Utility Knife Dual Return Mechanism Variable Force
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Solution Overview
Problem
Existing utility knives face challenges in cost-effective production and simple assembly of the return device, with limited variability in return force, which affects user safety and operational efficiency.
Innovation Solution
The utility knife incorporates a dual return mechanism using a spring and movable element with differently oriented contact surfaces, allowing for varying return forces and easy assembly, enabling movement between safety, cutting, and blade-change positions through straight-line, rotary, or mixed movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional return device with a single spring is used, then the structure is simple, but the return force cannot be varied and assembly is not simplified
Solution Approach 1:
The return device is segmented into first return means (spring with movable element) and second return means (counter surface with multiple regions), where each segment contributes differently to the return force in different movement regions, enabling variable return force without requiring multiple springs
Solution Approach 2:
The counter surface is designed with different local qualities (different orientations) in different regions. The first region has a first orientation and the second region has a second orientation, allowing the return force to vary locally depending on which region the movable element contacts during blade holder movement
2Adaptability or versatility
If the return device is designed with multiple components for force variation, then return force can be adjusted, but assembly becomes complex
Solution Approach 1:
The counter surface combines multiple functional regions (first region with first orientation, second region with second orientation) into a single integrated component. This merging allows the return device to provide variable return force through different regions while maintaining simple assembly, as the counter surface acts as one unified part rather than requiring separate components for each function
Solution Approach 2:
The counter surface serves multiple functions: it provides a bearing surface for the movable element, defines different return force characteristics through its different regions, and enables both first return force (in first region) and second return force (in second region). This multi-functionality eliminates the need for separate components for each function, simplifying assembly
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
This design enhances user safety by allowing adjustable return force, simplifies assembly, and improves operational efficiency by enabling smooth transitions between positions without requiring active user force in the return direction.
Implementation Method 1
The return device comprises first return means and second return means. The first return means include a movable element and a spring. The movable element is connected to the spring and is urged in a travel direction by the spring.
Data Source
AI summary
A utility knife has a housing, a blade holder movable between a front position and a rear position in the housing, and first and second return formations of which one is mounted on the housing and the other on the blade holder. The first and second return formations urge the blade holder into the rear position relative to the housing in at least one region of movement of the blade holder. The first return formation includes a spring and a movable element connected to the spring and urged thereby in a travel direction of the movable element. The second return formation includes a counter surface engageable with the movable element.