Modular Welding Electrode for Bossed Nut and Stud Welding

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Solution Overview

Problem

Existing welding electrodes are limited in versatility, as they are typically designed for either bossed nut or stud welding, requiring separate devices for each process, and face issues with wear and maintenance due to mechanical and thermal stresses.

Innovation Solution

A modular welding electrode design featuring a replaceable lower electrode secured by a union nut, interchangeable piston rod attachments, and insulating components, allowing for both bossed nut and stud welding with enhanced durability and maintenance flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a welding electrode is designed for a specific welding process (bossed nut or stud welding), then the welding precision and reliability for that process is improved, but the versatility and adaptability of the device deteriorates

Engineering Contradiction:
Improvewelding reliabilityVSAvoidprocess versatility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The welding electrode is divided into modular components: a reusable housing and process-specific lower electrodes (projection nut electrode or stud electrode) that can be independently replaced. This segmentation allows the device to maintain reliable performance for each specific welding process while enabling versatility through component interchangeability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The housing is designed with universal features including threaded bores for different electrode types, a reusable pneumatic actuation system, and a standardized centering pin mechanism. This universality allows a single housing to support multiple welding processes (bossed nut welding and stud welding) through the interchangeability of lower electrodes.

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

2Reliability

If the lower electrode is made robust to withstand mechanical and thermal stresses, then the durability and reliability is improved, but the weight and complexity of the device increases

Engineering Contradiction:
Improveelectrode durabilityVSAvoidelectrode complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The electrode system is segmented into a robust reusable housing and replaceable lower electrodes. The housing contains all the complex pneumatic and mechanical components that need to withstand repeated stress, while the simpler lower electrodes can be replaced when worn. This segmentation concentrates the durability requirements on essential components only.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lower electrodes are designed as consumable components that can be easily replaced when worn or damaged. Rather than making the entire electrode assembly robust and expensive, only the critical housing and actuation mechanisms are designed for long-term durability, while the lower electrodes serve as replaceable, lower-cost components.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Productivity

If the centering pin is actively retracted into the housing using pneumatic actuation, then the productivity and automation level is improved, but the device complexity and energy consumption increases

Engineering Contradiction:
Improvewelding productivityVSAvoidactuation complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

A pneumatic actuation system is integrated into the housing to automatically retract the centering pin and lower electrode after welding. This pneumatic mechanism provides automated, high-speed retraction that improves productivity and consistency, eliminating the need for manual operation while maintaining relatively simple device architecture through the use of standard pneumatic components.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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

Enables versatile welding of both bossed nuts and studs using a single housing, with improved stability, reduced wear, and simplified maintenance through modular components and easy replacement of parts.

Implementation Method 1

The piston rod is pneumatically actuated. Such a welding electrode is known from DE 20 2012 006 321 U1. The pneumatic actuation of the piston rod allows the centering pin to be actively drawn into the housing.

Methodology Applied
Scientific EffectPneumatic actuation:

Implementation Method 2

This creates an electrical connection between the upper electrode, the bossed nut, the sheet metal, and the lower electrode. Due to the voltage drop between the bossed nut and the sheet metal, a significant amount of heat is generated, causing the bossed nut to weld to the sheet metal.

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

a union nut which engages in threaded engagement with the housing and secures the lower electrode against the housing

Methodology Applied
Scientific EffectThreaded engagement: Screw

Data Source

PatentEP3646981B1Welding electrode
Publication Date: 2026.03.25 DOCERAM
  • EP3646981B1 patent drawingFigure 1
  • EP3646981B1 patent drawingFigure 2
  • EP3646981B1 patent drawingFigure 3

AI summary

The invention relates to a welding electrode comprising a housing (1), a piston rod (2) arranged in the housing (1) and mounted to be axially displaceable, a lower electrode (16; 30) which is supported against the housing (1), and a union nut (17) which engages in threaded engagement with the housing (1) and secures the lower electrode (16; 30) against the housing. The welding electrode according to the invention is capable of welding both bossed nuts and bolts.