System and Method for Guiding Fibers

This application is a continuation of U.S. patent application Ser. No. 17/632,430, filed Feb. 2, 2022 which is the U.S. National Phase application of PCT International Application No. PCT/US2020/045189, filed Aug. 6, 2020, which claims priority to U.S. Provisional Patent Application No. 62/883,832, filed Aug. 7, 2019, entitled “SYSTEM AND METHOD FOR GUIDING FIBERS,” the contents of all of which are incorporated herein by reference in their entireties.

This invention is in the field of fiber processing equipment, particularly for fibers intended to be used as reinforcement in fiber-reinforced composite materials.

Fiber processing in an industrial setting requires moving fibers, usually in the form of a bundle of fibers, to be guided from one place to another. In the course of such movement, the moving fibers are often required to be guided by being in contact with at least one, and usually more than one unmoving guide, such as an eyelet, or other such guiding surface. The moving fibers thus come into contact with several such static points or surfaces. At those contact points, friction is present and delicate fibers in the bundle tend to break and thus a bundle of fibers (sometimes called a tow) can shred.

According to one aspect of the invention, a fiber guide configured to guide fibers in a fiber processing system is provided. The fiber guide includes a surface defining a plurality of apertures through which fibers can pass in a direction from an upstream side of the surface to a downstream side of the surface, each of the apertures having an inlet positioned to receive fibers from the upstream side of the surface. The plurality of apertures include at least one pair of first and second apertures adjacent to and spaced from one another. The inlet of the first aperture of the at least one pair of first and second apertures is offset from the inlet of the second aperture of the at least one pair of first and second apertures, the offset being in the direction in which the fibers can pass from the upstream side of the surface to the downstream side of the surface. A distance dbetween the inlet of the first aperture and the inlet of the second aperture is larger than a distance dbetween the first aperture and the second aperture measured transverse to the direction in which the fibers can pass.

This invention provides a fiber guide that reduces the fuzz or fluffs and single fiber or yarn or tow breakage and the accompanying deposit and accumulation during the processing of fibers, such as fibers that are used to reinforce composite materials. The fiber guide includes a series of apertures, which may be lined with or have mounted therein, eyelets. The apertures are placed in specified relation to each other. The eyelets themselves have a geometry and material properties.

In the production of fiber reinforced composite materials more specifically, fiber may be glass fiber, carbon fiber, aramid fiber, basalt fiber, or other fiber materials. Those fibers are typically in the form of single yarn, or tow, which is composed of single filaments of fiber. While being processed, as described above, those single filaments tend to break, which causes shredding of the fiber bundle, whether in the form of tow or yarn.

The shredded fibers, in the form of “fuzz” or “fluff,” tend to accumulate and then sometimes break off. The accumulations thus may travel downstream with the fiber bundle, collecting on the processing equipment. Furthermore, the fiber breakage represents lost raw material, which is an economic problem. Thus, this invention provides a way to minimize this fiber breakage, without interfering with the operation of existing fiber processing equipment.

Composite materials require a high number of tows or yarns, each comprised of a bundle of individual fibers, to be processed together. For good performance, yarn should be individually guided. One frequent solution to gather fiber in a specific shape is to use a surface, such a board, in which a number of apertures are formed. The fiber, in form of filaments, or tow or yarn are thus fed through the apertures in the board to guide them in the fiber processing operation. These apertures thus each define a guide surface for each tow or yarn. These apertures may be typically defined by or lined with “eyelets” which act as individual guide surfaces for each tow or yarn. In the discussion that follows, the terms “aperture” and “eyelet” should be understood to refer to types of structures that define an opening or guide opening in the eye board through which the fibers pass during processing.

shows a photograph of a number of various exemplary such eyelets. Although these exemplary eyelets are all generally circular in cross-section, other cross-sectional shapes are possible, such as a square, rectangle, semicircle, etc. Further, while these eyelets are generally annular, they may be open on one side as well, e.g., “U” shape or “C” shape in cross-section, either with curved or straight sides.

The placement of apertures which may be lined with these eyelets in relation to each other on the eye board has been discovered to play a role in the amount of fiber that breaks. These factors will be described in detail in the description that follows.

Regarding the relative position of the apertures/eyelets with respect to adjacent (proximal) eyelets, these eyelets are mounted into the “upstream” side, i.e., the entry of the apertures in the board, and thus a number of tows or yarns may be guided in the same direction during fiber processing. Those boards are also called “eye boards.”

As mentioned briefly above, deposits of so-called “fuzz” or “fluffs” of fibers tend to accumulate on these eye boards. This accumulation results in disruption of the fiber processing line. This accumulation of fiber on the eye boards that guide the fiber from spools on a creel is a problem in fiber processing and manufacture of fiber reinforced composites because when the accumulation of the fuzz is substantial, it moves with the fibers downstream towards the next steps in the composite manufacturing line. When the fiber tow/yarn which has the fuzz accumulation arrives at a location for downstream processing, the fiber in the tow/yarn bundle that is attached to the fuzz accumulation can break, and then the neighboring fiber can break as well.

is a photograph of the beginning stages of such fuzz or fluff accumulation on a bundle of filaments of fiber, e.g. tow, or yarn. As can be seen in the photograph, the fuzz comprises a number of individual broken fiber filaments as a result of the tow shredding at the contact points (usually the eyelets)

The typical fuzz accumulation deposit process on the eye board is as follows:

Step 1 is shown schematically in. Two bundles of fibers,, also called yarns, or tows, run in parallel, in the direction of the arrow, into separate apertures, which may be lined with eyelets,shown schematically in cross-section. These eyelets are mounted on the same surface, in this case a board, also referred to as an eye board. A single broken filamenthas broken from the yarn. Note that a first endof the filamentis free at this point, while the rest of filamentis still entrained within the bundle of fibers in the tow.

Step 2 is shown schematically in. As shown in, when the first endof the broken filamentgets close to the upstream side of an adjacent eyelet or aperturein the eye board, the broken filament endis pinched between the adjacent yarn or towwhich is moving through eyelet. As shown in, the arrow shows the direction in which the towsandare moving. The free endis thus entrained into the adjacent towand the rest of the single fiber, being entrained in the tow, is pulled along with the rest of the tow.

Step 3 is shown schematically in. Because the free endis pinched between eyeletand the tow, the other end of the fiberis pulled through eyeletby the rest of the tow. As shown in, the fibertherefore deposits in between the two eyeletsand. By repeating these Stepstoover and over, fiberswill build up between the two adjacent eyeletsand, thereby causing a large amount of fuzz to build up, which takes the form of a U or a bridge between the two eyelets, that is, adjacent apertures in the eye board surface. One can appreciate that the cycle of breakage tends to accelerate, since when more fibers are built up, the friction on the eyelet or the aperture increases, thereby causing more fibers to break as they are pulled across the broken fibers trapped in the eyelet or aperture.

is a photograph of an example of such U-shaped fuzz that has built up between two such adjacent apertures lined with eyelets in a surface of an eye board. In addition to the immediate problem of these fuzz deposits causing loss of fiber over time, when fuzz deposit size becomes too large the entire deposit will move with the tow or yarn and will badly impact the next step of the fiber processing operation. For instance, fuzz accumulates at eyelets, and it bridges between two holes. When fuzz accumulation gets big, it finally moves with the tow. When reaching a downstream slot plate, it cannot pass through and will start to shred the fiber, and then the neighboring one, and thus tows are lost.

Surprisingly, the inventors have determined that this phenomenon tends to disappear significantly if a distance between two apertures/eyelets that are proximal to each other is longer than the length of a broken single filament. Typically, this minimum distance is 1 inch or 2.5 cm for a typical carbon fiber such as P35 carbon fibers available from Zoltek Corporation. But in most of the cases the purpose of the eye board is to guide or gather the yarns more closely together, since they will be formed into shapes, or woven or other steps needed to from a composite, in downstream processing. Thus, the distance between yarn/tow in the eyelets in the apertures should be considerably smaller than 2.5 cm, e.g. smaller than 20 mm, or smaller than 19 mm, 18 mm, or smaller than 17 mm, or smaller than 16 mm, or smaller than 15 mm, or smaller than 14 mm, or smaller than 13 mm, or smaller than 12 mm, or smaller than 11 mm, or smaller than 10 mm, or smaller than 9 mm, or smaller than 8 mm, or smaller than 7 mm, or smaller than 6 mm, or smaller than 5, mm, or smaller than 4 mm, or smaller than 3 mm, or smaller than 2 mm, or even smaller than 1 mm.

This invention is thus directed in certain embodiments to a fiber guide that minimizes the fuzz or fluffs and the single fibers in the yarn that break and result in these fuzz/fluff deposits and accumulation. The inventors have determined that alternated offset inlet apertures of the eye board allow the fiber tows to be gathered more closely together, while at the same time minimizing the build-up of fuzz/fluff due to broken fibers.

An example of the relevant geometry is shown schematically in, which is a side cross-sectional view of a number of tows/yarnspassing through eyelets/aperturesin an eye board.shows a side cross-sectional view of exemplary offset pairs of eyelets/apertures mounted in an eye board. As can be seen in, which is an embodiment according to an aspect of the invention, the yarn/towsare guided through eyeletsand eyelets, which are offset from adjacent eyelets.

As shown in, the offset between eyelets/aperturesand eyelets/aperturescan be defined by the distances dand d. In order for the accumulation of fuzz/fluff due to fiber breakage to be minimized, the distance dbetween the inlets of the first aperturesand the second aperturesis larger than a distance d, which is measured transverse to the direction, shown by the arrow, in which the fibers tows/yarnspass. For avoidance of doubt, these distances dand dmay be considered to be measured from the upstream ends of the adjacent apertures where they guide the entering fibers. In the embodiment shown in, this is the location at which the passage opening of the aperture is smallest. Thus, the diameter of the apertures will not be a factor in measuring these distances.

Without being bound by theory, it may be that when one set of eyelets is offset from another, adjacent set of eyelets, the fuzz cannot deposit because the U shape or bridge is de-equilibrated, so not even the first broken filament end can deposit, and thus the cycle of acceleration of broken fibers never gets started.

shows a photograph of an exemplary such eye board that utilizes the offset eyelets in the apertures of the eye board surface that guides the tows of fibers. Example 1 (below) shows the results in terms of fuzz accumulation in grams/hour from the eye board shown in, compared to the amount of fuzz collected from the eye board shown in.

Exemplary Aspects of the invention are as follows:

Aspect 1: A fiber guide configured to guide fibers in a fiber processing system, the fiber guide comprising:

Aspect 2: The fiber guide of Aspect 1, further comprising a board defining the surface and a plurality of eyelets coupled to the board at positions corresponding to selected apertures, wherein the eyelets define the inlet of the selected apertures.

Aspect 3: The fiber guide of any of Aspects 1 and 2, wherein the inlet of the first aperture is offset from the surface of the board.

Aspect 4: The fiber guide of any of Aspects 1-3, wherein the distance dbetween the inlet of the first aperture and the inlet of the second aperture is 1 inch or larger and the distance dbetween the first aperture and the second aperture measured transverse to the direction in which the fibers can pass is less than 1 inch.

Aspect 5: A fiber processing system comprising:

Aspect 6: The fiber processing system of Aspect 5, the fiber guide further comprising a board defining the surface and a plurality of eyelets coupled to the board at positions corresponding to selected apertures, wherein the eyelets define the inlet of the selected apertures.

Aspect 7: A system for guiding fibers traveling along substantially parallel paths between an upstream location and a downstream location, the system comprising:

Aspect 8: A method for guiding fibers in a fiber processing system, the method comprising:

Aspect 9: The method of Aspect 8, further comprising passing fibers through apertures defined in a board and eyelets coupled to the board at positions corresponding to selected apertures, wherein the eyelets define the inlet of the selected apertures.

Aspect 10: A method for configuring a fiber guide to reduce fiber deposits in the fiber guide, the fiber guide having a surface defining a plurality of apertures through which the fibers can pass in a direction from an upstream side of the surface to a downstream side of the surface, the method comprising:

Aspect 11: The method of Aspect 10, further comprising coupling eyelets to a board at positions corresponding to selected apertures, wherein the eyelets define the inlet of the selected apertures.

Fiber was run through the eye board shown in(not having offset neighboring eyelets) for one hour. Fiber was then run through the eye board shown in(having offset neighboring eyelets) for one hour. When each line was stopped, the fuzz that accumulated on each type of board was weighed and compared. The process conditions and the results are shown in Tables 1 and 2, respectively.

As can be seen in Table 2, using the offset eyelets resulted in approximately three-fold reduction in the amount of fuzz accumulated on the eye board.

Next, an experiment similar to Example 1 was carried out, but the two eye boards (with and without adjacent eyelets) were used on two separate fiber lines for 18 days. The fuzz was collected every two hours and the average grams per hour for each day were calculated. These data are shown infor each date. Note that on January 5, the line using the eye boards having the offset eyelets went down for reasons unrelated to the fuzz accumulation on the eye boards. However, when the line was operating, the global trend for the offset eyelets was clearly lower fuzz accumulation than the non-offset eyelets. Over the course of the experiment (for days when both lines were running), approximately 73% less fuzz was accumulated on the line utilizing the offset eyelets. Note also that the amount of fuzz generated appeared to decrease over time for the offset eyelets, which may be attributable to a start up effect.

Regarding Examples 1 and 2, it is apparent that fuzz accumulation on the eye board is greatly reduced (−73%) by using offset eyelets.

Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.