This research was conducted to assess the performance of a combine harvester, 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 double-speed double-action threshing and separating unit. These functional parameters were set at 5 levels. The responses were obtained in terms of broken rate, impurity rate and loss rate. Multi-objective variable optimization was performed using Design-Expert software. Analysis of variance was done to determine the significant effects of the factor variations on the response values. Design-Expert 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 0.15-1.13% respectively. At cylinder speeds of 15.42/18.50m/s and 22.92/27.50m/s rpm, the impurity rate increased from 0.31-1.62% respectively. It was also realised 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 0.40-1.60 m/s, the percentage of impurity rate increased significantly from 0.31-1.62% respectively. However, the lowest impurity rate was obtained at an average linear speed of concave sieve of 0.99 m/s.Furthermore, it was realised that increasing the cylinder-concave clearance from 16-30 mm, equally increased the percentage of loss rate from 1.78%-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 concav of 0.99m/s , gave a better performance of the machine. Field tests show that the prototype has stable performance, with the loss rate, impurity rate and breakage rate of 1.74%, 0.45% and 0.34% respectively. With each performance index superior to the test standard, this device solves the contradiction between impurity removal, entrapment and grain breakage loss during the harvest of Yongyou 15 super hybrid rice effectively.

Tian Liquan, Zhang Zhengzhong, Xiong Yongsen, Lv Meiqiao, Jin Rendiao. Development and experiment on 4LZ-4.0 type double speed and double action rice combine harvester. International Journal of Frontiers in Engineering Technology (2020), Vol. 2, Issue 3: 1-15. https://doi.org/10.25236/IJFET.2020.020301.

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