Reciprocating Sieve Frame Extrusion Design for Fatigue Resistance
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Solution Overview
Problem
The existing reciprocating sieve assemblies in agricultural harvesters face challenges with cyclical loading, leading to fastener loosening and weld failure due to metal fatigue, necessitating a configuration that balances strength, durability, and weight.
Innovation Solution
A reciprocating sieve frame design featuring elongate extruded members with tubular sections and strategically placed apertures for hanger mounts, using blind fasteners to secure the hanger mounts to both the outer and inner walls, distributing loads evenly and preventing buckling, while allowing for lighter construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reciprocating sieve assembly is welded together to prevent fastener loosening under cyclical loading, then the strength and durability are improved, but the risk of weld failure by metal fatigue increases and the weight increases
Solution Approach 1:
The frame is divided into multiple extruded members (first member, second member, first cross member, second cross member) that are joined through fasteners rather than welding. This segmentation allows each component to be independently manufactured and assembled, reducing the propagation of stress concentrations that lead to metal fatigue in welded joints.
Solution Approach 2:
The invention changes the connection method from welding to mechanical fastening with hanger mounts and blind fasteners. This parameter change in the joining technique eliminates the metal fatigue issue associated with welds while maintaining structural integrity under cyclical loading conditions.
2Strength
If the reciprocating sieve assembly uses traditional framing to ensure strength, then the durability is improved, but the weight increases
Solution Approach 1:
The frame utilizes extruded members with tubular sections that combine lightweight materials with optimized structural geometry. The extruded aluminum or alloy members provide high strength-to-weight ratio, allowing the sieve assembly to maintain structural integrity while reducing overall weight compared to traditional solid section framing.
Solution Approach 2:
The invention incorporates tubular sections with hollow interiors, transitioning from solid to hollow cross-sections. This dimensional change reduces material usage and weight while maintaining bending and torsional strength through the tubular geometry, which efficiently resists cyclical loads.
3Weight of moving object
If the sieve assembly uses lightweight construction to reduce weight, then the weight is reduced, but the resistance to cyclical stresses and susceptibility to fastener loosening increases
Solution Approach 1:
The hanger mounts are pre-installed on the extruded members during manufacturing, with apertures precisely positioned and sized. This preliminary action ensures proper fastener alignment and distribution of loads before the sieve assembly enters service, preventing uneven stress concentrations that could cause fastener loosening under cyclical operation.
Solution Approach 2:
The invention uses standardized hanger mount designs that can be replicated across multiple fastening points on the frame. This standardization ensures consistent fastener engagement and load distribution throughout the lightweight structure, maintaining reliability across all connection points.
Data Source
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AI summary
A sieve frame (118, 122) for a combine comprises: a first member (300, 302, 308, 310) that is elongate and has a first end and a second end, wherein the first member extends generally horizontally and in the direction of travel; a second member (300, 302, 308, 310) that is elongate and has a first end and a second end, wherein the second member extends generally horizontally and in the direction of travel, wherein the second member is spaced away from the first member, and wherein the second member is disposed generally parallel to the first member; a first cross member (304, 306, 312, 314) that is elongate and has a first end and a second end, wherein the first cross member extends longitudinally in a direction that is perpendicular to the direction of travel, wherein said first end of said first cross member is fixed with respect to the first member, wherein said second end of said first cross member is fixed with respect to the second member; and a second cross member (304, 306, 312, 314) that is elongate and has a first end and a second end, wherein the second cross member extends longitudinally in a direction perpendicular to the direction of travel, wherein said first end of said second cross member is fixed with respect to the first member, wherein said second end of said second cross member is fixed with respect to the second member; characterized in that the first and the second member are extrusions.