Experimental Research Of Longitudinal Axial Threshing And Separating Performance Of Rape Combine Harvester

Threshing and separating device is one of the key components of rape combine harvester and it is in relation to threshed rate, entrainment loss rate and energy consumption directly. This paper takes the threshing and separating device as the investigation object. Structural design and laboratory experiment of threshing and separating were conducted. On the basis of the optimum combination of structural and operating parameters, tangential-longitudinal rape combine harvester was developed to conduct the threshing and separating experiment. The major points were generalized as follows:1) Structural design of threshing and separating device. The structure of threshing and separating device was determined and the technology of longitudinal axial threshing and separating was put forward based on systematic analysis of the status and the development of threshing and separating devices of different types at home and abroad and the target of reducing power consumption and improving threshing and separating performance. At the same time, the key parameters such as roller length, roller diameter, threshing gap and arrangement of threshing unit were designed in order to develop a threshing and separating device whose threshed rate was high and entrainment loss rate was low.2) Threshing and separating performance experiment of threshing and separating device. Threshing and separating performance was conducted and the evaluation indexes were threshed rate, entrainment loss rate, un-threshed rate, loss rate before threshing, the proportion of each part material and the chopped degree of stalks discharged. The longitudinal axial threshing and separating device and tangential longitudinal threshing and separating device were developed to conduct comparative test of threshing and separating performance on spike tooth, short rasp bar, combination of spike tooth and short rasp bar and long rasp bar. The longitudinal axial threshing and separating device was used to conduct single factor test and the influence factors were longitudinal axial roller speed, threshing gap, inclination angle of longitudinal axial roller, space between two short rasp bars and the wrap angle of concave. It concluded the change rules of threshed rate, entrainment loss rate, the chopped degree of stalks discharged influenced by different factors. Four factors and three levels orthogonal experiment was conducted and longitudinal axial roller speed, inclination angle of longitudinal axial roller, space between two short rasp bars and wrap angle of concave were selected as influence factors. Meanwhile, three factors and three levels orthogonal experiment was conducted and tangential roller speed, longitudinal axial roller speed and feeding amount were selected as influence factors. Experiment results indicated that the optimum combination of tangential roller speed was20°, space between two short rasp bars was100mm, longitudinal axial roller speed was800r/min and wrap angle of concave was160°. t provided gist for design of tangential-longitudinal rape combine harvester.3) Overall design and experimental research of tangential-longitudinal rape combine harvester. On the basis of the optimum combination of structural parameters and operating parameters, rape combine harvester was developed and design of key parameters, main structure and the operating principle were recommended. The combine harvester was used to carry out the experimental researches by the following:①Single factor experiment of tangential-longitudinal rape combine harvester was conducted and it concluded the change rules of threshing and separating performance index and material proportion of each part influenced by different factors. The four factors were tangential roller speed, forced feeding roller speed, longitudinal axial roller speed and threshing gap respective.②According to the analysis results of single factor experiment, a central composite rotatable orthogonal experimental design of response surface methodology was employed for finding the optimum combination of structural parameters and operating parameters effecting on the threshing and separating performance. Tangential roller speed, forced feeding roller speed, threshing gap, longitudinal axial roller speed and feeding amount were selected as input variables. Threshed rate, entrainment loss rate, un-threshed rate and the chopped degree of stalks discharged were selected as response functions. Interaction relationships of different factors were concluded and the optimum combination of the tangential roller speed was330.17to349.98r/min, the forced feeding roller speed was872.68to900.00r/min, the threshing gap was21.99to29.95mm and the longitudinal axial roller speed was800.00r/min, the threshed rate and the entrainment loss rate had met the design requirement.③Meanwhile, the central composite rotatable orthogonal experimental design of response surface methodology was employed again for finding the optimum combination of structural parameters and operating parameters for the best material flow distribution allocation. Tangential roller speed, forced feeding roller speed, threshing gap, longitudinal axial roller speed and feeding amount were selected as input variables. Material proportion of each part was selected as response functions. Interaction relationships of different factors were concluded and the optimum combination of the tangential roller speed was341.63r/min, the forced feeding roller speed was765.42r/min, the threshing gap was23.50mm and the longitudinal axial roller speed was800.00r/min, the best material flow distribution allocation was that the proportion of material under the sieve was52.56%, the proportion of rapeseed inside the material under the sieve was44.25%, the proportion of material discharged was27.90%, the proportion of lost material before the header was7.33%and the proportion of residue in the device was12.31%.4) Field validation test of tangential-longitudinal rape combine harvester. Field validation test was conducted and test results indicated that the operating performance of cutting, threshing and separating, transporting and cleaning were fine when rape combine harvester was harvesting in the field. It met the desired functional requirements and provided gist for the improved design of tangential-longitudinal rape combine harvester.