Data/hora: 20/06/2024 03:38:58

Biblioteca(s): 	Embrapa Soja.	
Data corrente: 	15/07/1998	
Data da última atualização: 	01/06/2006	
Autoria: 	MESQUITA, C. de M.	
Afiliação: 	EMBRAPA-CNPSo. Londrina, PR.	
Título: 	Mechanics of soybean thereshing.	
Ano de publicação: 	1989	
Fonte/Imprenta: 	Lincoln: University of Nebraska, 1989.	
Páginas: 	142p.	
Idioma: 	Inglês	
Notas: 	Ph.D. Dissertation.	
Conteúdo: 	Research findings on mechanical properties related to soybean threshing has suggested the inefficent use of considerable amounts of energy by the conventional methods of harvesting. This research intended to prove that there is potential to improve harvesting equipment by taking advantage of the shattering characteristic of soybeans. Two experimental devices were designed, built, and tested to study the effects of mechanical impact and mechanical rubbing (friction and compression) on threshing soybeans including mechanical seed damage. The energies required by pods to be threshed and to operate both devices were measured and compared with the energy used by conventional combines to thresh soybeans. The impact device was basically made of two parallel walls suspended from a supporting plate which moved in a reciprocating motion beating the plants which were driven between them to simulate a harvester moving over a row of plants. The rubbing device was composed of two endless belts mounted on four vertical rollers with adjustable spacing between them. Similar to the impact device, the plants were driven into the front gap simulating the movement of the device over the row of plants. The impact device threshed 92.5% of the soybeans with the combined effect of the 520 rpm crank wheel speed and the 10% moisture content pods. The threshing efficiency with the 520 rpm crank weel speed was around three times higher than that obtained with the 360 rpm speed. Threshing efficiency increased significantly with decreasing of pod moisture content. Seed damage, although had presented some high levels, did not affect significantly the levels of vigor and germination. There was a trend to increase the mechanical damage with an increase in the impact speeds and a decrease of pod moisture content. The estimated energy was 0.0127 J per pod to be shattered at 10% moisture content. The kinetic energy available from the device per impact or half revolution of the crank was 50 J. The energy required to drive the impact device was 110 J during 0.05747 s (time taken for crank's half revolution). The energy used by threshing mechanisms of conventional combines was found to be around 30 times greater than the total energy absorved by soybeans from the impact device. The impact device required 20% less energy when compared to the threshing energy requirements of conventional combines. There was no significant effect of belt speeds on the threshing efficiency of the rubbing device. The threshing efficiency at 21% pod moisture content was significantly lower than that at 10 and 16% moisture content. The threshing efficiency at any speed at 10% moisture content pods was over 92,5%. There was no significant mechanical seed damage. The energy required per pod to be shatterred by the rubbing device was 0.0123 J during 0.023 s. The energy required by the rubbing device was 18.5 J. The energy used by conventional combines was: more than 100 times higher than the required by the pod to be shattered, 12 times the energy required by a soybean plant (pods and stem), and more than 4 times the energy required by the rubbing device. The conclusions concerning to the impact device were: 1 - The impact device threshed soybeans satisfactorily at impact speeds adjusted to the moisture content of the pods. Pod moisture content and velocity of impact were important sources of variation for threshing efficiency. 2 - The mechanical damage to the seeds did not affect significantly the vigor and germination despite the trend to increase with increasing impact speed and decreasing moisture content. 3 - The impact device demanded 25.52 MJ/ha, while the total energy required or absorbed by pods at 13% moisture content was 1.044 MJ/ha. 4 - Although the impact device saved about 20% of energy when compared to the threshing mechanisms of conventional combines, there is potential to improve it by reducing its mass or by using driving mechanism other than crank system to transmit impact requiring less energy. The conclusions fore the rubbing device were: 1 - The rubbing device presented a remarkable threshing performance. The threshing efficiency oh the rubbing device was very high at belt speeds from 10.8 to 13.4 km/h and pod moisture contents from 10 to 16%, and satisfactory at those speeds and pod moisture of 21%. Pod moisture contents and belt speeds were not limiting factors in the rubbing process. This was an important characteristic as the device worked in a wider than the normal range of pod moisture content for current harvest methods. 2 - The levels of mechanical damaged seeds were equal to the control (hand threshed) treatment. This result, obtained at belt speeds higher than normally used ground speeds, suggests that ground speeds could be still increased with further development of this system. 3 - The estimated energy required by the rubbing device was 7.4 MJ/ha while the estimated energy required by pods and stem together was 2.5 MJ/ha and the energy required by pods only was 0.252 MJ/ha. 4 - Despite the fact that the energy requirements of the rubbing device was four times less than that of conventional combines, it still wasted a lot of energy as compared to the energy required by plants (pods and stems), and required by pods alone. The large difference between the energies required to thresh the plant (pods and stem) and to thresh the pods alone suggests that future improvements of soybean harvesting equipment should consider the possibility of avoiding the handling or processing of the stems along with the pods. The overall results seem to prove that there is potential to improve soybean harvesting equipment if the machines were designed to take advantage of the shattering characteristic of the pods.	
Palavras-Chave: 	Agricultural machinery; EUA; Mecanica da trilha; Soybean threshing; USA.	
Thesagro: 	Colheita; Engenharia Agrícola; Mecanização Agrícola; Soja.	
Thesaurus Nal: 	agricultural engineering; harvesting; Nebraska.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Soja (CNPSO)	
Exemplares: 	CNPSO - (1113-1) - UPC - TS - -- - 34/89 -  - 34/89 - DIS