Conical Spring Fastener Assembly for Stable Wood Connections
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Solution Overview
Problem
Existing connecting means for wooden structures face issues with binding stability, misalignment, increased costs due to part replacement, and inefficiencies in applying pressing force, particularly with cone-shaped springs and cylindrical components.
Innovation Solution
A connecting means featuring a cylindrical pin with an angular screw head, a conical tip, a left-hand wound conical spring, and a disc-shaped abutment element with an inverted plate, along with a flat washer, which enhances axial positioning, pressing force, and reduces frictional forces during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a cone-shaped spring with right-hand thread is used, then the spring provides compression force, but the spring coils offset each other during coiling and when overloaded, causing radial bulging and potential spring failure
Solution Approach 1:
The patent inverts the standard right-hand thread configuration by using a left-hand thread for the conical spring. This reversal prevents the spring coils from offsetting radially during compression and loading, eliminating the radial bulging problem that leads to spring failure. The left-hand thread ensures that coils nest properly without protruding beyond previous coil limits.
2Manufacturing precision
If an annular upstanding flange is used on the stop element, then the spring is positioned, but the flange impedes full opening of the lower spring coil and requires more precise dimensional accuracy
Solution Approach 1:
The patent removes the problematic annular upstanding flange from the stop element design. Instead, it uses a simple disc-shaped stop element with a central hole that allows the conical spring to fully open and compress without obstruction. This extraction of the flange feature eliminates the dimensional accuracy constraints and assembly difficulties while maintaining proper spring positioning through the conical geometry itself.
3Force
If a cylindrical spring is used, then the spring provides compression force, but the spring may angle away from the common axis, leading to loss of binding stability
Solution Approach 1:
The patent replaces the cylindrical spring with a conical spring that has a varying diameter along its length. The conical geometry with smaller diameter at one end and larger diameter at the other provides inherent alignment and centering during compression, preventing the spring from angling away from the common axis. This curvature variation ensures the spring remains coaxial and maintains binding stability.
4Device complexity
If the lower cylindrical part of the pin has the same diameter as the upper part, then the structure is simple, but the spring cannot be properly centered and positioned axially
Solution Approach 1:
The patent introduces asymmetry into the pin design by making the lower cylindrical part have a different diameter than the upper cylindrical part. This diameter variation creates a tapered or conical transition zone that provides mechanical guidance and centering for the conical spring, ensuring proper axial positioning without requiring additional complex positioning features or high manufacturing precision.
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 design improves the accuracy of spring positioning, increases pressing force, reduces misalignment and friction, and simplifies assembly by centering the spring coils and aligning loads, thereby enhancing connection quality and reducing assembly time and costs.
Implementation Method 1
a cone-shaped spring which is threaded onto the pin and abuts the head with its smallest coil and a disc-shaped abutment element against which the spring abuts with its largest coil
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to a fastener for building structures, comprising a cylindrical pin (1) with an angular screw head (2) located on its upper part (3) for a suitable wrench and a conical tip (5) on its lower part (4), a thread (6) and a threaded conical spring (9) which abuts the screw head (2) with its smallest coil (8), and a disc-shaped stop element (11) against which the spring (9) abuts with its largest coil (10), wherein the stop element (11) comprises an inner hole (13) for receiving the pin (1) and has the shape of a plate turned upside down with the bottom (12) facing the screw head (2).