Solid Wood Building Panels With Differential Shrinkage Locking
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Solution Overview
Problem
Building panels with mechanical locking systems face issues such as gaps and system breakdown due to moisture content changes, leading to warping and tension loads, which are more pronounced in solid wood products compared to HDF boards and plywood.
Innovation Solution
The use of solid wood building panels with a mechanical locking system comprising a locking strip and groove, where the second element has a higher moisture shrinkage value than the first element, ensuring the locking strip shrinks more and pulls panels together to minimize gaps, and incorporating different wood species or annual ring orientations to achieve desired shrinkage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical locking system is used to join building panels, then the panels are securely locked together, but gaps arise between panels when moisture content decreases
Solution Approach 1:
The patent applies parameter changes by selecting wood species with different moisture shrinkage values for the first and second elements. The second element has a higher moisture shrinkage value (0.2-5%, preferably 0.5-2%, most preferably about 1% higher) than the first element, allowing it to shrink more during drying and thereby close gaps between panels while maintaining locking system stability.
Solution Approach 2:
The patent uses composite materials by combining two different wood species in the first and second elements. This composite structure allows exploitation of the different shrinkage characteristics of each wood species, with the second element's higher shrinkage compensating for gap formation and the first element providing dimensional stability.
2Ease of manufacture
If solid wood elements are used in building panels, then aesthetic appearance and natural properties are improved, but warping and shrinkage become more pronounced compared to HDF boards
Solution Approach 1:
The patent changes material parameters by carefully selecting wood species with specific shrinkage characteristics. The second element is chosen to have higher moisture shrinkage (0.2-5%, preferably 0.5-2%) to counteract warping, while the first element provides structural stability. This parameter optimization allows solid wood to be used while minimizing warping and shrinkage issues.
Solution Approach 2:
The patent creates a composite structure with two different wood species where each element compensates for the other's weaknesses. The first element provides dimensional stability while the second element's higher shrinkage特性 compensates for warping tendencies, achieving overall panel stability while maintaining solid wood aesthetics.
3Ease of operation
If the locking strip is made from the same wood species as the first element, then material consistency is maintained, but the locking system breaks down due to insufficient shrinkage compensation
Solution Approach 1:
The patent uses composite materials by making the locking strip from the second wood species (with higher shrinkage) rather than the first wood species. This allows the locking strip to shrink more during drying, maintaining tension and grip in the locking system, thereby preventing breakdown while still achieving material consistency within its own species.
Solution Approach 2:
The patent changes the material parameter of the locking strip by selecting a wood species with higher moisture shrinkage value. This parameter change ensures the locking strip shrinks adequately during drying to maintain locking system integrity and prevent breakdown, while the shrinkage value is controlled within the 0.2-5% range to avoid excessive distortion.
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 configuration effectively minimizes gaps and prevents mechanical locking system breakdown during climate changes, reducing warping and allowing for efficient production and multiple sanding of the installed floor surface.
Implementation Method 1
The second element has about the same or higher moisture shrinkage value than the first element, preferably in a range of about 0.2 to about 5 percent, more preferably in a range of about 0.5 to about 2 percent and most preferably about 1 percent higher
Data Source
AI summary
Building panels each comprise an upper first element of solid wood fixed to a lower second element of solid wood. The first and the lower second element are of different wood species. The building panels are provided with a mechanical locking system which comprises a locking strip at a first edge of a first building panel. The locking strip is provided with a locking element configured to cooperate with a locking groove at a second edge of a second building panel for horizontal locking of the first and the second building panels when a tension force is applied. The fiber direction of the first and the lower second elements is essentially along the first and the second edges. The lower second element has about the same or higher moisture shrinkage value than the first element. The locking strip comprises material of the lower second element.