| Rice is one of the most important food crops in China.But its planting mechanization level is low at presnet,which seriously restricts the development of mechanization inrice production.Rice hill-drop technology is a cultivation technique that can spread seeds into points orderly.Because this technique can cultivate the yield of rice without the process of sprout cultivation,moving and transplanting,it has the advantagies of cost-saving and yield-increasing.Based on the production needs and market demands,the present study has desiged a lightsimplified rice precision rice hill-drop machine,and the following works have been carried out:(1)The technical requirements of hill-drop and the overall design of the lightsimplified of rice precision spot hill-drop machine were introduced.The prototype test was carried out in Chongming Island.The results showed that: a)For the rice variaties of hybride rice of superior flower 14,the average number of seeds in each small cell was 3～4,the coefficient of variation of the grain was about 30%.b)For the rice variaties of of conventional rice of south terrier 46,the average number of seeds in each cellwas 11～12,and the coefficient of variation was 25%.The coefficient of variation between rows was less than 10%,and the emergence rate was 60～80%.The amount of seeding rates in the field was slightly smaller than that of the bench test,the malfunction of the prototype was analysed,and the prototype was further optimized.(2)The plastic seed metering device for the hill-drop machine was optimizedmainly from four aspects: seed cell,filling room,seed belt and material.The cell wheel has small,medium and large size types,with the ladle shape,and the number of cells is 8.The long axis of the cell is 16～18 mm,the maximum depth is 9.98 mm,the inclination angle of the filling chamber is 60°,the rice seed has good fluidity,and the unloading plate is equipped for easy unloading.The belt has good elasticity and has a service life of more than 300 hours.The cleaning mechanism uses flexible bristles to effectively clean the excess holes on the surface of the cell.The material of the seed meter is mainly nylon and ABS.The space of the filling chamber has been enlargeed to store more rice species,and the seeding plate is arranged below the filling chamber to facilitate unloading.The protective tape is made of nitrile rubber with better wear resistance and fit,which reduces the deformation of the seed belt and improves the service life.(3)The bench test was carried out by using four factors of variety,seed rotation speed,cell size and plate limit position to form 8×4×3×2 of factors and levels test.The results of range analysis showed that the factors affecting the sowing amount were cell size,limit plate position,rotating speed of cell wheel and rice variety.The results showed that: a)For the rice variety of Xiushui 114,the seeds rates of small medium and large cell sizes were 3.8～6.8,7.2～11.1 and 13.0～17.9 respectively.b)For the rice variety of Huayou 14,the seeding rates of small,medium and large sizes of cell were 5.1～8.0,6.9～16.0 and 12.4～21.9 respectively.c)For the rice variety of south terrier 46,the seeding rates of small,medium and large sizes of cell were 4.7～5.8,6.5 ～14.0 and 12.2～18.2 respectively.d)For the rice variety of extra superior 338,the seeding rates of small,medium and large sizes of cell were 3.4～5.1,5.2～11.6 and 9.56～19.2 respectively.e)For the rice variety of Huang Huazhan,the seeding rates of small,medium and large sizes of cell were 3.2～5.0,4.3～13.8 and 9.0～20.4 respectively.f)For the rice variety of Meixiang Zhan,the seeding rates of small,medium and large sizes of cell were 3.0～4.8,8.3～12.3 and 13.2～17.6 respectively.g)For the rice variety of Shunliangyou 1179,the seeding rates of small,medium and large sizes of cell were 2.3～3.6,3.5～9.1 and 5.6～12.9 respectively.h)For the rice variety of Jingliangyou 1212,the seeding rates of small,medium and large sizes of cell were 3.9～5.9,4.4～12.2 and 9.4～18.6 respctively.The plastic seed metering device has similar seeding rules for different rice varieties,appropriate cell wheel can be selected for planting in light of the actual operation requirementsthe coefficient of variation was within the range which can meet the planting requirements of rice derict seeding.The optimized cell wheel is more stable and with less seeds stuck.The position of the unloading plate has a great influence on the seeding rates of japonica rice,and the position of the unloading plate can be determined according to the actual operation.Three protection belts with different degrees of cracking were used for the sowing performance tests.Results showed thatno obvious deformation was observed,the influence of degree of cracking had on seeding rates was not significant,and the selected seed belt effect was better than the prototype.(4)A 300-hour durability test was conducted on the light-weight rice precision spot hill-drop machine,the overall operation effect of the machinery and the abrasion of the seed metering group were observed and recorded every 50 hours.The test results showed that the abrasion degree of the brush and the seeding wheel increased with working time,the abrasion positions was mainly on the right of these components,which is related to the rotation direction of the cell wheel.The abrasion of the cell wheel would result in seed.The length of the seed belt was observed to be shrinked after increased,and finally local crackingwas observed.The elasticity of the seed belt affects its fitting degree of with the cell wheel.The degree of cracking does not affect the sowing effect,the bending limit plate has greater influence on the abrasion cell wheel than the straight plate,no problem was observed on the shaft and bushing during a long-time of working. |
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