Raised Outer Boundary Section for Electric Shaver Under Cutter
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Solution Overview
Problem
Existing electric shaving apparatuses with under cutters having cutting edges of less than 90° suffer from skin irritations due to interactions with the skin arching into the shearing apertures of the outer cutter, while those with 90° cutting edges provide better skin protection but may cause injuries with sharp edges.
Innovation Solution
The under cutter blade features a raised outer boundary section that inclines upward toward the outer cutter, with a blade angle between the direction of movement and the outer leg of the cutting edge ranging from 20° to 1°, ensuring mechanical stability and minimizing skin irritation, and a cutting edge radius of 2 μm or less for optimal shaving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the under cutter uses sharp-edged blades with a cutting edge angle of less than 90°, then the cutting forces are reduced and stroking action is improved, but skin irritations occur due to the skin arching into the shearing apertures of the outer cutter
Solution Approach 1:
The raised outer boundary section of the blade creates a preliminary protective barrier that prevents the skin from arching into the shearing apertures before the cutting action occurs. This preliminary geometric configuration counteracts the harmful skin arching effect that would otherwise occur during shaving with sharp-edged blades.
Solution Approach 2:
The blade design applies different geometric properties to different regions: the cutting edge maintains a sharp angle of less than 90° for effective hair cutting, while the outer boundary section is raised to create a protective profile. This local differentiation allows the blade to simultaneously achieve low cutting forces and prevent skin irritations.
2Object-affected harmful factors
If the under cutter uses cutting edges with a cutting angle of 90°, then skin protection is optimized, but the stroking action and cutting efficiency are reduced
Solution Approach 1:
The blade design applies different geometric properties to different regions: the cutting edge maintains a sharp angle of less than 90° for effective hair cutting, while the outer boundary section is raised to create a protective profile. This local differentiation allows the blade to simultaneously achieve low cutting forces and prevent skin irritations.
3Productivity
If the under cutter is equipped with sharp-edged blades, then thorough shaving is achieved by capturing and shortening even the shortest hairs, but skin irritations and injuries occur
Solution Approach 1:
The raised outer boundary section of the blade creates a preliminary protective barrier that prevents the skin from arching into the shearing apertures before the cutting action occurs. This preliminary geometric configuration counteracts the harmful skin arching effect that would otherwise occur during shaving with sharp-edged blades.
Data Source
AI summary
A shaving head for an electric shaving apparatus, having an under cutter comprising at least one blade which is drivable in at least one direction of movement relative to an outer cutter. To achieve a good shaving result while at the same time protecting the skin to be best possible effect, it is proposed providing the blade with an outer boundary section which is raised in relation to the cutting edge, faces in the direction of the outer cutter and inclines upwardly from the cutting edge toward the outer cutter.