Bent Razor Blade Composition for Crack-Resistant Durability
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Solution Overview
Problem
Existing razor blades with bent portions face manufacturing challenges such as cracking and reduced durability due to macro-scale cracks and enhanced ductility requirements, which can lead to breakage and corrosion, compromising performance and safety.
Innovation Solution
A razor blade made from nitrogen alloyed martensitic stainless steel with a specific composition and a bent region, angled between 105 to 130 degrees, and an outer bend radius of 0.2 to 1.5mm, is produced without reheating, maintaining a durable cutting edge hardness of 550 to 640 HV, and is bent using a punch-and-die or swivel bending process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a razor blade is hardened to provide durability, then cutting edge durability is improved, but cracking occurs in the bent region reducing reliability
Solution Approach 1:
The patent applies different material properties to different regions of the razor blade. The cutting edge region is hardened to high hardness (550-640 HV) for durability, while the bent region is kept softer and more ductile to prevent cracking. This is achieved through selective heat treatment or differential alloying, allowing each region to have the optimal properties for its function.
Solution Approach 2:
The patent modifies the chemical composition parameters of the stainless steel to achieve the desired balance between hardness and ductility. Specific ranges of carbon (0.20-0.40%), chromium (12.0-14.0%), and other alloying elements are used to enable the material to be hardened at the cutting edge while remaining crack-resistant in the bent region.
2Reliability
If ductility is enhanced to prevent cracking, then reliability is improved, but cutting edge durability decreases
Solution Approach 1:
The patent applies different material properties to different regions of the razor blade. The cutting edge region is hardened to high hardness (550-640 HV) for durability, while the bent region is kept softer and more ductile to prevent cracking. This is achieved through selective heat treatment or differential alloying, allowing each region to have the optimal properties for its function.
3Volume of moving object
If bend radius is reduced to achieve compact design, then cartridge size is reduced, but cracking risk increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the stainless steel to achieve the desired balance between hardness and ductility. Specific ranges of carbon (0.20-0.40%), chromium (12.0-14.0%), and other alloying elements are used to enable the material to be hardened at the cutting edge while remaining crack-resistant in the bent region.
Solution Approach 2:
The patent applies different material properties to different regions of the razor blade. The cutting edge region is hardened to high hardness (550-640 HV) for durability, while the bent region is kept softer and more ductile to prevent cracking. This is achieved through selective heat treatment or differential alloying, allowing each region to have the optimal properties for its function.
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
The solution effectively prevents cracking and maintains cutting edge durability, allowing for a smaller bend radius and angle while ensuring the razor blade remains durable and resistant to corrosion, enhancing user safety and performance.
Implementation Method 1
The razor blade comprises a martensitic stainless steel provided as a strip and comprising mainly iron and having (by weight): 0.40 to 0.60% Carbon; 0.30 to 0.55% Silicon; 0.70 to 0.90% Manganese; 13.0 to 14.0% Chromium; 0.50 to 1.0% Molybdenum, and Nitrogen in a range 0.03 to 0.2%
Implementation Method 2
The addition of Nitrogen to Alloy 4 advantageously provides a razor blade of desirable ductility wherein the bent portion can beneficially have a smaller outer bend radius with a low bend angle while the razor blade exhibits a relatively desirable cutting edge durability
Data Source
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Figure 2
AI summary
A razor blade has a first and a second portion. The first portion has a cutting edge at an exterior end and is angled relative to the second portion by a bending process. A bent region that can be arcuate is intermediate the first and second portions. The razor blade is manufactured from martensitic stainless steel being mostly iron and having (by weight): 0.40 to 0.60% C; 0.30 to 0.55% Si; 0.70 to 0.90% Mn; 13.0 to 14.0% Cr; 0.50 to 1.0% Mo; and 0.03 to 0.2%, more preferably 0.03-0.1% N.