Joint forming devices
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Solution Overview
Problem
Conventional fastening elements for joint forming devices in the furniture industry, particularly in flat pack furniture, face limitations in pull-out resistance due to the friable nature of composite panel materials, as they often rely on plastic sleeves that lack sufficient strength and rigidity, leading to inadequate anchorage and ease of disassembly.
Innovation Solution
A fastening element featuring a metal sleeve with an expandable section comprising axially extending slits forming flexible fingers with outwardly facing cutting edges, which are designed to cut into the panel material upon axial displacement, providing a strong and rigid anchorage by penetrating deeply into the panel, and optionally incorporating barbs for additional stability, while allowing for helical extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plastic sleeve is used in the fastening element, then the device is easier to manufacture and assemble, but the pull-out resistance is insufficient due to lack of strength and rigidity
Solution Approach 1:
The fastening element combines a metal sleeve with high strength and rigidity properties with a plastics coating layer. This composite structure provides both the mechanical strength needed for pull-out resistance and the manufacturing advantages of plastic components. The metal sleeve forms the load-bearing structural core while the plastics coating provides corrosion protection and facilitates assembly.
Solution Approach 2:
The sleeve is designed with different material properties at different locations: the metal portion provides strength and rigidity where mechanical loading occurs, while the plastics coating provides protection and surface properties where environmental exposure occurs. This localized material differentiation optimizes both strength and manufacturability.
2Strength
If the sleeve is made from metal with cutting edges, then the anchorage strength is significantly improved, but the device complexity increases
Solution Approach 1:
The metal sleeve is divided into distinct functional sections: an expandable section with cutting edges for anchorage, a central body section, and a threaded section for the fastening mechanism. This segmentation allows each portion to be optimized for its specific function while maintaining overall structural integrity and relatively simple manufacturing.
3Strength
If the fastening element is designed for strong anchorage with cutting edges, then the joint strength is improved, but the ease of disassembly is reduced
Solution Approach 1:
The fastening element employs a dynamic expansion mechanism where the metal sleeve can be radially expanded using a cam or wedge mechanism. During installation, the sleeve is expanded to cut into the panel material for strong anchorage. During disassembly, the expansion force is reversed to contract the sleeve, allowing removal without damaging the panel.
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 solution significantly enhances pull-out resistance by ensuring the fastener cannot be easily removed without causing panel disintegration, offering greater joint strength and stability, and facilitates easy disassembly through angled cutting edges and a mechanism for retracting fingers.
Implementation Method 1
the expander operatively engaging the sleeve in use to cause outward movement of its expandable section upon axial displacement of the fastening element relative to the sleeve
Implementation Method 2
the expandable section of the sleeve being insertable into a face hole in a first one of the panels, with said cutting edge having sufficient strength to cut into the panel material in use of the device
Data Source
AI summary
A fastening element (20) is provided for use with a tightening element (14) in a device for forming a joint between two panels (18,22). The fastening element is elongate and has a head (13) at one end for engaging the tightening element, an expander (15) at the other end and a shank (11) extending there between. The fastening element further comprises a sleeve (10) having an expandable section (16) at one end extending over the expander, with the expander operatively engaging the sleeve to cause outward movement of its expandable section upon axial displacement of the fastening element relative to the sleeve. The sleeve is provided with at least one outwardly facing cutting edge (19) on its expandable section. The cutting edge has sufficient strength to cut into the panel material in use of the device, when the expandable section is inserted into a face hole in a first one of the panels.