Research On Electric Handheld Tiller Analysis And Design

Electric handheld tiller is driven by motor.It is mainly used for upland soil preparation,pastoral management and agricultural facilities work operations,its power is not more than 7.5k W,and the rotary tiller is installed directly on the drive axle.The electric handheld tiller has the characteristics of flexibility,portability and multi functions of traditional handheld tiller.It is suitable for farming in small or medium-sized fields such as mountain areas and hills.It is also suitable for planting tobacco,tea and other economic crops.It also has the advantages of economy and environmental protection and large market demand.It has great significance to study the electric micro tillage machine in order to improve its operation safety,performance stability,component reliability and operation simplicity.In order to study the electric handheld tiller and know its structure principle,a type of handheld tiller was disassembled measured and drawn,and its three-dimensional model was established.Then the statics analysis and modal analysis of the frame are carried out,and the total deformation of theframe,the equivalent stress cloud and the first six order modal parameters are obtained.The comparison of the excitation frequency and the inherent frequency of the frame of the electric handheld tiller indicates that when the micro tillage machine works steadily,the natural frequency of the motor,the gearbox and the rotary tillage cutter roll will not coincide with the natural frequencies of each stage of the frame,and the resonance will not occur.According to the results of the modal analysis,the structure of the stiffeners and supporting plates is designed at the part of deformation of the frame and the single objective optimization is carried out,which reduces the maximum deformation amount of the first few steps of the frame.The maximum deformation quantities of the first,second order were reduced by 5.58% and30.44% respectively.In addition,the natural frequencies of each step were raised.As a whole,the dynamic structure strength and stability of the frame were improved.The service life of the machine was also prolonged.After a full understanding of the structure and principle of the handheld tiller,on the basis of some references,some problems in the existing electric handheld tiller is finded,such as the centre of gravity of the handheld tiller is too close to the front,the the turned handheld tiller may cause an accident,insufficient frame strength,and the long-placed batteries will be damaged.In view of the problems,a new type of handheld tiller has been designed and the main components are selected.Its integral frame structure has higher strength and can bear more traction force.A special wire box prevents the line frombeing exposed.The battery box is arranged in the appropriate position,it is convenient to assemble and disassemble,make full use of the battery in slack seasons.The finite element statics analysis of the frame of the new electric handheld tiller was carried out,and the results show that the strength and stiffness of the frame meet the requirements.In the light of the manual and retractable operation of the front leg of the handheld tiller is hard and tedious,and the the turned handheld tiller may hurt people,an automatic lifting device was designed.The device adopts a mechanical transmission scheme combined with spur gear and screw drive.The structure and working principle of the device are introduced.The parameters of the screw and motor are designed and calculated.Then the kinematics simulation of the device is carried out,and the results show that the movement of the device meets the design requirements.Aiming at the problems that the manual control handheld tiller is inconvenient and hard to operate,and unskillful or improper operation can easily lead to accidents,the transmission scheme of electric handheld tiller based on electromagnetic clutch is designed.In the scheme,the operation buttons are arranged on the control panel of the handrail,so that the operation is simple.Finally,a control program is designed,which makes the action of electric micro tillage machine meet the requirements of safety operation on program control,and it improves the safety of electric micro tillage machine.At last,the main technical specifications of the electric handheld tiller areintroduced,and the tillage performance test is carried out according to the relevant standards.The test results show that the developed electric handheld tiller meets the relevant standards.