Design And Study On Vegetable Automatic Seedling Pick-up Device

Transplanting is one of the most significant steps in vegetable-production process. And automatic transplanter with the advantage of high efficiency and low labor cost is the development tendency of vegetable transplanting technology instead of existing technology-manual transplanting and semi-automatic transplanter-with a limit efficiency. However, working performance of seedling pick-up mechanism which is the key component of automatic transplanter is still a bottle-neck. Therefore, in this study, a vegetable automatic seedling pick-up device was developed on the basis of theoretical analysis, virtual modeling and experimental research, after analyzed the advanced technology at home and abroad. Conclusion was as follows:1.The seedling push-out force testing was made base on the fcators of water content, diameter of mandril, and push-out speed. And got the relations between pressure and compressible displacement of seedling pot. The results showed the moisture content and mandril diameter had obvious effect on the push-out rate. The push-out rate decreased with the incerease of moisture content and the decrease of mandril diameter. The push-out rate achieve 100% was substrate at 35.09% moisture content, meanwhile the mandril diameter was 8mm. The push-out rate was only 81.25% when substrate at 35.09% moisture content, meanwhile the mandril diameter was 5mm. The capacity of resistance for compression sharp increased with the increase of deformation, and the pressure force was 48.89N,43.87N,35.85N when the deformation reach 12mm at the three moisture content.2. Mathematical model of each mechanism of vegetable automatic seedling pick-up device was built and made the kinematics analysis of push-out mechanism. A visualization vegetable automatic seedling pick-up device timing analysis program was developed in Microsoft Visual Studio development environment, for matching the action of each mechanism, and analysising the influence law of trajectory affected by the model parameters. The optimal parameter combination was φdd=108°, a=78mm, b=112mm, e=20mm,φf=15°,φk=135°.3. Finite-element analysis of seedling clamp was made based on software ANSYS Workbench.The von-mises stress nephogram and total deformation under the force displacement 2mm～4mm in the top of seedling clamp and the compressive resistance of seedling pot were obtained, which verified the feasibility of seedling clamp.3D model of all parts of vegetable automatic seedling pick-up device were built, the virtual assmeble was also carried out which provided the design reference for the prototype. The dynamic simulation results verified the correctness of the theory model.4. A vegetable automatic seedling pick-up device was developed which made good results in performance testing. The test with empty tray showed that it run smoothly when the seedling pick-up frequency was 140 strains per minute, and heavy vibration was found in the seedling pick-up manipulator when the frequency was 200 strains per minute. The results of seedling pick-up test showed that the device could high efficient pick-up the tray seedlings. When the seedling pick-up frequency was 140 strains per minute, the success rate of the seedling pick-up was still more than 95%, which completely meet the agronomic requirements. The moisture content should below 30%, because of the loss rate of substance will inceease when the moisture content increase. When the moisture content was 43.09%, the average loss rate of substance was 40%.