Design And Experimental Study Of Walnut Picking Machine

The diversity of the planting pattern of walnut determines the diversity of the picking mode,so the direct introduction of foreign fruit harvesting machinery is too limited,which can not solve the problem of the domestic walnut collection.And most of the forest and fruit machinery are harvested by the way of vibrating fruit,which can improve efficiency and reduce labor intensity to a certain extent,but most of these methods use the forced main trunk to shake the fruit,which can cause the fruit to fall off and cause damage to the tree.So it is of great significance to design a simple and compact walnut harvester with simple and compact structure,safe and reliable performance,convenient operation and high picking efficiency.Therefore,the main research content of this paper is to design and develop portable walnut picking equipment suitable for Yunnan mountain area,and to verify the rationality of the equipment through simulation analysis and performance test.This paper is based on the research of the cooperative research project of Yunnan Academy of forestry science and the Modern Agricultural Engineering College of Kunming University of Science and Technology.The contents and conclusions are as follows:(1)The physical parameters of Yunnan walnut tree need to be studied first.The proportion of lateral branch diameter in[80,120)is 70%,the proportion of[60,80)is13.33%,the proportion of side branch height in[1.50,3)is 84.99%;the proportion of two grade side branch diameter in[80120)is 16.67%,the proportion of[60,80)is 20%,and the proportion of two side branch height in[1.50,3)is 60%.The proportion of crown diameter in[13.00,14 is 40%,the main concentrated distribution area is[11.00,14);the density range of branches is 1.062~1.110g/cm~3,the average value is 1.089g/cm~3,the range of water content is 35.0%~38.7%,the average value is 36.5%.The elastic modulus range is732.97~1491.85MPa,the average value is 1150.47MPa,the elastic modulus range is207.52~387.13MPa under the compression state,and the average value is 282.64MPa.The critical value of separating force of walnut stalk is 58.2N,and the quality range of walnut fruit is 45.25~84.86g,and the average value is 68.78g.(2)Aiming at these characteristics,three kinds of overall design plan of picking machine are put forward.After comparison and analysis,the final selection plan is compared with program two.The first one is based on the vibratory walnut picking machine on the side branch of the tree body.The scheme two is based on the rocking walnut picking machine of the two grade side branch of the tree body,and the three-dimensional model of two kinds of machine is created,and its composition and working principle are described in detail.(3)The controllable speed range of the vibrator is 600~3000r/min,the basic frequency is 10~50Hz,the speed range is controlled in 1200~3000r/min,which can avoid the low natural frequency of the tree body,thus reducing the damage of the tree body.The order of the three influencing factors is:load frequency B>position,C>excitation force A,and the best combination is.That is,the exciting force is 700N,the load frequency is 15Hz,and the location is 1200mm.When the speed of gasoline engine is 2500r/min,the effect of simulated harvest is the best.The relationship between acceleration amplitude and harvest effect is parabolic in general,which is similar to the effect of excitation force in harmonic response analysis.(4)The best working parameters are obtained:the excitation frequency is 20Hz,the excitation force is 800N,the excitation position is far away from the branch point of the lateral branch,and the extraction effect under this condition is the best,and it can reduce the damage to the tree body.Through the best working parameters,it is found that the range of the picking rate is 63.9%~74.8%,the average value is 67.7%,the range of the residual fruit rate is 25.2%~36.1%,the average value is 32.3%.Scheme two picking machine is the best picking effect at the speed of 2500r/min in gasoline engine,the range of picking rate is78.16%~85.19%,the average value is 82.17%,the range of residual fruit rate is14.81%~21.84%,and the average value is 17.83%.The picking effect of scheme two is better than that of scheme one picking machine.However,from the comparison of the overall effect and operation efficiency,the scheme one picking machine is better than the scheme two picking machine.From the actual picking effect,the two picking machines basically reached the picking requirement of Yunnan walnut.This research provided two kinds of picking machines for walnut mechanized harvesting in Yunnan.