| The Yangtze River Basin is the main winter rapeseed production region in China.The planting mode is mainly rice-oil or rice-oil-oil-water paddle wheels with two crops a year or three crops a year.The stubble in the Yangtze River Basin is contradictory,and mechanized transplantation is one of the main methods of rape cultivation in most regions.Aiming at the problems of the complex structure of the seedling detach device and seedling pick-up device of the traditional transplanter,the poor adaptability to rapeseed matrix seedlings,and the low degree of motion matching between the components,the key devices of the rapeseed substrate seedling transplanter have been carried out to design.Combined with the domestic and foreign transplantation technology and device research foundation,the structural design of the seedling detach device and the seedling pick-up device of rapeseed substrate seedling transplanter have been carried out,the optimization of the working parameters of detach and pick-up process has been carried out.The field experiment of the rapeseed substrate seedling transplanter has been carried out,which verified the working performance of the transplanter.The research results provide a certain reference for the design and research of rapeseed substrate seedling transplanter and its key components.The main research contents and results are as follows:(1)Self-made Rapeseed substrate seedling was made by oneself,and the average water content and the average seedling mass of the seedling block were measured.By measuring the morphological characteristics of rapeseed seedling block in the suitable planting period,the shape dimensions such as seedling height,seedling width,and stem diameter were determined,which provided a basis for the design of key components for seedling detach device and seedling pick-up device of the rapeseed substrate seedling transplanter.Based on systematic comparative research on mechanized transplanting technology and equipment in this field,a rapeseed substrate seedling transplanter was developed,and the overall process plan of seedling delivery,seedling detach,seedling pick-up,planting simultaneous ditching,and soil cover was proposed,and the overall structural parameters of the rapeseed substrate seedling transplanter was analyzed and determined.The structure composition,working principle and working process of rapeseed substrate seedling transplanter were expounded,and its overall working parameters and performance indexes were determined.(2)The inclined conveying clamping and separating type seedling detach device of rapeseed substrate seedling transplanter was designed,the analysis of seedling detach process and seedling detach requirements were carried out,and the main structural parameters of the seedling detach device was determined.A mechanical model of substrate seedling at each stage of seeding detach process was constructed,and mechanical analysis was performed on substrate seedling.Combined with the experiment of friction characteristics of seedling block,the main factors affecting the stability of substrate seedling were explored.The analysis showed that when the friction characteristics of the seedling block were constant,the greater the holding force of the seedling detach,the better the stability of the seedling detach.When the inclination angle of the synchronous belt was 30°,the clamping force of the seedling detach was greater than 0.8N,the corresponding working air pressure of the seedling cylinder was not less than 0.5MPa,and the length of the substrate seedling loading platform was 85 mm,which can meet the need for seedling block no toppling-over,offsetting in seedling detach progress and the need for effective seedling stability for seedling and clamping.(3)The traditional method of seedling pick-up was contrasted and analyzed,the pneumatic reciprocating clamp type seedling pick-up device of rapeseed substrate seedling transplanter was designed based on the principle of pneumatic control,the structural composition and seedling pick-up process were explained,and the pneumatic system design was completed.A dynamic model of the substrate seedling in seedling pick-up progress was constructed,and the conclusion of the clamping force required for the substrate seedling to take off was related to the frictional characteristics of the seedlings was found.The greater the friction coefficient between the substrate seedling and the seedlings pickup splint,the smaller the gripping force needed for substrate seedling in the pick-up progress.The experiment of the compressive characteristics of substrate seedling was carried out,the analysis showed that the matrix loss rate decreased with the increase of the compressive strength of the seedlings.When the clamping force of the seedlings pick-up was less than 80 N and the clamping amount was less than 5mm,it was beneficial to reduce the matrix loss.The parameter analysis of the end effector of the seedling pick-up device was completed.When the cylinder diameter of the seedling removal cylinder was 20 mm,the spacing of seedling pick-up splint and clamping force of the seedling seedling pick-up device could meet the needs of the seedling pick-up.(4)The structure parameters of the pneumatic reciprocating clamping type seedling pick-up device of the rapeseed substrate seedling transplanter and the analysis of the seedling trajectory were analyzed and determined,mainly include:1)According to the complex non-linear equations formed by the mathematical model of the seedling pick-up device,combined with the static trajectory of the seedling pick-up arm,with the goal of reducing the horizontal distance and height of the seedling pick-up trajectory,the optimal structural parameter combination of the seedling pick-up device based on the quasi-Newton method was optimized as: The length of the driving rod was 75.10 mm,the length of the seedling pick-up arm was 335.26 mm,the length of the driven rod was 100.42 mm,and the length of the frame was 171.32 mm.Under this parameter combination,the theoretical horizontal distance of the seedling pick-up track was 175.28 mm,and the actual height of the seedling taking pick-up was 30.40 mm,which met the expected optimization goal.2)A parametric model of the seedling pick-up device was established based on ADAMS,the simulated seedling pick-up trajectory was analyzed under the optimal structural parameter combination,and the actual seedling pick-up trajectory was extracted using high-speed photography technology,the rationality of the design of the seedling removal device was verified by comparison.The analysis showed that the horizontal distance of the actual seedling pick-up trajectory was 175.28 mm and the actual height of the seedling pick-up trajectory was 30.40 mm.The error value between the experiment value and the simulation value was less than 3%.It showed that the design of the optimized seedling pick-up device was reasonable and can meet the trajectory requirements of rapeseed seedling pick-up device.(5)The influence of the working parameters of seedling detach and seedling pick-up effect was systematically analyzed,the value range of each influencing factor and the corresponding evaluation index were determined,and the optimal working parameter combination was optimized as: synchronous belt line speed was 76.5mm/s,active rod angular velocity was 1.47rad/s and cylinder air pressure was 0.74 MPa.The combined verification experiment of this parameter combination showed that the success rate of simultaneous seedling detach and pick-up was 93.33%,the seedling removal rate was 2.86%,the matrix loss rate was 3.75%,and the comprehensive score of the seedling detach and pick-up effect was 94.7,The error from the theoretical value was less than 3%,which indicated that the effect of separating seedlings detach and pick-up was reliable.(6)According to the overall process plan of the transplanter,the inclined conveying and clamping and separating seedling detach device,the pneumatic reciprocating clamping and seedling pick-up device,the soil working parts,the pneumatic drive and control system,and the whole machine power transmission system were trial-produced and the rape substrate seedling transplanter was trialed and manufactured.Under this condition that the soil water content was 18.7%,the soil solidity was 1956.4KPa,the field performance experiment of the rapeseed substrate seedling transplanter was carried out.The results of testing the relevant performance parameters showed that the success rate of simultaneous seedling detach and pick-up was 90.4%,the qualified rate of planting depth was 81.6%,and the qualified rate of uprightness was 75.2%,which basically met the requirements of rapeseed planting. |
PDF Full Text Request