Note: Descriptions are shown in the official language in which they were submitted.
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REINFORCED CEILING RUNNER AND METHOD OF
REINFOF~CINt~ A CEILING RUNNER
Background of the Invention
Field of the Invention
5The invention is directed to a method of
fabricating a specific runner and, more particularly, to
a method of reinforcing the ceiling runner by using an
adhesive in conjunction with a mechanical bonding.
Description of the Prior Art
10U~S. Patent No. 4,206,578 is directed to a
typical double web capped T bar grid.
ll.S. Patent No. 3,845,544 is dir~ected to a
method of forming sheet metal structures wherein the
sheet metal components are glued together.
U.S. Patent No. 3,725,169 is directed to a
sheet metal structure where two metallic sheets are
bonded together.
U.S. Patent 3,029,914 is directed to a sheet
metal structure where two sheet metal structùres have
20 been adhesively joined together and the sheet metal
structures have also been fabricated to a specific
shape.
Summary of the Invention
The invention is directed to the method of
25 making a ceiling runner. The first step involves the
orming of an inverted T-shaped runner with a vertical
web and two horizontal flanges at the base of the web
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C3P-7136
with one horizontal flange being disposed p~rpen-
dicularly vn each side of th~ vertica~ we~.
A strip of material is applied to the under-
- side of both horizontal flanges wi~h the sides of the
strip of materidl extending beyond the edges of the
horizontal flanges. Each side of the strip of material
is wrapped around and slightly over each edge of the
horizontal flange whereby the bottom and edges of the
horizontal flanges are encased in the strip of material.
The improvement herein is in the application of an adhe-
sive material to the interface of the horizontal flanges
and the strip of material prior to their assembly. This
adhesive is heat activated after the product is mechani-
cally assembled to bond the strip of material and the
inverted T-shaped runner together.
The structure claimed herein is a structure
which results from the application of the above method
to form a product.
Brief Description of the Drawings
Fig. 1 is an end view of an inverted T-shaped
runner with a capped horizontal flange, and
~ Fig. 2 is a perspective view~of the inverted T
runner.
Description of the Preferred Embodiment
The purpose of the invention herein is to pro-
vide a method of adding strength to a T bar grid fabri-
cated with a double web and cap system. More
particularly, one desires to add strength in pounds per
foot deflection and in torque strength by twisting. The
addition of strength is achieved by coating the inside
portion of the cap strip or the bottom sides of the
flanged areas which attach to the cap strip with a "hot
melt" adhesive. The precoated metal is assembled in the
rolling mill by existing techniques. ~fter assembly,
3~ the fabricator applies heat to the yrid which activates
the adhesive and permits the adhesive to 10w or wet the
surfaces which contact one another. Cooling sets the
adhes~ive and results in the grid gaining a "unitized"
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str~cture. Heat may be applied by cont~ting the grid
with a hot surface, i.e., hot rolls or by passing the
grid through a heat tunnel, i.e., infrared lights.
Either heating system has proved capable of use with
S conventional hot melt adhesives. Testing has also shown
that reheating the grid to approximately 140 F will
soften the adhesive, however, the original strength is
returned by cooling. A number of advantages result from
the utilization of the process herein. It is possible
now to reduce the number of bends incorporated in the
cross-sectional configuration. Perhaps lighter gauge
metals may now be utilized to give the same properties
as current grid structures not containing the hot melt
adhesive. There is added value to the grid in that the
customer can feel by a comparison the improved strength
of the grid herein as compared to other grid structures
not containing the hot melt adhesive.
A grid member is conventionally formèd by
taking a piece of sheet metal of .010" to .013"
thickness steel and through the use of a conventional
metal formin~ technique convert it into an inverted
T-shaped runner, such as runner 2 of Figure 1. The
single piece of metal is basically bent in its center to
form the vertical rib form. The runner may be provided
with an enlarged top 6 or it could be simply formed by
bending the piece of sheet metal at its midpoint with a
180 fold. The ends of the piece of sheet metal are
bent out at a 90 angle from each side of the vertical
web ~ to form the two horizontal flanges 8 and 10.
These flanges are disposed perpendicularly to the
vertical web at the base of the vertical web as shown in
Figure 1.
Conventionally, a cap strip of material 12 is
applied to the horizontal flanges of the grid for both a
decorative effect and also to cover up the gap that
exists between the two webs of material forming the ver-
tical web 4 of the runner. The cap strip 12 would be of
.010" thickness steel and would be slightly wider than
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the width of the hori~ontal ~lang~ ~ ~nd 10 as measured
from the edge of one horizontal flang~ to the edge of
the opposite horizontal ~lange. Through a conventional
metal fonning technique the sides 14 of the strip of
S material 1~ are folded around the edg~ of the horizontal
flange and are placed slightly above the top edge of the
horizontal flange to form the structure shown in Figure
1. Consequently the bottom and edges of the horizontal
flange are encased in a strip of material.
The above structure is conventional in the art
as shown in U.S. Patent No. 4,206,578. The inven~ion
herein lies in the application of a hot melt adhesive to
either the underside of flanges 8 and 10 or the upper
surface of the strip of material 12 prior to the time
that these two elements are assembled. A particularly
good hot melt adhesive that could be utilized is the
adhesive of Roberts Consolidated Industries sold under
the trade name Superstick. After the a~hesive coating
is applied, the flanges 8 and 10 and the piece of
material 12 are assembled in a conventional manner as
above described. It is believed that the invention
herein is not restricted to jus~t the ~use of a hot melt
adhesive, but any adhesive or even solder could be
utilized which would tend to bond together the two
elements forming the horizontal flange of inver~ed T
runner. If a hot melt adhesive is used, the adhesive
would be heated to approximately 220 F which will
soften the adhesive and upon its cooling the adhesive
will be bonded to the metal surfaces and consequently
bond together the metal surfaces.
As a result of the use of the adhesive, the
torque strength of a conventional runner is noticeably
improved. If one would take the runner structure of
Figure 2, which is a conventional capped runner
structure, and grasp it at both ends and twist it in the
direction shown by the arrows there would be an
application of torque to the runner and this would
provide an indication of the torque strength of the
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runner. The presence or absence of the hot melt
adhesive makes a very noticable change in the torque
, ~ strength and there is a substantial increase in the
torque strength of the inverted T-shaped runner using an
adhesive at the interface between the bottom of
horizontal flanges 8 and 10 and the top of the piece of
material 12. The placement of the adhesive can also
affect the load strength which is the load the runner
will support on its horizontal flanges.
As originally applied, the adhesive was placed
as shown in Figure 1. Here the adhesive 16 was along
the whole surface of the bottom of the horizontal flange
and even e~tended partly between the vertical web
members. Subsequent application placed the adhesive
lS just between the vertical web members and not on the
horizontal flanges, or just on the ends of the
horizontal flanges and not on the rest of the horizontal
flanges (the center region of the flanges) or between
the vertical web members. Placing the adhesive only
between the vertical web members gave improved torque
strength, but no improved vertical load strength while
placing the adhesive only at the ends of the horizontal
flanges increased both torque and vertical load
strengths.
