Effects of Frequency and Mass of Eccentric Balls on Picking Force of The Coffee Fruit for The As-Fabricated Harvesting Machines

Abstract

Currently, Vietnam ranks second about the coffee export in the world. To match that position, the use of coffee harvesting tools/machines according to the automatic trend is essential. However, the most common forms of coffee harvesting in Vietnam are manual, improved manual-coffee picking machines that are imported from foreign countries. The above harvesting forms have low productivity and have some disadvantages such as labor cost, labor hiring, high labor cost, and long harvesting time, low harvesting, and post-harvesting quality. Studies of scientists around the world have applied the principle of vibration to produce the picking force for coffee fruits, and the picking force is known to be different from many factors in every region of the world growing coffee. The paper presents the method of design and manufacturing an automatic coffee harvesting machine based on the evaluation of picking force for coffee in Vietnam. The influences of eccentric ball mass and vibrating frequency on the magnitude of the picking force are carefully calculated. On that basis, the experimental programming is applied to find the optimal working point of the picking machine for coffee. The results showed that the eccentric ball mass of 8.5 kg, the rotation speed of the eccentric ball from 480 to 574 rpm would produce the picking force by the coffee fruit of Vietnam.