Research On Key Technologies And Equipment For Reducing Losses In Cutting And Threshing Of Oil Sunflower Combine Harvester

Oil sunflower is one of the four major oil crops in China,with an annual output of1.5 million tons.At present,there are still problems such as high loss rate,poor adaptability,and low efficiency in the mechanized harvesting of oil sunflower in China.Oil sunflower harvest losses mainly include header losses and threshing losses.This article combines the biological characteristics and mechanical physical properties of oil sunflower plants to study the loss reduction technology and device of oil sunflower header and threshing device.A reel header and a rib threshing device were designed.The influence of structural parameters and working parameters of header and threshing device on grain loss was explored through bench tests.Field tests were carried out to verify the harvesting performance of the header and threshing device.The following are the primary research findings:(1)Conduct research on the material feature of sunflower plants.For the “Dwarf Big Head 567DW” sunflower plant widely planted in China,measure and analyze the biological characteristics and mechanical and physical characteristic parameters.The diameter range of the oil sunflower plant disk was 100.3 mm～197.5 mm,the thickness range was 17.0 mm～22.6 mm,the weight range was 293.53 g～510.48 g,the height range was 852 mm～1053 mm,the stem diameter range was 9.9 mm～26.5 mm,the plant height range was 928 mm～1389 mm,and the thousand-grain weight range was 49.3g～60.5 g.The critical bending angle range of oil sunflower stem was 18.5°～34.07°.The maximum static friction angles of oil sunflower stem with carbon steel and rubber were25.7° and 40.1°,respectively.The experimental results of shear mechanical properties of oil sunflower stem showed that with the increase of stem diameter,the maximum shear force increased and the shear strength decreased;with the increase of stem moisture content,the maximum shear force decreased and the shear strength increased;through vibration test of sunflower disk,it is known that the excitation frequency when the maximum amplitude of sunflower disk appears in sweep frequency test is 7 Hz,and the maximum grain loss rate of sunflower disk under this excitation frequency is 1.5 %.(2)Research on the special cutting table for oil sunflower.Aiming at the problems of the oil sunflower header,such as high harvest loss rate,reel back-carrying and material blocking etc,a reel-type oil sunflower header was designed and tested.Based on the planting mode and the biological feature of oil sunflower plants in suitable harvest period,the structural parameters of grain separator,reel,reciprocating cutter and screw conveyor were determined by analyzing the dynamics and kinematics of oil sunflower plants during harvesting on the header.Taking the conveying speed,reel speed and the cutting frequency of the cutter as experimental factors,and the loss rate of oil sunflower seeds and disks as evaluation indexes,the bench test was carried out.The single factor results showed that the optimal range of conveying speed was 0.8m/s～1.4 m/s,the optimal range of reel speed was 25 r/min～35 r/min,and the optimal range of reciprocating cutting frequency was 8 Hz～10 Hz.The optimal parameters obtained from the quadratic regression orthogonal rotation combination test results are as follows: the conveying speed is 0.8 m/s,the speed of the reel is 24.1 r/min,and the cutting frequency of the reciprocating cutter is 9.1 Hz.Currently,the grain loss rate is0.95 % and the sunflower head loss rate is 0.72 %.(3)Research on the longitudinal axial flow rib type threshing device.In order to reduce grain loss and impurity content of chaff during the threshing process of sunflowers,a combined threshing device of a grooved rod threshing drum and a round tube concave screen was designed based on the principle of rubbing threshing.The structure and working parameters of the key components of the threshing device were determined through kinematic and dynamic analysis.Bench performance tests were carried out with the threshing gap,drum speed,and feed rate as test factors,and the threshing loss rate and the quality ratio of seeds in the chaff as test indicators.The single factor test results show that the optimal range of threshing clearance is 15 mm～20 mm,the optimal range of drum speed is 150 r/min～250 r/min,and the optimal range of feeding amount is 2.6 kg/s～3.2 kg/s.The optimal parameter combination obtained by the second-order regression orthogonal rotation combination test is: threshing clearance is 24.9 mm,drum speed is 244.1 r/min,feeding amount is 2.9 kg/s,at which time the grain loss rate is 2.30 % and the grain quality ratio of screening under material is82.52 %.(4)Field tests were carried out on oil sunflower cutting and threshing devices.The field experiment was carried out with the loss rate of header and threshing as test indexes.The results showed that the loss rate of header was 1.24 %～3.26 %,and the loss rate of threshing was 1.54 %～2.68 %.The analysis shows that with the increase of the forward speed of the whole machine,the header loss rate and threshing loss rate decrease first and then increase.When the forward speed of the whole machine is 1.1m/s,the whole machine has better harvesting performance.Currently,the grain loss rate and grain impurity rate are 1.13 % and 0.95 %.