Clinched Composite Joint Structure for Low-Force Sheet Joining

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Solution Overview

Problem

Existing clinching processes for forming component composites require high forming forces and specific material pairings, limiting their application in series production and making it difficult to connect components in limited spaces due to the need for large forming tools and restrictive material choices.

Innovation Solution

A clinching method that uses a twisted arrangement of the forming die and punch to create a recess in the softer component, allowing the stronger component to form a protuberance that fills the recess, forming an undercut for secure bonding with reduced forming forces and enabling connections in previously inaccessible areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional clinching processes are used to form component composites, then firm connections can be achieved, but high forming forces (not less than 100 KN) are required

Engineering Contradiction:
Improveconnection strengthVSAvoidforming force
Core Design Contradiction:
StrengthVSForce

Solution Approach 1:

The patent inverts the conventional clinching approach by pressing the softer component into the harder component instead of pressing the harder component into the softer one. This inversion allows the softer material to deform and flow into the harder component's surface, creating a mechanical interlock with significantly reduced forming forces while maintaining connection strength.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the material parameter pairing by deliberately selecting a softer component (lower yield strength) to be pressed into a harder component (higher yield strength). This parameter change in material hardness relationship enables the formation of effective mechanical interlocks with reduced forming forces, as the softer material can more easily deform and adapt to the harder component's surface geometry.

Inventive Principle:
Principle #35Parameter changes

2Strength

If large forming tools are used to apply high forming forces, then component composites can be formed, but the tools cannot be used in limited spaces

Engineering Contradiction:
Improveconnection strengthVSAvoidforming tool size
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

By inverting the clinching process to press the softer component into the harder one, the required forming forces are dramatically reduced. This allows the use of smaller, more compact forming tools that can access limited spaces while still achieving sufficient connection strength through the mechanical interlock created by the softer material deforming into the harder component.

Inventive Principle:
Principle #13The other way round (Inversion)

3Strength

If identical sheet materials or soft sheets are used in conventional clinching, then firm connections can be formed, but the choice of material pairings is limited

Engineering Contradiction:
Improveconnection strengthVSAvoidmaterial pairing flexibility
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent fundamentally changes the material parameter pairing strategy by using a softer component (lower yield strength) pressed into a harder component (higher yield strength). This approach expands material pairing flexibility because it allows dissimilar materials with different hardness levels to be effectively joined, whereas conventional clinching requires similar or specific material pairings to achieve firm connections.

Inventive Principle:
Principle #35Parameter changes

4Force

If the softer sheet metal is made thinner to reduce punch forces, then forming forces are reduced, but the sheet thickness choices are constrained

Engineering Contradiction:
Improvepunch forceVSAvoidsheet thickness
Core Design Contradiction:
ForceVSLength of stationary object

Solution Approach 1:

By inverting the clinching process to press the softer component into the harder one, the patent reduces the required punch forces without constraining sheet thickness choices. The softer material's ability to deform and flow into the harder component creates effective mechanical interlocks even with thicker sheets, eliminating the need to thin the softer material to reduce forming forces.

Inventive Principle:
Principle #13The other way round (Inversion)

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 method allows for the formation of component composites with low forming forces, enabling connections in limited spaces and allowing for the use of optimized material pairings, reducing the size of forming tools and maintaining mechanical resilience while keeping manufacturing costs economical.

Implementation Method 1

the joining area having a plastic deformation area by means of which the first and the second component are held in the joining area by cold deformation

Methodology Applied
Scientific EffectCold forming: Cold-forming

Implementation Method 2

the base material of the first component having the recess has a lower yield strength than the base material of the second component

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 3

the deformed material forms a protuberance projecting from the second component, which protrudes into the recess and forms a contact area between the first and second components with an undercut

Methodology Applied
Scientific EffectMaterial flow: Deformation

Implementation Method 4

The forming area is cold formed by clinching using a forming tool

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3703881B1Composite component and control unit
Publication Date: 2023.07.05 ROBERT BOSCH GMBH
  • EP3703881B1 patent drawingFigure 1~2
  • EP3703881B1 patent drawingFigure 3
  • EP3703881B1 patent drawingFigure 4a~4b

AI summary

The invention relates to a composite component comprising at least a first component and a second component which are joined together in a joint region, wherein the joint region has a plastic deformation region by means of which the first component and the second component are held in the joint region by cold deformation with a holding force directed towards one another. In the plastic deformation region the first component has a recess which is at least partially filled with deformed material from the second component. The deformed material forms a protuberance which projects from the second component, protrudes into the recess and forms a contact region between the first component and the second component with an undercut. The undercut counteracts a detachment of the components in the event of a force being applied to the joint region. The deformation region is cold-formed by clinching. The main material of the first component having the recess has a lower yield strength than the main material of the second component, which at least partially fills the recess with deformed material. Furthermore, at least in the joint region the first component and the second component are in the form of metal sheets or metal-sheet-like parts, and a main sheet thickness of the second component is greater than a main sheet thickness of the first component.