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Apparatus and method to improve stress and twist of the tows when depositing for manufacturing composite layers

IP.com Disclosure Number: IPCOM000235662D
Publication Date: 2014-Mar-19
Document File: 4 page(s) / 224K

Publishing Venue

The IP.com Prior Art Database

Abstract

To manufacture composite part, some pre-forms made with composite layers oriented in various directions are processed, molded, cured and consolidated. With current apparatus and process, a twist is created within fiber of 0° layer due to various stress applied on each fiber. When the layer is used in a pre-form and processed to make a composite part, gaps and holes are created within the part. These holes and gaps weaken the part. The following description proposes exploring how to improve key process parameters and a new arrangement for depositing composite layers.

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Page 01 of 4

Apparatus and method to improve stress and twist of the tows when depositing for manufacturing composite layers

Abstract:

To manufacture composite part, some pre-forms made with composite layers oriented in various directions are processed, molded, cured and consolidated. With current apparatus and process, a twist is created within fiber of 0° layer due to various stress applied on each fiber. When the layer is used in a pre-form and processed to make a composite part, gaps and holes are created within the part. These holes and gaps weaken the part. The following description proposes exploring how to improve key process parameters and a new arrangement for depositing composite layers.


1. PROBLEM DESCRIPTION

To manufacture composite part, some pre-forms made with composite layers oriented in various directions are processed, molded, cured and consolidated. The quality of the layers is a huge factor for the quality of the final composite piece.

Figure 1: Schematic illustration of current process

As shown on figure 1, the current process of composite layers manufacturing consists in depositing several tows made of fiber pre-impregnated with resin on one table to form one layer. Each layer is orientated in one direction (0°, 45° or 90° for example).


Page 02 of 4

The tows are provided through several reels aligned side by side which reels off the tows. The tows are deposed on the table (or on previous layers) through several rollers who move along the table to form the layer.

With this apparatus and process, a twist is created within fiber of 0° layer due to various stress applied on each fiber. When the layer is used in a pre-form and processed to make a composite part, gaps and holes are created within the part. These holes and gaps weaken the part.

The solution described here proposed to reduce the stress applied to each tow and to homogenize the stress applied on all the tows.


2. TOW TENSION AFTER THE LAST ROLLER CONSIDERATIONS

The tension applied at each tow has to be more than a ''minimum tension''; the ''minimum tension'' is the tension which allows:


- To put and maintain the tow straight all along the machine
- To allow removing tow geometrical defaults: spooling effects, etc…

To get the best result, a low tow tension has to be required on this kind of apparatus: if the tension is too high, the consequence is a shrinking effect of the 0° layer along the length of the machine.

So the main question is: What is the '' tow tension'' required for this kind of apparatus? Often it is adjusted in real time by the operatorswith their experience, looking at the product manufactured by the machine (width reduction, quality of the 0° layers …).


3. DISTURBANCES THAT MIGHT OCCUR ON THE 0° PROCESS

If there are tow overlaps on the last roller, due to its ''extra radius'' (tow thickness), the external tow will feed to much the machine compare the internal tow; the consequences for this tow are tension lost and extra length (about...