One-Piece Toothbrush Handle With Offset Recesses

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Solution Overview

Problem

Existing methods for manufacturing toothbrush handles are inefficient, requiring additional assembly steps for two-piece hollow handles, increasing manufacturing costs and cycle time, and group packaging is cumbersome with forceful perforation requirements.

Innovation Solution

A one-piece handle with offset recesses forming a cavity, produced via injection molding with an injection molding tool featuring finger elements that prevent plastic flow, eliminating the need for assembly and reducing material usage, thereby reducing production costs and cycle time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a two-piece hollow handle is used, then the handle achieves a voluminous shape with low weight, but an additional assembly operation is required increasing manufacturing cycle time and costs

Engineering Contradiction:
Improvehandle weightVSAvoidmanufacturing cycle time
Core Design Contradiction:
Weight of moving objectVSProductivity

Solution Approach 1:

The patent merges two separate handle parts into a single integrated hollow handle body that is injection-molded as one piece. The hollow cavity is formed directly during the injection molding process using a specific mold design, eliminating the need for separate assembly operations while maintaining the lightweight and voluminous characteristics of hollow handles.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If a solid handle is used, then the handle structure is simple and can be produced in one piece, but material consumption increases leading to higher costs and longer cooling times

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidmaterial consumption
Core Design Contradiction:
Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent segments the handle structure by introducing a hollow cavity within the handle body. This segmentation reduces material consumption and manufacturing costs while maintaining structural integrity. The hollow cavity is formed through offset recesses that pass through the wall and open into the cavity, creating a lightweight yet strong handle structure.

Inventive Principle:
Principle #1Segmentation

3Quantity of substance

If wall thickness is reduced to save material, then material costs decrease, but sink marks and inclusions risk increases

Engineering Contradiction:
Improvematerial usageVSAvoidsurface finish quality
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent implements preliminary action by designing offset recesses that are strategically positioned to provide structural support in critical areas during the injection molding process. These recesses are offset from one another and pass through the wall to open into the cavity, creating a framework that prevents sink marks and inclusions while allowing for reduced overall wall thickness and material consumption.

Inventive Principle:
Principle #10Preliminary action

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 results in a lightweight, voluminous, and ergonomically advantageous handle with reduced material costs and improved surface finish, minimizing sink marks and heat shrinkage, while maintaining consistent product quality.

Implementation Method 1

an injection molding tool with finger elements is used in the injection molding process for plastic

Methodology Applied
Scientific EffectInjection molding:

Implementation Method 2

In the closed state of the injection molding tool, the finger elements touch and prevent the flow of plastic at these contact points. In this way, recesses are formed in the solidified plastic material

Methodology Applied
Scientific EffectPhase change (molten to solid): Phase Change

Data Source

PatentEP1924167B1Handle for a brush, in particular a toothbrush
Publication Date: 2017.11.08 TRISA HLDG AG
  • EP1924167B1 patent drawingFigure 1~6
  • EP1924167B1 patent drawingFigure 7~13
  • EP1924167B1 patent drawingFigure 14a~21

AI summary

The inventive handle (12, 212) for a brush, in particular for a toothbrush (10) or a domestic brush (210), has an integral handle body (13, 213) with a hollow space (42, 242) which is surrounded by a wall (32, 232). Recesses (30, 230) which are offset in relation to one another and open into the hollow space (42, 242) are formed in the wall (32, 232). The handle (12, 212) is produced from a plastic in an injection-moulding process using an injection-moulding die which has finger elements, with sections of these finger elements touching in a sealing manner when the injection-moulding die is in the closed state and, as a result, these finger elements forming the recesses (30, 230) and the hollow space (42, 242) in the hardened handle (12, 212).