Abstract:
A removable rack for supporting a reflector in an oven having a light source where the reflector focuses light emitted from the light source in a predetermined manner. The preferred removable rack is arranged and configured to support a mirror array therein where the entire rack can be removably fixed to the interior of the oven in which it will be used. The rack is preferably arranged and configured to releasably engage the mirror array therein. A method for replacing a reflector disposed in the internal portion of an oven having a light source comprising the steps of providing a removable support rack for releasably supporting the reflector removably fixed to an interior portion of an oven. A reflector can be replaced by removing a member, fixing the removable support rack to the interior portion of the oven and removing the removable support rack from the interior of the oven. The rack and the mirror arrays supported thereon can be removed from the oven collectively by disengaging fixing members fixing the rack to the oven interior. The mirrors can then be removed from the rack by disengaging a support portion of the rack, thereby releasing the mirrors.

Description:
FIELD OF THE INVENTION 
     This invention relates to curing ovens and, more particularly, to an ultraviolet curing oven for curing optical fiber coatings. 
     BACKGROUND OF THE INVENTION 
     Ultraviolet curing ovens are used to cure optical fiber coatings, inks, and fiber ribbon cables, as well as many other materials in modem manufacturing, such as in the electronics manufacturing industry. More specifically, curing of optical fiber coatings is highly important to the performance of the fibers in light wave communication systems. The successful implementation of a light wave communication system requires high quality light guide fibers having mechanical properties sufficient to withstand the stresses to which they are subjected. Each fiber must be capable of withstanding along its entire length a maximum stress level to which the fiber will be exposed during installation and service. The importance of fiber strength becomes apparent when one considers that a single fiber failure will result in the loss of several hundreds of communication circuits. 
     The failure of light guide fibers in tension is commonly associated with surface flaws which cause stress concentrations and lower the tensile strength below that of a fiber of pristine unflawed glass. The size of the flaw determines the level of stress concentration and, hence, the failure stress. Even micron-sized surface flaws cause stress concentrations which significantly reduce the tensile strength of the fibers. 
     Long lengths of light guide fibers have considerable potential strength, but the strength is realized only if the fiber is protected with a layer of a coating material such as, for example, a polymer, soon after it has been drawn from a preform. This coating serves to prevent airborne particles from impinging upon and adhering to the surface of the drawn fiber, which would weaken it or even affect its transmission properties. Also, the coating shields the fibers from surface abrasion, which could occur as a result of subsequent manufacturing processes and handling during installation. The coating also provides protection from corrosive environments and spaces or separates the fibers in cable structures. 
     Light guide fibers are usually coated during a wet-coating process which typically involves drawing the light guide fiber through a reservoir of a liquid polymer material and then curing the liquid polymer material to harden it by exposing it to curing radiation (e.g., ultraviolet light). Ultraviolet curing ovens are commonly used in this type of process. 
     Such ovens typically include at least one ultraviolet bulb and a plurality of elliptical or parabolic reflectors, such as mirrors. The mirrors focus light emitted from an ultraviolet bulb onto the product to be cured. Commonly known ultraviolet ovens implement mirror segments which are generally several inches wide, and may comprise either a glass or metal substrate. These mirror substrates include reflective coatings disposed thereon, wherein the reflective surfaces provide specular reflections. Typically, several of these mirror segments are mounted in the oven to create a mirror array. 
     In as much as the ultraviolet bulb in a curing oven generates a substantial amount of heat, the oven must be cooled during use to prevent damage to the internal components of the oven. It is typically economically undesirable to filter the cooling air in industrial settings, and failure to do so results in dust and other contaminants depositing on the reflective surfaces of the mirrors through time, thereby reducing the specular reflectivity of the mirrors. As a result of the reduced specular reflectivity, the mirrors do not properly focus the ultraviolet light emitted from the bulb onto the product to be cured, thus mirrors used in such ultraviolet ovens must be cleaned and/or replaced periodically. Since the oven is out of commission during such maintenance, it is desirable to have the ability to remove and replace the mirrors easily and quickly in ultraviolet ovens, thereby reducing down time. 
     The removal and/or replacement process in known ultraviolet ovens implementing an array of removable mirrors is a laborious, time consuming task. The mirrors are typically fixed to the interior of the oven with dozens of small machine screws, for example, each of which requires removal before the mirrors can be removed for cleaning. Likewise, each of the small sized screws needs to be fixed in position to fix the mirror within the oven. This arrangement for fixing mirrors in ultraviolet ovens results in extensive machine down time and requires a large number of labor hours to remove and/or replace the mirrors, therefore adding materials to production costs. 
     Thus, a heretofore unaddressed need exists in the industry to overcome the aforementioned deficiencies and inadequacies. 
     SUMMARY OF THE INVENTION 
     The present invention is a removable rack for supporting a reflector in an oven having a light source where the reflector focuses light emitted from the light source in a predetermined manner. The removable rack comprises first and second longitudinal support members in side-by-side spaced relationship, each of the distal support members having a channel therein for receiving a first portion of the reflector. The first and second longitudinal support members comprise first and second ends. First and second base support members are arranged in side-by-side spaced relationship, spaced from and substantially parallel to the longitudinal support members and having first and second ends. Each of the base support members is arranged and configured for receiving a second portion of the reflector. A first end plate is affixed to the distal support members and the base support members at their first ends. A second end plate is affixed to the distal support members and the base support members are their second ends. 
     First and second cradle feet can be included extending from the first and second end plates in a direction substantially opposite that of the extension of the supports from the first and second end plates, respectively. The first cradle foot and the second cradle foot are both arranged and configured to removably fix the removable rack to the oven so that it can be easily removed. 
     The present invention also involves a method for removing a reflector disposed in an internal portion of an oven having a light source. The method comprises the steps of providing a removable support rack for releasably supporting at least one reflector and preferably an array of reflectors. The removable support rack is releasably fixed to an interior portion of the oven, and the array of reflectors is replaced by removing the removable support rack from the interior portion of the oven. The array of reflectors are then removed from the rack by removing a portion of the rack. A reflector, or an array of reflectors, can be placed in the oven through reversal operation of the previous steps. 
     Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
     FIG. 1 is a perspective view of a typical ultraviolet curing oven in an open position, exposing the interior of the oven, in which a known prior art mirror rack is installed. 
     FIG. 2 is a perspective view of a removable support rack of the present invention. 
     FIG. 2A is a perspective view of an ultraviolet curing oven in an open position, exposing the interior of the oven, in which a removable support rack of the present invention is installed. 
     FIG. 3 is a close-up, cut-away, perspective view of the external support of the removable support rack in FIG. 2 taken along line A—A. 
     FIG. 4 is a close-up, cut-away, perspective view of the base support of the removable support rack in FIG. 2 taken along line B—B. 
     FIG. 5 is a full cross section view of the removable support rack of the present invention illustrated in FIG. 2 taken along line C—C. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to FIG. 1, illustrated is a typical ultraviolet curing oven  10  having a known mirror rack  12  installed therein. The ultraviolet curing oven  10  comprises two primary sections, a first section  14  and a second section  16 . The first section  14  comprises an ultraviolet bulb  18  surrounded by two mirror arrays  20 , where each array  20  preferably comprises mirrors  21  having a substantially arcuate concave profile. Each mirror array  20  is supported within the first section  14  of the ultraviolet curing oven  10  by a mirror rack  12  which is fixed therein. The mirror rack  12  comprises a plurality of mirror brackets  22  for holding each mirror array  20  in its desired position. It is preferable that the pair of mirror arrays  20  are supported by the support rack  12  such as to be disposed in a concave arrangement about the bulb  18  disposed therein. Similarly, the second section  16  of the ultraviolet curing oven  10  comprises a center tube  24  surrounded by a similar pair of mirror arrays  20  held in position by another standard mirror rack  12 . Similar to the mirror rack  12  fixed in the first section  14 , a plurality of mirror brackets  22  fix the mirrors  21 , comprising the mirror arrays  20 , in position. In use, the second section  16  of the oven  10  is hingedly closed upon the first section  14  such that the mirror arrays  20  disposed in the first section and the mirror arrays  20  disposed in the second section surround the bulb  18  and the center tube  24 . In this arrangement, the mirror arrays  20  focus the ultraviolet light emitted from the bulb  18  toward the center tube  24  inside which a product to be cured, such as an optical fiber, can be positioned. As such, an optical fiber (not shown) needing to be cured (such as a fiber having a wet coating applied thereon), can be passed through the center tube  24  while the mirror arrays  20  focus the ultraviolet light emitted from the bulb  18  thereon, thereby curing the fiber. In the course of regular maintenance, the mirror arrays  20  are periodically removed or replaced for the purposes of cleaning or adjustment. In the known configuration illustrated in FIG. 1, each mirror  21  is individually removed from the oven  10  while the oven  10  is in the open position, such as illustrated in FIG. 1, by loosening fixing members  26  disposed within the mirror brackets  22 , which hold each mirror  21  comprising the mirror arrays  20  in position. In a typical configuration, each fixing member  26  comprises a small sized machine screw which can be tedious to handle. As can be seen in FIG. 1, there are typically two fixing members  26  used to hold each individual mirror  21  comprising the mirror array  20  in the desired position. Since each mirror array  20  typically comprises a plurality of individual mirrors  21 , this arrangement can result in a relatively high number of fixing members  26  required to hold each mirror array  20  in position. As such, removal of the mirror array  20  for maintenance or any other purpose requires disassembly of the array  20  by disengaging each of the fixing members  24  from the mirror brackets  22 . The mirror arrays  20  can then be cleaned and repositioned or replaced with new mirror arrays  20  by positioning each individual mirror  21  that comprises a mirror array  20  in the mirror rack  12  and reaffixing each fixing member  26  to its respective brackets  22  to hold the mirrors  21  in place. It can be seen that replacement of a full set of mirror arrays  20  in a typical ultraviolet curing oven  10 , a total of four mirror arrays  20  in the above described arrangement, is time consuming and laborious. Although the ultraviolet curing oven is disclosed herein as accommodating an optical fiber to be cured, it should be noted that such ultraviolet curing ovens can be used in a variety of applications, each of which can benefit from the present invention. 
     Turning next to FIG. 2, illustrated is a preferred embodiment of a removable reflector rack of the present invention, referred to generally with the reference number  100 . FIG. 2 illustrates the removable reflector rack  100  oriented in a horizontal position, as opposed to the vertical orientation in which the rack  100  would typically be positioned in use in an ultraviolet oven  10 , such as the oven  10  illustrated in FIG.  1 . In other embodiments, the removable reflector rack  100  can be used to support a variety of members for a variety of environments where the advantages of the present invention, as described in detail hereinafter, may be utilized. However, for ease of description, the present invention will be described as a removable reflector rack for supporting mirrors in an ultraviolet curing oven. The removable reflector rack  100  comprises a pair of distal supports  110 , a pair of base supports  112 , a first end plate  114 , and a second end plate  116 , where the first end plate  114  and the second end plate  116  are disposed and fixed at opposing ends of the distal supports  110  and the base supports  112 . The distal supports  110  and the base supports  112  preferably comprise extruded aluminum, however, it should be noted that either or both of the supports  110 ,  112  can comprise any suitable material that is unaffected by ultraviolet radiation. Likewise, it is preferable that the first end plate  114  and the second end plate  116  comprise stamped-out aluminum, however, it should be further noted that either or both of the end plates  114 ,  116  also can comprise any suitable material. The first end plate  114  and second end plate  116  can be fixed to the ends of the supports  110 ,  112  by any suitable manner, such as, for example, by a bolt, a weld, a screw, or the like. 
     The first end plate  114  and the second end plate  116  preferably comprise a substantially U-shaped planar member having a distal portion  118  and a base portion  120 . The first end plate  114  is preferably disposed substantially parallel to the second end plate  116 , having the distal supports  110  extending therebetween such that a longitudinal axis thereof is substantially perpendicular to the orientation of the first end plate  114  and the second end plate  116 . It is preferable that the longitudinal supports  110  are arranged in a side-by-side spaced relationship and are fixed to the first end plate  114  and the second end plate  116  toward the distal portion  118  of each. Similarly, it is preferable that the base supports  112  are arranged in a side-by-side spaced relationship, spaced from and substantially parallel to the distal supports  110  and disposed between the first end plate  114  and the second end plate  116 . It is preferably that the base supports  112  are fixed toward the base portion  120  of each of the first and second end plates  114 ,  116 , such that a longitudinal axis extending through the base supports  112  is substantially parallel to the longitudinal axis extending through the distal supports  110 . 
     The preferred first end plate  114  and preferred second end plate  116  further comprise a cradle foot  122  extending therefrom toward the base portions  120  of the plates  114 ,  116  and in a direction opposing the extension of the distal supports  110  and the base supports  112  from the first end plate  114  and the second end plate  116 , respectively. A preferred cradle foot  122  comprises at least one fixing aperture  124  disposed therein for fixing the movable support rack  100  to an interior portion of an ultraviolet curing oven  10 . Although two fixing apertures  124  are illustrated in FIG. 2, it should be understood that the cradle foot  122  can comprise any number of fixing apertures  124  suitable for fixing the removable reflector rack  100  to the housing of an ultraviolet curing oven  200 . 
     Each of the distal supports  110  is arranged and configured to receive an edge of at least one mirror  125 , preferably being concave, while each of the base supports  112  is arranged and configured to support an opposing edge of the mirror  125 . As such, the removable rack  100  of the present invention preferably supports a pair of mirror arrays  126 . A preferred mirror  125  to be supported comprises a portion of a substantially elliptical or circular profile. It is preferable that the removable support rack  100  is arranged and configured to accommodate an ultraviolet bulb (not shown) within the structure of the removable rack  100  such that the preferred pair of mirror arrays  126  supported by the rack  100  are arranged around the bulb in a half circle, half ellipse or the like. The mirror arrays  126  supported by the removable rack  100  can be removed from an ultraviolet curing oven  10  in which they are disposed as one unit by removing the entire removable rack  100  from the interior of the oven  10 . The mirror arrays  126  can then in turn be removed from the removable support rack  100  for repositioning or cleaning, as will be discussed next. 
     FIG. 3 illustrates a cross-section of one of the pair of distal supports  110 , taken along the cross-section A—A in FIG.  2 . It should be noted that although one of the pair of supports  110  is illustrated and discussed herein, it is preferable that both of the supports  110  are configured substantially similarly. A preferred embodiment of the support  110  comprises a reflector retainer cap rail  130  and a cradle side rail  132 . It is preferable that the reflector retainer cap rail  130  comprises an elongated U-shaped member, while the preferred cradle side rail  132  comprises an elongated, substantially planar member. Preferably, a portion of the cradle side rail  132  is seated within a recessed portion  136  of the cap rail  130 . A plurality of fixing members  134  are preferably used to fix the cradle side rail  132  into place with respect to the cap rail  130 . Although three fixing members  134  are illustrated, it should be understood that any number of fixing members can be included that is sufficient to hold the cap rail  130  in position. However, it should further be noted that it is preferred that there be less than two fixing members  134  for each mirror  125 . The distal support  110  is arranged and configured such that an edge of the mirror  125  is seated within the recessed portion  136  of the cap rail  130  substantially adjacent the cradle side rail  132  seated therein. It is preferable that the recessed portion  136  is arranged and configured to receive the mirror  125  in a “free-floating” manner, such as to provide space for thermal expansion as the mirror  125 , as well as the rack  100  itself, encounters the ultraviolet radiation while the oven  10  is in use. As such, the edge of the mirror  125  engaged by the distal support  110  is substantially free upon removal of the fixing member  134  and detaching the cradle side rail  132  from the recessed support  136 . It is preferable that the distal support  110  engages a plurality of mirrors  128  comprising a mirror array  126 . As such, the removal of the cradle side rail  132 , which extends the length of the rack  100 , facilitates quick and easy removal of the entire mirror array  126 . Similarly, an entire mirror array  126  can be fixed into place in the removable support rack  100  upon attaching the reflector retainer cap rail  130  and fixing it into position with the fixing members  134 . 
     FIG. 4 illustrates a cross-section of one of the pair of base supports  112  taken along the line B—B in FIG.  2 . It should be noted that although one of the pair of base supports  112  is illustrated and discussed herein, it is preferable that both of the base supports  112  are substantially similar in configuration. It is preferred that the base support  112  comprises a reflector bottom support  140  being substantially elongated and extending from the first end plate  114  and the second end plate  116  and fixed thereto. The preferred reflector bottom support  140  comprises a receiving notch  142  disposed therein and positioned at a defined angle to accommodate the preferred curvature of the mirror  125  to be supported therein. Since the mirror  125  can be slid in and out of receiving notch  142  and is preferably not fixed therein by additional means. Since a portion of each mirror  125  readily received and released by the receiving notch  142  disposed in the base support  112 , easy removal and replacement of the mirror  125  is provided for by removal and replacement of the reflector retainer cap rail  130 . It should be further noted that it is preferable that the receiving notch  142  to accommodate the mirror  125  such that the mirror  125  is engaged thereby in a “free-floating” manner to allow for thermal expansion. 
     The present invention also provides a method for removal and replacement of arrays of reflectors, such as mirror arrays  126  used in an ultraviolet curing oven  10 . Referring back to FIG. 2, it can be seen that a preferred removable reflector rack  100  supports a pair of mirror arrays  126 . In the preferred method for removal of the mirror arrays  126  from an interior portion of an oven  10 , a removable reflector rack  100  of the present invention is provided and removably fixed to an interior portion of an ultraviolet curing oven  10 . Fixing members (not shown), comprising screws, bolts, clamps, or any suitable member fixing the rack  100  in the oven  10 , are disengaged and the entire rack  100  is removed from the interior of the oven  10 . To remove the mirror arrays  126  from the rack  100  itself, the reflector rail cap  130  is disengaged from the cradle side rail  132  upon disengaging fixing members  134  used to hold the reflector rail cap  130  thereon. An edge of each of the mirrors  125  making up the mirror array  126  can be disengaged from the notch  142  disposed in a portion of the base support  112  and the desired mirror  125 . The mirrors  125  can be cleaned and placed back into the rack  100  or new mirrors can be disposed therein. The present invention is also a method for disposing a mirror  125  or a plurality of mirrors  125 , comprising one or more mirror arrays  126 , in an ultraviolet curing oven  10 . While the removable reflector rack  100  is outside of the oven  10  in which it will be used, a preferred plurality of mirrors  125  can be disposed in the rack  100  substantially adjacent each other, comprising a mirror array  126 , first by sliding an edge of each mirror  125  into the receiving notch  142  of each base support  112 . The cap rails  30 , corresponding to each of the distal supports  110  can then be fixed in place to the cradle side rail  132 , thereby fixing the mirror arrays  120  into place. The two mirror arrays  126  can be fixed in the oven  10  by positioning and fixing the entire rack  100  in the oven  10 . The rack  100  can then by fixed to a portion of the oven  10  by engaging fixing members (not shown) at the fixing apertures  124  disposed in each cradle foot  122 . 
     It should be emphasized that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of the present invention.