Prepreg Tape Slitting with Local Heating to Eliminate Voids

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Solution Overview

Problem

Existing prepreg sheet materials often contain voids and unwetted fibers, leading to issues such as breaks, fraying, and defects in slit tape production, particularly in the production of aircraft components with tight width tolerances.

Innovation Solution

A method and apparatus that involves localized heating of prepreg sheet materials to a temperature where the matrix resin becomes tacky or flowable, allowing it to fill voids and wet unwetted fibers, followed by cooling, to reduce or eliminate these defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If continuous manufacturing methods are used for slit tape production, then productivity is improved, but the presence of voids and unwetted fibers increases leading to breaks and defects

Engineering Contradiction:

Improvecontinuous manufacturing speedVSAvoidslit tape quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by heating the prepreg material before slitting to eliminate voids and ensure complete resin impregnation. The heating zone is positioned upstream of the slitting knives, allowing the resin to become tacky and fill voids before the cutting operation, thereby preventing breaks and defects during high-speed continuous manufacturing

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the temperature parameter of the prepreg material by introducing a controlled heating zone. The temperature is elevated to a specific range that makes the resin tacky without causing premature curing, enabling void elimination while maintaining the material's processability during continuous production

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If slitting is performed on prepreg material with voids, then manufacturing precision deteriorates due to breaks and fraying, but adding heating equipment increases device complexity

Engineering Contradiction:

Improveslit tape width toleranceVSAvoidheating and cooling system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by providing heating only in the specific zone where void elimination is needed, rather than heating the entire material continuously. The heating elements are localized to the area immediately preceding the slitting knives, and cooling is applied only where needed to reset the material properties, minimizing energy consumption and device complexity while maintaining precision

Inventive Principle:

Principle #3Local quality

3Reliability

If heating temperature is increased to eliminate voids, then reliability improves, but the risk of premature curing increases

Engineering Contradiction:

Improvevoid elimination effectivenessVSAvoidpremature curing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses preliminary action by applying heat only for the brief period needed to make the resin tacky and fill voids, then immediately cooling the material before it reaches the slitting zone. This controlled, temporary heating eliminates voids while the subsequent cooling prevents the temperature from reaching the curing threshold

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements periodic action through the cyclic heating and cooling process. The material passes through a heating zone temporarily, then immediately through a cooling zone, creating a periodic temperature variation that achieves void elimination while preventing sustained high temperatures that would cause premature curing

Inventive Principle:

Principle #19Periodic action

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 method significantly reduces the presence of voids and unwetted fibers, improving the quality of slit tape production by minimizing breaks, fraying, and defects, especially in continuous manufacturing processes.

Implementation Method 1

a heating element positioned to heat only a cross-sectional area of the prepreg sheet material to a temperature at which the matrix resin becomes tacky or flowable

Methodology Applied

Scientific EffectHeating: Heating