Note: Descriptions are shown in the official language in which they were submitted.
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Background Of The Invention
This invention relates to means for connecting
the ends of a pair of sheet metal duct sections. The in-
vention particularly involves an assembly of the type
including frame members defining flanges located at a duct
end with adjacent frame members joined to each other by
angular corner pieces.
The prior artl particularly Mez U.S. Patent No.
3,712,650 and Arnoldt U.S. Patent Wo. 4,218,079 disclose
flange connections for connecting the ends of rectangular
air conditioning ducts. These arrangements include flange
portions having a horizontal leg portion secured to the
end portion of the duct and a vertical channel-shaped leg
for receiving the arms of an angular corner piece.
In the Mez patent, the angular corner pieces have
arm portions that extend into an opening in the vertical
leg. The arm portions are so dimensioned vertically that
the lower surface of the arms abut the lower wall of the
horizontal flange. With this arrangement, the end of the
duct wall abuts or rests against a surface of the corner
piece arm extending into the channel-shaped opening.
The Arnoldt patent also provides flange portions
having an upstanding channel-shaped leg portion with a
front wall and a rear wall forming a longitudinal opening
therebetween, and a duct receiving leg portion with a top
wall and a bottom wall. A corner piece is insertble in the
longitudinal opening, and provision is also made for gasket
means positioned in the longitudinal opening adjacent the
duct receiving leg bottom wall. The gasket means is
adapted to be positioned between the duct end portion and
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the upper surface of the duct receiving leg bottom wall to
sealingly connect the duct end portion to the frame flange
portion.
In the Mez and Arnoldt arrangements, bolts or the like
are utilized for attaching the corner pieces at one duct end wlth
corner pieces of an adjacent duct end. A suitable clip may then
be snapped in place at the extremities of the adjoining frames at
the respectlve duct ends. The assemblies thus obtained are of
satisfactory strength; however, multiple assembly steps requiring
skill and experience are involved in achieving this assembly.
Siegwart U.S. Patent No. 3,443,601 discloses another
arrangement for joining duct ends. In accordance with this
teaching, frame-like portions are formed as integral parts of a
duct end, and clips or ledges are provided for engagement with
adjacent frame-like portions. The frame-like portions and/or the
clips are designed so that a resilient connection is achieved with
a vlew toward insuring a satisfactory attachment. Although this
arrangement involves fewer assembly steps, the assembly operation
is difficult, and the arrangement is not completely satisfactory
~0 from a strength standpoint.
Summarv of the Invention
The present invention provides a system for connecting
the ends of sheet metal ducts wherein a frame is provided for each
duct end, corner connectors defining perpendicularly extending
arms are associated with the frames, and means are provided to
interconnect the frames of adjacent duct ends, the improvement
whereln the sheet metal used for the ducts is also employed for
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forming said frames~ each said frame speciflcally comprising a
roll-formed section consisting of an integral part of a duct wall,
each said section comprising a first portion extending
perpendicularly outwardly fro~ a duct wall, and a second portion
bent rearwardly into a position opposite an end portion of the
duct wall, the distance between said second portion and said end
portion substantially corresponding to the width of an arm of a
corner connector, the side edges of each such arm being received
in engagement with the respective surfaces of a second portion and
end portion whereby the corner connectors are held in position
relative to a frame, and including retainer means defined by said
second portion for receiving a side edge of an arm for thereby
holding the arm ln position.
In a further aspect the present invention provides a
method for connecting the ends of sheet metal ducts wherein a
frame is provided for each duct end, corner connectors defining
perpendicularly extending arms are asæociated with the frames, and
means are provlded to interconnect the frames of adjacent duct
ends, the improvement comprising the steps of forming each said
frame by roll-forming a section of the duct whereby the frame
comprlses an lntergral part of the sheet metal duct, each sald
roll-formed section comprlslng a flr6t portlon extending
perpendlcularly outwardly from a duct wall, and a second portion
bent rearwardly lnto a position opposite an end portion of the
duct wall, the dlstance between said second portion and said end
portlon substantially corresponding to the width of an arm of a
corner connector, formlng a retainer means ln said second portlon,
a
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introducing the arms of the corner connectors between respective
second portions and end portions whereby the side edges of each
such arm are received in engagement with the respective surfaces
of a said second por~ion and end portion to hold the corner
connectors in position relative to a frame, said retainer means
assisting in the holding by said second portion, and thereafter
fastening the respective connectors together to provide an
assembly .
The invention also involves improvements in corner
connectors wherein each corner connector in the assembly includec
an offset ear formed on the end of each of said arms, and
lncluding a stiffener member extending between the ears on the
end~ of ad~acent connectors mounted on said frames, æaid stiffener
member being held in the space defined by the aid ears and the
ad~acent frame surfaces. This corner connector design enhances
the deslred locking action, while at the same tlme, providing a
convenient arrangement for assembly. The corner connectors also
provide means for minlmlzing gaps or openings ln the joint area.
Flnally, the connectors preferably include convenlent attaching
means for stiffeners when such additlonal elements are desirable.
In a further aspect the present lnventlon provldes a
system for connectlng the ends of sheet metal ducts wherein a
frame is provided for each duct end, corner connectors defining
perpendicularly extending arms are associated with the frames, and
means are provided to interconnect the frames of adjacent duct
ends, the improvement wherein each said frame comprises a first
portion extending perpendlcularly outwardly from a duct wall, and
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a second portion bent rearwardly into a position opposite an end
portion of the duct wall, a flrst channel formed in said second
portion for receiving a side edge of an arm, and a second channel
formed in said end portion of the duct wall for rec~iving the
opposite side edge of an arm, the distance between said channels
of said second portion and said end portion substantially
corresponding to the width of an arm of a corner connector, the
side edges of each such arm being received in engagement with the
respective bottom surface~ of said channels whereby the corner
connectors are held in position relative to a frame.
The present invention also provides a method for
connectlng the ends of sheet metal ducts of the type having a
frame located at each duct end, corner connectors defining
perpendlcularly extending arms associated with the frames, and
means for lnterconnecting the frames of adjacent duct ends, the
improvement comprising the steps of roll-forming each said frame
to provide a first frame portion adapted to extend perpendicularly
outwardly from a duct wall when the frame ls located in position,
a second portion bent rearwardly relatlve to sald first portion,
and a thlrd portion opposite said second portion, the distance
between said second portion and said third portion substantially
corresponding to the width of an arm of a corner connector,
forming a retalner in said second portion of said frame, attaching
said corner connectors to said frames by locating one side edge of
each arm in the space between sald second and third portions and
driving the opposite side edge of that arm into said space whereby
the respectlve side edges of each such arm are received ln
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engagement with the respective surfa~es of said second portion and
said third portion, said retainer means assisting in the holding
by said second portion whereby the corner connectors are held in
position relative to a frame~
When assembled according to the methods of the present
invention, the resulting duct assembly is characterized by great
strength so that a highly reliab].e assembly operation can be
achieved with minimum expense and effort. If desired, a clip can
be located around the adjacent frames of adjoining ducts. Gasket
material may also be located between adjacent frames without
difficulty.
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~rief Description Of The Drawings
Figure 1 is a fragmentary perspective view of a
duct assembly characterized by the features of this inven-
tion;
Figure 2 is an enlarged fragmentary, cross-
sectional view of a duct joint taken about the line 2-2 of
Figure l;
Figure 3 is a plan view of a corner connector of
the type preferably used in conjunction with the duct joint
of this invention;
Figure 4 is a fragmentary plan view of a duct
blank especially designed for the practice of the inven-
tion;
Figure 5 is a plan view of a corner connector
structure including improved features;
Figure 6 is an elevational view of the connector
shown in Figure 5 taken from one side of the connector;
Figure 7 is a elevational view of the connector
of Figure 5 taken from another side of the connector;
Figure 8 is a horizontal, sectional view taken
about the line 8-8 of Figure 5;
Fiqure 9 is a cross-sectional view taken about
the line 9-9 of Figure S; and,
Figure 10 is a cross-sectional view taken about
the line 10-10 of Figure 5;
Figure 11 is a fragmentary, sectional view illus-
trating the corner connector of Figure 5 as part of a duct
joint;
Figure 12 is a fragmentary side elevational view
of the duct joint of Figure 11;
Figure 13 is a cross-sectional view taken about
the line 13-13 of Figure 11;
Figure 14 is a cross-sectional view illustrating
a stiffener design taken about the line 14-14 of Figure 11;
and,
Figure 15 is a fragmentary, cross-sectional view
illustrating the stiffener design.
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_tailed Description Of the Invention
Figure 1 illustrates a series of ducts 10 of the
type typically used for heating and ventilating purposes.
The ducts are assembled by means of duct end joining means
12. Typically, such joining means are used with relatively
large ducts of the type employed for commercial and indus-
trial applications. Where the span between ducts is rela-
tively long, stiffeners may be employed intemediate the
duct joining means.
Figure 4 illustrates a duct blank 14 of the type
contemplated for use in the practice of the invention.
This blank is adapted to be folded along the lines 1~ to
achieve the rectangular configuration of Figure 1. The
respective ends 18 and 20 of the blank are adapted to be
formed in a manner to be described whereby the end of a
duct formed from one blank can be joined with the end of
another duct.
Figure 2 illustrates in cross section the roll-
formed shape of the end 18 of one duct, and the roll-formed
shape of the end 20 of an adjacent duct. The roll-forming
operation for achieving this configuration may be conducted
on known equipment, for example equipment of the type
described in Ryan Patent No. 4,045,989.
Each of the formed ends 18 and 20 comprise an up-
turned portion 22 extending perpendicularly from the duct
wall. A second portion 24 is bent rearwardly whereby this
portion 24 extends opposite a portion of the duct wall. A
return portion 25 is also provided, and a bead 28 is formed
at the same time.
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The cornbination of the outwardly extending por-
tion 22 and the rearwardly extending portion 24 comprises a
frame formed integrally with the duct wall. In a preferred
form of the invention, a channel 30 is formed between the
bead 28 and the portion 22, and a similar channel 32 is
formed in the duct wall opposite the channel 30. A corner
connector 34 defines edges 36 and 38 which can be received
by the respective channels.
The corner connector 34 is shown in greater de-
tail in Figure 3. The corner connector peferably comprises
a cast or forged member which rnay be Machined to achieve
the edges 36 and 38. This member is preferably of a rela-
tively stiff metal whereas the sheet ~etal forming the duct
and integral frame is peferably of relatively resilient
material. With this combination, the corner connector is
adapted to be snapped into place by locating the edge 38 of
the corner connector in channel 30 and by then driving the
edge 36 toward portion 22 for setting of the edge 36 in
channel 32.
As shown in Figure 3, the corner connector 34
consists of perpendicularly extending arms. In the as-
sembly illustrated in Figure 1, it will be appreciated that
one corner connector will span the separation between adja-
cent frames of a duct. An individual assembling the ducts
will simply snap four corner connectors in place for a giv-
en duct end, and this operation can be achieved manually
without the need for any tools. Where equipment of the
type described in the aforementioned Ryan patent is uti-
lized, the integral frames may be automatically formed, and
the duct readily bent to the desired rectangular configura-
tion. Accordingly, neither highly sophisticated labor nor
great effort is required for achieving the desired assembly
of the corner connectors and fralnes.
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When assembling one duct with another, the re-
spective frames and associated corner connectors are
brought together, and a bolt 40 or other suitable fastener
may be employed for achieving the desired connection. A
bolt hole 46 is provided in each corner connector, and
additional holes 48 are located adjacent the ends of the
connector arms so that additional fasteners may be employed
which in this case will extend through the walls of the
frames. Prior to completion of this connection, a gasket
42 may be located between the respective frame portions for
conventional purposes.
A clip 44 is shown in engagement with the frame
portions of adjacent ducts. This clip may be designed to
snap into place and will serve to provide a smooth-exposed
joint. The clip may also function to strengthen the joint.
Figures 5 through 13 illustrate a corner connect-
or 50 of a particularly preferred design. This connector
also includes perpendicularly extending arms, and the con-
nector is adapted to be included as part of a duct joint.
As shown in Figures 11 through 13, the connector is partic-
ularly adapted for use in association with ducts of the
type previously described which include roll-formed ends 18
and 20.
Each of the corner connectors 50 defines an em-
bossed area 52 on an inside facing surface. The inwardly
extending embossed area of one connector will engage the
corresponding area of an adjacent connector when a duct
joint is formed (see Figure 12). When the bolt 54 is
tightened, the engagement of the embossed areas results in
the application of thrust forces by the arms of the connec-
tor, and these thrust forces act to press the respective
ends 18 and 20 together. The thrust forces are applied by
the respective pairs of arms at each corner of the assem-
bled ducts to provide a highly satisfactory locking action.
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Each o~ the connectors 50 also includes outer
edges 56 on its arms. These edges extend angularly out-
wardly from the arms, and the edges are adapted to be re-
ceived within the channels formed by the duct ends as shown
in Figure 13. In practice, the outer edges 56 of the con-
nectors are first positioned in channels 30 in an inclined
attitude, and the connectors are then pivoted so that the
inner edges 58 will snap into place within channels 32.
The angular configuration of the edges 56 and the respec-
tive dimensions of the parts are such that the material
bead 28 will yield as the connectors are snapped into place
thereby providing very secure holding forces for the con-
nectors relative to the duct ends.
The connectors 50 are also characterized by an
inside corner flange 60. This corner flange will serve to
cover the opening which is defined at each corner 62 of
each duct. These openings or gaps necessarily result when
the duct blank is cut to provide the portions to be roll-
formed into duct ends 18 and 20. By designing the corner
connector in this fashion, the ou-ward flow of air from
within the ducts is significantly minimized.
Each of the arms of the connectors 50 is provided
with an offset ear 64 which may be employed for retainng
stiffener members over-lying the surfaces of duct ends 18
and 20. A stiffner 66 is shown in Figure 11 as an example
of the type of member which could be provided, this stif-
fener comprising a strip of spring steel or the like which
can be engaged at its ends beneath the ears 64. At its
sides the stiffener is gripped between channels 30 and 32.
Particularly if the stiffener is of sufficient length it
will assume a corrugated or serpentine configuration as
shown in Figure 15, that is, bends will be present along
its length and this will add to the stiffening capability.
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The particular stiffener shown is an example only
of form suitable for the roll-formed cross-section, and it
will be appreciated that other designs could be utilized.
In this particular embodiment shown, the ends of the stif-
fener are advantageously slid beneath ears 64 before at-
ttachment of the clips 44.
In addition to the improvements in duct and con-
nector design which have been described, the invention also
involves the combination which generally provides for the
roll-forming of an integral frame at a duct end. The roll-
forming operation is such that a retaining means is automa-
tically provided for a corner connector whereby the corner
connector can be quickly assembled with the frame. The
subsequent bolting of one duct end to another and the addi-
tion of clips and gaskets can then be conveniently accom-
plished~ The simplified operation results in a duct assem-
bly of highly satisfactory strength whereby the combination
is particularly suitable for use for commercial and indus-
trial applications.
It will be understood that various changes and
modifications may be made in a system of the type described
which provide the characteristics of the invention without
departiny from the spirit thereof particularly as defined
in the following claims.
