Fixed Perforated Tube Foam Application for Composite Blistering
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Solution Overview
Problem
The production of composite elements with metallic outer layers and isocyanate-based foams often results in undesired air inclusions (vacuoles) between the metal sheet and the foam, leading to blistering and reduced adhesion, especially under temperature changes, and existing application methods like oscillating rake and multi-pronged applicators fail to produce uniform surfaces without vacuoles.
Innovation Solution
A process using a fixed tube with perforations, applied parallel and at right angles to the direction of movement, to apply the reaction mixture uniformly across the outer layer, minimizing vacuole formation and enhancing adhesion between the foam and the metal sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oscillating rake applicators are used to apply the reaction mixture, then the application speed can be increased, but air inclusions (vacuoles) are formed between the metal sheet and the foam
Solution Approach 1:
The applicator is divided into multiple stationary nozzles arranged in a line, each nozzle applying reaction mixture to a specific zone. This segmentation allows uniform distribution without the air entrapment problems of oscillating mechanisms while maintaining high application speed.
Solution Approach 2:
Instead of using an oscillating mechanism to distribute the material, the invention inverts the approach by using multiple stationary nozzles that simultaneously apply material across the width. This eliminates the oscillation-induced air inclusions while achieving the desired coverage.
2Productivity
If multi-pronged applicators are used to apply the reaction mixture quickly, then productivity increases, but large vacuole zones are produced on the outer layers
Solution Approach 1:
The application system is segmented into multiple stationary nozzles spaced along the width of the metal sheet. Each nozzle applies material to a narrow zone, and the zones coalesce to form a uniform foam layer without the large vacuole zones produced by multi-pronged applicators.
Solution Approach 2:
The reaction mixture is applied in a manner that allows it to self-level and coalesce uniformly across the surface. The stationary nozzles deliver material at controlled rates that enable the foam to rise uniformly without trapping air, eliminating the need for complex oscillating or multi-pronged mechanisms.
3Productivity
If the oscillation speed of the mixing head is increased to match twin belt speed, then continuous production is enabled, but the amount of reaction mixture applied becomes uneven across the width
Solution Approach 1:
Instead of relying on oscillation to distribute material across the width during continuous production, the invention segments the application into multiple stationary nozzles. Each nozzle maintains a constant position and application rate, ensuring uniform distribution across the entire width while enabling continuous production at high speeds.
Solution Approach 2:
The invention transitions from a dynamic oscillating applicator to a static array of nozzles. This dynamic-to-static transformation allows the system to operate continuously without the uneven distribution caused by oscillation, as each nozzle remains in a fixed position delivering material uniformly to its designated zone.
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
This approach significantly reduces vacuole formation and improves the uniformity and adhesion of the foam surface, even under adverse conditions, enhancing the quality of composite elements produced by continuously operating twin-belt systems.
Implementation Method 1
a) the liquid starting material for the isocyanate-based rigid foam is applied to the outer layer by means of at least one fixed tube which has openings and which has been placed, with respect to the outer layer, so as to be parallel and at right angles to the direction of movement
Data Source
AI summary
The invention relates to a process for the production of composites, composed of at least one outer layer b) and of an isocyanate-based rigid foam a), where the outer layer b) is moved continuously and the starting material for the isocyanate-based rigid foam a) is applied to the outer layer b), which comprises achieving the application of the liquid starting material for the isocyanate-based rigid foam a) by means of at least one fixed tube c) which has openings f) and which has been placed, with respect to the outer layer b), so as to be parallel to the plane of the outer layer and at right angles to the direction of movement.