Fertilizer Distributor

Vertical Toothed Rotor Fertilizer Distributor Project promises to reduce the cost of the product by up to 40% compared to the dosers currently used.

In-line seeders-fertilizers are characterized by simultaneously depositing seeds and fertilizers into the soil. For this purpose, this equipment has dosing mechanisms, responsible for dosing the products.

Fertilizers account for around 25% of the costs of a crop. In this way, it can be said that the functioning of dosing mechanisms can affect the profitability of the agricultural enterprise, in addition to being decisive for the quality of the sowing process and, therefore, their performance must be evaluated under different working conditions.

Due to the great concern of producers in having a more uniform crop and obtaining greater productivity, a vertical toothed rotor type fertilizer dosing mechanism was developed which, according to Portella (1999), performed well above other compared dosers, with C.V. of 1,3% at its best dosing performance.

The fertilizer dosing mechanism, shown in Figure 1, is found in most European and Argentine seeder-fertilizer models.

The vertical toothed rotor, as shown in Figure 2, is characterized by a cylinder with equidistant teeth on its periphery. Fertilizers are distributed by being dragged by the rotor teeth. To obtain better uniformity, depending on the product to be distributed, the tines can be arranged in two alternating rows. The distribution flow occurs by varying the speed of the dosers drive shaft, which is obtained through speed variator boxes. 

The toothed rotor was designed with teeth equidistant from each other, providing a uniform flow for the fertilizers to be distributed, as shown in Figure 3.

Trials and tests

The doser tests were carried out at the company Stara Indústria de Implementos Agrícolas S/A, in the Research and Development Laboratory. The treatments were formed from a factorial arrangement, with three replications, within a completely randomized design. This experiment was repeated at three drive speeds, 30rpm, 60rpm and 90rpm, with three fertilizers. The observed response variable was the average mass flow rate of the doser, collected in 30 seconds, at the three speeds, with the three nutrients.

This methodology was adapted from Milan & Gadanha Junior (1996), which describe the procedures for flow regularity tests, used in the evaluation of broadcast fertilizer distributors, used to determine the dosage in each doser adjustment position of this type of equipment. .

For the purpose of analyzing the results, analysis of variance of the data was performed and the means were separated by the Tukey test with P < 0,05. To compare the performance of the new doser with the current doser with different types of fertilizer and speeds, the full amplitude was used. As the dosers have different flow capacities, the total amplitude was transformed into relative amplitude, which represents the percentage of dosage variation in relation to the doser flow when leveled longitudinally.

TEST BENCH

The test bench used to carry out this work was built by the Stara Prototype team, on the premises of the same laboratory. It basically consists of: support structure, drive structure and support for the doser. The material used for its construction was SAE 1020 carbon steel.

The function of the support structure is to serve as support for all other components of the bench, support for the doser that supports the fertilizer tank, and the entire transmission system.

The doser is driven by a 1 hp (735 W) electric motor, with a nominal rotation of 1.740 rpm, coupled to a 10:1 gear reducer, and a frequency inverter, which allows the dosers to be driven with rotations close to at 0rpm to 174rpm.

For the tests, the fertilizers urea were used, whose composition declared by the manufacturer is 45% nitrogen, and potassium chloride, with 60,5% potassium, and a mixture of the two fertilizers in a 2:1 ratio of urea/chloride of potassium. These fertilizers were chosen for their wide use as a source of nitrogen and potassium by farmers and their mixture aimed to observe the trend in quality distribution of mixtures of different nutrient sources with different physical characteristics.

Results

The results found in the tests carried out are presented in Table 1.

Considering that statistically the vertical doser is as precise as the commercial doser, which is a market reference, the doser that has the most affordable cost can be chosen. In a comparative cost analysis, the vertical doser proposed in this work cost around 40% compared to the commercial doser, which could justify future studies for commercial development.

CONCLUSIONS

A vertical toothed rotor fertilizer dosing project was developed, with three main objectives, simple adjustment, high precision and low cost, with all objectives being achieved. In tests compared to the market leader, the vertical toothed rotor fertilizer doser achieved similar flow rates. After carrying out statistical tests, it was concluded that the Vertical Doser is as accurate as the commercial doser. Therefore, the cost factor would be used for future decision making regarding its commercial implementation.

Fertilizer Doser Project

The doser design consists of a housing divided into two parts, (Figure 4.A.1 and 4A.2), joined by screws (Figure 4H), and made of nylon with 20% to 30% fiber. The Vertical Toothed Rotor (Figure 4B) is made from SAE 1045 material obtained by the microcasting process, the guide bushing (Figure 4C) is also produced by the microcasting process from SAE 1030 material. The vertical toothed rotor is guided by a toothed washer ( Figure 4D), which has the function of preventing fertilizer from leaking from the side of the doser. This washer is coupled to an injected polypropylene ring (Figure 4E) mounted on the housing, with the function of protecting it, absorbing the wear caused by the movement of the toothed washer. The lever (Figure 4G), when activated, transmits movement to the flow adjustment bar (Figure 4I), which axially moves the transmission shaft and, occasionally, increases or decreases the exposure of the channeled cylinder to the mass of fertilizers. The bottom (Figure 4F), made of injected polypropylene, has the function of regulating the size of the exit hole, depending on the flow of fertilizers being dosed.

 

Bruno Freitas Dalmagro, José Antonio Portella, UPF

Article published in issue 165 of Cultivar Máquinas.