Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1999-08-30
2001-06-05
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S388000, C250S50400H, C250S492100, C392S424000
Reexamination Certificate
active
06242717
ABSTRACT:
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.
REFERENCES:
patent: 4015340 (1977-04-01), Treleven
patent: 4591724 (1986-05-01), Fuse et al.
patent: 4710638 (1987-12-01), Wood
patent: 5294260 (1994-03-01), Larsen-Moss et al.
patent: 5726815 (1998-03-01), Gunter et al.
patent: 5861633 (1999-01-01), Mandellos
patent: 5973331 (1999-10-01), Stevens et al.
Lucent Technologies - Inc.
Pelham Joseph
Thomas Kayden Horstemeyer & Risley LLP
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