Design And Experimental Study On Mechanical Weeding Device Of The Ripple Maize

Maize is one of the main food crops in China.It is not only edible for people,but also used in animal feed and industrial production.Therefore,ensuring corn production is of great significance for the development of animal husbandry and industry.Field grass damage is one of the main factors leading to the decline of corn yield.Relevant research shows that severe grass damage can reduce corn yield by more than 50%.At present,the main methods of weeding in China include manual weeding,chemical weeding,and mechanical weeding.Manual weeding is labor intensive and inefficient,and only a few areas use manual weeding methods.The chemical weeding machine has high efficiency and saves manpower.It is the current mainstream weeding method,but the chemical weeding method effectively controls the weeds and also has many adverse effects.For example,repeated use of herbicides makes the field weeds resistant and seriously pollutes the farmland environment.Pesticide residues threaten people's diet and health.In recent years,with the increasing awareness of environmental protection,mechanical weeding has gradually attracted people's attention.Mechanical weeding has the advantages of high herbicidal efficiency and low environmental pollution.Therefore,research on mechanical weeding is of great significance.Based on the analysis of the current research status of mechanical weeding technology,this paper designs the cam rocker swing Intra-row weeding device and driving rotary vibration type weeding device according to different soil environments.Combining theoretical analysis,virtual prototype design,software simulation,test optimization and other methods to optimize the performance of the designed weeding device,the main content of the research and conclusion as below:(1)Prototype design of corn mechanical weeding deviceThe ridge size of corn ridge planting and the physical parameters of corn seedlings were measured.According to the measurement results,the corn machinery weeding device prototype was designed.The prototype can complete the cultivating and weeding and loosening operations at one time.(2)Design and operation mechanism of cam rocker swing Intra-row weeding deviceAiming at the problem of low efficiency of weeding and the high rate of seedling injury in theoperation of existing cultivators,combined with the characteristics of small ridge planting of corn,a cam rocker swing intra-row weeding device was designed.The core working part of the device is the cam rocker mechanism.The design of this mechanism will be The continuous rotation of the motor is converted into the reciprocating swing of the weeding knife,so as to achieve the purpose of weeding and not hurting the seedling;the paper studies the structure and working principle of cam rocker swing intra-row weeding device,and establishes the path of the weeding knife avoiding seedlings.The mathematical model analyzes and optimizes the model to obtain the optimal trajectory of avoiding seedlings.Based on this,the key components of the cam rocker type oscillating intelligent intra-row weeding device are designed.The key components are mainly designed with weeding knives,Cam rocker mechanism design and spring design.The motion state of the cam rocker swing intra-row weeding device was simulated by ADAMS software.The trajectory of the seedling movement of the weeding device under different motion parameters was obtained,and the influence of the motion parameters on the shape of the weeding device was analyzed.At the same time,in order to explore the optimal motion parameter combination of the cam rocker swing intra-row weeding device,the cam shaft speed and the machine forward speed are used as test factors,the coverage rate and the intrusion rate are the test indicators,and the multi-factor quadratic orthogonal rotation combination design is adopted.The test method was applied to the virtual test study using ADAMS software.The results show that when the cam shaft speed is 830deg/s and the machine forward speed is 813mm/s,the coverage is 92.9% and the intrusion rate is 2.9%.The motion track of the weeding device is optimal.The ANSYS Workbench software was used to perform finite element static analysis on the weed cutter of the cam rocker swing intra-row weeding device to further optimize its structure.The static analysis results show that the rotating center hole is the weak part of the weeding knife,in order to prevent the operation process.The weeding knife has problems such as stress and strain concentration.In this paper,a knife seat is designed for each of the left and right weeding knives,and the thickness of the weeding knives is appropriately increased to minimize stress and strain concentration.(3)Experimental study on the cam rocker swing intra-row weeding deviceIn order to explore the actual working performance of the cam rocker swing intra-row weeding device,the forward speed,spring stiffness and weeding knife speed were taken as the test factors,and the orthogonal test was carried out with the herbicide rate and the injury rate as the test index.The optimal level combination was verified and compared.The results of orthogonal test showed that the working speed and the speed of the weeding knife had significant effects on the herbicide rate and the injury rate.The spring stiffness had a significant effect on the herbicide rate and the injury rate.The optimum combination is: spring stiffness 60N/mm,forward speed0.6m/s,weeding blade speed 130r/min;verification and comparison test results show that the weeding rate of the weeding device is 89.8%,and the injury rate is 2.1%.The cam rocker swingintra-row weeding device has better performance than the traditional seedling weeder.(4)Study on design and operation mechanism of driving rotary vibration type weeding deviceIn the heavy soil environment,the driving rotary vibration type weeding device is designed to solve the problems of serious rotary teeth and high power consumption during the operation of the rotary cultivator.The design of cams,springs and other components makes the weeding.The weeding knife flexibly vibrates the soil and weeds during the operation of the device,which increases the weeding performance of the weeding teeth while reducing the operating power consumption.The structure and working principle of the driving rotary vibration type weeding device are expounded and analyzed,and the working principle is theoretically analyzed.Through the establishment of the mathematical model of the motion of the weeding device,the analysis of the soil resistance of the weeding cutter and the mechanism of the drag reduction of the weeding device,the main factors affecting the working effect of the device are the machine forward speed,spring stiffness and knife roll speed.According to the theoretical analysis results,the key components such as the weeding blade,camshaft,outer roller,and spring that driving rotary vibration type weeding device are designed.The motion state of the driving rotary vibration type weeding device was simulated by ADAMS software,and the speed and acceleration changes were obtained and analyzed.The modal analysis of the driving rotary vibration type weeding device is carried out by ANSYS Workbench software to prevent resonance.The modal analysis results show that the excitation frequency of the system is much smaller than the natural frequency of the roller,and the possibility of resonance is not high.(5)Experimental study on driving rotary vibration type weeding deviceIn order to study the actual working performance of the driving rotary vibration type weeding device,Single factor,multi-factors and comparison tests were carried out in indoor soil tanks in order to obtain the optimal combination of operation parameters.Taking the machine forward speed,the knife roll speed and the spring steel as the test factors,the operating power consumption and the soil breaking rate are the performance indicators.The power consumption test of the driving rotary vibration type weeding device is carried out in the indoor soil tank.The results show that: The contribution rate of each factor to the operation power consumption is from the largest to the smallest,the speed of the cutter roll,the forward speed of the machine,the spring stiffness,and the contribution rate to the crushing rate is the spring stiffness,the speed of the knife roll,and the forward speed of the machine.The contribution rate to the herbicide rate is,from large to small,spring stiffness,knife roll speed,and machine forward speed.The optimal parameter combination is when the machine advance speed is 0.5~0.8m/s,the cutter roller speed is 241~259r/min,and the spring stiffness is10.42~12.16N/mm,the operating power consumption range is 1.89~2.0k W,and the grounding rate range is 92.9%~93.4%,Weeding rate range is 86.7%~88.5%.The verification and comparison testswere carried out in the indoor soil trough,and the results showed that the operation performance of the driving rotary vibration type weeding device was better than the conventional device.Field experiments showed that when the speed of the knife roll was 251r/min,the machine forward speed was 0.5m/s,and the spring stiffness was 10.5N/mm,the operating power consumption was 2k W,and the grounding rate was 92.8%,The weeding rate is 88.1% The designed driving rotary vibration type weeding device has the working performance to meet the operation requirements of the cultivator.