Design And Research Of Mechanical Blossom Thinning Device For The Dwarf Dense Fruit Trees

Blossom thinning is one of the most arduous operation steps in orchard production management.Mechanized thinning is a new technique for raising the efficiency and reducing the cost in large-scale,dwarf-dense orchard cultivation.This paper analyzed the flower breaking mechanism and the mechanism of blossom thinning of different flower bud types of apple and peach according to the cultivation pattern of the apple cultivation model and the agronomic requirements of the trunk or dense planting peach tree orchard,and selected the material brushing components and the thinning method.Inventor software was used to establish three kinds of design models,namely the straight-through model,skew-in model,and spindle-type model.By comparing and analyzing the working principle of different models and the stress of flowers,the spindle-type blossom thinning model,as the optimal structure form,was selected based on the principle of lighter operation.The blossom thinning axis components of the spindle-type thinning device were designed and analyzed,and a three-dimensional model of the thinning shaft was established.The diameter of the thinning shaft was checked and the reference ideal diameter of the shaft was Φ49.4 mm.The diameter of the standard series of hollow shafts Φ48 mm was selected as the blossom thinning axis.Different thickness models of the thinning shafts were established.The resonance frequencies were calculated and the first-order modal frequency data of the blossom thinning shafts were compared.When the wall thickness was 6.5 mm,The vibration frequency is the largest,and the first-order vibration frequency of the shaft was 120.6 Hz,and the maximum displacement was 75.08 mm.The trajectory was obtained from the kinematics simulation of the thinning-axis parts,consistent with the kinematic analysis trajectory.Trial thinning device was made.Different brushing parts of different materials were installed on the thinning shafts according to different densities and different lengths.Field experiments were conducted on dwarf-dense apples and trunk-type dense-planted peach trees respectively.Peach field experiments showed that the effect of blossom thinning was obvious when the rotating speed of the thinning shafts was in the range of 350 r/min to 370 r/min.Six types of brushing parts with different densities,length and materials were selected in the experiment to compare the results.Under the designated combination of brushing parts,thethinning effect meets 30% to 50% of the blossom thinning rate,and maintains a good thinning uniformity.The ratio of the thinning rate over 50% to the total number of the test buds does not exceed 30%.Compared with the artificial blossom thinning in the orchard,the efficiency of mechanical thinning increased by 10 times.Experiments in dwarf-dense apple orchard showed that when the rotating speed was in the range of 350 r/min to 370 r/min,the effect of thinning on the upper part of the branches was not obvious.When the rotating speed reached450 r/min,the blossom thinning device would remove most apple flowers and leaves.