Shear Foil Lower Cutter Geometry for Dense Blades and Durability
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Solution Overview
Problem
Existing electric shaver cutter systems face limitations in increasing cutting efficiency and durability due to the narrow width and rigidity of the lower cutter blades, which are prone to bending stresses and cracks under high friction and cutting forces.
Innovation Solution
A lower cutter design with a dense arrangement of blades, evenly distributed along the longitudinal axis, and a U-shaped cross-section with curved end sections, allowing for high cutting efficiency and sufficient strength and rigidity, reducing bending stresses by increasing the height of the end portions and maintaining a wide contact area with the upper cutter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of blades on the lower cutter is increased to achieve more cutting actions per time, then cutting efficiency is improved, but the blades become narrower and more prone to bending stresses and cracks
Solution Approach 1:
The patent applies local quality by varying the blade width along its length - the blades are narrower at the cutting edge to allow more blades and reduce spacing, while being wider at the base to provide structural strength and resist bending stresses. This non-uniform width distribution optimizes both cutting efficiency and blade durability in different locations of the same component.
Solution Approach 2:
The patent resolves the contradiction by transitioning from a two-dimensional view (number of blades across the width) to a three-dimensional solution (varying blade width along the length). By making blades narrower at the cutting edge and wider at the base, the invention adds the dimension of longitudinal variation to solve the conflict between having more blades and maintaining blade strength.
2Productivity
If the blade width is reduced to fit more blades, then cutting efficiency is improved, but the rigidity and strength of each blade deteriorates
Solution Approach 1:
The blades are designed with non-uniform width, being narrower at the cutting edge where space efficiency is critical for achieving more cutting actions, and wider at the base where structural strength and rigidity are most needed to resist bending moments and cutting forces.
Solution Approach 2:
The solution moves from uniform blade width to variable blade width along the longitudinal axis, utilizing the third dimension (length) to compensate for the reduction in width. This dimensional transition allows the blades to maintain sufficient rigidity despite reduced width for higher blade density.
3Productivity
If the reciprocating frequency is increased to achieve more cutting actions per time, then cutting efficiency is improved, but the bending stresses and friction forces on the blades increase causing durability issues
Solution Approach 1:
The variable blade width design concentrates material where stresses are highest - wider at the base to resist bending moments generated during high-frequency reciprocating motion, and narrower at the cutting edge where material is least needed for structural integrity but most needed for spacing efficiency.
Solution Approach 2:
By utilizing the longitudinal dimension of the blade (making it wider at the base rather than uniformly wide), the invention provides additional structural capacity to handle increased stresses from higher reciprocating frequencies without increasing the overall blade footprint or reducing the number of blades.
Data Source
AI summary
The present invention relates to a shear-foil-type cutter system for an electric shaver, said cutter system including an upper cutter having at least one field of perforations and a lower cutter pressed against said upper cutter having a particular dense blade geometry of the lower cutter and large overlap angle with the upper cutter,