| Mechanized harvesting of sugarcane has the advantages of high efficiency,low harvesting cost and low labor intensity,which is an inevitable trend for the development of this industry.At present,the mechanization level of sugarcane harvesting in China is low,and the sugarcane is affected by typhoons and monsoon winds,the sugarcane will fall down to different degrees every year,and there are common problems such as low efficiency of lifting the sugarcane stalk,easy to slip,and serious breakage of the lodged root cutting during the operation of the cane-holding-cutting system(cutting table)of the harvester.In this paper,through theoretical analysis,simulation and experimental research,the mechanism between sugarcane stalks and the cane holder and cutter is initially elucidated,a mathematical model of sugarcane stalks against overturning is established,a suitable operation method and operation parameters for mechanized harvesting under overturned sugarcane conditions are explored based on the optimization of the parameters of the spiral cane holder,the analysis of the mechanism of cutting and breaking of sugarcane stalks and the multi-objective optimization of the double-disc cane cutter are carried out,and a multi-purpose optimization of the cane holder and cutter is carried out.The multi-objective optimization of the cutter was carried out,and the influence mechanism between the height of stalk lifting and the level of lodging cutting and breaking was investigated.The main research works are as follows.(1)By analyzing the agronomic conditions and plant growth characteristics of sugarcane in the main production areas,macroscopic parameters such as planting density and height of sugarcane plants as well as stalk diameter,moisture content,and modulus of elasticity were measured using direct measurement methods.Radial and axial compression tests,torsion tests,and tensile tests of the cane bark were carried out on the roots of the sugarcane stalks.The physicochemical properties of the stalks were analyzed by applying electron microscopy scanning techniques and staining with saffron solid green.The results showed that the sugarcane epidermis had the highest degree of lignification and the vascular bundles in the mechanical tissue layer were closely distributed,which could enhance the mechanical strength and resistance to overturning of the stalks.(2)A mathematical model of sugarcane stalk overturning resistance was established to clarify the interaction mechanism between sugarcane stalks and the cane supporters and cutters.Based on the mechanical model of sugarcane field growth,a mathematical model of the critical collapse moment,wind force and wind speed of sugarcane stalk under standard wind pressure and air pressure was established to clarify the causes of stalk collapse and the mechanism of collapse resistance.The kinetic equations for the field operation of the cane lifter and the double disc cutter were established through theoretical analysis,and the lifting mechanism of the spiral cane lifter on the stalk,the motion mechanism of the double disc cutter under vibration conditions and the analysis of the influence parameters on missed cutting and recutting were clarified.(3)Parameter optimization of the screw-type cane lifter was carried out to explore a suitable operation method and operating parameters for mechanized harvesting under severe overturning conditions.Based on the open screw conveyor theory and rigid-flexible coupling simulation,we analyzed the reasons affecting the operating efficiency of the cane lifter and carried out the parameter optimization.Based on the rigid-flexible coupling simulation,the experimental study on the influence of different forward speed and lateral deflection angle on the vertical height of sugarcane stalk center of mass was carried out,and the field test showed that the average error rate with the simulation was 5.41%,and the results concluded that the order of preferential selection of sugarcane inverted posture during the operation of the harvester should be side reverse inverted,side inverted and side smooth inverted,and the reasonable operation speed was explored for different inverted postures.(4)The cutting and breaking mechanism of sugarcane stalk was analyzed,and experiments and multi-objective optimization of double-disc cutting were carried out.Using the UMAT subroutine of the secondary development function of ABAQUS software,a simulation model of sugarcane stalk and cutter with anisotropic material properties was established.Based on the variation of stresses and the transfer characteristics of force waves,it was found that the variation of tensile and compressive stresses on the cutting surface and back side of the stalk during cutting was the main cause of stalk breakage and tearing,especially in multi-blade cutting,and the defects of rectangular blade cutting were found.Based on the established finite element cutting model,the influence laws of blade inclination,blade speed and forward speed on the maximum cutting force,maximum blade amplitude and maximum shear force were investigated,and the mathematical model of the influence of test factors on the indexes was constructed.The multi-objective optimization equation of the double-disc cutter was established,and the multi-objective optimization of the double-disc cutter was carried out based on the micro-particle swarm algorithm,and the best combination of parameters after rounding was 12° of cutter inclination,630 rpm of cutter speed and 4 km/h of forward speed,and the accuracy of the best combination of parameters was verified by the cane-cutting system test platform and high-speed camera technology.(5)The influence mechanism between the lifting height of the cane support on fallen cane and the cutter’s breakage level on lodging cut was investigated.Based on the designed test platform of the cane cutting system,the experimental study on the influence of the cane lifter on the lifting height of different inverted sugarcane and the cutter on the breakage grade of stalk cutting was carried out,and the average breakage grade of stalk≤1.6 was selected as qualified.1.0m,and the inverted angle of 45° after lifting the inverted cane can be used to evaluate whether the operation effect of the cane lifter is qualified. |
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