Brush Stem Elastomeric Sheath for Mold Gap Sealing
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Solution Overview
Problem
Existing brush-like devices for interdental cleaning and cosmetic applications face issues with mold adaptation to twisted metal wire stems, leading to tolerance gaps, burr formation, and loss of elasticity due to traditional molding methods, which affect the brush's functionality and aesthetics.
Innovation Solution
A manufacturing method involving an elongated elastomeric or high-density foam sheath applied to the tang of the brush stem, which fills gaps and provides a seal between the stem and the mold, maintaining elasticity and preventing burr formation, while being easy to apply and center within the mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the tang is embedded in the handle head by traditional molding methods, then the manufacturing process is simple, but tolerance gaps form between the stem and mold seat leading to burr formation
Solution Approach 1:
The patent applies a flexible deformable ring (gasket) made of elastomeric material that can deform under injection pressure to conform to the irregular twisted wire stem surface, filling tolerance gaps and preventing burr formation while maintaining manufacturing simplicity
Solution Approach 2:
The deformable ring acts as an intermediary element between the mold seat and the tang stem, mediating the interface to eliminate gaps caused by tolerance variations while allowing the simple traditional molding process to continue
2Manufacturing precision
If the mold seat strongly clamps the brush stem to eliminate gaps, then burr formation is prevented, but the metal wires harden and lose resiliency
Solution Approach 1:
The flexible deformable ring provides the necessary clamping force to eliminate gaps and prevent burrs, while its elastomeric nature allows it to deform and release pressure, preventing permanent hardening of the metal wire stem
Solution Approach 2:
The ring material properties (elastomeric, deformable) are specifically chosen to allow temporary parameter changes during molding (compression) that revert after molding, preserving the stem's resiliency while achieving gap elimination during the critical molding phase
3Manufacturing precision
If a deformable ring gasket is added to seal the mold, then burr formation is prevented, but the device complexity increases
Solution Approach 1:
The deformable ring is a simple elastomeric component that can be pre-mounted on the tang or inserted into the mold, providing effective sealing without complex construction or additional manufacturing steps
Solution Approach 2:
The gasket is a simple, inexpensive elastomeric ring that can be easily replaced if needed, and its simplicity means it adds minimal complexity to the overall device construction
4Length of moving object
If the tang extension is made short for aesthetics and function, then the device is more compact, but the stem cannot be properly supported during molding
Solution Approach 1:
The deformable ring provides adequate support for short tang extensions by conforming to the stem surface and distributing molding pressure, enabling both compact design and reliable molding of shortened stems
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 solution effectively seals the mold, prevents burr formation, maintains the brush's elasticity, and enhances aesthetics by hiding the stem, ensuring a secure and functional brush assembly.
Implementation Method 1
an elongated covering sheath 5 of elastically yielding material is applied, which fills at least partially the gaps between the cylindrical surface of the seat T' and the surface of the stem 4
Implementation Method 2
from the external part, to sufficiently deform to remain in seal coupling with the surface of the seat T' of the mould
Data Source
Figure 1~2
Figure 2A~7A
Figure 3~3a
AI summary
It is disclosed a brush-like device and related manufacturing method, wherein the device comprises at least a handle head portion (2) obtained by means of plastic mate- rial moulding on a terminal portion of a metal stem (4) on which bristles of the brush are fixed, said terminal portion of the stem (4) being retained in the moulding position by a through seat (Τ') of a mould (T) which closes on said stem, and wherein, prior to said moulding of the head portion (2), it is provided to apply a covering sheath (5) of elastically yieldable material on said terminal portion of the stem (4), said sheath being of elongate tubular shape having a length of at least 2.5 mm.