Gap-Free Brush Assembly via Plasticized Sacrificial Structures
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Solution Overview
Problem
Conventional methods for manufacturing brushes, such as the AFT process, often leave gaps or cavities between the bristle carrier and the cover part, which can harbor impurities detrimental to hygiene.
Innovation Solution
A method involving a bristle base with through holes and a peripheral edge, combined with a cover part featuring sacrificial structures that are plasticized and welded to fill the gap between the bristle carrier and the cover part, ensuring a gap-free connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional AFT process is used to attach bristle carrier to cover part, then assembly speed is improved, but gaps or cavities remain between the parts which compromise hygiene
Solution Approach 1:
Sacrificial structures are pre-formed on the cover part before assembly. These structures are designed to be plasticized during welding and flow into the gap between the bristle carrier and cover part, filling the void beforehand to prevent impurity accumulation while maintaining quick assembly.
Solution Approach 2:
The sacrificial structures undergo parameter change through plasticization during the welding process. The material transitions from solid to plasticized state, enabling it to flow and fill the gap volume, then solidifies to create a permanent seal that eliminates hygiene concerns while preserving assembly efficiency.
2Object-affected harmful factors
If sacrificial structures are plasticized and pressed to fill the gap volume, then gap-free connection is achieved improving hygiene, but process complexity increases
Solution Approach 1:
The welding process and gap-filling function are merged into a single operation. The sacrificial structures serve dual purposes: providing welding material to join the parts and simultaneously filling the gap volume to eliminate cavities. This integration achieves hygiene improvement without adding separate process steps.
Solution Approach 2:
The sacrificial structures perform multiple functions: they act as welding material source, gap-filling material, and sealant. This multi-functionality eliminates the need for separate gap-filling operations or additional sealing components, maintaining process simplicity while achieving gap-free connection.
3Strength
If peripheral edge and connecting edge are plasticized for welding, then connection strength is improved, but heat may deform outer surfaces of the parts
Solution Approach 1:
Heat application is localized to only the peripheral edge and connecting edge regions that require welding. The outer surfaces are excluded from the plasticization zone, maintaining their original shape and dimensions. This localized heating achieves strong connection without deforming the visible surfaces of the brush body.
Solution Approach 2:
The cover part is functionally segmented into zones: the peripheral edge and connecting edge are designated for plasticization and welding, while the outer surfaces are protected from heat. This segmentation allows differential treatment of different regions, enabling strong joints without surface deformation.
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 method allows for a quick and reliable connection of the bristle carrier and cover part without leaving any gaps or cavities, enhancing hygiene by preventing the accumulation of impurities.
Implementation Method 1
The peripheral edge of the bristle base surrounding the holes and the sacrificial structures of the cover part and its connecting edge are then plasticized by heating
Implementation Method 2
This exclusion can be achieved by means of heat shields, with which radiant heat is kept away
Implementation Method 3
The plasticized mass of the sacrificial structures now flows into the volume which remains between the bristle carrier and the cover part and is bordered by the connecting edge of the cover part and at least largely fills this volume
Implementation Method 4
The plasticized peripheral edge of the bristle carrier is welded to the plasticized connecting edge of the cover part
Data Source
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AI summary
A bristle support is produced from thermoplastic plastics material, having through holes and a peripheral edge surrounding said holes. Brush elements such as bristles, bundles of bristles, cleaning elements made of elastomer material and natural fibres are then fastened in the holes of the bristle support. Furthermore a cover part as a component of a brush body made of thermoplastic plastics material is formed and provided with a mounting region for the bristle support and with sacrificial structures formed in the mounting region and a connecting edge surrounding the mounting region. The peripheral edge of the bristle support and the sacrificial structures as well as the connecting edge of the cover part are then plasticised by heating. Then the bristle support and the cover part are pressed against one another, and the plasticised peripheral edge of the bristle support is welded to the plasticised connecting edge of the cover part. The plasticised material of the sacrificial structures flows into the volume remaining between the bristle support and the cover part and surrounded by the connecting edge, said plasticised material at least substantially filling said volume.