Note: Descriptions are shown in the official language in which they were submitted.
CA 02714807 2010-09-16
FURNITURE LEG FLOOR PROTECTOR
DESCRIPTION
RELATED APPLICATIONS
[0001] This application is related to United States Patent Serial Application
No.
12/082,054 filed April 8, 2008, the entire contents of which are incorporated
herein by reference.
This application is also related to United States Provisional patent
application number (Attorney
docket number AP 1537USP) the contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to furniture leg floor protectors, and, more
particularly,
floor protectors for use with legs of chairs, tables, stools, sofas, room
dividers, or any other
furniture having legs (hence feet) to protect the floor when the furniture is
moved, whether by
sliding or rocking.
BACKGROUND OF THE INVENTION
[0003] Furniture leg floor protectors have been in use for many years to avoid
damage to
the floor when a piece of furniture is moved, They also reduce noise in the
classroom where
children move their desks and chairs around often making an irritating noise.
(0004] Some known floor protectors for furniture legs comprise a disk of
synthetic
plastics material, or metal, which can be fixed to the end of the leg by
adhesive or a screw.
Attached to the underside of the disk is a pad of felt or other suitable
protective material which
contacts the floor. For example, US 2005/0003723 (Brouard et al.) discloses
floor protectors for
fastening to the underside of the foot of the leg by adhesive or by a hook-and-
loop fastener (e.g.,
Velcro), so that it can be replaced more easily. US 2008/0148522 (Beshore), as
another
example, discloses a three-part floor protector which comprises an inverted
cup for securing by
its base to the furniture leg by means of a screw. Engaged in the inverted cup
are a glide of non-
abrasive synthetic plastics material, an interposed resilient washer. US
2007/0234507 (Vorpahl)
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discloses yet another example in the form of a glide assembly which has
interchangeable hard
and soft bases and several attachment devices which can be adapted to the foot
of the furniture
leg and the type of floor.
[0005) Sometimes, it is not practical or desirable to fasten the floor
protector using a
screw fastener or adhesive, For metal or plastics furniture legs having an
enlarged foot portion,
perhaps in the form of a disk or toroid, or even an adjustable foot or glide
fastened by a screw, it
is known to use a slip-on floor protector in the form of a unitary boot of
rubber or synthetic
plastics material which fits over the foot/glide and grips its upper surface,
The boot may itself
contact the floor or may carry a pad of felt or other protection material.
Examples of slip-on
floor protectors are disclosed in US 2,865,133 (Hoven et al.), US 6,405,982
(Ferencz), and US
6,754,934 (Shifller).
[0006] It is also known to use a slip-on floor protector which is generally in
the form of a
ball with a slit in the top, as disclosed, for example, in US 2007/0220703
(LaPointe et al.). The
end of the furniture leg is inserted into the ball so that its foot rests on
the interior of the bottom
of the ball and the sides of the slit grip the furniture leg.
[0007] Because these slip-on floor protectors are relatively short, they may
become
dislodged relatively easily, especially when used in schools where chairs may
be rocked as well
as dragged. Also, the boot or ball may be considered to be unsightly.
[0008] It is known to use a floor protector having not only a boot portion to
fit around the
foot of the leg but also an integral tube which will extend upwards along the
leg and grip the
surface of the leg above the foot. US 2008/0179471 (Verdelli), for example,
discloses a tube
which is secured to the furniture leg by means of elastic bands or by ribbon
or string tied around
it. US 2008/0209686 (Lang) also discloses a floor protector secured to the
foot or leg by a tie.
In one embodiment, the protector has a tube closed at one end (which contacts
the floor) and a tie
wrapped around portions the tube near its other end to fasten it tightly to
the leg. In an alternative
embodiment, the tie passes through upstanding flanges of a boot to draw them
closed over the
upper surface of the foot, The use of ties may not be acceptable because they
may come undone
and may be unsightly.
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[0009] Some floor protectors rely, at least primarily, upon elasticity of the
sleeve to grip
the leg of the furniture, For example, US 7,124,986 (Bailey) discloses a floor
protector
comprising an elastomeric sleeve with one end closed, at least partially, to
form a bottom to
which is glued or stitched a pad of felt or other protective material. The
sleeve can be stretched
to fit onto the furniture leg, US 2004/0123421 (Bushey) discloses a floor
protector comprising a
hemispherical base and a sleeve for fitting around the furniture leg. The
sleeve has resilient
projections in the form of splines, flutes or leaves, which extend radially
inwardly to grip the leg.
These projections may complicate manufacture yet not provide adequate grip,
especially when
the protector has been in use a long time and repeated flexing and aging have
reduced the
elasticity of the sleeve. Similarly, United States Publication No.
2004/0123421 discloses a floor
protector with a corrugated sleeve having folds therein to increase friction.
it would appear,
however, that the complexity of the molding process could make this option
uneconomical.
[0010] United States published patent application No. 2005/0115022 (Desmarais -
present inventor) discloses a floor protector having a sleeve with internal
splines to grip the leg.
The problem of stretching and enlargement of the sleeve, causing it to loosen
was addressed by
means of a flexible coupling between upper and lower portions of the sleeve,
allowing the leg to
tilt while the pad beneath the foot of the leg remained flat upon the floor.
Nevertheless, this
approach too is not entirely satisfactory because it entails a rather
complicated, hence costly,
moulding configuration.
[0011] The trade-off between ease of installation of a floor protector having
an
clastomeric sleeve and the security of the grip between the sleeve and the
furniture leg,
especially after the furniture has been dragged or tilted repeatedly during
normal usage, was
addressed in the present inventor's United States published patent application
No. 2008/0258023,
which discloses a floor protector having a sleeve which is more elastic at the
top than at the
bottom. This upper portion can be stretched enough to allow it to be rolled
outwards, the
leg/foot inserted into the less elastic lower portion, and the upper portion
unrolled onto the leg.
Rolling up the stretchable upper sleeve portion facilitates installation,
while the stiffer lower
sleeve portion firmly grips the lower portion of the leg and provides good
stability of the floor-
engaging pad. Nevertheless, this arrangement may not be entirely satisfactory
if fitted to heavy
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furniture or, in the case of an occupied chair, ti1it l and/or dragged,
subjecting the sleeve to
excessive stress,
[0013] An object of the present invention is to overcome or at least mitigate
the above-
described deficiencies of such known floor protectors, or at least provide an
alternative furniture
leg floor protector which combines case of installation with security once it
has been installed.
To this end, ombbodiments of the present invention eutploy shrinkable tubing,
fbr example, beat-
shrink tubing, to secure the floor protector directly or indirectly to the
leg.
[0014] In this specificaon, the team "unshrunk" tube/tubing will be used M
describe the,
uuudition of the tube/tubing before it has been. shrunk, and the word
"shrunken" will be used to
describe the tube/tubing after it has been shrunk. This does not preclydie,
however. the
tubeJtubing having been shrunk partially down to the 'uagn mk" size.
[0015] According to one aspect of the present invantiop, there is provided a
floor
protector adapted for use with funiture having at least one leg with a foot
portion, the floor
protector comprising a tube of shrinkable material that can be slttunk by
application of hest, or
other suitable means, the tube having at normal tcrnperaturec a predetermined
unshrok MSS.
wtional size large enough to permit the tube to receive said foot portion and
a shrinkage rate
sufficient for the tube to be sluunkai to a cross-sectional size that is
smaller than the fbot portion
so that, when the tube is placed over the foot portion and shrunken by
application of a said heat
or other means, the tube will conform and adhere to the underlying toot
portions and secure and
seams the floor protector to the foot portion.
[0016] According to another aspect of the present invention, there is provided
a method
of installing a floor pmtector onto a fuut portion of a furniture leg,
comprising the steps of fitting
over the foot portion a tube of shrinkable material having a predetermined
unshrunk cross-
sectional size large enough to receive the foot portion, the shrinkable
material having a shrinkage
ratio sufficicnt for the tube to be shrunken to a size smaller that a =8s-
sectional size of the foot
portion, and shrinking the tube by application of heat or by other suitable
means to cause the tube
to shrink at least until the tube has conformed to the underlying surface of
the foot portion to
Such an extent as to secure to floor protector to said foot portion.
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[0017] Preferably, the shrinkable tube is made of heat shrink material, i.e. a
thamnplustic material whicb shorties when heated. it is known to use heat-
shrink tubing in the
dectrieal industry around connections betweou electrical conductors and
between electrical
conductors and terminals, to provide insulation, abrasion resistance and
environmental
protection. Suitable heat-shrink materials may shrink to as little as one
third or one quarter of
their original size and may shritdc at temperatures which can be obtained
using a heat source that
is relatively readily available, such as a small butane torch, an elect tttsad
hot air hest gun, a paint-
stipper or a hair dryer. Gcuerally, commercial hand-held hair driers would be
prefwcd because
domestic hair dryers operate at lower air temperatures than cormucrcial hair
driers, which limits
their use with heat shrink materials that are commercially available at this
time. Nevertheless,
use of a domestic hair dryer or other heat source is not precluded if it can
provide the required
.
How of air at a sufficiently high temperature
1001$) In embodiments of either aspect otthe invention, at least part of the
interior of the
tube may be provided with an adhesive so that, once the tube has bt n fully
shrunk, the adhesive
bonds the tube to the foot portion and provides additional security against
the fluor protector
being dislodged, Where the nthe wmpriscs heat-shrink material, the adhesive
may be heat-
sensitive (hot-melt) adhesive arranged to melt at a temperature similar to
that required to shrink
the tube. the hot melt adhesive being melted (activated) centeimpurancously
with the shrinking of
the tube, i.e., using the same heat source.
(0019] Preferably, the shrinkable tube is installed onto a toot portion having
a non-
urrifiun profile, Le., having lateral protrusions, so that, once the tube has
been shrunk, the tube
conforms at least partially to the protrusions and provides mechanical
resistance to movement in
the direction of the tubular axis tat remove the floor protector.
(00201 In preferred embodiments of either aspect of the invention the
unabrunken the is
partially or completely closed at one end which carries a pad of protective
material, the
unshnrnken tuba being greater in cross-sectional size than the foot portion of
the furniture leg
and having a length predetermined such that when the tube has been shrunken
onto the furniture
leg foot portion, a desired friudoual force between the tube and the leg or
foot portion is
sufficient to bold the tube and pad onm the foot portion,
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(0021] Preferably, the pad is embedded partially into the material of the
closed end of the
tube, the material of the tube infusing interstices at an upper (in use)
surface of the pad. Such
embedding of the pad may be attained by moldipg the tube onto the pad during
moulding of the
floor protector. In preferred embodiments, at least the uppermost (in use)
portion of the pad
comprises fibrous material, e.g. wool felt.
[0022] Preferably the shrinkable tube material is selected, both in terms of
its shrinkage
characteristics and dimensions, so that the shrunken tube may conform closely
(tightl)'?) to the
exterior of the leg and/or foot portion both to provide a desired gripping
force and to avoid, at
least to some extent, an unsightly result. It may be transparent so as to be
less noticeable.
Suitable shrinkable materials include polyurethane, polyolefln, polyolefin,
fluoropolymer (such
as FEP, PTFE or Kyaaim), PVC, neoprene, silicone elastomer or Viton .
(0023] Further features and advantages of floor protectors embodying the
present
invention will be set out in the following description of preferred
embodiments of the invention,
taken in conjunction with the accompanying drawings, which descriptions
provided by way of
example only.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
[0024] Figures 1 A, I B, 1 C and I D are partial perspective views
illustrating installation
of a floor protector onto the bi-conical foot portion of a furniture leg, the
floor protector
comprising a shrinkable tube having at one end a protective pad; and
[0025] Figures 2A, 2B, 2C and 21) are partial perspective views corresponding
to Figures
IA, 1B, IC and ID, respectively, but illustrating installation of such a floor
protector onto a
stright-sided foot portion of a furniture leg.
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DETAILED DESCRIPTION PREFERRED EMBODIMENTS
[0026] Installation of a shrinkable floor protector onto the foot portion of a
furniture leg
will now be described with reference to Figures 1A, 113, IC and 1 D. Figure IA
shows a
lowermost part of a furniture leg 100 that tapers downwards to end in a bi-
conical foot portion
101 formed by an upper truncated conical section 101A which, as shown, will be
upright use,
and a lower truncated conical section 101B which is shown inverted, as in use.
The conical
sections are joined at their respective maximum diameter bases. A generally
part-spherical
intermediate portion 102 connects the upper conical section 101A to the
tapered leg above it.
The truncated end of the lower conical section 101E normally rests upon the
floor (not shown)
and if not protected, may leave marks.
[0027] Figure 1B shows a cup-shaped floor protector 103 placed beneath the
lower
conical section 101E of foot portion 101. The floor protector 103 comprises a
cylindrical tube
104 of heat-shrink material having a pad 105 of protective material, for
example wool felt, at one
end. The pad 105 is shown closing the end of the tube 104 but it is not
essential that it do so
completely, providing it is securely attached to the end of tube 105, Before
shrinking, the
diameter of unshrunk heat-shrink tube 104 is greater than the maximum diameter
of the conical
sections 101A/101B which are received in the tube 105. The length of the heat-
shrink tube 104
is significantly greater than the height of the lower conical section 101E so
that the application of
sufficient heat to the uppermost part of the heat-shrink tube 104 causes the
uppermost part to
shrink until it securely grips the inclined surface of upper conical section
101A,, as shown in
Figure 1C.
[0028] In this case, the difference in diameter between the maximum and
minimum
diameters of the lower conical section 10113, and the diameter of the pad 105,
mean that it is not
practical for the shrunken heat shrink tubing 105 to conform to more than a
small part of the
surface of the lower conical section 101B. Nevertheless, appropriate heating
of the lowermost
part of tube 104 causes it to reduce in diameter and securely grip the pad 105
and the upper part
of the surface of lower conical section 101 B to provide a degree of stability
to the protection pad
105 without damaging the joint between the pad 105 and the and of tube 104,
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(0029] The grip between the heat-shrink tube 104 and the foot portion 101 may
be
eabanced by applying adhesive, preferably to the interior surface of tube 104
before installation,
conveniently during manufacture,
[0030] An advantage of using heat shrink material for tube 104 is that, as it
shrinks, it
will generally conform itself to the shape of the foot portion onto which it
is being fitted, and
grip the surface of the foot portion with significant friction. Consequently,
it is envisaged that
the same floor protector 103 may be fitted upon legs or foot portions having
uniform surfaces
and non-circular cross-sectional shapes. Thus, by way of example, Figures 2A,
2B, 2C and 2D
are views corresponding to Figures 1 A, I B, I C and I D but of the same floor
protector 103 being
installed onto the foot portion 201 of a square-section furniture leg 200
which has straight
parallel sides. The floor protector 103 is similar to that of Figures 1A - I D
and, when shrunken
onto the foot portion of leg 200 as shown in Figure 2D, relies upon friction
between the tube 104
and the underlying surface of foot portion 200 to hold the pad 105 securely
onto the end of leg
200 and prevent it from dislodging in normal use of the object/furniture. In
this case, it may be
especially desirable to provide adhesive on the interior surface of tube 104,
as described above
with respect to tube 104 shown in Figures lB-ID. The adhesive may be a heat-
sensitive (hot-
melt) adhesive preferably with a melting temperature similar to that used to
shrink the tube 104
so that the activation of the adhesive will take place while the tube 104 is
being shrunk onto the
foot portion 101, i.e., using the same heat source,
[0031] In each of the foregoing embodiments of the invention, the material of
the pad
105 may be chosen according to the particular situation in which the
object/furniture will be
used. For example, wool felt may be preferred where the furniture is likely to
be used on
hardwood flooring, or where noise may be a problem, as in schools. Wool felt
or other fibrous
material also may be preferred for its ability to allow adhesive to penetrate
into the interstices
between fibers and improve adhesion and strength. The radial end surface of
tube 104 and/or
the end portion of tube 104 (if it extends around the pad 105) may be provided
with, indentations,
perforations or other formations to improve adhesion of the pad 105.
[0032] Preferably, the upper (in use) surface of the pad 105 has interstices
into which the
hot thermoplastic material (forming the end of tube 104) can flow during
moulding, the pad 105
being used like a mould insert, (It has been found that 100% wool felt is
suitable when the
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thermoplastic material is PVC or polyolefin). Once the thermoplastic material
cools and sets the
pad 105 remains permanently embedded, partially, in the end of tube 104. It
should be noted
that, when such partial embedding is used, the end of the tube need not be
completely closed.
An annular end surface can provide sufficient area to embed and attach the pad
105 securely.
[00341 Heat-shrink materials presently readily available may be shrunk using
hot air
supplied by, for example, small butane torch, a heat gun, an electric hot air
paint stripper, a
commercial (high temperature) hair drier, or other suitable heat source, Use
of a domestic hair
dryer or other heat source is not precluded if it can provide the required
flow of air at a
sufficiently high temperature. The choice of heat source will depend upon the
characteristics of
the heat shrink material and the sizes of the floor protector and furniture
leg foot portion. Heat-
shrink tubing is available in a variety of sizes and chemical compositions,
with different heat
requirements. Some examples are: polyolefin, fluoropolymer (such as FEP, PTFE
or Kynar),
PVC, neoprene, silicone elastomer and VitonTm.
[0035] A specific example of such a floor protector would be a 2" diameter by
2" length
cylindrical shaped sleeve composed of shrinkable clear PVC with a shrink ratio
2:1 easily
conforming to square funiture leg of 1-1/4" width. In this case an adhesive
used inside the floor
protector would have a composition resistant to plasticizers, based on
polyamides in order to
glue the PVC. The felt pad at the bottom could be 1/4" thick by 2" in diameter
or less if we
want the felt to match the shrunken size rather than the unshrunken size.
[0036] It should be appreciated that heat-shrink material used for insulating
electrical
conductor splices and terminations is tubular and formed by extrusion, which
requires lower
temperatures (e.g. about 80 C) than injection moulding temperatures (e.g. 100-
150 C) because
the extruded tube must be firm enough to pull while the injected plastics
material must be
viscous enough to flow. However it is possible to injection mold PVC and
polyolefin using a
lower injection temperature and higher injection pressure, especially with
simple shapes such as
a small cylindrical shape (as in embodiments of the invention) where the
molten material has a
simple path to follow in order to fill the mold.
[0037] An advantage of floor protectors embodying the present invention is
that they do
not rely primarily upon elasticity of the heat-shrink material of tube 104
being sufficient for it to
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be stretched during installation and then grip the furniture leg elastically
to retain the floor
protector in place; rather, embodiments of this invention rely upon the
unsbrunk heat-shrink
material tube 104 being sized to fit easily onto the foot portion, which
allows easy installation,
and being capable of being shrunk to such an extent that it conforms closely
to the underlying
surface of the furniture leg foot portion, whereupon inherent tackiness or
striation of the heat-
shrink material provides good frictional engagement. The security of the
installation is further
improved where the contour or profile of the underlying leg surface is not
straight, so
conformance of the shrunken tube to the foot portion provides additional
mechanical locking,
particularly since the more the heat-shrink material is shrunk, the more
inelastic it becomes; and
yet further improved by using an adhesive.
[0038] It is envisaged that the shrinkable tube 104 could be shrunk onto both
pad 105 and
foot portion 101, in which case the pad 105 might be stepped so that a central
portion protrudes
beyond the end of the tube to contact the floor when the floor protection is
in use.
[0039] It is preferred, however, to mould the floor protector 104 as a single
unitary
component, similar to heat-shrink and caps for insulation electrical conductor
ends, but with the
pad 105 embedded in the heat-shrink material during moulding.
[0040] There is a trade-off between the thickness and shrinkage ratio of the
heat-shrink
material, which thickens as it shrinks. A shrinkage ratio of 2:1 is preferred
so that the final
thickness of tube 104 is not too great. Nevertheless, a shrinkage ratio of 3:1
of 4:1 might allow a
single size of floor protector to be used with a wider range of sizes of foot
portion 101 and would
likely be clearer (when transparent),
