Concrete Screw Thread Start That Prevents Helix Unwinding

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Solution Overview

Problem

Concrete screws with separate helix elements often experience unwinding during installation due to tapping forces, requiring strong connections that complicate and expense manufacturing.

Innovation Solution

A screw design featuring a monolithic thread start that leads the separate helix element during installation, shielding it from tapping forces and reducing the tendency to unwind, allowing for a robust and cost-effective manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a separate helix element is used for the screw thread, then the screw can be designed with modular components for potential manufacturing advantages, but the separate helix element tends to unwind from the shank during installation due to tapping forces

Engineering Contradiction:
Improvemodular manufacturingVSAvoidconnection stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The screw thread is divided into two separate sections: a monolithic thread start integrated with the shank and a separate helix element. This segmentation allows each part to be optimized independently - the thread start provides stable engagement while the separate helix element can be manufactured separately and attached later, combining manufacturing flexibility with structural stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The monolithic thread start is formed on the shank before the separate helix element is attached. This preliminary action creates a stable foundation that guides and supports the subsequent attachment of the helix element, preventing unwinding during the installation process by providing pre-formed engagement surfaces.

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If a strong connection is provided between the separate helix element and shank to prevent unwinding, then connection stability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveconnection stabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The connection problem is solved by segmenting the thread into two parts with different attachment methods. The thread start is monolithically formed with the shank requiring no additional connection, while the separate helix element uses a simpler attachment method to the already-stable thread start, reducing overall manufacturing complexity while maintaining connection stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The monolithic thread start acts as an intermediary element between the shank and the separate helix element. It provides a stable intermediate structure that simplifies the connection requirements for the helix element, as the thread start absorbs much of the mechanical stress and guidance requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the separate helix element is used, then material selection can be optimized for specific functions, but the tendency to unwind requires stronger and more expensive connection solutions

Engineering Contradiction:
Improvematerial selection flexibilityVSAvoidmanufacturing cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The thread is segmented into a monolithic thread start and a separate helix element, allowing different materials to be selected for each section based on specific functional requirements. The thread start can be made from materials optimized for engagement and guidance, while the helix element can use materials optimized for thread formation, reducing overall manufacturing cost despite material flexibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different material properties can be applied to different parts of the screw thread. The thread start can have material properties optimized for initial engagement and guidance, while the separate helix element can have material properties optimized for thread formation and strength, allowing local optimization without requiring expensive connection solutions.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4158209B1Screw with separate thread helix and integral thread start
Publication Date: 2024.05.22 HILTI AG
  • EP4158209B1 patent drawingFigure 1~3
  • EP4158209B1 patent drawingFigure 4

AI summary

The invention relates to a screw comprising a shank (10) having a tip end (11) and a rear end (18), which is located opposite the tip end, and at least one screw thread (30), which is arranged on the shank, which winds around the shank and which protrudes from the shank, wherein the screw thread comprises a separate screw thread section (38), which is constituted by a separate helix element (37) that is non- monolithically arranged on the shank. According to the invention, the at least one screw thread comprises a thread start (31), which extends further towards the tip end than does the separate screw thread section, and which forms a generally helical continuation of the separate screw thread section, wherein the thread start and the shank are monolithic.