Investigations on design parameters for the development of a pineapple harvester

Abstract

The pineapple (Ananas comosus) is a tropical fruit with significant economical importance. The mechanisation in the field of pineapple harvesting has become inevitable. Basic information on its cultivation practices and physical and mechanical properties is essential for the design and development of suitable machinery. Cutting energy and cutting force requirement are some of the vital information in the design aspects of mechanical harvester. As brush cutters have become very common machinery used by farmers and different attachments on brush cutter suitable for harvesting paddy, sugarcane and pineapple have already been developed and are used. Hence, this study is focused on investigation on design parameters for the development of a pineapple harvesting attachment to brush cutter and evaluation of different designs of fruit holders. The cutting energy requirement was determined using an impact test rig apparatus. The maximum cutting force was then calculated from the cutting energy. For the mechanical harvesting of pineapple, three fruit holders were designed and fabricated. The holder-A supports the fruit and the distance between the cutting edge and holder is fixed. Holder-1 supports the fruit and it can move with respect to the cutting edge. Holder-2 can grip the fruit but the distance and between the cutting edge and holder is fixed. Holder-3 can grip the fruit and it can move with respect to the cutting edge. The field tests of the holders were then conducted to evaluate their performance in comparison with the existing fruit holder. The average height of a pineapple plant was obtained as 94.57 cm with a standard deviation of 20.62 cm. The average number of leaves was obtained as 47 with a standard deviation 13.2. The average height of fruit from groundand angle of inclination was observed as 33.2 cm and 38.2o respectively. The average diameter of stem was 26.69 mm with a standard deviation of 8.57 mm. The maximum cutting energy and force of pineapple stem was obtained as 18.10 J and 842.70 N respectively, during the first harvest. In case of pineapple leaves, older leaves require maximum cutting energy of 9.60 J. The field evaluation of fruit holders was conducted and it was found that the holder-1 with 150 mm diameter blade requires minimum time for harvesting, 132 fruits/ h, minimum damages of leaves, 5 nos. and more comfortable in handling and operating.