Steel Cord Welding Electrodes With Flat Contact Areas for Stable Welds

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Solution Overview

Problem

The challenge in welding steel cord ends lies in achieving consistent electrical contact due to the fine, flexible, and irregularly twisted filaments, leading to varying contact resistance and less-than-desirable weld repeatability with existing welding apparatuses.

Innovation Solution

The design of welding electrodes with elongated flat areas oriented perpendicular to the cord direction, ensuring a consistent and efficient electrical and thermal contact, and the use of copper alloys for durability and conductivity, along with grooves to align the steel cord ends, addresses the issue of inconsistent contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional welding electrodes are used with steel cord ends, then welding can be performed, but the electrical contact is inconsistent leading to varying contact resistance and poor weld repeatability

Engineering Contradiction:
Improveweld repeatabilityVSAvoidelectrical contact consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The electrode surface is designed with specific local features including elongated flat areas and grooves that create predetermined contact zones. These local structural modifications ensure consistent electrical and thermal contact with the steel cord filaments, transforming the random contact pattern into a controlled and repeatable contact configuration.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The electrode geometry is pre-configured with grooves and flat areas that automatically align and organize the steel cord filaments before welding begins. This preliminary structuring of the contact interface ensures that the filaments are positioned optimally for consistent electrical contact, eliminating the need for manual alignment and improving weld repeatability.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If steel cord ends are clamped between electrodes, then welding can proceed, but the fine flexible filaments glide and rearrange causing varying contact resistance

Engineering Contradiction:
Improvewelding process efficiencyVSAvoidcontact resistance stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The electrode design incorporates features that accommodate the flexible nature of the steel cord filaments. The grooves and flat areas are shaped to guide and retain the flexible filaments in predetermined positions, preventing them from gliding and rearranging during the welding process, thus maintaining stable contact resistance.

Inventive Principle:
Principle #30Flexible shells and thin films

3Manufacturing precision

If standard electrode surfaces are used, then manufacturing is simple, but electrical and thermal contact with irregularly twisted filaments is insufficient

Engineering Contradiction:
Improveelectrical contact qualityVSAvoidelectrode fabrication complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The electrode surface is segmented into distinct functional zones including elongated flat areas and grooves. This segmentation creates multiple predetermined contact points that improve electrical and thermal contact with the irregularly twisted filaments. The segmented design is achieved through standard manufacturing processes, balancing improved contact quality with manufacturing feasibility.

Inventive Principle:
Principle #1Segmentation

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 configuration enhances the repeatability of welds by maintaining a stable electrical contact and heat distribution, reducing the risk of spark formation and improving the overall welding process for steel cord ends.

Implementation Method 1

an electrical current (AC or DC) is driven through the contact by the clamps. The steel will start to soften and melt

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The clamps can move to one another in a direction perpendicular the plane of the clamps. First the steel cord ends are made to contact and an electrical current (AC or DC) is driven through the contact by the clamps

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3787830B1Welding apparatus for butt welding steel cord using electrodes with one or more elongated flat areas and method of welding steel cord ends to one another using such apparatus
Publication Date: 2023.01.25 NV BEKAERT SA
  • EP3787830B1 patent drawingFigure 1~2b
  • EP3787830B1 patent drawingFigure 3a~3b
  • EP3787830B1 patent drawingFigure 4a~4b

AI summary

Steel cord is formed of many fine steel filaments that are twisted together. As these filaments are fine and hard they tend to glide over one another when pressed together. This makes the welding of steel cord ends particularly difficult as the filaments tend to reorganise when being clamped between the electrodes of a welding clamp. This results in a variable contact resistance that on its turn results in a variable weld quality. The inventor proposes an electrode (310, 310') configuration wherein the surface (314) of the electrode (310) comprises one or more elongated flat areas in one plane, and wherein the flat areas are perpendicularly oriented to the cord direction during welding. Also a welding apparatus is described having a pair of electrodes (310, 310') each having a surface (314, 314'), wherein the surface (314, 314') is such that when the first surface (314) is pressed against the second surface (314') in the absence of a steel cord end the first and second surface (314, 314') contact one another in two or more elongated flat areas (316(1), 316(2)), and wherein said flat areas (316(1), 316(2)) are perpendicularly oriented to the cord direction.