Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
_. a ,. .
CA 02571165 2009-02-13
NOVEL MUNTIN BAR ASSEMBLIES
TECHNICAL FIELD
[01] The present invention pertains to glazing assemblies and more
particularly to glazing
assemblies incorporating muntin bar assemblies.
BACKGROUND
[02] Muntin grids, or lattices, are often added to glazing assemblies, in
order to increase the
aesthetic appeal of the glazing assemblies. Muntin grids typically consist of
lineal elements, or muntin bars, that subdivide a glazed opening created by a
perimeter
frame work assembly, particularly in the context of windows and doors.
Insulated
glass type glazing assemblies, or insulating glass units, often incorporate
the muntin
bars between two glass panes which are spaced apart by a spacer frame to which
the
muntin bars are attached. The muntin bars may be attached to the spacer frame
by
components called muntin keepers, which are cross-connecting pieces having one
portion designed for attachment to the end of a muntin bar and another portion
for
attachment to the spacer frame; alternately muntin bar ends may be embedded
within a
sealing material extending along the inside perimeter of the spacer frame
between the glass
panes.
[03] The secure attachment of muntin bars to spacer frames, before and after
completing the
assembly of insulating glass units, is important in preventing costly re-work
along the
assembly line, and to maintaining an aesthetically pleasing appearance of the
final product assembled into a door or window that is subject to environmental
loading.
Furthermore, it is desirable that muntin bar attachment not compromise the
integrity of
other elements of the insulating glass (IG) assembly/unit, for example, that
of the spacer
frame or of the seal between the glass panes and the spacer frame, nor
interfere with, or
reduce the efficiency of, other processes required for IG unit production.
Thus, there is a
need for new methods and components providing for the secure attachment of
muntin bars
to spacer frames without compromising the integrity of IG unit components, or
the
efficiency of assembly processes.
SUMMARY
[04] Accordingly, in one aspect there is provided a muntin bar assembly,
comprising:
a spacer including a surface;
a muntin bar;
1
CA 02571165 2009-02-13
at least one muntin bar keeper including a base and at least one engaging
element,
the at least one engaging element extending out from the base and holding the
muntin bar
in a fixed relation with the spacer, and the base and the at least one
engaging element
being integrally formed from sheet metal; and
at least one weld joint formed between the base of the at least one keeper and
the
spacer surface.
[04a] According to another aspect there is provided a method for preparing a
muntin bar
assembly, the method comprising:
forming at least one muntin bar keeper from sheet metal such that at least one
engaging element of each of the at least one keeper extends integrally with,
and out from,
a corresponding base of each of the at least one keeper;
welding the base of each of the at least one muntin bar keeper to a spacer;
and
attaching a muntin bar to the engaging element of each of the at least one
keeper.
[04b] According to yet another aspect there is provided a component for
holding a muntin bar in
a fixed relation with a spacer within an insulating glass assembly, the
component
comprising:
at least one engaging element to hold the muntin bar; and
a base supporting the engaging element and including an area being offset from
the engaging element to accommodate welding of the base to a surface of the
spacer,
wherein the base is free of any spacer-engaging protrusions.
[04c] According to yet another aspect there is provided a component for
holding a muntin bar in
a fixed relation with a spacer within an insulating glass assembly, the
component
comprising:
at least one engaging element to hold the muntin bar; and
a base supporting the engaging element and including a weld projection.
[04d] According to still yet another aspect there is provided an insulating
glass assembly,
comprising:
a pair of glass panes;
a spacer separating the glass panes from one another and including a surface
disposed therebetween;
a muntin bar disposed between the glass panes;
at least one muntin bar keeper including a base and at least one engaging
element,
the at least one engaging element extending out from the base and holding the
muntin bar
2
. i . . ... . . .L. .. . . . . . .... _ .. ... . . .
CA 02571165 2009-02-13
i
in a fixed relation with the spacer, and the base and the at least one
engaging element
being integrally formed from sheet metal; and
at least one weld joint formed between the base of the at least one keeper and
the
spacer surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[05] The following drawings are illustrative of particular embodiments of the
present invention
and therefore do not limit the scope of the invention. The drawings are not to
scale (unless
so stated) and are intended for use in conjunction with the explanations in
the following
detailed description. Embodiments of the present invention will hereinafter be
described in
conjunction with the appended drawings, wherein like numerals denote like
elements.
[06] Figure 1 is a perspective view, including a cut-away section, of an
exemplary IG assembly.
[07] Figure 2A is an exploded view of a portion of the assembly shown in
Figure 1, according to
some embodiments of the present invention.
[08] Figure 2B is a perspective view of the keeper shown in Figure 2A.
[09] Figure 2C is an end view of a portion of the portion of the assembly
shown in Figure 2A,
according to some embodiments of the present invention.
[010] Figure 2D is an end view of the keeper shown in Figure 2B.
[011] Figure 3 is a cross-section view through section A-A of Figure 1,
according to some
embodiments of the present invention.
[012] Figure 4 is a flow chart outlining some assembly methods of the present
invention.
[013] Figures 5A-B are schematics showing alternative welding process set ups,
according to
some embodiments of the present invention.
[014] Figure 5C is a plot of an exemplary resistance welding schedule,
according to some
embodiments of the present invention.
[015] Figure 6 is a schematic showing a cohesive group of keepers, according
to some
embodiments of the present invention.
[016] Figure 7A is a perspective view of an alternate embodiment of a muntin
bar keeper.
[017] Figures 7B-C are a perspective view and an end view, respectively of
another alternate
embodiment of a muntin bar keeper.
2a
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
[18] Figure 7D is a cross-section view, for example, through section line A-A
of Figure 1,
according to some alternate embodiments of the present invention.
[19] Figure 8A is a perspective view of yet another embodiment of a muntin bar
keeper.
[20] Figure 8B is a cross-section view, for example, through section line A-A
of Figure 1,
according to additional alternate embodiments of the present invention.
[21] Figure 9 is a cross-section view, for example, through section line A-A
of Figure 1,
according to yet further embodiments of the present invention.
DETAILED DESCRIPTION
[22] The following detailed description is exemplary in nature and is not
intended to limit the
scope, applicability, or configuration of the invention in any way. Rather,
the following
description provides practical illustrations for implementing exemplary
embodiments of
the present invention.
[23] Figure 1 is a perspective view, including a cut-away section, of an
exemplary IG
assembly 20. Figure 1 illustrates IG assembly 20 including a pair of glass
panes 22
spaced apart by sides 35 (Figures 2A,C) of a spacer frame 24, to which panes
22 are
fixed, for example, by an adhesive, which may double as a sealant; a muntin
bar grid 40
is shown disposed in the space between panes 22, being held in a fixed
relation with
spacer frame 24. Figure 1 further illustrates spacer frame 24 being formed by
a spacer 30
which includes a wall 32 defining a lumen or channel 34 in which a plurality
of desiccant
granules 36 are disposed; such granules 36 may be useful for preventing
condensation
between panes 22. According to the illustrated embodiment, grid 40 includes a
relatively
long muntin bar 41 extending from a first end 411 to a second end 412, and two
shorter
bars 43 each extending from a first end 431 to a second end 432; ends 411, 412
of longer
muntin bar 41 and ends 431 of shorter muntin bars 43 are joined to
corresponding sides
of spacer frame, while ends 432 of shorter muntin bars 43 are joined to longer
muntin bar
41. It should be noted that the scope of the present invention is not limited
by any
particular number and/or arrangement of muntin bars.
[24] Figure 2A is an exploded view of a portion of assembly 20, according to
some
embodiments of the present invention. Figure 2A illustrates a muntin bar
keeper 220
joined to spacer 30 along a surface 104 thereof; keeper 220 includes a base
26, for joining
3
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
keeper 220 to spacer 30, and an engaging element 200 extending out from base
26,
which, when inserted, at end 411, within a center rectangular portion 302
formed by a
wall 401 of muntin bar 41, holds muntin bar 41 in fixed relation with spacer
30. (It
should be noted that Figure 2A may also be illustrative of end 412 of muntin
bar 41 as
well as end 431 of muntin bar 43.) Muntin bars 41, 43, as well as others
described
herein, may be formed from aluminum, stainless steel, or any other suitable
metal, or
from plastics or composites, being either hollow, as described herein, or
solid, according
to alternate embodiments.
[25] Figure 2B is a perspective view of keeper 220, and Figure 2C is an end
view of the
portion shown in Figure 2A including keeper 220 and spacer 30. According to
the
illustrated embodiment, base 26 of keeper 220 extends alongside spacer surface
104 and
is attached thereto by two weld joints 25, which are disposed on either side
of engaging
element 200 on tab portions 260 of base 26. With reference to the embodiment
illustrated
in Figure 2C, it may be appreciated that the attachment of keeper 220 to
spacer 30, by
joints 25, does not compromise the integrity of spacer wal132, which could be
compromised, for example, by a piercing of a protruding portion of another
type of
keeper through wall 32 at surface 104 - such piercing could allow desiccant
granules 36
(Figure 1) to leak out from lumen 34. Neither does the attachment of keeper
220,
according to the illustrated embodiment, compromise the integrity of bonds
between
panes 22 and spacer frame 24 (Figure 1), that extend alongside sides 35 of
spacer 30.
Furthermore, according to preferred embodiments, attachment of keepers via
welding can
save a processing step required to create features in a spacer for the
engagement of
mating keeper features, for example, a forming of one or more holes through
the spacer
wall to engage keeper protrusions. However, it should be noted that alternate
embodiments of the present invention may employ mating keeper and spacer
features.
[26] Figure 2B further illustrates an optional weld projection 224 as a recess
in an upper
surface of each of tab portions 260. Figure 2D is an end view of keeper 220
showing
weld projection 224 projecting from a lower surface of tab portion. Weld
projection 224
may facilitate resistance welding, according to some embodiments that will be
described
below. An alternate embodiment of a weld projection is formed by a plurality
of
relatively smaller recessed surfaces. One or more weld projections included in
certain
4
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
embodiments of the present invention should not be construed as interlocking
features;
keepers, according to certain preferred embodiments of the present invention,
are free of
any spacer-engaging protrusions that need to be interlocked with a feature of
the spacer in
order to complete a junction between the keeper and the spacer.
[27] Figures 2A-C further illustrate engaging element 200 of keeper 220
including a pair of
opposing legs 226 in an A-frame structure to provide for a press fit, a
friction fit, or an
interference fit within an interior portion of a muntin bar, for example,
within wall 401 of
muntin bar 41. According to the illustrated embodiment, legs 226 act like a
spring,
bending toward one another, to allow for insertion into muntin bar 41, and
pressing
outward against muntin bar wall 401 once inserted. Each leg 226 is shown to
include an
extension 206, folding outward and over toward base 26, in order to facilitate
the
insertion into muntin bar 41 and to provide a contact surface between engaging
element
200 and an inner surface of wall 401. According to exemplary embodiments of
the
present invention, keeper 220 is formed by a sheet metal stamping process, for
example,
from stainless steel sheet metal having a thickness from approximately 0.005
inch to
approximately 0.020 inch. It should be noted that the present invention is not
limited to
exemplary configurations of engaging elements described herein, and that
alternate
embodiments include any type of friction fitting or interlocking member,
either male, for
example, as in the illustrated embodiments, or female, to alternately fit
about an exterior
surface of a muntin bar.
[28] Figure 3 is a cross-section view through section A-A of Figure 1
illustrating the fit of
engaging member 200 of keeper 220 within wall 401 of muntin bar 41, according
to some
embodiments of the present invention. It may be appreciated, with reference to
Figure 3,
that the fit of engaging member 200 within center rectangular portion 302 of
bar 41
provides a stable attachment to hold bar 41 in the fixed relation with spacer
30. With
reference to Figure 3, in conjunction with Figure 1, it may further be
appreciated that the
contoured profile of bar 41, as well as that of bars 43, effectively hides
keeper 220 from
view when bars 41 and 43 are attached to spacer 30, as shown in Figure 1. It
should be
noted that, in some configurations of the present invention, more than one
keeper, of any
embodiment described herein, may be used to hold a single end of a muntin bar,
for
example, a muntin bar having a relatively large profile cross-section.
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
[29] Figure 4 is a flow chart outlining some assembly methods of the present
invention.
According to the flow chart of Figure 4, an initial assembly step 501, in
which a spacer is
prepared, is followed by a step 503, in which one or more weld keepers are
welded to the
spacer. Following step 503, one or more muntin bars are attached to the
spacer, per step
509, for example by insertion of a keeper, which is welded to the spacer, into
an end of
the muntin bar, as previously described. Additional spacer prep, per step 507,
may be
necessary, according to some embodiments, prior to attaching muntin bar(s).
[30] Spacers for IG assemblies are typically formed from lineal sections of
rolled aluminum or
stainless steel that are cut to length, according to a specified dimension of
the
corresponding IG unit, and then bent into a frame for subsequent glazing.
According to
some assembly methods of the present invention, spacer lineal sections are cut
to length,
per step 501, and then one or more keepers are welded, per step 503, to the
spacer, in
lineal form, for example, as illustrated in the schematic of Figure 5A.
According to
Figure 5A, spacer 30 has been cut to length, for example, appropriate for
assembly 20
shown in Figure 1, keepers 220 have been positioned for muntin bar attachment,
and
keepers 220 and spacer 30 have been directed, per arrow C, so that each keeper
passes
beneath a welding station 650 for welding to spacer 30. However, according to
alternate
embodiments, welding station 650 may move to weld each keeper 220 to spacer
30, while
spacer 30 is held stationary. Welding station 650 is shown to include two weld
heads 65
which may either simultaneously or sequentially weld tab portions 260 (Figure
2A-B) of
keepers 220 to spacer 30; according to alternate embodiments, a welding
station includes
a single weld head. It should be noted that any number of weld joints may be
employed
to join a keeper to a spacer without departing from the spirit and scope of
the present
invention. Figure 5A further illustrates, with dashed lines, optional
additional welding
stations 650, employed in order to increase productivity by welding more than
one keeper
at a time. Once keepers 220 have been welded to spacer 30, spacer can be bent
into
shape to form a frame, for example frame 24 of Figure 1, per step 507 of
Figure 4, and
then muntin bars are attached thereto, per step 509.
[31] According to some alternate assembly methods of the present invention,
the spacer prep
of step 501 fiuther includes bending the spacer into a frame so that the one
or more
keepers are welded to the spacer when it is in frame form, for example, as is
illustrated in
6
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
the schematic of Figure 5B. According to Figure 5B, welding station 650 is
held in a
fixed position and spacer frame 24 is rotated, per arrow B, to bring each
interior side of
spacer frame 24 into position with respect to welding station 650 for the
welding of each
keeper 220 to a respective side. However, according to alternate embodiments,
weld
station 650 moves to each interior side of spacer frame 24, which is held
stationary, in
order to weld each keeper 220 to the respective side; and, according to
additional
alternate embodiments, multiple welding stations may be provided, so that more
that one
keeper 220 at a time may be welded to spacer frame 24. Figure 5B further
illustrates
ends 231, 232 of spacer uncoupled, leaving a gap 240, which facilitates
flexing of frame
24 for subsequent attachment of muntin bars, per step 509 of Figure 4, and
which is
closed, by coupling of ends 231, 232 together, following muntin bar
attachment.
However, frame 24 may flex enough without gap 240, so that, according to an
alternate
method, muntin bar attachment follows the coupling of spacer ends 231, 232.
[32] According to some preferred embodiments of the present invention,
resistance-type
welding is used to join keepers to spacers. Those skilled in the art of
resistance welding
understand that resistance welding uses the application of electric current
and mechanical
pressure to create a weld between two pieces of metal, thus, according to the
preferred
embodiments, weld heads 65 are electrodes which conduct an electric current to
keeper
base 26 and spacer wal132, while applying pressure to force base 26 and wa1132
together
into intimate contact. A welding cycle first develops sufficient heat to raise
a small
volume of metal to the molten state, while pressure is applied; the metal then
cools, while
still under pressure, until it has adequate strength to hold the parts
together. The current
density and pressure must be sufficient to produce a weld nugget, but not so
high as to
expel molten metal from the weld zone. Figure SC is a plot of an exemplary
schedule for
a resistance welding cycle to weld a stainless steel muntin bar keeper, for
example, along
base 26 of keeper 220, to a stainless steel spacer, for example spacer 30. The
illustrated
exemplary weld schedule is suitable for a holding force of approximately 6
pounds and a
keeper wall thickness in the range of approximately 0.005 inch to
approximately 0.010
inch. Welding per the illustrated schedule may be facilitated by weld
projection 224
(Figure 2B), which creates a receptacle for weld electrode 65, thereby
providing a
reduced and controlled surface area between keeper base 26 and spacer surface
104, for a
7
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
greater current density, so that less current is required for welding.
According to the
exemplary welding schedule illustrated in Figure 5, weld head 65 applies
pressure for 250
milliseconds, prior to ramping up a current to approximately 950 Amps, over
approximately 1 milliseconds. The 950 Amp current is applied for approximately
5
milliseconds before dropping back to zero, and the force is held for another
150
milliseconds after the drop. It should be noted that the scope of the present
invention is
not limited by a particular welding schedule, since alternative resistance
welding
schedules may be tailored according to alternate materials and geometries of
spacers and
keepers within the scope of the present invention. Furthermore, although
resistance
welding is preferred, any other type of welding known to those skilled in the
art may be
employed, without departing from the spirit and scope of the present
invention, examples
of which include, without limitation, MIG (Gas Metal Arc Welding) welding, TIG
welding (Gas Tungsten Arc Welding), and mini-plasma welding.
[33] Some assembly methods of the present invention further include a step to
separate each
keeper 220 from a cohesive group, for example, group 600 shown in Figure 6,
prior to
placing each keeper 220 for welding to spacer 30. According to the illustrated
embodiment, keepers 220 are held together in group 600 by a continuity of base
26,
which includes severing points 62 disposed between each engagement element 200
and
group 600 is formed in a coil so that engagement elements 200 face inward; the
coil may
be unrolled in order to dispense keepers 220, for example, via a hitch feed.
Alternately,
keepers are held together in a group 600' which is formed as a stick.
According to some
assembly methods, keepers 220 are fed into a hitch feed where they are
separated from
one another via shearing, or cutting, of base 26 at severing points 62. Once
one of
keepers 220 is separated from group 600, the keeper may be picked and placed,
for
example, on surface 104 of spacer 30 (Figures 2A, C), for welding. Group 600
may
greatly facilitate automation of the assembly process. According to alternate
embodiments, individual keepers 220, not joined along a common base, are
joined
together by adhesive attachment to a release liner from which the keepers may
be pulled
either one-by-one or in groups.
[34] Figure 7A is a perspective view of an alternate embodiment of a muntin
bar keeper, and
Figures 7B-C are a perspective view and an end view, respectively, of another
alternate
8
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
embodiment of a muntin bar keeper. Figure 7A illustrates a muntin bar keeper
720
including a base 76, a first engagement element 701 and second engagement
element
702; each engaging element 701, 702 extends out from base 76, and first
engaging
element 701 is spaced apart from second engaging element 702 so that base 76
extends
therebetween to provide an area, which is shown including an optional weld
projection
724, for welding keeper 720 to a spacer, for example spacer 30. Figure 7A
fiuther
illustrates each engagement element 701, 702 including a pair of opposing legs
776 in an
A-frame structure, to provide for a press fit, a friction fit, or an
interference fit within an
interior portion of a muntin bar, wherein each leg 776 includes an extension
706, folding
outward and over toward base 76. Figures 7B-C illustrate a muntin bar keeper
720'
including a base 76' and first and second engaging elements 701', 702', which
extend out
from base 76' and are spaced apart from one another so that base 76' provides
an area
therebetween for welding, for example, to form weld joint 25 between keeper
702' and
surface 104 of spacer 30 (Figure 7D). Figures 7B-C further illustrate each
engaging
member 701', 702', like members 701, 702 of Figure 7A, including opposing legs
776,
which each include extension 706 folding outward and over toward base 76'.
According
to the illustrated embodiments, each pair of legs 776 acts like a spring,
wherein the
opposing legs bend toward one another, to allow for insertion into a muntin
bar, and press
outward against an inner surface of a wall of the muntin bar, once inserted.
Extensions
706 can facilitate insertion and provide a contact surface between engaging
elements 701,
702 and 701', 702'. With reference to Figures 7B-C, it should be noted that
engaging
members 701 ', 702' each further include tabs 726 extending inward from
corresponding
legs 776; tabs 726 provide a force opposing an inward bending of opposing legs
776
toward one another, thereby increasing an outward pressing force of legs 776
against an
inside surface of the muntin bar wall.
[35J Keepers 720, 720' may be more appropriate to support muntin bars having
rectangular
profiles, for example as illustrated in Figure 7D. Figure 7D is a cross-
section view, for
example, through section line A-A of Figure 1, according to an embodiment that
includes
a muntin bar 81 having a rectangular profile. Figure 7D illustrates the fit of
engaging
members 701', 702'of keeper 720' within a wall 801 of muntin bar 81. It may be
appreciated, with reference to Figure 7D, that the fit of engaging members
701', 702'
9
n 1
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
within bar 81 provides a stable attachment to hold bar 81 in a fixed relation
with
spacer 30. With further reference to Figure 7D, it may also be appreciated
that the
rectangular profile of bar 81 effectively hides keeper 720' from view when bar
81 is
attached to spacer 30.
[36] Figure 8A is a perspective view of yet another alternate embodiment of a
muntin bar
keeper. Figure 8A illustrates a muntin bar keeper 820 including a base 86 and
an
engaging element 800 extending out from base 86, such that base 86 includes
areas,
disposed on either side of element 800, for welding, for example, to form weld
joints 25
between keeper 820 and surface 104 of spacer 30, for example as illustrated in
Figure 8B.
Figure 8B is a cross-section view, for example, through section line A-A of
Figure 1,
according to an embodiment wherein engagement element 800 of keeper 820 holds
a
muntin bar 91, which has a substantially round profile, in a fixed relation
with spacer 30.
Figure 8A further illustrates engaging element 800 including opposing legs 886
extending toward one another in an A-frame structure to provide for a press
fit, or an
interference fit, within an interior portion of a muntin bar, for example,
muntin bar 91, as
shown in Figure 8B. According to the illustrated embodiment, legs 886 act like
a spring,
bending toward one another, to allow for insertion into muntin bar 91, and
pressing
outward against a wal1901 of muntin bar 91, once inserted. Each leg 886 is
shown to
include an extension 806, folding outward and over toward base 86, in order to
facilitate
the insertion into muntin bar 91 and to provide points of contact between
engaging
element 800 and an inner surface of muntin bar wal1901. Figure 9 is a cross-
section
view illustrating yet another alternate embodiment of a keeper, which may be
particularly
suited for the round profile of muntin bar 91. The keeper shown in Figure 9
includes
three engaging elements 301, 302, 303, each formed by a single leg, for
example, similar
to one of legs 886, which are disposed about a perimeter of a base 96 and
extend outward
therefrom; weld joint 25 is shown being formed in a central portion of the
base.
[37] With reference back to Figure 2A it may be appreciated that spacer 30,
having a width
FW of surface 104, may accommodate attachment of muntin bars of various cross-
sections, as long as corresponding keepers have widths MW less than width FW,
since no
special interlocking or mating features between the keeper and the spacer are
employed
by embodiments of the present invention. Furthermore, keepers of the present
invention
.
CA 02571165 2006-12-14
Practitioner Docket # 44046.103.272.2
Utility Patent Application
may be positioned anywhere along a surface of a spacer, for example surface
104 of
spacer 30, thereby providing flexibility for the manufacturing line to produce
a variety of
arrangements of muntin bars with a single type of spacer.
[38] In the foregoing detailed description, the invention has been described
with reference to
specific embodiments. However, it may be appreciated that various
modifications and
changes can be made without departing from the scope of the invention as set
forth in the
appended claims. For example, although various muntin bars are shown herein to
extend
orthogonally along two orthogonal planes which are approximately orthogonal to
a
surface of a spacer, to which a muntin bar keeper is attached, it is
contemplated that
engagement features of muntin bar keepers may be structured to allow muntin
bars to
extend in a plane skewed from one or both of the orthogonal planes.
11
