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FIXED LOW WEAR COMB DESIGN FOR UNIDIRECTIONAL PREPREG CMC TAPES

IP.com Disclosure Number: IPCOM000240160D
Publication Date: 2015-Jan-07
Document File: 5 page(s) / 157K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention is related to a comb separating device for use in automated tape laying (ATL) and automated fiber placement (AFP) machines.

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    The invention is related to a comb separating device for use in automated tape laying (ATL) and automated fiber placement (AFP) machines.

BACKGROUND

    Lightweight fiber composites hold great promise for the aircraft industry. Fiber composites provide a significant improvement in specific strength and stiffness over conventional metal alloys. Better specific strength and stiffness translates into weight savings, which translates into fuel savings and lower operating costs.

    A recent development is making parts from a ceramic matrix composite (CMC). One CMC form is a silicon carbide matrix that weighs a third of advanced alloys but reacts to stresses like a metal and can perform at temperatures as high as 2400° F. The material is going to be used to make aircraft parts such as engine shrouds among others. The method of forming the parts is very similar to the method used for making parts from carbon fiber polymer composites. This process includes making a prepreg tape and laying it using a tape laying machine.

    Prepreg may be applied to a mold or tooling in a variety of ways depending upon the size of the part and the surface complexity. Automated prepreg application procedures are particularly desirable for fabricating large composite parts, such as aircraft parts. One such automated process involves the use of automated tape laying machines that are commonly

 

FIXED LOW WEAR COMB DESIGN FOR UNIDIRECTIONAL PREPREG CMC TAPES

TECHNICAL FIELD



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referred to as "automated tape layers". Automated tape layers tend to be large gantry style machines in which a movable tape delivery head mechanism is mounted between parallel rails. The tape delivery head is generally computer controlled and can be moved about multiple axis to provide delivery of a prepreg tape to a variety of mold shapes.

    Fabrication by automated fiber placement (AFP) is another very similar method. During AFP, a fiber placement head deposits bundles of fibers ("tows") onto a rotating mandrel tool. The tows are narrower and more easily manipulated than tape. AFP is most effective when placing material on a curved or contoured surface.

    The device used in these automated tape laying machine heads to set the spacing between the individual tows is called a comb. Typically, this comb has adjustable spacing between the teeth of the comb. In most machines the comb is used for separating polymer matrix composites and it is made from metal. These metal teeth are not suitable for use with CMC tape due to the extreme hardness of the composite causing great wear to the metal teeth. The wear of the metal means teeth having short lifespans and manufactured parts that are contaminated with metal worn off from the teeth. The ceramic fiber tows are abrasive and metal from a comb will coat the tows as it passes through the comb. The metal will become incorporated into the final composite and can cause undesired reactions which may compromise final composite properties.

    One att...