Contact Tip and Diffuser Preload Structure Against Loosening

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Solution Overview

Problem

The threaded connection between the contact tip and diffuser in MIG welding torches tends to loosen due to mechanical vibration and temperature cycling, leading to a loss of contact integrity.

Innovation Solution

A contact tip and diffuser assembly design featuring a non-threaded section that elongates along the longitudinal axis as the threaded sections mate, providing a preload to enhance the connection and maintain electrical contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a threaded connection is used to attach the contact tip and diffuser, then the assembly is easy to manufacture and disassemble, but the connection loosens due to mechanical vibration and temperature cycling

Engineering Contradiction:
Improveease of assemblyVSAvoidconnection stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The non-threaded section of the contact tip is designed to elongate along the longitudinal axis as the threaded section is screwed into the diffuser, creating a preload force before the threaded connection is fully tightened. This preliminary elongation action ensures that the contact surfaces are pressed together with sufficient force to maintain electrical contact and resist loosening during subsequent vibration and temperature cycling.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the contact tip and diffuser are rigidly connected, then electrical contact is maintained, but the assembly cannot accommodate thermal expansion and contraction

Engineering Contradiction:
Improveelectrical contact integrityVSAvoidthermal cycle accommodation
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The non-threaded section of the contact tip is designed with elastic properties that allow it to change its dimensional parameters (elongate and compress) in response to thermal expansion and contraction. This parameter change capability enables the assembly to accommodate temperature variations while maintaining continuous electrical contact between the contact tip and diffuser through the elastic deformation of the non-threaded section.

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

The assembly ensures reliable and stable electrical conduction through the contact tip and diffuser, preventing loosening and maintaining consistent welding performance.

Implementation Method 1

The non-threaded section is configured to elongate along the longitudinal axis as the threaded section is screwed into the mating threaded section past a point where the contact surfaces have established contact

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2563542B1Contact tip and diffuser
Publication Date: 2025.08.13 LINCOLN GLOBAL INC
  • EP2563542B1 patent drawingFigure 1A~1B

AI summary

A contact tip (105) includes a first threaded section (135) and a first non-threaded section (140). The length of the first non-threaded section (140) is at least a fifth of the length of the first threaded section (135) along a longitudinal axis (125). The contact tip (105) further includes a first contact surface (145). A diffuser (110) includes a second non-threaded section (175) and a second threaded section (170) configured to mate with the first threaded section (135) of the contact tip (105). The diffuser further includes a second contact surface. The first non-threaded section is configured to elongate along the longitudinal axis as the first threaded section is screwed into the second threaded section past a point where the first contact surface and the second contact surface have established contact.