Metal working – Method of mechanical manufacture – Gas and water specific plumbing component making
Reexamination Certificate
1999-11-16
2001-10-16
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Gas and water specific plumbing component making
C072S084000
Reexamination Certificate
active
06301781
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to Circular and Oval Flanged Rings for connecting oval and circular heating, ventilation and air conditioning (HVAC) ducting sections, from thin gauge Lock Form Quality steel, and a method for spin-forming such Flanged Rings.
BACKGROUND OF THE INVENTION
Joint assemblies are well known for the connection of the ends of adjacent rectangular, circular and oval HVAC duct sections. U.S. Pat. No. 5,129,690 to Meinig recites prior art relating to such assemblies and discloses an apparatus for connecting the ends of oval duct sections without disclosure of the method of making the apparatus; the patent does refer to U.S. Pat. No. 4,516,797 to Meinig which discloses a one-piece flanged ring for connecting the ends of circular duct sections. U.S. Pat. No. 4,516,797 discloses a method for producing the flanged ring by contouring and then bending an elongated sheet-metal strip into an annular shape resulting in a flanged ring having an axial slit and claiming a method for producing a flanged ring characterized as an elongated sheet-metal strip which is contoured and subsequently bent into annular form.
The machine method used to produce such a flanged ring is known to include roll forming. However, roll forming is limited generally to sheet-metal less than 10 gauge with roll forming causing tearing or breaking of sheet-metal in the production of flanged rings from thinner sheet-metal of gauge 10 or greater. Circular flanged rings, produced by roll forming, and thin-walled sheet-metal ducting generally do not have an absolutely circular cross section. The predominate means of manufacturing HVAC ducting is in the form of spiral-seam tubes made up of helical wound sheet-metal strips with the strips interconnected by means of lock seams. The lock seams stand out from the outer duct face.
U.S. Pat. Nos. 4,516,797 and 5,129,690 to Meinig are identified and disclosed in accordance with 37 CFR 1.97.
SUMMARY OF THE INVENTION
An object of this invention is to make, by spinning, forming and trimming, with standard machine tools and machining processes, Circular and Oval Flanged Rings from Lock Form Quality steel of gauge 10 to 20, for the connection of the ends of thin-walled circular and oval sheet-metal tubes or ducting. The present invention is capable of making Flanged Rings that comply to the T24 flange profile of the Sheet Metal and Air-Conditioning Contractors National Association (SMACNA). The method requires LFQ steel strips to be rolled into Flanged Ring Band Stock Strips having Strip First and Second Ends which are butt welded together with a tungsten inert gas process with no filler. A Spinning Die, which is balanced and which has structure means or supporting structural member means, receives the Flanged Ring Band Stock which is secured within the Spinning Die by appropriate means, for example by clamp means. The Spinning Die is rotated by means, for example by a lathe, and standard machine tools are employed to stretch, form and trim the Flanged Ring Band Stock to produce a Circular Flanged Ring for the connection of circular and oval thin gauged pipe or ducting sections.
The preferred embodiment of flanged ring profile described herein constitutes the Sheet Metal and Airconditioning Contractors National Association (SMACNA) standard T24 Flange Profile. The profile disclosed is not limited to the SMACNA T24 profile. However, the method disclosed produces Circular or Oval Flanged Rings while the SMACNA T24 Flange Profile references solely to flanges for the connection of rectangular ducting sections. This disclosure is the only known method of producing the SMACNA T24 Flange Profile for Circular and Oval Flanged Rings from 10 or greater gauge LFQ steel. The SMACNA T24 Flange Profile or cross-section produced by the method described has an Insertion Flange portion which is secured within the Spinning Die by means including clamp means, a Mating Flange portion which is stretched and formed and which meets and matches an opposing mating flange portion, a Hem portion which is formed and a Return Flange.
The Oval Flanged Ring is produced by cutting a Circular Flanged Ring along a diameter to produce approximately equal sized Semi-circular Flanged Ring Portions. Equal length SMACNA T24 Linear Segments of the SMACNA T24 Flange Profile are produced, for instance by roll forming, and are welded to the Semi-circular Flanged Ring Portions to produce the Oval Flanged Ring.
The preferred embodiment of the present disclosed method results in the production of the SMACNA T24 Flange Profile from 10 to 20 gauge Lock Form Quality steel (under 30,000 psi yield/tensile, galvanized G60; however, any metal which can be turned in the following described process and which can be welded may be used for production). The preferred embodiment of the described method requires the preparation of Flanged Ring Band Stock from 3.875″ wide 10 to 20 gauge LFQ steel. The material and material width may be varied as preferred.
An additional object of this invention is the formation of a Circular Flanged Ring which is more nearly circular in cross-section than flanges produced by other means. The truer circular cross-section facilitates the insertion of the Circular Flanged Ring in the spiral-seam tubes comprising most circular and oval HVAC ducting. The method disclosed of making the Circular Flanged Ring enables the use of much thinner gauge steel for the connection of duct section ends and in creating an airtight connection between duct section ends. The Circular Flanged Ring, produced by a spinning process, is more uniformly circular in cross-section than are flanges produced from a roll forming or press operation and more readily sealed, without elaborate gaskets.
REFERENCES:
patent: 2826804 (1958-03-01), Wickwire et al.
patent: 3749425 (1973-07-01), Howland
patent: 4023250 (1977-05-01), Sproul et al.
patent: 4041746 (1977-08-01), Kraft
patent: 4117704 (1978-10-01), Nakache et al.
patent: 4144732 (1979-03-01), Franks et al.
patent: 4170888 (1979-10-01), Golata
patent: 4516797 (1985-05-01), Meinig
patent: 4524595 (1985-06-01), Oda
patent: 4765167 (1988-08-01), Sampson
patent: 5129690 (1992-07-01), Meinig et al.
patent: 5393106 (1995-02-01), Schroeder
patent: 871733 (1961-06-01), None
patent: 1581386 (1980-12-01), None
HVAC Duct Construction Standards, Metal and Flexible, First Edition 1985. Sheet Metal and Air Conditioning Contractors National Association, Inc.; Table 1-12.
Butler Marc W
Christensen O'Connor Johnson Kindnesspllc
Hughes S. Thomas
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