| Seedlings transplanting whose comprehensive benefits includes high and stable yield,climate compensation and improving land utilization rate is a vital part of the dryland crop production process.At present, the crop transplanting mainly rely on manual and semi-automatic transplanter in China.Semi-automatic transplanting machines have been popularized and transiting to full automatic in foreign developed countries.It is of great significance to realize full-automatic seedlings picking,delivering and planting integration transplanting through increasing the research on automatic seedlings picking system for dryland transplanting machines. Aiming at the problem of the current low level of transplanting machine automation and the high rate of injury in the seedlings picking-delivering link,research on seedlings picking-delivering system of automatic transplanting machines is carried out in this paper.This article is consist of 3 main contents,(1)Design of mechanism,The design of tray stepping mechanism includes the design of seeding-tray holder link gear mechanism,the optimization of seeding-tray holder’s tilt angle and the design of parameters of encoder transmission rack and gear. The design of rows of seedling pushing up and picking up system includes the design of seedlings pushing up mechanism,the configuration design of seedlings pushing up bar and the bars’ bracket and driving force connecting frame,dynamics model construction and structural parameters optimization of driving bogies and the design of pneumatic seedlings clamp. The design of seedlings catching mechanism,delivering mechanism, stirring up mechanism and seedlings dropping mechanism..(2)The design of gas-electric-hydraulic control system includes the design of hydraulic circuit of transplanting machines,the design of pneumatic control system and the design of control system flow chart.(3)The experiment is made up of three aspects,including testing on performance parameters of pepper seedlings,single factor tests on test bench and field test with experimental machine.Performance parameters of pepper seedlings is consist of mechanical parameters and physical parameter.Mechanical parameters of pepper seedlings testing includes pepper seedling bowls bearing pushing up force and pulling force test.Physical parameter of pepper seedlings testing is arranged to get the height of seedlings,the width of seedlings blade span,the mess of seedlings,the seedlings shape,rate of water content in seedlings’ base material and so on. Single factor tests whose experiment index are seedlings integrated injury rate and seedlings picking success rate target set the pressure of seedling pushing up cylinder and the pressure of seedling clamping cylinder as the experiment factor respectively.Field test with experimental machine whose experiment index are leakage transplanting,repetition transplanting,lodging transplanting,injury seeding and pass ratio of picking and transplanting set Picking frequency,Speed of transporting seeding and transplanter speed as the experiment factors to carry out Orthogonal experiment of three factors and four levels.The main findings of this paper include 5 aspects.(1) A seedlings picking-delivering system of automatic transplanting machines has been designed.It can realize seedling tray fixing and steppingautomatically and accomplish the work of seedlings pushing up,seedlings clamping,seedlings catching,seedlings stirring up,seedlings delivering and seedlings dropping automatically,it can effectively improve the quality of transplanting and solve the problem of the labor intensity of the semi-automatic transplanter, this system provides a reference for the automation of the transplanter.(2)The motion model of driving connecting frame of seedlings pushing up bar is established by theoretical analysis.And it is converted into MATLAB optimization equation to optimize structural parameters.The result obtained show the length of rotating bar BO is 131 mm, the length of CO is 143 mm,the length of CD is 80 mm,the included angle between BO segment and CO segment is 128 °.(3)The physical and mechanical properties of pepper seedlings were studied,based on the data of the test,we did a contrast test of cylinder pressure,the results show that the optimal working pressure of the drive cylinder driving seedlings pushing up mechanism is 0.4 MPa and that of the drive cylinder controlling the opening-closing of clamps’ clamping piece is 0.25 MPa.(4) The functional relationship among 3 parameters which are the frequency of picking up seedlings, the speed of delivering seedlings,and the forward speed of transplanting machine are obtained through theoretical analysis. Besides,levels of these 3 factors are optimized, the 4 groups of best combinations of the factors are achieved,and orthogonal experiment is conducted, in which experimental indices are missing ratio of seedling transplanting, seedling repeated planting ratio, seedling lodging ratio, and seedling damage ratio.Through analysis on the experiment result, it reflects that the system achieves the best quality of seedlings picking up and delivering when the frequency of picking up seedlings is 7 times/min, the speed of delivering seedlings is 42 m/min, and the forward speed of transplanting machine is 20 m/min. |
PDF Full Text Request