Weld Stud Convex End Face Arc Migration

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Solution Overview

Problem

Conventional welding studs for drawn arc welding often result in uneven melting and poor joint quality due to the arc migrating to specific points, leading to weakened joints and process sensitivity.

Innovation Solution

A welding stud with an outwardly curved end face, preferably rotationally symmetrical and shaped as a spherical segment, ellipsoidal segment, or paraboloidal segment, which merges smoothly into the side face, reducing arc migration and ensuring uniform melting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional welding stud with a flat end face is used, then the welding process is simple, but the arc migrates to specific points causing uneven melting and poor joint quality

Engineering Contradiction:
Improveuniformity of meltingVSAvoidshape of end face
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies the spheroidality principle by replacing the conventional flat end face with a convex curved end face. This curvature prevents the arc from concentrating at specific points or edges, thereby eliminating uneven melting and improving weld joint quality. The convex shape distributes the arc energy uniformly across the end face surface, directly resolving the technical contradiction between manufacturing precision and device complexity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If the end face is made convex to prevent arc migration, then uniform melting is achieved, but the manufacturing complexity increases

Engineering Contradiction:
Improvejoint qualityVSAvoidmanufacturing of end face
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The convex curved end face design implements the spheroidality principle to improve reliability by preventing arc migration and ensuring uniform melting. While this increases manufacturing complexity compared to a flat surface, the patent demonstrates that the curved geometry can be achieved through standard manufacturing processes, making the trade-off acceptable for the significant improvement in weld joint quality and process reliability.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Productivity

If excessive welding energy is applied, then the welding process is faster, but material vaporization occurs at the edge compromising joint strength

Engineering Contradiction:
Improvewelding speedVSAvoidjoint strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The convex curved end face prevents excessive welding energy from concentrating at the edges, thereby preventing material vaporization while maintaining welding speed. The curvature distributes the arc energy uniformly across the end face, allowing for efficient welding without compromising joint strength through edge vaporization.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent applies parameter changes by modifying the geometric parameters of the end face from flat to convex curved. This geometric parameter change fundamentally alters how welding energy is distributed, preventing the harmful concentration of energy at edges that leads to vaporization, while still maintaining productive welding speeds.

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

This design achieves consistent and improved joint quality by preventing arc concentration, enhancing the strength and reliability of the welds, making them less sensitive to process disturbances.

Implementation Method 1

an electric arc is ignited between the stud's end face and the component

Methodology Applied
Scientific EffectElectric arc: Electric Arc

Implementation Method 2

Both parts are melted and joined together

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

the arc does not migrate to a specific point, which significantly improves the uniformity of the melting process

Methodology Applied
Scientific EffectArc distribution: Electric Arc

Data Source

PatentEP3174664B1Weld stud for drawn-arc stud welding
Publication Date: 2020.07.08 BAYERISCHE MOTOREN WERKE AG
  • EP3174664B1 patent drawingFigure 1
  • EP3174664B1 patent drawingFigure 2

AI summary

A weld stud for drawn-arc stud welding has a functional portion and a welding portion which represents one end of the weld stud and which is delimited by a front face that is curved outwards in a longitudinal direction of the weld stud.