Overmolded Gel Cushioning with Hard Shell for Injection Molding
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Solution Overview
Problem
Injection molded parts intended for contact with living bodies often cause chafing, pressure points, abrasions, or injuries due to material selection issues, as they cannot balance stability, strength, and flexibility, leading to cumbersome and costly separate production of cushioning components.
Innovation Solution
An injection molded part with a soft gel cushioning component completely covered by a harder, flexible, and elastically deformable hard component, which forms a peripheral flange-like edge and is integrated via overmolding during the injection molding process, allowing the cushioning part to withstand injection pressures and maintain dimensional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a soft cushioning material is used to prevent chafing and pressure points, then comfort and safety are improved, but the material cannot withstand injection molding pressures and loses dimensional stability
Solution Approach 1:
The cushioning component is divided into two distinct parts: a soft gel body providing cushioning and a hard gel shell providing structural stability. The soft gel body is completely enclosed by the hard gel shell, allowing each part to fulfill its specific function independently - the soft inner layer prevents chafing while the hard outer layer withstands injection molding pressures and maintains dimensional stability.
Solution Approach 2:
The invention uses a composite structure combining soft gel and hard gel materials. The soft gel body (cushioning material) is encased in a hard gel shell, creating a composite material system that simultaneously provides both cushioning comfort and structural stability. This composite approach allows the cushioning component to withstand injection molding pressures while maintaining its cushioning properties.
2Device complexity
If a soft cushioning component is integrated during injection molding, then production complexity is reduced, but the soft component cannot withstand the injection molding pressure
Solution Approach 1:
The soft gel body is pre-formed and placed into the mold cavity before the injection molding process begins. The hard gel shell is then formed around it during the injection process, creating a protective barrier before the high-pressure injection occurs. This preliminary arrangement ensures the soft component is protected from direct exposure to injection pressures while still being integrated into the final product.
Solution Approach 2:
The hard gel shell acts as an intermediary protective layer between the soft gel body and the injection molding pressure. This intermediate structure transfers and distributes the injection forces, protecting the soft cushioning material from direct pressure exposure while still allowing the integrated molding process to proceed.
3Stability of the object's composition
If a separate cushioning component is applied after molding, then the base part maintains dimensional stability, but the overall production cost and complexity increase
Solution Approach 1:
The invention merges the cushioning component formation with the base part injection molding process into a single integrated operation. The cushioning component (soft gel body enclosed in hard gel shell) is placed in the mold and overmolded with the base part material in one continuous process, eliminating the need for separate application steps and reducing overall production complexity while maintaining dimensional stability.
Solution Approach 2:
The soft gel body is nested within the hard gel shell, which is then nested within the base part structure during overmolding. This nested arrangement allows the cushioning component to be integrated into the base part as a unified structure, reducing production steps while maintaining the dimensional stability of the base part through the supportive hard gel shell.
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 enables a cost-effective and seamless integration of a cushioning molded part that can withstand injection molding pressures, providing effective cushioning without separate application, thus preventing damage and enhancing user comfort.
Implementation Method 1
The hard component is flexible and elastically deformable. The material of the hard component must be selected to withstand this elastic deformation and the injection pressure.
Implementation Method 2
The actual cushioning effect is achieved by a soft component formed by a soft, cast gel body.
Data Source
Figure 1a~2b
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AI summary
An injection-molded part formed from a base part (6) produced by injection molding and a cushioning molded part (1) attached to it can be produced by injection molding without additional joining steps by forming the cushioning molded part (1) with a soft, cast gel body forming a soft component (2), which is completely covered on its boundary surface with a harder, but flexible and elastically deformable material forming a hard component (3), which forms a circumferential flange-like edge (4) projecting laterally beyond the soft component (2), wherein the cushioning material (1) is connected to the base part (6) via the hard component (3) by overmolding the hard component (3) with the material of the base part (2) during the injection molding process for the base part.