Razor Blade Thickness Gradient for Cutting Force and Durability
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Solution Overview
Problem
Razor blades for cutting hair face challenges in maintaining optimal cutting force and bending durability, with thin cutting edges leading to reduced force requirements but increased bending susceptibility, affecting shaving performance and feel.
Innovation Solution
A razor blade design with a specific thickness profile and facet structure, featuring a thin tip and varying thickness along the cutting edge to balance cutting force and durability, incorporating a metal and lubrication coating for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the cutting edge of the razor blade is made thinner, then the cutting force becomes lower, but the bending durability decreases
Solution Approach 1:
The razor blade employs a non-uniform thickness distribution along its length, with the thinnest section located at the cutting edge (4-10 μm) and progressively thicker sections toward the base (40-60 μm). This local quality variation allows the cutting edge to be sufficiently thin for low cutting force while the base remains thick enough to provide bending durability and structural support.
Solution Approach 2:
The invention transitions from considering only the cutting edge thickness to analyzing the entire thickness profile along the blade length. By introducing the dimensional parameter of position along the blade (distance from cutting edge), the solution optimizes thickness as a function of position, creating a gradient structure that simultaneously achieves low cutting force at the tip and high bending durability at the base.
2Force
If the cutting edge is excessively thin, then less force is required to cut hair, but the razor blade is prone to bending while cutting hair
Solution Approach 1:
The invention specifies precise thickness parameter ranges at different positions: 4-10 μm at the cutting edge, 20-30 μm at the middle section, and 40-60 μm at the base. These parameter changes create an optimized gradient that reduces cutting force while preventing bending through sufficient structural thickness in the support regions.
Solution Approach 2:
The razor blade is effectively segmented into three functional zones based on thickness: the cutting edge zone (thinnest, 4-10 μm) for minimal cutting force, the transition zone (intermediate, 20-30 μm) for gradual structural support, and the base zone (thickest, 40-60 μm) for maximum bending durability. Each segment serves its specific function while contributing to overall blade performance.
Data Source
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AI summary
A razor blade according to an embodiment of the present invention comprises a substrate having a cutting edge formed at the tip thereof, wherein the thickness (T4) of the substrate as measured at a distance of 4µm from the tip has a value of 1.00 to 1.70µm, the thickness (T250) of the substrate as measured at a distance of 250µm from the tip has a value of 44.00 to 60.56µm, preferably 47.5 to 60.56µm, the ratio of T4 to T250 is 0.032 or less, and the rate of increase of the thickness at a first section included in the region spaced 40 to 100µm apart from the tip is less than the rate of increase of the thickness at a second section included in the region spaced 100µm or greater apart from the tip.