Toothbrush Handle Recess Design for Simplified Injection Molding
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Solution Overview
Problem
The complexity of manufacturing toothbrushes with multiple materials and angled features leads to increased production costs and complexity, as it requires additional molding steps and the use of complex mold components, which complicates the molding operation and increases costs.
Innovation Solution
A toothbrush design that incorporates a base with a recess featuring complex angled boundaries, allowing for vertical mold removal and simplified manufacturing, using a combination of materials where a softer material is disposed in a recess surrounded by a harder material, with specific width configurations to avoid undercuts and facilitate easy mold parting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If multiple materials are used in the toothbrush handle, then aesthetic appeal is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple materials (thermoplastic elastomer and thermoplastic polymer) into a single integrated handle structure through one injection molding process. The softer TPE material forms a grip portion while the harder TPP material forms the body, both molded simultaneously in a single operation, eliminating the need for separate molding steps and assembly operations.
Solution Approach 2:
The patent utilizes composite material construction by injecting a first material (thermoplastic elastomer) and a second material (thermoplastic polymer) into the same mold cavity in sequence. The softer first material is injected first to form the grip portion, then the harder second material is injected to form the body, creating a multi-material composite structure with differentiated properties.
2Shape
If angled edges are formed on the toothbrush, then aesthetic appeal is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates asymmetric angled edges on the handle, specifically forming edges at angles between 30-60 degrees relative to the longitudinal axis. These asymmetric geometric features are achieved through the mold design, creating visually appealing angular transitions between the grip portion and body without requiring additional manufacturing steps.
Solution Approach 2:
The angled edges and complex geometric features are pre-formed during the injection molding process itself, rather than requiring subsequent machining or finishing operations. The mold cavity is designed with the final angular geometry already incorporated, allowing the thermoplastic materials to take the desired angular shapes as they are injected and cooled.
3Manufacturing precision
If complex mold components are used to achieve angled edges, then manufacturing precision is improved, but production cost increases
Solution Approach 1:
The patent divides the handle into distinct functional segments (grip portion and body) with a clear transition zone. The angled edges serve as geometric transitions between these segments, and the injection molding process naturally creates these transitions through material flow and cooling patterns, eliminating the need for complex adjustable mold components.
Solution Approach 2:
The patent controls the geometry of angled edges by adjusting molding parameters such as injection pressure, temperature, and cooling rates, rather than relying on complex mechanical mold components. By optimizing these process parameters, precise angular edges at 30-60 degree angles are achieved through the material's solidification behavior in the mold cavity.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An oral care implement is described herein. The oral care implement has a base having a handle region, an oral engaging region and a neck between the handle region and the oral engaging region. A recess surrounds the handle and/or the neck and has a first boundary and a second boundary, and the first boundary is further from a distal end than the second boundary. The first boundary has an angle of greater than about 90 degrees with respect to a mold parting line of the oral care implement. The base has a first material, and a collar made of a second material which is different than the first material, is disposed in the recess.