Design And Experiment Of Hand-held Humanoid Field Shovel Machine

With the rapid development of national agriculture,the cultivated area of crops gradually increases,so all kinds of agricultural machinery are widely used in agricultural production,and the field tillage process needs to be effectively put into use to maintain the sustainable production of agriculture.Aiming at the technology of soil tillage,scholars at home and abroad have done many researches on rotary tillage machine,such as straw stubble management,topsoil tillage,no less tillage and subsoiling.However,all kinds of rotary tillage machinery generally exist the problem of clay and grass entanglement in the process of operation,which has great harm to the tillage machinery.For example,large amounts of grass and clay lead to increased power consumption and resistance of machine operation,poor tillage quality and uniformity,and easy to cause damage to the machine and unable to work normally,which requires more time and manpower and material resources to deal with a series of problems caused by clay and grass.Therefore,in order to fundamentally solve the problem of clay and grass wrapping of tillage machines,the power consumption of operation is effectively reduced.This study will design a crank connecting rod shovel soil mechanism from imitating the artificial shovel soil process,and optimize its design.The purpose is to ensure that the tool clay is reduced and the grass is avoided in the process of operation,so as to realize low power consumption and high efficiency operation.In this study,by analyzing the process and principle of manual shoveling operation,the main advantage is that the shoveling operation does not appear the phenomenon of tool clay and grass entanglement.Therefore,a mechanical crank connecting rod structure is derived to imitate the manual shoveling process.The structural design and analysis of the shoveling mechanism are carried out,and the trajectory of the key components is described.At the same time,the walking mechanism is designed and layout,and the stability of the mechanism is verified by finite element statics and modal analysis.Based on the above design and mounted on the hand-held micro tillage rack,a hand-held humanoid field shovel without straw winding mechanism is formed.Because the structure and operation form of the shovel are inconsistent with the principle of straw winding,so as to fundamentally avoid the occurrence of straw winding.The main parameters of the soil model were determined through relevant test experiments,and the coupling simulation model between the key mechanism of the shovel and the soil particles was established by combining the discrete element and Adams kinematic simulation software.After the simulation,the torque value of the rotating shaft and the bending moment of the shovel rod under the conditions of 0.2 m/s,90 r/min and 0.3 m/s,140 r/min were obtained.According to the operation requirements,the load test system was reasonably arranged and designed,and the verification tests were carried out at 0.2 m/s,90 r/min and 0.3 m/s,140 r/min,respectively.The field test results show that the relative error between the actual operating torque value and the simulation value is 6.1384%,and the relative error between the measured bending moment value and the simulation value is 5.4356%.By analyzing the causes of the error,comparing the simulation with the actual operation process,it is proved that the prototype does not have clay phenomenon in the operation process,and more powerfully verifies the reliability and stability of the simulation system.On the basis of the theoretical prototype,the parameters of the working mechanism are optimized by simulation analysis.Through the analysis of various test methods,the uniform test design method is used to arrange the test.Taking machine forward speed,shaft speed,crank length and blade length as independent variables,blade shape as virtual variable,torque value and bending moment value as main performance evaluation indexes,the influence of each variable on evaluation index is obtained by regression analysis.Based on the regression analysis results of the two,the optimal working parameters of the shovel mechanism are obtained,that is,when the forward speed of the machine is 0.45 m/s,the rotational speed of the shaft is 140 r/min,the length of the crank is 155 mm,the length of the shovel knife is 185 mm,and the selection of the sharp angle straight shovel will have the minimum operating torque and bending moment.In order to ensure the reliability of the optimization design,the actual operation test is carried out according to the optimal parameter combination.The results show that the optimized working parameters can meet the requirements of the lowest power operation.At this time,the torque value of the shaft is 44.9734 N·m,the bending moment of the shovel rod is 59.8926 N·m,and the power consumption of the shovel is as low as 0.6593 k W.The stability coefficients of shovel depth and shovel width are 97.9322% and 93.8017%,respectively.It is proved that the optimized prototype can realize low power and high efficiency operation,and the operation process has good uniformity and stability.