Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED STONE SLAB MOUNTIN~
SCOPE OF THE INVENTION
This invention relates to the mounting of stone
slabs to structures, and more particularly to the supportin~
of thin sheets of granite, marble or other masonry to form
an exterior facade.
BACKGROUND OF THE INVENTION
In the past stone slabs forming an exterior facade
of buildings have been secured to the building structure
utilizing adhesives. However, some building codas now
require stone slabs be mechanically coupled to structures.
Previously known mechanical systems to mount sto;ne slabs
have not been satisfactory.
For example, U.S. Patent 4,060,951 to ~ere teaches
a mechanical mounting system in which a plug hole is drilled
into the edge of a slab to intersect at right an~les with a
bolt hole drilled into the rear of the slab. A bolt in-the
bolt hole is threaded into a plug in the plug hole.- Wi~h
the bolt secured to the structure, the bolt and plug co-
operate to mechanically mount the slab to the structure. In
Gere location of the plug hole on the edge of the slab is
: disadvantageous as difficult to access to drill the hole
and, particularly in an assembled facade, to access the hole
as may be necessary to change a slab. Moreover, the
location of the plug hole and bolt hole near an edge is
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1 ~isadvantageous as being a location where the slab may most
readily fracture thus substantially reducing the forces
which the mechanical mounting may withstand, as determined
by t~e nature of the stone slab being used and particularly
its thickness.
U.S. Patent 3,786,605 to Winfrey teaches a
mechanical system for mounting slabs by slots cut into the
top and bottom ends of the slabs into which pins may
vertically extend supported on metal supports extending
horizontally from the structure. In Winfrey location of the
slots along the edges of the block reduces the ultimate
strength of the system.
UOS. Patent 4,531,338 to Donalt provides two studs
which extend at an angle with respect to each other,
diverging away from each other, into a slab with the rear
ends of the studs crossing rearward of the slab. By
encasing the crossing rear ends in enclosed pockets filled
with epoxy, ths rear ends of the studs effectively form a
closed loop secured to the structure. Donalt has the
disadvantage of being complex to assemble and relying on the
epoxy bonding to maintain the joint. Further Donalt limits
its structure to being a poured concrete slab. Donalt is
not practical on steel structures.
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l SUMMARY OF THE INVENTION
~ccordingly, i-t is an object of the present
invention to at least partially overcome the disadvantages
of the prior art by providing a slab mounting with a bolt
hole and a pin hole both extending from the rear surace
into the slab to intersect with the pin hole to pass through
the~ bolt hole and end in the-slab therepast, wherein a pin
in the p.in hole extends through a bolt in the bolt hole with
the pin coupled to the bolt and extend:Lng in the pin hole
into the slab on either side of the bo:t hole~
Another object is to provide a mechanical mounting
which increases the maximum forces which may be withstood
thereby and which permits safe use of 1:hinner slabs of
stone, concrete and similar materials.
Another object is to provide a mechanical moun~ing
for a facing slab which forms an integral truss and can
readily be coupled to and adjusted relative to the support
structure. ~ :
Another object is to provide a method of assembly
of a pre-fabricated wall panel.
In one of its aspects the present invention
provides a wall assembly wherein a facing slab is mounted to
a support structure, the slab having a rear surface, the
improvement comprising:
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1 a first bore extending into the slab from the rear
surface and ending at a first blind end,
a second bore extending into the slab from the
rear surface to intersect the first bore, through the first
bore, and into the slab beyond the first bore where the
second bore ends at a second blind end,
~ first elongate bolt means having a front portion
in the first bore and a rear portion which extends
rearwardly from the rear surface of the slab,
a threaded first aperture through the first bo-lt
means coaxially aligned with the second bore,
threaded elongate pin means having a front portion
in the second bore and a rear portion which extends
rearwardly from the rear surface of the slab,
the front portion of the pin means disposed in the
second bore in threaded engagement within the first aperture
of the first bolt means and passing through the first bore
at least partially into that segment of the second bore in
the slab beyond the first bore,
second elongate bolt means having a front po~tion
and a rear portion with the rear portion carrying first
means for coupling to the support structure,
the rear portion of one of the pin means and the
. first bolt means coupled to the front portion of the second
bolt m~ans,
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1 the rear portion of the other of the pin means and
the first holt means carrying secon~ means for coupling to
the support structure,
the rear portion of the second bolt means being
disposed parallel to the rear portion of the other of the
pin means and the first bolt means,
~ the first and second means or coupling to the
support structure providing for movement of the second bolt
means and the one of the pin means and first bolt means in a
direction parallel to that in which the rear portion of the
second bolt means is disposed and providing for ad ustable
locking at different positions, and
wherein upon locking the first and seconcl coupling
means the first and second bolt means and the pin means form
with the support structure a rigid truss to support: and
anchor the slab.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects and advantages will appear from
the followlng description taken together with the
aFcompanying drawings in which:
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1 Figure 1 is a pictorial view of a stone slab
mounted to a metal frame of a modular wall pane] in
accordance with the present invention;
Figure 2 is an exploded view of a first embodiment
S f a bolt ~ember and a complementary pin member shown over a
cross-sectional top view.of a segment of the slab of
Figure 1 showing a bolt hole and pin hole therein;
Figures 3 and 4 are cross-sectional side and top
views, respectively, of a first embodiment of a mounting of
this invention utilizing the bolt member and pin member
shown in Figure 2;
Figures S and 6 are cross-sectional side and top
views, respectively, of a mounting similar to that in
Figures 3 and 4 but with a bracket to assist in carrying
vertical loading;
Figure 7 shows a schematic cross-sectional side
view through a slab drilled to accept the mounting of the
present invention;
Figure 8 shows a schematic cross-sectional side
view through a prior art slab drilled to accept a mounting
of U.S. Patent to Gere,
Figure 9 shows a cross-sectional side view of
another embodiment of a mounting in accordance with the
present invention,
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l Figure 10 shows a cross-sectional side view of y~t
another embodiment of a mounting in accordance with the
present invention, and
Figure 11 shows an exploded pictorial view of a
number of the components of the embodiment of Figure 10.
DESCRIPTION OF PREFERRED E~BODIMENTS
Reference is made first to Figure 1 which s'nOws a
slab 10 of stone securely coupled to a metal framework 12 at
f~ur locations by mountings of the present invention
generally indicated as 14. Frame 12 comprises horizontal
angle beams 16 and vertical angle beams 18. These beams are
illustrative only and may comprise portions of a metal frame
f~r a modular wall panel to be pre-fabricated to include a
plurality of stone slabs. A complete wall panel may be
transported to a building site and coupled to a building as
a unit.
Frequently used stone slabs have a thickness of
about 1 to 2 inches and varying width and length, requently
about 5 to 6 feet in width and 5 to 6 feet in length.
Figure 2 best shows the two holes drilled into the
rear of slab 10. Slab 10 has a bolt hole 20 drilled to
extend into the slab from rear surface 22 approximately
perpendicular to re-r surface 22. ~olt holc 20 extends from
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1 a rear entrance 21 on rear surface 22 forward to a first
blind end 24.
Slab 10 also has a pin hole 26 drilled to extend
into slab 10 from rear surface 22 and angled to intersect
boIt hole 20. Pin hole 26 commences at a rear entrance 27
on rear surface 22 which i5 spaced to one, first side from
the~ rear entrance 21 of.bolt hole 20. The pin hole 26
extends forwardly from its rear entrance 27 at an acute
angle to the bolt hole so as to pass, as a first segment 28,
through the slab to the bolt hole, through the bolt hole and
then to extend, as a second segment 30, into the slab on the
other, second side of the bolt hole ending at second blind
s end 32-
A first embodiment of a bolt member 34 and
complementary pin member 40 is shown in Figure 2, in an
orientation generally as adapted to be received in the holes
20 and 26 in slab 10 therebelowO
Bolt member 34 has a front end 35, a rear end 36
and a generally cylindrical side surface 37 which is
threaded near its rear end for coupling to angl~ beam 16.
An aperture 38 extends through bolt member 34 from aperture
entrance opening 38a to aperature exit opening 38b.
Pin member 40 is also generally cylindrical and
has a forward end 42 and a rear end 44.
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1 As seen in Figures 4 or 6 bolt member 34 i5 to be
located in bol-t hole 20 with it.s front end 35 near first
blind end 24 and the bolt to extend rearwardly out the bolt
hole to its rear end 36. Bolt member 34 can be coupled near
its rear end to angle beam 16.
Aperture 38 is located in bolt member 34 so that
with bolt member 34 located within bolt hole 20, aperture 38
can be coaxially aligned with segments 28 and 30 of pin hole
26.
Pin member 40 is to be located in pin hole 26
extending via aperture 38 through bolt member 34 so that pin
member 40 lies in both the segments 28 and 30 of pin hole 26
with the forward end 42 of pin member 40 near second blind
end.32 of pin hole 26 and the rear end 44 of pin member 40
lS near rear entrance 27 of pin hole 26.
Pin member 40 frictionally engages bolt member 34
inside of aperture 38. As best seen in Figure 2, pin member
40 preferably carries raised lon~itudinally extending
serrations 46 sized to be received in force fit relation in
aperture 38 to resist removal of pin member 40 therefrom.
With pin member 40 inserted into aperture 38, bolt member 34
can not be removed from bolt hole 20 and bolt member 34 is
thus mechanically coupled to slab 10.
Figure 2 shows a first embodiment of a bolt member
34 and a complementary serrated pin member 40 which are also
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1 illustrated in Figures 3 to 6. Fiyure 9 shows a second,
preferred embodiment of bolt member 34 and a complementary
threaded pin member 40 carrying external threads 41 adapted
to engage internal threads provided inside aperture 38. In
Figure 9, identical reference number are used to show
elements similar to those in the embodiment of Figure 2. In
thè embodiment of Figure 9, with pin member 40 threaded into
aperture 38, bolt member 34 can be secured against removal
from a slab 10.
Bolt hole 20, pin hole 26 and aperture 38 are
cylindrical bores with bolt member 34 and pin member 40
being cylindrical rods of complementary size. Bolt hole 20
preferably is sized to relatively closely, slidably receive
bolt member 34 coaxially therein with the bolt hole 20
marginally greater than the bolt member. Similarly, pin
hole 26 is complementarily sized to closely, slidably
receive pin member 40 coaxlally therein. Preferab:ly, with
pin member 40 received in aperture 38 of bolt member 34,
axis 53 of pin member 40 intersects with axis 60 of bolt
member 34. Preferably in the first embodiment of Figures 1
to 6 where the bolt member 34 extends rearward from slab 10
approximately normal to rear surface 22, axis 58 of the pin
member 40 and axis 60 of the bolt member 34 intersect to
form an acute angle A therebetween (as seen in Figure 2)
rearward of the intersection of the axes. Preferably this
l angle may be in the range of 30' to 60', more preferably 35'
to 50'. Figure 2 shows an angle of about 45'.
While not clearly shown in the drawings when bolt
member 34 and pin member 40 are received in slab 10, voids
in bolt hole 20 and pin hole 26 not occupied by the bolt
member or pin member are preferably filled with an adhesive
water impermeable filler such as known epoxy compounds.
Preferably, the rear entrances 21 and 27, respectively, to
bolt hole 20 and pin hole 26 will be sealed against moisture
penetration to keep water from entering the bolt hole or pin
hole.
~olt member 34 preferably has a squared-of,
forward end 35 so that its cylindrical side wall 37
terminates abruptly at forward end 35 as a radially disposed
end surface. Aperture exit opening 38b preferably is
located on the bolt member 34 close to forward end 35 but
entirely within the cylindrical side surface 37 of bolt
member 34. This is advantageous in that rearward forces
attempting to draw the bol.t rearwardly from the slab will
substantially be resisted by a forwardmost section 64 of pin
member 40 best shown in Figure 6 which extends through bolt
member 34 and is received in the second segment 30 of pin
hole 26. The rearward forces will attempt to bend this
forwardmost section 64 towards the front to withdraw bolt
member 34. With at least a small segment 66 of the
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l cylindrical side wall 37 of bolt member 3~ being provided
forward of aperture exit opening 38c bolt member 3~ assists
in supporting pin member 40 to resist bending. Lesser
support would be provided to pin member 40 if, for example,
aperture exit opening 38c were in the end surface of bolt
member 34. It is advantageous that aperture exit opening
3~c be close to the forward end 35 so that for~7ardmost
section 64 of pin member 40 may not have an excessive
length, having regard to the distance which the second blind
end 32 may be desired to be located perpendicularly from
rear surface 22.
Mountings oE the present invention advantageously
resist failure of the slab arising as a result of either
rearward directed forces acting on the bolt member and
a1:tempting to pull the bolt member rearward out of the slab
in a direction indicated by arrow R in Figure 7 or forward
directed forces acting on the bolt member and attempting to
push the bolt member forward through the slab as indicated
by arrow F. When stone slabs such as marble fail as a
result of such forces, failure typically occurs along a
conical line of fracture, with the angle of the cone being a
characteristic of the stone. The surface area of the
fracture typically represents the failure strength of the
mounting and such surface area increases with increases in
the depth of the apex of the cone from a surface towards
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1 which the forces are ac-tiny. The surface area o~ the
fracture will be decreased where the axis of the cone is
located near edge surfaces of a slab.
Figure 7 illustrates the bolt hole and pin hole in
a mounting in accordance with the present invention. Broken
lines 68 represents a typical fracture line in -the event the
slab carrying a mounting of this invention may fail under a
rearwardly directed force R acting on a bolt member.
Rearward fracture line 68 generally extends from an apex 101
near second blind end 32 rearwardly to rear surfaces 22 at
an angle typical of the angle of fracture for a stone s~ab.
Figure 2 also schematically shows the same
rearward fracture line 68 as shown in Figure 7. It is to be
appreciated that a cone of material will become disengaged
from the slab on rearward withdrawl of bolt member 34. ~his
cone is roughly defined by rotating rearward fracture line
68 about rearward cone axis, CR, shown in Figures 2 and 7.
In Figure 2, the intersection of the rearward fracture line
68 with rear surface 22 is shown as dotted line 69.
Figure 2 shows the rearward cone axis, CR, as passing
through apex 101 and perpendicular to rear surface 22.
Dotted lines 70 in Figure 7 represent a typical
fracture line for failure under a forwardly directed
force F. Forward fracture line 70 extends forwardly from an
apex 100 forward of the intersection of the pin hole and
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1 bolt hole. A cone of material to be detached in such
forward failure is roughly defined by rotating forward
failure line 70 about forward cone axis, CF,. Forward coné
axis CF, is shown passing thrGugh apex 100 normal to rear
surface 22.
If a substantial diameter pin member is used, a
sector of the fracture surface may originate as a partial
cone from a second apex at rear entrance 27 as shown by
dotted and broken line 71. With fracture line 71 extending
substantially -the entire width of the slab, it may to some
extent increase the resistance to forward fracture.
Pin hole 26 may extend a substantial distance
through the slab toward the front surface 72 of slab 10
shown in Figure 7, to increase the resistance to rearward
forces, R. Pin hole 26 could extend entirely through the
slab although this is not preferred due to moisture sealing
problems and consideration regarding visual appearance of
front surface 72.
Figu~es 3 to 6 illustrate slab 10 as a 1 1/4 inch
thick granite slab in which first blind end 24 is located
about 7/8 inch from rear surface 22, that is , with bolt
hole 20 extending about 70% of the thickness of the slab.
The second blind end 32 of pin hole 26 preferably is located
at least as far from rear surface 22, measured perpendicular
thereto, as the first blind end 24, more preferably ~arther
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1 from rear surface 22. Second bllnd end 32 can readily be
located at least 50% of the thickness of the slab from rear
surface 22 and more preferably at least 2/3 of the
thickness.
Figure 8 shows the prior art mounting of U.S.
Patent 4,060,951 to Gere showing a plug hole 74 drilled into
a slab 10 from a rear surface 22 and a bolt hole 76 drilled
into the slab from an edge surface 78. A rearw~rd fracture
line 80 and a forward fracture line 82 are shown. The cone
axis for both forward and rearward fracture is expected to
be the same and is .shown as axis C on Figure 8, normal to
rear surface 22. The apex of rearward fracture 103 and the
apex of forward fracture 104 are each located less than one
half the thickness of the slab from the surface to whiçh the
respective fracture extends. Locating the plug hole 74
closer to the front or rear surface of the slab will
decrease one of fracture lines 80 and 82. With the apex of
both fracture lines close to the edge surface 78 of the
slab, the surface area of the cone of fracture is
substantially reducted.
Figure 1 shows slab 10 coupled to framework lZ by
four mountings 14. The lower most mountings are shown in
Figures 3 and 4 while a preferred configuration ~or the
uppermost mountings lS shown in Figures 5 and 6.
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1 Referring to Fiyures 3 and 4, bolt member 34 is
threaded near its rear end 36. Bolt member 3~ passes
through enlarged bore 87 in angle beam 16 and is securely
locked thereon by threaded nuts 84 and 88 and washers 85 and
5` 86. The particular prefabricated panel illustrated has a
water impermeable inner layer of sheet metal 90, an
insulation layer 91, an air space 92 and an outer layer of
slabs 10. With slabs 10 thus hung spaced horizontally ~rom
angle member 16, it is preferred to provide mechar~ical
reinforcement to assist bolts 34 in carrying the vertical
loading.
Such reinforcement is shown in Figures 5 and 6
wherein metal bracket 93 ,losely engages bolt member 34 at
the front end of the brac,cet. The rear end of the bracket
is secured to angle beam 16 by bracket channel 95 and
flanged sleeve 94 therein sandwiching the rear of bracket 93
between the angle beam 16 via a washer 96, jam nut 97
threaded on sleeve 94, tandum nut 98 threaded to both sleeve
94 and bolt member 34 and lock nut 99 threaded on bolt
member 34.
The pre-fabricated panel may conveniently be
formed by laying the slahs with their front surfaces 72
down, drilling the bolt holes and pin holes with assistance
of a jig, inserting the bolt members and pins members and
then lowering frame 12 down over the bolts member.
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1 As seen in Figures 2 to 6, pin member 40
preferably extends horizontally into slab 10.
In accordance with the present invention in a
1 1/4 inch granite slab bolt holes and pin holes were
drilled as shown in Figures 2 to 4 to be located 7/~ inch
from the rear surface with the pin hole at a 45 angle to
thè bolt hole. The pin hole was 1/8 inch diameter and the
pin a 1/8 inch diameter stainless steel pin 1 1/4 inches
long. The bolt hole was 5/16 inch diameter and the bolt
member a 5/16 inch stainless steel bolt. Under stress tests
~ithout any epoxy, the slab withstood rearward forces R
acting of the bolt member of up to 2Z00 pounds.
Reference is now made to Figure 9 showing a
horizontal cross-sectional top view through another
embodiment of a mounting in accordance with the present
invention. Whereas in Figures 3 to 6, bolt hole 20 is
perpendicular to rear surface 22, in Figure 9, the axis 60
of the bolt hole forms an acute angle with the rear surface
22. The axis 58 of the pin hole in Figure 9 also is shown
forming an acute angle with rear surface 22. Preferably
each of the bolt hole and pin hole form angles of not less
than about 30 and, more preferably, not less than about
45, with the rear surface. Preferably, the axis of the
bolt hole and pin hole form, rearward of their intersection
an angle R therebetween not less than about 30, and not
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1 greater than about 120. Preferably angle B may be in the
ramge o~ between about 45 amd 90 .
Figure 9 shows pin member 40 having external
threads 41 complementary to internal threads in
aperture 38. Figure 9 also shows both pin member 40 and
bolt member 38 optionally extending rearwardly from the slab
to angle beam 16 where both the pin member and bolt member
are shown coupled to beam 16 by welds 84. With this
configuration the pin member, bolt member and support frame
form a truss which will preferably support a slab with out
the need for mechanical reinforcing of the bolt against
deflection as with the metal bracket shown in Figures 5 and
6. In providing a preferred truss the axis 58 and 60 of pin
member and bolt member may be lie in the same vertical
plane.
In assembly of the configuration of Figure 9,
after screwing the pin member into the bolt member, the pin
member may then be secured as by welding to beam 16.
While Figure 9 shows a truss being formed with
bolt member 34 and pin member 40 coupled to beam 16 by
welding, either could be secured by other methods such as
threadi~g or bolting.
In the illustrated preferred embodiment of
Figur 1, a frame 12 is composed of metal beams.
Alternately the frame may comprise a pre-cast concrete panel
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1 to which the slabs 10 are coupled via the bolt members and
pin members, for example with threaded coupling or with the
bolt member and pin member impregnated in or otherwise
attached to the pre-cast concrete panel.
The slab of material to be supported to provide
the decorative facing may comprise many fragible materials
including natural stone, pre-cast concrete, artificial
stone, plastic, fiberglass, glass and bonded composites
thereof. Prei-erred natural stones are marble and granite.
Reference now made to Figures 10 and 11 which show
a further embodiment of a mounting in accordance with the
present invenl:ion. As with the other figures showing
different embodiments of the invention, similar reference
numerals are used to show equivalent elements.
The embodiment of Figures 10 and 11 is a
modification of the embodiment shown in Figure 2. In
respec-t o~ Ficlure 10, bolt member 34, bolt hole 20, pin hole
26 and pin member 40 are substantially the same as that
shown in Figure 2 with a notable exception that pin
member 40 is threaded and extends rea~wardly beyond slab
10. In Figures 10 and 11, rea~ end 44 of pin member 40
extends rearwardly to a second bolt member 110. Second bolt
member 110 has a threaded aperture 122. A front portion of
pin member 40 is threadably received in aperture 38 in the
front portlon of first bolt member 34 while a rear portion
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1 of the pin member 40 is threadably received within aperture
122 in the front portion of second bolt member 110. Pin
member 40 is thus in threaded engagement with both the kolt
members.
In Figures 10 and 11, both primary bolt member 34
and secondary bolt member 110 are securely coupled to angle
beam 16 of frame 12. Beam 16 may be seen to comprise a thin
plate-like beam having surfaces normal to the axis of both
bolt members. With pin member 40 threaded into each of the
two bolt members 34 and 110, a truss is formed which
increases the strength of the coupling and assists in
carrying the weight of slab 10.
Figures 10 and 11 show both primary bolt member 34
and secondary bolt member 110 as having threaded rear
portions coupled to angle beam 16 by compression of
washers 85, 86 and 86a between threaded nuts 84 and 88 onto
beam 16. Lock nut 88a may also be provided.
Angle beam 16 has apertures 87 through which bolt
members 34 and 110 pass. Apertures 87 are sufficiently
greater in diameter than the bolt members to permit precise
location of the bolt members at desired locations by
accomodating movement of the frame, during assembly radially
of the bolt members. Washer 85 is also provided with a
central aperture 112 substantially greater than the diameter
of the bolt members. With the diameters of both aperture 87
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1 and aperture 112 greater -than that of the bolt members,
torroidal (doughnut shaped) annular spaces 114 and 116 are
defined radially between the bolt member and each of beam 16
and washer 85, respectively, as seen in Figure 10. Nut 84
carries a recessed slot 118 in its axial end surface facing
towards angle beam 16. The angular spaces permit access,
from the upper rear side of beam 16 as seen in Figure 11 to
slot 118 in nut 84. ~ screwdriver or other tool may be
passed through the annular spaces to engage slot 118 and
turn nut 84 to locate nut 84 at a desired location, for
example, snug against the iorward surface of sheet 90.
,~ In fabrication oi a wall panel, slabs 10 may be
laid on a flat surface with their front surfaces 72 down.
The bolt holes and pin holes may be drilled into the
upwardly facing rear surface 22 as with a jig. Bolt member
34 and pin member 40 are then inserted and screwed together
with second bolt member 110 either pre-threaded onto pin
member 40 or threaded onto pin member 40 after coupling of
pin member 40 with bolt member 34. With both bolt member 34
and second bolt member 110 extending rearwardly from the
slab and preferably with their threaded rear portions
parallel and perpendicular to the rear surface of the slab
then nuts 84 and washers 85 are placed on both bolt
members. Subsequently a prefabricated frame 12 carrying
angle beam 16 with suitably spaced apertures 87 is lowered
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1 down over the bolt members with the bolt members to protrude
upwardly through the apertures. Frame 12 may be held at a
desired height above the slabs and preferably to some extent
spaced above nuts 84 and washers 85. Slots 118 of nuts 84
can then be engaged with a suitable tool through apertures
87 and 112 from above frame 12 so as to turn nut 84 to draw
~ut 84 and washers 85 upwardly into snug engagement against
angle beam 16. Thereafter washers 86 and 86a and nuts 88
and 88a may be applied to lock the bolt members to frame
12. This method of assembly will result in each of slabs 10
heing held parallel to frame 12 at desired equal distances
in front of the fram~. Nuts 84 are not accessible from
below frame 12 due to continuous sheet 90. Nuts 84 can
after assembly be accessed from the rear of frame 12 by
removal of bolts 88, 88a and washers 8~ and 86a if
adjustment of location of a slab may be desired.
While a simple slotted screwdriver may be used to
access slot 118, a specially adapted tool with a fork-shaped
end to engage slot 118 on both sides of the bolt can be
easily fashioned.
The embodiment of Figures 10 and 11 is preferably
disposed with pin member 40 in a vertical plane so as to
form a rigid truss which will assist in bearing the weight
of slab 10 without bending of the bolt member 34~
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l Preferably bolt mernber 34 and bolt member 110 will
be parallel and with the axis of pin member 40 intersecting
the axis of the bolt members at identical angles. The holt
members are most conveniently perpendicular to angle beam 16
although this is not necessary and washers 85 and 86 could
be provided to be wedge shaped and accomodate the
intersection of the bolt members with t:he angle beam at an
angleO
Advantageous results have been obtained using a
3/16 inch diameter rod as pin member 4() and a 3/8 inch
diameter rod for the bolt members.
Figures lO and ll show pin member 40 preferably
having a smaller diameter than that of the bolt members.
Alternatively, pin member 40 could have a larger diameter
lS than both bolt members with the bolt members to be threaded
into apertures provided through pin meMber 40.
While the invention has been described with
reference to preferred embodiments it is not so limited.
Many modifactions and variations will now occur to those
skilled in the art. For a definition of the invention,
reference is made to the attached claims.
