Analysis of calculation pressing force of raw cotton to the surface of dielectric drum separators
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Jumaniyazov Kadam, Doctor of Technical Sciences, professor
Djuraev Anvar Djuraevich, Doctor of Technical Sciences, professor
Rakhmatullinov Farrukh Faridovich, a senior fellow researcher, Tashkent Institute Textile and Light Industry, E-mail: fara_tashkent13@mail. ru
Analysis of calculation pressing force of raw cotton to the surface of dielectric drum separators
Abstract: The article provides a new design of the dielectric separator for sorting cotton seeds of raw cotton in the degree of maturity of the fibers. There were discussed in detail the principle of operation of the proposed design of the dielectric separator. The analysis ofdesign models to determine the force pressing cotton seeds in their longitudinal and transverse locations in the area between the electrodes of the dielectric drum. The analysis of the formulas for determining the electric force pressing cotton seeds to the surface of the drum which for the considered two options of the location cotton seeds in the area between the electrodes of the separator. Analyzed estimated parameters of the separator and required design values cotton seeds pressing force to the surface ofthe dielectric separator bowl. Noting the relevant calculation results with the results of preliminary experiments in the laboratory.
Keywords: dielectric separator, sorting, fiber, maturity, cotton seeds, raw cotton.
motion of the particles and formation of the final product. The first step determines the initial conditions of entry ofparticles in an electric field, the second — the amount ofelectric power the electric field in the raw cotton. In the third step shown character movement ofseed cotton by the action of the resultant of the applied forces, and the fourth — is determined by the traj ectory of the seed cotton, after separation from the working body. The seed cotton to the actuator is usually solved by constructive-regime parameters of the supply unit solutions.
The quality of the resulting yarn depends on the maturity of raw cotton fiber. If the yarn obtained from fibers of cotton with different maturity, the yarn turns nonuniform and lower specification [1, 89−120]. Therefore, used different design separators that allow sorting ofraw cotton fiber maturity [2- 3]. We have developed a new design of the dielectric separator.
It should be noted that during the sorting of raw cotton fibers at maturity can be divided into four phases: feeding, charging, setting in
JJ /Nx- h- ^XgX
// L B jsq
y ! x
d S S L
Fig. 1. Calculated circuit: a) to determine the electrical force of attraction of the seed cotton at its lengthwise location in the space between the electrodes- b) to determine the electrical force of attraction of the seed cotton at its transverse disposition in the space between the electrodes
Section 7. Technical sciences
Principle dielectric sorting based on the action of the electric field of opposite polarity electrodes on raw cotton according to their quality indicators associated with the physical properties. Action field on raw cotton primarily estimated amount of electric power arising from the internal physical processes in the particle and raw cotton [4, 98−103]. To determine the electric force pressing the electrodes of different polarities of raw cotton in the insulating separator drum, we assume that seeds of raw cotton (the tough part) has an enlarged form with a radius R, and Rs2. Seeds may be located in the interelectrode space along the long axis (Fig. 1a) and transversely (Fig. 1b) cylindrical electrodes. Assume also that the electrodes filed a constant voltage U, that is between the electrodes has a direct current electrostatic field. Power of the electric induction flux lines emanating from the positive electrode, penetrate the insulation of the electrode layer with a thickness of d, the lower part of the volume of the seed cotton along the path length Ic, the insulation layer and the negative electrode conductor shorted to the negative electrode. As a result of polarization on the outer surface of the insulating layer of the positive electrode layer is formed of positive charges, and the facing surface portion of the seed cotton — a layer of negative charges -Q. On the opposite side of the seed cotton surface facing the negative electrode layer is formed of positive charges +Q
We assume that the electric field between the contacting surfaces of the elementary layers of insulation and the seed is uniform because of their smallness. The left part of the seed polarized by the electric field of bipolar electrodes is attracted to the positive electrode force, and the right side — with F to the negative electrode.
Total electric polarization contact force is the seed of the electrodes:
F = F- + F-. (1)
The magnitude of the resulting electrical force, since the symmetry of the system, the longitudinal arrangement of the seed in the interelectrode space is equal to (Fig. 1):
F = 2 F+ cosa
where a = arccos^l -_(R3 + 5)/ (+ Rc) — corner placement particle, degree.
Here Rc = b /2 — minor axis of raw cotton, m.- 8 — half of the gap between the electrodes, m.
However, according to  electric contact force of raw cotton seeds to the surface of the dielectric drum is determined from the expression:
sssU (sc — l) SnU2 cos a
2 (s0Rc sin a+scd)2
where Sn — polarized area of cotton seeds one electrode m 2- U — voltage between adjacent electrodes- s0 =8,85J0−12 F/m — the dielectric constant- sc, su — the relative permittivity of seed cotton and the insulation layer-
d — the thickness of the electrode insulation, meters. In the second variant the location of the seeds of raw cotton (Fig. 1 b) electric force pressing seed 3 depends on the angle a with respect to location of the seed 3 electrodes 2 drum 1. Thus from A COB:
sin a =
Accordingly, from the A AKC using the cosine theorem, we have:
KC2 = ((+ Rc 2) = CB2 — 2 (+ Rc 2) CB cos p. (5) Substituting (4) into (5) (3 + a = ^ given after some transformations:
a = arcsm
KC2-(+ Rc 2)2 + 2 (+ Rc 2)(+S) Using the method for determining the electrical force pressed against the seeds of raw cotton to the drum is following expression:
1) SUU2yjKC2 -(Rc2 -Sf
KC 2-(R + Rc 2)2 + 2 ((+ Rc 2)((+ S)
In order to calculate the electric force pressed against the seed will take the following parameters of the average pubescent cotton seed: length a = 1240−3 meters- width b = 6. 4−10~3 meters- R = 3. 3−10~3 meters. Electrodes made of cables PK-75−4, parameters are: su = 4,0- Rs = 3,65 -10−3 meters- R1 = 2. 6−103 meters.
When applying to the electrodes a voltage of 3−4 kV. electric power value becomes comparable with the force of gravity G of the seed. When F/m magnitude electric power at a voltage of 4.0 kV. electrode is 40% gravity seed. Pressing force is applied in the range (400−1900)-10-s N first embodiment arrangement of seeds of raw
0,03 0,024 0,018
?0Rc 2 (+5)
yjKC 2 -(+ R 2)2 + 2 (+ Rc 2 +5)
cotton in the interelectrode space. In a second embodiment, the location of the seeds of raw cotton (Fig. 1b) electric contact force is reduced to (320-l650)-10−5 N. Therefore, for normal operation of the dielectric separator requires an application electrodes 4. 0−5.0 kV. Preliminary results sufficiently confirm the theoretical results of the research.
Thus, the new design of the dielectric separator for sorting seeds of cotton fibers at maturity- formulas for determining the electrical contact force seed cotton to the drum when the longitudinal and transverse arrangement of seed cotton in the interelectrode space of the separator- recommended design values.
0,012 0,006 o
2 3 U, KB
0,04 0,032 0,024 0,016 0,008 0
Fig. 2. The dependence of the electrical force of attraction of cotton seeds to the surface of the drum by varying the voltage electrodes: 1 — Ec = 5- 2 — Ec = 7- 3 — Ec = 10- 4 — Ec = 20. Fig. 2a — Sn = 0. 2 m 2, a = 30°- Fig. 2b — Sn = 0. 30 m2, a = 30°- Fig. 2c — Sn = 0. 35 m 2, a = 30°
To analyze the influence of parameters justification voltage electrodes on the power of attraction of raw cotton seeds is the surface of the drum. Fig. 2 presents a graph of changes in electrical pressing force of raw cotton seeds to the surface of the drum when changing the voltage electrodes.
The graphs in Fig. 2a. it is seen that with increasing of voltage electrodes up to 5.0 kW, the pressing force increases non-linear patterns to 0. 0210. 0245 N at Sn = 2. 0−10−5 m 2, a = 30°. With increasing in the polarized area (contact area) seeds to 3/5−10−5 m 2 at a = 30° the force of attraction of seed is doubled and reaches 0. 0360. 045 N at U = 5 kV.
It should be noted that the emerging intensity of electric field Ec is also affected to change F3. So with increasing intensity from 5.0 to 20.0 attraction force increases to 0. 005 N at Sn = 2. 0−10−5 m 2 and a = 30°, and when Sn = 3. 5−10−5 m2 F increases to 0. 016 N.
This means that increasing in the area of the polarization of raw cotton increased in proportion to the intensity of the effect of the force of gravity on the seeds of raw cotton in the insulating separator.
From these expressions (3) and (7) for calculating the attractive force seed raw cotton to the surface of the drum, and from the 0,03
0,024 0,018 0,012 0,006 0
& gt- г
2 3 Ц KB
circuit (Fig. 1) that with increasing angle of the raw cotton in the working area attraction force decreases as the center of gravity of raw cotton seed is removed from the surface of the snare. Built graphics depending also to confirm this pattern. Fig. 3 shows graphic patterns of changes in electrical contact force to the raw cotton seed drum surface by changing the voltage electrodes at an angle of arrangement of raw cotton seed 30° (a), 45° (b), 65° ©. Thus, by increasing the voltage of the electrodes up to 4.5 kV. and Sn = 2. 5−10−5 m 2, E = 7.0 electrical contact force reaches 0. 024 N for a = 30°, and
with increasing angle a = 45° force F3 comes to 0. 021 N. Accordingly, when a = 65° pressing force of raw cotton seeds to the surface of the drum is reduced to 0. 0112N.
Therefore, the decrease is considered appropriate angle a, and the recommended orientation of the seed raw cotton in the working area must be such that the angle a exceeds 25°^45°, with Uia = 4. 04.5 kV. To this raw cotton seeds must be positioned along the electrode, rather than perpendicular to them.
According to the scheme in Fig. 3 b. pressing force of raw cotton seeds to the surface of the drum is reduced to 1.2 4 1.3 times the location of the seeds of raw cotton under the scheme in Fig. 3a.
0,016 0,012 0,008 0,004
0,014 0,0112 0,0084 0,0056 0,0028 0
У. /?у 1
Fig. 3. The dependence of the electrical force of attraction of raw cotton seeds to the surface of the drum by varying the voltage of the electrodes at the location of the seeds of raw cotton at a different angle: 1 — Ec = 5- 2 — Ec = 7- 3 — Ec = 10- 4 — Ec = 20. Fig. 3a — Sn = 0. 25 m 2, a = 30°- Fig. 3b — Sn = 0. 25 m 2, a = 45°- Fig. 3c — Sn = 0. 35 m2, a = 65°
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