穴盘苗吹叶补苗机构设计与试验

针对叶片遮挡穴盘苗空穴机械补苗作业时存在损伤待补空穴周围穴盘苗叶片的问题，该研究提出一种使用射流气管吹开遮挡叶片进行机械补苗的吹叶补苗方法。作业时，射流气管内通高压气流，由待补空穴底端渗水孔向上移动，吹开遮挡叶片，到达穴盘苗叶片顶部后，补苗机械手夹持待补苗使基质块底部靠近射流气管顶端，并与射流气管同步下移完成补苗作业。吹叶机构射流气管内径5 mm，顶端封闭，靠近顶端的水平截面均布开设8个直径1.2 mm的射流孔。搭建由吹叶机构与挂接于Denso机械手臂的补苗机械手组成的试验装置，对72穴穴盘培育的红掌、白掌、芥蓝、菜心、白菜和生菜6种不同叶片遮挡程度的穴盘苗进行单穴吹叶补苗性能试验。结果表明，吹叶机构与补苗机械手协同作业的补苗成功率与穴盘苗初始叶片遮挡率（穴盘待补空穴被相邻穴盘苗叶片遮挡的面积与穴孔面积的比值）、遮挡叶片倾角和射流气管压力有关。在射流气管射流孔数为8，射流孔直径1.2 mm条件下，射流气管压力为0.28 MPa时，初始叶片遮挡率59.4%的红掌穴盘苗的补苗成功率可达92%；射流气管压力为0.22 MPa时，初始叶片遮挡率56.2%的白掌穴盘苗的补苗成功率可达94%；射流气管压力为0.22～0.31 MPa时，初始叶片遮挡率35.4%的芥蓝穴盘苗的补苗成功率均可达90%；射流气管压力为0.16～0.31 MPa时，初始叶片遮挡率29.7%～35.8%的菜心、白菜和生菜穴盘苗的补苗成功率均可达90%。研究结果可为叶片遮挡穴盘苗空穴的机械补苗设备开发提供技术参考。

Design and experiments of the mechanism of blowing leaves and replanting of plug seedlings

In the seedling filling operation, there were some damaged leaves of plug seedlings around the vacancy tray cell to be filled, particularly on those plug seedlings under leaf covered. In this study, a feasible device with jetting air tubes was proposed to integrate with blowing leaves and filling plug seedlings. The main part of the blowing leaves mechanism was a jetting air tube with an inner diameter of 5 mm. There were 8 jetting holes with a diameter of 1.2 mm in the horizontal section near the top, where the jetting air tube was closed. During the operation, the high-pressure airflow in the jetting air tube moved upward from the seepage hole at the bottom of the hole to be filled, thereby blowing away the sheltered leaves, concurrently cooperated with the seedling filling manipulator to complete the seedling filling. A Fluent 15.0 software was selected to simulate the airflow field produced by the jetting air tube, in order to investigate the distribution of flow velocity at the outlet of jetting air tube. The number of jetting holes was set as 6, 7 and 8 in the simulation. The ratio C was defined as the section area ratio of air tube to that of all jetting holes, which was set as 1, 2 and 3. The results of fluid simulation showed that an ideal surface of jetting flow radiation was obtained when the number of jetting holes was 8, and the jetting flow cannot contact the substrate block of plug seedlings. A performance test was selected to determine the optimal C value. An experimental device was performed on six types of plug seedlings with different leaf coverage, including Anthurium, Spathiphyllum, Chinese kale, Guangfu No.1 flowering cabbage, Chinese pakchoi, and Italy elite lettuce. The blowing leaves mechanism was integrated with the seedling filling manipulator that attached to the Denso manipulator. The results showed that the filling success rate of seedlings was related to the initial leaf coverage rate of plug seedling leaves (the area ratio of holes to be filled covered by the leaves of adjacent plug seedlings to that of all holes), the inclination angle of plug seedling leaves, and the pressure of jetting air tube. There were obvious peaks in the filling success rates of two flowers plug seedlings, while there was only a slight increase in those of four leafy vegetables, as the flow pressure of jetting air tube increased. The filling success rates of all types showed first increased and then decreased with the increasing of ratio C. Therefore, a better performance was achieved, where the C value was selected as 2, the diameter of jetting holes was 1.2 mm, the pressure range of jetting air tube was 0.10-0.31 MPa, and the number of jetting holes was 8. In the Anthurium plug seedlings with an initial leaf coverage rate of 59.4%, the filling success rate of seedlings reached 92%, when the pressure of jetting air tube was 0.28 MPa. In the Spathiphyllum plug seedlings with a 56.2% initial leaf coverage rate, the filling success rate was 94%, when the pressure of jetting air tube was 0.22 MPa. In the plug seedlings of Chinese kale with a 35.4% initial leaf coverage rate, the filling success rate was 90%, when the pressure of jetting air tube was 0.22-0.31 MPa. When the pressure of jetting air tube was 0.16-0.31 MPa, the filling success rate all reached 90% in the plug seedlings of Guangfu No.1 flowering cabbage, Chinese pakchoi, and Italy elite lettuce with an initial leaf coverage rate of 29.7%-35.8%.