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.

Scuffing is one of the most typical damage forms in the gear transmission of agricultural machinery. The fast bursting speed and serious damage degree should be strictly avoided in the conditions of the low lubrication and extreme loading during the gear service. This study aims to improve the scuffing resistance load carrying performance in the transmission gears of agricultural machinery under severe lubrication, variable speed, and heavy-duty conditions. The surface coating strengthening was applied to the meshed tooth surface. A mathematical model was established for the relationship between the contact properties of coatings and gears, as well as the scuffing load capacity. The gear meshing, tribology, and thermodynamics were also utilized in this case. The finite element model of plane strain was selected to explore the influence of elastic modulus ratio between coating and substrate on the stress field distribution. Anti-scuffing gear coatings were achieved to clarify the effect of tooth surface frictional coefficient on oil film thickness and transient contact temperature, according to the calculation in ISO/TS 6336-22. Then, the carbon films were prepared by low-temperature plasma enhanced chemical vapor deposition technology. Surfaces of standard steel balls were coated with the tungsten containing ta-C and a-C:H coatings. Tribological properties of coating materials were evaluated using the four-ball method. A series of experiments of scuffing resistance were performed on the two coated gears in the FZG (Forschungsstelle für Zahnräder und Getriebesysteme) transmission test rig. The results showed that the carbon film friction pairs had the better running-in performance, compared with the uncoated components. The a-C:H coating presented the higher sp² C-C bond content than ta-C, resulting in a lower frictional coefficient. Also, the scuffing resistance capacity increased by 2 FZG loading stages in the ta-C coating, while at least 4 loading stages were found in the a-C:H coating one. In the process of engagement, the ta-C coating was peeled off, and then the peeled coating particles were pressed into, adhered to the contact surface, or discharged from the scratched surface, thus forming abrasive wear between the tooth surfaces, and finally the gear steel substrate was completely exposed. Furthermore, the failure mode was changed from abrasive wear to adhesive wear with the increase of frictional temperature. The surface material was subject to adhesive tearing. Moreover, both uncoated and ta-C coated tooth surfaces showed the significant competitive relationship between the thermal scuffing and micro pitting damage, which was mainly determined by the oil film thickness and contact temperature. In addition, the concave plastic deformation near the driving wheel pitch line was found on both surfaces. The a-C:H coating showed the conventional fatigue wear with the smooth and flat wear trace, where the tooth surface coating had the high integrity without outstanding damage. Theoretical analysis and experimental data were combined to enhance the gear scuffing resistance capacity. Although the frictional coefficient was low, the ta-C coating was more prone to the coating peeling and interface damage, due to the high elastic modulus ratio between coating and substrate. By contrast, a-C:H coating shared the relatively low elastic modulus ratio. The interface stress was smaller and more difficult to peeling, and the frictional coefficient was smaller, resulting in a relatively thicker oil film thickness and lower transient contact temperature on the tooth surface. The achievements demonstrated that the a-C:H coating exhibited the excellent scuffing resistance load carrying performance suitable for gear transmission. The finding can lay the foundation for the application of coating strengthening technology in the high-performance agricultural machinery gears, even the other transmission systems with harsh service conditions.

In response to address the issue of significant wear in the drive wheel groove within the rope wheel drive system of traction orchard transporters, resulting in traction slip failure, this study examines the wear resistance of the drive wheel in orchard transporters through the application of infiltration layer strengthening. Initially, the ANSYS software was utilized to investigate the relationship between the surface stress and strain of the drive wheel and its hardness. And the stress-strain law of the surface of the driving wheel rope slot was explored. The results showed that the maximum equivalent strain on the surface of the rope slot decreased with the increase of its hardness, which verifies the scientific basis of enhancing the wear resistance of the driving wheel by increasing the surface hardness of the rope slot. The thermal diffusion deposition (TD) technology was used to perform V and B coating strengthening treatment on the 45steel driving wheel. The structural characterization, mechanical properties, and friction and wear characteristics of the coating were compared and analyzed. Finally, the application performance of the strengthened driving wheel was tested using a transport machine simulation platform. The results showed that the thickness of the V and B layers is 20.9 and 97.3 μm respectively. Both are well bonded to the substrate, without obvious defects such as cracks or pores. Due to the formation of hard phases such as VC_x and Fe_xB in the coating, the hardness of the coating has been improved, with the hardness of the V and B coating reaching 22.08 and 13.45 GPa, respectively, which is 3-4 times higher than before treatment. Under dry friction, the surface friction coefficients of the V and B coating are 0.47 and 0.44, respectively, which are reduced by 19% and 24% compared to 45steel. And the average wear amount is reduced by 85% and 75% compared to 45steel, respectively. The friction and wear characteristics of the coating have been improved. The application performance test of the transport machine simulation bench showed that under dry friction, the average wear of the driving wheel after V and B coating treatment is reduced by 88% and 81% compared to 45steel respectively. Among them, the surface wear of the V coating driving wheel is the smallest, but the outer layer of the wire rope that matches it shows a phenomenon of wire breakage; Under oil lubrication friction, it decreased by 92% and 85% respectively compared to 45steel, and the wire rope showed no abnormalities. In summary, thermal diffusion V and B coating treatment can greatly improve the wear resistance of the driving wheel, in which the V coating has higher hardness and wear resistance, but in the application of real-time oil lubrication is required, more suitable for meeting the regular maintenance conditions of the drive wheel for strengthening. V and B coating’s wear resistance has been reduced, but can be used in dry friction, more suitable for the field and mountainous environments can not meet the lubrication of the drive wheel for strengthening. The results of this study can provide feasible technical solutions for improving the wear resistance of the driving wheels of the traction orchard conveyor.