CA2437147A1 - Drawer slide - Google Patents

Abstract

There is described a drawer slide comprising at least first and second slide members, one of said members being moveable relative to the other, and lubricious polymer being disposed between the slide members to facilitate low friction sliding movement of one slide member relative to the other.

Description

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.

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

-2-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;

-3-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

-4-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.

-5-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.

-6-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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Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A drawer slide comprising at least first and second slide members, one of the members being moveable relative to the other, and lubricious polymer disposed between said slide members to facilitate said relative movement therebetween.

2. The drawer slide of claim 1 wherein said lubricious polymer is applied to one of said first or second slide members and is disposed thereon to slidably engage the other of said first or second slide members.

3. The slide member of claim 2 wherein at least a portion of said second slide member is disposed for movement within said first slide member, and said lubricious polymer is applied to said second slide member on surfaces thereof in opposition to adjacent surfaces of said first slide member for low friction gliding movement of said second slide member in a back and forth movement relative to said first slide member.