Design And Experimental Of Seedbed Preparation System Of Rapeseed Substrate Seedling Transplanter

Rapeseed is an important oil-crop in China.Mechanized transplanting can alleviate the stubble contradiction in winter-type rapeseed-rice rotation area.In this paper,the present study endeavors to address the challenges associated with unstable ditching mechanisms and non-uniform soil coverage devices in regions dedicated to winter-type rapeseed cultivation,combine with the lack of research on seedling bed preparation system of rapeseed substrate block seedling transplanting machine,in order to meet the agronomic requirements of flat ditch bottom and flat surface of rapeseed substrate block seedling transplanting,a scheme of ditching,covering and pressing seedling bed preparation of rapeseed substrate block seedling transplanting machine is proposed.A seedbed preparation system for rapeseed substrate seedling transplanting machine(hereinafter refer to as seedbed preparation system)is developed.The design and optimization of critical elements of seedling bed preparation system are carried out,and the operation performance of key components of seedling bed preparation system of rapeseed substrate block seedling transplanting machine is compared and verified.Through a systematic comparative analysis of the research progress in seedbed preparation technology both domestically and internationally,a research scheme for a seedbed preparation system is proposed.The study primarily focused on investigating the key research areas and outcomes,which are summarized as follows:(1)The present study conducted tests and analyses to investigate the soil flow characteristics of a winter-type rapeseed planting area and the plant characteristics of rapeseed seedling substrate blocks during a suitable planting period.①Combined with the self-developed seedbed ditching device,the soil flow characteristics under different soil conditions and operating parameters were studied.The experimental findings indicate that as the operating speed increases,the width of soil accumulation widens while the height of accumulation decreases.There is a negative correlation between the operating speed and the soil accumulation height,whereas a positive correlation exists between the operating speed and the soil accumulation width.The correlation coefficient between the accumulation height and the operating speed is0.99972,while that between the soil accumulation width and the operating speed is 0.98857.As the working depth increased,both the width and height of soil accumulation demonstrated an increase.The width and height of soil accumulation were observed to be positively correlated with working depth,with a correlation coefficient of 0.99966 for the relationship between soil accumulation height and working depth.The correlation coefficient between soil accumulation width and working depth is 0.99930.The range of soil accumulation parameters is determined to be 27.31～50.12mm.The stacking width is 210.35～282.81mm.②Measurement with compatible substrate composition ratio cultivate rape matrix seedlings,different suitable planting period seedling height,seedling width,plant type cone angle and other parameters.The results show that the plant characteristic parameters of rape seedling substrate block met the normal distribution during the suitable planting period.The plant width and height characteristic parameters of seedling matrix block are positively correlate with time,and the plant width and plant height increase linearly with time.The correlation coefficient between seedling width and time is 0.9645,and the correlation coefficient between seedling height and time is 0.9967.The cone angle of plant type was negatively correlated with time,and the cone angle of plant type decreased linearly with time.The correlation coefficient between plant type and time is-0.9367.The range of seedling height is 72.68～128.98mm、seedling width range is 76.85～142.45mm、the cone angle of plant type ranged from 26.75°～40.25°.③The seedbed preparation system of rape substrate block seedling transplanter with the integrated technology of "ditching+covering soil+pressing" was developed.The composition structure and working principle of the seedbed ditching and preparation device,circular arc soil covering device and multi-effect pressing device are expounded.The main technical parameters and performance indexes of the seedbed preparation system of rape substrate block seedling transplanter were defined,the ditch in question possesses a width of 110mm and a depth is in excess of 40mm.Moreover,the thickness of the overlaying soil is in excess of 35mm,and its uniformity surpasses 90%,the variation coefficient of the covering soil thickness is more than 10%,and the seedling rate is more than 85%.(2)The key components of the seedbed preparation system were developed.The present study involved an analysis and determination of the structural parameters of the critical elements of the seedbed preparation system,as well as the primary factors that impact the system’s operational performance.①The seedbed ditching device which can construct wide seedling ditch,flat bottom and low disturbance was developed.Combine with the agronomic requirements,the kinematics and dynamics models of soil diversion,ditch extrusion and leveling ditch bottom stage of the seedbed ditching and preparation device are analyzed.The operational performance of the system is predominantly influenced by several key factors,namely the cutting-edge angle,the angle formed between the curve element line and the guide curve,the sliding angle,and the arc radius.The key structural parameters of the seedbed ditching device are analyzed and determined.According to the experimental measurements,the device exhibits a height of 120mm,an initial sliding angle of 25°,and an end sliding angle of 60°.Additionally,the cutting-edge curve attains a height of 164mm,while the front end of the furrow-like surface spans a range of 40-60mm.The results obtained from the study demonstrate that the system displays a maximum angle of 13° and a minimum angle of 0°between the curve element line and the guide curve.Moreover,the angle of the soil gap is determined to be 9.5°.②An arc-shaped soil covering device was designed to meet the requirements of soil uniformity of wide seedbed.By constructing the soil kinematics and dynamics model of the interaction between the circular soil cover and the soil,the principal factors that influenced the interaction between the circular soil cover and the soil include the angle between the tangent vector of a guiding curve and the horizontal axis,the slope of a linear function,and the working speed.The mathematical model of arc-shaped guide curve is established.Combine with the actual operation requirements and the characteristics of rapeseed seedlings in suitable planting period,the arc curve equations under different parameters are obtained.It is determined that the length of the guide curve and the inclination angle of the end of the guide curve are the key factors determining the parameters of the equation.③The key structural parameters of the multi-function pressing device of the rape substrate seedling transplanter ware determined.Based on the data of plant characteristics(seedling height,plant type cone angle)measured in the early stage,combine with the agronomic requirements of the multi-effect pressing device,the key structural parameters of the multi-effect pressing device are determined.The double-acting wheel has an inclination angle of 42°,a diameter of 200mm,a pressing wheel thickness of 40mm,and is installed at a distance of 160mm from the bottom.(3)Based on EDEM,the performance influence analysis and parameter optimization of the key components of the seedbed preparation system of rapeseed matrix seedling transplanting machine were carried out.①The optimal parameter combination test of the best working performance of the seedbed ditching device was carried out.In combination with simulation technology,a orthogonal combination simulation test was conducted,with the experimental factors being the working depth,forward speed,front width,and edge angle,while the experimental indexes included soil disturbance and the coefficient of variation of ditch width.The Design-Expert 8.0.6 software is used to analyze the constraint index.The orthogonal combination test results show that when the working depth is 41mm,the forward speed is 0.52m/s,the front end width is 40mm,and the cutting edge angle is 61°,the seedbed ditching device exhibited superior performance,with a soil disturbance of 13.01cm~2 and a coefficient of variation of ditch width of 8.52%under the optimal parameter combination.②The influence of key factors on the working performance of the arc-shaped soil cover was explored.Taking the traction resistance and soil uniformity of the arc-shaped overburden as the test indexes,an analysis was conducted on the impact of the inclination angle of the straight line,additionally,both the inclination angle of the guide curve end and working speed were taken into consideration,on the corresponding performance indices.Results from the tests indicated that the traction resistance rises as the forward speed increases,as the forward speed increases,there is a corresponding increase in the interaction force between the soil surface and the soil located on the side of the ditch.and the traction resistance increases.The traction resistance of the soil covering device decreases slowly with the increase of the inclination angle of the straight line,and the uniformity of the soil covering increases first and then fluctuates slightly with the increase of the inclination angle of the straight line.As the end inclination angle increases,the traction resistance exhibits fluctuation,while the overall variability remains stable.The uniformity of the overburden soil decreases step by step with the increase of the end inclination angle.It is clear that the suitable range of each factor is 0°～15°,the forward speed is 0.5～0.7m/s,and the straight line inclination angle is 65°～75°.(5)The field experiment was carried out to verify the performance of the seedling bed preparation system of the rapeseed matrix seedling transplanting machine,and the optimal parameter combination of the arc-shaped casing was studied.①The comparative test of seedbed ditching device and ship opener was carried out.The seedling rate of the transplaner with the seedling bed trenching device is 91.68%,and the actual seedling rate of the transplanting unit equipped with the boat-type trencher is 89.59%.Compare with the boat-type trencher,the seedling rate of the seedling bed trenching device increased by 2.09%.The compactness of the seedling ditch constructed by the transplanting unit of the seedbed ditching device is 79.927kPa,and the compactness of the seedling ditch constructed by the transplanting unit of the ship opener is 62.119kPa.Compared with the ship opener,the compactness of the seedling ditch of the seedbed ditching device increased by 21.37%.The coefficient of variation of the ditch width of the seedbed ditching device is 9.58%,and the soil disturbance is 14.79cm~2.The coefficient of variation of the ditch width of the ship opener is 11.05%,and the soil disturbance is 18.69cm~2.Compared with the ship opener,the coefficient of variation of ditch width of the seedbed opener was reduced by 13.3%and the soil disturbance was reduced by 28.3%.②The optimal parameter combination of arc-shaped soil covering device for rape matrix seedling transplanting machine was determined.Combine with the transplanting unit test platform,the seedling rate and soil uniformity are taken as the test indexes,and the forward speed,the variables being tested are the inclination angle of the straight line and the inclination angle at the end point.The Design-Expert 8.0.6 software is utilized to analyze the constraint index.The optimal parameter combination is:the forward speed is 0.5m/s,the straight line inclination angle is 65°,and the final inclination angle measures 15°.With the optimal parameter combination in place,the following outcomes were observed that the bench test verified that the uniformity of the overlying soil is 86.52%and the seedling rate is 90.27%.③The performance verification test of the key parts of the seedbed preparation system was carried out.The seedling rate of the transplanting unit with the seedling bed ditching and preparation device is 91.42%,and the seedling rate of the transplanting unit with the seedling bed ditching and preparation device+circular soil covering device is 90.05%,which is 1.37%lower than that of the seedling bed ditching and preparation device.The seedling rate of the transplanting unit installed with the seedbed ditching and preparation device+arc-type soil covering device+double-acting pressing device is 87.36%,the soil covering uniformity is 89.32%,the soil covering thickness is 37.28mm,and the soil covering thickness variation coefficient is 8.76%.The seedling rate of the transplanting unit installed with the seedbed ditching and preparation device+arc-type soil covering device is 90.05%,the soil covering uniformity is 86.39%,the soil covering thickness was 35.49mm,and the soil covering thickness variation coefficient is 10.12%.Compare with the combination of seedbed ditching and preparation device+arc-shaped soil covering device,the seedling rate of seedbed ditching and preparation device+arc-shaped soil covering device+double-acting pressing device decreased by 2.69%,the degree of uniformity of soil covering increased by 2.93%,the depth of soil covering increased by 1.79mm,and the coefficient of variation of soil covering thickness reduced by 1.36%.④The performance of seedbed preparation system of rapeseed substrate seedling transplanting machine was verified.The seedling rate of the transplanting machine equipped with a seedbed preparation system is 86.74%,the uniformity of covering soil is 89.21%,the depth of covering soil is 37.72mm,and the coefficient of variation of covering soil thickness is 8.95%,all of which satisfied the requirements for rapeseed transplanting.