Flat Vehicle Bodywork Section with Electrophoretic Coated Sheet Metal

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Solution Overview

Problem

Existing vehicle body parts made from composite materials with sheet metal outer skins have unfavorable weight/stiffness ratios and require complex and costly painting processes, often necessitating additional insulation and decoupling layers, which increase logistical efforts and costs.

Innovation Solution

A flat vehicle body part composed of a composite material with an aluminum or steel sheet metal outer skin coated on both sides via electrophoretic deposition for paint adhesion, paired with a support structure coated with fiber-reinforced synthetic resin layers, allowing for simple and cost-effective painting and improved weight/stiffness ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an aluminum shell with steel frame crossbeams is used, then the vehicle body part has high strength, but the weight-to-stiffness ratio becomes unfavorable and additional insulation is required

Engineering Contradiction:
ImprovestrengthVSAvoidweight-to-stiffness ratio
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The invention uses a composite structure consisting of an aluminum or steel sheet outer skin combined with a foam core or honeycomb core. This composite material approach provides both the strength of metal and the lightweight properties of the core material, achieving a favorable weight-to-stiffness ratio while maintaining structural integrity

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention employs thin sheet metal (0.2 to 0.9 mm thick) as the outer skin of the body part. The thin metal shell provides structural strength and surface quality while minimizing weight, working in conjunction with the core material to achieve the desired strength-to-weight ratio

Inventive Principle:
Principle #30Flexible shells and thin films

2Weight of moving object

If a carbon fiber shell is used, then the vehicle body part achieves high strength and low weight, but it becomes very difficult to paint and very expensive

Engineering Contradiction:
ImproveweightVSAvoidpainting difficulty and cost
Core Design Contradiction:
Weight of moving objectVSEase of manufacture

Solution Approach 1:

The invention uses conventional sheet metal (aluminum or steel) instead of expensive carbon fiber, providing a cost-effective alternative that maintains structural integrity while being much easier and cheaper to paint using standard manufacturing processes

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

Solution Approach 2:

The invention changes the material parameter from carbon fiber to conventional sheet metal, which fundamentally alters the manufacturing and painting characteristics while maintaining acceptable weight and strength properties for vehicle body parts

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the vehicle body part is painted at the vehicle manufacturer's facility, then the painting quality is maintained, but significant logistical effort and cost are involved

Engineering Contradiction:
Improvepainting qualityVSAvoidlogistical effort
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The invention enables pre-painting of vehicle body parts at the supplier's facility before delivery to the vehicle manufacturer. This preliminary action allows painting to be completed in advance using standardized processes, reducing logistical complexity and enabling just-in-sequence production while maintaining quality standards

Inventive Principle:
Principle #10Preliminary action

4Object-affected harmful factors

If additional insulation and decoupling layers are added, then acoustic properties and crash resistance are improved, but the device complexity and cost increase

Engineering Contradiction:
Improveacoustic properties and crash resistanceVSAvoidnumber of layers
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The foam core or honeycomb core serves multiple functions simultaneously: it provides structural support, acoustic insulation, and crash resistance. This multi-functionality eliminates the need for separate insulation layers and decoupling layers, reducing overall device complexity while maintaining protective performance

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

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 solution enables lightweight, rigid, and easily paintable vehicle body parts with improved acoustic properties and crash resistance, reducing the need for additional insulation and decoupling layers, facilitating just-in-sequence production and cost savings by allowing pre-painting at the supplier level.

Implementation Method 1

The outer skin sheet metal is coated on both sides with a layer formed by electrophoretic deposition, also known as a cathodic dip coating (CDD) layer, which serves as an adhesion promoter for paint.

Methodology Applied
Scientific EffectElectrophoretic deposition: Electrophoretic Deposition

Data Source

PatentEP3168116B1Flat vehicle bodywork section
Publication Date: 2021.05.26 WEBASTO AG
  • EP3168116B1 patent drawingFigure 1~2

AI summary

The invention relates to a planar vehicle body part comprising a composite material with an outer skin (6) formed from a sheet metal panel and a support structure (12) which includes a core (14) and which is provided on the side facing the outer skin (6) with a first fiber-reinforced synthetic resin layer (10) and on the side facing away from the outer skin (6) with a second fiber-reinforced synthetic resin layer (16). The sheet metal of the outer skin (6) has a coating (8) on both sides formed by electrophoretic deposition and has a thickness of 0.2 to 0.9 mm.