Dowel with Flat Contact Surface for Lightweight Panel Anchoring

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Solution Overview

Problem

Existing methods for securing fastening elements like screws and nails in lightweight panels are unreliable against high pull-out forces due to the low-density core and dense cover panels, which makes it difficult to achieve stable anchoring.

Innovation Solution

A dowel with a head and shank, featuring a flat contact surface at the end opposite the head, is designed to be anchored between the upper and lower cover plates, providing secure attachment by resting on the inside of the lower cover plate or a blind hole, and utilizing a multiple or double thread for enhanced grip, along with an extension that can engage with the lower cover plate for additional anchoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional fastening element is used in a lightweight panel, then installation is simple, but the anchoring reliability against pull-out forces is insufficient

Engineering Contradiction:
Improveanchoring reliabilityVSAvoiddowel structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The dowel is segmented into distinct functional zones: a head portion for driving and load distribution, a threaded shank for anchoring in the upper cover plate, and a flat contact surface at the end for bearing against the lower cover plate. This segmentation allows each portion to perform its specific function optimally, achieving reliable anchoring through distributed load paths rather than relying on a single anchoring mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The dowel features local quality variations with different thread configurations (multiple or double threads) in specific sections of the shank, and a specifically designed flat contact surface at the end. These localized features concentrate anchoring strength where needed while maintaining simplicity in other areas, resolving the contradiction between reliability and overall complexity.

Inventive Principle:
Principle #3Local quality

2Reliability

If a dowel with multiple threads is used to enhance grip, then pull-out resistance improves, but the installation time increases

Engineering Contradiction:
Improvepull-out resistanceVSAvoidinstallation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The dowel is pre-configured with multiple or double threads during manufacturing, so that when installed, the enhanced grip is achieved immediately without requiring additional installation steps. The complex thread pattern is prepared in advance, allowing quick installation while maintaining high pull-out resistance.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If the dowel is anchored between both cover plates, then stability against tilting improves, but the aesthetic appearance deteriorates due to visible penetration

Engineering Contradiction:
Improvetilting resistanceVSAvoidaesthetic appearance
Core Design Contradiction:
Stability of the object's compositionVSShape

Solution Approach 1:

Instead of having the dowel penetrate through both cover plates from the outside (which would be aesthetically pleasing but provide poor tilting resistance), the design inverts the anchoring approach: the head anchors in the upper plate while the end with the flat contact surface bears against the inner surface of the lower plate. This inverted configuration achieves superior tilting resistance while maintaining aesthetic appearance, as the dowel remains substantially flush with the outer surface.

Inventive Principle:
Principle #13The other way round (Inversion)

4Productivity

If a single rotation installation method is used, then installation speed increases, but the anchoring depth and reliability may be insufficient

Engineering Contradiction:
Improveinstallation speedVSAvoidanchoring depth
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The dowel employs parameter changes in its thread configuration, using multiple or double threads with specific pitch and depth parameters that allow sufficient anchoring to be achieved within a single rotation. The thread geometry is optimized so that the cumulative engagement length provides adequate anchoring depth despite the limited number of rotations during installation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3214321B1Assembly with a lightweight structural panel and a dowel and method for installing a dowel in a lightweight structural panel
Publication Date: 2020.08.12 WURTH INT AG
  • EP3214321B1 patent drawingFigure 1~4
  • EP3214321B1 patent drawingFigure 5~7
  • EP3214321B1 patent drawingFigure 8~10

AI summary

The invention relates to a dowel (10) for lightweight panels, wherein a lightweight panel (42) has an upper cover plate (20) and a lower cover plate (38) made of compact, compression-resistant material and a core (44) arranged between the cover plates made of material with a lower density than the cover plates, in particular paper honeycomb or foam, wherein the dowel has a head (12) and a shaft (28), wherein the head has a drive element (18) accessible from a top side of the head and an outer side of the shaft has a thread (30), wherein a top side of the head defines a first plane, wherein a receiving channel (40) for a fastening element extends through the head and at least partially through the shaft, characterized in that an end of the shaft opposite the head has a flat contact surface (36) which is parallel to the first plane.