Abstract:
A spool for optical fiber ribbon or other flexible media has an opening communicating with an interior of the spool in which a first end of a helical guide is located. The helical guide receives the ribbon from an exterior winding space to direct the ribbon to an auxiliary winding surface located outside one of the main flanges at an end of the spool.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application is related to and claims priority from U.S. Provisional Application Ser. No. 60/331,900, filed Nov. 19, 2001, which is incorporated herein by reference in its entirety. 

   FIELD OF THE INVENTION 
   The invention relates to spools for storing and transporting lengths of fibers, ribbons, cables and other elongated flexible materials, especially optical fiber ribbons. 
   BACKGROUND OF THE INVENTION 
   It is well known to store and transport lengths of a flexible material wound onto a spool or reel. The spool typically consists of a cylindrical barrel with a flange at each end projecting radially outwards. Examples of prior spools for fiber optic media are described in U.S. Pat. No. 5,908,172 to Pierro et al., issued Jun. 1, 1999, which is incorporated herein by reference in its entirety. 
   When material is wound on a spool, the inside end portion tends to be close to the barrel and covered by material that is subsequently wound. For certain materials, however, such as for fiber-optic media, access to both ends of the wound material is desirable for integrity testing to ensure that the material is not damage or defective. The inside end portion, therefore, must be led away from the barrel of the spool to a more accessible position. 
   It is important to avoid damage to either the inside end portion or the main portion of the fiber-optic medium, and to avoid the formation of sharp bends or kinks that might be mistaken for faults when the medium is being tested. 
   SUMMARY OF THE INVENTION 
   According to one aspect, the invention provides a device for winding an elongated material. The winding device includes a barrel having an outer surface and defining a longitudinal axis and at least one flange secured to the barrel and having an outer surface. The outer surfaces of the barrel and the flange define an exterior space for winding an elongated material. One of the barrel and the flange defines an interior and an opening. The opening communicates with both the interior and the exterior space for passage of an end portion of the elongated material therebetween. 
   The winding device further includes a material guide having a first end located within the interior adjacent the opening and an opposite second end. The second end of the material guide located longitudinally outwardly from the flange opposite the exterior space. The material guide defines a pathway for passage of the end portion of the elongated material between the first and second ends, a portion of the pathway being helical. 
   In another aspect, the invention provides a spool including a barrel having a hollow cylindrical wall defining opposite inner and outer surfaces and a pair of flanges secured to the barrel to define a winding space between the flanges. The wall of the barrel includes an opening communicating with the winding space. The spool further includes an insert having an outer cylindrical surface slidingly received by the inner surface of the barrel wall. The barrel and the insert define a helical guide channel therebetween having opposite first and second ends. The first end of the helical guide channel is located adjacent the opening in the barrel wall. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation view of a spool according to the present invention; 
       FIG. 2  is an axial section view through the spool of  FIG. 1 ; 
       FIG. 3  is an isometric exploded view of a spool half and end insert of the spool of  FIG. 1 ; 
       FIG. 4  is an enlarged detail of  FIG. 2 ; 
       FIG. 5  is an enlarged detail section along the line  5 — 5  in  FIG. 1 ; 
       FIG. 6  is an end elevation view of a spool according to a second embodiment of the invention; 
       FIG. 7  is a side elevation view of one of the spool halves of the spool of  FIG. 6 ; 
       FIG. 8  is an end elevation view of a spool having an insert orienting construction, the spool shown with the insert removed; 
       FIG. 9  is an end elevation view of an insert adapted for receipt within an end of the spool of  FIG. 8 ; and 
       FIG. 10  is an axial section view through the insert of FIG.  9 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings, and initially to  FIGS. 1  to  5 , one embodiment of spool, indicated generally by the reference numeral  10 , includes two spool halves  12  and  14 , and two end inserts  16 . Each spool half  12 ,  14  includes a barrel  18 , a radially outwardly-extending main flange  20  at one end, an end wall  22  at an opposite end, and a hollow axial shaft  24 . 
   The end wall  22  of each spool half  12 ,  14  joins the axial shaft  24  to the barrel  18 . Radial ribs or the like may also be provided within a core region of the spool, between the axial shaft  24  and the barrel  18 , to provide increased strength and stiffness if desired. As illustrated, the end walls  22  are provided with fittings  26 ,  28  for quick-release fasteners  30  to join the two spool halves  12 ,  14  together. Suitable fittings and fasteners are described in more detail in U.S. Pat. No. 5,908,172. 
   As illustrated, each main flange  20  includes a frusto-conical wall  32  having a smooth face on one side directed into the central region of the spool  10  when the two halves  12 ,  14  are assembled. Radial stiffening ribs  34  are positioned on the outward side of the flange  20 . It should be noted, however, that other forms of flanges and spools may utilize the features of the present invention. For example, the spool may include radially straight flange walls or other stiffening structures than those particularly shown. When the two spool halves  12 ,  14  are assembled together, the barrels  18  and the smooth walls  32  of the main flanges  20  define an annular region onto which an optical fiber ribbon or other length of thin, flexible material can be wound. 
   A window  38  is provided through the barrel  18 , close to the main flange  20 . As may be best seen in  FIG. 5 , the side walls of the window  38  in the circumferential directions are formed with bevels  40 ,  42  on both faces. The bevels  40 ,  42  are angled and aligned so that an optical fiber ribbon  44  may pass from an alignment lying along the outside of the barrel  18  to an alignment lying along the inside of the barrel without any sharp kinks or bends. As may be seen in  FIG. 5 , the bevels  40 ,  42  are formed symmetrically on both sides of the window  38 , so that a ribbon  44  may enter the window either from left to right or from right to left as seen in FIG.  5 . The window  38  shown in  FIGS. 1 and 5  is dimensioned to receive a flat ribbon, which occupies most of the axial length of the window while lying fairly flat against the bevels  40  and  42 . It will be understood that a narrower ribbon could be passed through the window  38 , or that the shape of the window could be altered to fit different forms of media. 
   The inside of the barrel  18  is formed with two steps. A circular step or shoulder  46 , facing away from the end wall  22 , encircles the barrel between the window  38  and the end wall  22 , preferably fairly close to the window. When the spool  10  is assembled, the insert  16  fits within the barrel  18  and seats against the step  46 . 
   A helical step  48 , also facing away from the end wall  22 , forms a cusp immediately adjacent to the window  38 , on the side of the window towards the end wall, and extends from that cusp helically round the barrel in both directions and away from the end wall  22 . The ends  49  of the helical step  48  meet the axial end of the barrel  18  almost opposite the window  38 . The step  48  is shown in phantom lines in  FIG. 2  because, in the interests of clarity, only the parts of the helical step above the plane of section are shown at each end of the barrel  10 . 
   The insert  16  has at its outer end an auxiliary flange  50  which is spaced from the end of the barrel by a distance approximately equal to the axial height of the window  38  when the insert is inserted into the barrel  18  and seated against the shoulder  46 . An auxiliary barrel  51  is formed by the portion of the insert  16  between the end of the barrel  18  and the auxiliary flange  50 . 
   When the insert is  16  is received in the barrel  18  and seated on shoulder  46  such that the insert  16  is correctly oriented, the helical step  52  parallels the step  48  of the barrel  18 . This positions the cusp of the step  52  immediately adjacent to an end of the window  38  furthest from the end wall  22 . The parts of the insert  16  on either side of the step  52  are radiused to fit snugly within the parts of the barrel  18  on their respective sides of the helical step  48 . 
   As is shown in  FIG. 4 , a helical channel  54  is formed between the steps  48  and  52  of the barrel  18  and the insert  16 , respectively. The depth of the channel  54  in the radial direction of the spool  10  is set by the height of the steps  48  and  52 . The width of the channel in the axial direction of the spool is set by the spacing between the steps  48  and  52 , which is approximately equal to the axial length of window  38 . The step  52  is gradually reduced in height towards the auxiliary flange  50  such that there is not a substantial step across the area of the auxiliary barrel  51 . 
   In use, the two spool halves  12 ,  14  are assembled together. The inserts  16  are then inserted into the barrel  18 . The inside end of a fiber optic ribbon or other length of flexible media is brought to the outside of the barrel  18 , and fed through the window  38  into the channel  54 . The ribbon is then pushed further into the window  38  and along the channel  54 , until the end of the ribbon emerges into the auxiliary barrel area  51 . The ribbon  44  can then be both pushed and pulled until a sufficient length of the ribbon is at the auxiliary barrel area. The free end may then be wound round the auxiliary barrel, between the end of the main barrel  18  and the auxiliary flange  50 , and secured with tape, clips, or any other suitable expedient. The free end may be led off the auxiliary barrel  51  through a gap  56  in the auxiliary flange  50 , and taped to the end face of the spool. The spool  10 , with the inside end of the ribbon  44  effectively secured to the barrel surface where it emerges from the window  38 , may then be wound full of ribbon by conventional manual or automated spool winding. 
   When it is desired to test the ribbon  44 , the inside end can easily be freed from the auxiliary barrel  51 , and the outside end is exposed and accessible on the surface of the windings. The two ends can thus easily be connected to test equipment. Because of the arrangement of the window  38  and the helical guide channel  54 , there are no kinks or sharp bends in the ribbon that might stress the optical fiber or otherwise interfere with optical transmission along the fiber, and that might thus erroneously be detected as faults or flaws in the ribbon. 
   It will be seen that each of the spool halves  12 ,  14  and the inserts  16  may be made from a plastic material in a single operation using a two-piece mold parting in the axial direction. Only small, simple mold inserts are needed for the window  38 . The spool  10  is thus very economical to manufacture. It will be understood by those skilled in the art that, for reasons of practicality in molding, the cylindrical parts of the spool may in fact need to be slightly tapered. However, the necessary taper need not interfere with the function of the spool. 
     FIGS. 6 and 7  show a second embodiment of the invention. In  FIGS. 6 and 7  features that are the same as or equivalent to those shown in  FIGS. 1  to  5  are given reference numerals greater by  100  than those used in  FIGS. 1  to  5 . In the interests of simplicity, only one spool half  112  is shown in FIG.  7 . It will be understood that to form a complete spool two spool halves  112  are to be joined together with connectors that may be similar to the connectors  26 ,  28 ,  30  shown in FIG.  2 . 
   In the second embodiment, a spool half  112  does not include a separate insert, although such may be utilized if desired. Radial ribs  160  join an axial shaft  124  to the inside of a barrel  118  over the entire axial length of the barrel. The barrel  118  extends beyond a main flange  120  to form an auxiliary barrel surface  151 . Between two of the ribs  162 ,  164  is formed a cylindrical space  166 . A window  138  opens through the barrel  118  into the cylindrical space  166 . A gap  168  opens through the auxiliary barrel surface  151  into the cylindrical space. 
   A helical channel  154 , formed in the ribs  162 ,  164  leads round the cylindrical space  166  from the window  138  to the gap  168 . The helical channel  154  is not closed on the side towards the space  166 , but is formed as a wide, shallow groove in the surfaces of the ribs  162 ,  164 . This arrangement is believed to be satisfactory provided that the ribbon  44  or other medium being loaded onto the spool is sufficiently stiff and springy that it will press itself into the groove  154  by its natural tendency to straighten out. Alternatively, a cylindrical plug could be inserted into the space  166  to prevent the ribbon  44  from coming out of the groove  154 . 
   It will be appreciated that the spool half  112 , because of the groove  154 , cannot be molded with a simple two-part mold. However, the groove  154  can easily be formed by a collapsible mold insert. Indeed, if the groove  154  is a perfect cylindrical helix, the groove  154  could be formed by a rigid insert with a helical ridge to form the groove. The mold insert could then be removed by unscrewing it along the groove  154 . Thus, this form of spool is also simple and economical to manufacture. 
   Although the spool  10  shown in  FIGS. 1  to  5  has a guide channel  54  formed between steps in two components, and the a variant of the spool shown in  FIGS. 6 and 7  has been described with a guide channel formed between a grooved component and a plain cylindrical one, those approaches could, of course, be interchanged. 
   Referring to  FIGS. 8-10 , there is shown a spool half  212  and an insert  216  for a spool according to the invention having a construction that ensures that the insert  216  will be received by the spool half  212  in a particular orientation. Such orienting of the insert  216  is desirable, for example, in spools such as spool  10  of  FIGS. 1-5  where formation of the helical guide channel requires proper orientation of the insert  16  with respect to the spool half. As shown in  FIG. 8 , the barrel  218  of the spool half  212  includes a groove  270 . The groove  270  is adapted to receive a correspondingly formed projection  272  on an outer surface of the insert  216  when the insert is received by the spool half  212  in the proper orientation. When the orienting construction shown in  FIGS. 8-10  is incorporated into a spool such as spool  10  of  FIGS. 1-5 , the projection  272  would preferably be aligned with the gap  56  in the auxiliary flange  50 . Also, the groove  272  would preferably be aligned with the bevels  40  for window  38 . Such positioning of the projection  270  and groove  272  simplifies the mold design. 
   The embodiments have been described primarily with reference to optical fiber ribbon as the material to be wound onto the spools. It will be understood that the spools could be used for other materials. The material is preferably sufficiently smooth and stiff to permit it to be pushed along the guide channel  54  without jamming and sufficiently stiff to remain in the open guide channel  154 . The spool of the present invention is not usually called for unless access is needed to both ends of the material wound on the spool, and sharp bends or kinks in the material are to be avoided. If the material is not ribbon shaped, then appropriate adjustments should be made to the shapes of the window  38  and the guide channel  54  or  154 . 
   Although embodiments have been described as being assembled from two identical spool halves  12  and  14  or  112 , the spool could be formed in one piece, or assembled in some other way. If the spool is assembled from two spool halves, the two spool halves need not be identical. A guide channel  54  or  154  could be provided at only one end of the spool, or different forms of guide channel could be provided at the two ends. For most purposes, however, it is believed that an arrangement with identical guide channels at both ends, each capable of receiving a lead in end wrapped round the spool in either direction, is preferable. This arrangement may be less versatile than one with different guide channels and may be slightly more expensive than one with a guide channel at only one end. However, the arrangement will be usually be easier to use because an operator does not need to spend time identifying the end with the desired guide channel, or worrying about whether that guide channel is left- or right-handed.