International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Mechanized harvesting of sesame is not solved problem in many places in the world because of significant losses of seeds. The essence of the problem consists in the fact that sesame capsules release seeds due to a slight mechanical impact or by the wind when ripening. For solving the problem in Bulgaria the sesame research is conducted in two directions. The first is selection sesame varieties, suitable for mechanized harvesting and the second is adaptation of existing equipment and development of new for harvesting sesame seeds. In 2015 has been developed a method for assessment the susceptibility of sesame genotypes for mechanized harvesting of the seed. The method is based on an impact of a pendulum and on calculation of three indices. The first index is a criterion for self releasing of seeds from capsules, the second index is a criterion for retention seeds in capsules and the third index – for strength of the link between seeds and placenta. The method was applied to assess the susceptibility of sesame varieties for mechanized harvesting as well as to choice parental pairs in the selection of new sesame genotypes. A lot of new sesame genotypes have been selected and they have higher indices then existing. Representative studies for mechanized harvesting the seed have been done through five different technologies and machines in Bulgaria. The best results are shown by the two new developed devices. The first is for feeding sesame stems into harvesting machine. It squanders 3.4 times less sesame seeds than the grain harvester Wintersteiger – Hege 160 at parallel harvesting of hybrid f3/361-6-3 at seed moisture content of 8.9%. The second is for inertial threshing of sesame seeds. It threshes over 95% of seeds of non-shattering varieties Aida and Nevena without reducing their germination at seed moisture content from 12.2 to 13.3% while the conventional thresher decreases germination with 27%. The productivity of the conventional thresher is 1.4 times higher than that of the inertial thresher. The total power consumed by the inertial thresher is 4.81 times smaller than by the conventional thresher, because it does not deform stems and capsules during operation.

After mechanized whole-plant threshing of sesame a mixture of seeds, seed-cases and stems is obtained. The separation of the seeds is done by means of a unit, consisting of a sieve and a fan with combined movement and adjustment of the air flow rate and the slope of the sieve cradle. The results of the testing of the separation unit with different crop shows the possibility to obtain sesame seed purity 94 … 97%.

A comparison has been made of four technologies for mechanized sesame harvesting in conditions of Bulgaria. The first is one- stage harvesting with grain harvester. The second is two- stages whole-plant harvesting. The third is two- stages harvesting where the first stage is collecting the sesame capsules and the second – threshing the capsules after draying. The last technology is one – stage seeds harvest- ing while the plants are "on roots". The first technology has been recommended for large and flat fields. The third technology has been the most suitable for production of seeds. The forth technology is suitable for small-size fields. For such conditions has been elaborated a prototype which harvests sesame at a humidity which is twice times higher than the optimal for grain harvester and at several times less consumption of energy.

In the following, well-founded a method and is proposed preliminary version of the device for stationary whole plant threshing of sesame. Presented a methodology for calculation of basic geometric and kinematic parameters of crushing and grinding mechanism consists of a pair of metallic corrugated rollers, for threshing of sesame.