| Water chesternut(Eleocharis dulcis),is a very common characteristic aquatic vegetable in the south of China.It is usually eaten with underground expanded bulbs.Its fruit has high nutritional value and has both edible and medicinal effects.After processing,it can be used to make preserves,cans,etc.which can create high economic value.Water chestnut is a kind of crop with easy planting and high yield,but its fruit is buried underground,which leads to great difficulty in harvesting.In all links of water chestnut planting,water chestnut harvesting is the most difficult.The labor force invested in the harvesting process accounts for more than 70% of the labor force required in the whole production process,which leads to harvesting becoming a bottleneck link in the production process of water chestnut and limits the development of water chestnut industry.In this paper,combined with the performance requirements of water chestnut mechanized harvesting on harvesting machinery,a mechanically disturbed water chestnut mechanized harvesting technology applied to harvesting with water is proposed,and a trawler-type water chestnut harvester in paddy field was developed.To solve the problem that it is difficult to separate the water chestnut fruit from the soil in the harvest process,an excavation and harvest mechanism composed of three-stage disturbance roller and lifting separation shovel is designed.In view of the muddy field environment and difficult steering of machinery after soaking the field,a special crawler chassis driven by hydraulic system is designed,and the field performance test was completed.The main research contents are as follows:(1)The overall structure design of trawler-type water chestnut harvester in paddy is completed.According to the agronomic requirements of water chestnut harvest,a structural scheme of trawler-type water chestnut harvester composed of crawler chassis,rotating disturbance device,lifting and separation device,collection device and power and transmission system was analyzed and determined.The working width is 800 mm,chassis gauge is 1320 mm,track grounding length is 1600 mm,track width is 180 mm,and the design driving speed is 0.8 m/s.(2)The structural design optimization and strength check of the chassis frame were carried out.According to the structural layout of the machine,the frame design and static analysis is completed.The results show that there is excessive redundancy in the structural design of the frame,and its structure needs to be optimized.The thickness of the frame material is reduced and some reinforced structures are deleted.After optimization,the maximum strain of the frame is 0.50 mm,the deformation is reasonable,and the maximum stress is 122.97 MPa,which is less than the yield strength of the material.The strength of the optimized frame structure meets the design requirements,the weight of the frame is reduced by 58 kg compared with that before optimization,and the weight reduction effect is obvious.(3)A digging and harvesting mechanism matched with trawler-type water chestnut harvester is designed.The mechanism mainly includes rotating disturbance device,lifting separation device,sub frame for placing various working parts and mechanical transmission system.It can fully mix water chestnut fruit,soil and water,so that the soil moisture content reaches supersaturation and the mixture presents a flowing state.The lifting separation shovel scoops up the mixture and separates the fruit and muddy water to realize the harvest of water chestnut fruit.According to the size of water chestnut fruit,the key structural dimensions of disturbance roller and lifting separation shovel are designed to ensure that the components can realize the design function.(4)The performance analysis of the crawler chassis is carried out.Through analysis and calculation,the minimum steering radius of differential steering of the crawler chassis is 1543.50 mm,and the steering radius of in-situ steering is 1037.11 mm.The steering performance of the crawler chassis is excellent.The longitudinal up and down slope limit overturning angles of the crawler chassis are 55.63 ° and 55.08 ° respectively,the limit overturning angle is large,and the chassis is stable.The maximum vertical obstacle crossing height of the crawler chassis is 245.30 mm and the maximum ditch crossing width is 791.67 mm.The trafficability of the prototype is strong.(5)The design of crawler chassis hydraulic drive system is completed.According to the three typical working conditions of trawler-type water chestnut harvester,the traction force required by the hydraulic drive system is checked,and the selection of key components such as walking motor and hydraulic pump of the hydraulic drive system is completed.The selection of auxiliary components such as directional valve,oil pipe,oil tank and radiator is further determined,and the design of crawler chassis hydraulic drive system is completed.(6)The chassis performance test and field harvest test of trawler-type water chestnut harvester were carried out.The results is that the maximum driving speed is 0.97 m/s,the average straight deviation rate is 4.43%,the minimum steering radius of differential steering is 2.1 m,the steering radius of in-situ steering is 1.3 m,and the maximum climbing angle is 24.2°.The chassis performance is excellent.The digging rate,loss rate and damage rate of the prototype are 53.19%,46.81% and 4.21% respectively.Due to the influence of test conditions,means and environment,the loss rate of the prototype is high,which needs further research. |
PDF Full Text Request