Design and Performance Assessment of Dual-Speed Axial Threshing and Separation for Paddy Rice Combines

Abstract

HighlightsDual-speed axial threshing and separation was designed to improve performance.Loosely connected grains were removed firstly for reducing opportunity for breakage.Machine is complex but a lower effective cylinder speed can reach a good performance.Reasonable feed rate and concave clearance could maintain quality and throughput.ABSTRACT. This research was conducted to assess the performance of a combine, model number 4LZ-4.0 under different threshing functional parameters such as speed of high/low speed cylinder, cylinder-concave clearance and linear speed of concave sieve. An indoor experiment was conducted using the dual-speed axial threshing and separation. These functional parameters were set at five levels. The responses were obtained in terms of broken rate, impurity rate and loss rate. Multi-objective variable optimization was performed using Design-Expert 6.0.10 software. Analysis of variance was done to determine the significant effects of the factor variations on the response values. Design-Expert 6.0.10 software was used to present response surface graphs that were used to describe the variations of the responses as the factors changed from one level to the other. Results showed that with an increase in speed of high/low speed cylinder from 15.42/18.50-22.92/27.50m/s, the percentage of broken rate increased significantly from 0.15% to 1.13%, respectively. At cylinder speeds of 15.42/18.50m/s and 22.92/27.50 m/s rpm, the impurity rate increased from 0.31% to 1.62%, respectively. It was also realized that varying the speed of high/low speed cylinder had a significant effect on the broken rate and impurity rate. The impurity rate increased with an increase in Linear speed of concave sieve from 0.40 to 1.60 m/s, the percentage of impurity rate increased significantly from 0.31% to 1.62% respectively. However, the lowest impurity rate was obtained at an average linear speed of concave sieve of 0.99 m/s. Furthermore, it was realized that increasing the cylinder-concave clearance from 16 to 30 mm, equally increased the percentage of loss rate from 1.78% to 2.93%. From the results obtained, it was suggested that operating the threshing cylinder at a speed of high/low speed cylinder of 18.31/21.97 m/s, cylinder-concave clearance of 22.60 mm and linear velocity of rotary concave of 0.99 m/s, gave a better performance of the machine. Keywords: Axial threshing and separation, Cylinder-concave clearance, Dual-speed, Functional parameters, Linear speed of concave sieve, Speed of high/low speed cylinder.