Hair-Cutter External Blade Profiled Base Stiffness
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Solution Overview
Problem
Reducing the sheet thickness of the external cutting member in hair-cutting appliances leads to vibrations that can produce a noticeable sound due to the frequency of these vibrations approaching the eigenfrequency of the external cutting member.
Innovation Solution
The design of the external cutting member is modified by incorporating a profiled section in the annular base portion, which alters its stiffness, thereby adjusting the eigenfrequency and reducing the likelihood of vibrations producing a noticeable sound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the sheet thickness of the external cutting member is reduced, then the weight and material consumption are decreased, but the eigenfrequency changes causing noticeable sound production during operation
Solution Approach 1:
The patent applies local quality by modifying only the annular base portion of the external cutting member while leaving the rest of the structure unchanged. The profiled section with bent connection zones is introduced locally to alter stiffness characteristics without changing the overall sheet thickness or other structural elements, thereby addressing the sound production issue specifically in the critical area.
Solution Approach 2:
The patent employs parameter changes by modifying the geometric parameters of the annular base portion through the introduction of a profiled section. The bent connection zones change the local stiffness parameter, which in turn adjusts the eigenfrequency of the external cutting member to prevent resonance and reduce sound production during operation.
2Ease of manufacture
If the sheet thickness is reduced to minimize material usage, then manufacturing cost decreases, but vibrations approach the eigenfrequency causing audible noise
Solution Approach 1:
The solution introduces a profiled section with bent connection zones specifically in the annular base portion, applying local structural modification rather than changing the entire external cutting member design. This localized approach maintains manufacturing simplicity while effectively addressing the vibration and sound issue.
Solution Approach 2:
The profiled section incorporates curved bent connection zones that replace straight transitions. This curvature modification alters the stiffness distribution in the annular base portion, adjusting the eigenfrequency to prevent resonance with operational vibrations, thereby reducing sound production.
3Device complexity
If a thinner sheet is used for the external cutting member, then device complexity and material usage are reduced, but the eigenfrequency shifts causing noticeable sound during hair-cutting action
Solution Approach 1:
The patent maintains device simplicity by introducing only a profiled section with bent connection zones in the annular base portion. This minimal local modification does not increase overall structural complexity while effectively addressing the sound production problem caused by eigenfrequency shifts in thinner sheets.
Solution Approach 2:
The bent connection zones in the profiled section introduce curvature elements that modify the stiffness characteristics of the annular base portion. This geometric modification adjusts the eigenfrequency to prevent resonance with operational vibrations, reducing sound without complicating the overall device structure.
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 change effectively reduces or increases the eigenfrequency of the external cutting member, preventing vibrations from producing an undesirable sound, even when using thinner sheets, without compromising hair-cutting performance.
Implementation Method 1
The design of the external cutting member is modified by incorporating a profiled section in the annular base portion, which alters its stiffness, thereby adjusting the eigenfrequency and reducing the likelihood of vibrations producing a noticeable sound
Implementation Method 2
Reducing the sheet thickness of the external cutting member in hair-cutting appliances leads to vibrations that can produce a noticeable sound due to the frequency of these vibrations approaching the eigenfrequency of the external cutting member
Data Source
AI summary
In an external cutting member (10) which is configured to be used in a hair-cutting unit in combination with a rotatable internal cutting member, a base (11) includes at least one hair-cutting track (21) which is provided with a plurality of hair-entry openings, and an annular base portion (31) located between a central portion (17) of the base (11) and an innermost one of the at least one hair-cutting track (21). The annular base portion (31) is provided with a profiled section which is located between a straight inner section (32) and a straight outer section (33) of the annular base portion (31), which is annular about a central axis (16) of the external cutting member (10), and which is shaped according to a predefined profile, seen in a cross-section of the external cutting member (10) comprising the central axis (16).