Razor Handle Cam Mechanism for Cartridge Pivoting
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Solution Overview
Problem
Existing shaving devices with pivotally connected razor cartridges face challenges in maintaining optimal contact with non-planar skin surfaces due to inadequate biasing forces, which can lead to cartridge chatter or restricted movement during shaving.
Innovation Solution
A handle design featuring a bifurcated biasing member with a partially cylindrical cam surface and shell bearings, along with protective fins and shields, provides improved pivoting characteristics and secure mounting of the razor cartridge, allowing for resilient movement and preventing 'end over end' rotation, while also offering manufacturing advantages through two-shot injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bias force provided by the biasing member is increased to prevent cartridge chatter, then the reliability of shaving performance is improved, but the ease of operation deteriorates as pivotal movement of the cartridge is restricted
Solution Approach 1:
The cam surface is designed with varying radius of curvature that changes during the pivoting motion. The radius is smaller near the neutral position to provide higher biasing force and prevent chatter, and larger near the extreme position to reduce resistance and facilitate smooth pivoting. This dynamic geometric variation allows the biasing force to adapt automatically to the operational requirements at different positions.
Solution Approach 2:
The geometric parameters of the cam surface, specifically the radius of curvature, are varied along its length to change the mechanical characteristics during motion. This parameter variation enables the system to provide different levels of biasing force at different stages of pivoting, resolving the contradiction between maintaining stability and enabling movement.
2Ease of operation
If the bias force is reduced to allow free pivotal movement, then the ease of operation is improved, but the reliability deteriorates as cartridge chatter occurs during shaving
Solution Approach 1:
The cam surface geometry dynamically adjusts the biasing force during pivoting. The varying radius of curvature ensures that sufficient biasing force is maintained to prevent chatter while allowing smooth movement, eliminating the need to choose between stability and ease of operation.
3Reliability
If the cam surface radius of curvature is small, then the biasing force is increased to prevent chatter, but the device complexity increases due to manufacturing precision requirements
Solution Approach 1:
The radius of curvature parameter is strategically varied along the cam surface to achieve the desired biasing force characteristics. By carefully selecting and varying this geometric parameter, the design achieves effective chatter prevention while maintaining manufacturability through controlled geometric variation.
4Reliability
If the biasing member is made more robust to prevent chatter, then the strength is improved, but the device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
Instead of increasing the robustness of the biasing member structure, the invention achieves chatter prevention by varying the geometric parameters of the cam surface. This approach maintains structural simplicity while achieving the desired functional performance through intelligent geometric design.
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
The handle ensures improved connection and pivoting performance of the razor cartridge, enhancing shaving experience by maintaining optimal blade contact and providing manufacturing benefits through enhanced structural stability and protection during assembly and handling.
Implementation Method 1
The handle is customarily provided with a biasing member that interacts with the razor cartridge to provide an at-rest position and to permit resilient pivotal movement of the razor cartridge away from the at-rest position in response to forces encountered during shaving
Implementation Method 2
The biasing member has a first end integrally coupled with the handle and a second end having a cam surface
Data Source
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Figure 3
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AI summary
Abstract A safety razor has a handle and a razor cartridge. The head portion of the handle has a biasing member and connecting structure to pivotally connect to mating connection structure of the cartridge. The cartridge can pivot about a pivot axis. A cam surface of the biasing member interacts with a cam surface of the housing of the cartridge to permit resilient movement of the cartridge away from an at-rest position in response to forces encountered during shaving. The connecting structure of the handle has first and second shell bearings which each have a fin at the inner end. The fin extends towards the pivot axis and a least a portion of the tip of the fin is closer to the pivot axis than any portion of the cam surface of the biasing member. The fin resists rotation of the cartridge about an axis perpendicular to the pivot axis.