Note: Descriptions are shown in the official language in which they were submitted.
CA 02437147 2003-08-08
DRAWER SLIDE
Field of the Invention
The present invention relates to drawer slides for use in furniture and
fixtures,
woodworking, industrial and electronic equipment, and more specifically to
drawer slides
that use low friction polymers applied to metal or plastic slide members to
facilitate
sliding movement of the slides relative to one another.
Background of the Invention
Most drawer slides use caged ball bearings to reduce sliding friction between
the slide
members during extension and closure of the slides corresponding to opening
and
closing movement of a drawer. Ball bearing drawer slides however suffer from a
number
of disadvantages. These include cumbersome assembly involving many components
in the manufacturing process, uneven wear of the ball bearings, caused by
lateral
wobble and uneven normal loading, and alignment is critical in relation to the
ball
bearings and the slides. The caged ball bearing assembly only runs about one-
third of
the length of the actual load bearing arm. Because of this one-third ratio,
the ball
bearings need very close tolerances between the steel guides. The steel tracks
themselves must be precisely aligned with the caged ball bearings which also
adds to
cost. Once the bearing becomes worn, the slides can suffer from "lateral
wobble". The
steel tracks themselves must be manufactured to close tolerances for balanced
movement, and the tracks are normally complicated in their geometric
configuration,
meaning that they must be stamped, which is a more expensive manufacturing
process
compared to cold rolling. The slides must be wide enough to accommodate all of
the
components comprising a current caged ball slide. This can prevent furniture
manufacturers from stream-lining their designs so that the slide components
are ideally
hidden. And as well, dust, dirt, rust and humidity can further reduce the
efficiency of ball
bearing slides over time.
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Summary of the Invention
It is an object of the present invention to provide improved slides that
overcome and
mitigate from the disadvantages of the prior art. The slides of the present
invention use
Nylon T"" or similar self-lubricating polymer materials secured onto metal or
plastic slides
in place of ball bearings and as a means to reduce friction and facilitate the
relative
extension and contraction of the slide members relative to one another. The
metal or
plastic slides can themselves slide against a polymer clad raceway. The slide
assembly
can contain a conventional fixed and one moveable slide, or one fixed slide
and a
plurality of extendable slide members. Some of the advantages of polymer based
slides
include improved performance with respect to the reduction of "lateral
wobble". This
arises as a result of the use of lubricious polymers such as Nylon T"" or
HytreIT"~
(polymer)/steel mating profile. The present slide does not require tolerances
as tight as
caged ball bearing slides.
If metal slide members are used, they can be ferrous or non-ferrous depending
upon
application requirements. Moreover, the slide members can be relatively simple
in
cross-sectional profile and can therefore be roll formed instead of stamped,
which
reduces manufacturing costs.
It is felt as well that the use of polymer based slides improves the feel of
the product with
respect to "pull-out" and provides a quieter ride.
In a preferred embodiment, the lubricious polymer can run along the entire
length of the
slide member, not just one-third of its length as with ball bearing slides,
and this further
reduces vibration as the moveable slide member moves along the fixed slide
member.
The present slides should also require less space and have less width so that
the slide
components can be better hidden or will at least take up less space in a
furniture
assembly. As well, dust and dirt should not affect polymer based slides as
much as ball
bearing slides. Nor is precise alignment of the components as critical,
because the
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lubricious polymer runs along the entire length of the slide members. As well,
simplicity
and manufacturing is further enhanced by virtue of the reduced number of
components
and reduced tolerances in the finished assembly.
Brief Description of the Drawings
Preferred embodiments of the present invention will now be described in
greater detail
and will be better understood when read in conjunction with the following
drawings in
which:
Figure 1 is an end elevational view of a double track polymer based drawer
slide;
Figure 2 is an end elevational view of a triple track polymer based drawer
slide;
Figure 3 is an end elevational view of a double track slide having dual
durometer
polymer bearings;
Figure 4 is an end elevational view of a modified triple track polymer based
slide;
Figure 5 is an end elevational view of a modified double track polymer based
slide;
Figure 6 is a perspective truncated view of the double truck slide of Figure
5;
Figure 7 is a perspective view of a further modified triple track polymer
based slide;
Figure 8 is a perspective view of an outer slide member including a polymer
raceway;
Figure 9 is a perspective view of an inner slide member for use with the outer
slide
member shown in Figure 8;
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Figure 10 is a perspective view of slide members having segmented or
incremented
polymer raceways;
Figure 11 is a perspective view of slide members having modified segmented or
incremental raceways;
Figure 12 is an end elevational view of the slide of Figure 11; and
Figure 13 shows schematical representations of different geometric
configurations for
polymer based slides.
Detailed Descriation
With reference to Figure 1, there is shown a basic double track drawer slide 1
in
accordance with one aspect of the present invention. The slides can find use
in a
number of different applications but for purposes of the following
description, the most
conventional use of slidably mounting a drawer to a furniture frame will be
referred to.
Slide 1 comprises a first outer slide 5 that will normally be fastened to the
framework by
screws, glue or any other suitable means known in the art. The upper and lower
edges
6 and 7 of slide 5 are rolled over as shown in the figure to define
longitudinally extending
raceways 8 and 9 which define a glide surface for longitudinally extending
beads of
lubricious polymer 15 applied to inner slide 25 which is the slide that will
normally be
fastened to the drawer. The dimensions of the inner slide are chosen so that
with beads
15 applied, it fits closely within the outer slide with beads 15 gliding
against raceways 8
and 9 for a close but "low effort" fit. As will be known to those skilled in
the art, the
beads of polymer can be adhered to inner slide 25 using an extrusion process
after first
coating the inner slide with a tie layer that will allow the beads to bond
covalently with the
slide which itself may be manufactured from ferrous or non-ferrous metal. The
slides
can also be manufactured from other materials such as vinyl, plastic or
fibreglass. If the
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slides are manufactured from aluminum, they can be extruded and the polymer
beads
can be co-extruded therewith.
In the remaining figures, like numerals have been used to identify like
elements.
In Figure 2, a triple track slide is shown which allows for greater extension
of the
drawer's pullout. This slide uses the same outer slide 5, a concentrically
disposed
intermediate or middle slide 10 and an inner slide 26 having the profile shown
in this
view. Outer slide 5 includes raceways 8 and 9 for lubricious polymer beads 15
on middle
slide 10. Middle slide 10 includes its own raceways 8 and 9 for a
cooperatively sized
bead of lubricious polymer 16 applied to the upper and lower edges 27 and 28
of inner
slide 26. Rather than beads of polymer, layers or coatings can be applied to
the middle
and inner slides.
The drawer slide of Figure 3 is substantially the same as the slide shown in
Figure 1
except that polymer beads 15 are a "dual durometer" co-extrusion of an outer
layer 13
of lubricious polymer such as NylonT"", HytreITM or TefIonT"" and an inner
core 14 of
relatively soft or lower durometer polymer. This construction is expected to
reduce
vibration as the drawer is pulled out or pushed in, and by allowing the outer
layer 13 to
deform by compression of the softer core, the possibility of "binding" is
reduced and
small errors in alignment or in finished tolerances can be compensated for.
With reference to Figure 4, there is shown a modification to the triple track
slide of Figure
2. In this embodiment, the rolled over upper and lower edges of middle slide
10 are
occupied by a longitudinally extending lubricious polymer raceway 30 which
provides the
glide surface for a rounded bead 18 of soft polymer or metal applied or formed
to the
upper and lower edges of inner slide 26. As shown in Figures 5 and 6, the
middle and
inner slides 10 and 26 can be adapted for use together as a double track
drawer slide.
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Figures 7, 8 and 9 show a triple track raceway in which the middle and inner
slides are
based on the same constructions as described above but the polymer beads 15 on
middle slide 10 are received into and glide against a lubricious polymer
raceway 22
inserted into the rolled over portions 8 and 9 of outer slide 5.
In some instances, it may be desirable that the polymer raceways be allowed to
flex or
articulate somewhat. This can be particularly desirable in the transitional
movement
between the drawer at rest and the drawer being either pulled out or pushed
in. To
permit this, the raceways can be either segmented, as shown in Figure 10, or
incremented with a series of spaced apart cuts 36 as shown most clearly in
Figure 11.
It is contemplated that the segmented raceways can be allowed to float or
"walk" with the
inner slide as its moved back and forth.
In this embodiment, the upper and lower edges of outer slide 35 are bent over
at a 90°
angle as seen most clearly in Figure 12. A raceway 40 is applied to the inside
of the
bends and may be a dual durometer construction consisting of a first outer
layer 42 of
relatively soft, flexible polymer such as SantopreneT"~, KratonT"" based
rubber, styrenic
co-polymer with KratonT"" based rubbers as a compound from GLS, or
polyurethane and
an inner layer 41 of lubricious polymer formed with a longitudinally extending
rounded
groove 49 which is the glide surface for cooperatively shaped polymer or metal
bead 48
applied to the upper and lower edges of inner slide 26. At least the outer
side surface
or skirt 44 of outer layer 42, and perhaps the inner skirt 45 as well, is
formed with a
series of spaced apart nicks or cutouts 36 that allows or at least facilitates
the flexing or
articulation of raceway 41 along the longitudinal axis of drawer movement when
transitioning from the static to a dynamic state. To further reduce friction,
beads 48 can
be metal rather than polymer, and whether the beads are metal or polymer, a
lubricant
can be added between the beads and groove 49.
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Outer layer 42 can be formed in discrete segments or can be full length
relative to bead
48. If the outer layer is segmented, the segments can be allowed to float or
walk freely
back and forth as the drawer is opened and closed.
As will be appreciated, a lubricant can be used in any of the above described
embodiments, and the materials for the beads and the raceways can be selected
to
provide either a polymer to polymer, polymer to metal or even metal to metal
glides. The
lubricious polymers can be infused or compounded with oils, greases,
lubricious fluids
or additives such as molybodenum disulfide to further reduce their coefficient
of friction
Figure 13 includes a schematical representation of alternative drawer slides
utilizing the
principles of construction and operation described above.
The above-described embodiments of the present invention are meant to be
illustrative
of preferred embodiments and are not intended to limit the scope of the
present
invention. Various modifications, which would be readily apparent to one
skilled in the
art, are intended to be within the scope of the present invention. The only
limitations to
the scope of the present invention are set forth in the following claims
appended hereto.
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