Development and Evaluation of a Semi-automatic Cucumber Seed Extractor

According to FAO, gherkin and cucumber have been cultivated in about 2.23 million hectares of farmlands around the globe, and about 78000 hectares of Iran agricultural fields have been devoted to gherkin and cucumber cultivation. However, large amounts of the cucumber seeds required in Iran have been imported from abroad. Fortunately, some Iranian agricultural companies have been focused on seed production recently. Therefore, there is an opportunity to develop seed production equipment such as seed extracting machines.There are two types of cucumber seed extractors: bulk seed extractor and single fruit extractor. The bulk seed extractor is suitable for extraction of large amounts of seed on the farm, while the single fruit extractor is suitable where seed production is limited to greenhouse seed-producing facilities which are mostly used for controlled pollination of the crop.Due to the high price of imported seed extractors, especially after increasing the price of foreign currencies, production of these machines within the country is economically rational; therefore, the aim of this research is to develop and evaluate a single fruit cucumber seed extractor for small and medium-size seed-producing greenhouses.

The cucumber seed extractor was designed semi-automatically. The criteria for designing the machine were as follows: 1- usage of the single fruit seed extraction method, 2- the possibility of simultaneous usage of two operators, 3- automatic discharge of the extracted seeds, 4- the possibility of the height variation of the machine, 5- the possibility of the emergency shutdown of the machine, 6- the possibility of the angular velocity variation of the machine helix.The working element of the machine was the rotating helix that can extract the fruit seeds and leave the fruit's outer skin mostly intact for easy disposal of fruit remains from the greenhouse. A 1 hp, 3 phase electric motor was used to drive the machine via the belt and pulley transmission system. For the smooth start and stop of the machine, and the possibility of angular velocity variation of the machine helixes, an electronic driver was used for the motor.To design the machine helix, the dimensions of the examined cucumber were measured first (i.e., cucumber length and diameter); then, according to the physical and mechanical properties of the fruit, the prime mover and transmission system of the machine was designed. Finally, the fabricated machine was evaluated using some mechanization criteria.

Some of the results are as follows:The total torque required to drive the machine was 3.394Nm.The electric motor power should be higher than 0.284hp; furthermore, in order to have a wider angular velocity span for the rotating shaft, a 1hp electric motor was installed on the machine.The diameter of the rotating shaft was calculated to be 15mm.The seed extracting machine could be used instead of 15 workers of the manual seed extraction method.The rate of seed extraction using the machine was 30781 kg ha-1.The efficiency of seed extraction using the machine was similar to that of the manual method.The emergence percentage of seeds obtained by the machine was similar to that of the manual method.The amount of crop calculated from the concept of economical break-even point was 7 tons.

In this study, an apparatus for mechanized extraction of cucumber seed was designed, fabricated and evaluated. The working element of the machine is the extractor helix that is rotated via the belt and pulley transmission system, which is activated using a 1 hp, 3 phase electric motor. For smooth start and stop of the motor, as well as the possibility of angular velocity variation of the machine helix, the motor was equipped with an electronic driver. Utilizing an emergency shutdown switch, the machine can be protected from unforeseen emergency situations. After using the machine for 6 months, it was recognized that strengthening the extractor helixes was necessary. According to the results of this study, using the machine led to 15 person reduction in the labor needs of the manual cucumber seed extraction method. Moreover, the amount of crop calculated from the economical break-even point was 7.7 tons.