根茎类作物单摆铲栅收获装置渐变抛掷特性

Gradient throwing characteristics of oscillating slat shovel for rhizome crop harvesters

单摆铲栅是基于变幅变向振动技术研发的铲栅一体收获装置。为明确单摆铲栅工作特性及抛掷分离作业机理,该研究在运动学及动力学分析基础上建立了铲栅工作面抛掷系数解析方程,铲栅工作面各点抛掷系数随工作长度逐渐增大,铲栅具有明显的渐变抛掷特性和较强的抛掷能力,分离区抛掷系数达9.98~19.72;建立了单摆铲栅EDEM-MBD耦合仿真模型,以振幅、振动频率、前进速度为因素开展单因素仿真试验,试验结果表明:受工作面抛掷特性及土壤粘塑性影响,牵引阻力、驱动转矩具有明显的强弱周期,在强周期内:单摆铲栅与土壤互作力较大,分离间距最大值发生在该周期切削行程终点时刻分离区中点处;振幅为7~11 mm时,牵引阻力均值约1580.93~2019.9 N、最大驱动转矩约224.04~322.11Ν·m、最大分离间距约59.58~98.3 mm;振动频率为6.67~10.67 Hz时,牵引阻力均值约1416.43~1866.38 N、最大驱动转矩约315.28~364.19Ν·m、最大分离间距约78.43~94.67 mm;前进速度为0.2~0.4 m/s时,牵引阻力均值约1429.43~2110.48 N、最大驱动转矩约241.27~387.78Ν·m、最大分离间距约62.5~102.5 mm。甘草收获试验结果表明:甘草收获机牵引阻力32.17 kN、驱动转矩802.02Ν·m、挖掘深度468 mm时,收净率为96.42%,单摆铲栅作业过程流畅有序,渐变抛掷作用明显,根茎土壤分离效果良好。该研究结果可为根茎作物特别是深根茎作物节能高效收获提供参考。

An oscillating slat shovel has presented a promising application potential in the energy-saving and efficient harvesting of deep rhizome crops.This new type of shovel slat integrated harvesting device was developed by gradient amplitude and gradient vibration technology.This study aims to clarify the working characteristics of oscillating slat shovels and the mechanism of throwing separation.The throwing coefficient was selected to characterize the throwing separation ability of the slat shovel work-plane.A motion analysis was made to calculate the swing acceleration of the slat shovel work-plane.An analytical equation of the throwing coefficient was then established to combine with the working process,the periodic variation of the throwing coefficient,and the influence of parameters,including the amplitude,vibration frequency,and working length.The results showed that the throwing coefficient gradually increased at each point of the slat shovel work-plane,indicating outstanding gradient throwing characteristics and strong throwing ability.The maximum throwing coefficient was 9.98-19.72 in the separation area.After that,an investigation was made to determine the influence of the structure and working parameters of the oscillating slat shovel on the soil throwing separation performance.The EDEM-MBD coupling simulation model of the single pendulum shovel gate was established to simplify the structural model and the interaction between the rhizome,soil,and working components,where the indicators were set as the traction resistance,driving torque,the maximum separation distance between the soil and the slat(separation distance),and the ratio of the separated soil quality of each functional area of the work-plane to the total soil mass(separation ratio).A single-factor test was carried out with the amplitude,vibration frequency,and forward speed as factors.The results indicated that:1)There were outstanding strong-weak cycles in the traction resistance and driving torque,due to the gradient throwing characteristics of oscillating slat shovel,soil viscosity,and plasticity.In the strong period,there was a large interaction force between shovel slat and soil,where the maximum separation distance occurred at the middle point of the separation area at the end point of the cutting stroke.2)The amplitude was negatively correlated to the traction resistance,but positively correlated with the driving torque and separation distance.The vibration frequency was negatively correlated to the traction resistance,driving torque,and separation spacing.The forward velocity was positively correlated to traction resistance,driving torque,but negatively correlated to the separation distance.3)There was a small influence of amplitude and vibration frequency on the separation ratio.There was a low separation of oscillating slat shovel,with the increase of forward velocity.4)A combination of parameters was achieved when the amplitude was 7-11 mm in the strong period,where the average traction resistance was about 1580.93-2019.9 N,the maximum driving torque was about 224.04-322.11 N·m,and the maximum separation distance was about 59.58-98.3 mm.5)The average traction resistance was about 1416.43-1866.38 N,the maximum driving torque was about 315.28-364.19 N·m,and the maximum separation distance was about 78.43-94.67 mm when the vibration frequency was 6.67-10.67 Hz.6)The average traction resistance was about 1429.43-2110.48 N,the maximum driving torque was about 241.27-387.78 N·m,and the maximum separation distance was about 62.5-102.5 mm when the forward speed was 0.2-0.4 m/s.An optimal combination of parameters was selected for the field experiment:the amplitude was 9 mm,vibration frequency was 9.4 Hz,working speed was 0.32 m/s.The licorice harvesting test indicated that the traction resistance was about 32.17 kN,the driving torque was about 802.02 N·m,the excavation depth was about 468 mm,and the cleaning rate was about 96.42%.Consequently,the oscillating slat shovel harvesting device can be feasible for the smooth and orderly operation,as well as the higher separation performance of rhizome-soil,where all the operation indexes met the national standards.This finding can provide a new method and design reference for the energy-saving and efficient harvesting of rhizomes,especially deep rhizome crops.