| Water chestnut is one of the important aquatic vegetables in China,which has a wide planting area,long history of cultivation,crisp taste,high nutritional value and high planting economic benefits.The manual harvesting of water chestnut requires the straw covering the surface to be removed from the field before digging and harvesting,which has problems such as high labor intensity and low operational efficiency,especially in the harvesting season when a large amount of labor is required,resulting in high labor costs,which to a certain extent restricts the development of water chestnut planting industry.In order to solve the above problems,this paper designed a selfpropelled water chestnut stalk harvester based on the planting system as well as harvesting requirements,based on the growth characteristics of water chestnut stalks during harvesting as well as mechanical characteristics,to complete the operation of water chestnut stalks leaving the field and provide better operational conditions for subsequent manual or mechanical harvesting of water chestnut.The research contents and conclusions are as follows:(1)Research on water chestnut planting system and the mechanical characteristics of water chestnut stalks during harvesting period.The average length of water chestnut stalks reached 1290 mm,the diameter of stalks ranged from 3 to 5 mm,and the diameter of stalks started to decrease from the bottom,and the stalks also had the same nodules as those of rice,with an average of 83 mm.The results of the water chestnut stalk shearing and bending tests showed that the bending and shearing forces of the stalk decreased as the stalk part rose,and the bending and shearing forces at the bottom of the stalk were the largest,with a maximum average bending force of 0.89 N and a maximum average shearing force of 24.4 N.(2)Overall scheme design of self-propelled water chestnut stalk harvester.The overall design of the self-propelled water chestnut stalk harvester based on the crawler chassis,paddle wheel,cutting device,intermediate conveying device,linear guide,and collection box was proposed based on the operational requirements of water chestnut stalk harvester,which completes the functions of holding up,cutting,conveying,and collecting water chestnut stalks to realize mechanized harvesting of water chestnut stalks.On the premise of following the overall structure,the layout design of the hydraulic transmission system of the whole machine was carried out.(3)Design and analysis of key components.The reciprocating cutting device was selected,and the driving mechanism of the national standard II cutting device was a crank linkage mechanism,and through the motion analysis of the cutting blade,the feed distance was 75 mm,the cutting speed of the moving blade was 0.89 m/s,and the speed at shearing was 1.3 m/s,which basically meets the design requirements.The chain rake type conveying device is selected,the width of the design is 800 mm,two roller chains are used,and the angle between them and the cutting table is 40°,which is convenient for the stalk conveying.The developed linear slide slide mechanism can realize the lifting of the whole cutting table with the maximum lifting height of 300 mm,and the models of slide and slide are HG20 and HGH20 CA,and the load capacity can reach500 kg.(4)Simulation analysis of key components.The kinematic simulation of the paddle wheel was carried out using Recurdyn software,and the analysis determined that the paddle wheel speed ratio λ=2,the maximum speed of the tip of the spring tooth in the z-axis is 2 m/s,and the maximum speed in the x-axis is 3.3 m/s,which is suitable for the range of action of the paddle wheel and the speed of the paddle wheel;the kinematic analysis of the cutting device showed that the maximum cutting speed is 1.5m/s,and the average cutting speed The maximum cutting speed was 1.5 m/s and the average cutting speed was 0.9 m/s,which basically met the design requirements.Recurdyn software and EDEM software were used to simulate the coupling between the paddle wheel and the stalk,and the results showed that the paddle wheel with a large paddle speed ratio and a lower popping tooth away from the lower paddle wheel had a large force on the stalk,which was consistent with the theory.(5)Self-propelled water chestnut stalk harvester performance test.The prototype of self-propelled water chestnut stalk harvester was tested,and all parts of the prototype were measured to be in normal operation and could achieve the working effect.The performance verification test was conducted on the paddle wheel,and the feeding rate of the stalk and the winding rate of the stalk were taken as the performance indexes.The test results showed that when the paddle wheel paddle speed ratio was 2.0,the feeding rate of the paddle wheel to the stalk reached 85.5 % and the winding rate of the stalk was 2.6 %,and the best performance of the paddle wheel was achieved when the paddle wheel was paddled along the stalk,with the feeding rate of the paddle wheel being 88 % and the winding rate of the paddle wheel being 2.2 %.The design quality target was achieved and the rationality of the wheel design was verified. |
