Patent Publication Number: US-2018030560-A1

Title: Article processing fixture

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/892,871, filed Oct. 18, 2013, which is incorporated in its entirety herein by reference. 
    
    
     TECHNICAL FIELD 
     This application relates generally to a fixture and, more specifically, to a fixture for supporting articles in an industrial process. 
     BACKGROUND 
     In industrial processes such as, for example, heat treating processes (e.g., hardening, annealing, stress relieving, normalizing, solution annealing, aging, quenching, tempering, cryogenic treating, sintering, etc.), surface treating processes (e.g., coating, plating, carburizing, decarburizing, case hardening, nitriding, oxidizing, diffusion hardening, etc.), and joining processes (e.g., brazing, diffusion bonding, and soldering, etc.), articles can be placed on or within fixtures in controlled temperature and chemical environmental enclosures such as, for example, furnaces, ovens, cryogenic baths, molten metal baths, fluidized bed reactors, quench baths, molten salt baths, pickling tanks, passivation tanks, and others. Fixtures that are resistant to elevated temperatures, and highly corrosive atmospheres and environments, and have high mechanical strength, high thermal fatigue strength, and other durability factors can be used to contain, support, and transport the articles throughout the various processs(es). 
     SUMMARY 
     The following presents a simplified summary of the disclosure in order to provide a basic understanding of some example aspects described in the detailed description. 
     In one embodiment, a fixture for supporting articles in an industrial process comprises a plurality of first elongate members extending longitudinally in a first direction. The plurality of first elongate members each comprise a rod member having a riveted portion at an end thereof. The fixture further comprises a plurality of second elongate members extending longitudinally in a second direction that is substantially perpendicular to the first direction and a plurality of third elongate members extending longitudinally in a third direction that is substantially perpendicular to the first direction and the second direction. The rod member of one of the first elongate members extends through an aperture of one of the second elongate members and an aperture of one of the third elongate members and is movably coupled thereto by its riveted portion. 
     In one example of the embodiment, the plurality of elongate members are movably coupled together to form a support platform for supporting articles that extends along a support plane. 
     In another example of the embodiment, each of the plurality of second and third elongate members comprises a flat stock member having a first connecting portion with a first aperture extending therethrough, a second connecting portion with a second aperture extending therethrough, and an intermediate portion joining the first connecting portion and the second connecting portion. 
     In yet another example of the embodiment, the flat stock member is non-bent and comprises a substantially flat first major surface, a substantially flat second major surface, and a thickness between the first and second major surfaces. In one example, the substantially flat first major surface extends perpendicular to the support plane. 
     In still yet another example of the embodiment, the first connecting portion comprises a first width, the second connecting portion comprises a second width, and the intermediate portion comprises an intermediate width that is less than both the first width and the second width. In one example, flat stock members for all of the second elongate members are identical to each other and flat stock members for all of the third elongate members are identical to each other. 
     In another example of the embodiment, the first portion comprises an edge portion that partially circumscribes an axis of the first aperture and maintains a substantially constant thickness of material partially about the aperture in a radial direction. 
     In yet another example of the embodiment, flat stock members for all of the second elongate members are substantially identical to each other and flat stock members for all of the third elongate members are substantially identical to each other. 
     In still yet another example of the embodiment, one of the first elongate members comprises a spacer that the rod member of the first elongate member is inserted through. The spacer defines a minimum or maximum distance between one of the plurality of second and third elongate members and another one of the plurality of second and third elongate members. 
     In another example of the embodiment, all of the plurality of elongate members are movably coupled to each other without welding that forms a load-bearing joint between the plurality of elongate members. 
     In yet another example of the embodiment, one of the plurality of elongate members comprises a first material and another one of the plurality of elongate members that is coupled thereto comprises a second material that is different from the first material. In one example, the first material comprises carbon and the second material comprises nickel alloy. 
     In still yet another example of the embodiment, the fixture further comprises at least one handle member movably coupled to the plurality of elongated members. In one example, the handle member comprises a first material and one of the plurality of elongate members that is coupled thereto comprises a second material that is different from the first material. In another example, the first material is lower in thermal strength than the second material. In still another example, the first material comprises carbon and the second material comprises nickel alloy. 
     In another example of the embodiment, the fixture further comprises a first stacking member comprising a first stacking portion and a second stacking member comprising a second stacking portion. In one example, the first and second stacking members are arranged such that when the fixture is stacked with an identical fixture with their first and second stacking portions aligned, the first stacking portion of the fixture will mate with the second stacking portion of the identical fixture. In another example, the first stacking portion of the fixture comprises a recess and the second stacking portion of the fixture comprises a projection that is receivable within the recess. 
     The embodiment described above may be provided alone or in combination with any one or more of the examples of the embodiment discussed above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention are better understood when the following detailed description is read with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an example fixture; 
         FIG. 2  is an exploded view of a first elongate member of the fixture; 
         FIG. 3  is a perspective view of an example flat stock member of the fixture; 
         FIG. 4  is a perspective view of another example flat stock member of the fixture; 
         FIG. 5  is a perspective view of yet another example flat stock member of the fixture; 
         FIG. 6  is a perspective view of still yet another example flat stock member of the fixture; 
         FIG. 7  is a cross-sectional view of the example fixture taken along plane  7  in  FIG. 1 ; 
         FIG. 8  is a cross-sectional view of another embodiment of the example fixture; and 
         FIG. 9  is a side view of yet another embodiment of the example fixture and an identical fixture. 
     
    
    
     DETAILED DESCRIPTION 
     Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. Relative language used herein is best understood with reference to the drawings, in which like numerals are used to identify like or similar items. Further, in the drawings, certain features may be shown in somewhat schematic form. 
     It is to be noted that the phrases “at least one of” and “one or more of”, as used herein, followed by a plurality of members herein means one of the members, or a combination of more than one of the members. For example, the phrase “at least one of a first widget and a second widget” means in the present application: the first widget, the second widget, or the first widget and the second widget. Likewise, “at least one of a first widget, a second widget and a third widget” means in the present application: the first widget, the second widget, the third widget, the first widget and the second widget, the first widget and the third widget, the second widget and the third widget, or the first widget and the second widget and the third widget. 
     It is further to be noted that the phrases “substantially parallel” and “substantially perpendicular” as used herein respectively mean within 15 degrees or less of parallel and perpendicular, and more preferably, within 10 degrees or less of parallel and perpendicular. 
     It is still further to be noted that the phrase “substantially identical” as used herein when describing two or more features means that the features are manufactured to be identical but may have slight differences in composition, size, or shape due to manufacturing tolerances. 
     Examples will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. Also, references numerals in the 100&#39;s refer to structure that corresponds to structure referred to by reference numerals having the same last two numbers. For example, reference numeral “125” refers to structure that corresponds to the structure referred to by reference numeral “25”. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. 
     A fixture  10  for supporting, containing, and transferring articles in an industrial process is shown in  FIG. 1 . More specifically, the fixture  10  may be used for supporting, containing, and transferring articles in industrial processes such as, for example, heat treating processes (e.g., hardening, annealing, stress relieving, normalizing, solution annealing, aging, quenching, tempering, cryogenic treating, sintering, etc.), surface treating processes (e.g., coating, plating, carburizing, decarburizing, case hardening, nitriding, oxidizing, diffusion hardening, etc.), and joining processes (e.g., brazing, diffusion bonding, and soldering, etc.). Articles can be placed on or within the fixture  10  in controlled temperature and chemical environmental enclosures such as, for example, furnaces, ovens, cryogenic baths, molten metal baths, fluidized bed reactors, quench baths, molten salt baths, pickling tanks, passivation tanks, and others. 
     The fixture  10  can comprise a plurality of elongate members  12  comprising a plurality of first elongate members  16  ( 16   a - 16   f ), a plurality of second elongate members  18  ( 18   a - 18   e ), and a plurality of third elongate members  20  ( 20   a - 20   k ). The plurality of first elongate members  16  each extend longitudinally in a first direction X, the plurality of second elongate members  18  each extend longitudinally in a second direction Y that is substantially perpendicular to the first direction X, and the plurality of third elongate members  20  each extend longitudinally in a third direction Z that is substantially perpendicular to the first direction X and the second direction Y. Notably, the fixture  10  may comprise other elongated members that do not extend longitudinally in any of directions X, Y and Z and rather may extend longitudinally in a direction transverse to directions X, Y and Z without departing from the scope of the invention. 
     The plurality of first elongate members  16  can each comprise a rod member  24  having a length L 1  and two end portions  26 , as shown in  FIG. 2 . Furthermore, the plurality of first elongate members  16  can each comprise one or more spacers  28  that the rod member  24  is inserted through. For embodiments with multiple spacers  28 , the spacers  28  can have similar lengths or different lengths with respect to each other. The rod member  24  and the spacers  28  may be substantially cylindrical though in some embodiments, the rod member  24  and the spacers may comprise other shapes. 
     The plurality of first elongate members  16  will preferably all have identical or substantially identical structure. By having identical or substantially identical structure, the manufacturing process for creating the plurality of first elongate members  16  is simplified because the same process can be used for all of the members, thus lowering manufacturing costs for the fixture  10 . However, the plurality of first elongate members  16  may have structure that is different with respect to one another without departing from the scope of the invention. For example, the lengths of the rod member  24  and the one or more spacers  28  may vary for each first elongate member  16 . 
     The plurality of second and third elongate members  18 ,  20  can each comprise a flat stock member  32 , examples of which are shown in  FIGS. 3-6 . The flat stock member  32  comprises a length L 2 , a first major surface  34 , a second major surface  36 , and a thickness T 1  between the first and second major surfaces  34 ,  36 . The flat stock member  32  is made from flat stock and is preferably non-bent such that the first and second major surfaces  34 ,  36  are substantially flat and without bends. By not bending the flat stock member  32 , manufacturing the flat stock member  32  is simplified and costs can be reduced. Moreover, improper bends in the flat stock member  32  can weaken the strength of the flat stock member  32 . It is to be noted, however, that in some embodiments, the flat stock member  32  may be bent without departing from the scope of the invention. 
     The flat stock member  32  can comprise one or more connecting portions  40 , each connecting portion having an aperture  42  extending through the flat stock member  32  from the first major surface  34  to the second major surface  36 . The flat stock member  32  can further comprise one or more intermediate portions  44  joining the connecting portions  40 . For example, the flat stock member  32  can comprise a first connecting portion  40   a  having a first aperture  42   a  extending therethrough along a first axis X 1 , a second connecting portion  40   b  having a second aperture  42   b  extending therethrough along a second axis X 2 , and an intermediate portion  44   a  joining the first and second connecting portions  40   a,    40   b.  In some examples, the flat stock member  32  can comprise more than two connecting portions  40  and apertures  42  and more than one intermediate portion  44 . The axes of the apertures  42  can be substantially parallel to each other and aligned to intersect substantially perpendicular with a longitudinal axis Y 1  of the flat stock member  32 . However, in some examples, the axes can be transverse to each other and/or non-intersecting with the longitudinal axis 
     The flat stock member  32  can comprise a number of different shapes. For example, as shown in  FIGS. 3 &amp; 4 , the first and second major surfaces  34 ,  36  of the flat stock member  32  can comprise a substantially rectangular shape having a width W 1  that is substantially constant along the length L 2  of the flat stock member  32 . The width W 1  can be selected to ensure that the flat stock member  32  meets minimum desired strength properties. 
     Alternatively, as shown in  FIGS. 5 &amp; 6 , the flat stock member  32  can comprise an alternative shape wherein the intermediate portion(s)  44  comprise a width that is less than the widths of each connecting portion  40 . Moreover, the connecting portions  40  can each comprise an edge portion  52  that partially circumscribes the axis of its corresponding aperture  42  and maintains a substantially constant thickness T 2  of material partially about the aperture  42  in the radial direction. For example, the first connecting portion  40   a  can comprise a first edge portion  52   a  that partially circumscribes the axis X 1  of the first aperture  42   a  and the second connecting portion  40   b  can comprise a second edge portion  52   b  that partially circumscribes the axis X 2  of the second aperture  42   b,  maintaining a substantially constant thickness T 2  of material about the first and second apertures  42   a,    42   b  in their radial directions. The thickness T 2  can be selected to meet minimum desired strength properties for the first and second connecting portions  40   a  of the flat stock member  32 . As a result, the first and second connecting portions  40   a,    40   b  will respectively comprise a first and second width W a , W b  that is defined by the selected thickness T 2  of material. Meanwhile, the intermediate portion  44   a  of the flat stock member  32  can comprise an intermediate width W c  that is selected to meet minimum desired strength properties for the intermediate portion  44   a.  Because the intermediate portion  44   a  does not contain any apertures  42 , the intermediate portion  44   a  can comprise an intermediate width W c  that is less than both the first width W a  and the second width W b  while still maintaining a relatively high strength. The alternative shape thus permits the flat stock member  32  to be manufactured with less material than other shapes such as the rectangular shape described above wherein intermediate portions  44  have the same width as the connecting portions  40 . Thus, material costs and overall weight of the fixture  10  can be reduced using the alternative shape. 
     The plurality of second and third elongate members  18 ,  20  can each comprise the flat stock member  32  according to any of the configurations discussed above. Moreover, plurality of second and third elongate members  18 ,  20  need not all comprise the flat stock member  32  according to the same configuration. For example, the shape, size, number of connecting portions  40 , and number of intermediate portions  44  for the flat stock member  32  can vary for each of the second and third elongate members  18 ,  20 . For instance, as can be seen in  FIG. 1 , the length of the plurality of second elongate members  18  can be greater than the length of the plurality of third elongate members  20 . Moreover, the number of connecting portions  40  for the plurality of second elongate members  18  can be greater than the number of connecting portions  40  for the plurality of third elongate members  20 . Preferably, however, the flat stock members  32  for all of the second elongate members  18  are identical or substantially identical to each other and the flat stock members  32  for all of the third elongate members  20  are identical or substantially identical to each other. Still more preferably, the flat stock members  32  for all of the second elongate members  18  and the third elongate members  20  are identical or substantially identical to each other. By having flat stock members  32  that are identical or substantially identical to each other, the manufacturing process for creating the plurality of second and third elongate members  18 ,  20  is simplified because the same process can be used for multiple elongate members, thus lowering manufacturing costs for the fixture  10 . 
     The plurality of elongate members  12  are non-integral with each other and can be movably coupled together to form a support platform  50  for supporting articles that extends along a support plane P, as shown in  FIG. 1 . The plurality of elongate members  12  can also be movably coupled together to form wall portions  54  extending substantially perpendicular to the support plane P to contain the articles on the support platform  50 . One or more of the second and third elongate members  18 ,  20  can be arranged such that their first and second major surfaces  34 ,  36  extend perpendicular to the support plane P. Such an arrangement will help improve the strength of the second and third elongate members  18 ,  20  in the Z direction and thus permit the fixture  10  to carry heavier articles. Preferably, all of the second and third elongate members  18 ,  20  are arranged such that their first and second major surfaces  34 ,  36  extend perpendicular to the support plane P. 
     The plurality of elongate members  12  can be movably coupled together by extending the rod member  24  of one of the first elongate members  16  through the apertures  42  of a second elongate member  18  and a third elongate member  20  and then forming a riveted portion at one or both end portions  26  of the rod member  24 . For example, as can be seen in  FIG. 7 , the rod member  24  of first elongate member  16   a  extends through the aperture  42  of second elongate member  18   a  and the aperture  42  of third elongate member  20   a  and is coupled to the second and third elongate members  18   a,    20   a  by a riveted portion  58  formed at its end portion  26 . The riveted coupling is movable as it allows for differential movement between the elongate members  16   a,    18   a,    20   a,  thus permitting the elongate members  16   a,    18   a,    20   a  to expand, contract, warp, etc. during processing without damaging the coupling. 
     For embodiments wherein one or more of the first elongate members  16  comprises one or more spacers  28 , the one or more spacers  28  can be used to help maintain the structure of the fixture  10  by defining a minimum and/or maximum distance between one of the plurality of second and third elongate members  18 ,  20  and another one of the plurality of second and third elongate members  18 ,  20 . For example, as can be seen in  FIG. 1 , the first elongate member  16   a  comprises a first spacer  28   a  and a second spacer  28   b.  The first spacer  28   a  defines a minimum distance between the second elongate member  18   a  and third elongate member  20   b.  Meanwhile, the second spacer  28   b  defines a minimum distance between the third elongate member  20   b  and second elongate member  18   b.  The minimum distances defined by the spacers  28   a,    28   b  may be identical or substantially identical to each other or different. 
     Turning now to  FIG. 8 , in some embodiments, the fixture  10  can further comprise a handle member  60 . The handle member  60  may comprise one of the elongate members  12  discussed above or the handle member  60  may be a separate component of the fixture  10 . In the present example, the handle member  60  is separate from the elongate members  12  discussed above and comprises a handle portion  62  and two connecting portions  64 . In other examples, the handle member  60  may comprise just one connecting portion  64  or, alternatively, more than two connecting portions  64 . Each connecting portion  64  can comprise an aperture  66  extending through the connecting portion  64 . The handle portion  62  is preferably located above the plurality of elongated members  12  relative to the support plane P such that the handle portion  62  will experience relatively less severe thermal conditions than the lower positioned elongate members  12  during heat treatment processes. 
     The handle member  60  can be movably coupled to the plurality of elongated members  12  by extending the rod member  24  of one of the first elongate members  16  through an aperture  66  of the handle member  60  and an aperture  42  of one of the second elongate members  18  and/or an aperture  42  of one of the third elongate members  20 . A riveted portion at the end portion  26  of the rod member  24  may then be formed to provide a riveted coupling. For example, as can be seen in  FIG. 8 , the rod member  24  of first elongate member  16   a  extends through both apertures  66  of the handle member  60  as well as apertures  42  in the second elongate members  18   a,    18   b  and the third elongate members  20   a,    20   b,    20   c.  Riveted portions  58  are provided at both end portions  26  of the rod member  24 , thereby movably coupling the handle member  60  to the first elongate member  16   a,  the second elongate members  18   a,    18   b,  and the third elongate members  20   a,    20   b,    20   c.    
     In some embodiments, some of the members  12 ,  60  of the fixture  10  may be coupled together using a riveted coupling as described above while some of the members  12 ,  60  may be coupled together using other forms of coupling such as, for example, bolting or welding. In other embodiments, all of the members  12 ,  60  can be movably coupled together using riveted couplings such that all of the members  12 ,  60  are movably coupled to each other without any welding. Preferably, the fixture  10  will have no welding that forms a load-bearing joint between any of its members  12 ,  60 . Coupling the members  12 ,  60  together with riveted couplings instead of welds can allow for members  12 ,  60  of different materials to be coupled together that otherwise could not be coupled together via welds due to the differing properties of their materials. 
     For example, in some embodiments, one of the plurality of elongate members  12  can comprise a first material and another one of the plurality of elongate members  12  that is coupled thereto can comprise a second material that is different from the first material. For instance, as shown in  FIG. 1 , the first elongate member  16   a  can comprise a first material and is coupled to the second elongate member  18   a  and the third elongate member  20   a,  either or both of which can comprise a second material that is different from the first material. More specifically, the first material may comprise carbon steel while the second material comprises nickel alloy, though other materials such as for example, stainless steel, ceramic or some other dissimilar material to the first material may be used in different embodiments. 
     As another example, in some embodiments, the handle member  60  can comprise a first material and one of the plurality of elongate members  12  that is coupled thereto can comprise a second material that is different from the first material. For instance, as shown in  FIG. 8 , the handle member  60  can comprise a first material and is coupled to the first elongate member  16   a,  the second elongate members  18   a,    18   b,  and the third elongate members  20   a,    20   b,    20   c,  any or all of which can comprise a second material that is different from the first material. More specifically, the second material for the elongate members  16   a,    18   a,    18   b,    20   a,    20   b,    20   c  can comprise a high thermal strength material such as, for example, nickel alloy, that can withstand high thermal loads and/or highly corrosive applications/environments. Meanwhile, because the handle member  60  will experience relatively less severe conditions than the alternately positioned elongate members  16   a,    18   a,    18   b,    20   a,    20   b,    20   c,  the first material for the handle member  60  may comprise a material that is lower in thermal strength but less expensive than the first material (e.g., lower alloy metal or carbon steel). 
     As yet another example, in some embodiments, the fixture  10  can comprise a plane of demarcation D that divides the fixture  10  into a top portion  68  and a bottom portion  70 , the top portion  68  being above the bottom portion  70  relative to the support plane P. In such embodiments, the members  12 ,  60  located in the bottom portion  62  can comprise a first material while members  12 ,  60  located in the top portion  60  can comprise a second material. More specifically, the second material for the members  12 ,  60  located in the bottom portion  62  can comprise a high thermal strength material such as, for example, nickel alloy, that can withstand high thermal loads or highly corrosive applications. Meanwhile, because the members  12 ,  60  located in the top portion  60  will experience relatively less severe conditions than the alternately positioned members  12 ,  60  located in the bottom portion  62 , the first material for the members  12 ,  60  located in the top portion  60  may comprise a material that is lower in thermal strength but less costly than the first material (e.g., lower alloy metal or carbon steel). 
     Although the above examples describe embodiments wherein some of the members  12 ,  60  comprise different materials, it is to be noted that in some embodiments, the members  12 ,  60  may all comprise the same material without departing from the scope of the invention. Moreover, although the above examples describe embodiments wherein one of the members  12 ,  60  comprises a first material while another one of the members  12 ,  60  comprises a second material, there may be embodiments wherein other members  12 ,  60  comprise one or more materials dissimilar to the first and second material without departing from the scope of the invention. Indeed, there may be embodiments wherein every one of the members  12 ,  60  comprises a material different from the rest of the members  12 ,  60 . 
     Turning now to  FIG. 9 , in some embodiments, the fixture  10  can further comprise a plurality of stacking members  72 . Each stacking member  72  may be integral with one of the elongated members  12  described above or each stacking member  72  may be a separate component of the fixture  10 . In some embodiments, some of the stacking members  72  may be integral with the elongated members  12  while some of the stacking members  72  may be separate components. In the present example, all of the stacking members  72  are separate components that are coupled to the elongate members  12 . 
     The plurality of stacking members  72  can comprise one or more first stacking members  74  and one or more second stacking members  76 . Each of the first stacking members  74  comprises a first stacking portion  78  while each of the second stacking members comprises a second stacking portion  80 . The first and second stacking portions  78 ,  80  can comprise any structure that can mate and/or interlock with each other. For example, the first stacking portion(s)  78  of the fixture  10  can comprise a recess while the second stacking portion(s)  80  of the fixture  10  can comprise a projection that is receivable within the recess and can interlock with the first stacking portion(s)  78 . As another example, the second stacking portion(s)  80  of the fixture  10  can comprise a recess and the first stacking portion(s)  78  of the fixture  10  can comprise a projection that is receivable within the recess and can interlock with the second stacking portion(s)  80 . 
     The first and second stacking members  74 ,  76  of the fixture  10  can be arranged to mate with stacking members of another fixture. For example, as shown in  FIG. 9 , the first and second stacking members  74 ,  76  of the fixture  10  can be arranged such that when a fixture  110  having identical or substantially identical structure is stacked on top of the fixture  10  with the wall portions  54 ,  154  and stacking portions  78 ,  180  of both fixtures  10 ,  110  being aligned, the first stacking portion(s)  78  of the fixture  10  will mate with the second stacking portion(s)  180  of the second fixture  110 . Likewise, the first and second stacking members  74 ,  76  of the fixture  10  can arranged such that when the fixture  10  is stacked on top of the fixture  110  with the wall portions  54 ,  154  and stacking portions  178 ,  80  of both fixtures  10 ,  110  being aligned, the first stacking portion(s)  178  of the identical fixture  110  will mate with the second stacking portion(s)  80  of the fixture  10 . Thus, the first and second stacking members  72 ,  74  can assist in aligning the fixtures  10 ,  110  when stacking them together by guiding the fixtures  10 ,  110  into alignment with their structure. 
     It is to be noted that the fixture  10  may or may not comprise the plurality of stacking members  72  without departing from the scope of the invention. It is further to be noted that although the fixture  10  may comprise first and second stacking members  74 ,  76  arranged to mate with the first and second stacking members  174 ,  176  of the identical fixture  110 , it is not intended that the identical fixture  110  be present for the fixture  10  to be within the scope of the invention. For example, in some embodiments, the fixture  10  may be stacked with a non-identical fixture. As another example, in some embodiments, a second fixture may not even be present. For instance, the fixture  10  may be by itself but comprise first and second stacking members  74 ,  76  arranged such that when the fixture  10  is stacked with an identical fixture with their wall portions aligned, the first stacking portion(s)  78  of the fixture  10  will mate with the second stacking portion(s) of the identical fixture. 
     Illustrative embodiments have been described, hereinabove. It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention. It is intended to include all such modifications and alterations within the scope of the present invention.