Microwave Heating Compression for Composite Materials

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Solution Overview

Problem

Existing methods for forming composite materials by microwave heating of thermoplastic particles face challenges in maintaining consistent compressive pressure, leading to air pockets and voids due to the manual adjustment required as the fiber mixture shrinks during heating.

Innovation Solution

Incorporating a temperature-responsive compression element, such as ceramic elements with positive thermal expansion coefficients or shape memory alloy (SMA) wires, within a receptacle to automatically apply and increase compressive force during microwave heating, ensuring consistent pressure and eliminating voids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If manual tightenable brackets are used to provide compressive pressure, then compressive pressure can be applied to the fiber mixture, but user intervention is required and the heating process must be stopped for adjustment

Engineering Contradiction:

Improvecompressive pressureVSAvoidautomatic pressure application

Core Design Contradiction:

Stress or pressureVSExtent of automation

Solution Approach 1:

The patent employs a spring mechanism whose compression force parameter automatically adjusts in response to temperature changes during microwave heating. As the thermoplastic material shrinks during heating, the spring compresses further, automatically increasing the compressive pressure without requiring manual intervention or process interruption.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The spring-based compression system is self-regulating and automatically adapts to the volume changes of the fiber mixture during heating. The system serves itself by using the thermal contraction of the material to drive the spring mechanism, eliminating the need for external manual adjustment or external power sources.

Inventive Principle:

Principle #25Self-service

2Ease of manufacture

If the fiber mixture is heated without compressive pressure, then the heating process is simple, but air pockets and void volumes are likely to be present

Engineering Contradiction:

Improveheating process simplicityVSAvoidcomposite material density

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent dynamically changes the compression parameter during the heating process. The spring mechanism automatically adjusts the compressive force based on the material's thermal contraction, ensuring continuous removal of air pockets and voids while maintaining a simple overall process requiring no manual intervention.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If compressive pressure is applied to maintain consistent pressure during heating, then air pockets are avoided, but the apparatus must be adjusted as the mixture decreases in volume

Engineering Contradiction:

Improvecompressive pressure consistencyVSAvoidprocess adjustment time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The spring-based system automatically compensates for volume changes without requiring external adjustment. The spring's elastic properties allow it to self-regulate the compressive force in real-time as the material contracts during heating, eliminating the need for manual intervention and process delays.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The compression force parameter is dynamically adjusted through the spring mechanism's physical response to temperature changes. As the thermoplastic material contracts during heating, the spring compresses further, automatically maintaining consistent compressive pressure throughout the heating process without time loss.

Inventive Principle:

Principle #35Parameter changes

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

The solution enables active compression and automatic tightening of the fiber mixture, preventing voids and ensuring a uniform composite material by maintaining consistent compressive pressure throughout the heating process, enhancing the efficiency and quality of composite material formation.

Implementation Method 1

at least one ceramic element having a positive thermal expansion coefficient... configured to increase compressive force applied by the compression brackets to the mixture in response to microwave heating

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

at least one shape memory alloy (SMA) wire... configured to increase compressive force applied by the compression brackets to the mixture in response to microwave heating

Methodology Applied

Scientific EffectShape memory alloy effect: Shape Memory Alloy

Implementation Method 3

microwave heating the mixture and the temperature responsive compression element, causing the thermoplastic to melt

Methodology Applied

Scientific EffectDielectric heating: Dielectric Heating

Data Source

PatentUS11577471B2Methods to improve compression during microwave heating

Publication Date: 2023.02.14 TOYOTA JIDOSHA KK

AI summary

Methods for microwave melting of fiber mixtures to form composite materials include placing the fiber mixture in a receptacle located in a microwave oven. The methods further include microwave heating the mixture, causing a heat activated compression mechanism to automatically increase compressive force on the mixture, thereby eliminating air and void volumes. The heat activated compression mechanism can include a shape memory alloy wire connecting first and second compression brackets, or one or more ceramic blocks configured to increase in volume and thereby increase compression on the mixture.