| Potato is the fourth largest commodity grain crop in the world,and the planting area and yield of potato in China have been ranked first in the world for a long time.The total potato planting area and fresh potato production in Yunnan,Guizhou,Sichuan and Chongqing account for about half of the national total.However,the mechanization degree of potato in Southwest China lags far behind the national average level,in which the total yield is only 1.84%,which is quite different from the national average level of 29.77%.The comprehensive mechanization rate in Southwest China is about 20.92%,which is only half of the national average level.The potato planting areas in Southwest China are mostly distributed in hills and mountains with drought,little rain and sticky soil,which is the natural dominant planting area of potatoes.However,the widely used small and medium-sized harvesting machines are difficult to adapt to the special planting agronomy under the difference of hilly terrain and sticky soil in Southwest China,resulting in poor separation effect during harvest,high potato injury rate,more potatoes missing and buried,and serious mechanical damage during transportation and separation.This paper relies on the major science and technology special plan of Yunnan Province: "Research and Development of Key Technologies and Equipment for Whole Mechanization of Mountain Potato".The specific research contents are as follows:(1)Resource statistics.On-the-spot investigation of planting agronomy in representative potato producing areas in Yunnan Province,and determination of soil related physical parameters.The basic physical parameters and mechanical properties of potato tuber were determined to provide theoretical basis for subsequent design.(2)Put forward the whole machine design scheme.According to the planting agronomy of the main potato producing areas in Yunnan Province,the whole machine is harvested in a single ridge of 600 mm,and the power consumption of the whole machine and key components is calculated and determined,and the traction power is calculated to be 43.21 k W.(3)Complete the design of the pressure adjusting device on the profiling ridge and the eccentric micro-vibration soil crushing device.The function of the two systems is analyzed,and the related technical parameters are determined.(4)Complete the design of the excavating device.The multifunctional curved surface shovel is designed based on bionics principle,and the working state and mechanism of the curved surface shovel are analyzed.According to the analysis results,the numerical simulation and soil groove test are completed.The numerical simulation test shows that the bionic curved surface shovel has the smallest resistance when the machine operating speed is 1.2 m/s,the excavation depth is 200 mm and the penetration angle is 15,and the resistance value is 398N;The best combination parameters of practical soil trough test are as follows: the operating speed of machines and tools is 0.8 m/s,the digging depth is 150 mm,and the penetration angle of bionic curved shovel is 15,when the resistance of bionic curved shovel is the smallest,which is 326 N.(5)Complete the design of potato impurity separation device.To solve the problem of soil viscosity and compaction in southwest hilly region,a multi-stage potato impurity separation device was designed based on the multiple separation mechanism of auxiliary separation,multi-stage separation,scattering and crushing.The movement model and dynamic model of potato miscellaneous in throwing and separating stage were established,the collision characteristics between potato miscellaneous mixture and screen surface were analyzed,and the related structural parameters and working parameters of separating screen were determined.(6)Complete the design of potato seedling separation device,vertical annular separation device and cleaning and impurity removal device.The functional design and working principle of potato and seedling separation device are analyzed and expounded The vertical annular separation device discharges the remaining stubble,seedling vine and broken soil into the field through a large squirrel-cage rotating disk with a grass belt,and determines that the vertical annular separation device is driven by a gear rack after being replaced by a bevel gear,and determines relevant structural parameters according to mechanical and kinematic characteristics;Combined with the structural characteristics of the vertical annular separation device,the design and functional analysis of the cleaning and impurity removal device are completed.(7)Trial-manufacture the prototype and complete the no-load and field test of the harvester.In the previous experiment of determining the working parameters of the separating screen,the linear velocity of each separating screen was taken as the test factor,and the impurity content and soil coverage were taken as the test indexes to carry out the quadratic rotation orthogonal combination test.With the help of highspeed camera,light filling system and triaxial attitude sensor,the distribution attitude and throwing law of the clods on the separating screen during the movement were collected in real time.The results showed that when the linear velocity of the inclinedraked finger-pointing auxiliary sieve was 1.85m/s,the linear velocity of the first-stage separation sieve was 1.42m/s and the linear velocity of the second-stage separation sieve was 2.20m/s,the corresponding impurity content and soil coverage were 1.81%and 77.92%,respectively.The field experiment is a 4-factor 5-level orthogonal experiment.When the operating parameters are forward speed 5km/h,digging depth160 mm,floating seedling removal gearing,and rotating speed of vertical annular separation device 40r/min,the rate of open potato is 96.68%,the rate of broken skin is 2.83%,and the rate of damaged potato is 1.91%.All the measured performance indexes meet the requirements of national industry standards. |
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