原位混肥挖坑回填复式果树栽植机设计与试验

为避免土壤连作障碍,果树幼苗栽植时需将树穴土壤与菌肥充分混匀,以提高果树成活率。针对果树栽植过程中混肥质量差、作业流程分离且劳动强度大的问题,设计了一种原位混肥挖坑回填复式果树栽植机。根据栽植农艺要求对关键部件进行设计,挖坑混肥回填装置实现挖坑混肥同步进行,垂直挖坑进给、肥料计量排放及原位回填浇灌,根据原位作业距离确定举升装置各连杆长度,动力传动系统实现机器的行进及液压栽植动力分配。开发了相配套的栽植作业控制系统,并依据监测油压表征的作业负载,实现基于PWM控制的挖坑进给量实时调节。针对菌肥少土壤多的混匀难题,使用离散元(DEM)技术模拟不同转速、不同掺混时间下菌肥和土壤在掺混腔的掺混过程,通过相对标准偏差法分析树穴中不同深度土肥混合物的掺混均匀度变异系数,得到最佳理论掺混作业参数:转速250 r/min、掺混时间14 s。田间验证试验表明,样机单次栽植作业总时间在3 min内,树穴上、中、下3层掺混均匀度变异系数均不超过16%,作业深度为0~400 mm可调,作业直径为500 mm,样机各项指标符合果树栽植农艺要求。

Design and Experiment of In-situ Fertilizer Mixing Integrated Digging and Backfilling Planter for Fruit Tree

In order to avoid the obstacles of soil continuous cropping,it is necessary to mix the soil in the tree holes with the bacterial fertilizer to improve the survival rate of fruit trees.Aiming at the problems of poor quality of mixed fertilizer,separation of operation flow and high labor intensity in the process of fruit tree planting,an integrated fruit tree planting machine was developed.The key components were designed according to the requirements of planting agratics.The backfilling device of pit mixing fertilizer realized simultaneous excavation and fertilizer mixing,vertical pit feeding,fertilizer metering and discharge,and in-situ backfilling and watering.The length of each connecting rod of the lifting device was determined according to the in-situ operating distance.The plant operation control system developed realized automatic plant operation,and real-time adjustment of pit feeding amount based on PWM control according to the operation load characterized by oil pressure monitoring.Against the blending problem of less bacterial manure and more soil,the discrete element simulation was used to simulate mixing process of soil in the mixing chamber at different rotational speeds and mixing time,net-poles through the analysis of the relative standard deviation method in different depths,and soil mixture mixing evenness variation coefficient,and the best theory mixing operation parameters were got as follows:the speed was 250 r/min,and the mixing time was 14 s.The results of field validation test showed that the total time of single planting of the prototype was less than 3 min,the variation coefficient of mixing uniformity of the upper,middle and lower layers of the tree hole was not more than 16%,operating depth was adjustable from 0 mm to 400 mm,and diameter was 500 mm,all indexes of the prototype met the agronomic requirements of fruit tree planting.