Razor Blade Unit with Positioning Notches and Elastic Cover
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Solution Overview
Problem
Conventional razor blade units with multiple blades face challenges in maintaining precise positioning of cutting edges and efficient assembly, as rivets become impractical due to increased blade width and separate frame parts requiring tight tolerances, leading to potential user injury and suboptimal shaving results.
Innovation Solution
The razor blade unit incorporates positioning notches in the housing and an elastic cover component to securely hold the blades' cutting edges, compensating for manufacturing tolerances and ensuring precise alignment with minimal components and assembly steps, while using angled blades for effective rinsing and a sacrificial aluminum anode for corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If blades are fastened to the frame using rivets, then the blades can be securely held in position, but the distance between rivet holes and cutting edge increases significantly with each additional blade, requiring different blade geometries and leading to very wide cutting units
Solution Approach 1:
The invention extracts the blade fastening function from the frame structure and relocates it to the housing slots and metal clips. The blades are no longer riveted to the frame but are instead held by clips within the housing, separating the support function from the cutting function and allowing compact blade arrangement.
Solution Approach 2:
The blades are nested within the housing structure, with multiple blades arranged in slots inside the housing cavity. This nesting allows multiple blades to be contained within a compact volume, reducing the overall cutting unit width while maintaining secure fastening through the clip mechanism.
2Ease of manufacture
If the foam edge and slide strip are located on different frame parts, then the components can be manufactured separately, but the parts determining the skin contact plane must lie within very narrow tolerances with respect to their positioning
Solution Approach 1:
The foam edge and slide strip are merged into a single integrated housing structure, with both components positioned relative to a common reference plane. This integration eliminates the need for tight tolerances between separate frame parts, as all skin-contact components are now referenced to the same housing structure.
Solution Approach 2:
The housing serves as an intermediary structure that positions both the foam edge and slide strip relative to a common reference plane. This intermediary housing absorbs positioning tolerances, allowing the foam edge and slide strip to be manufactured separately while maintaining accurate relative positioning through the housing's reference features.
3Quantity of substance
If the number of blades in the razor blade unit is increased, then the shaving coverage is improved, but the positioning precision of cutting edges becomes more difficult to maintain
Solution Approach 1:
The housing is segmented into multiple slots, each with its own positioning notch and metal clip assembly. This segmentation allows each blade to be independently positioned and secured, maintaining precise cutting edge alignment even with multiple blades. Each slot acts as an independent positioning unit, preventing cumulative positioning errors.
Solution Approach 2:
The positioning mechanism is copied for each blade, with identical positioning notches and metal clip assemblies repeated in each slot. This replication ensures consistent positioning precision across all blades, as each blade is subjected to the same positioning constraints rather than relying on cumulative tolerances from a single reference.
4Strength
If conventional metal retaining clips are used to secure the blades, then the blades can be held in position, but the assembly process requires multiple steps including positioning the U-shaped clip over the housing and bending the side pieces
Solution Approach 1:
The metal clips are pre-formed with bent side pieces during manufacturing, eliminating the need for post-assembly bending operations. The clips are delivered in their final configuration, ready to be simply positioned over the housing and blades, reducing the assembly process to a single placement step.
Solution Approach 2:
The metal clips are designed to be self-installing, where the bent side pieces automatically engage with the housing and blades upon placement. The clips perform their own fastening function without requiring external tools or additional assembly operations, making the process simple and tool-free.
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
This design ensures precise blade positioning, reduces assembly complexity, and lowers production costs, ensuring safe and optimal shaving performance with easy maintenance and corrosion protection.
Implementation Method 1
the cover to comprise an elastic component, where this elastic component exerts a force on the back edges of the blades and thus presses the cutting edges of the blade into the positioning notches
Implementation Method 2
a sacrificial aluminum anode for corrosion protection
Data Source
AI summary
A razor blade unit including a blade housing to hold at least one blade with a cutting edge, and a cover connected to the blade housing. The cover faces the back edges of the blades, i.e., the edges opposite from the cutting edges. The blade housing has positioning notches to support the cutting edges. In addition, the cover can have recesses to support the back edges of the blades and an elastic component, which exerts a pressing force on the back edges of the blades.