Manual Cutting Tool with Variable Curvature Cam Mechanism
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Solution Overview
Problem
Conventional cutting tools, such as cutting pliers and secateurs, are ineffective for cutting large objects due to limited force exertion, resulting in difficulty starting cuts and poor cut quality, and existing solutions like bolt cutters or toggle systems either increase handle length or provide continuous force gearing that is not optimal during cutting.
Innovation Solution
A manual cutting tool with two jaws and rotating cams, featuring variable curvature bearing surfaces and apertures, connection parts, and intermeshing teeth, which allows for controlled torque transmission and gearing down during cutting, enabling efficient cutting of large objects with reduced user force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the length of the handle is increased to multiply force, then the ability to cut larger objects is improved, but the tool moves into a different category (bolt cutters, hedge trimmers) and requires different operational characteristics
Solution Approach 1:
The patent employs a dynamic toggle mechanism that changes the mechanical advantage ratio during the cutting motion. The toggle system allows the tool to provide high force multiplication when needed (during the cutting stroke) while maintaining a compact handle length. The mechanism transitions from a low-mechanical-advantage phase (for easy engagement) to a high-mechanical-advantage phase (for cutting), optimizing both handle length and cutting force capability.
2Force
If a toggle system is used to multiply force, then the ability to cut larger objects is improved, but the force gearing is continuous rather than optimal during cutting
Solution Approach 1:
The toggle mechanism operates in distinct phases: an engagement phase where the user applies initial force, and a cutting phase where the toggle mechanism engages to provide force multiplication. This periodic action allows the tool to optimize force multiplication specifically during the cutting phase rather than continuously, improving cutting efficiency while maintaining manageable handle length.
3Device complexity
If conventional cutting tools are used for large objects, then the tool structure remains simple, but the force exertion is limited and cutting is difficult
Solution Approach 1:
The patent divides the cutting action into two distinct phases using the toggle mechanism: an initial engagement phase and a cutting phase. During engagement, the tool structure remains relatively simple for easy handling. During cutting, the toggle mechanism engages to provide force multiplication, effectively segmenting the operational requirements and allowing a simpler overall structure while achieving high cutting force when needed.
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 tool effectively cuts large objects with less force than conventional tools, providing optimal gearing down during cutting and minimal gearing after the cut, preventing sliding and damage, and is suitable for various materials like metal and wood.
Implementation Method 1
a first cam (50) mounted rotating with respect to the first jaw (10) and comprising a first bearing surface (52) having a first variable curvature and a first aperture (53)
Implementation Method 2
The first cam (50) can also comprise a first set of teeth (51), and the second cam (60) can comprise a second set of teeth (61) configured to intermesh with the first teeth (51) of the first cam (50)
Data Source
AI summary
The invention relates to a manual cutting tool including two jaws each provided with a cutting blade, the two jaws being mounted movable in rotation with respect to a securing system so as to define a closed position and an open position of a cutting area. The tool also includes two cams mounted rotating with respect to the two jaws and each including an aperture, and a bearing surface having a variable curvature, the two bearing surfaces being configured so as to be in permanent connection. The tool includes two connection parts positioned on the axes of rotation of the jaws and configured to connect the cams to the jaws.