Designing And Experimental Study On Threshing Device Of Stripping Combine

The threshing step is a key step in the process of crop harvesting.The indexes such as threshing rate and entrainment loss rate have a direct impact on the working effect of the whole machine.The threshing device is one of the key components to ensure the quality of the harvesting machinery.Comb-type harvesting refers to the harvesting process of cutting the heads and branches of the crops directly by the comb-cutting table before the cutting of the crop stems.After the harvesting of the header,only the grain,the broken ear and a small amount of short stalk enter the threshing mechanism,so the power consumption required for the completion of the threshing process is reduced,the work efficiency is improved,and the screening and cleaning operation load is reduced.At present,the research focus of domestic comb-type combine harvesters is mainly on the comb-cutting table.There are few studies on the detachment device,and most of the detachment devices are obtained according to various threshing devices already in existence.Since the composition of the comb-off mixture and the full-feed harvesting mixture are greatly different,this means that the structure and the motion parameters of the threshing device of the comb-type combine harvester and the full-feed combine harvester are completely different,so the comb-off type is harvested.The structural design and experimental research of the threshing device in the machine is very important.The paper designed a re-detaching device suitable for threshing of rapeseed combs.The threshing device is mainly composed of auger,planetary gear mechanism and threshing components.The focus of this paper is to analyze the threshing principle of the threshing device,design and check key components,and conduct experimental research.The main completed contents include:(1)Analysis of the principle of threshing.The composition of the rapeseed comb-off mixture brushed by the comb-cutting table was analyzed to obtain the content of un-stripped fruit pods,short stems,and rapeseed grains.Based on the principle of rolling-type threshing,the design of the material of the conveying blade and the threshing of the side of the planetary gear mechanism is proposed.(2)Structure design of the threshing device.According to the design concept of threshing while conveying,the structure of the combing and threshing device is designed,and the three-dimensional design of the key components such as threshing element,spiral conveying blade and planetary gear mechanism is carried out by Pro/E software,and the whole virtual prototype assembly is carried out.(3)Design of conveying and threshing parts.Through the formula of the relationship between the feeding amount of the screw conveyor and the various parameters of the screw conveyor,the length of the screw conveyor is designed to be 1300 mm,the outer diameter of the spiral blade is 320 mm,and the pitch is 260 mm.Depending on the selected threshing principle,the appropriate threshing elements are matched and the position of the threshing elements is reasonably arranged.The length of the threshing element was designed to be 220 mm,and the number of threshing elements per planetary shaft was 5,and the range of the threshing gap was determined to be 3-18 mm.(4)Design of planetary gear transmission mechanism.According to the requirements of threshing operation and the characteristics of the planetary gear shaft,gear parameter design and gear shaft strength design are carried out.The number of teeth of the design sun gear and the planetary gear are 57 and 53,respectively,and the gear module is 2 mm.The shaft diameter of the designed planetary gear shaft is 26 mm.According to the movement principle of the planetary gear mechanism and the center distance of the gear,a reasonable planetary frame structure is designed.(5)Degranulation performance test.On the test bench of self-made threshing device,the factors of threshing gap,screw conveyor speed and fruit pod feeding were taken as the influencing factors,and the single-factor test was carried out with the target rate of fruit pod threshing as the main control target.The rate of threshing of the pods has a certain effect.Based on the single factor experiment,the design of the three-factor three-level quadratic regression orthogonal test was carried out through the Box-Benhnken Center combined experimental design theory.The response surface analysis was carried out on the test results,and the corresponding regression model was established to determine the regression items.The impact is significant.Through the analysis of the effect of the orthogonal test results,it can be seen that the order of influence of the three test factors on the test results is from the largest to the smallest,the threshing gap,the speed of the screw conveyor,and the feed amount.The parameters were optimized according to the target rate of fruit pod threshing.The optimal parameter combination of the threshing device was determined as the threshing gap was 5 mm,the screw conveyor speed was 162.6 r/min,and the fruit pod feeding amount was 200 g/s.Under this optimized condition.The threshing rate of the pod was 95.1%.