Study On Optimization Design Of The Handheld Tiller’s Rotavators And Their Soil-cutting Performance

Handheld tillers are mainly used for such cultivating works as paddy field tillage,upland field tillage,pastoral management and protected agriculture tillage,etc.The rotating tilling parts,namely the rotavators,are directly driven by the drive shaft of a tiller.The rotavaror is the tillage part of handheld tiller,which is the cutting tool of handheld tiller.The quality,operability,vibration and noise,energy consumption,etc.of the handheld tiller depend largely on the design and manufacture of rotavator,and the matching of the soil-cutting parameters.The rotavator consists of some rotary blades and a shaft,with rotary blades mounted on the shaft according to a certain arrangement.The sidelong section and lengthwise section of the rotary blade undertake the soil-tilling task,and the geometric parameters of the blade directly affect the performance of a rotavator and the corresponding handheld tiller.At present,the selection and design of the rotavator is mainly based on the reference and improvement of the geometric and soil-cutting parameters of the traditional handheld tiller’s rotavator,which mainly rely on the experience and actual experiment.The shape,structure and soil-cutting parameters of rotavator(mainly is rotary blade)are different in each handheld tiller manufacturing enterprise.The performance of the whole machine is not reasonable and is lacking of the theoretical guidance.According to the imperfection of the selection and theoretical design of handheld tiller’s rotavator,as well as the imperfection of the parameters design and selection criteria of rotary blade,etc.In this paper,the key technologies of the geometric parameters modeling,scoop angle modeling and arrangement design of rotary rotavator,and the dynamic simulation of the rotary blade and rotavator in soil-cutting were researched.The shape,structure and soil-cutting parameters of the rotavator are optimized and designed to form the methods of the optimal blades selection and design for the handheld tillers.This research provides the theoretical reference for the rotavator design and performance matching of the handheld tillers.The main research results:(1)The parametric model and scoop angle mathematical model of the rotary blade were established.Based on this,the relationship between the cornerite and scoop angle of the sidelong edge was studied,and the relationship between the bending angle and scoop angle was analyzed.The results showed that,the cornerite and bending angle effect obviously on the scoop angle,and the scoop angle is positively correlated with the cornerite and bending angle,which has important influence on the soil-cutting performance of the rotary blade.(2)The finite element analysis software ANSYS/Workbench was used to analyze the static of the rotary blade.The distribution of equivalent stress,equivalent static strain and total deformation of the rotary blade were obtained.Theoretically,verifying the rationality of the rotary blade which was optimally designed by the rotary blade parameter model.(3)Based on the simulation method of SPH algorithm,the soil-cutting performance of the rotary blade was analyzed,and the influence of the angle Alpha on the soil-cutting performance of the rotary blade was analyzed and compared.Providing the theoretical reference for study the relationship between the geometric parameters and soil-cutting power consumption of the rotary blade.(4)The rotary rotavator model was obtained by optimization design.Based on the simulation method of SPH algorithm,researching on the differences of the dynamic performance and energy consumption between the optimized rotary rotavator and the traditional rotary rotavator while cutting soil.The results showed that the soil-cutting performance of the optimized rotary rotavator is more excellent,and its power is 10% lower than the traditional rotary rotavator’s.(5)The simulation power and estimated power of two sets of rotary rotavator were compared and analyzed.The results showed that the relative error is small,and it proves that the simulation method of SPH algorithm of the soil-cutting is feasible.