Concave-Bevel Razor Blade for Low-Force, Durable Shaving

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Solution Overview

Problem

Conventional razor blades face challenges in achieving a balance between sharpness and durability, leading to high cutting forces and discomfort during shaving, with existing designs either compromising on sharpness for mechanical strength or vice versa, and significant friction contributing to these issues.

Innovation Solution

A cutting blade with a blade body comprising a first and second material, featuring a primary convex or straight bevel and a secondary concave bevel, where the primary bevel's wedge angle is greater than the secondary bevel's, reducing cutting forces and enhancing durability by stabilizing the cutting edge, while the secondary bevel's low wedge angle minimizes contact area and friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the cutting edge is made sharper by reducing the wedge angle, then the cutting force is reduced, but the mechanical strength and durability of the cutting edge deteriorates

Engineering Contradiction:
Improvecutting forceVSAvoidmechanical strength of cutting edge
Core Design Contradiction:
ForceVSStrength

Solution Approach 1:

The cutting blade is divided into two functional zones: a first zone with a first wedge angle optimized for cutting performance, and a second zone with a second wedge angle optimized for mechanical strength. This segmentation allows each zone to perform its specific function without compromising the other, resolving the contradiction between sharpness and durability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the cutting blade are given different wedge angles tailored to their specific functional requirements. The first zone has a smaller wedge angle for reduced cutting force, while the second zone has a larger wedge angle for enhanced mechanical strength. This local differentiation of geometric properties resolves the contradiction by optimizing each region for its primary function.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the wedge angle of the cutting blade is reduced to lower cutting forces, then the cutting comfort is improved, but the fragility of the blade increases

Engineering Contradiction:
Improvecutting comfortVSAvoidblade fragility
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The blade is segmented into two zones with different wedge angles, allowing the first zone to provide cutting comfort through a smaller angle while the second zone provides fragility resistance through a larger angle. This segmentation enables both comfort and reliability to be achieved simultaneously.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cutting blade employs a composite geometric structure combining two different wedge angle zones, analogous to composite materials. This composite design integrates the benefits of both small and large wedge angles, achieving both low cutting forces and high resistance to fragility.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4135949B1Cutting blade with a concave bevel and hair removal device
Publication Date: 2024.04.03 GFD GESELLSCHAFT FUR DIAMANTPRODUKTE MBH
  • EP4135949B1 patent drawingFigure 1
  • EP4135949B1 patent drawingFigure 2~3
  • EP4135949B1 patent drawingFigure 4

AI summary

The present invention relates to a cutting blade (1) having a blade body (15) comprising or consisting of a first material (18) and a second material (19) joined to the first material, the cutting blade having a first face (2), a second face (3) opposed to the first face, and a cutting edge (4) wherein the first face comprises a first surface (9) and the second face comprises a primary bevel (5) having a convex or straight cross- sectional shape and a secondary bevel (6) having a concave cross- sectional shape. Moreover, the present invention relates to a hair removal device comprising this cutting blade.