Razor Blade Coating Tip Geometry for Cutting Force and Durability

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Solution Overview

Problem

Existing razor blades face a trade-off between durability and cutting force, where increasing the thickness of the coating layer to enhance durability also increases the cutting force, and vice versa.

Innovation Solution

The razor blade features a coating layer with a specific shape in the tip region, including a pair of coating facets and a coating tip, where the vertical distance between a straight line connecting the wedge points and the coating tip ranges from 0.5 to 1.5 micrometers, optimizing both durability and cutting force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness of the coating layer is increased to enhance durability, then the durability is improved, but the cutting force increases

Engineering Contradiction:
ImprovedurabilityVSAvoidcutting force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The coating layer is designed with different thicknesses in different regions: the tip region has a controlled thickness (0.5-1.5 micrometers) to maintain low cutting force, while the root region has increased thickness for durability. This local differentiation resolves the contradiction by optimizing each region for its specific function.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention transitions from considering only the vertical thickness of the coating layer to incorporating horizontal dimension considerations by defining specific geometric parameters (wedge points, virtual points, and their vertical distances) to control the coating shape, thereby achieving both durability and low cutting force through multi-dimensional optimization.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Force

If the substrate is made thinner to reduce cutting force, then the cutting force decreases, but the durability decreases

Engineering Contradiction:
Improvecutting forceVSAvoiddurability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The substrate is designed with a thin tip region for low cutting force and a thicker root region for durability. The coating layer thickness is locally adjusted to compensate: thinner at the tip to maintain sharpness, thicker at the root to protect the thinner substrate, thereby resolving the contradiction between thin substrate and durability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention uses a composite structure of substrate and coating layer, where the coating material compensates for the reduced substrate thickness. The combination allows the overall structure to achieve both the low cutting force of a thin substrate and the durability of a thicker protective layer.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4556182A1Razor blade
Publication Date: 2025.05.21 DORCO CO LTD
  • EP4556182A1 patent drawingFigure 1
  • EP4556182A1 patent drawingFigure 2
  • EP4556182A1 patent drawingFigure 3A

AI summary

According to one embodiment of the present disclosure, there is provided a razor blade comprising: a substrate; and a coating layer laminated on the substrate and having a coating tip formed on an end portion, characterized in that: the coating layer comprises a pair of coating facets extending from the coating tip, the pair of coating facets comprise: a pair of first coating facets each having one end forming the coating tip; and a pair of second coating facets each connected to the other end of each of the pair of first coating facets, a vertical distance between a straight line connecting the pair of wedge points and the coating tip ranges from 0.5 to 1.5 micrometers.