Design and test of banana skewer fruit holding mechanism

Objective  Banana harvesters are equipped to carry large loads of bunches. We propose a nail holding mechanism for bananas which posses high strength and reliable clamping force while ensuring flexible and effective operation.

Method  An inner palm holding mechanism with nails for picking bananas was designed, the clamping effects of different combination factors affecting the gripping force were tested, and the clamping test platform was built. The three main factors of cylinder pressure, the number and arrangement of nails affecting the clamping effect were selected, and the single factor experiment and response surface method were used to test the clamping force.

Result  In the cylinder pressure test, when the cylinder pressure was 0.4 MPa, the corresponding tension was about 500 N closest to the maximum static friction force between the banana handle and the palm, and banana could be clamped stably. In the test of nail arrangement, the friction that the rectangle could withstand was the maximum with a value of 800 N, which was greater than the maximum static friction force between the banana handle and the palm, and the stable clamping effect could be obtained. In the test of nail number, when the numbers of nails were eight and ten, their pulls closed to. The reason may be that the banana handle is not a regular cylindrical shape, so that the nails on the round holding palm may not be all inserted into the banana handle. When the number of nails was eight or ten, only six nails plunged into banana handle and effectively clamped. When the number of nails exceeded ten, the tension dropped instead of rising. The reason for this phenomenon may be that the more nails there are, the more serious the mutual interference occurs, and the number of effective nails decreases instead of rising.

Conclusion  The factors influencing the clamping force effect of clamping mechanism are cylinder pressure > nail arrangement > number of nails. The optimal parameter combination is 0.4 MPa cylinder pressure, ten nails and rectangular arrangement. This paper provides a theoretical reference for the design of clamping mechanism of key components of banana harvester equipment in flat banana plantation.