The foregoing and other advantages and features of the invention, and the manner in which the same are accomplished, will become more readily apparent upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings which illustrate preferred and exemplary embodiments, but which are not necessarily drawn to scale, wherein:
The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in several different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
Referring now to the drawings, and in particular, to
The apparatus 10 further comprises a first compacting component 34 for compacting and pressing the prepreg material onto the backing paper 12 to form a prepreg tube 36 wrapped around the mandrel 18. The compacting component 34 is preferably in the form of orbiting compacting rollers that are located farther downstream from the application wheels 22. Optionally, a radiant or convection heat source (not shown) may be used to soften the prepreg tape upstream of the compacting component to aid in the compaction process. The apparatus may further comprise a cutting component 38 for cutting the prepreg tube 36. Preferably, the cutting component 38 is in the form of a slitter wheel that is used to cut the prepreg tube 36 where the edges of the backing paper meet. The apparatus 10 may further comprise an opener component (not shown) for opening and laying flat the cut prepreg tube 36 to form an output product or roll 40, which when laid out is a substantially flat two layer off-axis composite prepreg material, with backing paper. The prepreg tube 36 is progressively opened to a flat sheet and spooled or wrapped around the output roll 40 which is mounted on a second roll stand 42. Preferably, the output roll has a width of 24 inches and a typical double prepreg thickness of 0.15 inches. However, other suitable widths may also be used. It may be desirable to incorporate another cutting component (not shown) just before the output roll and to use multiple rolls to spool up the output material. For example, the 24-inch width may be cut to go onto four 6-inch wide output rolls. Such a cutting and winding process is commonly used in the industry. The apparatus 10 may further comprise a second compacting component 44 for compacting and pressing the composite prepreg material or tape before it is wrapped around the output roll. In addition, various rollers and heat sources (not shown) may be applied to facilitate the transition from prepreg tube to flat sheet.
A large ply angle, such as 65 degrees, requires a narrower prepreg supply roll as shown in
In another version of the invention, an apparatus for producing a three or more layer off-axis composite prepreg material in tape form is provided. This apparatus comprises a roll of backing paper mounted on a first roll stand, and at least one paper guide adapted to unroll the backing paper and wrap the backing paper around a cylindrical mandrel supported on at least two mandrel stands. This apparatus further comprises a plurality of application wheels equal in number to the number of layers of composite prepreg material to be formed, wherein each application wheel is supported independently of the mandrel and designed to rotate around the mandrel. Within each wheel is mounted a paper stripping roll and one composite prepreg supply roll having prepreg material, where the paper stripping roll and supply roll are on respective axes that are off-axis relative to a normal vector from a centerline of the mandrel. Further, each wheel is designed to lay from the prepreg supply roll a tape layer over the backing paper in a helix orientation around the mandrel. The apparatus further comprises a compacting component for compacting and pressing the prepreg material onto the backing paper to form a prepreg tube wrapped around the mandrel. The apparatus further comprises a cutting component for cutting the prepreg tube. The apparatus further comprises an opener component for opening and laying flat the cut prepreg tube to form a substantially flat three or more layer off-axis composite prepreg material in tape form formed from the backing paper and the composite prepreg, wherein the tape is wrapped around to form an output roll mounted on a second roll stand. The three or more layer off-axis composite prepreg material comprises uni-directional carbon fibers in an uncured resin matrix, wherein the carbon fibers are oriented at an angle of approximately plus between 5 degrees and eighty-five degrees for a first prepreg layer and minus between 5 degrees and eighty-five degrees for a second prepreg layer from a central axis of the backing paper.
In another version of the invention, a method for producing a two layer off-axis composite prepreg material in an output roll or tape form is provided. The method is similar to existing methods that use conventional composite tape lamination machines that continuously knit a tube of material that is then slit and spooled up as a continuous ribbon. The difference is that the method of the invention produces a non-woven product with a much more acute fiber angle than that produced by the knitting process. The method of the invention comprises the steps of first unrolling a roll of backing paper 12 mounted on a first roll stand 14 and wrapping the backing paper around a cylindrical mandrel 18 supported on at least two mandrel stands 20. The method further comprises the step of rotating at least two application wheels 22 co-axially around the mandrel in opposite directions to one another, wherein within each wheel is mounted a paper stripping roll 26 and at least one composite prepreg supply roll 28 having prepreg material, where the paper stripping roll and supply roll are on respective axes 30, 32 that are off-axis relative to a normal vector from a centerline of the mandrel. Each wheel synchronously lays from the prepreg supply roll a prepreg tape in a helix orientation around the mandrel. Each application wheel may include one, two, three, four or more prepreg supply rolls within the wheel. As discussed above, preferably the composite prepreg tape is 6 inches wide. In addition, the method may include one, two, four or more application wheels. The method further comprises the step of compacting and pressing with a first compacting component 34 the prepreg supply roll onto the backing paper to form a prepreg tube 36 wrapped around the mandrel. The method further comprises the step of cutting with a cutting component 38 the prepreg tube. The method further comprises the step of opening and laying flat with an opener component (not shown) the cut prepreg tube to form a substantially flat two layer off-axis composite prepreg material in tape form formed from the backing paper and the composite prepreg. The method further comprises the step of wrapping the composite prepreg tape around to form an output product or roll 40 mounted on a second roll stand 42. The method may further comprise the step prior to the compacting step of heating with a first heater component the prepreg supply roll in order to soften it. The method may further comprise the step prior to the cutting step of heating with a second heater component the prepreg supply roll in order to soften it. Preferably, the temperature used to heat the prepreg supply roll is about less than 150 degrees Fahrenheit, and more preferably, the temperature is 90 degrees Fahrenheit. The method may further comprise the step prior to the wrapping the composite prepreg tape step of compacting and pressing the composite prepreg with a second compacting component 44.
Preferably, the method of the invention results in a two layer off-axis composite prepreg material comprising uni-directional carbon fibers in a resin matrix, where the carbon fibers are oriented at an angle of approximately plus five degrees for a first prepreg layer and minus five degrees for a second prepreg layer from a central axis of the backing paper. In addition, the method of the invention may result in a two layer off-axis composite prepreg material comprising uni-directional carbon fibers in a resin matrix, wherein the carbon fibers are oriented at an angle of approximately plus less than thirty degrees for a first prepreg layer and minus less than thirty degrees for a second prepreg layer from a central axis of the backing paper. In addition, the method of the invention may result in a one layer off-axis composite prepreg material comprising uni-directional carbon fibers in a resin matrix when only one prepreg supply roll within one application wheel is used in the method. The average rate of forming the prepreg composite material output product is about 2000-5000 inches per minute.
The invention provides a method and apparatus that produces rolls of material with a single ply of non-zero fiber orientation or a roll with multiple plies of tape with multiple orientations, such as product with plus 5 degree, minus 5 degree, plus 65 degree, and minus 65 degree plies, all combined in a roll of material. Each layer from such a roll would have strength in multiple directions. The method and apparatus of the invention may also produce rolls of material with a single layer of plus or minus 5 degree oriented material. The use of such off-axis prepreg composite material tape is primarily for fabricating high length-to-width ration parts such as composite wing stringers or spars for aircraft.
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.