Abstract:
The present invention provides an apparatus for forming fiber strands comprising a fiber forming device, a gathering shoe device and a winder device, the improvement comprising a gathering shoe device which includes at least one gathering shoe having an annular groove for receiving the fibers from the fiber forming device, the gathering shoe having a generally circular cross section at the annular groove and a diameter at the annular groove ranging from about 2.54 to about 6.35 mm. Another aspect of the present invention is a gathering shoe comprising a rod member having a longitudinal axis; and a groove extending circumferentially about the rod member, wherein the rod member has a diameter at the groove in the range of about 2.54 to about 6.35 mm. Still, another aspect of the present invention is a method of forming fiber strands comprising the steps of attenuating fibers, gathering the fibers into at least one strand on a gathering shoe, and winding the strand, wherein the strand forming imparts a tension in the fibers, the improvement comprising the step of gathering the fibers on a gathering shoe having an annular groove for receiving the fibers, a generally circular cross section at the annular groove and a diameter at the annular groove ranging from about 2.54 to about 6.35 mm to reduce the strand tension.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The instant invention relates to a gathering shoe arrangement for a continuous glass fiber forming operation. 
     2. Technical Considerations and Prior Art 
     Glass fibers are commonly formed by attenuating molten glass through orifices in a bushing. The fibers are then drawn across an applicator, which coats at least a portion of the fiber surface with a sizing composition. The coated fibers are then gathered into one or more discrete strands by gathering shoes and wound on a winding machine into a forming package. As a result of the glass fibers being drawn across the gathering shoes to form the strands, and in particular the friction developed between the fibers and the gathering shoes as the fibers contact the shoe, tension is added to the fibers. This additional tension in the fibers can result in degradation of the glass fibers as well as increased fiber breakage during the fiber forming and winding operation. Conversely, if tension can be reduced, the quality of the glass fiber product will improve. 
     The following patents disclose modified gathering shoe configurations. 
     U.S. Pat. No. 3,999,970 discloses a gathering shoe configured to reduce the wear of the shoe. The gathering shoe is formed from porous material, such as graphite. A gaseous fluid is introduced into a central cavity within the shoe and forced through slots in the porous material to the surface of the shoe such that the glass fiber strands formed by the shoe ride on a gaseous fluid cushion. 
     U.S. Pat. No. 4,526,598 discloses a gathering shoe which reduces the wrapping of fibers and/or strands around the shoe. The gathering shoe has an annular groove about its periphery. The groove includes plurality of holes radiating from the groove surface inward toward the center of the shoe. 
     It would be advantageous to reduce the tension in the fibers so as to improve the quality of the glass fiber strands. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus for forming fiber strands comprising a fiber forming device, a gathering shoe device and a winder device, the improvement comprising a gathering shoe device which includes at least one gathering shoe having an annular groove for receiving the fibers from the fiber forming device, the gathering shoe having a generally circular cross section at the annular groove and a diameter at the annular groove ranging from about 2.54 to about 6.35 mm. 
     Another aspect of the present invention is an apparatus for forming fiber strands comprising a fiber forming device, a gathering shoe device and a winder device, the improvement comprising at least one gathering shoe having an annular groove for receiving the fibers from the fiber forming device, wherein the gathering shoe is sized such that there is a line of contact between the fibers within the annular groove and the gathering shoe ranges from about 0.0661 to about 1.661 mm. 
     Yet, another aspect of the present invention is a gathering shoe comprising a rod member having a longitudinal axis; and a groove extending circumferentially about the rod member, wherein the rod member has a diameter at the groove in the range of about 2.54 to about 6.35 mm. 
     Still, another aspect of the present invention is a method of forming fiber strands comprising the steps of attenuating fibers, gathering the fibers into at least one strand on a gathering shoe, and winding the strand, wherein the strand forming imparts a tension in the fibers, the improvement comprising the step of gathering the fibers on a gathering shoe having an annular groove for receiving the fibers, a generally circular cross section at the annular groove and a diameter at the annular groove ranging from about 2.54 to about 6.35 mm to reduce the strand tension. 
     Another aspect of the present invention is a method of forming fiber strands comprising the steps of attenuating fibers, gathering the fibers into at least one strand on a gathering shoe, and winding the strand, wherein the strand forming imparts a tension in the fibers, the improvement comprising the step of providing a line of contact between the fibers and the gathering shoe ranging from about 0.0661 to about 1.661 mm. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational view of a forming station of a typical glass fiber forming operation, with portions removed for clarity. 
     FIG. 2 is an elevational view of a glass fiber gathering device incorporating features of the present invention, with portions removed for clarity. 
     FIG. 3 is an expanded view taken along line  3 — 3  of FIG. 2, with portions removed for clarity. 
     FIG. 4 is a schematic view illustrating the fibers as they are formed into strands by the gathering shoe of the present invention. 
     FIG. 5 is an elevational view of an alternate embodiment of a gathering shoe arrangement incorporating features of the present invention, with portions removed for clarity. 
     FIG. 6 is a view taken along line  6 — 6  of FIG.  5 . 
     FIG. 7 is a cross-sectional view of an alternate embodiment of a gathering shoe incorporating features of the present invention. 
     FIG. 8 is a cross-sectional view of a prior art gathering shoe. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be discussed generally in the context of its use in the forming and winding of glass fibers. However, one skilled in the art should understand that the present invention is useful in the processing of other fibers as discussed below. 
     Referring to FIG. 1, a forming station  10  of a glass fiber forming operation includes a forming apparatus  12  having a strand supply device  14  for supplying at least one strand  16  to a winder  18 . As used herein the term “strand” means a plurality of continuous fibers  20 . Fibers  20  are supplied from a glass melting furnace or forehearth (not shown) containing a supply of a fiber forming molten glass  22  and having a metal bushing  24  attached to the bottom of the forehearth. The molten glass  22  is drawn through a plurality of nozzles  26  in the bushing  24  and attenuated by the winder  18  to form glass fibers  20 . Water sprays  28  can be used to spray water at the newly formed fibers  20  to cool them after being drawn from the bushing  24 . For clarity in the drawing, the ceramic materials, cooling tubes and fins surrounding the metal bushing have been omitted. Alternatively, the forming apparatus  12  can be, for example, a forming device for synthetic textile fibers or strands in which fibers are drawn from nozzles, such as but not limited to a spinneret, as is known to those skilled in the art. Typical forehearths and glass fiber forming arrangements are shown in K. L. Loewenstein,  The Manufacturing Technology of Glass Fibres , (Third Edition 1993) at pages 85-107 and pages 115 to 235, which is hereby incorporated by reference. 
     The glass fibers can be formed from any type of fiberizable glass composition known to those skilled in the art including those prepared from fiberizable glass compositions such as “E-glass”, “A-glass”, “C-glass”, “D-glass”, “R-glass”, “S-glass” and E-glass derivatives. As used herein “E-glass derivatives” means glass compositions which include minor amounts of fluoride and/or boron, and preferably are fluorine-free and/or boron-free. Furthermore, as used herein, “minor” means less than one weight percent fluorine and less than five weight percent boron. Preferred glass fibers are formed from E-glass and E-glass derivatives. Such compositions are well known to those skilled in the art. If additional information is needed, such glass compositions as well as fiberization methods are disclosed in Loewenstein at pages 30-44, 47-60, 115-122 and 126-135 and U.S. Pat. No. 4,542,106 (see column 2, line 67 through column 4, line 53) and U.S. Pat. No. 5,789,329 (column 2, line 65 through column 4, line 24), which are hereby incorporated by reference. 
     The glass fibers can have a nominal filament diameter ranging from about 5.0 to about 35.0 micrometers (corresponding to a filament designation of D through U and above). For further information regarding nominal filament diameters and designations of glass fibers, see Loewenstein at page 25, which is hereby incorporated by reference. 
     The present invention is also useful in forming fibers or strands of materials other than glass fibers (“non-glass fibers”). Suitable non-glass fibers which can be formed using in the present invention are discussed at length in the  Encyclopedia of Polymer Science and Technology , Vol. 6 (1967) at pages 505-712, and U.S. Ser. No. 08/828,212 (now U.S. Pat. No. 5,883,023) at page 15, line 21 through page 17, line 10, which are hereby incorporated by reference. 
     Typically, after the glass fibers  20  are drawn from the bushing  24 , they are contacted with an applicator  30  to apply a coating or sizing composition to the surfaces of the glass fibers  20  to protect the fiber surface from abrasion during processing. As used herein, the terms “size”, “sized” or “sizing” refer to the aqueous composition commonly applied to the fibers  20  immediately after formation. Typical sizing compositions can include as components, among other constituents, film-formers, lubricants, coupling agents, emulsifiers and water. Non-limiting examples of sizing compositions that can be used in the present invention are disclosed in assignee&#39;s U.S. Pat. No. 3,997,306 (see column 4, line 60 through column 7, line 57); U.S. Pat. No. 4,305,742 (see column 5, line 64 through column 8, line 65) and U.S. Pat. No. 4,927,869 (see column 9, line 20 through column 11, line 19), and U.S. Ser. No. 08/787,735 now U.S. Pat. No. 5,908,689 (see page 7, line 1 through page 12, line 13 and page 28, line 15 through page 39, line 10) and Ser. No. 08/984,4 now U.S. Pat. No. 5,883,021 (see page 10, line 1 through page 15, line 17), which are hereby incorporated by reference. Additional information and further non-limiting examples of suitable sizing compositions are set forth in Loewenstein at page 237-291, which is hereby incorporated by reference. 
     A gathering device  32  mounted at the forming station  10  in any convenient manner is used to gather selected groups of fibers  20  to form one or more strands  16 . The strands  16  typically have about 100 to about 15,000 fibers per strand, and preferably about 200 to about 7,000 fibers and are drawn through the gathering device  32  at speeds of about 2,500 to about 18,000 feet per minute (about 762 to about 5486 meters per minute). Although not limiting in the instant invention, the particular gathering device  32  shown in FIG. 2, forms four strands  16 , but it should be appreciated that fibers  20  may be divided into fewer or more strands, preferably 1 to about 20 strands, and more preferably 1 to about 16 strands. Strands  16  can also be formed from fibers drawn from a plurality of adjacent bushings. 
     The forming apparatus  12  also includes spiral  34  for traversing the strands  16  along the length of the axis of rotation  36  of a rotatable collet  38  of the winder  18  during winding of the strand  16  about the surface  40  of the collet  38  to produce a forming package. Sidewalls  42  are positioned to generally enclose the forming station  10  and isolate the bushing  24 , applicator  30 , gathering device  32 , strands  16  and fibers  20  from similar elements in adjacent forming stations. Sidewalls  42  also provide support for other devices that can be used at the forming station  10  in forming the strands  16 . 
     Turning to the gathering device  32 , the particular arrangement illustrated in FIG. 2 is commonly referred to as a four-way splitter, i.e. gathering device  32  uses a gathering shoe arrangement  44  that divides the fibers  20  into four distinct strands  16 . The gathering shoe arrangement  44  includes a plurality of gathering shoes  46  configured to bundle the fibers  20  and form individual strands  16 , will be discussed later in more detail. Although not limiting in the present invention, in the particular gathering device  32  illustrated in FIG. 3, the gathering shoe is a rod member having a generally circular cross section and include a circumferential groove  47  along shoe surface  51  to gather the fibers  20  to form strands  16 . Each gathering shoe  46  is fitted within a threaded lower guide  48  and secured thereto by a compression fitting  50  which presses a portion of the guide  48  against a portion of shoe surface  51  of the gathering shoe  46 . Each shoe  46  and guide  48  is received within a corresponding cavity  52  of a splitter block  54 . Although not limiting in the present invention, in the particular embodiment of the invention shown in FIG. 3, block  54  includes 2 housing sections that are joined in any convenient manner, e.g. screws or bolts. Although not required, each gathering shoe  46  can be rotated about its longitudinal axis  56  while it collects the fibers  20  and forms the individual strands  16 . This can be accomplished in any convenient manner well known to those skilled in the art using, such as but not limiting in the present invention, a timing belt or gear arrangement. More specifically, in the particular gathering device  32  shown in FIG. 3, each lower guide  48  also includes a shaft  58  that extends from the guide  48  into the block  54  where it is captured by a gear  60  and secured thereto in any convenient manner, for example set screws. The gears  60  are interconnected in any convenient manner and at least one of the gears is connected to a drive (not shown) which rotates the gathering shoes  46  at a desired rate. It should be appreciated that the gears can be arranged such that all of the gathering shoes  46  rotate in the same direction or selected shoes  46  can rotate in opposite directions. In addition, the shoes  46  can rotate in either direction relative to the direction that the fibers  20  pass over the shoes  46 . As an alternative, the gears  60  may be interconnected, for example, with a timing belt that rotates all of the shoes  46  in the same direction. Although not limited in the present invention, the gathering shoes  46  should be rotated at a rate of about 0.25 to about 15 RPMs, and preferably at a rate of about 1 to about 8 RPMs. 
     It should be appreciated that although shoe  46  as shown in FIGS. 2 and 3 is a generally rod-like member with a generally circular cross-section configuration, shoe  46  can have other configurations, e.g. rectangular or octagonal. However, it is preferred that the cross section of the shoe  46  at groove  47  remain generally circular and the shape of the shoe be such that allows the relative contact point between the fibers  20  and the shoe  46  to remain constant as the shoe is rotated. 
     Although not required, the particular embodiment of the gathering device  32  illustrated in FIG. 2 also includes a guide arrangement  62  which includes a plurality of guide shoes  64 . The shoes  64  are configured and positioned such that prior to fiber attenuation, they direct groups of fibers  20  into the appropriate gathering shoe  46  and during the fiber attenuation and forming operation, they have minimal contact with fibers  20 . Guide shoes  64  are mounted on the gathering device  32  in any convenient manner. Although not limiting in the present invention, in the particular embodiment illustrated in FIGS. 2 and 3, each guide shoe  64  is fitted within a threaded upper guide  66  and secured thereto by a compression fitting  68  which presses a portion of the guide  66  against the outer surface  70  of the guide shoe  64 . The guide  66  extends through a slot  72  in guide  74 , which in FIG. 3 is shown as an angle member, and fixed thereto by fitting  68 , with flange  76  of the guide  66  and fitting  68  capturing the flange  78  of the angle member guide  74  therebetween. The slot  72  generally extends along the length of the angle member guide  74  so as to allow each guide shoe  64  to be positioned as required along the gathering device  32 . In the particular guide shoe configuration shown in FIG. 3, each guide shoe  64  includes a groove  80  that helps retain the unattenuated fibers  20  within a corresponding gathering shoe  46  prior to fiber attenuation. 
     The guide shoe mounting arrangement  62  discussed above allows for easy positional adjustment of the shoes  64  during glass fiber production. More specifically, although fibers  20  are drawn along the groove  80  surface as they are initially grouped to form the strands  16  as discussed above, it is preferred that the guide shoes  64  have minimal, if any, contact with the fibers  20  as the fibers  20  are drawn from the bushing  24  and strand  16  is wrapped around collet  38  by winder  18  during the actual fiber forming operation. The above guide shoe mounting arrangement  62  provides quick and simple positional adjustment of shoes  64  so that the shoe  64  can be positioned at a location such that the fibers are maintained within the groove  80  prior to fiber attenuation but make minimal contact with the shoe  64  during fiber attenuation. 
     If required, the guide shoes  64  can be mounted within the gathering device in a manner that allows the shoes  64  to rotate during the fiber forming operation using, for example and without limiting the present invention, a mounting and rotating arrangement similar to those discussed earlier in connection with gathering shoes  46 . 
     Although not required, the guide shoe  64  may be made of the same material and be configured similarly to the gathering shoe  46 . 
     FIG. 4 illustrates the amount of contact between the fibers and the surface of groove  47  of gathering shoe  46  of the present invention at the base of the groove. The amount of contact is determined by the wrap angle φ and the effective diameter D of the gathering shoe  46 . As used herein, “effective diameter” means the diameter of the shoe at the point where the fibers  20  are bundled together to form a strand  16 . In the embodiment of the invention illustrated in FIGS. 2 and 3, effective diameter D is measured at the base of groove  47  as shown in FIG.  4 . As will be discussed, reducing the amount of contact between the fibers  20  and gathering shoe  46  reduces the tension in strands  16 . This in turn improves strand quality and reduces fiber breakage. In addition, the winding speed, i.e. the speed at which the strands  16  are wound onto collet  38 , may be increased to take advantage of the reduced strand tension. Referring to FIG. 4, the greater the approach angle α of the fibers  20  from the bushing  24  (not shown in FIG. 4) to the gathering shoe  46 , the greater the wrap angle φ. Similarly, the greater the delivery angle β from the gathering shoe  46  to the spiral  34  (not shown in FIG.  4 ), the greater the wrap angle φ. Referring to FIGS. 1 and 4, it is apparent that the relative position of the bushing  24 , gathering device  32 , spiral  34  and winder  18  effect the wrap angle φ. However, as will be appreciated, the present invention minimizes the impact of the relative positioning of these fiber forming components on the strand tension. More specifically, in the particular embodiment of the present invention illustrated in FIG. 3, the gathering shoe  46  is basically cylindrically shaped with a circumferential groove  47  which collects a selected number of fibers  20  and forms a strand  16 . The effective diameter D of the gathering shoe  46  at the groove  47  as illustrated in FIGS. 3 and 4 is preferably between about 0.1 to about 0.25 inches (about 2.54 to about 6.35 mm) and more preferably between about 0.12 to about 0.17 inches (about 3.05 to about 4.32 mm). It is expected that the wrap angle φ will vary from about 3° to about 30°, preferably between about 5° to about 25° depending on the relative positions of the bushing  24 , gathering device  32 , spiral  34  and winder  18 , as well as the number of fiber strands to be formed. For example, in a four-way splitter, it is expected that the wrap angle φ can vary between about 5° to about 15°; in a six-way splitter, it is expected that the wrap angle φ can vary between about 5° to about 19°; and in an eight-way splitter, it is expected that the wrap angle φ can vary between about 5° to about 22°. Based on an effective diameter D at groove  47  of shoe  46  of between about 0.1 to about 0.25 inches, the line of contact between strand  16  and gathering shoe  46  at the base of groove  47  (i.e. [φ/360]Dπ) will vary between about 0.00261 to about 0.0654 inches (about 0.0661 to about 1.661 mm), and preferably between 0.00436 to about 0.0545 inches (about 0.111 to about 1.384 mm). For a preferred effective diameter D of gathering shoe  46  between about 0.12 to about 0.17 inches, the line of contact will vary between about 0.00314 to about 0.0445 inches (about 0.0798 to about 1.130 mm), and preferably between about 0.00524 to about 0.0371 inches (about 0.133 to about 0.942 mm). 
     The gathering shoes  46  are made of a material that resists the abrasive action of the glass fibers  20  rubbing against the surface of groove  47  while at the same time not adversely effecting the properties of the glass fiber  20 , i.e. degrade the fiber surface and lead to reduced surface quality and potential filament breakage. In addition, because of the environment in which it is being used and potential for molten glass beads contacting the shoe  46 , the shoe material should also exhibit high temperature resistance. Depending on the material, it is may extruded and machined or molded to shape. Without limiting the present invention, the shoes  46  may be made from graphite, brass, ceramics, phenolic resins or high temperature and abrasion resistant polymers. One type of graphite that may be used is CMG grade graphite which is fine grain graphite available from Pure Carbon Company, St. Mary&#39;s, Pa. One type of polymer that may be used is TORLON® 4301 synthetic polymer available from Amoco Polymers, Inc., Alpharetta, Ga. 
     If required, based on the position of the collet relative to the gathering shoe, selected gathering shoes can be mounted at an angle relative to the remaining gathering shoes to better maintain the strand within the groove of that particular shoe. More specifically, referring to FIGS. 5 and 6, in this particular embodiment of the present invention, gathering device  132  includes a gathering shoe arrangement  144  having gathering shoes  146 A and  146 B which are positioned within block  154  in a manner such that they are angularly offset from remaining gathering shoes  146 C and  146 D. This arrangement allows the strands  116  (shown only in FIG. 6) collected by shoes  146 A and  146 B to be directed to a selected portion of the collet while ensuring that the strands remain within the gathering shoe grooves  147 . In addition, although not required, in the particular gathering shoe arrangement illustrated in FIG. 5, shoes  146 A and  146 B are oriented such that all four strands  116  are aligned along a common centerline  190  when positioned within the respective shoe grooves  147 . 
     In one particular embodiment of the invention, the shoe  46  as illustrated in FIG. 3 was formed from a 1 inch (25.4 millimeters) long by 0.5 inch (12.7 millimeters) diameter piece of TORLON® 4301 polymer. Section  82  of the gathering shoe  46  was reduced to a 0.375 inch (9.53 mm) diameter to allow for close spacing of the lower guides  48 . Head section  84  remained at a 0.5 inch (12.7 millimeters) diameter. Groove  47  was formed in shoe  46  such that the groove had a 0.0312 inch (0.794 mm) radius at its base and a 35 degree included angle. The effective diameter D of the shoe  46  at groove  47  was 0.165 inches (4.92 mm). 
     It should be appreciated that as the gathering shoe  46  is used in production, the fibers  20  will wear the groove surface, resulting in increased friction between the fibers  20  and the shoe surface and distortion of the original groove configuration. As a result, the shoe  46  must be periodically redressed to smooth and reshape the groove surface. Depending on the number and size of the glass fibers, type of glass fiber, the production rate, strand tension and the shoe material, it is expected that the gathering shoes  46  will last between about 24 to about 72 hours of production or longer before redress or replacement is needed. As the effective diameter D of the gathering shoe  46  gets smaller, care must be taken during redressing to prevent breakage of the shoe  46 , especially when the gathering shoe  46  is made of a nonmetallic material. It is expected that the gathering shoes  46  can be used and reused at least until the effective diameter D reaches about 0.120 inches (3.048 mm). With proper maintenance procedures, it is expected that the effective diameter D can be as small as about 0.10 inches (2.54 mm). 
     If desired, the gathering shoe  46  can be reinforced to prevent premature breakage and allow for further reduction in the effective diameter D of the shoe  46  at the groove  47 . For example, and without limiting the instant invention referring to FIG. 7, a gathering shoe  146  similar to gathering shoe  46  can be reinforced by providing a rigid member  100  within the shoe  146  along its longitudinal axis  156 , at least in the vicinity of groove  147 . In the particular embodiment of the invention illustrated in FIG. 7, a hole  196  was drilled the length of shoe  146  and a 0.071 inch (1.803 mm) diameter steel needle  100  was positioned within the hole. The needle  100  was secured within hole  196  by an epoxy adhesive (not shown). When providing a reinforcing member within the shoe  146 , additional care must be taken to ensure that repeated use and redressing of the shoe does not inadvertently expose the reinforcing member, which in turn can result in surface degradation of the fibers  20  as they pass over and rub against the shoe and possibly break. 
     Reinforced gathering shoes  146  as shown in FIG. 7 were tested at a forming station of a glass fiber forming operation to determine the reduction in strand tension. More specifically, the gathering shoe  146  was made from CMG grade graphite and measured 1 inch long by 0.375 inch diameter (25.4 mm by 9.53 mm). The effective diameter D at the base of groove  147  was 0.125 inches (3.18 mm). The fiber forming operation was producing D450 glass fibers using a conventional shoe  300  as shown in FIG.  8 . The shoe  300  was made from P5 grade graphite available from Pure Carbon Company and had an outer diameter D O  of 1 inch (25.4 mm) and a diameter D G  measured at the base of groove  302  of 0.625 inches (15.88 mm). The strand tension was measure beneath the shoe position corresponding to the leftmost shoe in FIG. 2 using a Rothchild Electronic Tensiometer, Model 400MMT. The strand had a wrap angle of about 15°. Next, a shoe  146  was positioned in close proximity to the conventional shoe  300  and subsequently moved by hand toward the fibers until the fibers were no longer contacting shoe  300  but rather were being collected by shoe  146 . The strand tension was measured again. It was found in this particular test that shoe  146  reduced the average strand tension by about 22 percent when compared to conventional gathering shoe  300 . As used herein, “average strand tension” means the average of the tension in each strand as measures just below the gathering shoe  46 . 
     A second test was conducted to measure and compare the average strand tension for the gathering shoe  146  as shown in FIG.  7  and discussed above and the conventional shoe  300  as shown in FIG.  8  and discussed above. The shoes were used on a four-way splitter to produce four forming packages of D450 glass fibers. The forming operation was first run using gathering shoes  300  and the strand tension was measured beneath each shoe using a Rothchild Electronic Tensiometer Model 400MMT. Shoes  300  were then replaced with shoes  146  and the strand tension was measured again. It was found in this particular test that shoes  146  reduced the average strand tension between about 10 to about 27 percent, depending on the wrap angle of the strand, which in turn depended, in part, on the particular position of the shoe  46 , when compared to the conventional gathering shoes  300 . 
     By reducing the average strand tension, the forming operation can be modified to increase yield. More specifically, the winding speed can be increased to a speed that raises the average strand tension from the lower tension level associated with the use of the gathering shoes  46 ,  146 , to the tension level typically associated with the use of conventional gathering shoe designs. The increased winding speed will result in a higher yield. As an alternative, the winding speed may be maintained at its original speed but because the average strand tension has been lowered, it is expected that there will be fewer fiber breaks and thus the quality of the fiber strand will be improved. 
     There are other advantages to using the gathering shoe of the present invention. For example, because the shoe imparts less tension in the strand, its overall contribution to the strand tension is less, resulting in more uniform and consistent strand tension. This in turn results in more consistent build of the forming packages on the winder. In addition, because the strands have a lower tension and the tension is more consistent, less sizing is lost as the glass fibers pass through the gathering shoe. This results in a more consistent fiber coating. 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications, which are within the spirit and scope of the invention, as defined by the appended claims.