Design And Experimental Study On Gap-adjustable Combined Ear-picking Mechanism Of Corn

In China,the corn usually gained high moisture during the harvesting because of the limitation of the climate,the variety breeds and the cropping system,which might cause great loss of gain if the directly threshing is used.Therefore the harvester to pick the corn ears is desired.Aiming to decrease the rate of impurities and improve the applicability to various stalk diameters,we developed a new picking mechanism characterized by the adjustable gap between two picking plates so as to meets the requirement of corn production.The gap-adjustable combined ear-picking mechanism of corn was designed based on the traditional combined ear picking mechanism taht consisting of ear picking plate and the stem pull roller.The feasibility of the design of gap-adjustable combined ear-picking mechanism and the four blade clearance stem roller was verified by analyzing the contact model of corn plant stalk,corn ear and pick the ear plate.The key components of plate picking instrument were designed.The adjusting gap was determined as 18-40 mm by measuring the physical parameters of the stalk.The structural parameters of the stalk rollers were obtained by analyzing the process of picking ears.The auxiliary and transmission mechanism were designed at the same time.The optimum combined working parameters were determined by the bench tests for the plate picking instrument at the forward speed of 5 km/h,the rotary speed of 750 r/min,the rake angle of 15°and the gap between two picking plate of 5 mm.The novel plate picking instrument was compared with the conventional plate picking instrument that the gap between two picking plate was not adjustable by experiments.Results showed that the picking plate is profit for decreasing the ratio of impurities.By analyzing the working condition and picking process of the ear-snapping plate of low-impurity corn ear-snapping plate mechanism during the ear-picking process,the segmented length designed optimally of ear-snapping plate was determined,and the bench test on the segment-combining ear-snapping plate was carried out.The test showed that the segment-combining ear-snapping mechanism can reduce the impurity rate.With the analysis of working time sequence of the four-blade stalk-pulling roller,the optimization scheme of increasing stalk-pulling ribs and increasing stalk-pulling blades was determined.The angle between the ribs and the adjacent stalk-pulling blades was examined to increase by means of ADAMS simulation.Based on the calculation of the minimum angle between the adjacent stalk-pulling blades and the minimum diameter of the stalk-pulling roller,the minimum numbers of stalk-pulling blades and the minimum diameter of the tapered stalk-pulling roller were determined.The optimal combination of the pull-stem-roller type and ear-snapping-plate type was also acquired.The tapered stalk-pulling roller and our-blade four-rib stalk-pulling roller were used to implement the impact test of the ear and ear-snapping plate respectively,which proved that the tapered roller reduced the impact force of the ear and ear-snapping plate.Through the analysis on the ear-picking process,the structural size of the segment-cone stalk-pulling roller was determined.The result showed that the minimum impurity rate of the tapered stalk-pulling roller was only 0.56%.Field test showed that the four-blade four-rib stalk-pulled roller was applied optimally;When the whole-adjusting-clearance ear-picking plate combined with eight-blade-segment-cone stalk-pulling roller,the ear-picking performance was better;The combination of the segment-adjusting-clearance ear-picking plate and eight-blade-segment-cone stalk-pulling roller or six-ribbed roller is the best combination.The impurity rate of the segment-adjusting-clearance ear-picking plate and eight-blade-segment-cone stalk-pulling roller was decrease of 3.22%compared with the traditional picking pan and stalk-pulling roller combined picking mechanism.The machine damage tests were conducted on the auger and lifting mechanism of the corn harvester.The results of the test showed that the dragon and lifting mechanism would cause some mechanical damage to the corn ear with an average mechanical damage rate of only 0.01%.