Sugarcane is an important crop for South Africa. It provides employment and valuable foreign / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2007

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A whole-stalk harvester was developed as part of a sweet sorghum-for-ethanol production system. Gathering chains grasped the stalks as they were cut at the base with a disk-cutter. These stalks were flipped onto a cross conveyor and deposited into an accumulator. Periodically the machine stopped and the accumulator was dumped. All the components on the harvester are powered hydraulically. Five pumps on the harvester supply flow to seven actuator circuits. Power is delivered to the pumps from the tractor PTO via a universal joint driveline. Each of the six existing circuits and one proposed circuit were modeled with bond graphs and implemented for computer analysis using TUTSIM. Model validation was done by comparing simulated and measured driveline torque, line pressure, and return line flow rate in each of the six existing circuits. Data collected on the gathering chains circuit was used to analyze the effect of driveline joint angles on transmitted torque and pump output. Torque measurements at three driveline angles showed a torsional vibration with a primary harmonic at driveline rpm and a secondary at twice driveline rpm. A combination of Cardan joint characteristics, mass unbalance, the secondary couple, and non-linear driveline and V-belt stiffness was used to model the driveline. Resulting simulated torque emulated the experimental very well. Measured pressure in the gathering chains circuit showed relatively low fluctuations at the highest amplitude torsional vibration (highest driveline joint angles). It was concluded that driveline vibration would not significantly affect the gathering chains circuit performance. The cross-conveyor motor circuit simulation showed close agreement to experimental results. Mean predicted flow, pressure, and torque were within 8.9, 7.3, and 7.7 percent of mean measured values. A simulation with a stalk load on the conveyor showed that power requirement increased only 8.0 percent. The accumulator dump circuit was analyzed to determine if the load on the motor would become over-running and cavitate the pump or motor as the stalks were being dumped. Simulation showed that a bundle up to 300 kg could be dumped without over-running the motor, and since this was a larger bundle than the bin could hold, a design modification was not necessary. The disk-cutter circuit was designed based on simulation results for several combinations of motor, pump, and sheave ratio. A 7.3 cm³/rad motor, 2.53 cm³/rad pump , and 2:1 sheave ratio produced the correct disk-cutter speed, and low torsional vibration when cutting the stalks, consequently this combination was selected for the design. / Ph. D.

Orientador: João Eduardo Guarnetti dos Santos / Banca: Luis Carlos Paschoarelli / Banca: Cristiane de Affonso Almeida Zerbetto / Banca: José Carlos Plácido da Silva / Banca: Jair Rosas / Resumo: A colheita mecanizada de cana-de-açúcar se expande consideravelmente, principalmente em São Paulo, o principal estado produtor. Como a maioria dos produtos industrializados modernos há um grande compartilhamento de sistemas, visando a redução dos custos de desenvolvimento e fabricação. As vantagens econômicas deste compartilhamento não têm apresentado a mesma eficácia quando tratamos da ergonomia na interface "homem x máquina". A usabilidade de um produto tem influencia de diversos fatores regionais atuando diretamente seu grau de adequação às necessidades dos usuários. Uma das prerrogativas do design ergonômico como atividade projetual é a compreensão da interação entre o usuário e seu produto. Para tanto foram avaliadas dois modelos contemporâneos comercializados pelas principais empresas no ramo. Foram coletados dados coletados sobre a disposição espacial dos comandos, acesso ao posto do trabalhador, nível de exposição ao ruído e satisfação ponderada dos trabalhadores sobre diversos aspectos do equipamento. Os dados obtidos foram comparados com as normas e a literatura e com as informações indicadas pelos usuários. Este trabalho apresenta o nível de eficiência destes equipamentos quando utilizados nas lavouras paulistas buscando fornecer subsídios para o desenvolvimento destes equipamentos e fomentar novas pesquisas para a melhor adequação ao trabalhador / Abstract: Mechanized harvesting of sugarcane has significantly, especially in Sao Paulo, the most important producing state in Brazil. As almost moderns industrial products this equipments share many sustems, aiming the costs reducing in development and manufacturing. The economic advantages of sharing systems may not have the same efficiency in ergonomics of "man x machine" interface. The usability of any product is influenced by many regional factors that influence directly their degree adjustment of the user's needs. One of ergnonomic design prerogatives is to understand the interaction between the user and your product. So, we have evaluated two contemporary models of the major companies in the Brazilian market. We collected data about the control's spatial layout operation's cabin acess, noise exposure level and worker's satisfaction about many aspects of the equipment. Making a comparison between the data obtained, the standards, the literature and the information given by users, we looked for any relationship shows ergonomics problems. This paper presents the ergonomic efficiency level of these devices in Sao Paulo's state farms trying to provide subsidies for these equipments development and stimulating further research to adapt these machine to the worker's need / Mestre

Thesis (MScFor)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Made available in DSpace on 2014-06-11T19:24:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-22Bitstream added on 2014-06-13T18:20:19Z : No. of bitstreams: 1 correa_ja_me_bauru.pdf: 4329757 bytes, checksum: 78c2c65932678dc466b7754ca89b10e3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A colheita mecanizada de cana-de-açúcar se expande consideravelmente, principalmente em São Paulo, o principal estado produtor. Como a maioria dos produtos industrializados modernos há um grande compartilhamento de sistemas, visando a redução dos custos de desenvolvimento e fabricação. As vantagens econômicas deste compartilhamento não têm apresentado a mesma eficácia quando tratamos da ergonomia na interface homem x máquina. A usabilidade de um produto tem influencia de diversos fatores regionais atuando diretamente seu grau de adequação às necessidades dos usuários. Uma das prerrogativas do design ergonômico como atividade projetual é a compreensão da interação entre o usuário e seu produto. Para tanto foram avaliadas dois modelos contemporâneos comercializados pelas principais empresas no ramo. Foram coletados dados coletados sobre a disposição espacial dos comandos, acesso ao posto do trabalhador, nível de exposição ao ruído e satisfação ponderada dos trabalhadores sobre diversos aspectos do equipamento. Os dados obtidos foram comparados com as normas e a literatura e com as informações indicadas pelos usuários. Este trabalho apresenta o nível de eficiência destes equipamentos quando utilizados nas lavouras paulistas buscando fornecer subsídios para o desenvolvimento destes equipamentos e fomentar novas pesquisas para a melhor adequação ao trabalhador / Mechanized harvesting of sugarcane has significantly, especially in Sao Paulo, the most important producing state in Brazil. As almost moderns industrial products this equipments share many sustems, aiming the costs reducing in development and manufacturing. The economic advantages of sharing systems may not have the same efficiency in ergonomics of man x machine interface. The usability of any product is influenced by many regional factors that influence directly their degree adjustment of the user's needs. One of ergnonomic design prerogatives is to understand the interaction between the user and your product. So, we have evaluated two contemporary models of the major companies in the Brazilian market. We collected data about the control's spatial layout operation's cabin acess, noise exposure level and worker's satisfaction about many aspects of the equipment. Making a comparison between the data obtained, the standards, the literature and the information given by users, we looked for any relationship shows ergonomics problems. This paper presents the ergonomic efficiency level of these devices in Sao Paulo's state farms trying to provide subsidies for these equipments development and stimulating further research to adapt these machine to the worker's need