勺夹式藠头排种器设计与试验

    Design and experiment of the spoon clip type seed metering device for Allium chinense

    • 摘要: 针对藠头(Allium chinense)种植劳动强度大、人工成本高等问题,该研究设计了一种由排种盘、取种勺、取投种凸轮、种箱、安装板等组成的勺夹式藠头排种器。对该排种器工作原理和取种、携种、投种过程进行理论分析,建立离散元仿真模型,对取种过程进行仿真分析,确定了最优种勺结构。以大叶藠为对象,以取种合格率和漏取率为试验指标,进行种勺直径、种勺深度、取种起始角、种面高度与种箱高度之比和取种速度5因素显著性筛选试验,并以种勺直径、取种起始角、种面高度与种箱高度之比为试验因素进行回归正交试验;采用Plackett-Burman试验法和Box-Behnken中心试验法建立取种合格率和漏取率的回归模型,并进行参数优化,获得最优参数组合为种勺直径27 mm、取种起始角30°和种面高度与种箱高度之比92.5%。在最优参数组合下进行台架试验,得到取种合格率91.17%,漏取率6.17%。田间试验结果表明在前进速度0.1~0.2 m/s的条件下,该排种器平均播种合格率、平均重播率和漏播率分别为63.10%、12.76%和24.14%。研究结果可为藠头播种机械的研究与设计提供参考。

       

      Abstract: Allium chinense, as a characteristic vegetable, is exported to Southeast Asian countries such as Japan and South Korea with remarkable economic benefits. Aimed at the problems of Allium chinense planting, main including high labor intensity and artificial planting process cost, a spoon clip seed metering device for Allium chinense was designed. It consists of a seed metering disc, spoon, seed taking and discharging cam, seed box, mounting plate, and other components. The working principle of the spoon clip seed metering device for Allium chinense, and the mechanism of seed taking, seed carrying, and seed discharging were expounded by analyzing the stress state and movement state of Allium chinense seeds in the working process of seed metering device. The seed taking process of the seed metering device was simulated using discrete element simulation software to optimize the spoon for different structures. The Plackett-Burman test method was used to select the significant factors of spoon diameter, spoon depth, start angle of seed taking, ratio of seed surface height to seed box height, and speed of seed taking. Qualified rate of seed taking and missing rate of seed taking were used as test indexes. Orthogonal regression tests were carried out with spoon diameter, start angle of seed taking, and ratio of seed surface height to seed box height as experimental factors. Regression models of qualified rate of seed taking and missing rate of seed taking were established, and parameters were optimized. Field test were conducted to examine the field seeding performance of the seed metering device for Allium chinense based on obtaining optimal parameters. Simulation results show that the type of spoon has a high significance on the qualified rate of seed taking (P<0.01). Qualified rate of seed taking of the round spoon is more excellent than the other two spoons at different speeds, with an average value of 91.14%, and the round spoon is selected as the preferred structure through comprehensive analysis. According to the results of the Plackett-Burman test, diameter of spoon has a highly significant effect on the missing rate of seed taking (P<0.01), and ratio of seed surface height to seed box height has a significant effect on both the qualified rate of seed taking and missing rate of seed taking (P<0.05). The analysis of the effects of the test factors and their interactions on the test indicators in the Box-Behnken test shows that the test regression model is highly significant (P<0.01). The interaction of spoon diameter and start angle of seed taking have a significant effect on the qualified rate of seed taking. Under the condition that other factors are determined, the qualified rate of seed taking increases with the increase of pickup diameter and then decreases. The qualified rate of seed taking decreases with the increase of the start angle of seed taking for smaller spoon diameters and increases with the increase of the start angle of seed taking for spoon diameters larger than 25 mm. The optimal parameters are as follows: spoon diameter is 27mm, start angle of seed taking is 30°, and ratio of seed surface height to seed box height is 92.5%. Under the optimal parameter combination, the filling qualified rate and missing rate of seed taking were obtained, they were 91.17% and 6.17% respectively, which were consistent with the predicted results of the model. Observations of the field test process indicate that the seed metering device can complete the whole process of seed taking, seed carrying, and seed discharging in the field environment. The results of the field seeding test show that the average seeding qualified rate is 63.10%, and the average multiples rate and seeding missing rate are 12.76% and 24.14%, respectively, at the forward speed of 0.1-0.2 m/s. According to the operating quality for single seed metering device can satisfy the field operation. However, stability and efficiency can still be further optimized and improved. The research can provide a reference for the research and design of planting machinery for Allium chinense.

       

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