Design and performance test on segmented-differential threshing and separating unit for head-feed combine harvester

Area of Science:

• Agricultural Engineering
• Mechanical Engineering
• Agronomy

Background:

• Conventional threshing units for combine harvesters face challenges with incomplete threshing, grain loss, and breakage rates, particularly for super hybrid rice.
• Existing head-feed combine harvesters struggle to balance threshing efficiency with minimizing damage to delicate grains.
• Addressing these limitations is crucial for improving the overall efficiency and economic viability of rice harvesting operations.

Purpose of the Study:

• To develop and evaluate a novel segmented-differential threshing and separating unit for head-feed combine harvesters.
• To optimize the working parameters of this new unit to minimize grain loss, breakage, and impurity rates.
• To compare the performance of the new unit against conventional single-speed threshing systems.

Main Methods:

• Development of a segmented-differential threshing and separating unit featuring a coaxial segmented-differential drum and rotary concave screen.
• Implementation of a three-factor quadratic regression orthogonal rotation combination design test, varying drum speed, screen velocity, and chain speed.
• Analysis of test results using Design-Expert software to establish a mathematical model and determine optimal parameters; comparative testing with a conventional unit.

Main Results:

• The developed segmented-differential unit demonstrated superior performance in reducing harvest losses and grain damage.
• Optimal working parameters were identified: low-speed/high-speed drum rotation at 505/680 r/min, rotary concave screen linear velocity at 1 m/s, and clamping chain speed at 1.26 m/s.
• Under optimal conditions, the unit achieved a grain loss rate of 1.94%, a breakage rate of 0.21%, and an impurity rate of 0.56%.

Conclusions:

• The segmented-differential threshing and separating unit effectively addresses the limitations of conventional systems in super hybrid rice harvesting.
• The optimized parameters provide a robust guideline for maximizing harvesting efficiency while preserving grain quality.
• This technological advancement offers significant potential for improving rice combine harvester performance and reducing post-harvest losses.