Ground Screw With Concave Thread Flank for No Pre-Drilling

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing ground screw devices require complex assembly processes, are limited to anchoring rod-shaped objects, and have low tensile force capacity due to small thread engagement volume and need pre-drilling, restricting their application.

Innovation Solution

A ground screw with a concave thread flank facing the screw head and a shark-fin shaped thread profile that cuts into the ground during installation, expanding the screw core diameter and compacting soil for enhanced anchoring, allowing high tensile forces without pre-drilling, and featuring a receptacle for various objects with a fastening screw.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a ground screw with increasing core diameter is used to compact soil radially outward, then anchoring strength is improved, but pre-drilling is required which increases assembly complexity

Engineering Contradiction:
Improveanchoring strengthVSAvoidassembly complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

Instead of the conventional approach where the thread profile pushes soil outward requiring pre-drilling, this invention inverts the mechanism by designing a concave thread flank that pulls soil inward toward the screw core. The outer edge of the concave thread flank projects beyond the valley floor, creating a groove that draws soil into the thread chambers during screwing, eliminating the need for pre-drilling while maintaining anchoring strength.

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

2Ease of manufacture

If the thread profile has small engagement volume, then the screwing process is simpler, but tensile force absorption is reduced

Engineering Contradiction:
Improvethread profile simplicityVSAvoidtensile force absorption
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The invention changes the geometric parameters of the thread profile by introducing a concave thread flank where the outer edge projects beyond the valley floor. This creates a groove that increases the effective engagement volume with soil during screwing, allowing the thread to absorb higher tensile forces while maintaining a relatively simple overall thread structure that is easier to manufacture.

Inventive Principle:
Principle #35Parameter changes

3Strength

If the ground screw is driven deep into the ground to withstand tensile force, then load-bearing capacity is improved, but installation complexity increases

Engineering Contradiction:
Improveload-bearing capacityVSAvoidinstallation complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The concave thread flank design enables the ground screw to self-compact the surrounding soil during the screwing process itself, without requiring separate pre-drilling or compaction steps. The groove formed by the concave flank draws soil into the thread chambers and compacts it automatically as the screw is driven in, providing load-bearing capacity while simplifying installation to a single screwing operation.

Inventive Principle:
Principle #25Self-service

4Productivity

If energy-efficient screwing is achieved with the concave thread flank, then installation time is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvescrewing efficiencyVSAvoidthread profile manufacturing
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The concave thread flank with its specific geometry (outer edge projecting beyond the valley floor) optimizes the soil interaction during screwing, creating a self-compacting effect that reduces installation time and energy requirements. While the geometry is more complex than a standard thread, it can be manufactured using conventional machining or 3D printing processes, balancing manufacturing complexity with significant installation efficiency gains.

Inventive Principle:
Principle #35Parameter changes

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 efficient anchoring of diverse objects with high tensile strength using minimal screwing force, eliminating the need for pre-drilling and additional tools, and accommodating various soil types.

Implementation Method 1

the soil surrounding the ground screw is pushed from the edge of the thread profile towards the screw core, filling the chambers between the thread flanks with additional soil, thereby strengthening the anchoring. By expanding the screw core diameter, this additional soil is simultaneously compacted when the ground screw is screwed in

Methodology Applied
Scientific EffectSoil compaction: Compression

Implementation Method 2

Additional reinforcement of the anchorage is achieved by the screw head being wider than the screw core, which compacts the soil in the direction of screwing in when the ground screw is screwed in as far as the screw head will go

Methodology Applied
Scientific EffectSoil compaction: Compression

Data Source

PatentEP4413222B1Device for anchoring an object in the ground
Publication Date: 2025.09.17 CADILEK PATRICK
  • EP4413222B1 patent drawingFigure 1
  • EP4413222B1 patent drawingFigure 2
  • EP4413222B1 patent drawingFigure 3~5

AI summary

The invention relates to a device for anchoring an object (1) in the ground (2), the device comprising a ground screw (3) that has a receptacle (13) for the object (1) to be anchored, the screw-core diameter of which ground screw increases from the screw tip (4) to the screw head (5), wherein the ground screw (3) has a thread profile (6) having a thread flank (7a, 7b). Particularly stable anchoring results if the thread flank (7a) facing the screw head (5), viewed from the screw head (5) towards the screw tip (4), is concave, wherein the outer edge (10) of the concave thread flank (7a) projects beyond a trough base (11) towards the screw head (5).