U.S. patent application number 10/301262 was filed with the patent office on 2004-05-27 for method and apparatus for anchoring hardwood floor systems.
Invention is credited to Haytayan, Harry M..
Application Number | 20040098926 10/301262 |
Document ID | / |
Family ID | 32324510 |
Filed Date | 2004-05-27 |
United States Patent
Application |
20040098926 |
Kind Code |
A1 |
Haytayan, Harry M. |
May 27, 2004 |
Method and apparatus for anchoring hardwood floor systems
Abstract
A standoff sleeve/fastener assembly and a powered driver are
provided for anchoring a subfloor component of a hard wood floor
system to a concrete slab. The sleeve has a peripheral flange and a
countersink at a first end. The fastener is disposed in the sleeve
and has an enlarged head that is adjacent to but spaced from the
first end of the sleeve. The driver has a nozzle with a striker
bore sized to receive the head of the fastener and a recess sized
to accommodate the peripheral flange of the sleeve. The subfloor
component is anchored by (1) positioning the sleeve/fastener
assembly in a hole in that component with the bottom end of the
sleeve contacting the concrete slab, (2) positioning the driver
nozzle so that the fastener head and the flange of the sleeve
reside in its striker bore and recess respectively, and (3)
operating the driver whereby its striker impels the fastener to (a)
pierce and penetrate the concrete slab and (b) lock the sleeve
between the concrete slab and the head of the fastener.
Inventors: |
Haytayan, Harry M.; (Nashua,
NH) |
Correspondence
Address: |
Pandiscio & Pandiscio
470 Totten Pond Road
Waltham
MA
02451
US
|
Family ID: |
32324510 |
Appl. No.: |
10/301262 |
Filed: |
November 21, 2002 |
Current U.S.
Class: |
52/40 |
Current CPC
Class: |
F16B 15/00 20130101;
F16B 19/14 20130101; E04F 15/225 20130101; B25C 1/188 20130101 |
Class at
Publication: |
052/040 |
International
Class: |
E04H 012/00 |
Claims
What is claimed is:
1. Method for anchoring to a concrete base an attachment assembly
for a wood floor wherein said attachment assembly comprises an
attachment member that has top and bottom surfaces and having at
least two holes each with a counterbore extending down from said
top surface, and at least two compressible pads each having a top
side and a bottom side with said top side contacting said lower
surface of said attachment member, said method comprising the
following steps: (1) inserting (a) a sleeve having center bore, a
distal end, a proximal end and a peripheral flange at said proximal
end into each of said holes so that said peripheral flange resides
in said counterbore and (b) a fastener having a distal end and a
proximal end with an enlarged diameter head at said proximal end
into each of said sleeves, with said distal end of said sleeve
projecting below said attachment member by a predetermined amount
so that it is substantially flush with the bottom side of said each
compressible pad and with said head of said fastener extending
above said proximal end of said sleeve; (2) providing a manually
operable pneumatic driver having a nozzle with an end surface that
is sized to fit in said counterbore, a striker mounted for axial
movement in a striker bore in said nozzle with said striker bore
having a diameter at least equal to the diameter of said head of
said fastener, and means for reciprocally driving said striker
through (a) a rapid drive stroke whereby said striker is moved from
an at-rest position in which the striker is withdrawn into said
bore to an extended fastener-driving position in which said striker
projects beyond said end surface and (b) a rapid return stroke
whereby the striker is withdrawn from said fastener-driving
position back to said at-rest position; (3) positioning said driver
so that said end surface of said nozzle resides within said
counterbore and so that said fastener head resides in said bore;
and (4) operating said driver so as to cause said striker to impact
said fastener head with a force sufficient to drive said fastener
into said base far enough to cause the head of said fastener to (a)
drive said flange into tight engagement with said attachment member
and (b) force said sleeve into tight engagement with said base.
2. Method according to claim 1 wherein in step (1) the head of said
fastener extends above said attachment member.
3. Method according to claim 1 wherein in step (4) the depth of
penetration of said fastener into said base is limited by said
sleeve.
4. Method according to claim 1 wherein said distal end of said
fastener is substantially flush with said distal end of said sleeve
prior to step 3.
5. Method according to claim 1 wherein said sleeve has a tapered
countersink for said bore at said proximal end, and said fastener
head has a conical side surface.
6. Method according to claim 5 wherein the angle of taper of said
fastener is greater than the angle of taper of said
countersink.
7. Method according to claim 6 wherein said countersink has a taper
angle of about 60.degree. and said conical side surface has a taper
angle of about 82.degree..
8. A fastener/standoff sleeve assembly for use in anchoring an
attachment assembly for a wood floor to a concrete base, said
assembly comprising: a fastener having a shank with a distal end
and a proximal end, a pointed tip at said distal end, and an
enlarged diameter head at said proximal end, with said head having
a side surface that is tapered inwardly; and a sleeve for
positioning said fastener in a hole in said attachment assembly,
said sleeve having a distal end, a proximal end, a central bore
that extends between said distal and proximal ends for
accommodating the distal end of said shank, and a tapered
countersink for said bore at said distal end of said sleeve, said
countersink being shaped to accommodate said head of said fastener
when said fastener is driven into said sleeve by an impact on said
head while said sleeve is immobilized against axial movement.
9. A fastener/standoff sleeve assembly according to claim 8 wherein
said fastener head has a conical side surface that has a taper
angle greater than the angle of taper of said countersink.
10. A fastener/standoff sleeve assembly according to claim 8
wherein said fastener shank has a proximal relatively large
diameter portion and a distal relatively small diameter portion,
and said hole is sized to accommodate said distal relatively small
diameter portion but not said proximal relatively large diameter
portion.
11. Method for anchoring to a concrete base a floor attachment
assembly that comprises a floor attachment member having top and
bottom sides, at least two compressible pads attached to the bottom
side of said floor attachment member, and two holes extending
through said attachment member, said method comprising the
following steps: (1) providing a fastener and sleeve assembly that
includes a fastener having a shank with a leading end and a
trailing end and a radially-projecting head at said trailing end,
and a sleeve having an axial bore, a bottom end and a top end with
a radially projecting flange at said top end, said leading end of
said shank intruding into said axial bore; (2) inserting said
fastener and sleeve assembly into said one of said holes with said
bottom end of said sleeve projecting below the bottom side of said
attachment member and with the head of said fastener disposed above
and spaced from the top side of said attachment member; and (3)
impacting said fastener head with a pneumatically-powered hammer
with sufficient force to drive said fastener into said concrete
base far enough to cause the head of said fastener to (a) force
said flange into tight engagement with said attachment member and
(b) anchor said attachment member to said base without compressing
said pads.
12. Method according to claim 11 wherein in step (1) the head of
said fastener extends above said attachment member.
13. Method according to claim 11 wherein in step (3) the depth of
penetration of said fastener into said base is limited by said
sleeve.
14. Method according to claim 11 wherein said sleeve has a tapered
countersink for said axial bore at said proximal end, and said
fastener head has a conical side surface.
15. A fastener/standoff sleeve assembly according to claim 8
wherein said sleeve has a peripheral flange at its said proximal
end.
16. A fastener/standoff sleeve assembly according to claim 8
wherein said fastener has it shank inserted into said central bore
of said sleeve, with said enlarged diameter head and the portion of
said shank adjacent said head projecting from said proximal end of
said sleeve.
17. A fastener/standoff sleeve assembly according to claim 16
wherein said fastener shank is gripped by said sleeve.
18. A fastener/standoff sleeve assembly according to claim 16
wherein said tip is substantially flush with said distal end of
said sleeve.
19. A fastener/standoff sleeve assembly according to claim 18
wherein said sleeve has a peripheral flange at its said distal end
and said enlarged diameter head of said fastener is spaced from
said flange.
20. A fastener/standoff sleeve assembly according to claim 8
wherein said distal end of said sleeve has an end surface, said
shank is stepped with a relatively large diameter portion extending
distally from said head and a relatively small diameter portion
extending between said tip and said relatively large diameter
portion, and said relatively small diameter portion is disposed in
said bore with said tip being substantially even with said end
surface.
Description
FIELD OF THE INVENTION
[0001] This invention relates to hardwood floor systems and more
particularly to an improved method and apparatus for anchoring such
systems to a base made of concrete or like material.
BACKGROUND OF THE INVENTION
[0002] Hardwood floor systems used for sports, such as basketball,
require a significant degree of cushioning or impact absorption of
the floor relative to the underlying base to which it is secured in
order to reduce injuries. Accordingly a number of different floor
systems have been designed to provide an appropriate amount of
floor deflection and resiliency. Such floor systems include a
plurality of hardwood floorboards, one or more subfloor layers
supporting the floorboards, and a plurality of elastomeric pads
attached to and underlying the subfloor layer(s) for supporting the
floor system on a base in the form of a concrete or asphalt slab.
In, some cases, the base may be a pre-existing wood floor. The
floor system is anchored to the base by metal fasteners in such a
way as not to precompress the elastomeric pads when the floor
system is in an unloaded state, thereby leaving a gap of free space
between the subfloor(s) and the base with the vertical dimension of
that space being such as to allow downward deflection of the floor
under impact, thereby providing shock absorption and resiliency or
give, and reducing the amount of reaction force imparted by the
floor system to the impacting person or object.
[0003] The free space provided between the subfloor layers and the
base is also important with respect to reducing the effect of
humidity changes on the dimensional stability of the wood
components. Wood components are susceptible to absorption or
expulsion of moisture, with a resultant expansion or contraction.
The effect of humidity changes on the dimensional stability of the
floor system is reduced by the free space since the latter limits
moisture transfer between the base and the supported
components.
[0004] A number of different floor systems are known that are
designed to provide some degree of impact absorption and are
characterized by free space between the base and the subfloor
layers. One of those systems is disclosed in U.S. Pat. No.
RE37,615, issued Apr. 2, 2002 to Michael W. Niese for
"Anchored/Resilient Hardwood Floor System". The disclosure of that
patent is incorporated here by reference.
[0005] In the construction disclosed and claimed in U.S. Pat. No.
RE37,615, a plurality of mutually spaced sleepers in the form of
elongated nailing members are used to form a subfloor layer for
supporting a layer of hard wood floorboards that serve as the wear
surface. One or more subfloor layers are interposed between the
sleepers and the hardwood wear surface. The sleepers also include
compressible supporting pads, e.g., pads made of a suitable
elastomer. In the floor system disclosed in the aforesaid patent, a
fastening arrangement is used to secure the sleepers directly to
the base so that (a) the pads are not precompressed, i.e., the pads
are not compressed beyond the compression that results solely from
the weight of the flooring system components carried by the pads,
and (b) the sleepers can deflect downwardly upon impact to the
upper layer of the floor system but are restricted against upward
movement beyond the initial static position of the pads. The
fastening arrangement includes counterbored holes in the sleepers,
floor-anchoring fasteners that extend through the counterbored
holes into the base, and means for limiting the depth of
penetration of the fasteners into the base so that the downward
driving forces applied via the fasteners do not precompress the
elastomer pads. Further details of such a system are presented
hereinafter in connection with FIG. 1.
[0006] Floor systems similar to the type claimed of U.S. Pat. No.
RE37,615 are in commercial use. The foregoing patent indicates that
the floor system disclosed therein may be anchored by forcing
fasteners into predrilled holes in the base or by driving fasteners
into the base using a nail gun without any pre-drilled holes.
However, as a practical matter prior to this invention it was not
feasible or practical to anchor the sleepers to a concrete base
without first predrilling holes for the fasteners in the concrete.
Instead the usual practice has been to predrill holes in the
concrete base and use fasteners that are characterized by a
shoulder that function as a depth stop and an expansion curve
adjacent their leading end for anchoring the fasteners in the
concrete base, with the fasteners being surrounded by plastic
lubricating sleeves that sit loosely in the counterbored holes and
serve to reduce friction between the fasteners and the sleepers, as
illustrated in FIG. 9 of U.S. Pat. No. RE37,615. Typically the
lubricating sleeve has a peripheral flange at its top end and the
flange portion has a counterbore to accommodate the head the
fastener. The fasteners are driven into the predrilled holes by
manually impacting them with a hammer.
[0007] Manually driving a fastener into dense concrete without
predrilling a hole to accommodate the fastener cannot be done at
all, or at least not without having to strike each fastener
repeatedly. However, the holding power of a fastener driven into
solid concrete by repeated blows is poor. If a fastener is impacted
with sufficient force to penetrate a concrete substrate, a
so-called "ball" is formed in the concrete around the leading end
of the fastener. That ball is a densification of the concrete and
it exerts a tight grip on the fastener. However, if thereafter the
embedded fastener is impacted one or more times, the ball will be
disrupted and even disintegrate, with the result that the
concrete's grip on the fastener is weakened substantially. It is
well known in the structural fastening field that the same
phenomenon occurs when impact driving a fastener into a steel
substrate. Therefore, to maximize the holding power, a fastener
should not be hit more than once when impact driven into concrete
or steel.
[0008] Heretofore powered impact-type drivers have been used for
driving fasteners into concrete or other hard masonry substrates
for the purpose of anchoring metal components to the substrates.
However, prior to this invention use of power drivers for anchoring
the sleepers disclosed U.S. Pat. No. RE37,615 was not feasible. The
primary problem stems from -the counterbored holes in the sleepers.
The counterbores are designed to accommodate the heads of the
fasteners so they will not protrude above the sleepers where they
can interfere with the underfloor members carried by the sleepers,
particularly when the floor system is deflected downwardly under
impact.
[0009] In the case where lubricating sleeves with peripheral
flanges at their top ends are used with the fasteners, the
counterbores also serve to provide a recessed seat for the flanges.
However, the requirement that the heads of the fasteners (and also
the flanges of the lubricating sleeves when used) be recessed in
the counterbores has made it difficult to use a power driver. The
need to recess the heads of the fasteners in the counterbores
complicates attainment of the requirement that the striker or
hammer of the power driver be able to drive the fasteners deep
enough to assure a tight engagement of the fastener heads (or the
flanges of the lubricating sleeves) with the bottoms of the
counterbores, but not so deep as to preload the resilient pads. The
counterbored holes also make it difficult to center the striker or
hammer of the powered driver on the fastener head, which is an
important consideration since optimum performance of the driver
requires that its striker be readily centered on the fastener head
and the driver be positioned to drive the fastener perpendicularly
to the base. This centering problem is complicated by the fact that
in actual practice the lubricating sleeves are sized to make a
loose fit in the counterbored holes. Another factor discouraging
against use of a power driver is the requirement that the action of
the driver must not interfere with the use of fastener depth stop
means designed to prevent compression of the resilient pads, as
those disclosed in U.S. Pat. No. RE37,615.
[0010] Because of these problems there has been lacking a
satisfactory and reliable way to secure the sleepers of the form
disclosed in said patent to a concrete base without using
pre-drilled holes for the fasteners. The need to predrill holes
introduces a variety of limitations, the most significant of which
is that installation of such systems is slow and costly due to the
manual labor consumed in predrilling holes in the concrete and the
need to precisely locate the holes to assure alignment with the
counterbored holes in the sleepers, and the repeated hammering
action required to seat the fastener.
OBJECTS AND SUMMARY OF THE INVENTION
[0011] The primary object of this invention is to provide a method
and means for anchoring a hardwood floor system to a concrete base
with fasteners without the need for predrilling holes for the
fasteners.
[0012] A more specific object is to provide an improved method and
means for anchoring floor system sleepers of the type that have
counterbored holes to accommodate fasteners for anchoring the
sleepers to a concrete base.
[0013] Another object is to provide a novel and improved fastener
arrangement for anchoring hardwood floor systems.
[0014] Still another object is to provide a power driver that is
adapted for driving fasteners to anchor sleepers that have
counterbored holes for the fasteners.
[0015] A further object is to provide a novel and improved fastener
arrangement comprising a fastener and a hard plastic standoff
sleeve for the fastener that is adapted to withstand fracture by
the fastener when the fastener is impacted by the striker of a
power driver.
[0016] The foregoing and other objects of the invention are
achieved by providing a standoff sleeve/fastener arrangement for
anchoring a sleeper of the type described to a concrete base, and a
power driver for driving the fastener into the concrete base. The
standoff sleeves are sized to fit loosely (approximately {fraction
(1/32)}" to {fraction (1/16)}" clearance in counterbored holes
preformed in the sleeper. Each sleeve has a center bore for
accommodating the shank of the fastener and a peripheral flange at
its top end that is sized to fit within the counterbore. Also in
relation to the associated fastener the sleeve has an effective
length that enables it to function as a depth stop that prevents
the fastener from pre-compressing the resilient pads of the
sleeper. Each fastener has a radially projecting head at its top
end, with the head having a tapered side surface and the sleeve
having a countersink for accommodating the fastener head. In a
preferred embodiment of the invention, the taper angles of the side
surface of the fastener head and the countersink being are set so
that when the head is driven into engagement with the top end of
the sleeve, the impact force will be transmitted progressively to
the sleeve from the fastener, with the radial and axial vectors of
the impact force decreasing and increasing respectively with
increasing penetration of the fastener. The fasteners are driven
into the concrete base by means of a power driver that has a nozzle
sized to fit within the counterbores of the holes in the sleeper
and a striker bore that is sized to accept the head of a fastener
disposed in one of the counterbored holes, whereby the striker of
the driver will be aligned with the head of the fastener and the
tool will be oriented perpendicularly to the sleeper, as required
for optimum driving of the fastener into concrete. The standoff
sleeves function as a depth stop to prevent or limit preloading of
the resilient pads on the bottom of the sleeper by the driven
fasteners. Preferably but not necessarily, the drive stroke of the
driver's striker is limited so as to permit it to drive the
fastener to a depth that is sufficient to secure the sleeper to the
concrete base but not so far as to overload the resilient pads or
damage the sleeve. Other features and advantages of the invention
are set forth in or rendered obvious by the following detailed
description which is to be considered together with the
drawings.
THE DRAWINGS
[0017] FIG. 1 is a cross-sectional view in elevation of a
sleeper-type flooring system;
[0018] FIG. 2 is a fragmentary side view in elevation of the same
floor system;
[0019] FIG. 3 is a fragmentary plan view taken along line 3-3 of
FIG. 1;
[0020] FIG. 4 is a an exploded view in elevation, partly in
section, of a preferred form of fastener and sleeve provided
according to the present invention;
[0021] FIG. 5 is a fragmentary sectional view illustrating a sleeve
and fastener in ready position for a fastening operation;
[0022] FIG. 6 is a view similar to FIG. 5 showing a fastener near
the end of its travel into a concrete base;
[0023] FIG. 7 is a side view in elevation of a powered driver
modified for use in practicing the invention;
[0024] FIG. 8 is a fragmentary elevational view, partly in section,
illustrating the nozzle portion of the powered driver of FIG. 7 in
exploded relation to a fastener and sleeve used for anchoring a
floor system according to the invention; and
[0025] FIG. 9 illustrates another type of floor system with which
the invention may be used.
DETAILED DESCRIPTION OF THE INVENTION
[0026] FIGS. 1-3 illustrate a section of a floor system of the type
disclosed in U.S. Pat. No. RE37,615. The floor system comprises a
plurality of mutually spaced attachment members in the form of
wooden sleepers 2 having resilient pads 4 on their bottom side and
supporting at least one subfloor layer 6 on their top side. The
sleepers are anchored to and supported by a base 8 formed of
concrete. Overlying the subfloor layer 6 is a hard wood floor 10
which usually is made up of interlocked tongue and groove maple
floorboards. The subfloor layer(s) may take various forms, e.g., as
disclosed in U.S. Pat. No. RE37,615 and the prior art listed
therein. Typically subfloor layer 6 is formed of 4'.times.8'
plywood panels and has a uniform thickness of about {fraction (1/2
inch)}. The sleepers 2 typically have a cross-sectional height of
about 1.5 inch, and a width of about 2.5 inch, and a length of
either 4 or 8 feet. The sleepers are usually spaced apart about 12
inches, although that spacing may vary depending upon their width.
The foregoing dimensions are not critical, and hence sleepers
having a different height, width, length and spacing may be
used.
[0027] The pads 4 are molded from an elastomeric material in order
to provide resiliency, vibration dampening and shock absorption for
the floor system. The pads may take various shapes without
affecting the invention. Thus, for example, the pads may be as
illustrated in U.S. Pat. No. 5,388,380, issued Feb. 14, 1995 to
Michael W. Niese and U.S. Pat. No. 6,367,217, issued Apr. 9, 2002
to Michael W. Niese et al. The pads may be solid or may be formed
with hollow internal volumes or spaces to better permit the pads to
deflect in the vertical direction immediately upon impact to the
hard wood floorboards 8. The pads are sized to provide a space of
predetermined minimum height between the sleepers and the
supporting base, typically a height in the range of about 0.5 to
about 0.75 inch, under the static weight of the floor system.
[0028] Each sleeper member is provided with at least one and
preferably two through bores 14 to accommodate fasteners 16 and
standoff sleeves 18 as hereinafter described. A counterbore 20 is
coaxial with each bore on the top side of the sleeper, so that each
bore has a relatively small diameter bottom section and a
relatively large diameter top section. The bottom end of each
counter bore has a flat annular surface 22 (FIG. 6).
[0029] According to this invention, the fasteners 16 are formed
with a head 24 having a conical side surface and a flat top surface
and a shank that has a pointed tip. Referring to FIGS. 4 and 6,
preferably the shank is stepped so as to provide a relatively large
diameter upper or trailing section 26A and a relatively small
diameter lower or leading section 26B, with a short tapered
transition section 26C. By way of example but not limitation, the
fastener may have an overall length of 2.25 inch, a maximum head
diameter of 0.5 inch, an overall shank length of 2 inches, a
transition section (26C) length of {fraction (1/32)}-{fraction
(1/16)} inch, and diameters of 0.200 inch and 0.190 inch for shank
sections 26A and 26B respectively. The larger diameter section 26A
serves to provide column strength to the fastener so that it will
not buckle when it is impacted against the concrete base by the
powered driver as described hereinafter. The smaller diameter
section 26B and its pointed tip 27 facilitate piercing of the dense
concrete; the tapered transition section facilitates penetration of
the concrete by the leading end of shank section 26A. It is
preferred, but not essential, that the shank section 26B have a
plurality of shallow helical grooves located rearwardly of the
point tip section, as indicated at 28 in FIG. 6, to facilitate
penetration of the dense concrete under the impact force of a
powered driver according to this invention. In order to assure
penetration without bending, the fasteners are preferably made of
an alloy or special high carbon steel and heat treated to HRc 53/56
hardness.
[0030] The standoff sleeves 18 may be made of various materials.
Preferably they are made of a high density plastic such as
Delrin.RTM. or a high impact plastic such as a high density
polyethylene. The sleeves have a cylindrical shape and are
characterized by a center bore 30, and a peripheral flange 32 at
one end, hereafter caller the top end. Additionally the top end of
each sleeve has a conical countersink 34 for bore 30. The height of
flange 32, i.e., its dimension measured longitudinally of the,
sleeve, is less than the depth of the counterbores 20. The overall
length L1 of the sleeve is set so as to be less than the distance
between the bottom surface 36 (FIG. 1) of subfloor 6 and the upper
surface of base 8 after the floor system has been anchored to the
base without precompressing pads 4. Also the length of the portion
of each sleeve between flange 32 and its bottom end surface,
represented as L2 in FIG. 6, is equal to the combined vertical
distance between the annular surface 22 of counterbore 20 and the
upper surface 9 of base 8 after the floor has been anchored to the
base without precompressing pads 4. Sleeves 18 are formed with the
diameter of center bore 30 equal to the diameter of shank portion
26B, so that when the fastener is inserted into the sleeve, it will
be held up by shank section 24A being gripped by surface-to-surface
contact with the sleeve in bore 30 or by an interference fit
between bore 30 and shank transition section 26C, with the result
that the head of the fastener will be in a raised or upwardly
projecting position relative to the top end of the sleeve.
Preferably the sleeve and fastener are sized so that when the
sleeve 18 is inserted in a hole 14 with its flange resting on the
bottom surface 22 of counterbore 20, and a fastener is inserted in
the sleeve, the head and a substantial portion of the shank portion
26A of the fastener will project above the upper surface of the
sleeper, as shown in FIG. 5. As a minimum, at least the head of the
fastener should project above the head of the sleeper in order to
facilitate alignment of the powered driver used to propel the
fastener into a concrete base. Preferably also fastener 16 and
sleeve 18 are sized so that when the fastener is inserted into
sleeve its pointed tip 27 is even with, or just short of being even
with, the bottom end surface of the sleeve.
[0031] A suitable form of powered driver is disclosed in U.S. Pat.
No. 5,645,208, issued Jul. 8, 1997 to Harry M. Haytayan for
"Pneumatic Fastening Tool With Safety Interlock". The disclosure of
that patent is incorporated herein by reference. With reference to
the drawings of that patent, the driver illustrated therein
includes a nozzle member 6 that is provided with (1) an
axially-extending bore 112 that accommodates a hammer 68 (also
identified by persons skilled in the art as the "striker"), (2) a
side entry port for fasteners carried in strip form by a magazine 8
that is attached to the nozzle member, and (3) a second
axially-extending bore 118 that accommodates a spring-biased
valve-actuating safety rod 120. Such a device is capable of driving
fasteners into concrete with a single impact without any
predrilling, with the fasteners having a holding power in the
concrete in excess of 1000 lbs., partly as a result of the ball
phenomenon described above. Pneumatic drivers embodying the design
disclosed in U.S. Pat. No. 5,645,208 are available commercially
from Pneutek, Inc. of Hudson, N.H. One such driver is Pneutek Model
PT 1100.
[0032] FIG. 7 illustrates a pneumatic driver 40 of the type
disclosed in U.S. Pat. No. 5,645,208 and exemplified by Pneutek
Model PT 1100, but modified to incorporate a nozzle according to
the requirements of the present invention. For the purposes of this
invention, a fastener-carrying magazine is not required.
Consequently the nozzle does not have a side entry port for
fasteners. The bottom end of nozzle 42 has a circular configuration
with an outside diameter that is smaller than the diameter of the
counterbores 20. Preferably the o.d. of the bottom end of the
nozzle is about 0.19 inch less than the diameter of counterbores
20. Referring to FIG. 8, the nozzle has an axial bore 44 for the
striker or hammer (not shown) of the driver. Bore 44 is coaxial
with the center point of the nozzle's circular end face 46 and has
a diameter that exceeds the maximum diameter of fastener head 24 by
a small amount, preferably by about {fraction (1/32)} to about
{fraction (1/16)} inch. The nozzle has another axially extending
bore 48 that accommodates the safety rod 50 of the driver. Bore 48
is eccentric to the center point of end face 46, being formed in a
portion of the wall of the nozzle that surrounds bore 44. Rod 50 is
biased downwardly by a spring 52 so that normally it projects
beyond the end face 46 as shown in FIGS. 7 and 8. Rod 50 is
equivalent to and serves the same function as the safety rod 120
disclosed in the aforesaid patent.
[0033] Still referring to FIGS. 7 and 8, the bottom end of the
nozzle is provided with a circular recess 56 that is coaxial with
bore 44. Recess 56 functions as a counterbore for bore 44. The
annular surface 58 that forms the inner end of recess 56 is flat.
Recess 56 has a diameter that is slightly greater than the o.d. of
flange 32 of sleeves 18, preferably about {fraction (1/32)} to
about {fraction (1/16)} inch greater. Preferably the depth of
recess 56, i.e., the dimension measured parallel to bore 44, is the
same as that of flange 32, but it may differ therefrom by a small
amount, e.g., plus or minus {fraction (1/32)} to {fraction (1/16)}
inch. As noted above, the diameter of striker bore 44 must be large
enough to readily accommodate the fastener head 24 but not so large
as to introduce a degree of lateral play that make its difficult to
locate the nozzle in a counterbore 20 or will locate the striker
axis off center with respect to the fastener head. The length of
the striker (not shown) is set so that when the driver is fired,
i.e., operated, the striker will move through its downward stroke
far enough to cause the end of the striker to be flush with or
protrude beyond annular surface 58 of nozzle recess 56 by
approximately {fraction (1/32)} inch, whereby to cause the head of
the fastener to be seated in countersink 34 and to force the sleeve
into tight engagement with base 8.
[0034] With the foregoing apparatus, anchoring of floor systems of
the type described in U.S. Pat. No. RE37,615 is greatly
facilitated. To anchor a sleeper as herein described and
illustrated, a sleeve 18 and a fastener 16 are inserted in one of
the holes 14 (FIG. 5). Holes 14 and sleeves 18 are sized so that
holes 14 are approximately {fraction (1/32)}" to approximately
{fraction (1/16)}" larger than the o.d. of the sleeves. The sleeve
may be inserted first, followed by the fastener; alternatively and
preferably, a fastener 16 and a sleeve 18 are assembled together as
shown in FIG. 5 and then inserted into a hole 14. In either case,
the bottom end of the sleeve will touch the upper surface 9 of base
8 and the bottom side of flange 32 will engage or nearly engage the
surface 22 of the sleeper. Then nozzle 42 of driver 40 is placed
over the sleeper so that the head of the fastener extends up into
striker bore 44 and flange 32 of sleeve 18 resides in recess 56.
When the bottom surface 46 of the nozzle engages the upper surface
of flange 32, safety rod 50 will be depressed, activating the
driver for operation by the user. With the driver connected to a
source of pressurized air, the driver is fired by squeezing its
trigger 60. When the driver is fired, the striker of the driver
will impact the head of the fastener at a high velocity and with a
great downward force, causing the fastener to penetrate concrete
base 8. The striker of the driver forces the fastener into the
concrete far enough (approximately 1" to 11/2") to cause its head
24 to be seated in countersink 34 and to lock sleeve 18 tight
against the base 8. However, because of the depth-limiting action
of the sleeve on the fastener, the fastener is not driven into the
concrete so far as to precompress the resilient pads. Further
assurance that the fasteners are driven into the concrete the
correct amount is provided by the fact that the stroke of the
striker is limited as described above. The limited stroke of the
striker also eliminates any possibility that the striker will crush
the sleeve.
[0035] FIG. 6 also illustrates a preferred relationship of fastener
head 24 and counterbore 34. Although satisfactory results are
obtained when the angle of taper of the side surface of the
fastener head 24 is the same as that of countersink 34 of sleeve
18, it is preferred that the taper angle of the countersink be less
than that of the fastener head measured relative to the center axes
of the sleeve and fastener. Preferably the countersink has a taper
angle of about 60.degree. and the side surface of the fastener has
a taper angle of about 82.degree., as indicated in FIG. 4. The
advantage of that arrangement is explained with reference to FIG. 6
which illustrates the position of the fastener as its head first
engages the sleeve under the driving force of the striker of driver
40. The first contact between fastener head 24 and the countersink
surface 34 is limited, consisting essentially of a circumferential
line contact with the force of the fastener head comprising both
radial and axial vectors. As the fastener is driven further down
into the sleeve, its head deforms the countersink portion of the
sleeve radially so as to permit the entire inclined side surface of
the head to contact the countersink surface. Essentially the area
of contact between the fastener head and the sleeve increases with
increasing penetration of the fastener. The difference in taper
angle limits the initial contact area and also allows the fastener
to move down vertically relative to the sleeve at the beginning of
the stroke, thereby limiting the magnitude of the initial shock of
impact experienced by the sleeve and consequently reducing the
possibility of the sleeve being shattered by the initial impact.
This is an important consideration in the case of hard plastic
sleeves, since fracture of the sleeve will frustrate the
requirement that the compressible pads not be preloaded.
[0036] The invention is not limited in its application to floor
systems of the type wherein the floor attachment members are in the
form or nailing strips or sleepers that carry the resilient pads.
Thus, for example, the invention also is applicable to a hardwood
floor system of the type disclosed in U.S. Pat. No. 6,367,217,
issued Apr. 9, 2002 to Michael W. Niese et al. for "Sleeper
Assembly For Resilient Hardwood Floor System". FIG. 9 illustrates
that system. In this case the system comprises an upper floor wear
surface in the form of a plurality of interlocked floorboards 60
supported in spaced relation to the dense supporting base 62 by
spaced rows of substructure assemblies 64. Each substructure
assembly comprises an elongated panel 66, a pair of spaced rows of
compressible pads 68 attached to the bottom surface 70 of the panel
adjacent its opposite edges, and corresponding pair of rows of
nailing strips 72 secured to the top surface 74 of the panel above
the rows of pads. The floorboards are nailed to the substructure
assemblies and the latter are secured to the base by fasteners 76
that pass through holes in the panels and are secured in holes in
base 62. Each fastener is provided with a shoulder 78 intermediate
its opposite ends that functions as a depth stop to limit the depth
of fastener penetration into the base and thereby prevents
precompression of pads 68 by the downward driving forces applied by
the fasteners as they are driven into the base, with pre-drilled
holes being required in the case of a concrete base. A lubricating
sleeve 80 is disposed in each of the holes in panel 66 in
surrounding relation to the fasteners and has a flange 82 that
overlies panel 66. The head 84 of fastener 76 is seated against
flange 82. The sleeves project down through panel 66 only a limited
distance and do not contact the base when the fastener is driven
into the base to the extent allowed by depth stop 78. The nailing
strips 72 provide an air space 86 between the upper surface 74 of
panel 66 and the lower surface 88 of floorboards 60.
[0037] Since substructure assemblies of the type shown in U.S. Pat.
No. 6,367,217 are installed first before the floorboards 60 are
nailed in place, the present invention makes it possible to anchor
them to a hard concrete base without any need for predrilling holes
in the base. This is accomplished by replacing fasteners 76 and
lubrication sleeves 80 with fasteners 16 and sleeves 18 as
illustrated in FIGS. 1 to 6, with the lengths of the fasteners 16
and 18 being adjusted to allow the sleeves to function as depth
stops and the fasteners to penetrate the base to a depth sufficient
to assure that the heads of the fasteners will force the sleeves
into tight engagement with the base without precompressing the
resilient pads. As with the sleeper type construction shown in FIG.
1, the sleeves 18 and the holes in each panel 66 are sized so as to
provide a clearance of approximately {fraction (1/32)}" to
{fraction (1/16)}". In both types of floor constructions, the
reason for such clearance is to prevent floor squeaking as the
floor is subjected to loading and unloading forces.
[0038] Although it is preferred to use fasteners with step-down
shanks as shown in FIGS. 4-6, the invention may be practiced with
fasteners that have straight shanks, e.g., a shank having a
substantially constant diameter except for a pointed leading end.
In such case it is preferred that the shank diameter be the same as
that of bore 30 so that the shank makes a tight fit in and is
gripped by the sleeve. Also, it is preferred that the fastener and
sleeve be pre-assembled with the pointed tip of the fastener
substantially even with the bottom end of the sleeve.
Alternatively, the shank diameter may be slightly smaller than bore
30, in which case the sleeve 18 may be inserted in hole 14 first,
and then the fastener may be inserted into bore 30 with its tip
engaging the underlying base 8.
[0039] As used herein in relation to resilient support pads 4, the
terms "precompressing" and "precompression" are synonymous with
"preloading" and are intended to embrace the situation where the
pads are essentially not compressed at all by the fasteners, and
also the situation where the pads are compressed somewhat as a
consequent of the fastening operation but are still capable of
further compression to the extent required to allow the floor
system to deflect downwardly when impacted within the operating
limits contemplated by the parameters of the system. In this
context it is recognized that the support pads 4 and 68 are
compressed by the weight of the floor components, and such
compression is not to be construed as coming within the scope of
the term "precompression".
[0040] The advantages of the invention are obvious and significant.
No predrilling of the concrete base is required in order to anchor
floor systems with fasteners. Furthermore the invention eliminates
the need to use fasteners characterized by a shoulder that
functions as a depth stop and fasteners having expansion curves for
locking them in pre-drilled holes in a concrete base. The driving
of the fasteners is rapid, with the manual labor limited to
inserting the sleeves and fasteners in holes in the wooden
attachment strips, and positioning and firing the driver.
Additionally pneumatic drivers of the type described herein are
reliable and easy to use, and a nozzle as shown in FIG. 8 is
capable of withstanding the wear and tear encountered in the field.
Overall the invention provides a tremendous saving of cost and time
while providing anchor strengths far in excess of what has been
achieved heretofore in the installation of hardwood floor systems
on concrete slabs. Still other advantages will be evident to
persons skilled in the art. Moreover, those skilled in the art will
readily comprehend the various modifications to which the invention
is susceptible.
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