US20020102034A1

US20020102034A1 - Apparatus with form-in-place bearing

Info

Publication number: US20020102034A1
Application number: US09/774,502
Authority: US
Inventors: Russell Holdredge
Original assignee: Steelcase Development Inc
Current assignee: Steelcase Development Inc
Priority date: 2001-01-31
Filing date: 2001-01-31
Publication date: 2002-08-01

Abstract

A furniture article, such as a telescopingly adjustable column for chair height adjustment or an adjustable table leg, includes a tubular first member and a tubular second member telescopingly and rotatably supported by the first member. A sleeve-like bearing is positioned between the first and second members. The bearing has an original pre-cured shape that fits loosely into the clearance space between the members during assembly, and further has lubricious bearing material to facilitate smooth extension of the members, but further is made at least in part of a material that when cured expands to a size and shape that takes up an increased percentage of the clearance space. By this arrangement, the bearing can be easily positioned in the clearance space, but after thermal curing the bearing expands to reduce wobbling and looseness between the first and second members.

Description

BACKGROUND

The present invention relates to bearings such as may be used in furniture to support a first member for rotation within or extension from a second member. For example, the present inventive bearing can be used to support telescoping members in a chair support column. Nonetheless, it is to be understood that the present concepts are not believed to be limited to furniture, nor to only telescoping movement.

Bearing arrangements are often desired in furniture to operably support members for smooth rotation and/or extension and retraction. For example, it is desirable to provide adjustable chair control “columns” that are smoothly and easily rotatable and adjustable for selective chair height adjustment, and table legs that are smoothly and easily adjustable for worksurface height adjustment. Further, the bearing arrangements need to have close tolerance fit to eliminate wobbling and undesirable looseness, yet without unacceptable dragging. This is can achieved by secondary operations such as machining or reaming, or by adjustment mechanisms that allow a close fit to be made without wedging despite manufacturing variations. However, secondary operations are expensive and require manufacturing manpower and time. Further, they can require expensive machinery to perform the operation. Adjustment mechanisms typically involve multiple parts, pieces, and/or tools, and also require manufacturing manpower and time.

Accordingly, an apparatus is desired solving the aforementioned problems and having the aforementioned advantages.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a furniture article includes a first member and a second member configured to operably support the first member, the first and second members having opposing surfaces defining a clearance space therebetween. The furniture article further includes a bearing located between the opposing surfaces. The bearing has an original pre-cured shape that fits loosely into the clearance space during assembly, but further is made at least in part of a curable material that when cured expands to a size and shape that takes up an increased percentage of the clearance space. By this arrangement, the bearing, when uncured, can be easily positioned in the clearance space, but so that after curing the bearing expands to reduce wobbling and looseness between the first and second members.

In another aspect of the present invention, a bearing arrangement is provided for movably supporting a first member in a second member, where the first and second members have opposing surfaces defining a clearance space therebetween. The bearing arrangement includes a geometrically-shaped bearing adapted to be located between the opposing cylindrical surfaces. The bearing has an original shape adapted to fit loosely into the clearance space, and further includes bearing material adapted to slidably engage one of the first and second members. The bearing still further includes a backer for supporting the bearing material that is made at least in part of a curable material that when cured expands to a size and shape adapted to take up an increased percentage of the clearance space. By this arrangement, the bearing can be easily positioned in the clearance space but after curing expands to reduce wobbling and looseness between the first and second members.

In yet another aspect of the present invention, a method of manufacturing a furniture article comprises steps of providing a first member and a second member movably supported by the first member, the first and second members having opposing surfaces defining a clearance space therebetween, and also providing a bearing having an original precured shape that fits loosely into the clearance space curing assembly, but further being made at least in part of a material that when cured expands to a size and shape that takes up an increased percentage of the clearance space. The method includes positioning the bearing in the clearance space, and curing the bearing to thus expand the bearing to reduce wobbling and looseness between the first and second members.

These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross sectional view of a chair including a telescoping and rotatable chair column with a bearing arrangement embodying the present invention; [0008]
FIG. 2 is an enlarged perspective view of the form-in-place bearing shown in FIG. 1; [0009]
FIG. 3 is a side cross sectional view of an armrest including a modified bearing arrangement; [0010]
FIG. 4 is a cross section taken along lines IV-IV in FIG. 3; and [0011]
FIGS. [0012] 5-6 are transverse cross sectional views of additional modified bearing arrangements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The illustrated chair [0013] 10 (FIG. 1) includes first and second tubular members 11 and 12 that together with an internal pneumatic gas spring form a telescopingly-adjustable column for chair height adjustment. As illustrated, the member 11 is commonly called a “hub tube”, and the member 12 is called a chair control “column”. A sleeve-like bearing 13 is positioned in a clearance space 14 between the first and second members 11 and 12. The present inventive bearing 13 has an original pre-cured shape that fits loosely into the clearance space 14 between the members 11 and 12 during assembly, but it is constructed to expand and provide a close fit when heated and cured. By this arrangement, the bearing 14 can be easily positioned in the clearance space, but after thermal curing the bearing 14 expands create a “perfect fit” that reduces wobbling and looseness between the first and second members but that provides an optimal clearance for sliding movement.
The illustrated bearing [0014] 13 (FIG. 2) has a cylindrically shaped backer 15 and has strips of lubricious bearing material 16 arranged and supported circumferentially around an inside of the backer 15. The strips of lubricious bearing material 16 are arranged to slidingly engage the tubular member 12 to facilitate smooth extension of the members 11 and 12. The backer 15 is made of a material that when cured expands to a size and shape that takes up an increased percentage of the clearance space. For example, the illustrated backer 15 is made of Terocore (a structural epoxy foam manufactured by Henkel Company) which expands some percentage when thermally cured, such as about 25% (or more or less, depending upon the material and shape). Further, the cured backer 15 shrinks a small amount when cooled, (such as about 3%) such that the resulting arrangement provides an optimally close fit at room temperature that does not bind or frictionally freeze the connection. The backer 15 further has a good strength for supporting the bearing strips 16 for long term wear and use.
It is contemplated that the [0015] backer 15 can be made of a number of different materials. The illustrated material “Terocore” will adhere to the tubular member 11 to fix the location of the bearing 15 in the member 11. This also provides improved stability to the present bearing arrangement. In the illustrated assembly, the inside surface of the backer 15 is coated by a lubricious material 17 to prevent unwanted adhesion to the member 12. It is contemplated that the member 11 and/or backer 15 can include features that mechanically interlock to fix the location of the bearing 13 in the member 11 if desired. For example, a bent tab can be formed in member 11 so that the backer 15 will form around or interlock onto the tab. If a backer material is chosen that will not adhere to the member 11, then the lubricious material 17 can be eliminated since adhesion to the member 12 is not a problem. Alternatively, if the backer material and the bearing material are arranged such that the backer material cannot contact the member 12, such as if the bearing material forms a continuous sleeve around the inside surface of the backer 15, then the lubricious material 17 can be eliminated.
The segmented and spaced-apart nature of the [0016] strips 16 prevents folding of the bearing material as the backer 15 is cured and expands inwardly. However, depending on the shape, strength, and positioning of the bearing material, and depending on the relationship of the tubular members 11 and 12 (both before and after curing) and their strength, it is contemplated that spaced-apart strips may not be required. For example, it is contemplated that the bearing strips 16 can be replaced by a continuous, uninterrupted sleeve that is stiff and thick enough to not collapse or wrinkle as the backer 15 is cured, but that is resilient and flexible enough to compress without wrinkling. Alternatively, the spaced apart bearing strips 16 can be interconnected by circumferentially extending webs or strings of material that, even if flexed inwardly, are sufficiently thin so that they do not intrude inwardly past a diameter of the innermost surfaces of the bearing strips 16.
In the illustrated arrangement, eight [0017] strips 16 made of nylon, Delrin or other lubricious material are used. The illustrated strips 16 are about 0.005 inches to 0.010 inches thick and extend a vertical length of the backer 15. In its uncured state, the bearing 13 provides about 0.020 inches of clearance between the strips 16 and the inner member 12, which facilitates assembly. In their cured and cooled state, the bearing 13 provides about 0.001 inches to 0.002 inches of clearance between the strips 16 and the inner member 12. The total thickness of illustrated bearing 13 before cure is about 0.040 inches to 0.050 inches, and after cure is about 0.050 inches to 0.059 inches thickness, but, of course, the thickness can be varied to fill a designed gap.
It is contemplated that the [0018] strips 16 can be positioned on an outer surface of the bearing 13 so that they engage the outer member 11 instead of the inner member 12.
It is contemplated that the present invention can be used on any furniture article requiring telescoping and/or rotatable adjustment, such as an adjustable table leg, adjustable chair arms and armrests, chair control mechanisms, pedestal drawer slides, and adjustable worksurfaces. [0019]
It is further contemplated that the present inventive concepts can be used on any telescoping mating members where smooth extension is desired through use of a low-clearance bearing arrangement using parts that require only minimal manual assembly. This is true regardless of the cross sectional shape of the tubes. For example, FIGS. [0020] 3-4 disclose an armrest 30 having a rectangular outer fixed support tube 31, a mating inner arm tube 32 carrying an armrest 32A, and a pair of bearings 33 and 34 in the clearance space 35. The bearings 33 each include a backer made of Terocore material that expands when cured, and bearing strips, much like the bearings 13. The bearings 33 and 34 can extend continuously around the inner arm tube 32, or can include L-shaped wall sections that define corners of a rectangle (see FIG. 4). A lubricious film can be applied to increase lubricity and decrease a tendency of the Terocore material to bond to one of both of tubes 31 and 32. Strips of bearing material can extend partially or completely around the inner tube 32. FIG. 5 discloses an arrangement 40 having a non-uniform cross section, including an outer tube 41, an inner tube 42, and longitudinally-spaced tubular bearings 43. FIG. 6 discloses an arrangement 50 having a non-uniform cross section, including an outer tube 51, an inner tube 52, and three point bearings 53A, 53B, and 53C. It is contemplated that bearings 53B and 53C could be combined to form a single C-shaped bearing that captures the inner tube 52, if desired. Also, it is noted that the bearings 43 and 53 have non-uniform thicknesses and still function well. The bearings 43 and 53 include a backer of curable/expandable Terocore material, and bearing strips as needed for long term wear and lubricity. A lubricious film is applied, if needed.
It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise. [0021]

Claims

The invention in which a property right or privilege is claimed is:

1. A furniture article comprising:

a first member and a second member configured to operably support the first member, the first and second members having opposing surfaces defining a clearance space therebetween; and

a bearing located between the opposing surfaces, the bearing having an original pre-cured shape that fits loosely into the clearance space during assembly, but further being made at least in part of a curable material that when cured expands to a size and shape that takes up an increased percentage of the clearance space, so that the bearing, when uncured, can be easily positioned in the clearance space, but so that the bearing, after being cured, expands to reduce wobbling and looseness between the first and second members.

2. The furniture article defined in claim 1, wherein the curable material is made of a polymer that cures to a hardened state when heated.

3. The furniture article defined in claim 2, wherein the original pre-cured shape of the bearing expands to completely fill the clearance space when heated, but further shrinks a small amount when cooled after curing to define a reduced clearance space that reduces wobbling and looseness between the first and second members, but still permits movement therebetween.

4. The furniture article defined in claim 1, wherein the curable material adheres to one of the first and second members, but not the other.

5. The furniture article defined in claim 4, including a lubricious coating material applied to the curable material to increase the lubricious nature thereof.

6. The furniture article defined in claim 1, wherein one of the first and second members is tubular and completely surrounds the other member.

7. The furniture article defined in claim 1, wherein the curable material forming a backer that surrounds the second member, and further includes bearing strips supported by the backer.

8. The furniture article defined in claim 1, wherein the bearing includes bearing strips supported in the curable material for sliding engagement with one of the first and second members.

9. The furniture article defined in claim 1, wherein the first member is telescopingly extendable from the second member.

10. The furniture article defined in claim 9, wherein the first member is rotatably supported in the second member.

11. The furniture article defined in claim 10, wherein the first and second members form a part of a vertically extendable chair column.

12. The furniture article defined in claim 9, wherein the first and second members form a telescopingly extendable table leg.

13. The furniture article defined in claim 9, wherein the first and second members define a drawer glide.

14. A bearing arrangement for movably supporting a first member in a second member, where the first and second members have opposing surfaces defining a clearance space therebetween, the bearing arrangement comprising:

a geometrically-shaped bearing adapted to be located between the opposing cylindrical surfaces, the bearing having an original shape that fits loosely into the clearance space, the bearing including bearing material adapted to slidably engage one of the first and second members and including a backer for supporting the bearing material, the backer being made at least in part of a curable material that when cured expands to a size and shape adapted to take up an increased percentage of the clearance space, so that the bearing can be easily positioned in the clearance space but after curing expands to reduce wobbling and looseness between the first and second members.

15. The bearing arrangement defined in claim 14, wherein the geometrically shaped bearing defines a tube section.

16. The bearing arrangement defined in claim 14, wherein the curable material of the backer is polymeric and curable by heat.

17. The bearing arrangement defined in claim 14, wherein the backer adheres to one of the first and second members when heated.

18. A method of manufacturing a furniture article comprising steps of:

providing a first member and a second member telescopingly supported by the first member, the first and second members having opposing surfaces defining a clearance space therebetween;

providing a bearing having an original pre-cured shape that fits loosely into the clearance space curing assembly, but further being made at least in part of a material that when cured expands to a size and shape that takes up an increased percentage of the clearance space;

positioning the bearing in the clearance space; and

curing the bearing to thus expand the bearing to reduce wobbling and looseness between the first and second members.

19. The method defined in claim 18, wherein the step of curing includes heating the bearing.

20. The method defined in claim 19, wherein the material that expands when cured comprises a polymeric material.

21. The method defined in claim 18 including a step of applying lubricious coating to only one side of the bearing.