Design and test of sawtooth fertilizer block crushing blade of organic fertilizer deep applicator

Abstract: This paper presents the design of a device for crushing caked fertilizer for the deep applicator of organic fertilizer. It is a kind of toothed crushing blade. The process of designing this device combines the simulation test and the physical test. In the EDEM software, Hertz-Mindlin contact model and the bonding model were selected to establish the bonding model of the caked fertilizer crushing blade. To replicate the mechanical properties of the actual blade in the bonding model of the caked fertilizer crushing blade, a uniaxial compression test was carried out to calibrate the bonding parameters, and the regression equation of maximum force, displacement and bonding parameters of caked fertilizer were obtained. Aiming at the maximum force and displacement value obtained from the uniaxial compression physical test, the multi-objective genetic algorithm available in the optimization toolbox of MATLAB software was used to optimize the bonding parameter, and the optimal combination obtained was that the unit normal stiffness was 5.80×108 N/m3, the unishear stiffness was 3.50×108 N/m3, the critical normal stress was 3.29 MPa, the critical shear stress was 2.92 MPa, and the bonding radius was 1.26 mm. The simulation model of a single caked fertilizer crushing blade was established, through the single factor simulation test, the influences of the rotating speed, sliding cutting angle, edge angle, tooth width and tooth height of the crushing blade at the maximum value of three-way resistance, resultant force and the crushing rate of caked fertilizer were analyzed. Taking the ratio of the maximum resistance of the crushing blade to the crushing rate as the evaluation index, the uniform design simulation test was carried out. Regression analysis was carried out on the test data, and the regression equation between the evaluation index and the crushing blade parameters was obtained. The genetic algorithm in MATLAB software optimization toolbox was used to obtain the optimal combination of the crushing blade parameters. The optimal combination of the crushing blade parameters was that the rotating speed of the crushing blade was 300 r/min, the sliding cutting angle was 8°, the edge angle was 50°, the tooth width was 3.9 mm and the tooth height was 2 mm. The simulation verification test was carried out based on the optimization results. The results showed that the maximum resistance to the blade was 74.59 N, the crushing rate was 25.63%, and the ratio of the maximum resistance of the crushing blade to the crushing rate was 291.03 N. According to the optimized results, the fertilizer crushing blade was processed, and the physical test was carried out on the fertilizer crushing device powered by BMM-50 hydraulic motor. At the same time, the oil inlet pressure of the motor was measured by the oil pressure sensor to evaluate the energy consumption. After crushing, the particle size distribution was determined to evaluate the crushing quality. The results showed that the average oil pressure for crushing was less than 2.44 MPa, and the average energy consumption required for crushing was less than 480 W, the particle size of the fertilizer was less than 20 mm. The blade has low energy consumption and high crushing rate and can be used for the caked fertilizer crushing operation.