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Design of a Shaker-Clamp System for Inertial Shaker of Coffee Trees

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  031143,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.13747) @2003
Authors:   Federico García-Uribe, Carlos Eugenio Oliveros-Tascón
Keywords:   Coffee (Coffea arabica), mechanical harvest, inertial trunk shakers, shaker-clamp system mechanical damage, transmission of vibrations

The trunk shaking is a promising alternative for the selective mechanical harvesting of coffee. In studies carried out in Cenicaf, was observed that it is possible to detach more than 60% of ripe coffee berries with less than 10% immature coffee berries in the harvested mass in less than 15 s, represents 6,3% of the time required by a picker in the traditional manual harvesting. In those studies it was also observed that mechanical damage in the coffee bark, in the shaker-clamp zone, in the majority of the shaking trees could facilitate the entrance of diseases such as Ceratocystis fimbriata fungus which causes the trees death a high percentage of the time. This research has generated the necessary information for the design and operation of trunk shaker-clamp systems to efficiently transmit the vibration yet avoids the mechanical damage in the bark of the coffee tree. The research was divided into two parts. In the first, in the laboratory, the admissible radial stress [ sR Adm. ] of the coffee bark for three ages of trees (48, 60 and 72 months), using a universal machine (INSTRON 5569 .) for controlled deformation and by means of histology studies (at the tissue level) was determined. The second part, the shaker-clamp system evaluation, consisted of: the measurement of the vibration transmission in the shaker-clamp system using accelerometers, hardware and software to collect and process the vibration signals, evaluation of the visible mechanical damage and at tissue level in normal conditions of operation of the shaker. For it was used films developed to measure the contact pressure between two contact surfaces in order to know the pressure distribution and their magnitude in the shaker-clamp zone. The obtained results, for the shaker-clamp system show that the radial admissible stress [ sR adm ] for the ages of trees considered was 2068,2 kPa (300 psi), the visible mechanical damage and at tissues level was 0% and the transmission of the vibration with the shaker-clamp system developed was higher than 80%.

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