Undulating Shaving Guard Projections Reduce Drag
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Solution Overview
Problem
Shaving razors with multiple blades often experience increased drag forces during use, compromising overall performance despite providing a closer shave, due to the additional blades' influence on shaving geometry and skin interaction.
Innovation Solution
A shaving cartridge design featuring a guard with spaced projections and open slots forming a continuous undulating skin contact surface, which manages skin and hair alignment to minimize drag and improve cutting efficiency, while maintaining proper shaving geometry with fixed blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple blades are added to the cartridge, then the closeness of shave is improved, but the drag forces increase and overall performance deteriorates
Solution Approach 1:
The guard is segmented into multiple discrete projections (first projection, second projection, third projection) spaced apart to define separate slots. This segmentation allows each projection to independently manage skin and hair in specific zones, reducing overall drag while maintaining effective blade exposure for close shaving.
Solution Approach 2:
Different projections have different geometries and positions tailored to local requirements. The first projection has a first slot, the second projection has a second slot, and the third projection has a third slot, with each slot configured to optimize hair alignment and skin management in its specific location, thereby reducing drag forces locally while maintaining overall shaving effectiveness.
2Manufacturing precision
If the guard contacts the skin to establish shaving geometry, then blade orientation is improved, but skin drag increases
Solution Approach 1:
The continuous guard surface is segmented into discrete projections with slots between them. This segmentation reduces the total skin contact area compared to a solid guard, thereby reducing drag forces while the projections themselves maintain the necessary shaving geometry through their specific shapes and positions.
Solution Approach 2:
The guard structure functions as a porous or perforated element with open slots between projections. These slots allow skin and hair to pass through or align with minimal resistance, reducing drag forces while the solid portions of the projections maintain the required blade orientation and exposure.
3Ease of operation
If skin stretching elements are added to the guard, then skin management is improved, but device complexity increases
Solution Approach 1:
The skin management function is merged into the structural projections of the guard itself. The projections serve dual purposes: maintaining shaving geometry and managing skin/hair through their geometric configuration and slot definitions, eliminating the need for separate skin stretching elements and reducing overall device complexity.
Solution Approach 2:
The projections serve multiple functions simultaneously: they define slot geometries for hair alignment, contact the skin to establish shaving geometry, and manage skin tension through their spacing and configuration. This multi-functionality eliminates the need for separate skin stretching elements.
Data Source
AI summary
A shaving cartridge (12) with a housing (16), at least one blade (18) mounted to the housing (16), a guard (20) having a plurality of spaced apart projections (30) defining a plurality of open slots, the open slots (36) having a concave lower surface (44) extending between the plurality of projections (30), the projections having a convex upper surface (42) extending generally transverse to the at least one blade (18) from a front face (34) of the guard (20) toward a rearward edge (32) of the guard (20). The upper surface (42) and the lower surface (44) form a continuous undulating skin contact surface that extends along the length of the guard (20) parallel to the at least one blade (18).