Razor Blade Edge Geometry and Coating for Shaving Comfort
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Solution Overview
Problem
Razor blades face a challenge in achieving an optimal balance between shaving comfort and durability, as a thicker edge tip enhances durability but compromises fluidity, while a thinner tip improves fluidity but reduces durability and increases breakage risk.
Innovation Solution
A razor blade substrate with a symmetrical tapering edge and a multi-layer coating system, including a hard coating and a soft coating, is developed, where the substrate thickness varies from 1.30 to 2.00 micrometers near the tip to 41.70 to 47.00 micrometers further away, combined with a grinding process that maintains durability while enhancing fluidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the edge tip is made thicker, then durability and service life are improved, but cutting forces increase and shaving comfort deteriorates
Solution Approach 1:
The blade edge is designed with non-uniform thickness distribution, creating different local properties: a thinner region near the tip for reduced cutting forces and a thicker region further away for enhanced durability. This local variation in geometry allows simultaneous optimization of both shaving comfort and service life.
Solution Approach 2:
The invention transitions from considering only the tip thickness to defining a comprehensive thickness profile across multiple distances from the tip (5μm, 20μm, 40μm, 250μm). By adding dimensional considerations along the blade edge, the solution optimizes both fluidity and durability through controlled thickness variation.
2Force
If the edge tip is made thinner, then cutting forces are reduced and shaving comfort is improved, but the risk of breakage and damage increases
Solution Approach 1:
Different regions of the blade edge are assigned different thickness characteristics: the tip region (5-40μm from tip) is kept thinner for reduced cutting forces, while the base region (250μm from tip) is made thicker for enhanced strength and breakage resistance. This local differentiation resolves the contradiction between fluidity and strength.
Solution Approach 2:
The blade edge is segmented into multiple zones based on distance from the tip, with each zone having optimized thickness characteristics. This segmentation allows independent optimization of cutting performance in the tip region and structural strength in the base region.
3Reliability
If a multi-layer coating system is applied, then durability and wear resistance are improved, but device complexity increases
Solution Approach 1:
A multi-layer coating system comprising a hard coating layer and a soft coating layer is applied to the blade edge. This composite structure combines materials with different properties: the hard layer provides wear resistance and edge strength, while the soft layer reduces friction and improves shaving comfort. The composite approach simultaneously enhances durability and operational performance.
Solution Approach 2:
The coating system modifies the surface properties of the blade edge by introducing layers with different hardness, friction, and wear characteristics. This parameter transformation at the surface level enhances durability and reduces wear without significantly altering the overall blade structure or manufacturing complexity.
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A razor blade having a symmetrical tapering blade edge ending in a blade tip (14"), the razor blade comprising a substrate (10) and a coating covering the substrate, the coating comprising a soft coating (17) and a hard coating (16), the hard coating comprising at least a main layer (16), the soft coating (17) covering the hard coating (16), wherein the substrate (10) has a substrate tip (14) with a thickness comprised between 1.30 micrometers and 2.00 micrometers measured at a distance of 5 micrometers from the substrate tip (14), a thickness comprised between 4.00 micrometers and 6.00 micrometers measured at a distance of 20 micrometers from the substrate tip (14), a thickness comprised between 8.00 micrometers and 11.50 micrometers measured at a distance of 40 micrometers from the substrate tip (14) and a thickness comprised between 41.70 micrometers and 47.00 micrometers measured at a distance of 250 micrometers from the substrate tip (14).