| Corn pot transplanting can increase the accumulated temperature,advance the seeding time and extend the crop growth period,and it is important to improve maize yield and quality.There are good air permeability and water permeability of paper bowl,and the material of paper bowl is biodegradable.When transplanting,there is no separation between seedling and paper bowl,and this can decrease the rate of seedling damage.From the status of development of domestic and foreign transplanting machine,it can be seen that the main difference between automatic transplanting machine and semi-automatic transplanting machine is the difference between the way of seedling and the degree of automation of the device.The performance of the seedling mechanism has a significant effect on the transplanting effect and the survival rate of the seedlings after transplanting.Based on the structural characteristics of the tube-seedling transplanting machine,this paper designed an automatic cutting seedling device to meet the requirements of seedling agronomic and transplanting,to improve the efficiency of seedling,reduce the damage of seedling and reduce the labor intensity.Firstly,in order to determine the best way to destroy paper bowl and the size of the required force.The mechanical properties of paper bowls were studied by three kinds of failure modes,including bending,tangent and slipping,and the variation of three destructive modes with the displacement was analyzed.The results show that: slip-cut is the best way to cut,the required cutting force is the smallest and the degree of paper bowl after cutting is the highest.Secondly,the design goal of automatic cutting seedling device was put forward,the three-dimensional model of the automatic cutting seedling device was established,the interference test and the kinematics simulation of the device were carried out,and the finite element analysis of the key part cutting tool was carried out.The results show that there is no interference;when the force of 50 N or 100 N was applied to the cutting edge,the deformation amounts were 0.00266 mm and 0.00399 mm respectively.Deformation is small,so it proves that the seedling device design is reasonable.PLC,stepper motor,cylinder and sensor were designed and analysis,the PLC control procedure was compiled,cutting knife was driven by the cylinder to do the reciprocating linear motion to cut the bowl seedlings,and conveyor chain was driven by the stepper motor to intermittent transport seedlings,to achieve coordinated control of automatic cutting seedling mechanism.Finally,the automatic cutting seedling device test bed was built according to the three-dimensional design model of cutting seedling,and the parameters of the device were experimentally studied.The scope of factors,influence order of factors on the sub-seedlings success rate and the best combination of parameters were determined through the single factor and orthogonal test design.SPSS and MATLAB were used for data analysis.The experimental results showed that when the cutting edge was 55 °,the frequency of seedling was 90 / min,and the cutting speed was 0.625 m / s,the success rate was 84.2%,integrity of bowl seedlings was high,and seedling effect is good.In summary,through the study of the mechanical properties of paper seedlings,to obtain the required range of cutting force was 30N-40 N.On this basis,the automatic cutting seedling device controlled by PLC was designed,and obtained the best parameter combination by experiment.The automatic cutting seedling device designed in this paper is of great significance to improve the degree of automation,reduce the consumption of labor force and seedling damage rate,and lay the foundation for promoting the development of automatic corn transplanting machine. |
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