorting, using known methods for calculating the dimensions of shafts and belts. Keywords: potatoes, sorting, belt drive, pulley, shaft, tension, voltage.
Potatoes are cultivated in 130 countries on an area of more than 18 million hectares, where annually more than 300 million tons of tubers are harvested [1].
At present, the sorting of potatoes on farms involves considerable labor costs due to low mechanization and electrification of the technological process. Serial production of machines for sorting potatoes has practically ceased due to their high cost and low reliability of work, due to the large number of rotating and failing parts, therefore, the share of manual labor in sorting potatoes has sharply increased in farms. The use of obsolete, worn and energy-intensive equipment is not effective. The disparity of prices between agricultural products and prices for equipment and energy requires the improvement of technology and technical means in the production of agricultural products [2].
In this regard, the creation of machines for sorting potatoes with high technical and economic indicators is an urgent task [2].
We propose a new design of the sorting machine, with the purpose of qualitative sorting of potatoes according to external dimensions, taking into account the size-mass properties of tubers of cultivating potato varieties [3].
A potato sorting machine, containing conveyors for loading and removing the potatoes isolated on the fraction, a sorting surface formed by infinitely closed
flexible elements enveloping pulleys of the same diameter mounted on transport shafts with the possibility of axial movement, hinged parallelograms for axial movement, characterized in that the infinitely closed flexible elements of the sorting surface are arranged on pulleys diverging from the middle to the edges of the sorting surface in the direction of travel, the pulleys being mounted on the transport shafts in alternating sequences, one being free, and the other being kinematically associated with transport shaft, in turn, the transport shafts are provided with a drive for communicating to them different speeds of rotation [3].
It is necessary to calculate its basic parameters, for reliable operation of the machine. The basis of the mechanism of the machine is the belt drive (fig. 1). Determining the forces and dependencies between them, you can determine the stresses in the belts, the required shaft sizes. Consider, for transmitting motion from the engine to the belts through a reduction gear and a first pulley. The branch between the 1st and 2nd pulleys is the leading one (fig. 1).
According to Euler's formula [4, 5]:
0,= Q (1)
The tension in the branches connected to the tension roller is mutually equal [7]:
Q2 = 0, = N = n2 (2)
BASICS OF CALCULATION OF CERTAIN PARAMETERS OF THE BELT DRIVE OF THE MACHINE FOR SORTING OF POTATOES
Figure 1. Strength in the branches of a sorting machine belt
where, Q, Q^ Q, Q - respectively, the tension in the branches, N1, N2 - the tension obtained from the tension pulley, e - the base of the natural logarithm, y - the coefficient of friction between the pulley and the belt.
The values of ya and yft will always be positive. Therefore, the relationship between forces will be:
Q > Q (3)
Suppose that this shape (fig. 1) is an isosceles trapezoid, this allows us to determine the following dependences between the angles a, ft, 7:
a = n - y, ft = y (4)
Because of the small value of ft and y, we take yft — 0. Thus:
Q2 - Q - Q (5)
To operate the belt in 1 and 2 pulleys without sliding, it is necessary to satisfy the following inequality [4]:
Qo >-
+1
e -1
(6)
where, Q0 is the initial tension force transmitted to the belt through the tensioning roller-3 (Q0 = N1 = N2), F-force is the generated torque transmitted to the pul-ley-1 from the motor through the reduction gear.
In the work of this mechanism from the centripetal force generated in the branches will be the following [4]:
Qv =1 v2 (7)
g
where, q is the weight of one running meter of the belt, N/ m.. v is the linear speed of the belt, m/s.
In the work of the mechanism, the linear speed of the belts will be low: v <1 m/s. The weight of one running meter of the belt is not large. Therefore Q — 0.
It is possible to determine the forces acting on the shaft and its supports with the 1 and 2 pulleys installed according to the formula [4]:
R = R =VQ2 + Q2 + 2Q, Q2 cosy (8)
Determine the stresses in the belts. The greatest stress occurs in the leading branch between pulleys 1 and 2, and it consists of o,1 arising from Q and c of the formation in the part of the belt that runs around the pulley surface [4]:
Q1
0,= — =
Qo
S
2S
= 0
0
D
(9)
where, E is the modulus of elasticity, S = bS is the cross-sectional area of the belt, S is the height of the profile of the belt, D is the diameter of the pulley (fig. 2).
Figure 2. The diagram of the envelope forces in the belt
Thus, the voltage in the leading branch of the belt has the following form (fig. 3) [4]:
^max =°0 +Y + (10)
where, crF = — - is a useful strain. F S
Due to voltage increase, the voltage arising from the initial tension increases the useful voltage [4]:
= 2*. ^ (11)
It is impossible to increase without limit the value of a, because an increase in a will lead to a decrease in the
O o
strength of the belt [4].
Figure 3. Stress diagram in the branches of the belt
In the state of motion transmitting to the 2' pulley from the electric motor through the reducer, the branch between the 2' and 3' pulleys will be leading. Thus, taking into account (5), the ratio between the tension forces in the branches 2' - 3', 3' - 4', 4' - 1', 1 ' - 2' is as follows:
Q.2 - Ql3 - Q.4 > Q.'i (12)
and
QL2 = Qh (13)
Depending on the design of the machine, the initial tension force transmitted to the belt through the tensioning roller-3' will be Qg = Q0, but the forces forming the torque transferred to the 2' pulley from the elec-
tric motor through the reducer will be F F. For this reason, the tensile forces and stresses in the branches 1 of the belt do not match the amount of tension and tension in the branches of the belt. You can choose the desired belt size and pulley diameter to the maximum calculated values.
Thus, we can draw the following conclusion: The necessary dimensions of the shafts are selected with a certain number of pulleys, the resulting motions from both shafts and belts of the enveloping pulleys, determining the forces acting on the shafts according to the formula (8) [6].
References:
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2. Gilvanov V. F.. Development of self-oscillating linear asynchronous electric drive of a machine for potato sorting: the dissertation Author's abstract on competition of a scientific degree of the Cand.Tech.Sci. Izhevsk,- 2012.18 p.
3. Bakhadirov G. A., Sabirjanov T. M., Umarov B. T., Bakhadirov K. G. Sorting machine. Patent. Republic of Uzbekistan. № FAP 01241. State Patent Office of the Republic of Uzbekistan, Official Gazette No. 10 (198),-2017.
4. Sulaymonov I. Details of the machine / I.Sulaymonov: Tashkent- "O'qituvchi",- 1981.- 303 b.
5. Nosirov S. Completion of course project on "Details of the machine" / S. Nosirov: Tashkent - "Yangi asr avlodi",-2008.- 218 p.
6. Mansurov K. M. Material Strengthening Course / K. Mansurov: Tashkent- "O'qituvchi",- 1983.- 498 p.
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