Design And Experiment Of Double-acting Cutter With Planet Gear Driver For Rape Harvester

As main oil crop in China,rape is the main raw material of edible vegetable oil and the ideal raw material of biodiesel.It has tall and thick stems with intertwined branches and the mature pods are easy to crack,which bring about the problems of high loss rate and large power consumption for the rape mechanized harvest.Traditional rape harvester adopts the crank-link driven or sway ring mechanism driven single-acting reciprocating cutter,which has great vibration and disturbance to the rape stems,resulting in large loss of rapeseed on the header.In this paper,in order to solve the above problems,a kind of reciprocating double-acting cutter and planet gear driver ware designed creatively based on the study of the dynamic characteristics of the existing cutting mechanisms and bench experiment of rape stalk cutting.The new designed cutting mechanism has stable transmission,compact structure,high transmission efficiency and little disturbance to the stalks of rape.The main work and achievement of this paper are as follows:1.The working performance of different mechanisms of reciprocating cutter,slip cutting theory and stalk holding conditions ware studied.Analysis showed that traditional cutting mechanisms of crank-link and sway ring mechanisms have the problems of low transmission efficiency,lateral force on the cutter rod,and large vibration;planetary gear driven cutter has the characteristics of high transmission efficiency,high working reliability,small vibration,and no lateral force on the cutter rod.The labor-saving mechanism of sliding cutting mode was studied,analysis result provided theoretical support for choosing low-power cutting mode;physical and mechanical properties of rape stalk and its influence on cutting ware analyzed,which provided theoretical basis for choosing appropriate type of reciprocating cutter blade.2.A bench experiment of rape stalk cutting was carried out with crank-link single-acting cutter,double-acting cutter and different blades.The theoretical analysis results showed that double-acting cutter has stronger inertia force balance ability,lower power consumption and less disturbance to rape stalk than the single-acting cutter,which is beneficial to the rape mechanized harvest.The single-factor experiment results showed the power consumption of crank-link double-acting cutter was about 22% to26% lower than that of single-acting cutter,the cutting ability of tooth blade was stronger than that of smooth blade,the cutting ability of long tooth blade was stronger than that of short tooth blade and the difference of power consumption between them was small.The Box-Benhnken center combination test method was used to study the parameters of the long-blade double-acting cutter.Design expert 8.0.6software was used to analyze the test results,and a response surface optimization mathematical model was established.The optimization results showed when the cutting speed was 1.17m/s,the straw conveying speed was 0.98m/s,and the cutting height was 400 mm,the optimal working parameters ware as follows: cutting success rate was 99.99%,the cutting efficiency was 48.87 pieces/s,and the cutting power was 918.14 W per unit cutting width.3.The planet gear driver and double-acting cutter ware designed and analysed.With the CAD software of Solid Works,Auto CADmechanical and so on,the planet gear driven double-acting cutter was designed,and its kinematics and dynamics ware analyzed.The basic parameters of the bevel gear and the planet gear ware optimized by using the genetic algorithm in MATLAB,so that the structure was more compact and the weight was lighter on the premise of meeting the strength requirements.The inertia force and cutting resistance of the newly designed cutter ware analyzed.The results showed the inertia force balance performance of the new cutting mechanism was good,which was helpful to reduce the vibration of the header.The analysis results of the cutting diagram of the newly designed cutter showed that the cutter had the advantages of high cutting continuity,uniform load and small disturbance to rape stalks,which ware conducive to vibration reduction and reducing the rapeseed loss of header.4.Prototype production and the no-load vibration test of header was carried out.The vibration test results showed that cutter had a significant effect on the vibration of the header,and the planet gear driven double-acting cutter caused less vibration to the header than that of the crank-link single-acting cutter did.Vibration acceleration of header with newly designed cutting mechanism in the direction of reciprocating motion of cutting cutter was 49.1%~52% less than that of original header with crank-link single-acting cutter.5.Vibration and rapeseed loss rate of header in operation state in the field ware tested.The newly designed cutter and the crank-link single-acting cutter were separately installed on the header of rape harvester in order to test the vibration and rapeseed loss rate of header with different cutters.The results of vibration test in the field showed that the average vibration acceleration of the header equipped with the planet gear-driven double-acting cutter was 48.1% less than that of the header equipped with crank-link single-acting cutter at the same test point in the direction of movement of cutter,which proved that the vibration caused by the planet gear-driven double-acting cutter in the reciprocating direction of the cutter in the actual rape combine harvest process was significantly less than that of the ordinary reciprocating cutter.The test results of rapeseed loss rate of the header showed that the newly designed planet gear-driven double-acting cutter could significantly reduce the rapeseed loss compared with the crank-link single-acting cutter.The rapeseed loss of the header equipped with the newly designed cutter was 42.5% lower than that of the header equipped with the crank-link single-acting cutter at the speed of the harvester in the range of 0.6m/s to 1.4m/s.Based on the research of the existing cutting mechanisms,a planet gear driven double-acting cutter was designed creatively.Experiment results showed that the newly designed cutting mechanism had good smooth performance and low vibration,and reduced the rapeseed loss rate of header remarkably.The design and relative experiment in this paper provided a successful example for improving the cutter and its driver of rape combine harvester to improve its efficiency and reduce the rapeseed loss of header.