Abstract:
A method and apparatus are provided for substantially containing dust generated along a fiber tow path extending from a creel to a compression roller in an automated fiber placement machine, by enclosing substantially all of the path of the fiber tows between the creel and the compression roller within a barrier that is substantially impermeable to dust. A dust collection apparatus may have a porous media and/or utilize an electrostatic charge for entrapping the dust.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application No. 60/973,340, filed Sep. 18, 2007, the entire teachings and disclosure of which are incorporated herein by reference thereto. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to automated fiber placement, and more particularly to containment and filtration of airborne dust and vapors produced during an automated fiber placement process. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the last twenty years, the automated fiber placement manufacturing process has undergone substantial growth, primarily due to improved design and manufacturing processes, as well as an increasing number of applications. The incorporation of fiber materials in sports equipment such as golf clubs, tennis rackets or snow skis has shown others how these materials might also be appropriate for automobile hoods and fenders, recreational marine vessels or, aircraft wings or bodies and aerospace applications. 
         [0004]    Regardless of composition, carbon fibers or carbon fiber materials, in particular, hold certain common negative aspects that accompany the handling or manufacturing activities involving carbon fiber materials. The three most common areas of concern in the handling of carbon fibers are dust inhalation, skin irritation, and the effects of fibers on electrical equipment. Some carbon fiber is composed of many extremely light, thin strands, containing mainly carbon embedded in an epoxy resin. Alternatively, some carbon fiber may composed of many extremely light, thin strands, containing mainly carbon without being embedded in an epoxy resin However, carbon fibers by their nature, are somewhat “flinty” and tend to give off small, free floating particulate “flakes,” while being incorporated into a manufactured product. These “flakes” are generally indiscernible to the naked eye; thus, they are commonly referred to as “dust”. 
         [0005]    When parts are produced with an automated fiber placement machine, multiple tows of carbon, fiber glass, etc., must travel over somewhat torturous path from a refrigerated creel to the compression roller of a fiber placement head. It is known that during such an automated fiber placement process, minute pieces of fiber and resin may come loose from the tows and form a “dust” of particles which may possibly cause irritation to the skin of a machine operator and may possibly be potentially harmful if inhaled by that operator, or others, in substantial quantities. Also, non-resin embedded flakes or dust may accumulate on internal mechanism or elements of the automated carbon fiber placement machine and become electrostatically charged after a time. Such polarization has been determined significantly contributory to static electrical arcing within components that ruin the component or temporarily suspend the machine&#39;s operation. 
         [0006]    In the utilization of an automated carbon fiber placement machine, an operator may come into direct physical contact with the pre-impregnated strands of carbon fiber material. More specifically, many manufacturing processes utilizing carbon fibers are accomplished through what is commonly known as “hand lay-up” process. This process involves the direct application of the carbon fiber material or “tows,” by an individual immediately adjacent to and directly manipulating or controlling the lay-up application of the carbon fiber tows onto a mold. The “dust” may also cause malfunction or operating problems with the fiber placement machine apparatus if it is allowed to accumulate around bearings or other moving parts. Generally, as a precautionary step, operators of such fiber placement apparatus may spend substantial amounts of non-productive or “down-time” cleaning various surfaces and components of the apparatus to offset the adverse effects of such dust accumulation. 
         [0007]    Additionally, the dust particles may in some cases, have an electrostatic charge, which may cause the particles to be drawn into unsealed electric motors and/or control electronics. A number of manufacturers of carbon fiber material acknowledge that completed carbon fibers are good conductors of electricity. Accordingly, it is desirable to provide a method and apparatus for containing and removing the dust particles generated during the fiber placement process. Another negative aspect of carbon fiber manufacture is the possibility of skin irritation resulting from contact with carbon fiber dust. 
         [0008]    Therefore, what is needed then is an improved methodology for the carbon fiber placement manufacturing process that removes or substantially reduces the presence of the carbon fiber dust during that process and thus, removes or substantially reduces the level of risk to those individuals in the immediate presence of the carbon material. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The invention provides a method and apparatus for substantially containing dust generated along a fiber tow path extending from a creel to a compression roller in an automated fiber placement machine, by enclosing substantially all of the path of the fiber tows between the creel and the compression roller within a barrier that is substantially impermeable to dust. 
         [0010]    A dust impermeable barrier or shroud, according to the invention, may define a dust retention plenum therewithin, with a method or apparatus, according to the invention, further including a dust collection apparatus operatively connected to the plenum within the dust impervious barrier. In some forms of the invention, the dust collection apparatus may include a filter having a porous media for entrapping the dust. In some forms of the invention, the dust collection apparatus may utilize an electrostatically charged filter for entrapping the non-resin embedded dust. The dust collection apparatus in some forms of the invention may include both a porous media and utilize an electrostatic charge for alternatively entrapping either non-resin embedded or resin embedded dust at the operator&#39;s discretion. 
         [0011]    In a method or apparatus according to the invention, the dust collection apparatus may include a fan or other means for producing an air flow from the plenum enclosed by the dust impervious barrier through an electrostatically charged filter, or single filter element, or multiplicity of filters, in proximity to the refrigerated creel assemblies and fiber tows being utilized with an automated fiber placement apparatus operating in conjunction with a rotatable mandrel, or stationary tool configuration. The plenum within the barrier member may include an air inlet in fluid communication with ambient air around the barrier, with the inlet being disposed adjacent the compression roller. In some forms of the invention, the collection apparatus is disposed adjacent to the creel. 
         [0012]    In some forms of a method, according to the invention, carbon fiber flakes or dust are evacuated from a carbon fiber placement machine tool head by providing a flow of air over a main roller and fiber placement delivery system of the fiber placement machine tool head, with an apparatus which includes: a refrigerated spool carrier attached to a positioner cradle that moves along at least two axes; a carbon fiber tow path and redirect apparatus position between the refrigerated spool carrier and the automated fiber placement head; an electrostatic dust removal device positioned immediately adjacent to the fiber tow path prior to the tows reaching the automated fiber placement head apparatus; with the fiber placement head apparatus having at least one free upper direction wheel, at least one motorized roller, at least one feed roller, and at least one mechanism for cutting or severing the carbon fiber tows according to an attendant computer software design instruction. 
         [0013]    A method or apparatus, according to the invention, may be utilized with an automated fiber placement apparatus operating in conjunction with a rotatable mandrel. The invention may also be practiced, in some forms, with a stationary tablet mold configuration. 
         [0014]    One advantage of this invention is to provide an improved method and apparatus for the application of carbon fiber tows in either an automated machine tool or hand lay-up process that substantially reduces if not completely removes the presence of the carbon fiber dust. 
         [0015]    Another advantage of this invention to provide this method and apparatus in a product configuration that may be incorporated into certain automated carbon fiber placement machine tools without limiting or restricting the range of the machine tool head motion. 
         [0016]    It is another advantage of this invention to provide this method and apparatus in a product configuration that may be incorporated into hand lay-up carbon fiber placement machine tools without limiting or restricting the range of the machine tool head motion or being unmanageable by the operator. 
         [0017]    Another advantage of this invention is to provide this method and apparatus in a product configuration that does not require extensive knowledge or maintenance in operation while simultaneously providing effective carbon fiber dust reduction or removal. 
         [0018]    Another advantage of this invention is to provide a method and apparatus in a product configuration that reduces the need for scheduled cleaning or maintenance to assure efficient operation, thus increasing the amount of operation time that may be dedicated toward performing profitable manufacturing operations. 
         [0019]    A further advantage of this invention is to provide this method and apparatus in a product configuration that does not retard or reduce the rate of speed or efficiency of the placement of the carbon fiber tows onto a mold. 
         [0020]    The collection and evacuation of carbon fiber dust through an atmospheric evacuation process may rely on the physical density of the carbon fiber dust while it is suspended in the immediate atmosphere. The collection of the carbon fiber dust through an electrostatic device may also, or alternatively, rely upon the electrical conductivity of the carbon fiber dust. 
         [0021]    Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
           [0023]      FIG. 1  is a perspective illustration of a first exemplary embodiment of an apparatus for automated fiber placement of a tool surface of a mandrel according to the invention; 
           [0024]      FIG. 2  is a perspective illustration of a first exemplary embodiment of a fiber placement machine tool head apparatus according to the invention; 
           [0025]      FIG. 3  is a perspective illustration of a first exemplary embodiment of a fiber placement machine tool apparatus on a horizontal ram bearing a self-contained atmospheric evacuation and removal system incorporating at least one or more porous media filters according to the invention; 
           [0026]      FIG. 4  is a perspective illustration of a first exemplary embodiment of a fiber placement machine tool apparatus on a horizontal ram bearing a self-contained atmospheric evacuation and removal system incorporating at least one or more porous media filters in relation to a stationary tablet mold application, according to the invention; 
           [0027]      FIG. 5  is a perspective illustration of a first exemplary embodiment of a fiber placement machine tool apparatus on a vertical ram bearing a self-contained atmospheric evacuation and removal system incorporating at least one or more porous media filters in relation to a stationary tablet mold application, according to the invention; and 
           [0028]      FIG. 6  is a perspective illustration of a first exemplary embodiment of a fiber placement machine tool apparatus on a horizontal ram bearing a self-contained atmospheric evacuation and removal system with the inclusion of an electrostatically charged filter apparatus preceding the porous media filter or filters according to the invention. 
       
    
    
       [0029]    While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0030]      FIG. 1  shows an exemplary embodiment of the invention in the form of the apparatus of a multi-axes carbon fiber placement machine incorporating a horizontal ram for the placement of carbon fiber tows on a reciprocating rotatable mandrel mold device. The apparatus as shown includes a large envelope positioner  1  immediately adjacent to the mandrel  2  carrying the part mold to be formed and mandrel headstock and tailstock  3  that rotate the mandrel  2  along a rotary axis. The apparatus includes a positioner cradle  5  that moves along both an X and/or Y axis independently or simultaneously and that holds the refrigerated spool (creel) carrier  7 , adjacent to the carbon fiber tow  6  path and the carbon fiber tow support redirect  6   b.  The carbon fiber tows  6  proceed to the automated fiber placement machine tool head  4  for application to the mold and form as designed. 
         [0031]    In a preferred embodiment, the automated fiber placement machine tool head  4  as shown in  FIG. 2 , allows the passage of the carbon fiber tows  6  toward the feed module  14  through the automated fiber placement machine tool head  4  as guided by the free upper directional wheel  19  and the motorized roller  15 . The feed roller  16  creates continuous feed tension as guided by the hinge  17  when rotating along the “A” directional path from its illustrated position to position  18  and in constant tension against the motorized roller  15 . Also in a preferred embodiment, the bobbin  20  exerts a correlative tension against any rewind or backward inertia resulting from the cutting action of the upper anvil  12  striking the stationary lower anvil  11  as defined by the lower anvil stroke limit  13  as designed within the cutting module  10 . The tows proceed to the main roller  9  for application against the mandrel  2  carrying the part to be formed. 
         [0032]      FIG. 3  displays, in a preferred embodiment, in a horizontal application in relation to a rotating mandrel  2  mold and the entire tow  6  progression from their refrigerated spool carrier  7  and mounting on their individual motorized bobbins  8  that create and maintain proper tow tension, following though the immediate tow support redirect  6   b  into the automated fiber placement head  4 , and encapsulated in the air enclosure  21 . This air enclosure  21  is attached to the refrigerated spool carrier  7  with openings  22 ,  23  just behind the automated fiber placement head  4 , yet proximate to the main roller  9 . In this embodiment, the openings  22  and  23  are by design limiting the area that allows the passage of air surrounding the entire automated fiber placement head  4  and is designed to enhance the pressure generated by the filtering system  25  incorporated into the air enclosure  21 . The movement of the carbon fiber flakes or dust from the tows  6  as they travel from their individual motorized bobbins  8  in the refrigerated spool carrier  7  is facilitated by the air enclosure outlet  24  that channels the air flow into at least the one porous media filter  26  or possibly multiple porous media filters placed in the filtering system  25 . The vacuum evacuation of the ambient flakes or dust contained within the air enclosure  21  and removed through the air enclosure outlet  24  is the result of the blower fan  27  operation which simultaneously pulls the carbon fiber flakes and dust into the porous media filter(s)  26  and exhausts the air through the air outlet  28  in the direction illustrated by arrow  29 . In one embodiment, the air flow induced by the blower fan  27  is not less than five cubic feet per minute. 
         [0033]      FIG. 4  in a preferred embodiment, in a horizontal application in relation to a stationary tablet mold, displays the entire tow  6  progression from their refrigerated spool carrier  7  and mounting on their individual motorized bobbins  8  that create and maintain proper tow tension, following though the immediate tow support redirect  6   b  into the automated fiber placement head  4 , encapsulated in the air enclosure  21 . This air enclosure  21  is attached to the refrigerated spool carrier  7  with openings  22 ,  23  just behind the automated fiber placement head  4 , yet proximate to the main roller  9 . In this embodiment the openings  22  and  23 , are by design limiting the area that allows the passage of air surrounding the entire automated fiber placement head  4  and is designed to enhance the pressure generated by the filtering system  25  incorporated into the air enclosure  21 . The movement of the carbon fiber flakes or dust from the tows  6  as they travel from their individual motorized bobbins  8  in the refrigerated spool carrier  7  is facilitated by the air enclosure outlet  24  that channels the air flow into at least the one porous media filter  26  or possibly multiple porous media filters placed in the filtering system  25 . The vacuum evacuation of the ambient flakes or dust contained within the air enclosure  21  and removed through the air enclosure outlet  24  is the result of the blower fan  27  operation which simultaneously pulls the carbon fiber flakes and dust into the porous media filter(s)  26  and exhausts the air through the air outlet  28  in the direction illustrated by arrow  29 . 
         [0034]      FIG. 5  in a preferred embodiment, in a vertical application, in relation to a concave mold mounted on a stationary tablet, displays the entire tow  6  progression from their refrigerated spool carrier  7  and mounting on their individual motorized bobbins  8  that create and maintain proper tow tension, following though the immediate tow support redirect  6   b  into the automated fiber placement head  4 , is encapsulated in the air enclosure  21 . This air enclosure  21  is attached to the refrigerated spool carrier  7  with openings  22 ,  23  just behind the automated fiber placement head  4 , yet proximate to the main roller  9 . In this embodiment, the openings  22  and  23 , are by design limiting the area that allows the passage of air surrounding the entire automated fiber placement head  4  and are designed to enhance the pressure generated by the filtering system  25  incorporated into the air enclosure  21 . The movement of the carbon fiber flakes or dust from the tows  6  as they travel from their individual motorized bobbins  8  in the refrigerated spool carrier  7  is facilitated by the air enclosure outlet  24  that channels the air flow into at least the one porous media filter  26  or possibly multiple porous media filters placed in the filtering system  25 . The vacuum evacuation of the ambient flakes or dust contained within the air enclosure  21  and removed through the air enclosure outlet  24  is the result of the blower fan  27  operation which simultaneously pulls the carbon fiber flakes and dust into the porous media filter(s)  26  and exhausts the air through the air outlet  28  in the direction illustrated by arrow  29 . 
         [0035]      FIG. 6  in a preferred embodiment, in a horizontal application in relation to a rotating mandrel  2  mold, displays the entire tow  6  progression from their refrigerated spool carrier  7  and mounting on their individual motorized bobbins  8  that create and maintain proper tow tension, following though the immediate tow support redirect  6   b  into the automated fiber placement head  4 , is encapsulated in the air enclosure  21 . This air enclosure  21  is attached to the refrigerated spool carrier  7  with openings  22 ,  23  just behind the automated fiber placement head  4 , yet proximate to the main roller  9 . In this embodiment, the openings  22  and  23 , are by design limiting the area that allows the passage of air surrounding the entire automated fiber placement head  4  and is designed to enhance the pressure generated by the filtering system  25  incorporated into the air enclosure  21 . The movement of the carbon fiber flakes or dust from the tows  6  as they travel from their individual motorized bobbins  8  in the refrigerated spool carrier  7  is facilitated by the air enclosure outlet  24  that channels the air flow into at least the one porous media filter  26  or possibly multiple porous media filters placed in the filtering system  25 . The removal of any ambient dust is aided by the electrostatic apparatus  30  while the vacuum evacuation of airborne dust contained within the air enclosure  21  and removed through the air enclosure outlet  24  is the result of the blower fan  27  operation which simultaneously pulls the carbon fiber flakes and dust into the porous media filter(s)  26  and exhausts the air through the air outlet  28  in the direction of arrow  29 . The inclusion of the electrostatic apparatus  30  is particularly beneficial when non-resin embedded fiber tows are utilized. In one embodiment, the electrostatic apparatus  30  is included and its use is user selectable, e.g., based on whether non-resin embedded fiber tows or resin embedded tows are being used. 
         [0036]    All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0037]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0038]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.