Rectangular and square ducting systems

A duct structure (50), includes lengths of square/rectangular duct (52) manufactured by pre-forming the duct in round cross-section (51) and then transforming the round cross-section into square and rectangular cross-sections utilizing expandable die structures (58). The duct (52) may be connected together end to end by flanged connectors (54) formed from strip stock (71), that is notched at locations that correspond to the corners of the formed flange connector. The cross-sectional profile of the flanged connector is then formed by roll forming and/or bending and/or other techniques. Thereafter, the strip stock is bent at its notched locations to define the corners (80) of the flange connector (54) and then the free ends of the strip stock are fixed together.

FIELD OF THE INVENTION

The present invention relates to rectangular and square heating, ventilating and air conditioning (HVAC) ducting and methods of making and interconnecting such ducting.

BACKGROUND OF THE INVENTION

Square and rectangular ducting are widely used in HVAC systems. Such ducting can be located between floor or ceiling joists whereas ducting of other cross-sectional shapes, such as round, may not fit in such locations and still be sufficiently large enough in size to handle the HVAC load required.

Referring toFIGS. 1–3, it is known to manufacture square and rectangular ducting structures such as structure20, by bending a sheet of thin-gauge material to form the corners and the four walls of a length of ducting22and then join the duct together along one corner24to form an integral structure. This corner joint may take various forms, such as by overlapping portions of the ducting and then screwing the overlapped portions together, or by utilizing an “S” shaped flange26or other shaped member to join the ducting along corner24. Typically, lengths of square and rectangular ducting produced in this manner are relatively limited in length due to the size of the brake press or other machinery used to form the corners of the ducting and also limited by the length of the sheet metal stock available.

Because square and rectangular cross-section HVAC ducting is typically of relatively short lengths, it is necessary to connect ducting sections end-to-end to achieve a desired overall length. In this regard, as shown most clearly inFIGS. 1 and 2, a face flange structure28is integrally formed at the ends of each wall of the duct22. The face flange structure has a mating or face section30extending perpendicularly to the corresponding wall of duct22and a reinforcement hem structure32extending transversely from the distal edge flange face30. The hem structure32may be folded over on itself to form a double thick section for additional strength. InFIG. 1, the hem structure32is folded inwardly on itself whereas inFIG. 2, the hem section is folded outwardly on itself.

As will be appreciated by the foregoing construction, it is not possible to extend the face flanges28to occupy the entire corner at the juncture between two adjacent panels of the ducting structure20. Such open corners are “filled in” by an angle bracket34that typically nests with the adjacent portions of the face flange structures28.FIG. 1shows the angle brackets34prior to installation, whereasFIG. 2illustrates the angle flanges in installed positions. The angle flanges include corner apertures35for receiving a hardware fastener36therethrough. The hardware fastener may be in the form of a threaded screw that mates with a nut38. In this manner, the face flange structures28are connected together in face-to-face relationship at the corners of the ducting structure20. A flat or other shaped gasket40may be interposed between adjacent flange faces30in an effort to provide an airtight seal therebetween.

However, a sufficient seal usually is not achieved through the use of only the angle brackets34. As such, typically formed clips40are used to also retain the adjacent face flange structures28together in an engaged face-to-face relationship. As shown inFIG. 2, the clip40is shaped and sized to wrap around the reinforcement hem structures32of the face flange structures28.

Referring toFIG. 3, typically reinforcing members are needed to increase the structural integrity of ducting sections20and to prevent the ducting sections from unduly vibrating.FIG. 3illustrates such reinforcing members in the form of “Z” brackets42that extend transversely across duct22, with one of the flange sections of the brackets attached to the duct by hardware members, welding or otherwise.

It can be appreciated that the prior art ducting structure shown inFIGS. 1–3is time-consuming and expensive not only to fabricate, but also to assemble and install in the field. The present invention is directed to more economical and faster methods for manufacturing, assembling and installing HVAC ducting of a rectangular or square cross-section.

SUMMARY OF THE INVENTION

A ducting structure of a square or rectangular cross-section is formed from round duct sections that are transformed into square or rectangular cross-sections by an expansion apparatus composed die structures of structures that press against the interior of the round cross-sectional duct to force the duct to assume a desired square or rectangular cross-sectional shape.

The square or rectangular cross-sectional duct sections are inner-connected by formed flanged connectors that may be of numerous possible profiles. Each of the flanged connectors does include an insertion section that engages into, or over, the adjacent end portion of the duct section, and a mating flange extending substantially perpendicularly to the insertion section to form a mating surface for face-to-face engagement with the flanged connector of the adjacent duct section. Preferably, but optionally, a re-enforcing section is disposed at the outer perimeter portion of the mating flange. The re-enforcing section may be of numerous configurations, and may include a hem section that extends outwardly from the mating flange and also optionally a return section to enhance the structural integrity and stiffness of the re-enforcing section.

The flanged connectors are formed from strip stock that is notched at it ends and also at other locations along its length to define the location of the corners of the flanged connector. The desired cross-sectional profile of the flanged connector is formed into the strip stock by roll forming, bending, or other well-known processes. Thereafter, the partially formed strip stock is bent at the notch locations to form the corners of the rectangular or square shaped flanged connector. The free ends of the strip stock are then affixed together to form a rigid structure. The thus-formed flanged connector can be attached to the end of a duct section so that adjacent duct sections can be coupled together.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 9illustrates a HVAC duct structure50constructed in accordance with the present invention. The structure50includes a length of ducting52constructed in accordance with the present invention and a formed flanged connector ring54also constructed in accordance with the present invention and illustrated as affixed to the adjacent end of the ducting.

Next, referring toFIGS. 4–6, one method of manufacturing the duct52is illustrated. In accordance with the present invention, round cross-sectional ducting51is first prefabricated. Preferably, the preformed duct51is in the form of a spiral-seam tube composed of a helically wound sheet metal strip, with the strip edges interconnected to each other by formed lock seams. This is a standard, well-known method of manufacturing round ducting from a continuous sheet metal strip. In this regard, see for example, U.S. Pat. Nos. 3,263,321 and 3,474,514, which are incorporated herein by reference.

The round, preformed ducting51is placed over an expansion apparatus56which extends lengthwise within the interior of the round duct. The apparatus56includes a pair of spaced apart die structures58, each having an outwardly directed, substantially flat face60and upper and lower edge sections62and64extending transversely from the face. The die structures58may be pushed apart from each other by linear actuators68so that the outward faces60thereof move in the direction of the arrows66shown inFIG. 5while maintaining a parallel relationship to each other. As the die structures move outwardly, they cause the round duct51to press against the outward faces60and also to press against the upper and lower die edges62and64, thereby to transform the round duct51into a rectangular cross section duct52, shown inFIG. 6. Thereafter, the linear actuators68may be activated to retract the die structures58to their initial position shown inFIG. 5so that the formed duct52can be removed.

The linear actuators68may be of various types and configurations, including, for example, hydraulic cylinders, pneumatic cylinders, etc. Moreover, guideways or guide structures may be employed to assist in maintaining the die outward faces60parallel to each other, especially when being extended outwardly in the direction of arrows66.

FIGS. 7 and 8illustrate an alternative embodiment of expansion apparatus56wherein the die structures58′ have rounded corners70in place of the sharp corners of die structure58. The components of expansion apparatus56′ that correspond to those components of expansion apparatus56are designated with the same part number but with a prime (“′”) designation. As shown inFIG. 8, the use of expansion apparatus56′ results in a duct52′ having rounded corners rather than relatively sharp corners of the duct52shown inFIG. 6. The rounded corners are thought to provide more efficient airflow through the duct.

It will be appreciated that expansion apparatus56and56′ can be utilized to form a square cross-sectional shapes and/or rectangular cross-sectional shapes of various sizes depending on the extent to which the die structures58/58′ are expanded. Also, round pre-form ducting which is longer than the length of the die structure58/58′ may be formed by first transforming one end of the round ducting51and then removing the partially formed ducting from the expansion apparatus and inserting it over the die structures58/58′ in a reverse direction, to transform the opposite end of the ducting51into the desired cross-section.

Other methods could be utilized to form duct52/52′ in addition to expansion apparatus56and56′. In this regard, an expansion mandrel could be pulled through the round preformed ducting51. Lengthwise, such expansion mandrel could be circular at a first end having a diameter somewhat smaller than the inside diameter of the preformed ducting51. From the first end the expansion mandrel could progressively transform from a rounded to a square or rectangular shape of the desired final cross-section of ducting52. One possible advantage of such an expansion mandrel is that it could be utilized with virtually any length of round preformed ducting51.

Next, methods for making flanged connector ring54will be described. Initially referring toFIG. 10, the one piece connector ring54may be manufactured from a length of strip stock/material71having notches72stamped or otherwise cut out of its ends as well as intermediate notches74stamped or otherwise cut out along the length of strip stock71. Alignment holes76, as discussed more fully below, may also be stamped, punched or otherwise cut out of the strip stock71. The intermediate notches74are located at what will become the corners of the flanged connector ring54, and the ends of the strip stock will form the fourth corner of the flanged connector ring, as discussed below. The intermediate notches74preferably do not “break out” to the edge of the strip stock. Rather, a thin section78of strip stock is retained, which will assist in forming the strip stock into a desired profile with less distortion, as discussed below. Each of the intermediate notches74includes a rectangular/square portion adjacent thin section78and a triangular section opposite thin section78. The apex of such triangular section corresponds to the center of a corner80of the flanged connector ring54.

The flat strip stock71is then formed into a desired profile using rolling and/or bending and/or other well-known techniques. One profile for the connector ring54is shown inFIG. 9. This profile corresponds toFIG. 15, which illustrates a cross-sectional view of the connector ring shown inFIG. 9.

The flanged connector ring54can be manufactured by first bending or rolling the strip stock71lengthwise into an angle shape, as shown inFIG. 19, with a brake press or with rollers as is well known in the art. The vertical leg of the angle shape shown inFIG. 19corresponds to the insertion section82, of the formed connector54, seeFIGS. 9 and 15. Thereafter, the horizontal leg of the now angle-shaped strip stock71is further formed by a first roller set84, consisting of a first roller assembly86, having a major diameter roller88, and a side-by-side smaller roller90, mounted on a rotatable shaft92. The first roller set84also includes a second roller assembly94consisting of a roller96, mounted on a rotatable shaft98. The rotatable shafts92and98may be moved towards and away from each other in a substantially parallel orientation in a well-known manner. When the shafts are moved towards each other, the roller96, while positioned at the side of the roller88, turns a portion of the horizontal leg of the preformed strip stock downwardly to partially form a reinforcing section100, thereby also defining the width of the mating face section102of the formed connector54. The reinforcing section100is captured between the adjacent face sections of the rollers88and96. In addition, a horizontal segment104of the reinforcing section100is formed between the outer diameter of roller96and the outer diameter of roller90. The vertically disposed segment of the reinforcing section100serves a hem section of the connector54, and the horizontal segment104will be formed to serve as a return section of the connector, as discussed below.

The partially formed flanged connector54ofFIG. 20is placed in a roller set110ofFIG. 21for further processing. The roller set110includes a die roller assembly112composed of a die roller114mounted on a rotatable shaft116. The die roller114has a grove118formed around its parameter in a shape of a half “V” composed of a vertical face120and a diagonal face122. The roller set112also includes a second roller assembly124composed of a cylindrical roller126mounted on a rotatable shaft128. The roller assemblies114and124are capable of moving towards and away from each other while the rotatable shafts116and128remain substantially parallel to each other. As shown inFIG. 21, the partially formed flanged connector54fromFIG. 20is positioned relative to roller114so that hem section106is adjacent vertical face120of roller114. Thereafter, the roller assemblies112and124are moved towards each other as the rollers114and126rotate relate to each other thereby causing the return section104to assume the orientation of diagonal roller face122relative to roller face120, as shown inFIG. 22.

Thereafter, the partially formed flanged connector54in the configuration ofFIG. 22is further formed by a roller set130shown inFIG. 23. The roller set130consists of a pair of roller assemblies132and134, each composed of a roller136and138carried by corresponding rotatable shafts140and142. As shown inFIG. 23, the hem section106and the partially formed return flange104are placed between the two rollers136and138, and then the two rollers are moved towards each other while rotating, thereby to pinch the end section and the return section, therebetween so that the return section closely overlies the end section thereby completing the formation of the reinforcing section100, as well as partially completing the overall formation of the flanged connector54, as shown inFIG. 24. The cross-sectional shape ofFIG. 24corresponds to the view of the partially formed flanged connector shown inFIG. 13.

FIGS. 25,26,27, and28, illustrate another method of pre-forming flanged connector54. As illustrated, the insertion section82and the mating flange102, of the flanged connector, are formed by bending strip stock71with the press or with rollers, as described above. Thereafter, the mating flange portion102, and the material extending outwardly therefrom that will eventually form the hem section106, and return section104, of the connector is placed over a roller set150to partially form the hem section106and return section104, as shown inFIG. 26. The roller set150includes a first roller assembly152consisting of a roller die154mounted on a rotatable shaft156. A “V” shaped groove158extends around the circumference of the roller die154to match the outer parameter profile of a roller die160mounted on a rotatable shaft162of roller assembly164. The roller assemblies152and164are capable of moving towards and away from each other while their respective shafts156and162, rotate and maintain an orientation substantially parallel to each other. As a consequence, when the outer marginal portion of the mating flange102is placed in alignment with groove158and then the roller dies154and160are engaged with each other, they cooperatively form hem section106and return section104in the orientation shown inFIG. 26.

Thereafter, the partially formed flanged connector shown inFIG. 26is further worked by a roller set230shown inFIG. 27. The roller set230corresponds to the roller set130shown inFIG. 23, with the description set forth above with respect toFIG. 23applying toFIG. 27, but with the part numbers increased by 100. Thus, such description will not be repeated. The results of roller set230is a partially formed flanged connector54as shown inFIG. 28. The cross-sectional view ofFIG. 28corresponds to the longitudinal view of the partially formed connector54shown inFIG. 13.

The partially formed flanged connector54, shown inFIG. 13, is then bent at the center of notches74represented by bend line75to form a connector of the shape shown inFIG. 9. It will be appreciated that due to the notches74, the rolled strip stock is readily bent at such notches. It may or may not be necessary to utilize a binding jig. The free ends of the formed flanged connector shown inFIG. 9are fastened together, such as by welding. Moreover, each of the other three corners of the flanged connector is composed of a miter-joint. As such it is preferable to close these joints by welding the diagonal intersection246of the adjacent mating flange segments102, as well as the corner intersection248of the adjacent segments of the insertion section82, seeFIG. 9. In this manner, the formed flanged connector constitutes a structurally sound and strong member capable of securely fastening duct structures together in end-to-end relationship. Such duct structures may be aligned with each other through the use of aligning holes76shown inFIG. 9. Also, a gasket, a bead of caulk, or other sealant can be applied to the outward faces of adjacent mating flanges102to form an air tight seal therebetween. It will be appreciated that before the flange connector is bent at bend line75, the thin section78between the notches74and the edge of the strip stock72, are cut, snipped, clipped, or otherwise removed.

FIGS. 11 and 12show alternative configures of strip stock71, identified as part Nos.71′ and71″. The corresponding components and features of strip stock71′ and71″ are identified by the same part numbers as in strip stock71, with the addition of the (′) or (″) designation. Strip stock71′ and71″ differ from each other and from strip stock71by the configuration of notches74,74′, and74″. These different configurations are capable of accommodating different cross-sectional profiles of flanged connectors. Also, notches74′ and74″ are inset further away from the edges of the strip stock71′ and71″ than the location of notch74of strip stock71. This may be desirable to help prevent distortion in the strip stock as it is being formed into the cross-sectional shape showingFIGS. 24 and 28. The strip stock is composed of relatively thin gauge material, typically from 10 to 20 gauge, but can be of other gauge material. In the foregoing description, the notches74,74′, and74″, were described as being cut out or make prior to the forming of the forming of the strip stock into the profile shown inFIGS. 24 and 28. However, such notches can be cut out after the desired profile of the flanged connector is formed, as described above by roll forming and/or bending and/or other well-known techniques. This alternative sequence may be desirable if the particular cross-sectional profile of the flange connector would be such that the strip stock would tend to distort or warp or not otherwise retain the desired shape during forming.

Two of the flanged connectors54, as shown inFIGS. 9,24, and28, are illustrated in face-to-face relationship to each inFIG. 14. Such flange connectors may be retained in face-to-face relationship to each other by use of fasteners, such as self-threading screws extending through the mating flanges102. As noted above, a gasket, a bead of caulk, or other material may be interposed between the mating flanges102to achieve an airtight seal therebetween. Also, rather than using threaded fasteners, the flanged connectors may be retained together by clips, for example, clips similar to clips40shown inFIG. 2. It can be appreciated, through the present invention, duct structure50may be economically manufactured and installed relative to prior art rectangular/square duct structures, including those discussed above.

The flanged connectors54correspond to the T24 flange profile standard established by the Sheet Metal and Air-Conditioning Contractors National Association (SMACNA). Moreover, such connectors are capable of achieving a connector rating from E–J under SMACNA standards. The present invention can be utilized to readily produce other cross-sectional profiles for flanged connectors. Several examples of other profiles are illustrated inFIGS. 15–18. In these figures the part numbers corresponding thereto are identified with the same part numbers as inFIG. 15, but with a letter suffix. As a first example, the flanged connector shown inFIG. 16is also considered to correspond to the SMACNA T24 profile, but with the return section104outward of the hem section106rather than inward as shown inFIG. 15.

FIG. 15illustrates flanged connectors54B, which are similar to flanged connectors54and54A, but without a return section104. This profile corresponds to SMACNA profile T24A.FIGS. 17 and 18depict flange connector profiles54C and54D which also can be manufactured in accordance with the present invention. One manner in which the profile shown inFIG. 17differs from that shown inFIGS. 15 and 16is that the insertion portion82C is offset slightly upwardly at a location254, a distance away from mating flange102C. This offset provides increased structural strength for the insertion flange portion82C and also serves as an abutment for the end of duct82C. The insertion flange section82D, shown inFIG. 18, is also constructed somewhat differently than inFIGS. 14–17. In this regard, an arcuate, inwardly directed ridge256is formed in the insertion flange portion82D. This ridge can serve as a locator for the end of duct52within which the insertion flange is engaged.

FIGS. 29–38illustrate alternative embodiments of insertion flange54. These alternative embodiments differ primarily in the configuration of the re-enforcing sections100E–100N. In these embodiments, like components/features of these flanged connectors are given the same item number as for flanged connector54, but with the addition of an alphabetic suffix E-N. In each of the flanged connector profiles54E–54N, the hem section106E–106N is provided. However, rather than having a return section that is simply folded over on hem section, each of the re-enforcing sections100E–100N are somewhat different in configuration. For example, inFIG. 29, the return section104E actually extends laterally from the distal end of the hem section106E (downwardly, shown inFIG. 29) and then is folded over on itself at258in the direction facing the mating flange. It is to be understood that the folded over portion258could alternatively be folded over to the outside, i.e., away from the mating flange portion102E.

FIGS. 30–38illustrate alternative embodiments of the return section104F–104N. For example inFIG. 30, the return section104F is shown as substantially rectangular or square in cross-section. Whereas, inFIGS. 31,33,36, and37, the return sections104G,1041,104L, and104M, are substantially triangular in shape. InFIG. 32, the return section104H is substantially circular. InFIG. 34, the return flange portion104J is generally rectilinear in shape. InFIG. 35, the return flange portion104K is generally oval, and inFIG. 38, the return flange portion104N is generally hook-shaped, substantially in reverse direction to the return section104K shown inFIG. 35. It is to be appreciated that embodiments other than those inFIGS. 29–38may be utilized for the flanged connector, including the return section of the flanged connector.

FIGS. 39–48illustrate further alternative embodiments of flanged connectors. The flanged connectors54O-54X are similar to flange connectors54E–54N, but with the exception that the hem sections106O-106X extend diagonally from the distal (outer) portion of corresponding mating flanges102O-102X, relative to corresponding mating flanges102E–102N. The hem sections106O-106X may be disposed at other angles than shown inFIGS. 30–48. In addition, rather than being relatively straight, the hem sections106O-106X may be curved, arced, or in other shapes.

FIGS. 49–57illustrate alternative embodiments of flanged connectors, designated as54Y–54AG. As in flanged connector54, such alternative flanged connectors each includes an insertion section, a mating flange and a re-enforcing section. These complements of the flanged connector are given the same part numbers as inFIGS. 9,24, and28, but with the addition of a corresponding letter suffix.

In the flanged connectors54Y–54AD shown inFIGS. 49–54, each includes a short hem section106Y–106AD extending laterally from the distal (outer) edge of the corresponding mating flange102Y–102AD and then a return section104Y–104AD that extends downwardly either substantially parallel to the mating flange or diagonally downwardly and away from the mating flange. Also, each of the flanged connectors54Y–54AD includes a retention leg section260Y–260AD, respectively. Such retention leg sections may be substantially parallel to the corresponding insertion structures82Y–82AD, and help serve to capture or retain the duct52between the insertion section and the leg section. The distal end of the leg sections, shown inFIGS. 49–52, and54, is flared away from insertion section82Y–82AB and82AD, so as to function as a “lead-in” for the duct52when the flanged connector is assembled with the duct.

The flange connectors54AE,54AF, and54AG, as shown inFIGS. 55,56, and57, do not have leg section260. However, in flange connectors54AE and54AF, the insertion sections82AE and82AF are offset similar to that shown inFIG. 17. Also, the distal end portions of the insertion sections82AE and82AF extend or flare diagonally toward the hem section to define a “lead in” since in these embodiments the insertion section is actually exterior to the adjacent end portion of the duct52.

The flanged connector54AG shown inFIG. 57is formed similarly to a T24 profile, about a groove262formed in the mating flange102AG. A bead of caulk or round sealing ring, not shown, or other type of seal, may be placed within the groove262to provide an air tight seal when the flanged connector is installed. As shown inFIG. 57, the end of the duct52includes an outwardly directed end flange264that overlaps a portion of the mating flange102. The end flange264may be readily formed with a die structure, rollers, or other means known in the art.

It will be appreciated that the connectors described above in addition to interconnecting lengths of square or rectangular ducting, can also be used as stiffeners for duct lengths. Such connectors can be manufactured in sizes to closely slideably engage over the duct. Once in place, the connectors can be affixed to the duct wall by any convenient manner, such as with hardware members, for example, threaded screws extending through the insertion sections of the connector and in to the underlying wall of the duct, or by welding.

While preferred embodiments of the invention have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention. In this regard, various configurations and cross-sectional profiles for flange connectors of the present invention have been illustrated and described. These various profiles can be manufactured utilizing the methods of the present invention, beginning with a length of strip stock and forming the desired cross-sectional profile in the strip stock using roll forming bending and other well known techniques. Thereafter, the length of formed strip stock is bent into a square or rectangular configuration corresponding to the cross-sectional shape of the duct being connected together. These methods can be used to form flanged connector rings of other profiles not shown and described herein, for square and rectangular ducts.