锥盘式撒肥装置的性能分析与试验

Performance analysis and experiment on granular fertilizer spreader with cone disc

针对目前大多数撒肥机在作业过程中存在抛撒不均问题,该文设计了一种锥盘式撒肥装置。通过对该装置结构和工作原理的阐述及肥料颗粒在撒肥盘、叶片上和空气中的动力学和运动学分析,建立了肥料颗粒的运动模型。以叶片长度、叶片水平投影倾角、撒肥盘转速、肥箱落肥口位置和面积为试验因素,以肥料抛撒的横向变异系数为试验指标进行了台架试验。试验表明,当落肥口位置(落肥口中心点在以叶片旋转中心在地面的投影为坐标原点的空间直角坐标系中的坐标值)为(70 mm,0,800 mm),叶片长度为150 mm,落肥口面积为2456 mm2,叶片水平投影倾角为1°,撒肥盘转速为1090 r/min时,横向撒肥变异系数为5.215%,此时肥料抛撒的均匀性最好,满足施肥作业要求。该装置基本上解决了肥料抛撒不均方面的不足,为锥盘式撒肥机的设计与优化提供了参考。

In order to improve the problems such as uneven spreading for most fertilizer machines and the incorrect and unreasonable application of chemical fertilizer on potato, therefore, a cone disc spreader device for fertilizer spreading was designed for granular fertilizer. Inverted cone angle structure was adopted in the cone disc and two groups of vanes mounted on it. The whole organization and working principle of the device were described, and also the performance of the device was analyzed. The kinematics and dynamics analysis of granular fertilizer on spreader disc, vane and in the air were carried out. Through the above theoretical analysis, the motion models of granular fertilizer were established on the two processes mentioned above. The static bench tests were carried out in College of engineering, Northeast Agricultural University at the beginning of October 2015. The static test referred to ISO（international organization for standardization） 5690 and ASAE（American society of agricultural engineers） S341.2 in America. The test was carried out in the room, in order to reduce the effects on fertilizer spreading because of the speed of wind, the air humidity and so on. Urea was selected as experiment sample. The size guide number of urea was 2.41 mm and the density of urea was 1 265 kg/m3. Total amount of fertilizer for each test was 5 kg. The fertilizer was collected in a series of collecting boxes place on the ground in a certain way. The number of collecting boxes was 253. The collecting box had external dimensions of 200 mm×200 mm×100 mm and its thickness was 4 mm. Quadratic orthogonal rotary combination tests were carried out for the cone disc spreader device. The experimental factors of bench test included position of fertilizer export, length of vane, area of fertilizer export, pitch angle of vane in horizontal plane, rotational speed of disc. Coefficient of variation was test index. The experimental data was processed and optimized by Design-expert 8.0.6. The regression model between the test index and the factors was obtained. Meanwhile, the response surfaces were established between the coefficient of variation and the test factors in order to obtain the relationship intuitively. Test results showed that when the position of fertilizer export was（70 mm, 0, 800 mm）, length of vane was 150 mm, area of fertilizer export was 2 456 mm2, pitch angle of vane in horizontal plane was 1° and rotational speed of disc was 1 090 r/min, the coefficient of variation was 5.215%. At this time, the coefficient of variation was smallest, so that the uniformity of the fertilizer was the best to meet the requirements of the application. Verification mobile test were carried out in the early November 2015. The air humidity was about 65%, the temperature was-10°--1° and the speed of wind was very small. This test was carried out in outdoor. The place that conducted the mobile test has a hard and uniform surface in College of engineering, Northeast Agricultural University. The fertilizer was also collected in a series of collecting boxes place on the ground. The number of collecting boxes was 260. Fertilizer and external dimensions of collecting boxes used in mobile test were the same with those in static test. Test results showed that the coefficient of variation for cone-type fertilizer device after optimization was 5.35% and it was consistent with optimized results. The research provides a better solution for uneven distribution of fertilizer of currently machinery in China and provides a theoretical reference for design and optimization of the cone disc distributor.