Motor Vehicle Door Flange Joining via Laser Welding

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Solution Overview

Problem

Existing methods for joining metal sheets in motor vehicle bodywork components, such as hemming and butt welding, are costly, dimensionally unstable, and prone to geometric deviations, often requiring adhesives and sealants that complicate production and increase the risk of galvanic corrosion.

Innovation Solution

A method involving laser welding of two metal sheets with connection flanges that are folded back to create an open valley, where the second flange is welded parallel to the first, eliminating the need for adhesives and sealants, and ensuring dimensional stability by maintaining precise geometry through controlled overlap and angle adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If hemming joining with adhesive and sealant is used, then connection strength and sealing are improved, but production cost and process complexity increase

Engineering Contradiction:
Improveconnection strengthVSAvoidprocess complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the adhesive and sealant from the joining process, relying solely on mechanical hemming and welding operations to achieve both structural strength and sealing functionality. This removes the need for separate adhesive application and curing systems.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the sealing function into the mechanical hemming structure itself, where the folded flange and welded joint simultaneously provide both structural connection and moisture sealing, eliminating the need for separate sealant application.

Inventive Principle:
Principle #5Merging (Combining)

2Strength

If hemming joining with adhesive is used, then connection strength is improved, but production cost increases

Engineering Contradiction:
Improveconnection strengthVSAvoidproduction cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The invention extracts the adhesive from the process entirely, reducing material costs and eliminating equipment investment for adhesive application and curing systems, while maintaining connection strength through optimized mechanical hemming and welding.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces expensive adhesive materials and curing equipment with simpler, more cost-effective mechanical operations that achieve the same functional results without requiring specialized materials.

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

3Ease of manufacture

If butt welding of two sheets is used, then production cost is reduced, but dimensional stability and geometric precision worsen

Engineering Contradiction:
Improveproduction costVSAvoidgeometric precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention performs preliminary folding of the flange to create a precise geometric configuration before welding, ensuring that the welding operation itself does not introduce geometric deviations and that dimensional stability is maintained throughout the process.

Inventive Principle:
Principle #10Preliminary action

4Device complexity

If incident positioning of second sheet on connection flange is used, then device complexity is reduced, but dimensional stability worsens due to hinge formation

Engineering Contradiction:
Improvedevice complexityVSAvoiddimensional stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The invention uses asymmetric positioning where the second sheet is offset relative to the connection flange, which prevents the formation of hinge structures that would compromise dimensional stability, while maintaining a relatively simple welding configuration.

Inventive Principle:
Principle #4Asymmetry

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 approach reduces production costs, eliminates the need for sealing facilities and adhesive equipment, enhances dimensional stability by avoiding hyperstatic configurations, and prevents geometric deviations, resulting in a more reliable and cost-effective manufacturing process for motor vehicle bodywork components.

Implementation Method 1

A method involving laser welding of two metal sheets with connection flanges

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3181285B1A bodywork or chassis component for a motor vehicle, particularly a door for a motor vehicle
Publication Date: 2018.08.29 CENTRO RICERCHE FIAT SCPA
  • EP3181285B1 patent drawingFigure 1
  • EP3181285B1 patent drawingFigure 2
  • EP3181285B1 patent drawingFigure 3

AI summary

A bodywork (D) or chassis component for a motor vehicle is described which includes a first sheet (1) having a first connection flange (3) and a second sheet (2) having a second connection flange (4), the first sheet (1) and the second sheet (2) being joined in correspondence of the respective first connection flange (3) and second connection flange (4), wherein: - the first connection flange (3) is a flange folded back towards the first sheet (1) so as to define a valley (5) with the first sheet (1), - the second connection flange (4) is overlapped to said first connection flange (3) for an overlap length (L, L') and it is at least in part joined to said first connection flange (3) by means of a welding (W) at that joins a perimeter edge (E2) of a second connection flange (4) to a side of the first connection flange (20UT) external with respect to said valley (5), and - wherein the first connection flange (3) and the second connection flange (4) are parallel to one another in correspondence of the overlap length (L, L'). It is furthermore defined according to the invention a method for manufacturing of the aforementioned component.