Solid Wood Panels With Differential Shrinkage Locking
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Solution Overview
Problem
Existing building panels with mechanical locking systems experience 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 building panels with upper and lower solid wood elements of different species, where the lower element has a higher moisture shrinkage value, and a locking strip made of the same material, configured to apply tension and minimize gaps by shrinking more than the upper element, thereby locking panels together effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical locking system is used to join building panels, then the panels can be 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 characteristics. The lower element is chosen to have higher moisture shrinkage than the upper element, allowing the lower element to shrink more during drying cycles and maintain contact pressure on the locking system, preventing gaps from forming between panels
Solution Approach 2:
The patent uses composite material construction by combining two different solid wood elements (upper and lower) with different species and shrinkage properties into a single panel structure. This composite approach allows the panel to leverage the differential shrinkage behavior of the two wood types to maintain locking system engagement and prevent gaps
2Reliability
If a mechanical locking system is used to join building panels, then the panels can be securely locked together, but the locking system breaks down due to tension load from moisture decrease
Solution Approach 1:
The patent changes the material parameter by selecting a lower wood element with higher moisture shrinkage capacity. This allows the lower element to actively shrink and maintain compressive force on the locking system during drying, counteracting the tensile loads that would otherwise cause locking system failure
Solution Approach 2:
The patent converts the harmful effect of wood shrinkage (which creates tension on the locking system) into a beneficial effect. By using a lower element with higher shrinkage, the natural shrinkage process generates compressive force that keeps the locking system engaged and prevents breakdown, turning the potential harm into a self-reinforcing mechanism
3Shape
If solid wood elements are used in building panels, then aesthetic and natural properties are improved, but warping occurs due to moisture content changes
Solution Approach 1:
The patent employs composite material construction with two different solid wood elements having different shrinkage characteristics. This differential shrinkage behavior between the upper and lower elements creates internal stress distribution that counteracts warping, allowing the panel to maintain dimensional stability while retaining the aesthetic qualities of solid wood
Solution Approach 2:
The patent changes the material composition parameter by combining two wood species with different physical properties. The lower element is specifically selected to have higher moisture shrinkage, which creates a balancing effect that prevents the panel from warping during moisture content fluctuations, while both elements remain solid wood to maintain aesthetic quality
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 minimizes gaps and prevents mechanical locking system breakdown by ensuring the panels remain securely locked during climate changes, reducing warping and allowing for efficient production methods.
Implementation Method 1
The second element has about the same or higher moisture shrinkage value than the first element... The locking strip comprises material of the second element... configured to apply tension and minimize gaps by shrinking more than the upper element
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3B
AI summary
Building panels each comprise an upper first element 31of solid wood fixed to a lower second element 32 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 6, at a first edge 5b of a first building panel 1.The locking strip provided with a locking element 8 configured to cooperate with a locking groove 14, at a second edge 5a of a second building panel 1a for horizontal locking of the first and the second building panels when a tension force is applied. The fibre direction FD of the first and the lower secondelements31, 32 is essentially along the first and the second edges 5b, 5a. The lower second element 32 has about the same or higher moisture shrinkage value than the first element. The locking strip comprises material of the lower second element (32).