Sealing Screw with Support Thread and Elastomer Washer
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Solution Overview
Problem
Existing connections between building profiles and outer walls, such as sill or door frame parts, face challenges in maintaining a durable seal due to movements caused by traffic, vibrations, and temperature changes, leading to water penetration issues.
Innovation Solution
A screw design featuring a conical sealing washer with an elastomer layer and a support thread coated with a sealant that extends 360° around the support thread, ensuring a permanent seal by preventing the screw shank from moving relative to the profile, and maintaining thread engagement for radial and axial stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional screw with sealing washer is used to connect a profile to an outer wall, then the connection allows for some movement due to traffic loads and temperature changes, but water penetration occurs in the long term due to seal failure
Solution Approach 1:
The screw shank is segmented into three distinct functional zones: an unthreaded shank section for initial positioning and seal engagement, a support thread section for stable anchoring with movement accommodation, and an anchoring thread section for secure fastening. This segmentation allows each zone to perform its specific function optimally while maintaining overall sealing reliability.
Solution Approach 2:
The unthreaded shank section performs a preliminary positioning function before the threaded sections engage. By providing a non-threaded transition zone, the screw ensures proper alignment and initial seal contact before the support thread engages the profile, preventing premature seal failure due to misalignment or excessive stress.
2Adaptability or versatility
If the sealing washer is made elastic to accommodate movements, then the seal can follow profile movements, but the sealing pressure decreases over time due to drying out and relaxation
Solution Approach 1:
The sealing system uses a composite structure combining an elastic sealing washer (typically rubber or elastomer) with a rigid or semi-rigid profile and screw assembly. The elastic material provides movement following capability while the rigid support thread and profile structure maintain stable geometric relationships and prevent excessive relaxation, preserving sealing pressure over time.
Solution Approach 2:
Different parts of the connection have different mechanical properties optimized for their specific functions: the sealing washer is highly elastic for movement accommodation, the support thread has moderate elasticity for stress distribution, and the profile and screw head are rigid for structural stability. This local differentiation ensures both movement adaptability and sustained sealing force.
3Reliability
If the support thread is added below the screw head to prevent loosening, then the screw remains secure during profile movements, but the complexity of the screw design increases
Solution Approach 1:
The support thread and anchoring thread are merged into a single continuous screw shank, eliminating the need for separate fastening components. The transition from unthreaded to threaded sections is integrated smoothly along the shank, reducing part count while maintaining anti-loosening functionality through the support thread's engagement with the profile.
Solution Approach 2:
The screw assembly serves multiple functions through its different sections: the unthreaded shank provides positioning and seal engagement, the support thread provides anti-loosening and movement accommodation, and the anchoring thread provides secure fastening. This multi-functionality is achieved within a single component design, avoiding the need for multiple separate parts.
4Manufacturing precision
If the unthreaded shank section is made long to ensure proper seal positioning, then the seal can be accurately positioned, but the screw becomes difficult to install and the profile thickness requirement increases
Solution Approach 1:
The unthreaded shank section length is optimized to a specific range that balances seal positioning accuracy with installation ease. By controlling this parameter within defined limits, the design ensures sufficient length for proper seal engagement while maintaining compatibility with standard profile thicknesses and drill bit lengths, facilitating easier installation.
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 achieves a long-term, moisture-tight seal by ensuring the sealant fills the space between the support thread and the profile's internal thread, preventing water ingress and securing the screw against loosening, while allowing for easy assembly through push-through installation.
Implementation Method 1
The conical sealing washer, which is arranged under the screw head and consists of a metal back and an elastomer layer attached to its underside
Implementation Method 2
the support thread of the screw is coated with a sealant that extends axially continuously from at least one flank tip to the next flank tip, 360° around the circumference of the supporting thread
Data Source
Figure 1
Figure 2
AI summary
The connection has a screw (10) with a support thread (18) at a shaft (12), and a seal disk (40) with an elastomer layer attached at a lower side of a metallic back plate. The disk sealingly lies at a profile i.e. hollow profile (50), such that the thread is covered with a sealant (24) i.e. adhesive. The sealant is attached at a thread circumference at 360 degrees such that an area between the support thread and an inner thread of a borehole of the profile is filled and sealed. An axial length of a thread-free shaft section (20) is smaller than a length of the shaft received by the disk.