Efeito da utilização de frequências de vibração na faixa de 35 a 55 Hz sobre a eficiência de derriça do café

• Ano de defesa: 2011
• Autor(a) principal: Guedes, Denis Medina
• Orientador(a): Queiroz, Daniel Marçal de
• Banca de defesa: Khoury Junior, Joseph Kalil
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Engenharia Agrícola
• Departamento: Construções rurais e ambiência; Energia na agricultura; Mecanização agrícola; Processamento de produ
• País: BR
• Palavras-chave em Português: Café; Colheita mecanizada; Derriça; Vibração
• Palavras-chave em Inglês: Coffee; Mechanized harvesting; Fruit; Vibration
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/3596

Harvesting is one of the most costly operations in coffee production. This operation presents several problems to be performed. Coffee harvest machinery usually detaches the fruits by mechanical vibration and impact. The study of the behavior of the fruit stalk and branch system under different frequencies and amplitudes of vibration has fundamental importance for the design of coffee harvest machinery. This work aimed to evaluate the effect of vibration frequencies higher than 25 Hz associated with amplitudes lower than 7 mm in the selective and total detachment efficiency of the coffee fruits. Experimental tests were conducted in an oscillating electromagnetic machine to determine the effect of various factors related to the detachment efficiency of the coffee fruits. The factors were: the frequency (35, 40, 45, 50 and 55Hz), amplitude (3.5, 5.0 and 6.5 mm), length of primary branches (5 and 10 cm), ripeness degree of the fruit (green and ripe) and harvest time (middle and late). Two experiments were performed with fruits of Catuaí Vermelho: The first in order to evaluate the effect of different branch lengths, frequencies and amplitudes of vibration on the detachment efficiency, total and selective, of the coffee fruits in arrangements containing different fruit ripeness degrees; and the second one, to evaluate the effect of these factors: branch length, frequency and amplitude of vibration on the detachment efficiency of the coffee fruits on branches containing ripe and green fruits separately. From the statistical analysis, regression models were developed to describe the detachment efficiency in each of the conditions studied. From the experimental results, it was concluded that detachment efficiency of coffee in the middle of the season showed no statistically significant difference between the ripe and green ripeness degrees. By the end of the harvest, the ripeness degree was significant for the detachment efficiency values, indicating the influence of the harvest period in the selectivity of the detachment by vibration. It was found that the detachment efficiency of coffee fruits is directly related to the frequency and amplitude of vibration. In the 5-cm branches, the detachment efficiency is more sensitive to variation, compared to the 10-cm lenght branches, varying the frequencies and amplitudes of vibration. The maximum values of detachment efficiency estimated by the models show that in the evaluated range of frequency and amplitude, the detachment efficiency of green fruits would be higher than the ripe ones. For the levels evaluated, the total harvest of coffee fruits by vibration could be an unfeasible alternative because it does not reach detachment efficiency values higher than 50% in a single pass.