| Chinese yam has a long history of cultivation in my country.It has a wide planting range and large planting area.Its medicinal value and nutritional value are high.It is a "medicine and food homologous" crop with good market prospects and industrial development potential.At present,the traditional methods of yam harvesting are mostly manual excavation and mechanical side ditching to assist manual harvesting.There are a series of prominent problems such as high labor intensity,low operation efficiency,high harvesting cost and low harvesting integrity rate.This greatly reduces the economic benefits of yam growers,seriously affects the enthusiasm for planting,and is a key problem restricting the development of the yam industry.The yam harvester can complete the functions of ditching and breaking the soil,vibrating the soil and separating the vegetable soil at one time,so that some tubers of the underground yam are exposed,and the harvest of the yam can be completed by manual extraction,which is labor-saving and efficient.However,the existing yam harvester still has the problems that the yam is easily damaged during the harvesting process,the applicability between the machine and the soil is poor,and the construction cost is high,which affects the reliability and economy of the machine.Therefore,it is of great significance to develop and design a yam harvester with a relatively high harvesting integrity rate to improve the level of mechanized harvesting of yam and promote the development of the yam industry.Based on the above analysis,the main research contents of this paper are as follows:(1)Combined with the agronomic requirements of yam planting and harvesting and the shortcomings of the existing harvesters,the complete machine plan of the hanging yam harvester was determined.The developed machine mainly includes suspension device,harvester frame,trenching and soil breaking device,soil dumping and backfilling device,vibration excavation soil breaking device,transmission system and real-time online monitoring system.The harvester can simultaneously realize the functions of ground breaking,ditching,lifting and dumping,soil backfilling and separation of yam tubers and soil,and can display the operating parameters of the harvester in real time,effectively improving the convenience and safety of the harvester operation.(2)The structure design and main parameters are determined for the ditching and soil breaking device,soil dumping and backfilling device,vibration excavation soil breaking device and suspension device of the whole machine,and the overall model is built by using the three-dimensional drawing software Solid Works.Using the Motion and Simulation plug-ins of Solid Works comprehensively,under extreme conditions,the structural static analysis and dynamic analysis of the chain cutter in the trenching earth breaking device and the grid-type vibrating shovel in the vibration excavation earth breaking device were carried out respectively to verify and analyze Reliability of critical components.(3)Based on the discrete element method,the numerical simulation of the operation of the vibrating soil crushing device was carried out,and the soil crushing process,the fracture of the bond bonds between soil particles and the force of the yam in the virtual simulation were analyzed.Taking the operating parameters that affect the soil crushing effect as the influencing factors,and the number of bonding bonds in the area and the force of the yam as the evaluation indicators,single-factor and multi-factor experimental analysis was carried out.The order of the significant degree of influence of each factor on the remaining number of bond bonds in the area is determined as follows: vibration amplitude > vibration frequency > machine travel speed > initial inclination angle of the vibrating shovel.The order of the significant degree of influence of each factor on the force of yam is: initial inclination angle of the vibrating shovel>vibration amplitude>vibration frequency>machine traveling speed.(4)According to the design plan of the hanging yam harvester,the processing and manufacturing of the whole machine prototype was completed,and a series of field tests were carried out.Based on the analysis of the discrete element virtual simulation test,with the help of Design-Expert software,the crankshaft speed,the traveling speed of the machine tool and the inclination angle of the vibrating shovel are selected as the influencing factors,and the three-factor and three-level test is carried out.Analyze the influence of various factors on the harvest integrity rate in actual operation and carry out optimal design and analysis.The results show that the optimal parameter combination for the maximum harvest intact rate is the crankshaft speed of306.18r·min-1,the travel speed of the machine tool of 137.85m·h-1,and the initial inclination angle of the vibrating shovel-6.18°.The parameters were tested and verified,the yam harvesting integrity rate was 90.855%,and the operational performance of the optimized yam harvester was significantly improved. |
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