| Buckwheat has a high nutritional value and health care function.It is recognized as an excellent food and medicine crop by the Food and Agriculture Organization of the United Nations.The increase in yield and quality has been payed worldwide attention.Harvesting operations,as the last important step in the production of buckwheat,have an important impact on the yield and quality of buckwheat.Because buckwheat has the same harvesting characteristics that the plant maturity is inconsistent with while the mature grain is easy to fall off.Due to the inconsistency of the mature period of the buckwheat and the easy falling off of the mature grains,buckwheat is harvested.The study found that two mechanized harvesting are the best mechanized harvesting method.It is found that picking up mechanized harvest is the best way of mechanized harvest.The use of the harvesting test platform for obtaining the relevant design parameters of agricultural harvesting machinery that is an effective approach to solve the impact of seasonal,climatic and geographical conditions on the development process of harvesting machinery,which is of great significance to the research and development of agricultural harvesting machinery.Based on the material characteristics of buckwheat,a new type of scraper-type picking device and threshing device suitable for buckwheat picking and harvesting operation were designed.And a buckwheat picking and harvesting test platform was also built.On this platform,the effects of the picking loss ratio and breakage rate of buckwheat caused by the scraping and picking device as well as threshing device were investigated.The main conclusions of this study are as follows:(1)Based on the research of buckwheat material and mechanical properties,a collecting and harvesting test platform was designed.The picking and harvesting test platform are consisted of five parts: buckwheat conveying device,picking device,intermediate haulage conveyor and threshing device and control system..The conveying speed of the buckwheat conveying device was controlled by the frequency converter.The new picking device was mainly composed of scraper picker,auxiliary picking roller and auger to realize the low loss picking of the buckwheat.The power of the intermediate conveyor and the picking device were provided by the same motor.The threshing device employed a double-roller with a cutting flow and a lateral axial flow.And the threshing drum was a combination of a strut-shaped strut and a rod tooth.The drum speed was also controlled by a frequency converter.The measurement and control system is mainly composed of electronic control switch and speed sensor.(2)Design modeling and simulation analysis of key components of the picking and harvesting test platform were carried out.The key parts of the collecting and harvesting test platform were designed,modeled and simulated.Based on SolidWorks software,the three-dimensional modeling of the scraper picker,auxiliary pick-up roller,double-roller threshing device,buckwheat conveying device and frame of the pick-up test platform was designed.And the pre-assembly and interference check of the test platform were conducted,which laid a good foundation for the production and assembly of the test platform.The simulation of the scraper and the auxiliary pick-up roller was established by the Adams software.Then,the motion of the scraper and the auxiliary pick-up roller was simulated and analysed.The results show that the force exerted by lambda or pick-up roller on buckwheat material increases significantly with the increase of lambda.(3)The buckwheat picking and threshing test platform was built and its performance was tested.The test results showed that the speed adjustment range of the material conveying device was 0.3~2 m/s,the inclination adjustment range of the scraper picker was 0~30°,and the picking speed adjustment range of the picking device was 0.71~1.88 m/s.The drum speed adjustment range of the threshing device was from 500 r/min to 900 r/min.The above parameters met all the test requirements.It accords with the requirements of buckwheat picking and threshing test.(4)The test platform of buckwheat picking and stripping was studied by orthogonal and single factor test method,and the test results showed that in the process of picking up,with the increase of the speed of pick-up,the speed of material transportation and the angle of picking up the pickup plate,the loss rate of picking up was reduced first and then increased.There is no multivariate linear regression relationship between this three factors and the loss rate of picking up,and the grain breakage rate decreases gradually with the increase of buckwheat feeding,but the loss rate of degranulation increases,and the increase of roller speed can reduce the loss rate of degranulation,but the grain breakage rate will increase.There is a linear regression relationship between feed volume and drum speed and stripping loss rate and breakage rate. |
