Surmoulded Threaded Insert Fusible Zone Design

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Solution Overview

Problem

Conventional threaded inserts overmolded with a thread throughout their height face issues of accidental material engagement with the mold, leading to poor overmolding quality, and irreversible thread deterioration due to variable mold heights and insert lengths.

Innovation Solution

Incorporating a fusible zone of greater axial deformability between the threaded section and the heads, which deforms under axial compressive force without affecting the threaded section, allowing for adjustable insert length to match mold height and preventing thread damage during mold closure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the insert axial length is increased to match taller mold heights, then the insert can accommodate larger mold variations, but the internal thread becomes susceptible to irreversible deterioration during mold closure

Engineering Contradiction:

Improveadaptability to mold height variationsVSAvoidthread integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The insert is segmented into three distinct axial zones: a rigid threaded section for fastening function, a fusible zone for length adjustment, and heads for mold support. This segmentation allows the threaded section to remain protected while the fusible zone absorbs dimensional variations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fusible zone acts as an intermediary element between the threaded section and the heads. It absorbs compressive forces during mold closure and adjusts the insert length to match mold height, thereby protecting the threaded section from deterioration while accommodating mold variations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the mold closing force is applied directly to the threaded section, then the mold closure is achieved, but the internal thread suffers irreversible deterioration

Engineering Contradiction:

Improvemold closure efficiencyVSAvoidthread quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The fusible zone serves as a mediator that receives and absorbs the mold closing force applied to the heads. It deforms under compression to accommodate mold closure while shielding the threaded section from direct force application, thus maintaining thread quality without compromising closure efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The potentially harmful compressive force during mold closure is converted into a beneficial effect by designing the fusible zone to deform under this force. The force that would otherwise damage the thread is instead used to adjust the insert length and protect the threaded section.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the insert is made fully rigid to maintain thread integrity, then the thread is protected from deformation, but the insert cannot adapt to variable mold heights causing material engagement issues

Engineering Contradiction:

Improvethread integrityVSAvoidadaptability to mold height variations

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The insert is divided into rigid and flexible segments: the threaded section maintains rigidity for thread protection, while the fusible zone provides flexibility for length adjustment. This segmentation resolves the contradiction by localizing rigidity where needed and flexibility where adaptability is required.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different axial zones of the insert have different mechanical properties: the threaded section is rigid to protect thread integrity, while the fusible zone has controlled deformability to adapt to mold height variations. This local differentiation of material properties solves the contradiction between rigidity and adaptability.

Inventive Principle:

Principle #3Local quality

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

This solution mitigates material engagement issues and thread deterioration, ensuring consistent overmolding quality by allowing the insert to adjust its length to match the mold height, maintaining the integrity of the internal thread.

Implementation Method 1

the shaft comprises at least one fusible zone of greater axial deformability interposed between said threaded axial section and one of the heads, configured to deform under a predetermined axial compressive force applied to the heads without causing deformation of said threaded axial section

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP2316632B1A surmoulded threaded insert and process for making the same

Publication Date: 2013.06.05 BOLLHOFF OTALU SA

AI summary

The insert (10) has a leveled tube shaped body (11) with an axial deformability fusible zone that is interposed between a threaded axial section (T1) and one of two heads (12, 13) of the insert to be deformed under predetermined axial compression force applied to the heads, without causing deformation of the threaded axial section. The section is constituted by an annular groove (15) externally made in the insert in a plane perpendicular to its axis (X). The insert is realized by cold heading, boring or blindness. An independent claim is also included for a method for molding a thread insert.