Thread Insert Drive Element for Brittle Sleeve Torque Transfer

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Solution Overview

Problem

Existing threaded inserts, particularly those made of coiled steel with high carbon content, face challenges in transferring screwing torque due to brittleness, and wound threaded inserts struggle with torque transmission in the axial direction, limiting their applicability in thread forming and connection stability.

Innovation Solution

A drive element with a receptacle and axial connecting section is designed to transmit torque to the threaded insert sleeve, featuring a drive profile and a connecting section that forms a positive or non-positive connection, allowing torque transfer primarily in the radial direction, suitable for hardened or brittle inserts, and enabling thread forming or cutting through the external thread.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a coiled profile strip is used to form a threaded insert sleeve, then material usage is reduced and manufacturing cost is lowered, but torque transmission capability deteriorates due to brittleness when hardened

Engineering Contradiction:
Improvemanufacturing costVSAvoidtorque transmission capability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The threaded insert is divided into two functional parts: a coiled profile strip forming the external thread and internal thread, and a separate drive element with drive profile inserted into a receptacle. This segmentation allows the coiled strip to be made from hardenable material for thread forming while the drive element provides the torque transmission path, resolving the contradiction between cost-effective coiled construction and reliable torque transmission.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drive element acts as an intermediary component that bridges the drive tool and the coiled profile strip. It transmits torque from the drive tool through the receptacle to the threaded insert sleeve, enabling reliable torque transmission without requiring the coiled strip itself to transmit torque axially, thus solving the brittleness problem while maintaining manufacturing advantages.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If high carbon content steel is used to achieve the required hardness for thread forming, then thread forming capability is improved, but brittleness increases making torque transmission difficult

Engineering Contradiction:
ImprovehardnessVSAvoidtorque transmission capability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The system separates the thread-forming function (requiring high hardness) from the torque-transmission function. The coiled profile strip is made of hardenable material for thread forming, while the drive element provides a separate torque transmission path, allowing the use of high-carbon steel without suffering from brittleness-related torque transmission failures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drive element is designed with specific geometric parameters (circular cross-section, centralized axis) that optimize its torsional strength and torque transmission capability, compensating for the brittleness of the hardened coiled strip by providing a dedicated torque transmission pathway with superior mechanical properties.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If torque is transmitted axially through the threaded insert sleeve, then thread forming is enabled, but the structure becomes unsuitable for hardened brittle materials

Engineering Contradiction:
Improvethread forming capabilityVSAvoidbrittleness resistance
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

Instead of transmitting torque axially through the threaded insert sleeve (traditional approach), the invention inverts the approach by using a drive element inserted into a receptacle at the rear end. Torque is transmitted from the drive tool through the drive element to the threaded insert sleeve, enabling thread forming in hardened brittle materials that cannot transmit torque axially.

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

Solution Approach 2:

The drive element serves as an intermediary that enables thread forming in brittle materials by providing a torque transmission path that does not rely on axial torque transmission through the brittle threaded insert sleeve itself, thus allowing thread forming capability while accommodating material brittleness.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If a drive helix is anchored via external profile, then torque transmission is improved in the leading area, but the structure becomes more complex

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The drive element combines multiple functions into a single component: it provides the drive profile for torque transmission, contains the receptacle for drive tool engagement, and features the connecting section for integral connection to the threaded insert sleeve. This multi-functionality achieves reliable torque transmission without the complexity of separate drive helix and anchoring mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The drive element merges the drive mechanism and connection mechanism into one integrated component. The receptacle, drive profile, and connecting section are combined in a single element that is inserted into the threaded insert sleeve, simplifying the overall structure compared to separate drive helix and anchoring systems while maintaining torque transmission reliability.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3219442B1Drive element for transmitting a torque to a thread insert sleeve
Publication Date: 2022.01.19 LUDWIG HETTICH
  • EP3219442B1 patent drawingFigure 1a~1e
  • EP3219442B1 patent drawingFigure 2a~3c
  • EP3219442B1 patent drawingFigure 4a~4d

AI summary

The present invention relates to a drive element (10) for transmitting torque to a threaded insert sleeve. The drive element (10) comprises a receptacle (12) with a drive profile (14), in which a drive tool for transmitting a torque from the drive tool to the drive element can be accommodated along a longitudinal axis (L) of the drive element, the longitudinal axis passing through the center of the Drive profile runs and corresponds to an axis of rotation of the drive element (10) about which the drive element rotates during torque transmission from the drive tool to the drive element. The drive element (10) also includes an axial connection section (16) with an outer surface (18) for forming a materially bonded, form-fitting and/or non-positive connection to the threaded insert sleeve, with the outer surface when a connection to a threaded insert sleeve, a torque can be transmitted from the drive element (10) to the threaded insert sleeve, the drive element (10) having at least in sections a cross-sectional area in which a circular line with a center through which the axis of rotation (L) runs is inscribed can.