Liftgate Reinforcement Thermal Joining Without Adhesives or Fasteners

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Solution Overview

Problem

The existing methods for attaching metal reinforcements to thermoplastic liftgate inner panels, such as using fasteners or adhesives, increase production time and complexity, and create recycling difficulties due to adhesive residue.

Innovation Solution

A method using mechanical locks formed by embedding a portion of fiber-filled polymer material into apertures of reinforcement brackets, eliminating the need for adhesives and fasteners, with the polymer material being melted and cured to create a strong connection between the liftgate panel and reinforcement brackets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If fasteners are used to attach metal reinforcements to thermoplastic liftgate inner panels, then the connection strength is improved, but the production time and complexity increase

Engineering Contradiction:
Improveconnection strengthVSAvoidproduction time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The patent replaces the mechanical fastening system (screws, clips, or other removable fasteners) with a thermal bonding process where molten thermoplastic material is injected into apertures of the reinforcement bracket, creating a permanent mechanical interlock through phase change and cooling. This eliminates the need for separate fastener components and assembly steps.

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

Solution Approach 2:

The invention utilizes the phase transition of thermoplastic material from solid to molten state and back to solid. The polymer is heated to melt and flow into the apertures of the reinforcement bracket, then cooled and cured to form a strong mechanical lock that permanently bonds the reinforcement to the panel.

Inventive Principle:
Principle #36Phase transitions

2Device complexity

If adhesives are used to attach metal reinforcements to thermoplastic liftgate inner panels, then the production complexity is reduced, but the recycling difficulty increases due to adhesive residue

Engineering Contradiction:
Improveproduction complexityVSAvoidrecycling difficulty
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the chemical bonding system (adhesives) with a thermal-mechanical bonding process. Instead of using adhesive chemicals to bond the reinforcement, the system uses heat to melt thermoplastic material that flows into and mechanically interlocks with the reinforcement bracket apertures, creating a purely physical bond without chemical residues.

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

Solution Approach 2:

The invention changes the bonding mechanism from chemical (adhesive-based) to thermal-mechanical (heat and pressure-based). By controlling temperature parameters, the thermoplastic material transitions to a molten state for bonding, then solidifies to create a permanent connection, eliminating the need for adhesive chemicals and their associated recycling issues.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If multiple attachment methods (fasteners and adhesives) are used, then the connection reliability is improved, but the manufacturing cost increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the functions of multiple attachment methods (fasteners and adhesives) into a single integrated thermal bonding process. The molten thermoplastic material simultaneously provides structural support, connection strength, and permanent bonding in one step, eliminating the need for separate fastener installation and adhesive application processes.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The thermoplastic material serves multiple functions simultaneously: it acts as the bonding agent, the structural connector, and the sealing medium. The material self-bonds to the reinforcement bracket through the thermal-mechanical process, eliminating the need for separate bonding agents or additional assembly steps.

Inventive Principle:
Principle #25Self-service

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 complexity and costs, while ensuring a strong and reliable connection without adhesive residue, facilitating easier recycling and improved manufacturing efficiency.

Implementation Method 1

a portion of the fiber filled polymer material curing in the at least one aperture of the reinforcement bracket

Methodology Applied
Scientific EffectMelting and curing of polymer material: Melting

Implementation Method 2

joining metal reinforcements to thermoplastic liftgate inner panels using various thermal joining techniques

Methodology Applied
Scientific EffectThermal joining: Heating

Data Source

PatentEP4400344A1Liftgate metallic reinforcement thermal joining to the thermoplastic inner panel
Publication Date: 2024.07.17 MAGNA EXTERIORS INC
  • EP4400344A1 patent drawingFigure 1
  • EP4400344A1 patent drawingFigure 2~3
  • EP4400344A1 patent drawingFigure 4

AI summary

A reinforced lift gate panel arrangement that includes a lift gate panel formed of fiber filled polymer material. The lift gate panel has a structural side with a connection surface region. The arrangement further includes at least one reinforcement bracket with a panel contact side and a tool contact side with at least one aperture formed through the reinforcement bracket that extends from the panel contact side to the tool contact side. There is at least one mechanical lock formed between the lift gate panel and the reinforcement bracket. The mechanical lock is formed by a portion of the fiber filled polymer material curing in the at least one aperture of the reinforcement bracket.