Laser Lap Welding of Dissimilar Stainless Steel Appliance Panels

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Solution Overview

Problem

Connecting thin sheet metal plates made of different stainless steel materials, such as ferritic and austenitic stainless steels, in household appliances like gas stoves poses challenges due to low connection strength and corrosion risks, especially when one plate serves as an outer cladding panel requiring a method that maintains visual appearance and prevents deformation.

Innovation Solution

The method involves overlap welding using a laser welding device, aligning the laser beam at an angle of 45° to 90° to penetrate through one plate and create a strong, rust-free connection between thin sheets, preferably with spot welds distributed in a hexagonal pattern, to ensure a reliable and visually undisturbed joint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional welding methods are used to connect thin sheet metal plates made of different stainless steels, then connection strength is improved, but corrosion resistance deteriorates and the visual appearance of the outer panel is impaired

Engineering Contradiction:
Improveconnection strengthVSAvoidcorrosion risk and visual impairment
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent replaces traditional mechanical welding processes with laser welding technology. The laser beam provides precise, localized heating that melts and fuses the thin sheet metal plates without requiring mechanical pressure or complex welding equipment, thereby achieving strong connections while minimizing distortion and corrosion risk

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the specific parameters of laser welding including beam power, focal position, and scanning speed to optimize the welding process. By adjusting these parameters, the process achieves adequate penetration and connection strength for thin sheets while controlling heat input to prevent excessive melting, distortion, and corrosion

Inventive Principle:
Principle #35Parameter changes

2Strength

If conventional welding processes are applied to thin sheet metal plates with thickness less than 1 mm, then connection strength is improved, but deformation and loss of optical properties occur

Engineering Contradiction:
Improveconnection strengthVSAvoiddeformation and optical property retention
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent replaces conventional mechanical welding with laser welding, which provides non-contact, localized heating. This substitution eliminates mechanical pressure and reduces overall heat input, preventing deformation of thin sheets while maintaining connection strength and preserving the optical properties of outer panels

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The laser beam concentrates energy in a very small focal area, creating localized melting only at the joint region. This local quality approach ensures that the thin sheet metal plates are welded strongly at the connection point while the surrounding areas, including the visible outer panel surfaces, remain undeformed and retain their optical properties

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If adhesive connection is used to connect sheet metal plates made of different stainless steels, then visual appearance is maintained, but production efficiency is reduced

Engineering Contradiction:
Improvevisual appearanceVSAvoidproduction efficiency
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent replaces adhesive bonding with laser welding, transitioning from a chemical joining process to a thermal-mechanical process. This substitution enables automated, rapid joining with immediate strength development, significantly improving production efficiency while the localized nature of laser welding preserves the visual appearance of outer panels

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Laser welding provides continuous, automated joining action along the joint line, eliminating the multiple steps required for adhesive application, curing, and inspection. This continuous process dramatically increases production efficiency while maintaining the aesthetic quality of the finished product

Inventive Principle:
Principle #20Continuity of useful action

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 provides a strong, reliable connection that minimizes the risk of corrosion and deformation while maintaining the aesthetic appearance of the appliance, with the added benefit of automating the welding process for increased production efficiency.

Implementation Method 1

overlap welding using a laser welding device, aligning the laser beam at an angle of 45° to 90° to penetrate through one plate and create a strong, rust-free connection

Methodology Applied
Scientific EffectLaser beam welding: Laser Beam Welding

Data Source

PatentEP2777864B1Method of connecting two panels of sheet metal of a household appliance using overlapping laser welding of different stainless steels ; corresponding household appliance
Publication Date: 2016.04.20 BSH HAUSGERATE GMBH
  • EP2777864B1 patent drawingFigure 1~2
  • EP2777864B1 patent drawingFigure 3

AI summary

The invention relates to a method for connecting two sheet metal plates (1, 3) of a household appliance (4), in particular a gas stove, one of the sheet metal plates (1, 3) being made of a first type of stainless steel and the other sheet metal plate (3, 1) being made of stainless steel of a second type different from the first type, and wherein the sheet metal plates (1, 3) are joined together by lap welding by means of a laser welder.