Shear Foil Lower Cutter Geometry for Dense Blade Shaving
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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 leads to bending stresses and potential cracking, limiting the number of cutting actions per unit time.
Innovation Solution
A lower cutter design with a dense arrangement of blades, each spaced 0.80 to 0.95mm apart, 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 large 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 unit time, then cutting efficiency is improved, but the blades become narrower and less rigid, leading to bending stresses and potential cracking
Solution Approach 1:
The lower cutter is divided into multiple individual blades instead of a single continuous cutting edge. This segmentation allows each blade to be optimized independently - narrow enough to allow close spacing for high cutting efficiency, yet structurally complete enough to maintain adequate rigidity and resist bending stresses during operation
Solution Approach 2:
The blade design incorporates varying local properties: the cutting edges are sharp and narrow for effective hair cutting, while the blade bases and root sections have increased thickness and structural reinforcement to provide the necessary rigidity and resist bending stresses, creating a gradient of structural quality along the blade length
2Productivity
If the gap between neighboring blades is reduced to increase blade density, then cutting efficiency is improved, but the blade width must be reduced, compromising blade strength and rigidity
Solution Approach 1:
The blade structure utilizes the third dimension (blade thickness perpendicular to the cutting edge) to compensate for reduced blade width. By increasing blade thickness at critical locations such as the base and root sections, the design maintains adequate structural integrity and rigidity even when blade width is reduced to achieve closer spacing and higher blade density
3Productivity
If the lower cutter reciprocates at higher speed to increase cutting actions, then productivity is improved, but the resonant frequency of the spring system limits the maximum achievable frequency
Solution Approach 1:
The design changes the structural parameters of the cutter system, particularly the blade density and distribution pattern, to optimize cutting efficiency at achievable reciprocating frequencies. By increasing blade density through segmentation and optimal spacing, the system achieves higher productivity without requiring excessive reciprocating speed that would encounter resonant frequency limitations
Data Source
Figure 1
Figure 2a~2b
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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,