Superelastic Alloy Scissors Blade Elastic Deformation

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Solution Overview

Problem

Conventional scissors, especially medical use scissors, require skilled craftsmanship for shear adjustment to maintain cutting performance, which is challenging due to the need for precise material matching and handling of small blades, leading to inefficiencies and potential blade deformation over time.

Innovation Solution

The use of superelastic and shape memory alloys for the blades, combined with strategically designed grooves and varying thickness, allows for elastic deformation and improved cutting performance without the need for precise shear adjustment, enabling reliable cutting even with curved blades and reducing the reliance on skilled craftsmanship.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional scissors use same-grade materials for both blades with traditional shear adjustment, then initial cutting performance can be optimized, but the blades bend and torsion becomes off over time requiring frequent reconditioning by skilled craftsmen

Engineering Contradiction:
Improvecutting performance stabilityVSAvoidshear adjustment complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters by using superelastic alloy for one blade instead of conventional steel, which fundamentally alters the mechanical properties to enable automatic compensation for blade deformation, eliminating the need for manual shear adjustment

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The superelastic blade automatically compensates for torsion and bending deviations through its elastic properties, making the system self-adjusting without requiring external intervention by skilled craftsmen to maintain cutting performance

Inventive Principle:
Principle #25Self-service

2Adaptability or versatility

If medical scissors have small blade lengths (10-30 mm or even 2 mm), then they become suitable for specialized surgical procedures, but manufacture becomes extremely difficult and relies entirely on craftsman skill

Engineering Contradiction:
Improvesuitability for specialized proceduresVSAvoidmanufacturing difficulty
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies superelastic alloy material to small blades, changing the material parameters to provide sufficient elasticity and durability even at 2 mm blade lengths, enabling manufacture without relying on exceptional craftsman skill

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite construction with superelastic alloy for one blade and conventional material for the other, combining the benefits of elasticity with traditional cutting blade properties to enable specialized small-blade applications

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If scissors blades are made with high hardness and sharpness through heat treatment, then cutting ability is improved, but the blades become more prone to deformation and require frequent reconditioning

Engineering Contradiction:
Improveblade sharpnessVSAvoidblade shape stability
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent changes the material composition to superelastic alloy which provides both the hardness needed for sharp cutting edges and the elastic properties that prevent permanent deformation, resolving the contradiction between sharpness and shape stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The superelastic material inherently cushions against deformation stresses before they can cause permanent damage to the blade shape, preventing the need for reconditioning while maintaining sharpness

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 approach allows for scissors with enhanced durability and sharpness, capable of maintaining cutting performance over time, particularly suitable for medical procedures like neurosurgery, by utilizing materials that deform elastically or return to their original shape, reducing wear and the need for frequent reconditioning.

Implementation Method 1

at least one of the upper shear blade and the lower shear blade is formed by an alloy having an elastic deformation ability of 0.2% or more

Methodology Applied
Scientific EffectSuperelasticity: Pseudoelasticity

Implementation Method 2

The use of superelastic and shape memory alloys for the blades, combined with strategically designed grooves and varying thickness, allows for elastic deformation and improved cutting performance

Methodology Applied
Scientific EffectShape memory effect: Shape Memory Alloy

Data Source

PatentEP3202341B1scissors
Publication Date: 2021.03.31 IMOTT INC
  • EP3202341B1 patent drawingFigure 1(a)~1(c)
  • EP3202341B1 patent drawingFigure 2~3
  • EP3202341B1 patent drawingFigure 4(a)~4(e)

AI summary

The present invention provides scissors obtained by selecting materials sliding against each other, utilizing their springiness, enabling the shape of a blade to be followed so that a shear blade slides against the opposite shear blade, and can cut along the opposite blade. The present invention relates to scissors for medical use comprised of a pair of shanks with one ends forming an upper shear blade and a lower shear blade and with the other ends of the pair of shanks forming handles, the handles being opened and closed centered about a pivot where the shanks intersect and causing the upper shear blade and lower shear blade to open and close, at least one of the upper shear blade and the lower shear blade being formed by an alloy having an elastic deformation ability of 0.2% or more.