Embossed Workpiece Joint for Thermal Joining of Unequal Thickness Parts

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Solution Overview

Problem

Existing methods for producing composite workpieces with large differences in thickness are limited by thermal joining issues and require complex construction measures, making it difficult to achieve reliable joints, especially with unfavorable material pairings.

Innovation Solution

A method involving a thermal joining process where one workpiece is reduced in thickness at the joining section through embossing, allowing for a material bond between workpieces with significant thickness differences, and optionally using a surface coating to enhance joining and corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thermal joining methods are used to connect workpieces with large thickness differences, then material bond is achieved, but joining reliability deteriorates due to thermal issues and unfavorable material pairings

Engineering Contradiction:
Improvematerial bondVSAvoidjoining reliability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies local quality by creating a localized thickness reduction (indentation) at the joining section of the first workpiece. This indentation is formed only in the specific joining area, allowing the thickness to be reduced locally while maintaining the original thickness elsewhere. This enables reliable thermal joining at the localized area without requiring complex global modifications to the workpiece geometry.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by forming the indentation in the first workpiece before the actual thermal joining process. This pre-preparation of the joining geometry allows the thermal joining to proceed more reliably, as the indentation is already in place to facilitate proper contact and heat distribution between the workpieces with different thicknesses.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If workpieces with large thickness differences are joined directly without thickness reduction, then manufacturing process is simple, but joining reliability deteriorates

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidjoining reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

Instead of reducing the thickness of the entire first workpiece, the patent applies local quality by creating an indentation only in the joining section. This localized modification maintains manufacturing simplicity while achieving the necessary thickness reduction only where required for reliable joining, avoiding the need to process the entire workpiece.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The indentation is formed as a preliminary action before joining, preparing the joining geometry in advance. This approach maintains ease of manufacture by using a simple forming process rather than complex machining, while ensuring reliable joining conditions are established before the thermal joining process begins.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the first workpiece is reduced in thickness at the joining section through embossing, then joining reliability of workpieces with thickness differences is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvejoining reliabilityVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by forming an indentation only in the joining section of the first workpiece, rather than modifying the entire workpiece. This localized approach improves joining reliability where needed while minimizing the overall complexity of the manufacturing process, as only a specific area requires the embossing operation.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The indentation is created as a preliminary action using embossing or similar forming processes, which are relatively simple operations compared to alternative methods like machining or removal. This preliminary preparation simplifies the overall process by establishing the correct joining geometry before the thermal joining takes place.

Inventive Principle:
Principle #10Preliminary action

4Strength

If conventional joining methods are used for unfavorable material pairings, then joining is attempted, but corrosion resistance deteriorates due to uncontrolled material transition

Engineering Contradiction:
Improvejoint connectionVSAvoidcorrosion tendency
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a controlled material transition zone through the indentation at the joining section. This localized geometric modification influences the material flow and mixing during thermal joining, creating a more controlled transition between different materials (e.g., aluminum and steel). The controlled transition reduces the formation of corrosive galvanic cells by limiting the extent and distribution of the mixed material zone.

Inventive Principle:
Principle #3Local quality

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

Enables reliable joining of workpieces with large thickness variations, improves joining of difficult material pairings like aluminum and steel, and reduces corrosion tendencies by controlling the material transition at the joint, while simplifying the process and reducing additional manufacturing steps.

Implementation Method 1

the material of the joining partners to be joined is heated to above the liquidus temperature

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 2

The molten phases of both workpieces mix and solidify after cooling to form a material bond

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

the first workpiece is provided with an indentation adjoining the end face, at least in the joining section, whereby the thickness of the first workpiece is reduced in the area of the end face

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 4

optionally using a surface coating to enhance joining and corrosion resistance

Methodology Applied
Scientific EffectSurface coating: Coatings

Data Source

PatentEP3600756B1Method of producing a workpiece composite, and workpiece composite
Publication Date: 2021.09.01 BAYERISCHE MOTOREN WERKE AG
  • EP3600756B1 patent drawingFigure 1~2
  • EP3600756B1 patent drawingFigure 3~4
  • EP3600756B1 patent drawingFigure 5~6

AI summary

The invention relates to a workpiece composite (1) and a method for producing a workpiece composite (1) comprising at least two workpieces (2, 3). A first workpiece (2) and a second workpiece (3) are positioned relative to each other, and a bonded connection (5) between the end face (6) of the first workpiece (2) and the second workpiece (3) is formed in a joint section (4) by means of a thermal joining method. Prior to forming the bonded connection (5), the first workpiece (2) is provided with an embossing (7), which adjoins the end face (6), at least in the joint section (4), whereby the thickness of the first workpiece (2) is reduced in the region of the end face (6).