| At present,the demand of domestic and foreign market for vegetables continues to rise.Therefore,domestic vegetable production needs to accelerate the promotion of mechanization and the most critical step is to achieve the mechanization of sowing.Seed rope weaving is a relatively mature sowing mechanization technology.By using this technology,the seeds can be discharged on the containment belt according to the seed spacing requirements and twisted into seed ropes through the weaving equipment.In this way,the burying of the seed ropes by the direct seeding equipment can be realized.Nowadays,however,the existing weaving machine uses rice as the object of operation rather than vegetables.As a result,due to the smaller size of vegetable seeds,the variable shape and higher precision of the seed spacing,it is necessary to design a new type of equipment to meet the requirements of vegetable seed rope weaving.By selecting the air-suction seed metering device,the whole machine overall structure is constructed.Combining hardware selection,key components such as the seed metering device assembly,paper tape output assembly,seed rope weaving and winding assembly is for further research.The problem that some vegetable seeds are difficult to absorb can be solved by using pelleting and the performance of the seed metering device can be further improved by designing a stirring propeller and a detachable negative pressure disc.The needle blocking and air blowing device are adopted to improve the precision of seeding as well.Considering the important influence of the negative pressure hole diameter and pressure on the seed suction performance,FLUENT software is used to simulate the seed metering device and obtains the negative pressure aperture 1.5mm,and the negative pressure value 2KPa,under which situation,the seed suction performance of seed metering device works best.Through the theoretical analysis of the seeding process of the seed metering device,it is found that the theoretical seed distance is related to the speed ratio of the stepper motor.Under the condition of zero-speed seeding,if the speed ratio range is controlled,the phenomenon of seed rolling can be reduced accordingly.The concave guide mechanism and the adhesive brushing mechanism are adopted to improve the precision of seeding.The relationship between the theoretical seed pitch,the feed speed of the paper tape and the pulse frequency of the stepping motor is derived,and the frequency of the stepping driver transmitted to the stepping motor is changed to realize the adjustment of the seed pitch and the speed of the paper tape.By combining the realization of functions,the control system software design of the lower computer,and the upper computer as well as communication software are completed.By testing the tensile strength of the paper tape and the cotton thread,the average tensile strength of the paper tape and the cotton thread as well as the best unit twist number can be obtained.At the same time,by designing forward and reverse knitting transmission mechanism,the relationship between winding shaft speed and pulse frequency can be derived.In addition,the spiral winding mechanism is adopted as well to realize the swing type winding of the seed rope.Therefore,solutions to seed rope breakage by means of the motor-controlled and mechanical spring-type speed regulating mechanism are proposed.Finally,by combining the evaluation indicators of seed spacing qualification rate,replay rate and missed seed rate,a single factor test and orthogonal regression test on the prototype are carried out on the key factors like seed metering speed,seed meter negative pressure and paper tape feed speed.At last,cucumber and rape seeds are selected for overall performance test under the best parameters,and the qualified rate of seed spacing is 90% and 95% respectively,which can meet the requirements of seeding,showing the design of the whole machine is reasonable. |
