Joining element and method of joining wood structures
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Solution Overview
Problem
Existing methods for joining wood structures, such as log construction and furniture assembly, face challenges including weak joints, laborious and expensive notching processes, and the need for specialized tools, which limit their effectiveness in forming strong and efficient connections, especially in construction settings.
Innovation Solution
A joining element and method that utilize a groove in the wood pieces to form both glue and pin joints, allowing for quick assembly of strong and stiff joints using a tapered joining element with plane and inclined surfaces, and a binding agent like polyurethane glue, which can be formed on-site without large machine tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal plates are used to join wood structures, then the joining process is simple, but the joint strength and appearance are poor
Solution Approach 1:
The joining element is divided into multiple functional parts: a body portion for insertion, a head portion for reinforcement, and multiple holes for pins. This segmentation allows each part to contribute to different aspects of joint performance - the body provides insertion capability, the head provides structural reinforcement, and the holes enable mechanical fastening with pins, collectively achieving both ease of manufacture and high joint strength
Solution Approach 2:
The joining element combines multiple materials and joining methods - wood or composite material for the element itself, metal pins for mechanical fastening, and adhesive for bonding. This composite approach integrates the advantages of each material and method, creating a joint that is both easy to manufacture and exceptionally strong
2Strength
If notching is used to join beam frame structures, then the joint strength is high, but the process is laborious and expensive requiring industrial equipment
Solution Approach 1:
The complex notching process is extracted and replaced by a simpler insertion process. Instead of cutting grooves and notches into the wood members using large industrial equipment, the joining element with its pre-formed body and head is simply inserted into pre-drilled holes, achieving comparable or superior joint strength with minimal equipment and labor
Solution Approach 2:
The complex shaping operations are performed in advance on the joining element itself during manufacturing, creating the body, head, and holes before installation. At the construction site, only simple hole drilling and insertion are needed, transferring the manufacturing complexity from the construction phase to the manufacturing phase where it can be more efficiently handled
3Manufacturing precision
If connecting blocks with grooves are used to join wood pieces, then the joint precision is high, but special tools are required for groove formation
Solution Approach 1:
Instead of cutting grooves into the wood members and fitting blocks into them, the approach is inverted: holes are drilled into the members and a joining element with a pre-formed body is inserted into the holes. This inversion eliminates the need for complex groove-cutting tools while maintaining high joint precision through the precise fit of the element in the holes
4Stability of the object's composition
If traditional joining methods are used, then material uniformity is maintained, but the joining time and labor cost are high
Solution Approach 1:
The joining element serves multiple functions simultaneously: it provides structural reinforcement through its head, enables mechanical fastening through its holes for pins, provides adhesive bonding surfaces on its body, and maintains material uniformity by being made of wood or composite materials. This multi-functionality allows all these benefits to be achieved in a single insertion operation, dramatically improving productivity while maintaining material uniformity
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
Enables the rapid and strong joining of large wood parts, providing immediate stability for continued installation work, with the ability to form joints at multiple support points and maintain uniformity in appearance and material properties.
Implementation Method 1
a binding agent like polyurethane glue
Data Source
Figure 1a~2
Figure 3a~4c
Figure 5a~5b
AI summary
A joining element (1) comprising at least two joint holes (2) for pin joints as well as a first plane surface (7a) and a second plane surface (7b) and an inclined surface (9a, 9b) slanting towards an outer edge (8) of the joining element and arranged at an angle with respect to at least one said plane surface (7a, 7b). A method comprises joining two wood structures (3a, 3b) to one another by using the joining element.