蒜种盒机械投放过程运动学分析与参数优化试验

针对种盒式大蒜播种方案,为检验倾斜输送带式蒜种盒投放方式的可行性,设计了预植蒜种的可降解蒜种盒和输送带式种盒投放试验台。对蒜种盒投放过程进行了运动学分析,建立了蒜种盒运动速度、输送带倾角与投放后相邻蒜种盒间隙等相关参数间的数学模型,明确了蒜种盒投放间隙的影响因素及变化规律。通过蒜种盒投放过程的受力分析,确定了蒜种盒触地后不与地面产生滑动的条件和方法。为了验证理论分析结果和大蒜播种方案的可行性,进行了输送带倾角、行驶速度等单因素试验和正交试验,结果显示,输送带倾角为30°、试验台运动速度为0.75 km/h,投放效果较好。输送带倾角对前后蒜种盒投放后的间隙影响显著,通过优化蒜种盒长度两端尺寸,可有效消除投放后蒜种盒衔接间隙,保持播种株距稳定。

Kinematic analysis and parameter optimized experiment of garlic box putting process

Abstract: Garlic is one of the major cash crops in China. Because of the special requirements of garlic planting, for which there isn't mature machine at home and aboard, and garlic planting is still done by worker. According to the fact that the planting state of garlic, this paper designed the garlic box and garlic planting test bed with tilt conveying belt. The garlic box was made of degradable protection material such as waste paper pulp and plant straw. The test bed consisted of frame, tilt conveying belt, guiding device, adjustable speed motor, transmission system, pulley, axle of pulley, ground wheel, angle adjusting device of tilt conveying belt, and so on. The garlic planting test bed was powered by adjustable speed motor. According to the garlic box dropping requirements end to end, the transmission ratio between conveyor belt and planting test bed was determined and its value was 1. When the test bed worked, the garlics were put into the garlic box by worker or machine at first, and the boxes were then put on the tilt conveying belt and conveyed to the ground. This paper analyzed the conveying process of the garlic box, and established the mathematical and graphic model about moving velocity of garlic box and clearance of adjacent garlic boxes. The result showed that the clearance of adjacent garlic boxes decreased first and then increased with the tilt angle of belt rising, and the relationship between the clearance of adjacent garlic boxes and the guide plate was positive correlation as the tilt angle of conveying belt was the fixed value. This paper also researched the force condition of garlic box when dropping, made clear the relative motion state between garlic and ground, and analyzed the conditions that could avoid relative sliding between garlic box and ground taking the 30° tilt angle of belt as the example. The analysis result showed the garlic box slided along the belt and the sliding could be avoided by adjusting the connecting position between guide plate and conveying belt to the one with the tilt angle of 16° between garlic box and ground. The result of single-factor experiment showed the test bed could work accurately and reliably, and it could satisfy the requirements of garlic box dropping; the tilt angle of belt and the velocity of test bed had effects on the clearance of adjacent garlic boxes, and the fluctuation range of the clearance of garlic boxes was very small (< 6 mm); the best conditions were the 30° angle of tilt conveying belt and the speed of test bed of 0.75 km/h respectively, under which garlic box did not slide during the experiment. The result of two-factor test indicated the tilt angle of conveying belt had significant effect on the clearance of adjacent garlic boxes, the order of the factors impacting the clearance of garlic boxes was tilt angle of conveying belt > running speed of test bed, and the best test combination for garlic box dropping was the angle of tilt conveying belt of 30° and the velocity of test bed of 0.75 km/h, under which the clearance of adjacent garlic boxes was 20.4 mm; the garlic boxes could be well connected as they were subtracted by 10 mm at the 2 ends of the box.