Abstract:
Two-stage peanut harvesting is one of the most popular mechanized ways in China. Among them, the commonly used pickup device can be equipped with the spring teeth cylinder in large and medium-sized picking and harvesting machines. There are some challenges, including plant throwing, stacking, missing picking, and fruit falling damage. At the same time, the spring teeth can circularly scratch into and out of the ground during the operation of the pickup device, leading to dust. The efficiency of peanut picking and harvesting can be seriously restricted to increase the loss of pods falling during harvesting. The action of the pickup time on the ground has also exacerbated the dust pollution. This study aims to combine the structure of the toothed drum mechanism in the new type of pickup device with the shovel teeth and double-cylinders for bunch upright peanuts. According to the upright peanut plant shape, strip laying, motion posture and dynamics during picking, the peanut pickup device consisted of shovel teeth, a pushing cylinder, and a picking cylinder (referred to as a double cylinder). The better performance of picking peanuts was achieved in the sequential coordination with four beats of shovel pluck pick delivery. The traditional single-toothed drum pickup device was replaced in this case. The shovel tooth structure of the circular arc working surface was designed to determine the range of shovel tooth radius using geometric relationships. The structure of pushing teeth and picking teeth was designed with a backward inclination angle. The structure and rotation radius of two rollers were determined to design the semi-enclosed protective plate structure with the specific parameters. The motion parameters of the unit were obtained to simulate the range of picking speed ratio after ADAMS simulation. A prototype of a combined peanut pickup device was conducted to develop the shovel teeth, picking cylinder, pushing cylinder, and half guard board in field performance tests. According to Box Behnken central combination design, an orthogonal experiment was conducted on the peanut plant picking rate and peanut pod drop rate as experimental indicators, while the unit forward speed, picking speed ratio, and shovel teeth radius as experimental factors. The test results indicate that the shovel teeth double cylinder combined peanut pickup device operated smoothly, where there were no plant throwing, pile up, and dust from bullet teeth during peanut picking; The mean value of picking rate of peanut plant was 99.22%, and the mean value of pod loss rate was 1.84%, when the forward speed was 1.2 m/s, the picking speed ratio was 1.2, and the shovel teeth radius was 498 mm under field experimental conditions. The findings fully met the requirements for peanut picking.