茄果类嫁接机砧木上苗装置设计

Design of stock feeding device of grafting robot for solanaceae

针对国内外嫁接机性价比偏低的问题,该文以华南农业大学的高速嫁接机2JT-1600型流水线式茄果类嫁接机为基础,分别在砧木上苗工位和接穗上苗工位增设嫁接用苗输送链和转接手,实现砧木和接穗均单人上苗,成倍提高了嫁接机作业人员的上苗生产率。通过分析传递过程中带土坨砧木的受力情况,确定转接手结构尺寸,并且研制了具有较好拾苗性能的交叉闭合式送苗夹,其拾苗容偏能力可达5 mm。为防止在输送过程中砧木由输送链的苗座内脱出,选用高弹性橡胶贴合在苗座槽口上夹持砧木,以砧木弯曲度、苗座槽口深度及苗座槽口橡胶厚度作为影响因素,考察苗座槽口对嫁接用苗的夹持性能,试验结果表明当苗座槽口深度为8 mm、苗座槽口所用橡胶厚度为3 mm时,苗座可保证95%以上的砧木不脱出苗座,增设上苗装置后,可保证2JT-1600型流水线式茄果类嫁接机在2 000株/h的生产率条件下,实现1 000株/h的人均嫁接生产率,综合上苗成功率达到92%以上。

At present, both domestic and foreign grafting robots have the problem of low cost performance ratio. In order to increase in per capita productivity to improve cost performance ratio, this paper selected 2JT-1600 assembly line solanaceous fruit grafting robot（2Jt-1600B） researched and developed by South China Agricultural University, and split a working position that completed both seedling feeding and seedling cutting into 2 working positions that separately completed seedling feeding and seedling cutting based on the improved feeding seedling device by adding seedling seat and transmitting manipulator. The process that feeding device feeds stock to grafting robot can be divided into 2 phases： transportation phase and transmitting phase. In transportation phase, one operator places stock on seedling seat repeatedly, and seedling seat is circulated step by step together with conveying chain to transport stock to the position; slot is designed on seedling seat to provide convenience for positioning and placement of stock. As nursery substrate is attached on stock, the center of stock is deviated to the side of nursery substrate, thus leading to the trend of overturning from seedling seat. In order to prevent stock falling out from seedling seat when transporting, highly elastic rubber is selected to be fixed on slot to give friction force for stock to overcome falling by squeeze of rubber with stem of stock. In transmitting phase, transmitting manipulator picks up stock, and transfers it into holding device of grafting robot after rotating by 90°. In order to prevent transmitting manipulator harming the stock, by analyzing the stress of stock in the rotation of transmitting manipulator, the structural sizes of transmitting manipulator were affirmed. The seedling holder was also developed to pick seedlings up in crossed closing form. After the test, seedling holder was found to have a tolerance of 5 mm. In order to dock transmit manipulator with seedling seat and holding device, two-piece design was adopted for seedling holder and seedling seat. In this paper, the design and experiments are both mainly focused on the structure parameter of seedling seat. In transportation phase, when stock is excessively bending to place inside the slot, it is easy to cause alignment difficulty or crush stock owing to two-piece structure of slot. So, it is required to straighten seedling. The operation will influence feeding efficiency. When the depth of slot is bigger to hold stock, and the suspension rubber above seedling seat is longer, thus the ability of rubber deformation is favorable, it is easy to place stock into the slot, but the stroke of stock at the slot bottom is increased. When the depth of slot is shallow and the rigidness of slot is bigger, it is easy to crush seedling. When the thickness of rubber used for slot is changed, it will influence the deformation ability of slot and lead to the changes of friction between stock and slot wall, which will cause the changes of holding performance. The test of holding parameters of seedling seat, which were the curvature of stock, depth of slot and thickness of rubber, was conducted under grafting productivity of 2000 seedlings per hour. When stock is not damaged or falling out while being placed into the slot of seedling seat and transferred to picking position of transmitting manipulator via seedling seat, the position is considered to be suitable to pick by transmitting manipulator and the experiment is regarded to be successful. Test results showed that when the stock bending was chosen within the 95% percentile（6.55 mm）, the depth of upper slot of seedling seat reaches 8 mm and its rubber was 3 mm thick, the holding function of seedling seat could achieve 100%, and the feeding success rate of transmitting manipulator could reach 92%. Due to the working position station split, the operation cycle is shortened, the grafting productivity reaches 2000 seedlings per hour, the feeding device implements feeding stock and scion on single, and per capita productivity increases to 1000 seedlings per hour.