Analysis and experiments of reciprocating cutting parameters for apple tree branches

Abstract: With the continuous expansion of modern orchard planting scale, mechanical pruning is widely used in fruit production, and the basis of pruning equipments development is to determine the cutting performance parameters of branches. In order to explore the shearing mechanical properties of apple branches, find the optimal cutting parameters, and support the development of subsequent pruning equipment, based on a self-made reciprocating branch cutting test bench, the influences of branch diameter, average cutting speed, cutting gap and sliding cutting angle on the peak cutting force of apple branches were explored through single factor experiment. The cutting test bench included a cutting bench, a branch feeding system and a measurement control system. The breed of the branches used in the experiments was Fuji, and the branches were free of disease and insect pests. The branches selected for the tests were straigh, with a diameter range of 8-35 mm, moisture content was from 38.7% to 66.2%. In single factor experiment, the branch diameter was from 10 to 27 mm, the range of average cutting speed was 0.1-0.45 m/s, and 8 levels was set for both factors. The cutting gap ranged from 0.1 to 2.0 mm with 6 levels. The sliding cutting angle was 10°, 15° and 20°. Three repetition was conducted at each level. The results demonstrated that the peak cutting force increased linearly with the branch diameter, but decreased when the average cutting speed and sliding cutting angle were increasing. With the enlargement of the cutting gap, the peak cutting force decreased first and then increased. The cutting section became smoother with the increase of the average cutting speed, while the cutting gap had little effects on the quality of the cutting section. Based on the results of single factor experiments, multiple factor experiments were conducted with the average cutting speed, cutting gap and sliding cutting angle as influence factors, and the peak cutting force as the responsive variable. The regression model was established. The optimization analysis results showed that under the test conditions, the optimal cutting parameter combination for apple branches with the average cutting speed of 0.4 m/s, the cutting gap of 1.5 mm, and the sliding cutting angle of 20°, based on this the theoretical peak cutting force was 560.97 N, the deviation between which and the average measured value of the peak cutting force was less than 4%, the optimization model was reliable. This study could provide design data support for the development of apple branch pruning equipment in future.