Double-Folding Knife Blade Structure for Longer Portable Blades
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Solution Overview
Problem
Existing folding knives are limited by a blade-to-handle length ratio of approximately 0.8:1, restricting the maximum blade size to the width of a human hand, whereas unfolded knives offer larger but less portable options.
Innovation Solution
A knife design with double folding blades, featuring a first blade member foldable about a first pivot and a second blade member foldable about a second pivot, allowing an extended unfolded blade length ratio up to 2:1 compared to the handle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a single folding blade is used, then the knife maintains portability with a compact handle, but the blade length is limited to a ratio of approximately 0.8:1 between blade and handle
Solution Approach 1:
The blade is divided into two separate blade members (first blade member and second blade member) that can be independently folded and locked. This segmentation allows the total blade length to exceed the handle length by distributing the blade length across multiple foldable segments, resolving the contradiction between achieving longer blade length and maintaining manageable device complexity.
Solution Approach 2:
The second blade member is nested within or attached to the first blade member, creating a hierarchical folding structure. When folded, the second blade member can be stored within the first blade member or alongside it, allowing the combined blade length to extend beyond the handle while maintaining a compact form factor when closed.
2Length of moving object
If the blade length is increased beyond handle width, then cutting capability is enhanced, but the knife becomes less portable and harder to conceal
Solution Approach 1:
The blade structure transitions from a fixed length to a dynamic, multi-position folding mechanism. The blade can be extended to full length for cutting tasks and then folded back into a compact configuration for portability. The locking mechanisms enable the blade to maintain stable extended or retracted positions, resolving the contradiction between enhanced cutting capability and ease of carrying.
Solution Approach 2:
Instead of increasing blade length in a single linear dimension, the design uses multiple folding stages that extend the blade in a multi-dimensional folding pattern. This allows the blade to achieve a length ratio up to 2:1 relative to the handle when fully extended, while folding back to a compact size that maintains portability.
3Length of moving object
If a double folding blade mechanism is implemented, then the blade-to-handle length ratio can reach up to 2:1, but the locking mechanism complexity increases
Solution Approach 1:
The locking mechanism is segmented into separate locking systems for each blade member (first locking mechanism for the first blade member, second locking mechanism for the second blade member). This segmentation isolates potential failure points, so that if one locking mechanism experiences issues, the other can still maintain blade stability, thereby enhancing overall reliability despite the increased complexity of having dual locking systems.
Solution Approach 2:
The locking mechanisms are designed to automatically engage and disengage through the natural folding and unfolding motions of the blade members. The spring-loaded or cam-based locking systems self-activate when the blade reaches its extended or retracted positions, reducing the need for complex manual operation and minimizing user error, thus maintaining reliability.
Data Source
AI summary
A knife includes a handle, a first blade member which is foldable about a first pivot located near or on the handle, and a second blade member foldable about a second pivot located in the first blade member.