AU2009200281B9 - Sealing Mechanism For Ductwork - Google Patents

Abstract

Abstract This invention relates to sealing HVAC ductwork along its joints in order to reduce air leakage, the ductwork able to be sealed by the combination of a gasket and mechanical locking mechanism. II--+-----6 Fig. 2 Fig. 1

Description

Title: 100011 Sealing Mechanism for Ductwork Cross Reference To Related Application [00021 This application claims the benefit of U.S. Provisional Application No. 60/942,412, filed June 6, 2007 which is hereby incorporated by reference in its entirety, the specification of which is attached as an annexure and the drawings of which as Figures 12 to 19. BACKGROUND Field [00031 This technology generally relates to a connection for HVAC ductwork. This technology also specifically relates to a sealing mechanism for HVAC ductwork that reduces air leakage in joints. Description of the Related Art [00041 Traditional ductwork has air leakage at the joints. There has been a need to add a gasket material to the joints so that when the ductwork is connected little leakage occurs. However to be able to add a gasketing material during the manufacturing process the gasketing material would have to have the following properties: 1) Good adhesion to sheet metal; 2) Minimal surface tack; and 3) Short curing time.

[00051 There are numerous materials that have two out of the three qualities listed above but it is very difficult to find one having all three. Therefore, adding a gasketing material to the manufacturing process has been impractical. Typically in ductwork manufacturing it would take three seconds to form the longitudinal seam and then roll the sheet metal duct for shipping. As an example of how traditional gasketing materials would make the manufacturing process difficult one could look at adding a sealant that does not set up quickly. The sealant would have good adhesion to galvanized steel and little surface tack but does not set up quickly. It could take two to three hours or two to three days for the gasketing material to set up or cure. This length of time is not practical as either one would have to wait for each individual sheet to cure or you would have to have some type of stacking systems where the sheets are not touching each other. This would make volume manufacturing in a timely fashion impossible. Additionally, if the material sets up quickly but has too much surface tack it will cause problems in the shipping when the ducts are nested together. [00061 U.S. Patent No, 6,325,389 entitled a Self Sealing Duct/Fitting Connector describes the problems in the prior art with Conventional HVAC systems. It describes the air leakage at the joints with traditional ductwork. The solution in 6,325,389 is a special connector for the ductwork with a sealant. [00071 There is need for sealing the connections between ductwork without having a special fitting that is incorporated in the connections manufactured into the duct work. 2 Summary [00081 The present technology is an attempt at providing a round metal heating ventilation and air conditioning duct for residential or commercial use having a gasket that adheres to the sheet metal and has minimal surface tack. The round metal duct is made from sheet metal and used for the transportation of heated air, air, or cooled air from one location to another. The duct has a male end which is crimped and has a bead on one end of the round duct. The male end is to be inserted into a corresponding female end of another round duct. The duct also has a female end on an opposite end of the round duct to receive a corresponding male end of another round duct. 100091 The gasket may be provided in a first state and can then be cured. The curing process can include an agent and may be complete in 20 minutes or less. Additionally, the gasket may be foamed. [00101 The entire process of making the duct could take 20 minutes or less. 100111 The cured gasket adheres to the duct proximate to an end of the duct. [00121 This invention also provides for the use of ultraviolet light to quicken the curing of the gasketing material. The gasketing material could also be foamed. 3 [00131 The gasketing material can be located: 1) on a leading edge of the male bead; 2) on the inside of the sheet proximate to the female end; 3) on an inside of the female bead; or 4) on an inside of a flared portion of the female end. [00141 This technology is also an attempt at providing a method of manufacturing round sheet metal ducts. Sheet metal is provided. A female end is formed on one end of the sheet metal. The female end is capable of receiving a male end of a different piece of ductwork. A male bead is formed on the male end of the duct. A longitudinal snap locking mechanism on corresponding longitudinal sides of the sheet metal is formed that when the snap locking mechanism is connected a duct is created. [00151 In broad summary, this writing discloses sealing HVAC ductwork along its joints in order to reduce air leakage. The ductwork can be sealed by the combination of a gasket and a mechanical locking mechanism. 10015a] Definitions of the specific embodiments of the invention as claimed herein follow. [0015b] According to a first embodiment of the invention, there is provided a circular cross-sectional sheet metal duct comprising: (a) a tube; (b) a female end on an end of the tube; (c) a male end on an opposite end of the tube extending essentially in the same direction as the tube and the male end having a smaller outer diameter than an inner diameter of the female end of the duct so that the male end can be inserted into a female end on another piece of circular cross-sectional sheet metal duct and when inserted the male end retains the same geometry with the tube as it had prior to being inserted; 4 (d) a longitudinal snap locking mechanism through the length of the circular cross-sectional sheet metal duct that allows the duct to be opened and closed along a longitudinal seam; (e) an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when the circular cross-section sheet-metal duct is joined to another piece of circular cross-sectional sheet metal duct, a sealed joint is created between inner and outer circular surfaces of the two ducts. 10015c] According to a second embodiment of the invention, there is provided in a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the ductwork that allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created and including a bead on the female end of the duct wherein the end that the gasket is located proximate to is the female end and is located on an inside of the female bead. [0015d] According to a third embodiment of the invention, there is provided in a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the ductwork that allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created and including a flared portion on the female end and wherein the end that the gasket is located proximate to is the female end with the gasket located on the inside of the flared portion. 10015e] According to a fourth embodiment of the invention, there is provided in a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the ductwork that 4a allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created; and wherein the gasket is foamed. [0015fJ According to a fifth embodiment of the invention, there is provided in a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the ductwork that allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created; and including a female transverse positioning lock on the female end and a corresponding male transverse positioning lock on the male end. BRIEF DESCRIPTION OF THE DRAWINGS [0016] Fig. 1 is an isometric view of a single section of round ductwork showing a male end of a section of round ductwork. [0017] Fig. 2 is a section view of a male end of the ductwork along section II-II. [0018] Fig. 3 is an isometric view of a single section of round ductwork showing a female end of a section of round ductwork. [Text continues on page 5J 4b [0019] Fig. 4 is a section view of a female end of the ductwork along section IV IV. [0020] Fig. 5 is an isometric view of a single section of round ductwork showing a female end of the ductwork having a bead. [0021] Fig. 6 is a section view of a female end of the ductwork having a bead along section VI-VI. [0022] Fig. 7 is an isometric view of a single section of a ductwork having a flared female end. [0023] Fig. 8 is a section view of a female end of the ductwork having a flared female end along section VIll-Vill. [0024] Fig. 9 is a block diagram of the method for forming ductwork. [0025] Fig. 10 is a transverse positioning lock [0026] Fig. I1 is a second enibodfinent of the lock of Fig. 10 [0027] Fig. I la is a cross sectional view through Fig. I I DETAILED DESCRIPTION OF A PERFERED EMBODIMENT Definitions [0028] "round metal heating ventilation and air conditioning duct for residential or commercial use" - A cylindrical tube used to transport air - this includes spiral, round and oval ducts. [0029] "forming a male crimped end and a female" - creating two ends used to connect ductwork together in the sheet metal. [0030] "forming a longitudinal latching system on the sheet metal duct" creating a mechanism in the sheet metal to connect ends of the duct so that it creates a round metal duct. 5 [0031] "gasket" - any type of sealing material that reduces air leakage between the joints formed in the ductwork. This would include a preformed product that has a tape on it and can be applied to the duct. Loctite nuva sil 5039 is an example of cured gasket material. [0032] "cured" - process by which gasket hardens or toughens or turns into a gasket. Can be cross linking of polymer chains. [0033] "first state" means any pre-cured state. Could be a liquid or other state of polymer or other material prior to reaching its final hardened or cured state as a gasket. (0034] "adheres to the sheet metal" - attaching to the sheet metal. [0035] "minimal surface tack" - When ducts are shipped they are nested against other ducts. The surface tack would be such that the ducts would not stick together and/or would not damage the gasket. This could be accomplished by putting a tape material on one side of the gasket. A gasket with a tape would be a gasket with minimal surface tack. Also an uncovered gasket that does not stick to other ducts would be a gasket with minimal surface tack. 6 (0036] "Ultraviolet" - (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. It is so named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. [0037] "foamed" - injecting some gas or blowing agent causing the gasket to grow creating bubbles in gasket causing the gasket to be more compressible. A gasketing material that has gas bubbles. A Nordson foam mixer could be used to foam the gasketing material. It is desirable to foam the gasket because less gasket material can be used. If it is foamed at 50% then 50% less gasket material is used. [0038] "sealed joint" means a ductwork joint that has less leakage than a ductwork joint without a gasket. [0039] "ductwork" - includes other straight pieces of duct and all types of fittings. [0040] "round metal duct" - a cylindrical tube used to transport air. [00411 "male end"- designed with a projecting part for fitting into a corresponding female part. 7 [0042] "female end"- designed to be hollow or have a groove into which a corresponding male part fits. [0043] "a bead" - an impression formed into sheet metal. [0044] "a longitudinal snap locking mechanism" - something that allows two ends of duct to be joined together without a separate fastener. Examples of this are button lock and a reeves lock. [0045] "sheet metal duct" - Any type of duct work. [0046] "applying an agent" - Using an agent as to aid in the curing. It could be ultraviolet light, radiation, moisture, catalyst or light or anything to help in the curing. [0047] "a female transverse positioning lock" - portion of transverse positioning lock on the female end. [0048] "a male transverse positioning lock" - portion of a transverse positioning lock on the male end. [0049] "transverse positioning lock" - any type of mechanical structure that allows two pieces of ductwork to be rigidly joined together or locked together. 2 - circular duct 4 - crimped end 6 - male bead 8 8 - female end 10 - gasket 12 - leading cdge 14 - female bead 16 - inside of female bead 18 -flared portion Description [0050l Figure I shows a circular duct 2. Male crimped end 4 has a male bead 6. The male crimped end 4 is designed to be inserted into female end 8 of another duct. [0051] Figure 2 shows section 11-II of figure 1. Fast curing gasket 10 is on a leading edge 12 of the male bead 6. The fast curing gasket 10 is proximate to the male end 4. [0052] Figure 3 shows a second embodiment of a circular duct 2. The fast curing gasket 10 is proximate to the female end 8. [0053] Figure 3 shows section IV-IV of figure 3. Fast curing gasket 10 is proximate to female end 8. 9 [0054] Figure 5 shows a third embodiment of a circular duct 2. The female end 8 has a female bead 14. [0055] Figure 6 shows section VI - VI of figure 5. Fast curing gasket 10 is located on an inside of the female bead 16. [00561 Figure 7 shows a fourth embodiment of a circular duct 2. Female end 8 has a flared portion 18. [0057] Figure 8 is a cross section along VIII -VIII of figure 7. Fast curing gasket 10 is located in the flair portion 18. When a male crimped end 4 is inserted into the female end 8, the male crimped end 4 is able to enter without touching the gasket 10 and the gasket 10 seals on a non crimped part of the crimped male end 4. [0058] Figure 9 is a block diagram of the method of making the circular duct. Sheet metal is cut off of a master coil and travels down a conveyor. The sheet travels into a machine where it may or may not get clipped. The optional female bead can be put in the female portion or the flared portion could be created. Optionally at the same time the gasket may be put onto the sheet at that time. Paper or some sort of covering agent might be placed onto the gasket so that it doesn't stick to adjacent pieces of ducts during shipping thereby making it have little surface tack. By doing it this way it gives the fast curing gasket time to cure and if release paper is used it is a nice flat non stick 10 surface at this point. The gasket may travel under ultraviolet lights to cure. Additionally other agents may be used to increase curing time or aid in curing of the gasket. [0059] The sheet will then travel down the conveyor to the roll forming machines where the longitudinal snap locking mechanism is formed and optionally sealant is applied. This can be seen in Application Serial No. i1/739,238 which is hereby incorporated by reference in its entirety. [0060] After the longitudinal snap locking mechanism is formed the male portion is formed by crimping an end of the sheet metal. At this same time the male bead is put on. [0061] At this time applicants believe that the preferred embodiment would add the gasket after the longitudinal snap locking mechanism but prior to male portion being formed. The gasket material is Loctite Nuva Sil 5039 and preferably is foamed when used in this application. It is foamed by a Nordscn Ultra Foam Machine. The foaming helps with the compressibility of the gasket. The compressibility could be determined in a manner of hardness. The hardness could be measured by a durometer and have a hardness less than Shore A 75. Preferably it would have hardness of Shore 00 in the range of 30-50. [0062] A section on the end of the sheet metal may be notched out so that the longitudinal snap locking mechanism stops short of the bead so that it is not crushed I l when the longitudinal snap locking mechanism is formed. The notched out part helps to form a better seal because the male portion can fit better into the female portion. [0063] The male and female sections can be put together and a sealed connection is created without having to take any further steps. When discussing a sealed connection it is meant to refer where minimal air leakage is present or less leakage than when there is no sealant in the connection. [0064] Figure 10 shows a first embodiment of a transverse positioning lock. On the female end 8 of a duct there can be a button lock 20 which in this embodiment is the female transverse positioning lock. The gasket 10 is on an inside of the female end 8 of the duct. The crimped male end 4 has a second bead 22 which in this embodiment is the male transverse positioning lock. The crimped male end 4 fits into the female end so that the second bead 22 slides over buttons lock 20 and locks the pipes together and ensures that the gasket lines up correctly. [0065] Figure 11 shows a second embodiment of a transverse positioning lock. The female end 8 of the duct has a female bead 14. The female end has a cut out 24 on the longitudinal seam. The combination of the female bead 14 and the cut out 24 in this embodiment is the female transverse positioning lock. The longitudinal snap locking mechanism can be seen in Figure I1. A female part 26 of the longitudinal snap locking mechanism is removed up until the female bead 14 to create the cut out 24. The crimped male end 4 has a second bead 22 which in this embodiment is the male transverse positioning lock. The crimped male end 4 fits into the female end so that the 12 second bead 22 slides into female bead 14 and locks the pipes together and ensures that the gasket lines up correctly and creates a proper seal. The cut out 24 allows the duct to radially expand or contract. [00661 Various changes could be made in the above construction and method without departing from the scope of the invention as defined in the claims below. It is intended that all matter contained in the paragraphs above, as shown in the accompanying drawings, shall be interpreted as illustrative and not as a limitation. [00671 The term "comprise" and variants of the term such as "comprises" or "comprising" are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required. [00681 Any reference to publications cited in this specification is not an admission that the disclosures constitute common general knowledge in Australia. 13 CONCEPTS As short summaries, this writing has disclosed at least the following broad concepts: Concept 1. A process for manufacturing a round metal heating ventilation and air conditioning duct for residential or commercial use including providing sheet metal, forming a male crimped end and a female end so that sheet metal duct can connect to other pieces of duct, forming a longitudinal snap locking mechanism on the sheet metal duct the improvement comprising adding a gasket that adheres to the sheet metal and has minimal surface tack. Concept 2. The process as recited in concept I wherein the gasket is applied in a first state and is then cured. Concept 3. The process as recited in concept 2 wherein curing the gasket includes applying an agent. Concept 4. The process as recited in concept 2 wherein the gasket is foamed. Concept 5. The process as recited in concept 2 wherein the gasket is cured in 20 minutes or less. Concept 6. The process as recited in claim I wherein the gasket is placed on a female end. 14 Concept 7. The process as recited in concept I wherein in the male crimped end has a male bead and the fast curing gasket is placed on a leading edge of the male bead. Concept 8. The process as recited in concept I wherein the female end has a female bead and the fast curing gasket is placed on an inside of the female bead. Concept 9. The process as recited in concept I wherein the female end has a flared portion and the fast curing gasket is placed on an inside of the flared portion. Concept 10. The process as recited in concept I wherein the process takes under 20 minutes or less to create a duct. 11. The process as recited in concept I including: (a) creating a female transverse positioning lock on the female end; and (b) creating a male transverse positioning lock on the male end that corresponds to the female transverse positioning lock of another duct to position the connection of the two ducts properly so that the gasket properly works. Concept 12. A duct having a male end and a female end for connection to other ducts the improvement comprising a gasket applied during the manufacturing process that adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created. Concept 13. The duct as recited in concept 12 wherein the'gasket is cured. 15 Concept 14. The duct as recited in concept 12 wherein the end that the gasket is located proximate to is the male end and located on a leading edge of the male bead. Concept 15. The duct as recited in concept 12 wherein the end that the gasket is located proximate to is the female end on an inside wall of the sheet metal duct. Concept 16. The duct as recited in concept 12 including a bead on female end of the duct wherein the end that the gasket is located proximate to is the female end and located on an inside of the female bead. Concept 17. The duct as recited in concept 12 including a flared portion on the female end and wherein the end that the fast curing gasket is located proximate to the female end on an inside of the flared portion. Concept 18. The duct as recited in concept 12 wherein the fast curing gasket is cured using ultraviolet light. Concept 19. The duct as recited in concept 12 wherein the fast curing gasket is foamed. Concept 20. The duct as recited in concept 12 including a female transverse positioning lock on the female end and a corresponding male transverse positioning lock on the male end. 16 6)N0w((UE5 Title: [0001] Sealing Mechanism for Ductwork BACKGROUND OF THE INVENTION Field of the Invention [0002] This invention generally relates to a connection for HVAC ductwork. This invention specifically relates to a sealing and locking mechanism for HVAC ductwork that prevents separation and reduces air leakage. Description of the Related Art [0003] U.S. Patent No. 6,325,389 entitled to Self Sealing Duct/Fitting Connector describes the problems in the prior art with Conventional HVAC systems. One problem is that when the ductwork is put together it does not stay together without being screwed together. Another issue with traditional ductwork is air leakage at the joints. Additionally because the ductwork is not tightly fitted it sometimes is not properly together which causes even greater air leakage. U.S. Patent No. 6,325,389 describes the need for ductwork that "will at least temporarily keep its position during the assembly process before the permanent attachment means is affixed." The solution in 6,325,389 is a special connector for the ductwork.

A?4-).XOP-.C [00041 There is need for sealing the connections between ductwork without having special fitting that is incorporated in the connections manufactured into the duct work. Summary of the Invention [00051 This invention provides for a round metal heating ventilation and air conditioning duct for home or commercial use having a locking mechanism to join the duct to another piece of ductwork. The round metal duct is made from sheet metal and used for the transportation of heated air, air, or cooled air from one location to another. The duct has a male end on one end of the round duct. The male end is to be inserted into a corresponding female end of another round duct. The duct also has a female end on an opposite end of the round duct to receive a corresponding male end of another round duct. The duct also has a female bead horizontally disposed around the circumference of the female end to engage a corresponding male bead horizontally disposed around the circumference of the corresponding male end of another round duct so that when engaged the female bead and the corresponding male bead create a locking mechanism. The other end of the duct has a male bead horizontally disposed around the circumference of the male end to engage a corresponding female bead horizontally disposed around the circumference of the corresponding female end of another round duct so that when engaged the male bead and the corresponding female bead create a locking mechanism. 2 [0006] This invention also provides for ductwork that includes a sealant on the bead. The sealant can be a hot melt or foam sealant. [00071 This invention also provided for a method of manufacturing round self locking sheet metal ducts. Sheet metal is provided. A female end is formed on one end of the sheet metal. The female end is capable of receiving a male end of a different piece of ductwork. A bead is formed on the female end of the duct. A longitudinal snap locking mechanism on corresponding longitudinal sides of the sheet metal is formed so that when the snap locking mechanism is connected a duct is created. A male end is formed on a second end of the sheet metal that is capable of being inserted into a female of different piece of ductwork. BRIEF DESCRIPTION OF THE DRAWINGS [0008] Fig 1. is an isometric view of a female end of round ductwork. [00091 Fig 2. is an isometric view of a male end of round ductwork. [0010] Fig 3 is a cross section view of a male end and female end of the ductwork joined together showing the beads interlocking. 3 [0011] Fig 4 is a cross section view of an alternate embodiment cross section view of a male end and female end of the ductwork joined together showing the beads interlocking. DETAILED DESCRIPTION OF A PERFERED EMBODIEMENT Definitions [0012] "round metal heating ventilation and air conditioning duct for home or commercial use" A cylindrical tube used to transport air - this includes spiral, round and oval ducts. [0013] "a locking mechanism to join the duct to another piece of ductwork" - a mechanism designed so that ductwork fits together and remains together without sheet metal screws and provides a snug fit so that air loss from a joint is limited. [0014] "ductwork" - includes other straight pieces of duct and all types of fittings [0015] "round metal duct" - a cylindrical tube used to transport air 4 [00161 "male end"- designed with a projecting part for fitting into a corresponding female part [0017] "female end"- designed with a hollow or groove into which a corresponding male part fits [0018] "end of the round duct" - an opening of the duct [0019] "an opposite end of the round duct" - the other opening of the duct [0020] "a bead" - an impression formed into sheet metal [0021] "a female bead" - refers to the bead on the female end of the ductwork. This bead could be a raised portion that fits into a depressed portion or vise versa, the use of the adjective female is only meant to convey that the bead is on the female end. The bead can be any shape or size. [0022] "a male bead" - refers to the bead on the male end of the ductwork. This bead could be a depressed portion that receives a raised portion or vise versa, the use of the adjective male is only meant to convey that the bead is on the male end. The bead can be any shape or size. 5 [0023] "horizontally disposed around the circumference of the female end" parallel to the opening on the female end. [0024] "a locking mechanism" - a mechanism designed so that ductwork fits together and remains together without sheet metal screws and provides a snug fit so that air loss from a joint is limited. [0025] "a sealant" - something applied to and affixed to the duct that prevents air leakage. [0026] "a longitudinal snap locking mechanism" - something that allows two ends of duct to be joined together without a separate fastener. Examples of this are button lock and a reeves lock. Description [0027] Figure I shows a female end of round ductwork. There is a bead that is rolled into the sheet metal of the ductwork. The bead is rolled so that its outer circumference of the duct is raised. This bead provides an area on the inside of the duct to apply a sealant. In between the bead and the edge button, locks can be inserted having a protruding portion on the inside of the duct. [0028] Figure 2 shows a male end of round ductwork. The male end of the ductwork has a crimped circumference. There are also three beads rolled into the male 6 end. The beads are rolled so that the outer circumference of the duct is raised. The bead furthest away from the end of the round duct work is often referred to as the stop bead. It is typically used so that when the male end is inserted into the female end it stops the male end from sliding any deeper into the female end. The second and third beads were added so that when the female and male ends are connected, the button locks on the female end engage the space between the second and third bead. When the female and male ends are engaged the sealant will contact the crimped portion of the male end thereby creating a seal. [0029] The beads can be identical. Preferably the male and female bead will be different shapes. The male bead will be smaller. The bead can be on the inside or the outside of the pipe. Instead of the bead sticking up it can stick down. With the bead sticking down it pushes down and can pull the male end in further. [00301 The sealant can be a hot melt or foam. It can be covered with tape or other covering agent. [0031] The sheet metal is cut off of a master coil and travels down a conveyor. The sheet travels into a machine where it may or may not get clipped. The female bead can be put in at the same time and the sealant may be put onto the sheet at that time. Paper or some sort of covering agent might be placed onto the sealant so that it doesn't stick to adjacent pieces of ducts. By doing it this way it gives the sealant time to cure and if release paper is used it is a nice flat surface at this point. 7 [0032] The sheet will then travel down the conveyor to the roll forming machines where the longitudinal snap locking mechanism is formed and optionally sealant is applied. [0033] After the longitudinal snap locking mechanism is formed the male portion is formed by crimping an end of the sheet metal. At this same time the bead is put on. [0034] A section on the end of the sheet metal may be notched out so that the longitudinal snap locking mechanism stops short of the bead so that it is not crushed when the longitudinal snap locking mechanism is formed. The notched out part helps to form a better seal because the male portion can fit better into the female portion. [0035] The male and female sections can be put together and a sealed connection is created without having to take any further steps. When discussing a sealed connection it is meant to refer where minimal air leakage is present or less leakage than when there is no sealant in the connection. [00361 Various changes could be made in the above construction and method without departing from the scope of the invention as defined in the claims below. It is intended that all matter contained in the above description, as shown in the accompanying drawings, shall be interpreted as illustrative and not as a limitation. 8

Claims (10)

1. A circular cross-sectional sheet metal duct comprising: (a) a tube; (b) a female end on an end of the tube; (c) a male end on an opposite end of the tube extending essentially in the same direction as the tube and the male end having a smaller outer diameter than an inner diameter of the female end of the duct so that the male end can be inserted into a female end on another piece of circular cross-sectional sheet metal duct and when inserted the male end retains the same geometry with the tube as it had prior to being inserted; (d) a longitudinal snap locking mechanism through the length of the circular cross sectional sheet metal duct that allows the duct to be opened and closed along a longitudinal seam; (e) an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when the circular cross-section sheet-metal duct is joined to another piece of circular cross sectional sheet metal duct, a sealed joint is created between inner and outer circular surfaces of the two ducts.

2. The duct as recited in claim I wherein the end that the gasket is located proximate to the male end and the gasket is located on a leading edge of the male end.

3. The duct as recited in claim 1 wherein the end that the gasket is located proximate to is the female end on an inside wall of the sheet metal duct.

4. The duct as recited in any one of claims 1 to 3 wherein the gasket is cured using ultraviolet light.

5. The duct as recited in any one of claims I to 3 wherein the uncured gasket applied to the sheet metal during the forming of the sheet metal is applied before the sheet metal is formed into a circular cross-sectional duct.

6. In a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the 18 ductwork that allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created and including a bead on the female end of the duct wherein the end that the gasket is located proximate to is the female end and is located on an inside of the female bead.

7. In a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the ductwork that allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created and including a flared portion on the female end and wherein the end that the gasket is located proximate to is the female end with the gasket located on the inside of the flared portion.

8. In a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the ductwork that allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created; and wherein the gasket is foamed.

9. In a circular cross-sectional sheet metal duct having a male end and a female end for connection to other ducts and a longitudinal snap locking mechanism through the length of the ductwork that allows the duct to be opened and closed along a longitudinal seam, the improvement comprising an uncured gasket applied to the sheet metal during the forming of the sheet metal to form the male end and the female end such that the gasket when cured adheres to the duct and has minimal surface tack and is proximate to one of the ends so that when joined to another piece of duct a sealed joint is created; and including a female transverse positioning lock on the female end and a corresponding male transverse positioning lock on the male end. 19

10. A circular cross sectional sheet metal duct according to claim 1, further comprising: a longitudinally oriented rectangular notch in the longitudinal snap locking mechanism on the female end whereby an end portion of the longitudinal snap locking mechanism is removed from the female end; a female transverse positioning lock; and a male transverse positioning lock; wherein the gasket is positioned so that when the male end of the metal duct is inserted into the female end of an adjacent duct a seal is created and the notch formed in said female end permits unimpeded passage of said male end into said female end. Date: 17 November 2011 20