| Oil sunflower is an important oil crop in my country.Its planting area is as high as 4million hm~2.The existing oil sunflower mechanized harvesting equipment has poor adaptability,low intelligence level,high loss rate,which make it difficult to meet the needs of oil sunflower operations,thus restricts the development of the oil sunflower industry.Therefore,it is very important to develop special harvesting equipment for oil sunflower.This paper took the oil sunflower in the middle and lower reaches of the Yangtze River as the object,combines its biological and mechanical characteristics,analyzed the mechanized harvesting process of oil sunflower,designed a chain-type oil sunflower header,Theoretical analysis and experimental research on the key parts of the header,on the basis of optimizing the cutting device and the clamping and conveying device,the chain-type oil sunflower cutting table and the whole machine were developed.In order to inspect the operating performance of the header and the whole machine,field performance tests were carried out.The main research contents are as follows:(1)The biological characteristics of oil sunflower plants were measured and analyzed,the parameters were obtained such as the critical angle of plant bending is17.93°?56.85°,the planting row spacing was 400?600 mm,and the plant spacing is200?360 mm,the plant height range is 1201?2104 mm.According to the measurement and analysis of the biological characteristics of the sunflower,the parameter range were gained such as the diameter of the sunflower is 100.2?260.2 mm,the weight of the sunflower is 155.2?1028.9 g,the thickness of the sunflower is14.3?36.1 mm,and the thousand-grain weight is 52.2?66.4g,the height of the disc ranges from 311 to 1810 mm.Experiments on physical characteristics of oil sunflower"DW667"stems showed that,except for the insignificant changes in bending strength,the maximum shear force,bending force,and compression force of the stalk gradually decreased from root to tip.As the diameter increased,the shear force,bending force,and compression force gradually increase.Among them,the root diameter of the stalk was the largest,and the shear strength was the largest,so the power consumption for root cutting was greater.The friction characteristic test showed that the maximum friction angles between the stem and carbon steel and stainless steel were 29.5°and 28.3°,respectively.Therefore,when carbon steel or stainless steel was selected as the cutter material,the selected blade-shaped sliding angle should be greater than the maximum sliding friction of 29.5°.The grain collision test showed that the order of the coefficient of restitution between the grain and different materials was:Q235>aluminum alloy>organic glass>rubber.In order to reduce the splash loss of the grain,rubber should be used as the anti-splash wrapping material for the header.(2)Based on the distribution characteristics of oil sunflower planting in the middle and lower reaches of the Yangtze River and the biological characteristics of oil sunflowers,the mechanized oil sunflower harvesting process was analyzed,the overall layout was determined by summarizing the operating procedures of oil sunflower plants in the header.Compared and analyzed the different schemes corresponding to the technological processes of cutting,reeling,screw conveying,and walking mode.Compared and analyzed the different solutions corresponding to the technological processes such as cutting,reeling,screw conveying and walking methods.Combined with the biological and physical characteristics of oil sunflower planting,the reeling form of flexible clamping and conveying,the rotary cutting with a constant sliding angle and telescopic lever type screw conveying methods were determined.Based on the scattered,small and uneven distribution of oil sunflower planting areas,the crawler-type chassis walking mode was determined.The telescopic rod type screw conveyor was designed,Through the analysis of screw conveyor and material kinematics and dynamics,it was determined that the helix angle was?_q=50°,the drum speed was 180 r/min,the outer diameter was 450 mm,the inner diameter was 250 mm,the pitch was 320 mm,the eccentricity was 60 mm,the lever length was 225 mm,the eccentricity was 60 mm,and the length of the telescopic lever was 225 mm.The division mechanism was designed,the process of plant division was analyzed,and the horizontal cone angle and vertical cone angle of the cone division head were determined to be 30°and 25°,respectively.(3)Aiming at the disadvantages of the existing cutters in cutting oil sunflowers,such as high power consumption,easy plant vibration,and knife jamming,based on the logarithmic spiral mathematical model,a rotary sliding cutting device with constant sliding cutting angle was designed.The key parameters of the cutter were analyzed,and it was determined that the diameter of the cutter head was 150 mm and the minimum number of blades was 3.Analyzed the clamping and cutting process,it was clear that the relative position range of the cutter and the active feeding wheel was:-215mm?X?305 mm.By analyzing the sliding cut and the conditions of no sliding cut,it was concluded that the applicable range of the sliding cut angle was:29.5°???61.5°.The stalk cutting process was analyzed,and the stalk cutting power consumption model was constructed,thus the key factors affecting power consumption were found to be sliding angle,rotation speed,relative position and other factors.A bench test was carried out with the cutting power consumption and the falling particle loss rate as the evaluation index,the single factor test clarified that the optimum speed range was 750?1050 r/min,the sliding cut angle range was 50°?70°,and the relative position range was 100?300 mm.The quadratic regression orthogonal rotation combination test showed that the optimal parameter combination was:the cutter blade sliding angle was 61°,the cutter speed was750 r/min,and the relative position between the center of the drive sprocket and the cutting installation center was 180 mm.(4)In order to reduce the splash loss of the oil sunflower transmission process,a flexible holding conveying device is designed based on the flexible collision principle.Through analyzing the working process of the clamping chain,it was clear that the center distance of the driving and driven sprocket was 800 mm,the forward inclination angle of the chain was a_b=25°,and the backward inclination angle of the chain was a_h=42°.The structure analysis of the clamping element determined that the height of the clamping element was 45 mm,the width of the clamping element was 76 mm,and the width of the clamping element was 80 mm.Carried out the analysis of the reeling,clamping,conveying,and throwing process,the plant statics model,dynamic model and kinematics model were constructed.It was found that the key factors affecting the clamping and conveying effect were the clamping speed ratio,clamping gap,and clamping speed.Taking the clamping speed ratio,clamping gap,and clamping length as investigative variables,the bench test was carried out based on the evaluation index of plant transportation success rate and shattering loss rate.The single factor test clarified that the optimal clamping gap range was 20-40 mm,The clamping speed ratio was 1.2-1.6,and the clamping length was 250-450 mm.The optimal parameter combination was obtained by the quadratic regression orthogonal rotation combination test was that:the clamping gap was 20 mm,the clamping speed ratio was 1.3,and the clamping length was 345 mm.(5)In order to test the rationality of the design of the key components of the header,field experiments were carried out based on the evaluation indicators of the success rate of plant transportation and the missed cut rate.The results showed that the conveying success rate was 82.2%to 85.5%,and the missing cut rate was in the range of 3.4%to4.6%.The clamping conveying device and cutting parts can meet the requirements of the operation.To test the performance of the header and the performance of the combine harvester during the ripening period of the oil sunflower,the field experiments were carried out on the evaluation indicators of the kernel loss rate,the kernel fragmentation rate,and the kernel impurity rate,The results showed that the loss rate was 3.1%to 4.1%,the kernel fragmentation rate was 2.2%to 2.9%and the impurity rate was 3.2%?4.1%respectively,which showed that the faster the walking speed,the higher the kernel loss rate,the broken kernel rate,and the impurity content rate.Taking into account comprehensively,the machine walking speed was not higher than 0.8m/s,and the kernel breakage rate,kernel loss rate and impurity rate were not more than 4%,which basically meet the operation requirements. |
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