| Chinese rice planting area and total output rank first in the world,but the degree of mechanization in planting is still low.Although the factory-based seedling cultivation has already begun,it still relies mainly on manual placement in the field of tray paving.With the increasing labor costs in recent years in China,domestic relevant enterprises and colleges have paid more attention to automatic paving in the field,and have successively developed equipments such as seedling cultivation machines,tray placement machines and loaders.The main shortcomings are the need for excessive participation of farmers,low degree of automation,and limited efficiency.In contrast,the foreign tray placement machine has a high degree of automation,and the corresponding cost is relatively expensive.However,the placed tray is only applicable to their own products and is difficult to localize.Based on the above situations,this paper aims to replace the manual placement in the field by developing a fully automatic rice tray placement machine.According to the specific design indicators and requirements,various design schemes are proposed,and then the total design scheme is determined by comparison.Then the hardware and software design of the mechanical design and control system is carried out around the overall scheme,and the prototype is developed.In this way,we break through the key technologies of mechanical release,the specific contents are as follows:1)According to the site and the agronomic requirements of the paving,three general schemes are proposed.Through the comparison of the schemes,it is finally determined that the fully automatic gantry orbital rice tray placement machine is the main plan of this paper.2)Design the mechanical structure of the tray placement mashine.The running track,the group-disassembled gantry truss and the paving trolley were constructed by multi-segment splicing,and the static analysis of the gantry truss was carried out by ANSYS workbench.3)For the efficient and reliable paving,a combined cam type tray placing mechanism is designed.A mathematical model for solving the cam profile curve is established.The program is written and calculated by MATLAB,and the structure of the entire tray-discharging mechanism is designed.Finally,by using Adams virtual simulation technology,the motion simulation test and calculation and analysis of key components are performed on the tray-discharging mechanism.At the same time,the existing trays are optimized and improved to make them suitable for the operation of the tray.4)Design and build a control system for the placement machine.A closed-loop control system with a programmable controller as the control core,a human-computer interaction interface as the operation control terminal,a servo motor and a sensor as execution controls are established.It realizes two control modes:automatic paving and manual placing.5)In the load-bearing test of the gantry truss,when the paving trolley was tested in the middle of the gantry truss and the load of 70kg was applied,the intermediate deformation of the truss was about 13mm,which met the requirements.In a total of 120 release tests,the success rate of the release can be 100%when placed in a cassette of 8-10 trays per turn,and the placing mechanism is operated at 500-600 rpm.Finally,in the automatic laying test,the paving trolley was moved at a speed of 5 cm/s on the gantry truss,and the placing mechanism was placed at a height of about 100 mm from the ground at a speed of 550 rpm.At this time,the yield rate of the release plate can reach 94.89%,and the paving efficiency can reach 360 trays/h. |
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