| China’s hilly and mountainous areas are vast,the cultivated land area is large,and the amount of cultivated land in the hilly mountainous area is about two-thirds of the total cultivated land in the country,but ordinary agricultural tractors are difficult to meet the complex slope operation environment.The operating performance of hilly mountain tractors is mainly manifested in good slope adaptability,not easy to tip over,not easy to slide,good passability and stability,and good obstacle crossing performance.At present,the research of hilly mountain tractors in China is still in its infancy,various technologies are still in the theoretical stage,and most of the hilly mountain tractors are still in the trial production stage.With the increasing attention paid to the development of agriculture in mountainous areas in China,the importance of agricultural machinery in hilly and mountainous areas has become more and more prominent,and the demand for agricultural machinery in hilly and mountainous areas has become increasingly large.The development of hilly mountain machinery with excellent performance is of great significance to improving the efficiency of agricultural work in hilly and mountainous areas.Due to the poor slope stability of ordinary wheeled tractors,the high slip rate,and the low economic benefits of agricultural operations in hilly mountainous areas,thesis paper studies the 504 variable diameter wheeled hilly mountain tractor and completes the design of the 504 variable diameter wheeled hilly mountain tractor variable diameter wheel.The main findings of the thesis are as follows:(1)Mechanism design results:The mathematical model of kinematic analysis and Simulink model were established,and the results showed that: when the hydraulic cylinder stroke is 125 mm,the minimum radius of the reducer wheel is 340 mm,the maximum radius is 475 mm,the wheel achieves a wheel diameter change of 0.7-1 times,which meets the variation requirements in actual work,and the angle between the connecting rod and the reducer wheel axis ranges between 20 degrees and 65 degrees,avoiding the friction angle of 8.5 degrees,and the mechanism does not have self-locking.Kinematic simulation results also show that the diameter change action of the wheel is a fast response and the diameter change action is gentle.The mathematical model of dynamic analysis and Simulink model were established,and the results showed that the hydraulic cylinder was subjected to an axial force of up to 4800 N when the wheel was just unfolded and the rim was in contact with the ground,the use of the hydraulic cylinder was within the safe range,and the telescopic spoke tube was subjected to a positive pressure of up to 1100 N.(2)Analysis and research results of slope stability of variable diameter wheel hilly mountain tractor:Establish a mathematical model of the slope stability of the 504 reducer wheeled hilly mountain tractor,use ADAMS software to establish a stability simulation simulation platform,analyze its stability performance on different angles of slope,use MATLAB software to analyze its ramp drive performance,and finally conclude: the ultimate inclination angle of the transverse ramp of the 1.504 variable-diameter wheeled hilly mountain tractor is 46.56°,and the lateral tilt stability is good;the longitudinal ramp limit of the 2.504 variable-diameter wheeled hilly mountain tractor is 49.21°,The longitudinal ramp tilt stability is good;the ramp slip rate of the 3.504 variable diameter wheeled hilly mountain tractor is 8%,and the slope stability and drive are good.The variable diameter wheel hill tractor has good ramp anti-rolling,anti-slip performance and good ramp driving performance,so it is more practical and economical.(3)The results of the finite element analysis of key working components:The 3D model of the key components is established by CATIA software,and imported into ANSYS for finite element analysis,and the final result is: 1.ANSYS finite element analysis result of the telescopic spoke tube: The maximum displacement of the telescopic spoke tube appears at the top of the spoke under the action of the tangential force of 2650 N,the maximum displacement is 0.021 mm,and the maximum stress occurs at the socket of the two spokes,which is 25.32 MPa,which structurally meets the needs of the design 2.Under the action of the vertical force of 2500 N,the maximum deformation of the connecting rod is 0.12 mm,the deformation amount is much less than 1mm,and the maximum stress is 43.1MPa,which meets the needs of structural design.In the later stage,the strength of the parts can be improved by thickening the telescopic spoke tube and thickening the connecting rod. |
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