Design And Experiment Of A Multi-rows Pneumatic Precision Metering Device For Rapeseed

Rapeseed is the most important oilseed plant for edible oil supply in the middle-lower Yangtze River area in China.Direct precision planting of crop seed is the best solution for assuring homogeneous plants establishment and high seed yield with lower cost.Currently,vacuum type precision seeding is widely used in rapeseed planting machines.Seed pick-up by vacuum plate and release is necessary to occur precisely without seeds miss,multiple or damage.Recently invented metering device for rapeseed precision could be used effectively for precision seeding,with simple transmission and pressure systems for metering four rows simultaneously.A multi-rows pneumatic disk device can be broadly utilized in seeding operation which is capable of metering different seeds with different size and shape.Depending on the seed properties of rape,the prototype metering element was designed with a suitable hole shape and size,a number of holes in the row,combined with an adjustable seed flow clearance to provide and keep seed level available for the four rows.The main objective of this study was to design a single pneumatic disk with four-rows for metering rapeseed and investigate its performance using some techniques coupled with several rotating speeds and vacuum pressure values.This research mainly aimed to reduce the use of separate planting units for metering separate rows in a precision planter which decidedly results in planter complexity.Seed pick-up by the rows at different rotating speeds and vacuum levels was found to be acceptable with some multiple seed pick-up through the rows closer to the plate center of rotation.After the prototype design of the metering device,several methods and techniques have been employed for investigating device performance,in addition to field test.The main research methods and techniques and their results obtained were as follows:(1)Design and experiment of a multi-rows pneumatic precision metering device for rapeseedThe main objective of this study was to design a pneumatic disk with four-rows for planting rapeseed and investigate its performance under several rotating speeds and vacuum pressure values.The effects of rotating speeds,vacuum pressure and rows on seed sucking and retaining were inspected.Six rotating speeds(5 r/min,10 r/min,15 r/min,20 r/min,25r/min and 30 r/min)incorporated with the application of vacuum pressure were employed for detecting the optimum vacuum amount that was sufficient for seed sucking under each speed.These values of vacuum were found to be 1.1 k Pa,1.25 k Pa,1.35 k Pa,1.65 k Pa,1.8 k Pa,and2.0 k Pa,respectively.Moreover,a regression model was developed for predicting of vacuum pressure that corresponds with each rotating speed.Based on seed mass analysis,statistical differences were found at 5% significance under the influence of speeds and negative pressure and also existed between and within rows according to Duncan's Test.The highest seed mass means of 3.17 g and 3.96 g were obtained by row 1 under the effects of speed and vacuum pressure,respectively,while the lowest means of 2.79 g and 3.05 g were attained by row 4.Due to the influence of rows,important differences were occurred between row 1(closer to the center of rotation)and row 4(farther one),particularly under high speeds(25r/min and 30 r/min).Results concluded that a pneumatic disk with multiple-rows could be satisfactorily used for seed sowing with a little variation in seed amount between rows without any seed damage.The rows of hole farther from plate center of rotation were obviously influenced by angular velocity and vacuum amount rather than the closer ones.(2)An evaluation of seed spacing accuracy of a multi-rows pneumatic plate for precision rapeseedThe main objective of this study was to investigate the performance of a single pneumatic plate with four rows for rapeseed precision using an adjustable plastic slice for changing vacuum around the metering nozzle entrance.The slice was located near plate surface at seed pick-up area of rows holes closer to the rotation center of the plate(row 1and2)owing to their multiple seed pick-up.Five clearances between the slice and plate surface have been inspected at 15 and 20 r/min combined with their optimum vacuum amount to detect the best clearance for same rows seed pick-up.Laboratory test demonstrated that 1 mm was the best clearance,which in turns used for verifying seed distribution regularity among the rows.Results disclosed that the optimum negative pressure associated with 15r/min and20 r/min were 1.15 k Pa and 1.25 k Pa,respectively.15r/min resulted in quality index of91.34%,92.83%,91.7% and 90.65%,while 20r/min attained 89.81%,92.23%,89.86% and92.05% for rows 1,2,3 and 4,respectively.The highest seed feed index was obtained by row2 at both speeds,while the lowest value(89.81%)was achieved by row1 at 20 r/min.Both the separate rows stability and rows consistency resulted in less than 2%,with some tendency of 15 r/min to be more consistent than 20 r/min.Results concluded that the multi-rows pneumatic plate coupled with plastic slice technique is able to satisfy the required seed precision without damage which could be employed for further advanced investigations.(3)Performance evaluation of three devices for rapeseed pick-up regularity of multirows pneumatic plateThe main objective of this study was to investigate the effect of three devices on seed pick-up regularity of a single plate with four-rows due to unequal rows seed pick-up.These devices included a plastic slice device for reducing vacuum around rows with multiple pickup;a device with curved-edge for removing multiple seeds by direct contact,and a device employing positive pressure blowing against seeds in the hole.The influence of each device was evaluated under four rotating speeds(5,10,15,and 20 r/min.)coupled with their optimal vacuum levels(0.6,0.9,1 and1.2 k Pa),respectively.Under plastic slice device,1mm and 2mm clearances have been inspected,while six levels of positive pressure(0.2,0.4,0.6,0.8,0.9,and1 k Pa)were investigated with positive pressure device at an interval of 0.2 and 0.1k Pa.Results revealed that the methods attained the different success of rows pick-up and they all were better than the original performance.Positive pressure device attained the best rows pick-up consistency under all speeds with CV ranged from 0.72-2.25%.Curved-edge was lower than the positive device with rows consistency fluctuated between 1.87 and 2.86%,while plastic slice device obtained the lowest results with CV ranged from 2.24-3.78%.Plastic slice and curved-edge produced more rows seed pick-up mass compared with positive pressure device,and also they provided more seed pick-up through row1 than other rows.The values of 0.8,0.9,0.9 and 1k Pa were found to be the best positive pressure values attained the consistent seed pick-up of the rows at 5,10,15 and 20 r/min,respectively.Due to better findings and easy set up of positive pressure and curved-edge devices,results concluded that they could be successfully utilized to improve rows pick-up similarity,while better results can be realized by more adjustment in positive pressure and further modifications in the curved-edge device.(4)A vacuum distribution device for seed pick-up regularity improvement of rapeseed multi-rows pneumatic plateSeed pick-up by a pneumatic plate with multiple-rows requires an exact vacuum value through independent rows to achieve same rows pick-up.The objective of the recent study was to inspect the effect of an adjustable vacuum distribution device on rows pick-up similarity of a multi-rows pneumatic plate due to unequal rows performance.The device was located tightly inside the vacuum cavity as to distribute and direct vacuum to blow only through rows metering nozzles.The influence of vacuum and speed on rows pick-up at 30?opening angle for vacuum passage has been studied.Furthermore,six opening angles were examined at six plate rotating speeds combined with their optimal vacuum values to detect the best angle for attaining same rows sucking.Not only but also 4?,7?,10?and 30?were attempted as different angles through row1,row2,row3,and row4,respectively.Results revealed that under the same speed,and same opening angle,an increase in vacuum provided more consistent rows seed sucking.As vacuum opening angle increase,rows seed mass also increase with an increase in their variation.Row1 and row4 resulted in the highest and lowest seed mass,respectively,under all speeds and opening angles except at 5?angle.Rows consistency CV declined when opening angle or plate speed increased.Rows consistency CV for all angles at mentioned speeds was oscillating between 1.33% and 7.20%,with some tendency of 10?to be more consistent than other angles.Results attained showed that the best CV values of 3.20%,2.38%,1.33%,2.08%,2.70%,and 1.94% at plate speeds of 5,10,15,20,25 and 30 r/min were found to be coupled with the opening angles of 5?,10?,10?,10?,10?and 5? respectively.Results obtained at different opening angles were found to be superior to those attained at same opening angles.They provided closer rows pick-up with CV value of2.01%,1.78%,1.89%,1.34%,1.77% and 2.45% at speed of 5,10,15,20,25 and 30 r/min.,respectively.Results concluded that vacuum distribution device could be satisfactorily used for achieving better rows performance with some adjustments in required vacuum pressure and opening angles.(5)Field experiment and analysisIn this test the performance of the prototype was inspected in the field using Huayouza62 rapeseed as materials during year 2017-2018.Experiments results demonstrated that plant density was fluctuating between 34-40 plants per square meter and their coefficient of variation was found to be lower than 20%.The mean seedlings distribution of the rows was ranging from 9.1-11.7 plants per meter length with rows coefficient of variation of about(10%).The mean of rows plant spacing was oscillating between(94-110 mm)with rows consistency CV of 6.5%.Due to these results and field observations its recommended that for more seed distribution regularity of multi-rows plate,vacuum and positive pressure values should be accurately adjusted in order to avoid seeds missing or damage by the interaction between the two pressures.The innovation points could be drawn from the study are as follows:Innovation point 1: Design of a single pneumatic plate with four-rows metering device for rapeseed precision,which can simultaneously realize four-rows seeding operation and simplify the structure of the planting equipment.Innovation point 2: According to the structural characteristics of the four-rows rapeseed pneumatic seed metering device,a method for evaluating a uniform seed distribution was proposed,and a regression model for the relationship between the rotating speed of the device and the negative pressure was established...