揉碎玉米秸秆螺旋输送性能试验分析

Test and analysis of performance of screw conveyor for rubbing and breaking corn straw

针对螺旋输送装置输送农业纤维物料功耗大、生产率低、效率低等问题,该文分析了螺旋输送装置的输送性能指标和螺旋叶片受力,找出了影响叶片受力的主要因素。利用自行研制的压力测试系统和功耗测试系统对螺旋叶片受到的压力和输送装置的功耗进行了测试。针对螺旋叶片所受压力、输送功耗、生产率和输送效率等输送性能指标,研究了螺距、螺旋轴转速和喂入量对输送性能的影响。结果表明,在喂入量70 kg/min、螺旋轴转速58 r/min、螺距160~300 mm的范围内,当螺距250 mm时平均输送功耗最低,为294.63 W;螺距为300 mm时输送效率和生产率最高,分别为90%和58 kg/min。在螺距250 mm、喂入量70 kg/min、转速58~148 r/min的范围内,当转速117 r/min时生产率最高,为65 kg/min。在螺距250 mm、螺旋轴转速117 r/min、喂入量10~70 kg/min的范围内,当喂入量70 kg/min时生产率最高,为42 kg/min。该研究为研制适合输送农业纤维物料的螺旋输送装置提供了参考。

Screw conveyor is one of most important agricultural machineries for crop harvest and fiber materials processing. The advantages of screw conveyor include simple structure, small volume, compact total size, easy operation and management, and good seal. There are 3 major problems in use that are high loss of power, low productivity and transmission inefficiency. This study was to explore the method to reduce power consumption and improve efficiency and productivity in transportation. First, with stress analysis of the screw blade, the research found the factors that influenced the force of the blade. This research also designed blade stress test system and power test system by using thin-film pressure sensors, data acquisition unit, signal receiver, torque speed sensor and computer. The experiment was implemented by taking the screw conveyor as experimental platform, which was developed by the project group. The parameters of the experimental platform were as follows： the conveying gap length was 2 500 mm, the diameter of the screw blade was 250 mm, the diameter of the center axis was 60 mm, the pitch was 200, 250 and 300 mm respectively, and the space between the screw blade and the casing was 5-8 mm. The experiment samples were from the corn stalks rubbed and broken by the 9R-40 type rubbing machine, which had less than 180 mm length, 2-8 mm width, and 43.98% moisture content. Based on the performance index such as pressure on the blade, transmission power, productivity and transmission efficiency, the experiment studied the impact of pitch, speed, and feeding quantity on transportation performance. The results showed that： 1） Under the same pitch, the closer to the outer edge, the greater the pressure on the helical blade, and the pressure at inner diameter was the minimum. On the same shaft, the pressure was different at different points of screw blade, the closer to the spout, the greater the pressure on all parts of the blade. 2） When the speed was 58 r/min and the feeding quantity was 70 kg/min, with the pitch increasing, the pressure on each part of the blade increased, the productivity increased and the transmission efficiency was enhanced. When the pitch was 250 mm, the average power consumption was 294.63 W which was the minimum. When the pitch was 300 mm, the transmission efficiency was 90% that was the highest. 3） When the pitch was 250 mm and the feeding quantity was 70 kg/min, as the speed increased, the pressure on different parts of the blade increased, the power consumption increased, the productivity first increased and then decreased, and the transmission efficiency decreased. Consequently, for transporting agricultural fiber material, the optimum speed was 117 r/min. Under such condition, the average power was low, 354.63 W, and the transmission efficiency was high, 75%. 4） When the pitch was 250 mm and the speed was 117 r/min, with the increase of feeding quantity, the pressure on all parts of the blade increased, the transmission power and the productivity increased, and the transmission efficiency reduced. Therefore, the feeding quantity should be determined according to the requirement in practical work.