Patent Publication Number: US-2021172643-A1

Title: Hvac duct connection system and flange

Description:
This application claims priority to U.S. Provisional Patent Application No. 62/944,081 filed Dec. 5, 2019, and to U.S. Patent Provisional Patent Application No. 62/949,753 filed Dec. 18, 2019, and to U.S. Patent Provisional Patent Application No. 62/972,951 filed Feb. 11, 2020 all of which are herein incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present application relates generally to duct joining systems used in heating, ventilating, and air conditioning (“HVAC”) systems generally, and to corner flanges utilized to secure duct sections together in particular. 
     2. Background Information 
     Forced air HVAC systems often use air ducts as a conduit for transporting pressurized air in buildings. The air ducts are typically formed in duct sections that are subsequently attached to one another to form longer spans as needed. Duct sections are typically made from sheet metal that is formed to have a rectangular shape defined by orthogonal widthwise walls and heightwise walls. 
     The duct walls of each duct section are also each formed with an end flange that extends outwardly from the respective wall, at each lengthwise end of the duct section. To create an HVAC duct having an extended length, duct sections are positioned lengthwise end-to-end so that the end flanges of one duct section align with the end flanges of an adjacent duct section. 
     The end flanges typically extend only the length of the respective wall and gaps are created at each of the four corners. A pair of L-shaped corner flanges are typically engaged with the end flanges at each corner; e.g., one corner flange of the pair is engaged with the end flanges of a first duct section, and the other corner flange of the pair is engaged with the end flanges of a second duct section. When the duct sections to be joined are positioned lengthwise end-to-end, the corner flange of one duct section is aligned with the corner flange of the other duct section. Fasteners are then used to attach the aligned corner flanges to one another. This occurs at each of the four corners of the duct sections. Typically, the fasteners used to attach the aligned corner flanges to one another are bolt and nut pairs. Clips or self-tapping screws are typically used to attach the aligned end flange portions disposed widthwise or heightwise between the corner flanges. Gaskets may be disposed between the abutting end flanges to prevent leakage between the connecting end flanges. 
     Prior art corner flanges suffer from a number of disadvantages. Corner flange configurations that use bolt and nut pairs require the installer to hold one of the bolt or nut while the other of the bolt or nut is tightened. Hence, the operator typically must use both hands. In installations where access to the duct section corners is problematic, the act of holding one of the bolt or nut while tightening the other can be awkward and time-consuming. Some corner flange configurations that use bolt and nut pairs are configured to utilize a carriage bolt to avoid the need to hold the bolt head; e.g., the corner flange includes a square aperture to receive the square collar portion of the carriage bolt head. The threaded portion of the carriage bolt extends through the same square aperture of the opposing corner flange to receive the nut. The square aperture configured to receive the square collar portion of the carriage bolt head avoids the need to use a tool to hold the bolt, but the carriage bolt must initially be held in place (i.e., square collar held engaged with square aperture) and the nut must be threaded onto the carriage bolt. Hence, although the carriage bolt obviates the need for two tools, the installer must still use two hands during the initial installation. 
     What is needed is a corner flange that overcomes the disadvantages of the prior art corner flanges. 
     SUMMARY 
     According to an aspect of the present disclosure, an HVAC duct section connection system is provided that includes a first corner flange, a second corner flange, and at least one self-threading bolt. The first corner flange and the second corner flange each include a first leg, a second leg, an interior surface, an exterior surface, and at least one fastener aperture. The first and second legs are integrally connected to one another at a respective first end, and each leg extending outwardly away from the respective first end away from the other leg. The interior surface and the exterior surface extend along the first and second legs, and the exterior surface is disposed opposite the interior surface. The at least one fastener aperture extends between the interior surface and the exterior surface. The fastener aperture includes an integrally formed truncated cone extending out from the exterior surface. The truncated cone has an inner diameter. The self-threading bolt has a shank and a head, the shank having a threaded section with a thread diameter sized to engage the inner diameter of the truncated cone. 
     In any of the aspects or embodiments described above and herein, the truncated cones of the first corner flange and the second corner flange may include plastically deformed material. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include at least one slit. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include a plurality of slits and a plurality of cone sections, wherein adjacent cone sections are separated from one another by a one of said plurality of slits. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include at least one wall failure element. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include an inner diameter surface, and the at least one wall failure element may be disposed in the inner diameter surface. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include an outer diameter surface, and the at least one wall failure element may be disposed in the inner outer surface. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include an inner diameter surface and an outer diameter surface, and the at least one wall failure element may be a plurality of wall failure elements, and at least one of the wall failure elements may be disposed in the inner diameter surface, and at least one of the wall failure elements may be disposed in the outer diameter surface. 
     In any of the aspects or embodiments described above and herein, the shank of the at least one self-threading bolt may include a threaded portion having a first diameter and an unthreaded section having a second diameter, the second diameter is less than the first diameter. The unthreaded section may be disposed between the threaded section and the head, and the first diameter sized so that the threaded portion threadably engages the inner diameter of the truncated cone. 
     In any of the aspects or embodiments described above and herein, the integrally formed truncated cone may have an engagement length that is at least long enough to have two circumferential threads of the threaded section engaged with the truncated cone. 
     According to another aspect of the present disclosure, a method of joining together duct sections of an HVAC duct is provided. Each duct section includes a plurality of end flanges. The method includes: a) providing a first corner flange and a second corner flange, the first corner flange including: a first leg and a second leg, the first and second legs integrally connected to one another at a respective first end, and each leg extending outwardly away from the respective first end away from the other leg; an interior surface extending along the first and second legs; an exterior surface extending along the first and second legs, the exterior surface disposed opposite the interior surface; and at least one fastener aperture extending between the interior surface and the exterior surface, the fastener aperture including an integrally formed truncated cone extending out from the exterior surface, wherein the truncated cone has an inner diameter; b) providing at least one self-threading bolt having a shank and a head, the shank having a threaded section with a thread diameter sized to engage the inner diameter of the truncated cone; c) disposing the first corner flange in contact with a first pair of end flanges of a first duct section; d) disposing the second corner flange in contact with a second pair of end flanges of a second duct section; and e) joining the first and second duct sections together, the joining including passing a one of the at least one self-threading bolt through an aperture in the second corner flange, and threadably engaging the one of the at least one self-threading bolt with the truncated cone of the first corner flange until the first pair of end flanges and the second pair of end flanges are in contact with one another. 
     In any of the aspects or embodiments described above and herein, the second corner flange may be configured the same as the first corner flange. 
     In any of the aspects or embodiments described above and herein, the shank of the at least one self-threading bolt may include a threaded portion having a first diameter and an unthreaded section having a second diameter, the second diameter is less than the first diameter, the unthreaded section disposed between the threaded section and the head, the first diameter sized so that the threaded portion threadably engages the inner diameter of the truncated cone of the first corner flange during the joining step. 
     In any of the aspects or embodiments described above and herein, the at least one self-threading bolt may be threadably engaged with the truncated cone of the first corner flange until the unthreaded section is disposed within the truncated cone of the second corner flange. 
     According to another aspect of the present disclosure, a duct corner flange is provided that includes a first leg, a second leg, an interior surface, an exterior surface, and at least one fastener aperture. The first and second legs are integrally connected to one another at a respective first end, and each leg extends outwardly away from the respective first end away from the other leg. The interior and exterior surfaces extend along the first and second legs. The exterior surface is disposed opposite the interior surface. The fastener aperture extends between the interior surface and the exterior surface. The fastener aperture includes an integrally formed truncated cone extending out from the exterior surface. The truncated cone comprises plastically deformed material. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include at least one slit. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include a plurality of slits and a plurality of cone sections, wherein adjacent cone sections are separated from one another by a one of said plurality of slits. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include at least one wall failure element. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include an inner diameter surface, and the at least one wall failure element may be disposed in the inner diameter surface. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include an outer diameter surface, and the at least one wall failure element may be disposed in the outer diameter surface. 
     In any of the aspects or embodiments described above and herein, the truncated cone may include an inner diameter surface and an outer diameter surface, and the at least one wall failure element is a plurality of wall failure elements, and at least one of the wall failure elements is disposed in the inner diameter surface, and at least one of the wall failure elements is disposed in the outer diameter surface. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of duct sections of an HVAC duct joined together at lengthwise ends. 
         FIG. 2  is a partial view of a duct section corner. 
         FIG. 3  is a planar view of a present disclosure corner flange embodiment. 
         FIG. 4  is a sectional view of a fastener aperture portion of the corner flange embodiment shown in  FIG. 3 . 
         FIG. 5  is a planar view of a present disclosure corner flange embodiment. 
         FIG. 6  is a sectional view of a fastener aperture portion of the corner flange embodiment shown in  FIG. 5 . 
         FIG. 6A  is a planar view of an embodiment of a fastener aperture portion of a corner flange embodiment. 
         FIG. 6B  is a planar view of an embodiment of a fastener aperture portion of a corner flange embodiment. 
         FIG. 6C  is a planar view of an embodiment of a fastener aperture portion of a corner flange embodiment. 
         FIG. 7  is a sectional view of a fastener aperture portion of the corner flange embodiment. 
         FIG. 8  is a planar view of an embodiment of a fastener aperture portion of a corner flange embodiment. 
         FIG. 9  is a planar view of an embodiment of a fastener aperture portion of a corner flange embodiment. 
         FIG. 10  is a sectional view of a fastener aperture portion of the corner flange embodiment. 
         FIG. 11  is a diagrammatic sectional view of duct sections connected by present disclosure corner flange embodiments. 
         FIG. 12  is a perspective view of a bolt embodiment. 
         FIG. 12A  is a diagrammatic cross-sectional view of the shank portion of the bolt embodiment shown in  FIG. 12 . 
         FIG. 13  is a diagrammatic perspective view of duct sections connected by present disclosure corner flange embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a forced air HVAC system often uses air ducts  10  as a conduit for transporting pressurized air in buildings. The air ducts  10  are typically formed in duct sections  10 A,  10 B that are subsequently attached to one another to form a longer lengthwise extending span as needed. Duct sections  10 A,  10 B are typically made from sheet metal that is formed to have a rectangular shape defined by orthogonal widthwise walls  12  and heightwise walls  14 . Each wall  12 ,  14  of the duct section includes an end flange  16 . To create an HVAC duct having an extended length, duct sections  10 A,  10 B are positioned lengthwise end-to-end so that the end flanges  16  of one duct section  10 A align with the end flanges  16  of an adjacent duct section  10 B. 
     A corner flange  18  is typically disposed at each corner of a respective duct section  10 A,  10 B, in contact with the end flanges  16 . Very often, the end flanges  16  may be peened over, or crimped, or otherwise bent, to hold the respective corner flange  18  in place relative to the end flange  16 . The respective duct sections  10 A,  10 B may be attached to one another by securing the opposing corner flanges  18  at each corner to one another (e.g., using fasteners). 
     The present disclosure corner flange  18  embodiments obviate the need to use a bolt and nut pair to attach the opposing corner flanges to one another. Referring to  FIGS. 3-6 , a corner flange  18  is provided having an “L” shaped body with a first leg  20  and a second leg  22 . The first leg  20  and the second leg  22  are joined to one another (e.g., a unitary structure), and extend outwardly from each other in substantially perpendicular directions. The corner flange  18  is typically made from a metallic material; e.g., a mild steel, aluminum, etc. The corner flange  18  includes an interior surface  24  and an opposite exterior surface  26 . The corner flange  18  includes at least one fastener aperture  28 . The fastener aperture  28  includes a truncated cone  30  of material extending outwardly from the exterior surface  26  of the corner flange  18 . The truncated cone  30  has a bore  32  defined by an inner diameter surface  34 . The bore  32  extends lengthwise along a central axis  35  from the interior surface  24  of the corner flange  18  to an end surface  36 . At least a portion of the truncated cone bore  32  may have a constant diameter. 
     The truncated cone  30  may be formed by a deformation process (e.g., a mechanical punch process) that plastically deforms corner flange body material outwardly to create the aforesaid truncated cone  30 . A non-limiting example of how a truncated cone  30  may be formed involves drilling or otherwise forming an initial aperture  38  having a diameter D 1  (shown diagrammatically in phantom line in  FIG. 5 ) extending through the corner flange body; e.g., providing a through hole that extends between the interior surface  24  and the exterior surface  26  of the corner flange body. Subsequently, the flange  18  at the initial aperture  38  may be deformed mechanically. For example, a mechanical punch may be used to mechanically deform the aperture  38 , which punch is configured to form an aperture portion having an inner diameter D 2  (where D 2  is greater than diameter D 1 ) while being forced into the aperture  38  from the interior surface  24 . The geometry of the punch causes some amount of corner flange body material surrounding the initial aperture  38  to plastically deform and move outwardly from the exterior surface  26  of the corner flange body. The truncated cone bore is sized so that the threads of the self-threading bolt engage with the material of the truncated cone  30  to create a threaded engagement between the truncated cone  30  and the self-threading bolt. In other words, the diameter of the bore  32  created within the truncated cone  30  is chosen relative to the size of a self-threading bolt used to secure the corner flanges  18  together, or vice versa. Preferably, the bore is circular, or at least substantially circular, to ensure substantial circumferential thread engagement with the bolt. In addition, the truncated cone is formed to have a thread engagement length (“EL”) that is adequate, in combination with the circumferential thread engagement, to accommodate the amount of force required to hold the corner flanges together under normal operational circumstances. In most HVAC duct applications, the corner flange bolt diameter is three-eighths of an inch (⅜″), and has a course thread (e.g., twelve threads per inch). In such applications, the EL of the truncated cone  30  is preferably long enough to permit circumferential engagement with at least two threads of a bolt (e.g., bolt  42  as shown in  FIG. 11 ). The present disclosure corner flanges are not limited to use with circular bolts, or any particular diameter bolt, or any particular bolt thread configuration. 
     In the embodiment shown in  FIGS. 5 and 6-6C , the truncated cone  30  includes a plurality of cone sections (i.e.,  30 A,  30 B in  FIGS. 5 and 6 ;  30 A,  30 B,  30 C in  FIG. 6B , etc.) separated by one another by voids (each void hereinafter referred to hereinafter as a slit  40 ); e.g., adjacent cone sections  30 A,  30 B are separated from one another by a slit  40 . The present disclosure is not limited to forming the slits  40  by any particular process. Each cone section  30 A,  30 B forms a quasi-cantilever element that acts elastically when forced radially outwardly (e.g., when a bolt is threaded into the aperture), producing a radially inward biasing force. The exemplary embodiment shown in  FIGS. 5 and 6  shows two cone sections  30 A,  30 B. The exemplary embodiment shown in  FIG. 6A  illustrates a truncated cone  30  that includes a single slit  40 . The exemplary embodiment shown in  FIG. 6B  shows three slits  40 , and three cone sections  30 A,  30 B,  30 C. The exemplary embodiment shown in  FIG. 6C  shows four slits  40 , and four cone sections  30 A,  30 B,  30 C,  30 D. The present disclosure is not limited to any particular number of number of slits  40 /cone sections. In the embodiment shown in  FIG. 7 , the truncated cone  30  includes one or more apertures  41 . In contrast to a slit  40 , an aperture  41  disposed within the wall(s) that forms the truncated cone  30  does not break through the end surface  36  of the truncated cone  30 . The aperture  41  shown in  FIG. 7  may be referred to as a slot, having a greater length (extending along a major axis) than a width (extending along a minor axis). The present disclosure is not limited to any particular aperture configuration; e.g., slots, circular, oval, etc. The present disclosure is not limited to any particular orientation of the aperture  41  within the wall of the truncated cone  30 . For example, if the aperture  41  is asymmetric (i.e., has a major axis longer than a minor axis), the major axis may be aligned with the central axis  35  of the aperture  28 , or the major axis may be perpendicular to the central axis  35  of the aperture  28 , or the major axis may be skewed at a non-perpendicular angle to the central axis of the aperture  28 , etc. 
     In the embodiment shown in  FIGS. 8 and 9 , a truncated cone  30  is formed to include at least one wall failure element  50  (e.g., a reduced thickness wall portion). The wall failure element  50  is configured such that when a bolt is threaded into the truncated cone  30  (as will be described below), the truncated cone  30  will fail (e.g., mechanically shear), at or near the wall failure element  50  and the truncated cone  30  will thereafter be circumferentially discontinuous.  FIG. 8  illustrates an embodiment wherein a pair of wall failure elements  50 A,  50 B are disposed in the inner diameter surface  34  of the truncated cone  30 , diametrically opposite one another.  FIG. 9  illustrates an embodiment wherein a first pair of wall failure elements  50 C,  50 D are disposed in the inner diameter surface  34  of the truncated cone  30  and a second pair of wall failure elements  50 E,  50 F are disposed in the outer diameter surface of the truncated cone  30 . Each first wall failure element  50 C,  50 D may be aligned with a second wall failure element  50 E,  50 F to produce a reduced thickness wall portion there between. When a bolt is threaded into the truncated cone  30  (as will be described below), the truncated cone  30  will fail at the wall failure element positions and the truncated cone  30  will thereafter include a first cone section  30 A and a second cone section  30 B. In some embodiments, a wall failure element  50  may be configured such that when a bolt is threaded into the truncated cone  30 , the truncated cone  30  will elongate at or near the wall failure element  50  rather than fail. 
     In any of the truncated cone embodiments disclosed herein, at least a portion of the bore  32  of the truncated cone  30  may be threaded to facilitate threaded engagement with a fastener.  FIG. 10  diagrammatically illustrates a truncated cone  30  having a bore  32  portion that is threaded; e.g., threads  33 . 
     In some embodiments (e.g., see  FIG. 11 ), a self-threading bolt  42  is used that includes a shank  44  and a head  46 . A portion of the shank  44  is threaded with a self-threading type of thread. Between the threaded portion of the shank  44  and the head  46 , the shank  44  includes an unthreaded section  48 . The unthreaded section  48  is configured to not engage with threads cut into the truncated cone  30 . The axial length of the unthreaded section  48  may be equal to or greater than the axial length of the threaded portion of the truncated cone (the “threaded portion” may be threaded as a result of engagement with the self-threading portion of the shank). As a result, once the unthreaded section  48  is received completely within the threaded portion of the truncated cone  30 , the bolt  42  is non-engaged with that truncated cone and is free to rotate without thread engagement. In some embodiments, the unthreaded section  48  may have a reduced diameter. In these embodiments, once the unthreaded portion is disposed within the truncated cone  30 , the bolt  42  is captured by the flange  18  and cannot be separated; i.e., will not fall out of the truncated cone  30 , thereby greatly facilitating assembly of the duct work. In addition, the unthreaded portion  48  provides clearance so that the axis of the bolt  42  can be misaligned (e.g., canted) with the axial axis of the truncated cone  30 . As a result, small misalignments between the truncated cones of flange pairs can be accommodated during assembly. In some embodiments, the length of the unthreaded section  48  of the shank  44  may be great enough such that the threaded portion will pass through the respective truncated cone  30  of both corner flanges  18  during assembly. In these embodiments, the unthreaded section  48  will be disposed in the truncated cones  30  of both corner flanges after assembly, and the threaded portion (now disposed outside the second corner flange  18 ) will operate to prevent the corner flanges  18  from being separated from one another. The present disclosure is not limited to any particular type of bolt. The bolt  42  shown in  FIG. 11  is circularly configured for a least a portion of the shank. Another example of a bolt that may be used with the present disclosure is a bolt  142  having a tri-lobular shank  144  (sometimes referred to a as a “tri-round” shank) and a head  146  as shown in  FIGS. 12 and 12A . The present disclosure is not limited to any particular bolt configuration; self-threading, threaded, cylindrical shank, tri-lobular shank, etc. In addition, the present disclosure is not limited to any particular bolt head configuration; e.g., the head of the bolt  42  may be configured for driving by any conventional driver such as a hex-head driver, a double spline driver, a Torx driver, etc. 
     Referring to  FIGS. 11 and 13 , in the assembly of a pair of duct sections  10 A,  10 B, in each corner of the duct sections  10 A,  10 B a pair of corner flanges  18 A,  18 B are utilized to attach the duct sections  10 A,  10 B to one another. Each corner flange  18 A,  18 B is disposed at a corner of the duct sections and the flanges  18 A,  18 B are attached to one other with the respective duct section end flanges  16  captured there between to strengthen the connection between the duct sections  10 A,  10 B.  FIG. 13  shows a diagrammatic example of a first corner flange  18 A attached to a second corner flange  18 B by a self-threading bolt  42 , thereby attaching the first duct section  10 A to a second duct section  10 B.  FIG. 11  diagrammatically shows a sectional view of the first and second corner flanges  18 A,  18 B shown in  FIG. 13 . As can be seen in  FIG. 11 , the self-threading bolt  42  is threaded through the truncated cone  30  of the first corner flange  18 A, and then engages the truncated cone bore  32  of the second corner flange  18 B. As the self-threading bolt  42  engages the truncated cone  30  of the second corner flange  18 B, the unthreaded section  48  of the bolt shank  44  is received within the truncated cone  30  of the first corner flange  18 A. Tightening the self-threading bolt  42  consequently draws the first and second corner flanges  18 A,  18 B together, thereby securing the first and second duct sections  10 A,  10 B together. 
     In those instances wherein a corner flange  18  having a truncated cone  30  with cone sections  30 A,  30 B and slits  40  is used, the self-threading bolt  42  is threaded through the truncated cone  30  of the first corner flange  18 A, and then engages the truncated cone bore  32  of the second corner flange  18 B. As the self-threading bolt  42  engages the truncated cone  30  of the second corner flange  18 B, the cone sections  30 A,  30 B will elastically bend radially outward to some degree. The self-threading bolt  42  engages with each cone section  30 A,  30 B in a manner similar to when the truncated cone  30  does not include slits  40 . In the embodiment that utilizes cone sections  30 A,  30 B, however, the force required to engage the cone sections  30 A,  30 B may be decreased relative to a truncated cone  30  without slits  40 , and the biasing force of the cone sections  30 A,  30 B promotes continued engagement between the cone sections  30 A,  30 B and the self-threading bolt  42 . Here again, once the bolt  42  is sufficiently engaged with the truncated cone  30  of the first corner flange  18 A, the unthreaded section  48  of the bolt shank  44  is received within the truncated cone  30  of the first corner flange  18 A. Tightening the self-threading bolt  42  consequently draws the first and second corner flanges  18 A,  18 B together, thereby securing the first and second duct sections  10 A,  10 B together. 
     In those instances wherein a corner flange  18  having a truncated cone  30  with wall failure elements  50  is used, the self-threading bolt  42  is threaded through the truncated cone  30  of the first corner flange  18 A, and then engages the truncated cone bore  32  of the second corner flange  18 B. When a sufficient amount of the self-threading bolt  42  is engaged with the truncated cone  30  of the second corner flange  18 B, the wall failure elements  50  will fail (e.g., shear or plastically elongate) and the cone sections  30 A,  30 B will elastically bend radially outward to some degree. The self-threading bolt  42  engages with each cone section  30 A,  30 B in a manner similar to when the truncated cone  30  does not include the wall failure elements  50 . The force required to engage the cone sections  30 A,  30 B may be decreased relative to a truncated cone  30  without wall failure elements  50 , and the biasing force of the cone sections  30 A,  30 B promotes continued engagement between the cone sections  30 A,  30 B and the self-threading bolt  42 . Here again, once the bolt  42  is sufficiently engaged with the truncated cone  30  of the first corner flange  18 A, the unthreaded section  48  of the bolt shank  44  is received within the truncated cone  30  of the first corner flange  18 A. Tightening the self-threading bolt  42  consequently draws the first and second corner flanges  18 A,  18 B together, thereby securing the first and second duct sections  10 A,  10 B together. 
     Although the invention has been described and illustrated with respect to exemplary embodiments thereof, the foregoing and various other additions and omissions may be made therein and thereto without departing from the spirit and scope of the present invention. For example, the exemplary embodiments described above illustrate a corner flange with a single aperture with a truncated cone located at the intersection between the legs of the corner flange. In alternative embodiments, a corner flange may include a plurality of apertures with truncated cones, and/or one or more apertures with truncated cones located at positions other than the intersection between the legs of the corner flange. 
     Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.