Self-Retracting Knife With Undulated Surface Actuator
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Solution Overview
Problem
Existing utility knives either offer a plurality of predefined blade-extension positions or self-retraction, but not both simultaneously, limiting their versatility in cutting tasks.
Innovation Solution
A self-retracting knife design that incorporates a handle body with an actuator slot and undulated surfaces, allowing for selective blade protrusion positions and automatic retraction, facilitated by a resilient thumb button and biasing mechanism, enabling both predefined blade extensions and self-retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a utility knife is designed with a plurality of predefined blade-extension positions, then cutting depth control is improved, but the ability to achieve automatic retraction after cutting is lost
Solution Approach 1:
The knife transitions from static predefined positions to a dynamic system where the blade can be extended to any position during cutting and then automatically retracts. The resilient button and biasing mechanism enable continuous position adjustment during use, followed by automatic return to retracted position, combining the benefits of both predefined positions and self-retraction.
Solution Approach 2:
The system changes the operational parameters of blade extension from discrete predefined positions to a continuous range of positions during cutting, with automatic reset to a default retracted position. This allows users to select appropriate blade exposure for different cutting tasks while ensuring safety through automatic retraction.
2Object-affected harmful factors
If a utility knife is designed as self-retracting with automatic blade retraction, then safety is improved, but the ability to select multiple blade-extension positions for varying cutting depths is lost
Solution Approach 1:
The knife transitions from static predefined positions to a dynamic system where the blade can be extended to any position during cutting and then automatically retracts. The resilient button and biasing mechanism enable continuous position adjustment during use, followed by automatic return to retracted position, combining the benefits of both predefined positions and self-retraction.
Solution Approach 2:
The biasing mechanism and resilient button enable the blade to automatically retract to a safe position after cutting without user intervention, while still allowing users to extend the blade to appropriate positions for different cutting depths during use. The system serves itself by automatically returning to safety position.
3Ease of operation
If the thumb button is normally biased outwardly toward the housing exterior for engagement into predefined positions, then position selection is improved, but the mechanism complexity increases
Solution Approach 1:
Instead of biasing the button outwardly for position selection, the system inverts the approach by biasing the blade slide inwardly toward retraction. The button is only pressed inwardly during cutting to extend the blade, and releases automatically. This simplifies the mechanism by eliminating the need for multiple button positions and complex biasing systems.
Solution Approach 2:
The system extracts the complex multi-position button mechanism and replaces it with a simpler single-action button that works in conjunction with a biasing mechanism. The button's only function is to overcome the biasing force during cutting, after which automatic retraction occurs, reducing overall mechanism complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The knife provides users with the ability to choose from multiple blade protrusion positions for varying cutting depths while ensuring automatic retraction after use, enhancing cutting efficiency and safety.
Implementation Method 1
the blade slide is normally biased toward a retracted position... a biasing mechanism, enabling both predefined blade extensions and self-retraction
Implementation Method 2
a resilient thumb button and biasing mechanism, enabling both predefined blade extensions and self-retraction
Implementation Method 3
Friction between the blade and the material to be cut retains the blade in an extended position in opposition to the biasing force
Data Source
AI summary
A knife includes a handle body defining an interior blade-slide cavity housing a blade slide carrying a blade with a cutting edge. The blade slide is reciprocated within the blade-slide cavity between a blade-storage position in which the cutting edge is housed within the handle body and at least two blade-protruding positions in which the cutting edge protrudes to the exterior of the handle body, through a forward-end opening, to disparate extents. Blade-slide reciprocation is facilitated by a blade-slide actuator that includes a button reciprocable along an actuator slot defined through the handle body. A handle-body undulated surface defined along the handle body in the vicinity of the actuator slot is configured for selective mechanical interference with a button undulated surface in order to define the at least two blade-protruding positions. A blade-protruding position is temporarily maintained through a user's depression of the button to maintain the selective interference.