| In the multi-crop rice production area in the middle and lower reaches of the Yangtze River,the rotary burial blade roller can solve the problem of entanglement and blockage when the high stubble straw is returned to the field under the environment of hardened clay soil.However,there are still problems such as high power consumption,unstable operation,and insufficient straw burial depth,so the purpose of this paper is to reduce the resistance and enhance the quality after tillage.Specifically,the discrete element model of rotary power consumption prediction was established to analyze the working mechanism and interaction mechanism of blade roller,and the way to improve the performance of blade roller was obtained.Based on this,reasonable design and optimization of the original blade roller structure and tool parameters are carried out.Finally,field tests were conducted to investigate and analyze the regional applicability of the blade roller.(1)Based on the discrete element method,a prediction model of rotary tillage power consumption the paddy stubble field was constructed to assist the detection of power consumption of the rotary burying blade roller.According to the monitoring of soil moisture content in the paddy stubble field for three consecutive years,it was found that the soil moisture content was close to its plastic limit,which indicated that the soil plasticity in the paddy stubble field was poor.Combined with the form of soil damage,Hertz Mindlin with bonding particle contact model was selected to characterize the adhesion and damage of the soil in the paddy stubble field.In view of the particularity of rotary tillage operation and the structural characteristics of the rotary burying blade roller,the scale of the blade roller was reduced along the width direction,and the calibration reference test was completed with the help of rotary tillage test platform.In the discrete element software,the model of rotary tillage was established,and the functional relationship between contact parameters and power consumption index was established through the equal step climbing test.Combined with the power consumption value of calibration reference test,the contact parameter value of the rotary tillage power consumption prediction model in the paddy stubble field was finally determined,and the model was established.In order to further verify the applicability of the model,the error comparison test was carried out on the universal blade roller and the rotary burying blade roller under different working conditions.The results showed that the average prediction error was 6.65%,and the range was between 3.63% and 9.48%.Combined with variance analysis,the prediction model of rotary cultivation power consumption in paddy stubblefield was suitable for the prediction of power consumption under different rotary cultivation blade roller and working conditions.The average error of power consumption prediction of the real scale field test of reduction roller was 7.28%,and the range was between 2.50% and 12.81%.In the process of scaling,the error of the roller structure changed little,which showed that the model could be used in the field test.(2)The main research object is the helical transverse blade,which is the core tool in the rotary burial blade roller.By constructing a mathematical model of the blade,analyze the process of rotary cutting soil and rotary burying straw to reveal the operation mechanism of blade rollers,and provide theoretical basis for the subsequent optimization design of reducing the resistance and enhancing the quality.According to the process of soil cutting with helical transverse blade,the dynamic variation of cutting angle and sliding angle with rotation angle was analyzed.The dynamic parameters range from ±3.37° to ± 9.02° under normal operation conditions.In order to avoid the occurrence of negative clearance angle during operation,the static clearance angle should be greater than 9.02°.In the simulation test study of the influence of the cutting angle on the power consumption,it can be seen that the power consumption of the helical transverse blade decreases first and then increases with the increase of the static cutting angle,and when the static cutting angle is between 30°?40°,the operating power consumption is lower.In order to further analyze the distribution of power consumption in the entire operation stroke,the process of soil cutting with helical transverse blade is divided into two parts: cutting and throwing,and the end point of furrow slice is the demarcation point.Based on the discrete element model,the influence of tillage depth,traction speed,and blade width on the power consumption of cutting and throwing soil was analyzed.The simulation results show that the power consumption of soil cutting is far greater than that of throwing soil.With the increase of tillage depth,traction speed,and blade width,the power consumption of soil cutting and throwing stroke increases,while the change of throwing soil power consumption percentage is increasing,decreasing and not obvious.The results show that tillage depth has more significant effect on soil cutting power consumption,traction speed has more significant effect on soil throwing power consumption,and blade width has the same effect on both.Aiming at the process of rotary burying straw with helical transverse blade,the effects of the blade on straw were analyzed from the vertical and horizontal directions respectively,and the principles of rotary burying and returning to the field of stalk suppression burying,rubbing and mixing,and throwing soil covered was revealed.Through the force analysis of straw upright and lodging,when the blade sliding cuttingangle is less than the friction angle between blade and straw,the straw does not slide along the blade side,which meets the operation requirements of helical transverse blade.By analyzing the dynamic change law of the sliding angle with the rotation of the blade,it is found that under the normal operating conditions of the rotary burial blade roller,the change of the sliding angle can be ignored,which is approximately equal to the static sliding angle of the blade.In order to study the influence of the sliding cut angle on the straw slip,a straw sliding cut soil trough experiment was carried out.The test results verified the correctness of the straw burying conditions,and the range of the friction angle between the straw and the blade was 25°?30°.From the perspective of straw burial,it explains the rationality of the existing helical transverse blade static sliding angle parameters.In order to study the influence of the sliding angle on the operating power consumption,a simulation experiment of power consumption prediction was carried out.The test results show that the power consumption decreases with the increase of the static sliding angle of the helical transverse blade.Therefore,the static sliding angle should be larger under the condition of straw burying.(3)For the rotary burial blade roller composed of multiple blade types,the interaction mechanism between the blades is revealed by studying the disturbance of the internal blade types to the soil,which provides a theoretical basis for the subsequent optimal design of the blade roller for reducing the resistance and enhancing the quality.In the longitudinal direction,based on the circumferential blade distribution,establish the longitudinal cutting position equation of the helical transverse blade and the rotary blade to analyze the relative cutting position relationship between the two blades.The rotary burial blade roller is divided into a rotary blade part and a helical transverse blade part by the partial modeling method.Using the hysteresis angle as a variable,power consumption and relative wear as indicators,a simulation study of the influence of the longitudinal cutting position on the circumferential blade was carried out.The simulation results show that as the hysteresis angle increases,the power consumption of the rotary blade continues to decrease,the helical transverse blade continues to increase,and the rotary burial blade roller first reduces to a relatively stable state and then increases.In terms of relative wear,the rotary blade continues to decrease,the helical transverse blade continues to increase,and the rotary burial blade roller decreases first and then increases.The change law of relative wear is similar to power consumption,and the larger the power consumption,the higher the relative wear.When the hysteresis angle is set to make the longitudinal cutting position of the helical transverse blade coincide with the cuttingposition of the rotary blade,the power consumption of the rotary burial blade roller is at a relatively low level.In the horizontal direction,both the tangent part of the rotary blade and the helical transverse blade have a lateral push effect on the soil.Simulation experiments were carried out on the rotary buried blade roller,the rotary blade roller and the spiral blade roller in order to obtain the movement of soil particles and the axial force.According to the movement of soil particles,the axial flow effect of the soil in the cutting stage is weaker than that in the throwing stage,and the axial side thrust of the three types of blade rollers on the soil is from strong to weak,namely rotary blade roller,spiral blade roller,and rotary burial blade roller.And the coupling effect of the blade in the rotary burial blade roller makes the movement of the soil determined by helical transverse blade.According to the axial force of the blade roller,the rotation direction of the rotary blade and the helical transverse blade in the same segment of the rotary burial blade roller are opposite to conform to the design principle of mutual cancellation of axial forces.However,according to the sinusoidal fluctuation of the axial force dynamic characteristic curve,it is found that there is a phenomenon of large axial force fluctuations in the rotary burial blade roller.Aiming at the axial arrangement of rotary burial blade roller,a solution to the symmetrical arrangement of blades was proposed.(4)Based on the operating mechanism of the rotary burial blade roller and the interaction mechanism between the blades,as well as the problems in the preliminary test and demonstration,a herringbone rotary burial blade roller was designed.Aiming at the problem of high power consumption,the static cutting angle of the original helical transverse blade is reduced from 73° to 40°,and the blade width is increased from 25 mm to 35 mm.The increase in blade width is used to compensate for the loss of the thrown soil width due to the smaller cutting angle,and to maintain the original thrown soil coverage performance.In order to solve the problem of insufficient burying depth of straw,the original IT245 rotary blade matched with the helical transverse blade was replaced with the IT225 rotary blade.Under the condition of the same rotary tillage depth,it can increase the burying depth of straw by 20 mm.At the same time,under the condition that the original burying depth of straw remains unchanged,the unnecessary rotary tillage depth is reduced to reduce drag and power consumption.Aiming at the problems of large fluctuations in the axial force of the machine and insufficient operation stability,a herringbone blade arrangement and a matching cutter head assembly are designed.The rotary blades on both sides of the blade roller are equally spaced in the axial direction,and the drag reduction method is adopted to cut the soil successively in the same direction,which enhances the operation performance of the blade roller.Aiming at the problem of wheel rut and uncultivated area left by the blade roller after tillage,the working width of the blade roller is increased from 1850 mm to 2200 mm.The working width of the blade roller is larger than the distance between the outer edge of the rear wheel of the tractor,which can effectively increase the flatness of tillage and avoid the phenomenon of insufficient cultivation range of the blade roller.(5)In view of the difference between the designed herringbone rotary buried blade roller and the original blade roller,field comparison experiments were carried out,and the application of the herringbone rotary buried blade roller in paddy field and dry land and different straw fields was evaluated.The optimization inspection test of the helical transverse blade shows that when the static cutting angle is reduced from 73° to 40°,and the blade width is increased from25 mm to 35 mm,in the low-speed gear 1 at 540 rpm and 720 rpm gears,the straw buried rate increased by 0.16 and 0.78 percentage points,respectively,and the power consumption decreased by 5.68% and 8.44%;at low-speed gear 2 at 540 rpm and 720 rpm gears,the straw buried rate increased respectively 1.58 and 1.14 percentage points,power consumption decreased by 6.66% and 6.57% respectively.The comparison test of tool arrangement shows that compared with the staggered rotary burial blade roller,the overall stability of the herringbone rotary burial blade roller in the forward,vertical and width directions has been improved by 55.62%,31.24%,36.98%,and the power consumption has been reduced by 3.31%.The comparison test of rotary blade type matching shows that the power consumption of ?T225 blade roller increased by 2.55% and the straw buried rate increased by 5.56% compared with ?T245 blade roller when the tillage depth was the same;when the straw burial depth was the same,the power consumption of ?T225 blade roller decreased by 14.86% and the straw buried rate decreased by 1.25%.The multi-index comprehensive evaluation of the two blade rolls is carried out by the entropy weight method,and the index evaluation score of the IT225 blade roller is the highest 0.84.From the perspective of straw burying quality,the IT225 blade roller is superior to the IT245 blade roller in terms of uniformity,depth,and burying capacity.The field application research of the herringbone rotary burial blade roller shows that the knife roller has strong versatility and can cope with the operation of paddy field and dry land,flexible straw and hard straw. |
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