基于水力-机械组合的自走式挖藕机设计与试验

Design and Test of Self-propelled Lotus Root Digger Based on Hydraulic-Mechanical Combination

摘要:

针对人工水力挖藕劳动强度大、雇佣成本高，以及现有采藕机存在无自走功能、采挖效率低等问题，本文设计了一种基于水力-机械组合的自走式挖藕机，设计了履带底盘、水力冲刷系统、水力-机械组合式采挖装置、液压与动力系统等关键部件。建立了螺旋输送器与泥土间相互作用的力学模型，明晰了影响螺旋输送器清泥效果的因素主要为叶片升角、叶片高度、螺旋输送器有效长度、螺旋输送器轴径、螺旋输送器转速、螺旋输送器前进速度和入泥深度，利用EDEM仿真开展了单因素试验和正交试验，结果表明，当叶片升角为25°、螺旋输送器转速为125 r/min、螺旋输送器前进速度为0.05 m/s时，螺旋输送器清泥效果最佳。基于台架开展了以莲藕挖净率A为试验指标，以喷嘴相对螺旋输送器高度h1、喷嘴射流角θ1、水泵吸水深度h2、台架前进速度v2、螺旋输送器入泥深度d和转速n为试验因素的单因素试验和以喷嘴射流角θ1、台架前进速度v2、喷嘴相对螺旋输送器的高度h1为试验因素的Box-Behnken中心组合试验，台架试验结果表明：当喷嘴射流角为24°、台架前进速度为0.048 m/s、喷嘴相对螺旋输送器高度为55 mm时，莲藕挖净率最佳，优化与验证结果分别为97%和95%。田间试验结果表明，基于水力-机械组合的自走式挖藕机挖净率为93.9%，损伤率为2.7%，作业效率为340 m2/h。相比于人工水力挖藕，挖净率提升8.3个百分点，作业效率提升近6倍。

Abstract:

In response to the high labor intensity and high labor costs associated with manual hydraulic lotus root harvesting, as well as the lack of self-propulsion and low harvesting efficiency of existing lotus root harvesters, a design for a self-propelled lotus root harvester was presented based on a hydraulic-mechanical combination. Key components included a tracked undercarriage, a hydraulic flushing system, a hydraulic-mechanical combined harvesting device, and hydraulic and power systems. A mechanical model of the interaction between the screw conveyor and the soil was established, clarifying that the factors primarily affecting the screw conveyor's mud-clearing performance were the blade angle of attack, blade height, effective length of the screw conveyor, screw conveyor shaft diameter, screw conveyor rotational speed, screw conveyor forward speed, and penetration depth. Single-factor and orthogonal experiments were conducted using EDEM simulation. The results indicated that the best mud-cleaning performance was achieved when the blade pitch angle was 25°, the screw conveyor rotational speed was 125 r/min, and the screw conveyor travel speed was 0.05 m/s. Based on a test rig, single-factor experiments were conducted by using lotus root cleaning efficiency A as the test indicator, with the relative height of the nozzle to the screw conveyor h1, nozzle jet angle θ1, water pump suction depth h2, test rig feed rate v2, screw conveyor mud penetration depth d, and rotational speed n as experimental factors. Additionally, Box-Behnken central composite experiments were conducted with nozzle jet angle θ1, the test bench feed rate v2, and the height h1 of the nozzle relative to the screw conveyor as experimental factors. The results indicated that the lotus root cleaning rate of the test bench was optimal when the nozzle jet angle was 24°, the test bench feed rate was 0.048 m/s, and the height of the nozzle relative to the screw conveyor was 55 mm, with optimization and validation results of 97% and 95%, respectively. Field trial results indicated that the self-propelled lotus root harvester, based on a hydraulic-mechanical combination, achieved a harvesting rate of 93.9%, a damage rate of 2.7%, and an operational efficiency of 340 m2/h. Compared with manual hydraulic harvesting, the harvesting rate was increased by 8.3 percentage points, and operational efficiency was improved nearly sixfold.