Buffing Expanded Foam Skin Layer with Sodium Bicarbonate
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Solution Overview
Problem
The existing methods for processing foam items, such as those used in footwear, face challenges in efficiently removing the tough and dense skin layer formed during expansion, which hinders further molding and shaping into desired forms.
Innovation Solution
A system utilizing particulate sodium bicarbonate or other materials with specific hardness and size, applied at controlled pressures and angles, to buff and remove the skin layer from expanded foam items, followed by cleaning mechanisms to recycle and reuse the particles, facilitating the foam's transformation into its final shape and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the foam item is expanded to form a pre-form structure, then the foam item gains its basic shape and volume, but a tough and dense skin layer forms on the exterior that hinders further molding and shaping
Solution Approach 1:
The patent applies a preliminary action by forming the foam into a pre-form structure first, which establishes the basic shape and volume. This pre-forming step is intentionally performed before final molding to create a structure that can subsequently have its skin layer removed through buffing, enabling easier final shaping. The preliminary action sets up the conditions for subsequent processing steps.
Solution Approach 2:
The patent extracts the problematic skin layer from the foam item surface through buffing with abrasive particles. This removal action takes out the tough exterior layer that prevents effective molding, allowing the underlying softer foam material to be shaped more easily in subsequent molding operations.
2Ease of manufacture
If abrasive particles are used to remove the skin layer, then the skin layer is effectively removed to improve moldability, but the foam material may be degraded or damaged
Solution Approach 1:
The patent applies local quality by using abrasive particles with specific hardness properties that are softer than the foam material itself. This localized property selection ensures that abrasion occurs only on the harder skin layer while the softer foam substrate remains unaffected, achieving selective removal without damage to the underlying material.
Solution Approach 2:
The patent changes the physical parameters of the abrasive particles, specifically selecting particles with hardness between 1.0-5.0 Mohs and controlled size ranges (20-140 mesh). These parameter changes optimize the abrasive action to remove skin layer while preventing damage to the foam material, balancing effectiveness with material preservation.
3Manufacturing precision
If particles of specific hardness and size are applied at controlled pressure and angle, then precise control over skin layer removal is achieved, but the complexity of the buffing system increases
Solution Approach 1:
The patent employs pneumatic principles by propelling abrasive particles through a controlled stream using gas or air pressure. This pneumatic delivery system allows precise control over particle velocity, direction, and distribution without requiring complex mechanical buffing apparatus, thereby achieving manufacturing precision while relatively simplifying the overall system design.
4Loss of substance
If particles are reused after cleaning, then material waste is reduced and cost is lowered, but the cleaning and recycling process adds time and complexity
Solution Approach 1:
The patent implements particle recovery by collecting and cleaning used abrasive particles for reuse in subsequent buffing operations. This recovery process reduces the need for continuous particle replenishment, minimizing material loss and long-term costs, while the cleaning step prepares particles for effective reuse without significant time penalty.
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 method effectively removes the skin layer without degrading the foam, allowing for precise molding and shaping of foam items into their final forms, enhancing the processing efficiency and maintaining the integrity of the foam material.
Implementation Method 1
projecting particles at the foam item until at least a portion of the foam item is removed
Data Source
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AI summary
Foam items may be buffed using particles such as particulate sodium bicarbonate in accordance with the present invention. Foam items may be, for example, expanded EVA foam items pre-formed into an intermediate size and shape. A skin layer may be formed during the expansion of the foam item to form an expanded foam item which may be entirely or partially removed by buffing the item using particles projected with selected buffing parameters. The buffing parameters may be varied based upon the thickness of at least a portion of the skin layer and/or the desired degree of moldability for the foam item after buffing. Particulate sodium bicarbonate or other types of particles used for buffing may be recycled and reused for further buffing of foam items.