Study On Numerical Simulation And Frame Optimization Of First-stage Thresher

With the development of the tobacco industry,higher requirements for the quality of tobacco products have been put forward.In cigarette production,threshing and redrying is a key step in converting agricultural raw materials into industrial raw materials in the tobacco industry.The quality of the flake structure of the tobacco strips produced during the threshing process directly affects subsequent processes such as tobacco thread and packaging.Therefore,exploring the mechanism of the thresher is of great significance for improving the quality of threshing and redrying products.In this paper,the first-stage thresher was taken as the research object in a threshing and redrying workshop in Yunnan Province,and the effect of temperature,water content,feed flow,beating roll speed and frame on threshing was investigated using a uniform design with the large and medium leaf rate,medium leaf rate,fragment rate,and free tobacco strips rate as the indicators of the threshing effect.The experimental results were analyzed by partial correlation analysis and path analysis,and a stepwise regression model was established between the flake structure and the threshing related factors after firststage threshing.It was determined that the frame had the most significant impact on the threshing effect.Next,a multi-body dynamics model of the thresher was established in Recur Dyn and the frame was classified as a flexible body,and a discrete element model of the tobacco leaf was established in EDEM,and some simulation parameters were calibrated through experiments.A co-simulation model of the leaf beating process was established using Recur Dyn and EDEM,and the simulation of threshing was carried out using a diamond-shaped frame and a hexagonal frame.The visual analysis of the breaking process of tobacco leaves in the simulation results was conducted,and the stress distribution of tobacco leaves subjected to diamond shaped and hexagonal shaped frames during the threshing process was obtained.Finally,according to the stress distribution of the diamond frame and the characteristics of the hexagonal frame,the design was improved on the basis of the original structure of the diamond frame,and three types of frames were processed.Experiments were conducted using the three types of frames and the common diamond-shaped frame,and the experimental results showed that the quality of the flake structure after threshing was the highest correlation with the total length of the edge of the frame.An evaluation system for the first-stage threshing flake structure was established by subjectively and objectively weighting the four key flake structure indicators using analytic hierarchy process and entropy method.The evaluation system was used to score the threshing effect of the four frames,and the score results showed that the optimized three frames were better than the common diamond-shaped frame,and the diamond-shaped through-hole frame with sharp corners had the best threshing effect.This project reveals the mechanism of tobacco leaf breaking in the first-stage thresher and realizes visualization of the threshing process.The action mechanism of the frame in the thresher was studied,and the shape and structure of the frame were optimized to improve the quality of the flake structure of the tobacco leaves after threshing.It provides a new idea and reference for the further optimization design of the frame in the later the threshing equipment.