Induction-Heated Thermoplastic Patch Consolidation With Metal Plates

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Solution Overview

Problem

Existing methods for joining thermoplastic materials lack efficiency and require high pressure, making them inefficient and costly for repairing or manufacturing aircraft components.

Innovation Solution

A method involving induction heating and low-pressure consolidation of thermoplastic bodies using induction heating coils and stainless steel heating plates to bond thermoplastic components, utilizing fiber-reinforced thermoplastic materials and a vacuum bag for compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional heating methods are used to join thermoplastic materials, then the bonding process can be completed, but the process is time-consuming and less efficient

Engineering Contradiction:
Improvebonding efficiencyVSAvoidheating time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent replaces conventional thermal conduction heating with induction heating technology. The induction heating coil generates electromagnetic fields that directly induce eddy currents in the thermoplastic material and metal plates, converting electromagnetic energy directly into heat within the workpiece. This eliminates the need for external heat sources and thermal conduction, dramatically reducing heating time and improving bonding efficiency.

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

Solution Approach 2:

The patent changes the heating method from thermal conduction to electromagnetic induction, fundamentally altering the heating parameter mechanism. By using induction heating, the material is heated internally and simultaneously through electromagnetic fields, achieving rapid temperature rise and efficient bonding in a fraction of the time required by conventional methods.

Inventive Principle:
Principle #35Parameter changes

2Strength

If high pressure is applied to consolidate thermoplastic materials, then stronger bonding is achieved, but the equipment complexity and operational difficulty increase

Engineering Contradiction:
Improvebond strengthVSAvoidpressing system complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent introduces metal plates as intermediary elements between the heating coil and the thermoplastic materials. These metal plates serve multiple functions: they concentrate and distribute the induction heating uniformly, provide mechanical pressing force through thermal expansion, and facilitate heat distribution without requiring complex high-pressure equipment. The metal plates act as mediators that transform electromagnetic energy into both thermal and mechanical effects.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the pressure application method from direct mechanical high-pressure systems to a thermal expansion-based pressing mechanism. The metal plates, when heated by induction, expand thermally and automatically apply consistent pressure to the thermoplastic materials. This parameter change from mechanical pressure to thermal expansion pressure simplifies the equipment while maintaining effective bonding strength.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If conventional heating methods are used, then uniform heating is difficult to achieve, but switching to induction heating requires specialized equipment

Engineering Contradiction:
Improveheating uniformityVSAvoidheating system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The metal plates function as intermediary heat distribution elements that receive concentrated electromagnetic energy from the induction coil and distribute it uniformly across the thermoplastic material surfaces. This intermediary mechanism ensures uniform heating and consistent bonding quality while keeping the heating system configuration relatively simple and manageable.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Achieves efficient bonding of thermoplastic components at low pressure, reducing energy consumption and costs while maintaining structural integrity.

Implementation Method 1

The consolidating includes concurrently induction heating the thermoplastic patch, the thermoplastic aircraft component and the metal plate using an induction heating coil

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Implementation Method 2

The induction heating may include exciting at least some of the fibers in the thermoplastic patch, at least some of the fibers in the thermoplastic aircraft component and at least some material of the metal plate with eddy currents generated by the induction heating coil

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

The metal plate may be induction heated to provide a heated metal plate. The consolidating may also include conduction heating the stack with heat energy from the heated metal plate

Methodology Applied
Scientific EffectConduction heating: Conduction (thermal)

Data Source

PatentEP4501597B1Consolidating thermoplastic material with induction heating coil and heating plate(s)
Publication Date: 2026.05.13 ROHR INC
  • EP4501597B1 patent drawingFigure 1~2
  • EP4501597B1 patent drawingFigure 3~4
  • EP4501597B1 patent drawingFigure 5

AI summary

A repair method comprises arranging a thermoplastic patch (40) on a thermoplastic aircraft component (38), each including a thermoplastic matrix with fibres, arranging a metal plate (58B) against the patch (40) and the aircraft component (38), and consolidating the patch (40) and the aircraft component (38) by concurrently induction heating the patch (40), the aircraft component (38) and the metal plate (58B). Preferably, the induction heating involves generating eddy currents to excite the fibres in the thermoplastic patch (40), the fibres in the thermoplastic aircraft component (38). Meanwhile, the heated metal plate (58B) heats the patch (40) and aircraft component (38) by conduction. A second metal plate (58A) may be provided on an opposite side to the first. Preferably, the patch (40), aircraft component (38) and the metal plate(s) (58A, 58B) are provided in a vacuum bag (70) used to apply pressure during consolidation.