Combine Harvester Rotor Finger Support Stress Distribution
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Solution Overview
Problem
The existing axial flow separators in combine harvesters face stress-related failures at the welds between crop engaging elements and the rotor core, leading to costly and inconvenient complete replacement of the separating rotor due to damage from catastrophic events like pieces of steel passing through the rotors.
Innovation Solution
A separating rotor design featuring a rotor core with crop engaging elements having a finger support and planar finger elements, where each foot is secured to the rotor core and extends beyond the finger element's plane, distributing force and minimizing stress on the rotor core, and includes cut-outs to prevent rotational movement, allowing the finger elements to absorb impact without damaging the rotor core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crop engaging elements are welded to the rotor core, then the separating rotor can effectively separate grain from straw, but the welds are prone to failure under stress from catastrophic events
Solution Approach 1:
The crop engaging element is divided into distinct components: a finger support with feet for mounting to the rotor core, and a separate finger element for crop engagement. This segmentation allows the feet to distribute loads to the rotor core while the finger element can independently absorb impact stresses, preventing weld failure.
Solution Approach 2:
The finger support acts as an intermediary component between the rotor core and the finger element. The feet of the finger support provide a distributed mounting interface to the rotor core, while the finger element extends beyond the feet to engage crop material, creating a load distribution pathway that protects the rotor core from direct impact.
2Reliability
If complete replacement of the separating rotor is required after damage, then the separating function is restored, but the cost and inconvenience increase significantly
Solution Approach 1:
By segmenting the crop engaging element into a finger support and finger element, the design enables selective replacement of only the damaged finger element rather than the entire rotor assembly. The finger support remains attached to the rotor core and can be reused, significantly reducing repair costs and downtime.
Solution Approach 2:
The finger element is designed as a sacrificial component that can be easily removed and replaced when damaged, while the finger support and rotor core are recovered and reused. This approach minimizes waste and reduces the frequency of complete rotor replacements.
3Stability of the object's composition
If the finger element is fully supported across its width, then structural stability is improved, but the design complexity increases
Solution Approach 1:
The finger support is segmented into multiple feet distributed across the width of the finger element. This segmentation provides multiple attachment points to the rotor core, stabilizing the finger element against rotational movement while maintaining a relatively simple overall structure that can be manufactured from sheet material.
Data Source
AI summary
A separating rotor (32) for a combine harvester (10) is provided having a rotor core (43) and a plurality of crop engaging elements (42). Each element (42) has a finger support (50) and a finger element (58) attached to the finger support. The finger support comprises a pair of feet (52, 54) connected together by a finger attachment plate (56) wherein the finger element is attached to the finger attachment plate. Each foot is secured to the rotor core along a respective base edge (52a, 54a) which resides on both sides of an extended plane defined by the associated finger element.