Retractable Knife Blade Holder Dynamics
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Solution Overview
Problem
Existing knives lack a compact design with enhanced safety, manufacturability, and functionality, particularly in their blade holder mechanisms, which often rely on linear movements and complex interactions that are not easily scalable or cost-effective.
Innovation Solution
A knife design featuring a blade holder that is both translationally and rotatably movable, utilizing a compound movement actuated by a handle and actuating element forming a swivel joint, allowing for a pivoting and linear movement, and incorporating a support element for safe blade retraction and extended cutting positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the blade holder is mounted to move only translationally as in prior art, then the mechanism is simple, but the actuating element is limited to linear movement and cannot achieve compact design with enhanced safety
Solution Approach 1:
The blade holder is mounted on the housing so that it can move in a translational and/or rotatable manner. The actuating element is connected to the blade holder by a swivel joint, allowing the actuating element to perform complex movements including pivoting and translational components, transforming the restricted linear movement into dynamic multi-directional movement capability
Solution Approach 2:
The swivel joint connection between the actuating element and blade holder adds rotational freedom to the previously linear actuation path. This enables the actuating element to move from a basic position into a first pivoting position, creating compound movement with both linear and angular components that achieves compact design while enhancing safety
2Adaptability or versatility
If complex movement paths are implemented for the blade holder, then cutting functionality is enhanced, but the number of parts increases and manufacturing costs rise
Solution Approach 1:
The swivel joint combines multiple movement functions (pivoting and translational) into a single connection element between the actuating element and blade holder. This merging of movement capabilities into one joint reduces the number of separate parts needed compared to implementing complex movement paths through multiple separate mechanisms
Solution Approach 2:
The actuating element serves multiple functions: it pivots from basic position to first pivoting position to move the blade holder from safety position to first cutting position, and can further move to second pivoting position for second cutting position. This multi-functionality in a single element achieves enhanced cutting capability without proportionally increasing part count
3Productivity
If the blade is always accessible for cutting, then cutting efficiency is high, but safety is compromised when the blade protrudes from the housing
Solution Approach 1:
The blade holder is dynamically positioned between a safety position (blade retracted into housing) and cutting positions (blade protruding). The actuating element connected via swivel joint enables controlled transition between these states, allowing the blade to be accessible only when needed while maintaining safety when retracted
Solution Approach 2:
The actuating element serves as an intermediary mechanism that controls blade accessibility. By pivoting from basic position to first pivoting position, it mediates between the safe retracted state and the active cutting state, ensuring the blade is exposed only when deliberately actuated
Data Source
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AI summary
The retractable-blade utility knife (10) has slide (12) which shiftable on the housing (11) between the advanced and retracted positions. A pawl (33) is shiftable between engaged position braced between blade holder (13) and housing in first cutting position and disengaged position out of engagement with blade holder or housing in second cutting position, in which in engaged position the pawl holds the blade in first cutting position while in second cutting position pawl is disengaged and tension spring (19) returns holder to safety position.