Design And Experimental Study On Stalk Pulling And Chopping Device Of 4YZB-4B Corn Harvester

In order to solve the problem that the stalk cutting length of corn is long in the process of pull-stalk cutting device,a pull-stalk cutting device consisting of a blade pull-stalk roller and a swinging knife was designed.The specific research of this paper is as follows:(1)Design and analysis of stem pulling and chopping device.By measuring the shape parameters of corn stalk,the average root diameter of corn stalk is 30 mm,the average plant height is 2354 mm,and the average minimum ear setting height is 1010 mm.This result provides a theoretical basis for the subsequent selection of design parameters of stem pulling roller and knife flick.This paper presents a structure in which the swing knife is located under the stem pulling roller in the stem pulling and chopping device.In view of the fact that the corn stalk cannot be pre cut when the edge type stem pulling roller pulls down the corn stalk,the blade type stem pulling roller is designed to realize the pre cutting function of the corn stalk;By analyzing the installation mode of blade type stalk pulling roller,the blade opposite installation can achieve better ability of pulling corn stalk;By analyzing the compression ratio,it is determined that the clearance of blade type stem pulling roller is 3 mm;According to the basic conditions of pulling down the corn stalk by the stalk pulling roller,the mathematical conditions are established,and determine that the width of blade type stem pulling roller is 58 mm;Analyze the rotating speed of blade type stem pulling roller;Analyze the force of cutting corn stalk with blade;The number of blades of blade type stem pulling roller is determined to be 4.The shape of the swing knife is designed to be L-shaped to realize the throwing of broken straw by the swing knife;It is determined that the layout of the swing knife is symmetrical,and the number of blades is 2;By establishing mathematical and kinematic conditions,the working length and chopping conditions of swing knife are analyzed.Through the finite element analysis software ANSYS,the sixth order modal analysis of the swing knife is carried out,and the sixth order natural frequency value of the swing knife is obtained to determine that the swing knife will not resonate during operation.(2)Dynamic simulation analysis of swing knife assembly.The movement and force of the corn stalk under the impact of the swing knife assembly are analyzed,and the virtual simulation is built with the help of the mechanical system dynamics analysis software ADAMS.The displacement and impact force of the corn stalk under different speeds of the swing knife assembly are obtained to verify the rationality of the structural parameter design of the swing knife assembly.(3)Experimental study on stem pulling and chopping device.In the experimental study of stem pulling roller scheme,the edge type stem pulling roller and blade type stem pulling roller are selected for comparative test.The test results show that the qualified rate of stem cutting length of blade type stem pulling roller is 4.34 % higher than that of edge type stem pulling roller.The single factor test was used to obtain the effects of the driving speed of the whole machine,the number of flicking knives and the rotation speed of flicking knives on the length of straw chopping.Orthogonal experiments were carried out on the forward speed of the whole machine,the number of swinging knives and the rotating speed of swinging knives when the corn harvester was working.The test results show that the importance of each parameter is:the forward speed of the whole machine > the number of flicking knives > the rotation speed of flicking knives.Under the optimal combination,the forward speed of the whole machine is 5 km / h,the number of flicking knives is 3,and the rotation speed of flicking knives is 2800 r/min.at this time,the qualified rate of straw shredding length is 96.19 %.Then a better parameter combination test is carried out to verify.Finally,through the F test,it is concluded that the driving speed of the whole machine has a significant impact on the quality of straw chopping length,and the number and speed of knife flick have a significant impact.