In-Mould Sports Helmet Bonding at Low Temperature
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Solution Overview
Problem
Cheaper materials like PVC, PET, and PETG used in sports helmets cannot withstand high temperatures during the forming process, leading to inadequate bonding between the outer and inner shells when formed at lower temperatures, resulting in helmets that lack integral structure and effective shock absorption.
Innovation Solution
Thermoforming of temperature-sensitive plastic materials like PVC, PET, or PETG into an outer shell, followed by integration with a pre-formed inner liner in a molding machine at lower pressure, lower temperature, and shorter time to create an integral fusion in-mould helmet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cheaper materials like PVC, PET, or PETG are used instead of polycarbonate, then manufacturing cost is reduced, but the material cannot withstand high temperatures during the forming process
Solution Approach 1:
The patent changes the temperature parameter of the forming process from high temperature (required for polycarbonate) to low temperature (suitable for PVC, PET, PETG). This allows the use of cheaper materials by adapting the process parameters to match the material's thermal characteristics.
Solution Approach 2:
The patent utilizes the phase transition properties of temperature-sensitive plastics at lower temperatures to achieve proper forming and bonding. The materials undergo appropriate phase changes during low-temperature forming to create the desired helmet structure.
2Temperature
If forming is done at lower temperatures to accommodate cheaper materials, then temperature resistance is maintained, but the outer shell and inner shell cannot bond together
Solution Approach 1:
The patent introduces a bonding agent or adhesive as an intermediary substance between the outer shell and inner shell. This mediator enables effective bonding at lower temperatures where the material itself cannot provide sufficient bonding capability, thus resolving the contradiction between low-temperature processing and bonding strength.
Solution Approach 2:
The patent creates a composite structure combining the outer shell material (PVC, PET, or PETG) with a bonding layer or treatment that enables adhesion. This composite approach allows the temperature-sensitive plastic to achieve both low-temperature processing compatibility and adequate bonding strength.
3Temperature
If normal forming processes are used at lower temperatures, then temperature resistance is maintained, but integral bonding between outer and inner shells is lost
Solution Approach 1:
The bonding agent serves as a mediator that enables integral bonding between the outer and inner shells at lower temperatures. Without this intermediary, the shells would remain separate; with it, they form a stable integrated structure suitable for low-temperature processing.
Solution Approach 2:
The patent modifies multiple process parameters simultaneously (temperature, pressure, time) to achieve integral bonding at lower temperatures. By adjusting these parameters together, the process maintains the temperature-sensitive plastic's integrity while still achieving proper bonding and structural stability.
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 method enables the formation of helmets with integral bonding between the outer and inner shells, providing equivalent collision protection and shock absorption to high-end polycarbonate helmets while reducing material costs.
Implementation Method 1
Outer shell material that cannot withstand high temperatures (e.g., 90°C or more), such PVC, PET, and PETG, is formed on thermo vacuuming machine.
Implementation Method 2
They are integrally formed into a sports helmet at lower pressure (0.5±0.1 bar), lower temperature (110±2 °C), and shorter time (168±5 sec).
Data Source
AI summary
A infusion in-mould helmet is disclosed. One side of a plastic sheet that is not resistant to high temperatures is attached with a protective tape that can withstand high temperatures, followed by printing, plastic removal, edge cutting, and hole drilling, to form an outer helmet. The outer helmet and a pre-formed inner helmet are disposed together in a molding machine to render an integrally formed sports helmet at lower pressure, lower temperature, and shorter time.