Experimental Study On Special-Shaped Cavity Profiling Depth Limiting Wheel

Corn is the largest food crop in China,which has an important strategic position in ensuring China ’s food security.Jilin Province,as a major corn planting province,with the promotion of conservation tillage technology,the number of corn no-till planters in Jilin Province has increased year by year.The profiling depth limiting wheel is one of the important components of the corn no-tillage planter.,the main function of the profiling depth limiting wheel is to work with the opener to construct a seed furrow with a certain depth and structure.The internal structure of the traditional profiling depth limiting wheel is mostly solid or symmetrical hollow structure,and the rebound performance is not good.Therefore,it is easy to adhere to the soil during operation,resulting in a decrease in the uniformity of trenching depth.In addition,the contour of the traditional profiling depth limiting wheel is flat,which is easy to compact the groove wall and is not conducive to the growth of seed roots.Aiming at the problems of large amount of soil adhesion,poor consistency of ditching depth and poor construction of seed furrow in the operation of traditional profiling depth limiting wheel,this paper improves and optimizes the internal structure and external contour of profiling depth limiting wheel,and then designs a special-shaped cavity profiling depth limiting wheel with good desorption viscosity reduction performance and seed furrow construction performance.The main research contents are as follows.:(1)According to the shortcomings of the traditional profiling depth limiting wheel(solid profiling depth limiting wheel,symmetrical cavity profiling depth limiting wheel),a new type of profiled cavity profiling depth limiting wheel is designed.Based on the theoretical analysis of the profiling depth limiting wheel,the installation position,width,diameter and material parameters of the profiling depth limiting wheel are determined.In view of the shortcomings of the existing profiling depth limiting wheel,the structural outline and internal cavity of the profiling depth limiting wheel are improved.The three-dimensional software CATIA is used to model the new special-shaped cavity profiling depth limiting wheel.(2)The ANSYS software is used to simulate and compare the profiling depth limiting wheel,and the deformation and stress distribution of the profiling depth limiting wheel with different external contours and internal structures are analyzed.Compared with the traditional profiling depth limiting wheel,the special-shaped cavity structure of the new profiling depth limiting wheel under the same pressure can weaken the stress concentration problem and reduce the stress concentration phenomenon while the deformation change is small,and will not cause excessive compaction.The advantages of designing special-shaped cavity profiling depth limiting wheel are determined.This structure not only improves the stability of sowing depth,but also facilitates the growth and development of root system.(3)The ANSYS software is used to simulate and compare the profiling depth limiting wheel,and the deformation and stress distribution of the profiling depth limiting wheel with different external contours and internal structures are analyzed.Compared with the traditional profiling wheel,the special-shaped cavity structure of the new profiling wheel can weaken the stress concentration problem and reduce the stress concentration phenomenon while the deformation change is small,and will not cause excessive compaction.This structure not only improves the stability of sowing depth,but also facilitates the growth and development of roots.(4)In order to test the actual operation effect of the special-shaped cavity profiling depth limiting wheel and determine the optimal operation parameter combination of the seeder,a field experiment was carried out.In the experiment,the operating speed,the underground pressure and the sowing depth were selected as the experimental factors.The three-factor and three-level test was designed according to the Box-Behnken Design(BBD)in the Design-Expert 8.0software,and the soil adhesion amount and the coefficient of variation of the sowing depth of the seeder were used as the experimental indexes.The test results show that the primary and secondary order affecting the amount of soil adhesion of the profiling depth limiting wheel is the underground pressure,operation speed and sowing depth.The primary and secondary order affecting the coefficient of variation of sowing depth is the working speed,sowing depth and underground pressure.According to the test results,it is predicted that when the underground pressure of the seeder is 844 N,the operating speed of the seeder is 8km / h,and the sowing depth is 65 mm,the seeder has the best operation effect.The soil adhesion mass of the special-shaped cavity profiling depth limiting wheel is 118.56 g,and the coefficient of variation of sowing depth is 5.01 %.The relative error between the results of the verification test and the predicted results is 4.3 % and 14.8 %,indicating that the predicted test results are credible.