Metal working – Method of mechanical manufacture – Gas and water specific plumbing component making
Reexamination Certificate
1999-08-16
2001-10-09
Aida-Rosenbaum, I (Department: 3726)
Metal working
Method of mechanical manufacture
Gas and water specific plumbing component making
C029S525010, C138SDIG004
Reexamination Certificate
active
06298555
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of making a duct from a flat board utilizing a grip flange. In particular, the board from which the duct is made is a rigid or a semi-rigid material capable of undergoing at least a small amount of compressive deformation and the grip flange is mounted to the board for assembly of the duct without the utilization of adhesives or welding.
2. Prior Art
A board having these qualities has recently been produced for use in forming thermally insulating ducts such as are employed for heating, ventilation and air conditioning. It consists of a rigid foamed plastics material, for example, a closed cell expanded phenolic foam, although other open or closed cell expanded foam materials such as polyurethanes could be used. As produced, the expanded plastics material is in the form of a planar board having a metallic foil, for example of aluminum, bonded to each major surface. Ducting, typically of rectangular cross section, may be produced therefrom.
As opposed to conventional ducts formed of metal sheet, the product is light, with good thermal insulating properties, and often sufficiently rigid per se for the intended use (although further strengthening measures can be taken in this respect if necessary, for example when requiring long unsupported spans, large cross-sectional areas, or significant differential pressures between interior and exterior). However, a problem arises as to how to firmly and efficiently couple together edge portions of the planar board to form ducting of a polygonal cross-section and how to couple a length of duct so formed either to a further length thereof, or to ancillary equipment such as a fan.
SUMMARY OF THE INVENTION
The present invention is a unique method of making a duct of polygonal cross-section from a planar board including the steps of cutting the board so that it may be bent into a duct of the required polygonal cross-section, mounting a grip flange to the opposing edge portions of the board, each of said grip flanges comprising a two-piece grip flange comprising interlocking snap-together male and female sections with cross-sectional shapes similar to an L and an F, respectively, which when snapped together form a panel insertion channel to both frictional engage an edge portion of said board and clamp said edge portion through forcible deformation of the edge portion whereby a permanent and secure attachment to the edge portion of the board is provided without the use of any hardware, adhesive or welding, and coupling together the grip flanges provided on the opposing edge portions of the board.
In particular, the grip flange for assembly to the edge portion of the board comprises first and second elongate portions, said first portion comprising a first elongate web, and a sole elongate second web extending from one side of the first web to provide a member of L-shaped cross-section, and said second portion comprising third and fourth elongate webs providing an L-shaped cross-section, and a fifth web extending from the third web in spaced relation to, and generally parallel to, the fourth web to form with the fourth web an insertion channel for reception of at least a free elongate edge portion of the second web, the insertion channel and the said free portion being adapted for frictional engagement.
Preferably the fifth web is adapted for providing the frictional engagement with the free portion. The frictional engagement may be provided by raised portions on the interior surface of the channel and/or on the free portion, and preferably on the surfaces of both parts where one overlies the other when the two portions are assembled about the board edge. In a preferred embodiment the frictional engagement is provided by elongate ribbing on at least one surface of the free portion and the corresponding internal surface(s) of the insertion channel, and preferably this ribbing is formed on the fifth web.
Preferably the second web has a width substantially equal to, or slightly less than, the thickness of the board for which the grip flange system is intended, and the fourth web has a width which is at least substantially equal to the board thickness. Advantageously both these conditions apply, so that the two webs substantially co-extend across the bottom of the U-shaped channel formed by the assembled first and second flange portions.
Preferably either or (advantageously) both the first and third web are adapted for frictional engagement and/or deformation of the board, such as by being provided with raised portions. In a preferred embodiment, these raised portions are in the form of at least one longitudinal rib internally of the L-shaped cross-section, but other means, for example the provisions of inwardly projecting tangs which deform or pierce the metal foil, are possible.
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patent: 5644878 (1997-07-01), Wehrmann
Aida-Rosenbaum I
Al International SRL
Koda & Androlia
Nguyen T.
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