Theoretical substantiation of parameters of the planetary fruit separator

. The work is devoted to the theoretical substantiation of the parameters of the planetary fruit separator of nightshade vegetables both in direct and reusable ways. The article has a theoretical research character expressed in the fact that the analysis of the method of harvesting nightshade vegetables is theoretically given. There was determined the main theoretical trend of equipment development and advancing its design to improve the quality of its work. There were given the type of the proposed design, its theoretical description and the flow of technological process. As a result of the work done, the design of the device for reusable nightshade vegetables harvesting with proposed working bodies is presented. The conclusions present the main results achieved so far.

Whence L = (1) In order to eliminate the loss of fruit from rolling on the rollers, the angle α should be less than the angle of rolling the fruit on the rolls αск, that is α Considering that h = Rδ, in final type has L = Thus, the length of the drums depends on both the physical and mechanical propertiesdimensional characteristics of plants and the angle of fruit rolling, and on the design parameters of the fruit separator. Higher plants require an increase in the length of the drums or an increase in the angle of α. Also, an important factor in the harvesting process is the diameter of the fruit separator drum. Considering the kinematics of the planetary drum, we note that at any connection of the centers of the cylinders by straight lines we get a regular polygon which number of sides is determined by the number of cylinders and the angle between the center of the drum Об and the centers of circumference of the adjacent rollers ОВ1and ОВ2 by the angle ε is 360/n ( Figure 2).
The side of the polygon ОB1 ОB2 (Figure 2) can be expressed as where RB -radius of roller; Z -gap between rollers.

Fig. 2. To determination of number of rollers
The gap between the rollers should exclude the ingress of small fruits and parts of the plant into the drum.
The radius of the rollers is comparable to the size of the average fruit (choose 20-25 mm). Defining "a" -for the selected number of rollers, define the perimeter P of the polygon, and the radius of the circle on the centers of the rollers from it.
where Rцов-radius of roller center circumference. Whence In this case the diameter of the drum will be equal to The relationship between the number of rollers and the diameter of the drum for Z=25 мм,RB=20 and 25 mm was shown in Figure 3.
The dependence of D6 on n is a weakly expressed sinusoidal dependence, which can practically be considered close to proportional.
Increasing the number of rollers and their radius leads to an increase in the diameter of the drum. In the process of planetary fruit separator the essential condition is not to tighten the fruit of a given size in the gap between the rollers of adjacent drums.
To ensure this, it is necessary that the tightening angle is greater than twice the angle of friction of the fruit on the surface of the rollers.

2φ
(5) where αзат -tightening angle; φ -angle of friction and slide. The angle of tightening αзат is determined ( Figure 4) by intersection of perpendiculars recovered at the contact points to line radii which is common for rollers and the fruit.
Express the angle αзат from the quadrangle of АОnВС ( Figure 4). αзат + 90 + 90 n -the number of rollers Drum diameter, mm Determine the gap between the rollers. In the expression (6) parameters are Rв and Rn, the latter must be equal to the minimum value of the radius of harvested fruit, i.e. Rв and Rn. This is justified by the fact that at the same values Rв and Z the decreasing the fruit size leads to a reduction of the tightening angleαзат, that is, in this case increases the possibility of fruit tightening between rollers of adjacent rollers ( Figure 5). As for the choice of the gap Z, provided 2 = Z или 2 <Z small fruits will pass through the gap between the rollers of adjacent drums and after further growth to be removed at the subsequent passage of the harvester. This is the essence of reusable cleaning.
Consider the case when the rollers of adjacent drums are installed without displacement relative to each other. In this case, the minimum gap between the rollers of adjacent drums will be the case when the centers of the rollers will lie on the line O1O2, connecting the centers of the drums, and the gap will be equal to O1O2 -2Rб, where 0102 -center-tocenter distance between drums, aRб is the radius of the drum. The size of the gap between the drums in this case is determined by the diameter of the main stem of the plant's bush.
However, such an arrangement of rollers of adjacent drums of the fruit separator eliminates the oscillation of stalks required for fruit separation, this dramatically increases the damage and fruit losses on the ground.
To ensure the oscillation of the stem, the rollers of adjacent drums are shifted relative to each other at an angle equal to half the angle between adjacent rollers on the drums. In this case, the minimum distance between the centers of the circles of the rollers involved in the process of rolling the stem and its oscillations, and therefore the gap between them increases somewhat against the original case, but will be the same at the extreme positions of the stem during its oscillations.
The stem takes the extreme position when the center of the circle of one of the rollers, regardless on which drums is located on the O1O2 line connecting the centers of the drums' circles. In the intermediate ones between the extreme positions of the stem, the gap between the rollers of the drums involved in the process of stem rolling does not change.
This is because moving in the zone of oscillation of the stem in circles at identical angular velocities of the drums when turning by the same angle the approximation of one of the rollers to other drum, is compensated removing the roller of other drum. Therefore, to determine the gap between the rollers of adjacent drums, it is sufficient to determine it for the position when the center of the circle of one of the rollers of any drum is on the line connecting the centers of the drums O1O2.
In expression (7), it is necessary to take only positive Z values, since negative values have no sense.
At the accepted parameters of the drum Rв, Rцов, Zб, the value of the gap between the rollers of the lower drums involved in the process of rolling the stems will depend only on the value of the inter-center distance of the drums.
To determine this distance, and therefore the range of permissible values Z, we make the following assumptions -the gap between the adjacent rollers of one drum and the opposite roller of the other drum should be equal to the average diameter of the rolled stem. Figure 6 shows the position of the stem at the time of its contact with the rollers of adjacent drums.
Here the unknown is ρ'. The stems are in contact with the rollers at the points L and N. Let us denote the distance from the center of a circle of drums to those points in terms of ρ and the projection of this value on the line О1О2 via ρ', which should be determined.
From ∆O1OвN by the sine theorem In this case, with a stem diameter of 10-14 mm, the gap Zб will be equal to this value, and the center-to-center distance between the drums will be OO1= 90+10+25+75 =200 mm. ОО1 = 90+14+25+75 =204 mm. So, the interval of admissible values O1O2 is 200-205 mm. Dependencies between O1O2 and Z were shown in Figure 9. From the data of Table 1, it follows that an increase in O1O2 leads to an increase in the gap between the rollers of the drums in the zone of contact with the stem according to the dependence close to directly proportional.
For the range of permissible values Z (200-250 mm) we determine the angle of tightening by the expression (6) for fruits of different diameters. Take into consideration that cos(-α) = +cos(α). It excludes changing the minus sign to the plus sign in the expression (6). The calculations are done for the unit which radius of rollers are Rв=25 mm; at Z=21,l; Z=25,l and the radius of the fruit Rn= 10, 15, 20, 25 and 30 mm. The results are shown in Table 22. The graphical interpretation of the data is shown in Figure 7.
The minimum value of the tightening angle αзат will be when the angle μ reaches the maximum value, and it is possible when cosμ = 0, and the angle itself will be 90°. In this case, the minimum value will be α3=180 -90 = 90° cosμ, in its turn, will be equal zero at Rn= Z. It is determined in Figure 7. Thus, fruit with a diameter of Дп = 2Rn<Z will freely pass into the gaps between the drums for re-harvesting, and other larger ones, will not be delayed between the drums, provided αзат> 2φ or φ < 45°.
Thus, the planetary fruit separator with following parameters: diameter of 170-200 mm; number of cylinders -6 PCs; roller diameter -40-50 mm, center-to-center distance of 200-205 mm, will be to separate the fruits of a radius larger than 25 mm. Fruit of smaller radius pass through the device and continue their vegetative growth, under the condition that the coefficient of fruit friction on rollers will not be greater than one.