Hand-Operated Tool Crisscross Fittings Cam Contact

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Solution Overview

Problem

Conventional hand-operated tools lack optimal force distribution throughout the cutting or pressing operation, requiring excessive force at the beginning and reducing operability due to heavy designs with long handles, making them inconvenient for one-handed use, especially in applications like cutting electrical cables or attaching terminals.

Innovation Solution

A hand-operated tool with a novel structure featuring cam contact surfaces and crisscross connection fittings that maintain constant or varying pressure by adjusting pivot pin locations, allowing for uniform force application from the initial to the final stage of cutting or pressing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If long handles are used to increase cutting pressure, then the pressure applied to the blades is increased, but the tool becomes heavier and less convenient to carry and operate

Engineering Contradiction:
Improvecutting pressureVSAvoidtool weight
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The patent changes the geometric parameters of the toggle mechanism, specifically the distance between the pivot and the center axis. By optimizing this distance, the mechanism generates sufficient cutting force without requiring excessively long handles, thus avoiding increased tool weight while maintaining effective cutting pressure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a movable pivot that can be adjusted to different positions along the handle. This dynamic adjustment allows the user to optimize the toggle mechanism's mechanical advantage for different cutting stages, achieving high cutting force without permanently increasing the handle length or tool weight.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If the pivot distance from center axis is constant, then the structure is simple, but the cutting force is insufficient at the beginning of cutting operation

Engineering Contradiction:
Improvestructure simplicityVSAvoidcutting force
Core Design Contradiction:
Device complexityVSForce

Solution Approach 1:

The patent makes the pivot position dynamic rather than fixed. The pivot can be adjusted to different locations on the handle, allowing the toggle mechanism to generate sufficient cutting force at different stages of the cutting operation while maintaining overall structural simplicity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent segments the handle into multiple sections with the pivot positioned at adjustable locations. This segmentation allows the mechanism to optimize the force generation at different phases of cutting without complicating the overall structure.

Inventive Principle:
Principle #1Segmentation

3Duration of action of moving object

If the cutting force increases gradually, then the force distribution is linear, but large force is not available from the initial stage of cutting

Engineering Contradiction:
Improveforce distribution patternVSAvoidinitial cutting force
Core Design Contradiction:
Duration of action of moving objectVSForce

Solution Approach 1:

The patent uses a movable pivot that can be positioned to change the mechanical advantage throughout the cutting stroke. By adjusting the pivot position, the mechanism can provide high initial cutting force when needed, rather than relying on gradual force increase, while maintaining reasonable force distribution throughout the operation.

Inventive Principle:
Principle #15Dynamics

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 achieves optimal pressure distribution, maintaining constant or varying force levels as needed, enhancing usability and reducing weight, thus improving operability for cutting steel wires, coated cables, and attaching terminals.

Implementation Method 1

the opposing surfaces thereof form cam contact surfaces in a certain arc form that directly make contact with each other

Methodology Applied
Scientific EffectCam mechanism: Cam

Data Source

PatentEP2656981B1Hand-operated tool
Publication Date: 2016.06.22 MINORU IND
  • EP2656981B1 patent drawingFigure 1
  • EP2656981B1 patent drawingFigure 2
  • EP2656981B1 patent drawingFigure 3~4

AI summary

In order to provide a hand-operated tool configured to allow production of the tool with the optimal handle action for the intended use by changing the positions where the pivot pins penetrate and the setting of the connection fittings, the tool is provided with a pair of right and left cutting blades (1, 1), a pair of right and left operating handles (3, 3) connected to said blades (1, 1) via pivots (2, 2), and connecting pins (4) that connect the blades (1, 1) to each other, and is configured so that: the operating handles (3, 3) are disposed so as to abut in the same plane and the opposing surfaces (31, 31) thereof form cam contact surfaces (32, 32) that directly contact each other; between the pivots (2, 2) and the pivot pins (6, 6) of the other operating handles (3, 3), two connection fittings (7, 7) that connect the right and left handles (3, 3) on the front and back surfaces are disposed diagonally in a criss-cross shape, connecting the respective upper and lower ends (7a, 7b) to the pivots (2, 2) and the pivot pins (6, 6); and the criss-cross position of the connection fittings (7, 7) is determined by the positioning of the pivot pins (6, 6).