Design And Experimental Study Of Lightweight High Strength Omnidirectional Pressing Device

As the final step in the seeding operation,soil compaction is a key link in the conservation tillage process and its quality has a significant positive effect on improving soil water content and porosity,as well as increasing crop emergence.However,as a typical clay loam soil texture of the northeast black soil area,soybean planting pattern is generally soybean ridge planting pattern of multiple rows,if the use of traditional compaction roller for compaction operations,there is a crop after sowing the ridge side of the problem of lack of compaction.When using traditional ridge side press device for suppressing,problems such as high traction resistance,high power consumption and poor profiling ability are encountered.This paper aims to design a lightweight,high-strength,omnidirectional pressing devices suitable for local agronomic requirements through structural design,simulation analysis,material optimisation design and theoretical analysis based on the agronomic pattern and requirements of ridge cropping in the north-east.Use of carbon fibre composites instead of the traditional 65 Mn material reduces the weight of the press device and improves material performance.In addition to ensuring the volumetric density of the soil on the ridge after the operation,it achieves complete suppression on the ridge and on the side of the ridge,improves the quality of the suppression operation and creates better temperature and humidity conditions for the crop to grow.A summary of the key findings of this study can be found below:1)The main parameters of the suppression structure are determined by theoretical analysis.According to the agronomic requirements of the Northeast ridge planting pattern,the upper press plate width adjustment range,the upper press plate outlet width adjustment range,the upper press plate length adjustment range and the relevant parameters of the side press plate were determined.The entrance width is adjustable in the range 270～370mm,the outlet width is adjustable in the range 240～300mm,the upper press plate length is 500 mm and the side presses are adjustable in the range 140～240mm.The shape of the side press plate is designed as two circles with a large front end and a small rear end,where the diameter of the large semicircle is170 mm and the diameter of the small semicircle is 130 mm,the length of the side press plate is500 mm and the lateral inclination angle of the ridge is 40°～44° according to the natural repose angle of the ground and other relevant parameters.2)Optimisation of the materials used for the side and upper press plates of the omnidirectional pressing devices.A carbon fibre composite laminate was chosen as the reinforcement material for the press device in place of the traditional 65 Mn steel plate.Using modified epoxy resin as the base material,the carbon fibre composite laminate is manufactured using a hot pressing process,and the carbon fibre composite laminate is water jet cut to a predetermined shape to form the side and top presses of the pressing device.3)A coupled DEM-MBD simulation test was carried out on the pressing device.The purpose of the simulation tests is as follows:(1)To determine whether a composite pressing device can significantly reduce the traction resistance of a pressing device compared to conventional 65 Mn materials.(2)The influence of the core parameter(spring stiffness)of the omnidirectional pressing device on the soil suppression strength at the top and side of the ridge at different operating speeds is shown.(3)Solve for the spring stiffness and operating speed of the omnidirectional pressing device at optimum soil compaction intensity above and to the side of the ridge.The results of the DEM-MBD coupled simulation tests show that the traction resistance of the composite omnidirectional pressing device is 38.76% lower than that of the conventional metal omnidirectional pressing device at the same spring stiffness and operating speed.(4)The effect of spring stiffness and operating speed on soil firmness is obtained for two different materials of the omnidirectional pressing device and the optimum solution is found from these.Finally,the optimum working parameters for achieving the soil suppression required for soybean growth in the north-eastern black soil region were obtained: spring stiffness of 3850 N/mm and working speed of 6 km/h.4)Based on the results of the simulation tests,field trials were carried out with a composite omnidirectional pressing device compared to a conventional press roller.The field experiment tested the soil firmness of the composite omnidirectional pressing device at the top and side of the ridge at the simulated optimum operating speed and spring stiffness,and measured soil moisture content after 15 days of suppression and crop emergence after 22 days of suppression.The results of field experiments have shown that soil moisture content and crop emergence rates on and to the side of the ridge are better after operation of the composite omnidirectional pressing device than those of conventional press rollers.This indicates that the soil indicators are more conducive to crop growth and that crop emergence is significantly higher after omnidirectional pressing device than with conventional press rollers.For the typical clay loam soil texture of the north-east black soil region,this paper uses a new carbon fibre composite material to design a lightweight and high-strength omnidirectional pressing device.Compared with conventional press rollers,the omnidirectional pressing device allows the soil to be suppressed on the ridge side and is more suitable for the double row(multi-row)soybean planting pattern on the north-east ridge.Compared to conventional composite omnidirectional pressing devices,carbon fibre composite omnidirectional pressing devices have low traction resistance and low power consumption.The results show that the soil-related indicators are more suitable for soybean growth after omnidirectional suppression,which provides technical support and methods for the future application of composite materials in agricultural machinery,the development of lightweight and high-strength agricultural machinery,and the simulation and development of omnidirectional pressing devices.