Cellulose Fiber Foam Molding With Density-Graded 3D Structure
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Solution Overview
Problem
Existing methods struggle to produce articles made of cellulose fibers with a defined three-dimensional shape, low weight, and varying thicknesses while maintaining high stiffness and cushioning properties.
Innovation Solution
A method involving high-shear mixing of cellulose pulp with water and air to create a foam blend, followed by molding and controlled drying to achieve an article with a low-density inner core and high-density outer skin, utilizing gas pressure differences and electromagnetic heating to control density gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional methods are used to produce cellulose fiber articles, then the article can be manufactured, but it cannot achieve both low weight and high stiffness simultaneously
Solution Approach 1:
The invention applies different density characteristics to different regions of the article: the inner core portion has low density (lightweight) while the outer skin portion has high density (stiff). This local quality differentiation allows the article to simultaneously achieve low overall weight and high stiffness where needed, resolving the contradiction between weight reduction and stiffness maintenance.
2Ease of manufacture
If uniform density is used throughout the article, then manufacturing is simplified, but the article cannot provide both cushioning and structural integrity
Solution Approach 1:
The invention creates different functional zones within the article: a low-density inner core for cushioning and shock absorption, and a high-density outer skin for structural integrity and scratch protection. This local quality variation enables the article to provide both cushioning and structural strength, overcoming the limitation of uniform density structures.
3Reliability
If thick portions are added to provide cushioning, then protection is improved, but the weight and manufacturing complexity increase
Solution Approach 1:
Instead of uniformly increasing thickness throughout the article, the invention concentrates the cushioning function in a low-density inner core portion. This allows thick cushioning protection to be achieved with minimal weight increase, as the low-density material provides cushioning effectiveness while adding less weight compared to high-density materials.
4Strength
If high density material is used throughout, then stiffness is improved, but the weight increases and softness is reduced
Solution Approach 1:
The invention applies high density only to the outer skin portion where stiffness is required for structural integrity and scratch resistance, while the inner core portion uses low density material. This localized high-density application provides necessary stiffness without the weight penalty of uniformly high-density construction, maintaining softness in the inner core while ensuring stiffness where needed.
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 produces articles with a low weight, high stiffness, and superior cushioning properties, allowing for varying thicknesses and reduced cycle times, while ensuring the article's integrity during transport.
Implementation Method 1
a high shear mixing action is applied to the cellulose pulp using a high-shear mixer. Such a high-shear mixer may, by way of example, comprise an outer fixed cylindrical stator and an inner rotatable rotor. The outer surface of the rotor is very close to the inner surface of the stator with only a very small radial gap between both surfaces, and the rotor is turning with a very high rotational speed. This leads to a high shear action exercised to the cellulose pulp between the inner surface of the stator and the outer surface of the rotor.
Implementation Method 2
the foam blend is inserted into a mold cavity. In a further subsequent step of the inventive method, the article is molded by heating the foam blend contained within the mold cavity.
Implementation Method 3
the article is molded by heating the foam blend contained within the mold cavity. Again, this method step may be similar to known molding methods. For example, heat may be applied to the foam blend by heating the mold surfaces of the mold, and/or by blowing a hot gas into the mold cavity. The object of the heating step is mainly to remove any remaining liquid water and humidity from the foam blend
Data Source
AI summary
A method of manufacturing an article at least partially made of cellulose fibers comprises inserting a cellulose pulp comprising cellulose fibers and water into a mixing cavity; applying a high shear mixing action to the cellulose pulp using a high-shear mixer, such that a foam blend comprising cellulose fibers, water and air bubbles is created; inserting the foam blend into a mold cavity; and molding the article by heating the foam blend contained within the mold cavity.