蔬菜穴盘育苗底部气吹式钵体松脱装置设计

针对蔬菜穴盘苗直接拔苗费力又损伤大的问题,设计了一种有助于穴盘苗移栽的气吹式钵体松脱装置。利用直线模组移位单元和双联气缸升降单元组合成输送系统,驱动气嘴排从穴盘底部的穴孔排水口逐排顶吹穴盘苗钵体,实现穴盘苗钵体与穴孔壁之间非机械接触式放松,利于移栽时人工轻松拔苗或机械快速夹取。对关键部件进行设计,使用排气孔直径为5mm的气嘴,能确保气体射流从128穴孔排水口有效顶吹穴盘苗钵体而不顶盘,根据亚声速自由气体射流动力学原理计算表明:当气嘴口空气射流压力大于0.098 MPa,不超过0.235 MPa时,所设计的气嘴能将穴盘苗吹松而不破坏苗钵根土结构。开展气力顶钵松脱多因素试验研究,结果表明气流喷射压力高度显著影响苗钵完整率,钵体含水率对完整率影响显著,其他苗龄、气流回路流量、气嘴头有无海绵密封等试验因素没有统计学显著性影响。当气嘴回路中气流喷射压力控制为0.2 MPa,钵体含水率为55%～60%,黄瓜苗龄为25 d,气流回路全开,气嘴没有海绵头铺垫时,对穴盘苗顶吹作用达到既能将穴盘苗钵体顶松脱离穴孔壁粘附,又最大程度保证钵体完整度的效果。开展验证性试验,苗钵气力松脱完整率达到96%以上,完成整盘苗放松约48s,满足实际需要。该研究可为开发省力的穴盘苗钵放松装置和边松脱边取苗的高效无损自动取苗机构提供参考。     

温室穴盘苗自动移栽机设计与试验

针对种苗从高密度穴盘移植到低密度穴盘,或者从穴盘直接移植到花盆的温室穴盘苗移栽生产需要,设计了一种轻简型自动移栽机。利用成熟的直线模组和无杆气缸组合设计出自动移栽机械臂,驱动取苗末端执行器往复于来源盘和目标盘进行取苗、移苗、栽苗操作,采用双排链传动实现穴盘和花盆输送,对穴盘苗的夹取操作采用气动两指四针钳夹式夹钵取苗方法。根据所设计的移栽机工作要求,构建电气控制系统。试制样机,开展试验研究。采用直线位移传感器系统检测分析机器取苗移栽移位性能,结果显示对于128/72孔穴盘苗,移栽效率分别达到1 221株/h和1 025株/h,运用单样本t检验法分析得到实测取苗移位间隔与理论设定穴孔间隔无显著差别,标准差低于0.5,整机工作精度准确。以当地自行培育的种苗为移栽对象,进行温室穴盘苗移栽生产试验,对比分析自动取苗移栽效能,结果显示多种穴盘苗移栽成功率平均达到90.70%,苗钵夹取破碎率低于5%,自动取苗移栽效果较好。     

蔬菜穴盘苗自动精确移栽组合式取苗机构设计与测试

Precision planting is one key point of precision agriculture.A doorframe type swing seedling pick-up device for the automatic precise field transplanter was designed and tested in a laboratory.The seedling device could automatically extract seedlings from growing trays, transfer them, and release them into the planting unit where they were to be precisely transplanted into the ground.It consisted of a path manipulator and two grippers.The path manipulator for seedling extraction was constructed with creative design of Ⅱ-type mechanism combination in series.It consisted of an oscillating guide linkage mechanism and a grooved globoidal cam mechanism.According to the planned seedling pick-up trajectory, the design of the path manipulator for seedling extraction was finished with a set of the closed loop vector equation.The gripper was a pincette-type mechanism using the pick-up pins to penetrate into the root mass for seedling extraction.It consisted of multiple pick-up pins, U-type pull rod, shaft, stop block, compression spring and frame.The mechanical dimensions of the gripper were determined by the tray size and plant characteristic with a set of rectangular equations and the boundary constraint conditions.The final gripper was developed on the basis of cultural practice for vegetable seedling in China.A prototype of the seedling pick-up device was constructed to examine whether its working efficacy was satisfactory or not.According to the analysis on the work process, the seedling pick-up device could precisely complete a work cycle of approaching, penetrating, extracting, transferring, erecting and discharging a seedling.Taking pepper seedlings, tomato seedlings and cucumber seedlings as the transplanting objects, the performance tests were conducted to evaluate the practicality and adaptability of the pick-up device.The laboratory evaluation showed that the pick-up device equipped with two grippers could extract 70 seedlings per minute with an average success ratio of 90.49%.The quality of extracting seedlings was satisfactory.     

新型蔗苗移栽机的设计与研究

国内外研制的移栽机并不适用于蔗苗移栽,因此,设计了一种适用于蔗苗移栽的移栽机械.通过有限元软件对蔗苗移栽机机架进行静力学分析,结果表明:所设计蔗苗移栽机机架工作负载下的最大综合位移为1.873 mm,最大应力为65.386 MPa,最大应力小于移栽机机架材料的屈服强度235 MPa,符合强度和刚度设计要求.     

基于Micro-CT的黄瓜苗坨夹取破损检测及取苗参数优化

为了减小自动移栽时取苗爪夹取苗坨的破损,利用X射线Micro-CT对处于夹取状态的黄瓜苗坨进行检测,用阈值分割方法将根系和孔隙从断层图片中分割提取并三维重构。在垂直和水平方向将苗坨划分成6等份,对根系和孔隙的体积和分布密度进行统计,得出夹取过程中根系未发生显著位移,根系的作用是将基质缠绕包裹住,防止苗坨散坨;孔隙的体积和分布密度变化非常显著,新生孔隙的聚集和裂缝的形成是导致苗坨破损的主要原因。苗坨中夹针收缩移动的区域、夹针的顶端部位和苗坨的顶部是破损的主要部位,用这3个区域孔隙体积的增加量作为评价苗坨破损量的指标,对圆形和扁形2种夹针,在夹针直径为2、2.5和3 mm,夹取初始角为7°、9°和11°时进行扫描试验,得出在夹针收缩量为5 mm时,减小夹针直径和增大夹持初始角可以减小苗坨破损量,相同夹取条件下圆针夹取苗坨的破损量小于扁针;在夹取力等于苗坨屈服点的抗压力7.31 N时,圆针和扁针的收缩量分别为4.75和4.26 mm,此时孔隙体积的增加量分别为843.7和786.1 mm~3,扁针夹取苗坨的破损量小于圆针。以苗坨质量损失25%作为考核指标,在自动取苗机构上进行试验,结果表明,在夹针直径为2 mm,夹取力和夹取初始角分别为7.31 N和11°时,苗坨的破损率为6.3%,小于其他参数的试验结果,与Micro-CT扫描分析的结论一致。