Design and experiment of self-propelled cotton topping and directional spraying machine

Abstract: At present, the operation quality of China's cotton spraying machinery is low, such as low efficiency, poor utilization of pesticides, serious environmental pollution and other outstanding issues. To reduce pesticide losses and improve utilization of pesticides, protect the environment and improve economic benefit, one self-propelled cotton multi-topping spraying machine with high clearance universal chassis was developed. It integrated the high ground clearance universal chassis, a hydraulic control system, an air supply system, a multi-topping device and a directional spraying device. And their key device parameters were calculated. The general chassis length, width and height were 3 100, 2 900 and 1 870 mm, respectively, the minimum ground clearance was 1 000 mm, the maximum power was 35 kW, the container capacity was 600 L, the drug pump flow was 0-80 L/min, the fan air volume was 9 850 m3/h and the normal forward speed of the machine was 1-5 km/h. The multi-topping and spraying efficiency of the machine were 1.09-1.52 and 1.64-2.28 hm2/h respectively when the machine was working normally. According to the actual need of work pressure, the working pressure of hydraulic motor was selected as 20 MPa. In order to adapt to different height of the cotton, the height of the multi-topping device could be adjusted. The number of rows for the multi-topping and spraying was respectively 4 and 6 lines. After the cutting speed test, the cutting speed should not be less than 500 r/min so that the cotton top branches were completely cut. According to the substitution principle, the theoretical air flow of the centrifugal fan was at least 9 850 Pa, and meanwhile the shaft power of the centrifugal fan was 5.6 kW. For the height of cotton in different growth stages, the relative height of directional spraying device was controlled by hydraulic system, the duckbill outlet was fixed in the u-shaped circular slider by u-shaped slide block, and the nozzle was fixed on the duckbill outlet. The adjustment range of the spraying nozzle was 0-30°, and when the nozzle angle was 20°, the droplet diameter and the distribution uniformity effect were the best. In the self-propelled cotton multi-topping spraying machine, this innovative design of disassembly type multi-topping spraying device could greatly reduce the cost. Multi-topping experiment showed that the mechanical multi-topping rate was 7-8 times of the artificial topping rate, and the leakage rate of topping for 100-plant was 30% higher than the artificial topping. For the directional spraying, the deposit volume of the sent droplets under the windy condition was increased by 60.38% compared to that when there was no wind, the variation coefficient was reduced by 25.64%, and the penetrating effect of sending droplets by wind was obvious. The prototype's droplet deposition performance and directional spraying performance are good, which improve the utilization rate of pesticides. The presented study provides a approach for the cotton topping and the protection of cotton spraying.