Toothbrush Head Overmolding for Mixed Bristle Tuft Integration

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Solution Overview

Problem

Existing toothbrush manufacturing methods lack flexibility in integrating different types of cleaning elements and bristle tufts, limiting design options to meet diverse consumer needs such as deep cleaning, sensitive cleaning, and gum massage.

Innovation Solution

A method involving the use of a hole perforation plate to arrange bristle tufts with varying properties, followed by energy application to form fuse balls at different distances from an energy source, and subsequent over-molding with plastic to create a cleaning element carrier, which is then integrated into a brush head.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If different types of cleaning elements and bristle tufts are integrated into one brush head, then design flexibility and cleaning performance are improved, but manufacturing complexity increases

Engineering Contradiction:
Improvedesign flexibilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The manufacturing process is divided into distinct stages: bristle tuft preparation, fuse ball formation, and overmolding. This segmentation allows each stage to be optimized independently, managing complexity while enabling diverse cleaning element integration.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The overmolding process serves multiple functions simultaneously: it forms the brush head structure, secures the bristle tufts through fuse ball embedding, and integrates different cleaning element types. This multi-functionality reduces the need for separate manufacturing steps.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If fuse balls are made larger than bristle tufts to anchor them securely, then bristle tuft retention is improved, but geometric precision of the brush head decreases

Engineering Contradiction:
Improvebristle tuft retentionVSAvoidgeometric precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The fuse balls are designed with non-uniform characteristics - larger in size for anchoring purposes but with controlled geometry in specific regions. This local quality variation allows secure retention while maintaining overall geometric precision through the overmolding process.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The fuse balls are formed with predetermined sizes and geometries before the overmolding step. This preliminary action ensures that the anchoring function is already optimized, and the subsequent overmolding simply integrates them without compromising geometric precision.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If multiple filament containers with different properties are used, then cleaning element diversity is improved, but process complexity increases

Engineering Contradiction:
Improvecleaning element diversityVSAvoidprocess complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Different filament containers provide filaments with specific properties (material, diameter, cross-section, shape, additives, coating) tailored for different cleaning functions. Each filament type is placed in specific locations within the brush head to optimize cleaning performance for different tooth surfaces and conditions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The method combines multiple filament types and cleaning element configurations into a single integrated brush head manufacturing process. By merging the selection, arrangement, and integration steps into one coordinated process, diversity is achieved without proportionally increasing complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables high design flexibility by securely integrating diverse cleaning elements and bristle tufts into a brush head, enhancing cleaning performance and user comfort.

Implementation Method 1

applying energy from the energy source to the ends of the one or more bristle tufts until fuse balls are formed

Methodology Applied
Scientific EffectThermal energy: Heating

Implementation Method 2

applying energy from the energy source to the ends of the one or more bristle tufts until fuse balls are formed

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

injecting molten plastic material into the brush head mold forming a toothbrush head

Methodology Applied
Scientific EffectInjection molding:

Data Source

PatentEP3753448B1Method for producing a toothbrush head
Publication Date: 2025.12.10 PROCTER & GAMBLE CO
  • EP3753448B1 patent drawingFigure 1A~1D
  • EP3753448B1 patent drawingFigure 2A~2E
  • EP3753448B1 patent drawingFigure 3a~3i

AI summary

A method for producing a (tooth)brush head or a part (10) thereof is provided comprising -providing at least two filament containers each comprising a supply of loose filaments (22) which differ in at least one property selected from filament material, filament diameter, filament cross-section, filament shape, presence or absence of additives and/or a coating, or a combination thereof; -picking one or more bristle tuft(s) (20) from the at least two filament containers and arranging them in a hole perforation plate (60) comprising one or more holes (70), which are shaped and distributed according to the desired bristle field (28) of the brush head to be produced; -arranging an energy source (80) so that the ends (23) of the bristle tufts (20) and the energy source (80) are arranged contactless, wherein the ends (23) of the bristle tufts (20) which shall be fused are arranged at different distances to the energy source (80), wherein the distance is adjusted according to the at least one property; -applying energy to the ends (23) of the bristle tufts (20) until fuse balls (24) are formed; -transferring the bristle tufts (20) to a molding position, wherein the distance of the fuse ball (24) of at least one bristle tuft (20a) is different to the distance of the fuse ball (24) of said bristle tuft (20a) in the fusing position; -over-molding of the fuse balls (24) of the bristle tufts (20) with molten plastic material thereby forming a cleaning element carrier (30); -transferring the cleaning element carrier (30) to a brush head mold and injecting molten plastic material into the brush head mold forming a toothbrush head (12, 16), wherein the cleaning element carrier (30) is over-molded thereby and the bristle tufts are still located in the hole perforation plate (60). Further a (tooth)brush head (12,16) or a part (10) thereof are disclosed that are produced by the method as disclosed herein.