Bladed Tool Shank Retention via Bent Tang
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Solution Overview
Problem
Existing bladed tools, such as taping knives and putty knives, require significant amounts of metal for the blade-retaining shank and polymeric material for the handle core, leading to increased weight and manufacturing costs.
Innovation Solution
A bladed tool design featuring a blade with a surface-engaging edge and a handle that includes a shank-retaining slot with a bend to prevent forward movement of the shank, minimizing material usage by incorporating a hollow interior access channel and using shank tangs with a wedged bulkhead to secure the shank during fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional solid polymeric handle core with a long metal shank is used, then blade retention is reliable, but the tool weight and material cost increase significantly
Solution Approach 1:
The handle core is segmented into a hollow structure with an interior access channel running through it, rather than being a solid polymeric mass. This segmentation reduces the amount of polymeric material needed while maintaining the structural integrity required for blade retention through the shank-retaining slot and bend mechanism.
Solution Approach 2:
The interior access channel is extracted from the solid handle core, creating a hollow passage that reduces material usage. This channel allows access to the shank bend for potential blade replacement while removing unnecessary polymeric material that would otherwise be required for blade retention.
2Reliability
If a long metal shank extending through the entire handle length is used, then the blade is securely retained, but the amount of metal required and manufacturing cost increase
Solution Approach 1:
The shank is extracted from the handle at a point forward of the handle's rear end, eliminating the need for the metal shank to extend through the entire handle length. The shank-retaining slot and bend mechanism are positioned to provide secure retention without requiring the shank to span the full handle length, thus reducing metal quantity.
Solution Approach 2:
Instead of relying solely on the shank length (one-dimensional solution), the invention uses a bend in the shank combined with a shank-retaining slot to create a two-dimensional retention mechanism. The bend provides mechanical interlocking with the slot, offering reliable blade retention without increasing shank length or metal quantity.
3Quantity of substance
If a hollow handle core with an interior access channel is used, then material usage is reduced, but the structural complexity of the handle increases
Solution Approach 1:
The handle core is segmented into a hollow structure with an interior access channel, which reduces polymeric material usage. The segmentation creates distinct functional zones: the hollow core for material reduction, the access channel for blade replacement access, and the shank-retaining slot for blade fixation, balancing complexity with material efficiency.
Data Source
AI summary
A bladed tool includes a handle and a blade with a surface-engaging edge and a blade-retaining shank. The handle includes an elongated handle body having longitudinally opposed body front and rear ends, and at least one side wall extending between the body front and rear ends. The side wall defines an outer surface configured for gripping by a user and an inner surface that defines an interior access channel extending from an access opening in the body rear end toward a forward channel wall located to the rear of the body front end. Situated between the body front end and the forward channel wall is a handle core that defines a shank-retaining slot extending between a forward slot-opening in the body front end and a rearward slot-opening in the forward channel wall. The shank extends rearwardly through the shank-retaining slot such that a protruding shank portion extends to the rear of the forward channel wall. Forward movement of the shank relative to the handle body is prevented by bending the shank rearward of the forward channel wall.