Design and operating parameter optimization of comb brush vibratory harvesting device for wolfberry
【Abstract】Wolfberry (Lycium barbarum) is a plant of Solanaceae. Studies have shown that the LBP has many effects, such as delaying aging, anti-tumor, anti-fatigue, controlling blood sugar, and preventing glaucoma. The main producing areas of wolfberry are Ningxia, Inner Mongolia, Xinjiang, Hebei, Qinghai, Hubei, and Tibet. In recent years, wolfberry area has been increasing by 11% annually. Wolfberry has indefinite inflorescence, and the end of June to early October is the picking period of wolfberry. Wolfberry is in continuous flowering during the picking period, and the average picking cycle is seven days. Wolfberry picking is still artificially, so low efficiency and high labor cost are the most prominent issues. The efficiency of artificial picking wolfberry is only 3–5 kg/h, while the cost is up to CNY 34 500 per hectare, accounting for more than 50% of production cost. With the growing area of wolfberry, the labor force will be in short supply, so the picking problem has become the bottleneck restricting the sustainable development of wolfberry industry. Wolfberry is less cultivated abroad, so there are few studies on large-scale cultivation and mechanized picking of wolfberry in foreign countries. The research on wolfberry picking machinery in China began in the early 21st century and was carried out mainly in several major producing areas. At present, according to the different principles of picking, wolfberry picking machinery can be divided into four main types: shear, brush comb, vibration, and air flow. However, the current various picking machinery has obvious defects. In this study, we designed a vibrating wolfberry harvesting device with comb brush bases and tested its performance. The device consists of harvesting unit and lifting mobile unit. The harvesting unit includes comb brush vibration mechanism, DC motor, timing pulley, support frame, and baffle. Among them, the comb brush vibration mechanism is the key component, which including left input shaft, right input shaft, harvest rod, T reducer, disc, connecting rob, coupling, slider, and sliding shell. The four rows of harvesting poles and the shell are fixed by bolts. The shell and the slide are also fixed by bolts. The slide rail and the slider are matched with each other so as to make linear motion along the slider. The two ends of the connecting rod are respectively hinged with the shell and the disc. The harvesting unit is used to achieve the recovery of wolfberry fruit. Lifting mobile unit is a hydraulic lift trolley. The harvesting unit is fixed on the lifting mobile unit, and the whole harvesting device can move horizontally and vertically. Based on ADAMS software, the model of L. barbarum fruit and branch, the model of comb vibration are established by parameterized modeling. The connecting force between fruit and fruit stem is connected by the generalized force. The sensor is used to monitor the fruit stem breakage condition, which realizes the process control of separation of wolfberry fruit and stem. Through the simulation analysis, it is determined that the brushing speed, the disc speed (vibration frequency) and the vibration amplitude of the harvesting device have significant effects on the shedding of wolfberry fruit. The field experiment was carried out to evaluate the harvest efficiency, the harvest rate of mature fruits, the shedding rate of immature and the damage rate of mature fruits. The test results showed that the best combination was that the comb brush speed at 80 r/min, disc rotation speed at 100 r/min, and vibration amplitude at 80 mm. Based on the combination of the factor level, the harvest efficiency was 13.12 kg/h, the harvest rate of mature fruits was 87.46%, the shedding rate of immature fruits was 13.81%, and the damage rate of mature fruits was 2.82%. Compared with other single-principle harvest mechanisms, the device not only achieves harvest efficiency and higher mature harvest rate, but also guarantees relatively low shedding rate of immature fruits and damage rate of mature fruits. This study can provide a theoretical basis and data support for the design of the mechanized harvesting machinery of wolfberry.
【Keywords】 agricultural machinery; harvesting; vibrations; wolfberry; comb brush; optimization;
(Translated by LIU T)
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