Abstract:
A cutting apparatus to cut a tow includes a tow support, a first blade, and a tow support deflector. The tow support deflector is disposed in cooperative alignment with the first blade to exert a deflecting force upon the tow support. The deflecting force substantially preventing the first blade from striking the tow support.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and is a divisional of U.S. application Ser. No. 11/204,355 entitled TOW CUTTING DEVICE AND SYSTEM, filed on Aug. 16, 2005, the entire contents of which is expressly incorporated by reference in its entirety herein. 
    
    
     FIELD 
     The present disclosure generally relates to backing materials for sheet and roll stock. More particularly, the present disclosure pertains to an improved backing material for pre-impregnated ply material. 
     BACKGROUND 
     Composite items are typically constructed from layers of material that are laminated together. The categories of materials utilized to fabricate or ‘layup’ composite items includes, for example: fiber; fabric; tape; film; and foil. Within each of these categories, a multitude of diverse materials are utilized. For example, fibers utilized includes: glass; carbon; aramid; quartz; and the like. When these fibers are arranged as woven sheets and unidirectional ribbons, they are referred to as fabric and tape, respectively. 
     Fiber placement is a process used to construct or fabricate composite items. These composite items include relatively simple planar sheets or panels to relatively large complex structures. The composite items are generally built up from multiple layers or plies of composite materials that are pre-impregnated with uncured resin (“prepreg”). These plies are placed on a form by a head that is positioned by a positioning device such as a robotic arm or gantry. 
     Composite materials are typically supplied in rolls or spools in a variety of widths. Generally, more highly contoured composite items are fabricated from relatively narrower composite materials. Composite materials having a width of about ⅛ th  inch to about 1 inch are typically referred to as “tow” and often, several strands of tow are placed at once in order to lay down a wider strip or “course.” A head on a tow placement device arrays a group of prepreg tows into a continuous band and compacts them against the surface of the form or layup tool. At the end of each course, all of the tows are generally cut and then rethreaded to start the next course. In addition, individual tows are sometimes cut during placement of a course to reduce the overall width, or shape, of the course. A disadvantage of conventional cutter modules in tow placement devices is that the cutters often fail. Cutter failures typically stop production until corrective measures are taken. These stoppages decrease laydown rates and increase product costs. 
     Another disadvantage of conventional cutter modules is that resin from the prepreg tows may foul the blades and other components of the cutter module. This fouling contributes to cutter failures and typically requires cleaning procedures to be performed. These cleaning procedures generally require the tow placement device to be shut down and may require partial disassembly. Such procedures also decrease laydown rates and increase product costs. 
     Accordingly, it is desirable to provide an apparatus and system capable of overcoming the disadvantages described herein at least to some extent. 
     BRIEF SUMMARY 
     The foregoing needs are met, to a great extent, by the present disclosure, wherein in one respect a device and system is provided that in some embodiments improves the reliability of cutter modules in a tow placement device. 
     An embodiment of the present disclosure relates to a cutting apparatus to cut a tow. The cutting apparatus includes a tow support, first blade, and tow support deflector. The tow support supports the tow. The first blade cuts the tow. The tow support deflector is disposed in cooperative alignment with the first blade to exert a deflecting force upon the tow support. The deflecting force substantially prevents the first blade from striking the tow support. 
     Another embodiment of the present disclosure pertains to a tow placement system to fabricate a composite item with a tow. The system includes a tow placement head, positioning device, and cutting apparatus. The tow placement head applies the tow to a tool. The positioning device positions the tow placement head. The cutting apparatus cuts the tow. The cutting apparatus includes a tow support, first blade, and tow support deflector. The tow support supports the tow. The first blade cuts the tow. The tow support deflector is disposed in cooperative alignment with the first blade to exert a deflecting force upon the tow support. The deflecting force substantially prevents the first blade from striking the tow support. 
     Yet another embodiment of the present disclosure relates to an apparatus to cut tow. The apparatus includes a means for supporting the tow, means for cutting the tow, and means for deflecting the supporting means to substantially prevent the cutting means from striking the supporting means. 
     Yet another embodiment of the present disclosure pertains to a method of cutting a tow. In this method, the tow is supported on a support, the tow is cut with a blade, and the support is deflected to substantially prevent the blade from striking the support. 
     There has thus been outlined, rather broadly, certain embodiments of the disclosure in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the disclosure that will be described below and which will form the subject matter of the claims appended hereto. 
     In this respect, before explaining at least one embodiment of the disclosure in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosure is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
     As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present disclosure. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a laminating system according to an embodiment of the disclosure. 
         FIG. 2  is an exploded detailed view of the end effector suitable for use with the laminating system of  FIG. 1 . 
         FIG. 3  is a detailed view of a cut/rethread module suitable for use with the laminating system of  FIG. 1 . 
         FIG. 4A  is a cross sectional view taken through line A-A of  FIG. 3  of a cutter configuration in a tow dispensing mode according to the embodiment of  FIG. 1 . 
         FIG. 4B  is a cross sectional view taken through line A-A of  FIG. 3  of a cutter configuration in a tow cutting mode according to the embodiment of  FIG. 1 . 
         FIG. 4C  is a cross sectional view taken through line A-A of  FIG. 3  of a cutter configuration in a tow rethreading mode according to the embodiment of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. As shown in  FIG. 1 , a laminating system  10  suitable for use in an embodiment of the disclosure includes a tow placement head  12 , positioning device  14 , and form  16 . The tow placement head  12  is configured to place a predetermined width of a tow  18  on the form  16 . The tow  18  is typically stored on and dispensed from one or more spools  20 . A composite item  22  is fabricated by placing the tow  18  from the spools  20  onto the form  16  and then performing a curing procedure. The curing procedure is varied according the tow manufacturers&#39; specifications. For example, curing bismaleimide (BMI) resins typically includes subjecting a fabricated composite item to elevated heat and pressure. 
     The positioning device  14  includes any suitable device to position the tow placement head  12  or end effector relative to the form  16 . Suitable positioning devices include a robotic armature as illustrated in  FIG. 1 , gantry-type devices, and the like. In an embodiment of the disclosure, the positioning device  14  is a robotic armature or gantry-type positioning device configured to control three to ten or more axes of movement. However, it is to be understood that the specific number of axes may depend upon the particular operating condition and thus, the number of axes controlled is not critical to the disclosure. 
     The form  16  includes any suitable form, tool, or mandrel for placing the tow  18  upon. The tow  18  is placed upon the form  16  in a plurality of courses  24  to generate a layer or ply  26 . Generally, items such as the composite item  22  are fabricated from multiple plies  26 . Typically, the surface of the form  16 , the courses  24  and/or plies  26  are referred to as a substrate  28  upon which subsequent courses of the tow  18  are placed. As shown in  FIG. 1 , the form  16  is controlled to rotate about an axis. When controlled to rotate thusly, the form  16  is typically referred to as a mandrel. In other embodiments, the form  16  may be stationary or controlled to move in various axes. For example, the form  16  may be secured to a sliding table or X-Y table. In this regard, these and other embodiments in which the form  16  and/or the tow placement head  12  are controlled to move, one relative to the other, are within the scope of the disclosure. Additionally, the movement of the form  16  and the positioning device  14  both act to position the tow placement head  12  relative to the form  16 . Furthermore, the movement of the form  16  and the positioning device  14  is generally coordinated to such a degree that the devices operate essentially as a single unit and thus, for the purpose of this disclosure, modulation of the positioning device  14  and/or the form  16  will be referred to with respect to the positioning device  14 . Characteristics of the form  16 , such as size, shape, contour, and the like, are based upon design parameters of the item  22 . 
       FIG. 2  is an exploded detailed view of the tow placement head  12  suitable for use with the laminating system  10  of  FIG. 1 . As shown in  FIG. 2 , the tow placement head  12  includes a main frame structure (“frame”)  30  and a plurality of components disposed along a tow path  32 . The frame  30  is configured to provide support and connection points for the plurality of components disposed along the tow path  32 . The tow path  32  basically includes a path from the spools  20 , where the tow  18  is stored, to the form  16 , where the tow  18  is placed. The plurality of components disposed along the tow path  32  include a pair of tow alignment trays (“trays”)  40 , a pair of index and key lock frames (“index frames”)  42 , a pair of tow cutter/rethread modules  44 , servo drive feed (“drive”)  46 , and an application roller (“roller”)  48 . It is to be noted that while an example is provided in which several components are present in pairs, in various other embodiments, some or all of the components are present as single, paired, or multiple components and all such embodiments are within the scope of the disclosure. 
     The trays  40  facilitate alignment of the tow  18 . For example, each tray  40  includes one or more channels  50  that guide the tow  18  to the roller  48  via the drive  46  and the tow cutter/rethread modules  44 . The channels  50  include any suitable structure configured to retain the tow  18  in alignment. Suitable structures include, for example, channels, grooves, slots, combs, and the like. The channels  50  include a surface that is compatible for use with the tow  18 . For example, ultra high molecular weight plastic (“UHMW”) plastic is generally compatible with BMI and other resin systems. In some embodiments, all or most of the tray  40  is UHMW plastic. In other embodiments, the tray  40  includes a layer or coating of UHMW plastic. 
     The trays  40  optionally include indexing points  54 , drive windows  56  and  58 . If present, the indexing points  54  facilitate positioning the trays  40  upon the frame  30 . For example, as shown in  FIG. 2 , the indexing points  54  include notches configured to mate with respective tabs  60 . In another example, the indexing points  54  include bores or pins configured to mate with respective pins or bores. The drive windows  56  and  58  are optionally included to provide an opening for the drive  46  to contact the tow  18 . In other instances in which, for example, the drive  46  is disposed relatively above the channels  50 , the drive window  58  may be omitted. Depending upon the configuration of the tow cutter/rethread modules  44 , one or more cutter recesses are provided to facilitate proper operation of the tow cutter/rethread modules  44 . That is, if some portion of the tow cutter/rethread modules  44  operate below the surface of the tray  40 , the cutter recesses accommodate that the operation of the tow cutter/rethread modules  44 . In other instances in which the tow cutter/rethread modules  44  do not operate below the surface of the tray  40 , the cutter recesses may be omitted. 
     The index frames  42  facilitate securing respective ones of the trays  40  to the frame  30 . For example, the index frames  42  include one or more fasteners  62 . 
     The tow cutter/rethread modules  44  are described in greater detail herein. In general, the tow cutter/rethread modules  44  cut, clamp, and/or rethread the tow  18 . The tow cutter/rethread modules  44  include one or more fasteners  70  to secure the tow cutter/rethread modules  44  to the frame  30  and/or to secure the tow cutter/rethread modules  44  to intervening components. 
     The drive  46  is configured to engage the tow  18  and urge the tow  18  along the tow path. In this regard, the drive  46  includes one or more servo driven rollers  78 . In addition, the drive  46  includes a fastener  80  to secure the drive  46  to the frame  30 . 
     The roller  48  provides a bearing surface to urge the tow  18  toward the form  16  and thereby apply the tow  18  upon the substrate  28 . 
     In addition, the plurality of components disposed along the tow path  32  are configured to function in a coordinated fashion to handle a predetermined width of the tow  18 . According to design parameters of the composite item  22 , this predetermined width includes ⅛ th  inch, ¼ inch, ½ inch, 1 inch, and the like. Similarly, components configured to handle other width of the tow  18  are within the scope of various embodiments of the disclosure. 
       FIG. 3  is a detailed view of a cut/rethread module  44  suitable for use with the laminating system  10  of  FIG. 1 . As shown in  FIG. 3  the cut/rethread module  44  includes a plurality of channels  92 , rollers  94 , cut/clamp frames  96 , and blades  98 . In operation, each of the plurality of strips of the tow  18  is threaded along their respective channel  92 , past the roller  94 , and through the cut/clamp frame  96 . The channel  92  facilitates alignment of the tow  18 . The roller  94 , in various embodiments is free rolling, rolls in one direction only, and/or is controlled to roll via a servo or other such actuator. Each of the cut/clamp frames  96  includes an actuator, as shown and described herein, to urge a respective blade  98  toward the tow cutter/rethread module  44  and thereby cuts the respective tow  18  as the blade  98  passes through the tow  18 . The blade  98  includes any suitably hard and wear-resistant material. Suitable materials include metals such as carbide, steel and various alloys of steel, and non-metals such as ceramics and the like. 
     To rethread, the cut/clamp frame  96  is returned to the extended position and roller  94  and/or the drive  46  is controlled to advance the tow  18 . In this manner, some or all of the tows  18  are cut and rethread, in a controlled fashion, according to design parameters of the composite item  22 . 
     It is to be noted that while  FIG. 3  illustrates a cut/rethread module  44  configured to operate with  6  or fewer strips of the tow  18 , in various embodiments, the cut/rethread module  44  is configured to operate with any suitable number of the tows  18 . Suitable numbers of tow include 1, 2, 3, 4, 6, 12, and the like. 
       FIGS. 4A-4C  are cross sectional views taken through line A-A of  FIG. 3  of a cutter configuration in various modes according to the embodiment of  FIG. 1 . As shown in  FIGS. 4A-4C , in addition to the blade  98 , the cut/rethread module  44  optionally includes a blade  100  in co-operative alignment with the blade  98  and configured to assist or facilitate the cutting action of the blade  98 . If present, the blade  100  includes a suitably hard and wear-resistant material. Suitable materials include metals such as carbide, steel and various alloys of steel, and non-metals such as ceramics and the like. The cut/rethread module  44  further includes a tow support  102 , tow support deflector  104 , and actuator  106 . The tow support  102  includes a sprung support surface configured to support the tow  18 . The tow support  102  is configured to deflect in response to a force being exerted upon it. Suitable materials for the tow support  102  include spring steel, other resilient metals, plastics, and the like. Optionally, any surfaces of the tow support  102  coming in contact with the tow  18  are configured to reduce buildup of resin. For example, the tow support  102  is polished, chilled, and/or coated with a substantially non-stick material. Suitable non-stick materials include UHMW plastic and the like. The actuator  106  is operable to modulate the position of the cut/clamp frame  96  in response to signals from a controller. In particular, the actuator  106  is operable to draw the cut/clamp frame  96  relatively inwardly and return the cut/clamp frame  96  to an outward position. 
     As shown in  FIG. 4A , the cut/rethread module  44  is in a tow dispensing mode. That is, the cut/clamp frame  96  is extended relatively outwardly from the cut/rethread module  44 . As such, the tow  18  is free to move in a direction  108 . 
       FIG. 4B  is a cross sectional view A-A of a cutter configuration in a tow cutting mode according to the embodiment of  FIG. 1 . As shown in  FIG. 4B , the tow support  102  includes a fastening arm  110  and a support arm  112  that are joined at an intersection  114 . In various embodiments, the support arm  112  is flexible or essentially ridged and the intersection  114  is substantially ridged, flexible, or hinged. During the tow cutting procedure, the cut/clamp frame  96  is drawn in a direction  116  and relatively towards the cut/rethread module  44  via the action of the actuator  106 . Of note, the tow support deflector  104  is shown to exert a deflecting force upon the tow support  102  and causes the support arm  112  to flex or otherwise move in a direction as the deflecting force is translated through the tow  18 . The tow support deflector  104  includes a bearing surface disposed at or about at the level of the blade  98 . That is, the tow support deflector  104  is disposed slightly above, at, or slightly below the blade  98 . In a particular embodiment, when drawn towards the cut/rethread module  44 , the tow support deflector  104  contacts the tow  18  at or just prior to contact by the blade  98 . Generally, the tow support deflector is configured to provide a force to urge the tow support arm  112  away from the blade  98 . In this manner, the tow support deflector  104  substantially prevents the blade  98  from contacting the tow support arm  112 . Optionally, the tow support deflector  104  operates in conjunction with the tow support arm  112  to generate a clamping force upon the tow  18  as described herein. 
     As the blade  98  is drawn into the tow  18 , any movement of the tow  18  in the direction  108  urges the blade  98  in the direction  108 . This urging of the blade in the direction  108  generally acts to bring the blade  98  toward the blade  100 . It is an advantage of embodiments of the disclosure that as the blade  98  passes by the blade  100 , the close proximity of the blade  98  to the blade  100  and the urging of the two blades  98  and  100  together provides an efficient shearing action that improves cutting and/or reduces buildup of resin on the blades  98  and  100 . Upon completion of the cutting procedure, a portion of the tow  18  that is downstream of the blade  98  is free to continue moving in direction  108  while a portion of the tow  18  that is upstream of the tow  18  is essentially stopped until rethreading procedures are initiated. 
     The tow  18  is typically pulled or towed from the spool  20  and through the tow path  32  via the adhesion of the tow  18  to the substrate  28  combined with the movement of the tow placement head  12  relative to the form  16 . Therefore, when the downstream portion of the tow  18  is severed from the upstream portion of the tow  18 , the upstream portion of the tow  18  is controlled to stop via the action of a tow break and/or tends to stop of its own accord. In an embodiment, the tow support deflector  104  is configured to directly urge the tow support  102 . In this embodiment, essentially no clamping force is exerted upon the tow  18  via the action of the tow support deflector  104  urging the tow support  102 . For example, the tow support deflector  104  and the tow support  102  may be wider than the tow  18 . In this example, the edges of the tow support deflector  104  and the tow support  102  may directly contact one another. More specifically, one or both of the tow support deflector  104  and the tow support  102  may include a protruding portion that facilitates direct contact between the tow support deflector  104  and the tow support  102  without exerting a force upon the tow  18 . In another embodiment, the force exerted by the tow support deflector  104  further provides a clamping action upon the tow  18  disposed between the tow support deflector  104  and the tow support  102 . That is, the tow support deflector  104  urges the tow  18  into the tow support  102  and thereby deflects the tow support  102 . This clamping action facilitates retention of the tow  18  within the respective channel  92  as shown in  FIG. 3 . 
       FIG. 4C  is a cross sectional view A-A of a cutter configuration in a tow rethreading mode according to the embodiment of  FIG. 1 . As shown in  FIG. 4C , the cut/clamp frame  96  has been returned to the tow dispensing mode position as described in  FIG. 4A . In response to an absence of deflective forces exerted by the tow support deflector  104 , the support arm  112  has returned to a tow dispensing position. That is, the support arm  112  has returned to a level essentially in line with or very slightly above the blade  100 . As such, in response to being urged forward by the drive  46 , the cut end of the tow  18  is disposed to progress over the blade  100  substantially without catching thereupon. It is an advantage of various embodiments that the tow support deflector  104 , being level with or just below the level of the blade  98  inhibits contact of the blade  98  by the tow  18  during rethreading and dispensing modes. In addition, the tow deflector  104  further facilitates rethreading by inhibiting an upward movement of the tow  18  that could result in a rethreading error. 
     Optionally, the cut/clamp frame  96  includes a lifting pin  120  that traverses the cut/clamp frame  96  and provides a force to urge the support arm  112  into the tow rethreading and dispensing position. 
     The many features and advantages of the disclosure are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the disclosure that fall within the true spirit and scope of the disclosure. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the disclosure.