| The effect of land preparation before sowing has an important effect on the yield of wheat.The traditional land preparation process of wheat before sowing includes deep loosening,rotary tillage,fertilization,levelling,and so on.Most of these processes are carried out by a tractor driven by a single working machine.The working procedure is complicated,time-consuming and laborious,which damages the soil structure and affects the quality of soil preparation.Therefore,according to the agricultural requirements of wheat planting in Hebei area,this paper designs and optimizes the multi-function combined operation machine of deep loosening,rotary tillage,layered fertilization and suppression.The main contents of the study are as follows:Optimization design of the whole machine structure of the joint operation machine.According to the agronomic requirements,the overall scheme design of the joint land preparation machine was compared and determined.The whole machine was composed of deep loosening,rotary tillage,layered fertilization and suppression.The layout of deep spatula is double row front interlaced arrangement,the structure of deep loose shovel shank is optimized,the uniform fertilization mechanism and the anti blocking mechanism of dredging fertilizer are designed,and the suppression mechanism adopts the roller type of sloping soil crushing.Structure design and simulation analysis of layered fertilization device.In order to solve the problems of excessive concentration of fertilizer in deep layer and easy clogging of fertilizer mouth in the spade operation of combined operation machine,a layered fertilization device was optimized and designed.The simulation model of fertilizer particle and layered fertilization device was established by using discrete element method.Three factors,such as inclination angleαof different fertilization mechanism,length of fertilizer slice L and vibration frequency f of fertilizer cleaning unit,were simulated and analyzed.The results show that when the installation angleαis 30°,the working length of the middle layer L1 is 14 mm,the working length of the lower layer L2 is 29 mm,and the vibration frequency f of the fertilizer cleaning device is 1 Hz.The rate of fertilizer application was 23.3%,23.8%,31.2%and 21.7%,respectively,and the ratio of fertilization was the most close to the agronomic requirement of wheat growth.Compared with the simulation test,the relative error of indoor bench test and field experiment is less than 5%,which indicates that the design of delamination fertilizer applicator is reasonable.Optimization design and simulation analysis of spade structure.In order to solve the problems of high depth resistance and high energy consumption,the depth ratios of different deep loosening shanks(0.70,0.80,0.90,0.93common deep loosening shovel handle,1.00)were studied.The soil trough models were established by using discrete element method and EDEM software.Virtual simulation of tillage resistance of deep spatula with different depth ratio is carried out.The results show that when the depth ratio of the deep loose shovel is 0.80,the resistance of the deep loosening shovel is the least.The results of soil trough test and field test show that the resistance of the shovel with the depth ratio of0.80 is 3.18%and 6.53%lower than that of the national standard.The experimental results are close to the simulation results,and the numerical error is less than 10%.The results of field performance test showed that the depth of deep ploughing,the depth of rotary tillage,the width of tillage and the coverage rate of vegetation all met the requirements of the index,the stability coefficient of deep sown depth and the coefficient of stability of rotary tillage were all in line with the requirements.The coefficient of stability of tillage width and vegetation coverage were 91.69%,92.05%,95.19%and81.6%,respectively.After suppression,the surface was relatively flat,and the average soil firmness in 0~120cm plough layer was within the range of 1~4kg/cm~2.It has met the requirement of land preparation before wheat sowing.After 15 days of sowing,two hundred and fifty thousand wheat seedlings per mu were measured,and the sowing time of the tested wheat was higher than that of the normal wheat.When the planting time was delayed by 10 days,the tiller number of wheat was 2~3,which had no obvious change compared with that of normal wheat. |
