Wood Composite Material With Density-Stratified Layers
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Solution Overview
Problem
The increasing cost and decreasing quality of solid timber wood, coupled with the inefficiencies in wood-based composite materials like OSB, lead to issues with density variations and structural weaknesses, necessitating a wood composite material with superior performance, uniform appearance, and consistent physical properties.
Innovation Solution
A wood composite material is developed with surface layers denser than core layers, where the core contains at least 70 wt% less dense strands and the surface layers contain at least 70 wt% more dense strands, achieving a density range of 20-60 lbs/ft3, using a method that involves dividing wood strands by intermediate density and distributing them accordingly in the composite board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wood strands of differing densities are mixed in the panel, then the available supply of timber wood is used more efficiently, but density variations cause visual and structural problems
Solution Approach 1:
The patent divides the wood strands into different density categories (lighter and heavier strands) and segments them into separate layers within the panel structure. This segmentation allows efficient use of varying wood supplies while preventing harmful density clumping, as each layer maintains relatively uniform density characteristics.
Solution Approach 2:
The patent applies local quality by creating surface layers with different density characteristics than the core layer. The surface layers contain heavier strands for structural integrity and visual appearance, while the core layer contains lighter strands for cost efficiency and reduced weight, allowing each region to have optimized properties for its specific function.
2Weight of moving object
If lower density material is used in the panel, then the overall panel weight is reduced, but clumped material forms weak spots that compromise structural strength
Solution Approach 1:
The patent segments the panel into distinct layers with different density compositions. The core layer contains the lighter, lower-cost wood strands that reduce overall panel weight, while the surface layers contain heavier, stronger strands that prevent weak spot formation and maintain structural integrity. This segmentation prevents the harmful effect of clumped low-density material while achieving weight reduction.
Solution Approach 2:
The patent creates a composite material structure where layers of different density wood strands are combined. The core layer uses lighter strands to reduce weight, while surface layers use heavier strands to provide structural strength and prevent weak spots. This composite approach allows simultaneous achievement of weight reduction and strength maintenance.
3Strength
If higher density material is used in the panel, then structural strength is improved, but the panel becomes harder to sand and finish
Solution Approach 1:
The patent applies local quality by placing heavier, stronger wood strands specifically in the surface layers where they are needed for structural integrity and aesthetic appearance, while using lighter strands in the core layer. This localized placement ensures the surface is strong enough to be sanded and finished smoothly, while the overall panel maintains good structural strength.
4Strength
If conventional wood species are used, then the panel achieves sufficient strength, but the cost increases and faster-growing species are not utilized
Solution Approach 1:
The patent changes the parameter of wood species selection by incorporating faster-growing, lower-cost species (such as Paulownia, bamboo, or fast-growing pines) into the core layer while using slower-growing, higher-strength species in the surface layers. This parameter change allows the panel to achieve sufficient strength while utilizing faster-growing species to reduce harvest cycle time and cost.
Data Source
AI summary
Disclosed is a wood composite material comprising: wood strands disposed in surface layers and one or more core layers, whereby an intermediate density divides the wood strands so that the two surface layers of strands are more dense than the intermediate density, and the one or more core layers of the strands are less dense than the intermediate density, and wherein the core layer contains at least about 70 wt % of the strands that are less dense than the intermediate density; and the surface layers contain at least about 70 wt % of the strands that are more dense than the intermediate density.