Thread-Cutting Concrete Screw with Angled Longitudinal Grooves

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Solution Overview

Problem

Thread-cutting screws require high screwing torque when inserted into concrete, and existing manufacturing methods are costly.

Innovation Solution

A thread-cutting screw design featuring four longitudinal grooves on the screw shank, with groove sides angled between 1° and 20° relative to the screw axis, allowing rock flour to be conveyed away from the screw end, reducing friction and torque requirements during insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional thread-cutting screws are used, then the thread can cut into the building material, but high screwing torque is required due to rock flour accumulation

Engineering Contradiction:

Improvescrewing torqueVSAvoidrock flour accumulation

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the harmful rock flour from the interface between the screw and building material by introducing longitudinal grooves that convey the flour away from the screwing area, thereby reducing friction and screwing torque

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The longitudinal grooves act as intermediary channels that facilitate the removal of rock flour, mediating between the thread-cutting action and the building material to prevent harmful accumulation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If traditional manufacturing methods are used, then the screw can be produced, but the manufacturing cost is high

Engineering Contradiction:

Improvemanufacturing costVSAvoidgroove structure

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent changes the geometric parameters of the screw by introducing longitudinal grooves with specific angles (1° to 20°) relative to the screw axis, optimizing the balance between rock flour removal efficiency and manufacturing simplicity

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

Significantly reduces the screwing torque needed to insert the screw into concrete by managing rock dust accumulation, making the screw easier to manufacture and use.

Implementation Method 1

the friction between the screw and the wall of the drilled hole can be reduced

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

rock flour is conveyed in the longitudinal grooves from the area at the end of the screw to a rear area in the longitudinal grooves in the direction of the screw head

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentEP2386770B1Thread cutting concrete screw

Publication Date: 2015.09.23 HILTI AG

Figure 1
Figure 2~3b
Figure 4

AI summary

The screw (1) i.e. concrete screw (2), has a thread (6) formed on a part of a screw shank (5), and a longitudinal groove (9) formed on a front section (7) of the screw, starting at an end (4) of the screw on the screw shank. The longitudinal groove is delimited on the screw shank by two longitudinal sides (10) running radially relative to a longitudinal axis (8) of the screw. The longitudinal sides are oriented at an angle between 1 and 20 degrees relative to a straight line running parallel to the longitudinal axis. The longitudinal groove is helically configured on the screw shank. The screw is partially made of metal such as steel, or fiber-reinforced plastic or fiberglass. An independent claim is also included for a method for producing a thread-tapping screw.