Influence and optimization of surface coating thickness on the power consumption of rotary blades

Surface hard coating has been widely used to enhance the wear resistance of the rotary blade. The cutting-edge thickness can also increase to change the mass distribution during tillage, leading to a great variation in the operation torque and power dissipation. This work aims to explore the influence of the surface coating thickness on the power consumption of rotary blades using the discrete element method (DEM). Some parameters were also calibrated to determine the susceptible position of the rotary blade after simulation. The coatings were then deposited with the 1, 1.5, and 2 mm thickness using plasma surfacing. The power consumption was also tested in the field. The results indicated that the susceptible position of the rotary blade was at the tangent edge and bending part. The torque of rotary blades with coating thicknesses of 1, 1.5, and 2 mm increased by 7.69%, 13.03%, and 17.86%, respectively, compared with the uncoated ones. The field test showed that the average power consumption of the coated rotary blades increased from 12.91 to 14.51 kW, 15.15, and 16.37 kW with the coating thickness from 0 mm to 1, 1.5, and 2 mm, respectively, which increased by 12.4%, 17.3%, and 26.8%, respectively. The test and the simulation were consistent in the torque and power consumption of rotary tillage. The range of relative error between the simulation and experiments was 0.17%-6.77%, which verified the accuracy of the DEM simulation. The power consumption composition of rotary tillage was determined after optimization. The cutting soil and throwing soil contributed the most to the power consumption of the rotary blade. The force on the rotary blade was also regarded as the three-dimensional force. The three-dimensional tillage resistance was detected after DEM simulation, according to the torque of the rotary blade. Among them, the coating shared the greatest influence on the vertical resistance. As such, three reasons were attributed to the power consumption of rotary blades. 1) The coating increased the thickness of the blade edge, leading to the increase of the contact area and vertical resistance during tillage. 2) The coating also caused the position of the center of mass of the rotary blade. 3) The tracking of soil movement depended mainly on the discontinuous protrusion of the coating on the surface of the rotary blade and the adhesion of soil, leading to the increase of resistance. Three factors then increased the power consumption of the rotary blade. The wear rate of the coated blade was calculated, according to the mass loss. Thus, the relationship between cultivated area and coating thickness was also established after calculation. The cost and power consumption were considered to evaluate the coating wear performance. The optimal thickness of hard coating rotary blade was determined to be 1.25 mm. The service life of the blade was prolonged to 1.5 times with a small power consumption increment of 12.29%. Cost analysis was also combined with the variation of the coating thickness of the rotary blade on the tillage area and power consumption. An optimal thickness was selected to promote the application of the hard coating on the rotary blade. The findings can also provide a profound understanding of the relationship between the coating and the power dissipation of the rotary blade.