Helical Thread Insert Curved End for Removal

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Solution Overview

Problem

Existing helical coil thread inserts often damage the internal threads of soft materials during removal due to chamfered corners, leading to excessive replacement costs for complex parts like castings.

Innovation Solution

A helical-shaped thread insert with continuously curved surfaces at the coil ends and notches for tang removal, maintaining a constant diameter and smooth surface contact to reduce frictional damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If chamfered corners are used at the back end of the coil, then coil retention strength is improved, but thread damage during removal increases

Engineering Contradiction:

Improvecoil retention strengthVSAvoidthread damage during removal

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the chamfered corners with a continuously curved surface at the distal end of the coil. This curved surface eliminates sharp corners that cause stress concentration and thread damage during removal, while maintaining adequate retention strength through the overall coil geometry and engagement with the tapped aperture.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Strength

If sheared ends with chamfers are used, then resistance to removal is improved, but frictional damage to receiving material threads increases

Engineering Contradiction:

Improveresistance to removalVSAvoidfrictional damage to threads

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The continuously curved surface replaces the chamfered geometry at the coil ends. This curved surface reduces friction and contact stress during removal operations, preventing galling and damage to the softer receiving material threads while maintaining adequate retention through the helical engagement geometry.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Manufacturing precision

If constant diameter coil body is used, then manufacturing precision is improved, but removal difficulty increases due to increased friction

Engineering Contradiction:

Improveconstant diameter alignmentVSAvoidremoval ease

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The continuously curved surface at the distal end reduces the contact area and friction during removal operations. This localized curvature modification allows the constant diameter body to maintain manufacturing precision and engagement stability while reducing removal friction through the smoothed transition surface.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS7862283B2Tanged screw thread insert with improved removability

Publication Date: 2011.01.04 NEWFREY LLC

AI summary

A helical-shaped insert to engage a threaded fastener to a receiving member includes a helical coil having a plurality of coil sections having inner and outer surfaces forming a thread shape, and opposing first and second coil end sections. A removable tang extends radially inward from the first coil end section. A continuously curved surface at a finished end of the second coil end section forms a tangent point where the continuously curved surface tangentially meets the second coil end section outer surface. A notch in the first coil end section proximate to the tang and positioned between the inner and outer surfaces permits removal of the tang by mechanical failure at the notch. A second notch in the second coil end section and the continuously curved surface assist coil removal.