Mechanism Study And Optimization Design Of Inclined-insert Grafting Device Of Cucurbita Vegetable

Vegetable grafting is the most effective way to avoid the diseases of replanting in the same land. But the efficiency of vegetable grafting by manual is very low. Therefore, it is not able to meet the requirement of agricultural production in our country. Mechanical grafting technique is an advanced technology combined with machanism, automatic control and horticultural technology which has appeared in recent years. It can greatly improve the efficiency of grafting. Therefore, it is essential to development of grafting mechanization in China.The seedings of cucurbita vegetable used for grafting is soft and irregular which make it difficult for mechanical grafting. The clamping and positioning of stocks and scions and removal of growing point is the three most difficult aspects of researchment and designing of grafting device. The main research contents of this thesis are as follows:1. Grafting methods which were suit for cucurbita vegetable were analysised. It was determined to use inclined-insert as the method of cucurbita vegetable grafting which can avoid the root of scion regrowing by using straight-inserting method and lossing of nutrition caused by a leaf being cutoff. The geometrical and mechanical properties character parameter of stock and scion were measured. The cotyledon and growing point characteristic parameter of stock, hypocotyl characteristic parameters and cotyledon pressure resistance characteristic parameters of scion were obtained, which provide a certain foundation for the design and development of grafting machine.2. The stock clamping mechanism of automatic centering and cross laminating was presented, which can avoid stock being damaged caused by the bending of stock in grafting process. The main parameters including the angle of V-type sheet and the hole diameter of clamping mechanism of stock were designed. The clamping force can be adjusted by the spring on both sides. The results show that cross laminated of stock clamping mechanism has no damage to the stock.3. The gas suction mechanism which can prevent the scion be injuried was designed. Under the given boundary constraint condition, the flow field in the head of gas suction was simulated by building3d finite element model in CFD software. It can be concluded that the head of gas suction has good adsorption ablity when the vacuum degree is3kPa, sink-hole depth is1mm, and the suction nozzle of suction head is H-type. Tests showed that the adsorption rate was about97.8%and had no damagment. It provided design basis for solving scion fixed. 4. The growing-point removal finger based on the characteristics of the stock profile was designed. This growing-point removal finger removed the growing-point of stock which was driven by slider crank mechanism. Optimization design was given which based on multi-dimensional variables of minimum size and transmission angle of growth point removal through establishing the kinematics model. Tests showed that the success rate of growing-point removal of new growing-point removal mechanism reached95%which solves the problem of incompletely removed of growing point.5. The hole-making mechanism and cutting mechanism of scion rootstock was reseached. The structure hole-making mechanism and the size of needle were designed with the analysis of stock internal structure. Tests showed that the best stock hole-making angle is about40°, the success rate of cutting mechanism is about98.9%and scion cutting rate of cutting mechanism is about96.7%.6. Through the analysis of inclined-insert grafting design requirements, the overall design and device assemble of inclined-insert vegetable automation grafting mechane was finished. Designed the general process of inclined-insert grafting machine, completed the overall structure design of grafting machine, guarantee graft fast, safe and reliable. It can basically meet the grafting operation and agronomic requirements of watermelon seedling.