GB2375287A

GB2375287A - Drawer Strengthening Member

Info

Publication number: GB2375287A
Application number: GB0202807A
Authority: GB
Inventors: Michael Richard Head
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-07
Filing date: 2002-02-07
Publication date: 2002-11-13
Anticipated expiration: 2022-02-07
Also published as: GB2375287B; GB0202807D0

Abstract

The invention relates to a shaped strengthening member, 1, for the reinforcing of furniture and a method of using it. The strengthening member, 1, for reinforcing the base panel of a drawer, comprises an elongate strip of material having two end portions, 3 and 6, with means at both ends for attaching the member to walls of the drawer, 2 and fig 3 (8),. The centre portion, 9, between said ends has increasing rigidity so as, in use, to support said the base panel. The member may be secured to the front and back walls of the drawer using screws through the apertures, this supports the drawer base panel. It is preferably formed from a pressed light gauge steel strip with a longitudinal reinforcing rib,4, one end bent perpendicular to the main part of the member,6, and the other end optionally bendable to fit varying drawer depths, fig 5 (22). An end of the member is also capable of being detached to conveniently vary it's length, fig 6 (32).

Description

STRENGTHENING MEMBER FOR REINFORCING FURNITURE This invention relates to strengthening members for the reinforcing of furniture and a method of using such strengthening members. In particular the invention relates to strengthening members for reinforcing a base of a conventional furniture drawer.

The almost universal use of drawers, sliding open topped boxes, in chests, tables, bureaux and other furniture items, has been established as a means of providing access to objects stored within the furniture items for centuries. In previous times drawers were constructed from rectangular sheets of wood joined by carpentry joints or fasteners. For heavy duty industrial use steel or other metal sheet has substituted for wood, but such structures suffer from weight and aesthetic disadvantages for domestic service.

In latter years, the use of alternative sheet materials such as chipboard, hardboard, plastic and composite structures such as extrusions or plastic coated pressed board has become popular for reasons of weight reduction, cost reduction, friction reduction and ease of cleaning among others.

In particular, the base of a drawer is often made from a product such as hardboard, a sheet material made by subjecting fibers made from wood or other chippings to combinations of heat and pressure. The base may not be attached to the sides, back and front of the drawer, merely resting in slots recessed into the sides of the other components, which form a frame for the base when they are assembled. (Normally, the drawer front also incorporates a handle or knob set into its side for opening and closing the drawer. This mechanism does not interfere with the base). The use of such recessed slots in domestic furniture for retaining the base lends itself to quick assembly of the drawer from its constituent components.

However, a disadvantage is that such materials as hardboard are inherently flexible, deflecting readily under a light loading to large permanent and/or elastic out-of-plane deformations under the influence of bending stresses. With a heavy loading of objects into the drawer for storage, or with too great a span of the bottom sheet, said bottom sheet may pull out of the recesses provided by back, front or sides, leading to collapse of the bottom by bowing. Distortion outwards of the back panel of the drawer due to pressure from the deflecting base, ('bellingout'), may also occur. It may be difficult or impossible to replace the bottom sheet in the recesses, or the bottom may have been damaged by the collapse, and the security of the stored objects will have been endangered.

This problem of collapsing drawers is widespread. With a housing stock of 20 million properties in the U. K. alone, there is evident a real need for a simple effective solution for a minimum of 30 million drawers.

To date, there is no simple solution for the general public, other than to attempt an'ad hoc'fix or to scrap the offending furniture and purchase anew, frequently a complete suite of furniture at considerable cost. The problem is not limited to cheap furniture; even expensive modern furniture exhibits the problem. Research has revealed no available commercial solution.

There is the therefore a need for means to prevent the failure mechanisms outlined above, by providing a cost-effective simple means to support the base, providing means to resist out-of-plane bending of the base sheet, while constraining the separation of opposing pair elements of the drawer, for example front and back, or alternatively the two sides.

According to a first aspect of the invention there is provided a strengthening member for reinforcing a base panel of a drawer, the strengthening member comprising an elongate strip of material having two end portions and a centre portion between said ends wherein the strengthening member is provided with

means at both ends for attaching the member to walls of the drawer and means for increasing ngidity of the centre portion so as, in use, to support said base panel.

The invention may be used for retro-fitting to drawers of existing bureaux, chests, tables, etc. , as well as for incorporation into new furniture products.

It is a further purpose of the invention to provide said strengthening member which, when fitted, is unobtrusive, visible only from the underside and rear (or side) of the drawer, not obvious from other orientations, and does not detract from the aesthetic appeal of furniture items, being invisible from the outside of the supporting cabinet. Such a strengthening member may be made from a multiplicity of materials, including metal, plastic or composite formulations.

In a preferred embodiment of the invention, the strengthening member may be formed from a deformable metal strip of thickness sufficiently small to permit the forming of one or a plurality of raised reinforcing spines or ribs along the long axis, by a process of deformation such as roll-forming or sheet metal pressing.

The edges of the strengthening member along the strengthening member axis may remain planar. Areas at both ends of the strengthening member may also remain planar during the above deformations, these ends may provide fastening lugs. One end may be bent through a right angle about an axis in the sheet plane transverse to the strengthening member long axis, such that it extends normal (perpendicular) to a principal plane of the strengthening member in the same or opposite direction to the raised spines or rib. This end may provide a fastening lug for attachment to the drawer front, for example, under the drawer base (attachment to the drawer in side-to-side orientation is also an option). The lug may afford means of fixing to the drawer front, by, for example, drilled or punched holes for attachment with screws, nails, pins, or may be thin enough for use of staples. Such holes may be formed by a roll-forming or sheet metal pressing process. Alternatively the strengthening member may be formed from

material sufficiently thin and malleable that a fastener, such as a brad or staple, may be made to pierce the member and secure the member to a drawer.

Strengthening members of the invention may be formed of metal strip of between 0.2 and 1.0 mm thickness. In original equipment drawers the strengthening member could also, for example, be welded or glued in place. The remote end of the strengthening member may be planar with provision for fixing means, but asmanufactured may not be bent through a right angle (perpendicular to the principal plane of the strengthening member). This permits flexibility in drawer-todrawer variation of, for example, depth or width of a drawer by means of a subsequent wrapping (bending to a surface of a wall of a drawer) operation as described below.

An example of the preferred embodiment of the invention comprises a prestressed (by deformation), formed galvanized mild steel strengthening member, extremely easy to fit and of very low cost. The strengthening member may be wholly or partially coated, for example, by painting. Once fitted it is invisible and will not impair the appearance or performance of the drawer. On the contrary, strengthening members may improve the load carrying capacity of the drawer base by as much as three times the original manufactured drawer. The depth of drawers from front fascia to rear panel (i. e. front to rear drawer walls) varies amongst manufacturers, but not greatly, so drawer depth usually falls within a range of 12 to 16 inches. The construction of a strengthening member of the present invention is such that it can be manipulated to suit a variation in this depth of drawer from front fascia to rear panel. The unique form of the strap also takes account of the'front to back'tensional strength required, preventing'belling out'and, importantly, increasing the bending strength of the hardboard base. Increased strength may be obtained by use of more than one strengthening member.

According to a second aspect of the invention there is provided a method of reinforcing a drawer base comprising attaching a strengthening member, as previously described to any two walls of a drawer.

In an embodiment of a method according to the invention for installation under the drawer is as follows. The right-angled bent lug is attached to the drawer front at the back of the drawer front wall, snugly supporting the drawer base underneath, through the plane edges of the profiled strengthening member, with the strengthening member axis substantially normal to the plane of the drawer front. Once attached to the front, the strengthening member is pushed up into close contact with the drawer base, and the plane end lug is wrapped, by bending, tightly up and around the rear face of the drawer back. It may then be attached to the drawer back by such alternative means as previously described.

The spine or rib feature of the strengthening member along its long axis allows much greater stiffening of a drawer base than would a simple planar strengthening member of equal thickness and width.

According to a third aspect of the invention there is provided a drawer comprising a base panel supported by a strengthening member, as previously described, which is attached to two walls of the drawer.

It is preferred that strengthening members of the invention as attached to a drawer are under a, low, tensile stress between the front and rear walls of the drawer. The base is therefore less liable to be disengaged from any retaining slot. It is also preferred that the strengthening member serves to directly support a base of the drawer. In particular any tensile stress thereby simultaneously improves support for the base panel. In particular if the base of the drawer bows outward the pre-tensioned strengthening member is less liable to deflect.

In applying a strengthening member to a drawer, particularly during a process of drawer repair, it is preferable to place an inward force on walls to be connected

by the strengthening member. This may be achieved by means such as a sash clamp. However, particularly for consumer use, a method of exerting a force by means of a tourniquet is preferred. In such methods, the inward force is applied to the walls to which the strengthening member is to be attached, the strengthening member is attached and the means for applying the force removed. The strengthening member may thereby be left in a state of tensile stress.

Examples of the invention will now be described by way of illustration only with reference to the accompanying drawings, in which like elements are designated by like numerals and in which : Figure 1 shows a strengthening member of a first embodiment of the invention in plan view ; Figure 2 shows a strengthening member of the first embodiment of the invention in side elevation ; Figure 3 shows a strengthening member of the first embodiment of the invention in an end elevation ; Figure 4 shows a cross section through a strengthening member of the first embodiment the invention in piane ll-ll of figure 2; Figure 5 shows a side elevation of a second embodiment of the invention; Figure 6 shows a plan view of a third embodiment of the invention; Figure 7 shows a side elevation of a method of attaching the second embodiment of the invention;

Figure 8 shows a perspective view illustrating a method of attaching the second embodiment of the invention; Figure 9 shows a perspective view of the second embodiment of the invention attached to a drawer; Figure 10 shows a side elevation of a fourth embodiment of the invention attached to a drawer; Figure 11 shows a side elevation of a fifth embodiment of the invention attached to a drawer; Figure 12 shows a perspective view of a sixth embodiment of the invention; Figure 13 shows a perspective view of a seventh embodiment of the invention and Figure 14 which shows the attachment of an eighth embodiment of the invention to a drawer.

Figures 1 to 4 show a first embodiment of the invention. An elongate steel strengthening member is shown at 1 and comprises apertures 2 in a planar end portion 3. A single rib 4 forms a rigid centre portion 9 that extends down the middle of the strengthening member and tapers at both ends to planar portions 3,5. Planar end portions 3,5 define a principal plane of the strengthening member in conjunction with principal axis !-). An end plate 6 of the strengthening member is perpendicular to the principle plane of the strengthening member and comprises two apertures 8. The end plate 6 is opposite, in terms of the principal plane, to the rib 4. A cross section of the strengthening member 1 through ( -))) shows a form of the rib 4 which imparts sufficiently rigid character to the centre portion of the strengthening member 9. The ends of the rib 4 taper at an angle of

about 15 degrees to the principal plane. All corners of the strengthening member are rounded 10.

In use the strengthening member 1 is placed on the underside of a drawer Screws through apertures 8 in the end plate 6 secure the strengthening member to an inside lower edge of a front wall of the drawer. The main portion of the strengthening member spans a base panel of the drawer and further screws through apertures 2 secure the other end of the strengthening member to a lower edge of a rear wall of the drawer.

Figure 5 shows a second embodiment 20 of the invention wherein the end plate 6 lies on the same side of the principal plane as the reinforcing rib 4.

More than one set of apertures may be present in the elongate planar portion 22.

Figure 6 shows a third embodiment of the invention. Elongate mild steel strengthening member 30, arranged otherwise substantially as the second embodiment, comprises a shorter planar end portion 3 with associated apertures 2 arranged pair wise. At one end of the strengthening member, and integral with it, is a detachable portion 32 with associated apertures 38 arranged pair wise.

Between the planar end portion 3 and the detachable portion 32, which is also planar, is a modified region.

In one variation on the third embodiment of the invention the modified region comprises notches 36 in opposing edges of the strengthening member. In another variation on the third embodiment of the invention the modified region comprises a line of mild steel of reduced thickness 34. In a further variation on the third embodiment of the invention the modified region comprises both notches 36 and the line of reduced thickness 34.

In use the strengthening member 30 is placed on the underside of a drawer. The strengthening member 30 is secured by end plate 6 to an inside base edge of a front wall of a drawer. The strengthening member may be further secured to a rear wall by means of screws through apertures 38 in the tab portion 32. Should

the shorter end portion overlap the rear wall, the detachable portion 32 is superfluous. The detachable portion 32 may then removed by repeatedly bending about notches 36 and/or line 34.

In use strengthening members according to the second and third embodiments of the invention may be attached in the following manner, as illustrated in Figure 7.

Screws 72 through apertures 8 in the end plate 6 secure the strengthening member 70 to an inner lower face of a front wall 56 of a drawer 54 using screws 72. A central portion of the strengthening member spans a base panel 60 of the drawer, so as to contact and support the base panel 60. An elongate planar end portion 22 of the strengthening member overlaps a rear wall 58. An overlapping strengthening member portion 74, pivoting on a pivot edge 76, is bent to a position 78 (indicated by a dashed line) perpendicular to a start position and secured using further screws 73 through apertures in the strengthening member (not shown).

Figure 8 shows a tourniquet 80 being tightened using a torsion bar 82 so as to apply a compressive force between the front and rear 58 walls. Overlapping strengthening member portion 74 is bent over the edge 76 to a position 78 (indicated by dashed lines) perpendicular to a start position and secured by means of screws 84. The tourniquet may then be removed and the strengthening member 70 is left in tension. An end result is shown in Figure 9. The strengthening member 70 when in tension simultaneously holds the front 56 and rear 58 walls of a drawer 90 and also supports the base panel 60. The base is therefore less liable to be disengaged from any retaining slot. In addition if the base of the drawer 60 bows outward the pre-tensioned strengthening member 70 is less liable to deflect.

Further embodiments of the invention are shown in figures 10 to 14.

Figure 10 shows a fourth embodiment of the invention configured similarly to the second embodiment of the invention. However, a planar end portion 3 is modified by a bend 102 so as to allow a partially recessed base panel 60 to be contacted

and supported by the central portion of the strengthening member 100 throughout a substantial portion of the length of the strengthening member.

Figure 11 shows a fifth embodiment of the invention configured to allow the rib 4 to directly support a recessed base panel 60.

Figure 12 shows a substantially planar strengthening member 120 with a reinforcing rib 4. Such a strengthening member is particularly suitable for attaching across a drawer between the lower edges of side panels particularly when any runners for the drawer are along walls of the drawer Thus the member 120 is oriented transverse to the sliding direction of the drawer.

Figure 13 shows an embodiment 130 similar to the second embodiment of the invention but with the end plate 132 at an acute angle (yet substantially perpendicular) to a principal plane of the strengthening member. First attachment of this strengthening member 132 to a lower inner edge of a front wall of a drawer is facilitated where a drawer base panel is deformed (bowed outward) as the strengthening member is angled away from the base panel on first attachment. In addition, subsequent flattening of the strengthening member so as to attach the strengthening member to a rear wall may perform a useful leverage function to press the deformed (bowed outward) base panel of a drawer back in place.

Figure 14 shows a further embodiment 140 being a pre-formed strengthening member similar to the second embodiment as subsequent to application using the aforementioned method. Such a strengthening member 140 is particularly suitable for application as a reinforcing member to a new drawer as originally manufactured since staples may be applied to secure the strengthening member without altering the orientation of a staple applicator relative to the drawer.

The term'lower parts'of components refer to the orientation of those components in normal operation.

Example Extended trials have been conducted on drawers of the following dimensions :- Drawer width = 760mm.

Drawer front to back depth = 355mm.

Hardboard base thickness = 4mm.

Side panel thickness = 10.3mm.

A strengthening member of the first embodiment of the invention was attached to a drawer in the manner described above and as illustrated in Figures 7 resulting in a configuration akin to that shown in Figure 9 and described above.

Loading of conventional drawers to support a weight of 18kg caused a gradual distortion of the base over a period of three months,'belling out'of the rear panel, and ultimately total collapse. By extreme contrast, loading of drawers, each supported with a drawer reinforcing strengthening member according to the present invention, permitted a loading of the drawers of 45kg with minimal distortion and no catastrophic failure over a period of three years.

Claims

Claims 1. A strengthening member for reinforcing a base panel of a drawer, the strengthening member comprising an elongate strip of material having two end portions and a centre portion between said ends wherein the strengthening member is provided with means at both ends for attaching the member to walls of the drawer and means for increasing rigidity of the centre portion so as, in use, to support said base panel.
2. A strengthening member as described in claim 1 wherein the means at both ends for attaching comprises apertures in the strengthening member for receiving fastening means.
3. A strengthening member as described in either of claims 1 or 2 wherein the means for increasing rigidity of the centre portion comprises a non-planar portion of the strengthening member.
4. A strengthening member as described in claim 3 wherein the non-planar portion of the strengthening member is a channel shaped depression along a longitudinal axis of the strengthening member.
5. A strengthening member as described in claim 4 wherein the channel shaped I L I'll depression along a longitudinal axis of the strengthening member has a generally U shaped cross-section.
6. A strengthening member as described in any previous claim wherein a first end is perpendicular to a principal plane of the strengthening member.
7. A strengthening member as described in claim 6 wherein an end remote to the first end of the strengthening member is perpendicular to the principal plane of

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the strengthening member and is on an opposite side of the strengthening member to that of the first end.
8. A strengthening member according to any previous claim wherein a region near an end of the strengthening member comprises a modified portion across the strengthening member so as to facilitate detachment of an end portion of the strengthening member adjacent to the modified portion.
9. A strengthening member according to any previous claim wherein the strengthening member comprises a material selected from the group comprising: a metal ; a plastic ; and a composite material.
10. A strengthening member according to claim 9 wherein the strengthening member comprises mild steel.
11. A strengthening member according to any previous claim wherein the material of the strengthening member is from 0.2 to 1. Omm thick.
12. A drawer having a base panel and including a strengthening member, as described in any previous claim, wherein the strengthening member is attached to two walls of the drawer.
13. A drawer as described In claim 12 wherein the two walls are a front wall and a back wall of the drawer.
14. A drawer as described in either of claims 12 or 13 wherein more than one strengthening member is attached to the drawer.
15. A method of reinforcing a drawer base comprising attaching a strengthening member, as described in any one of claims 1 to 11, to any two walls of a drawer.

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16. A method as described in claim 15 wherein the walls selected are parallel to one another.
17. A method as described in claim 16 wherein the strengthening member is attached to an inner face of a front wall of a drawer and a rear face of a rear wall of the drawer.
18. A method as described in any one of claims 15 to 17 wherein more than one strengthening member IS attached.
19. A kit of parts comprising a strengthening member as described in any one of claims 1 to 11 and two or more fasteners suitable for attaching the strengthening member to walls of a drawer.
20. A kit of parts as described in claim 19 wherein the fasteners are screws.
21. A strengthening member as hereinbefore described with reference to the accompanying description and Figures 1 to 4; or Figure 5; or Figure 6; or Figure 10; or Figure 11; or Figure 12; or Figure 13; or Figure 14 of the drawings.

21. A strengthening member as hereinbefore described with reference to the accompanying description and Figures 1 to 4; or Figure 5; or Figure 6; or Figure 10; or Figure 11; or Figure 12; or Figure 13 ; or Figure 14 of the drawings.

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AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS Claims

1. A strengthening member for reinforcing a base panel of a drawer, the strengthening member consisting of an elongate strip of material having two end portions and a centre portion between said ends wherein the strengthening member is provided with means at both ends for attaching the member to walls of the drawer and means for increasing rigidity of the centre portion so as to support said base panel in use.

2. A strengthening member as described in claim 1 wherein the means at both ends for attaching comprises apertures in the strengthening member for receiving fastening means.

3. A strengthening member as described in either of claims 1 or 2 wherein the means for increasing rigidity of the centre portion comprises a non-planar portion of the strengthening member.

4. A strengthening member as described in claim 3 wherein the non-planar portion of the strengthening member is a channel shaped depression along a longitudinal axis of the strengthening member.

5. A strengthening member as described in claim 4 wherein the channel shaped depression along a longitudinal axis of the strengthening member has a generally U shaped cross-section.

6. A strengthening member as described in any previous claim wherein a first end is perpendicular to a principal plane of the strengthening member.

7. A strengthening member as described in claim 6 wherein an end remote to the first end of the strengthening member is perpendicular to the principal plane of

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the strengthening member and is on an opposite side of the strengthening member to that of the first end.

8. A strengthening member according to any previous claim wherein a region near an end of the strengthening member comprises a modified portion across the strengthening member so as to facilitate detachment of an end portion of the

strengthening member adjacent to the modified portion. l

9. A strengthening member according to any previous claim wherein the strengthening member comprises a material selected from the group comprising: a metal ; a plastic ; and a composite material.

10. A strengthening member according to claim 9 wherein the strengthening member comprises mild steel.

11. A strengthening member according to any previous claim wherein the material of the strengthening member is from 0.2 to 1. Omm thick.

12. A drawer having a base panel and including a strengthening member, as described in any previous claim, wherein the strengthening member is attached to two walls of the drawer.

13. A drawer as described in claim 12 wherein the two walls are a front wall and a back wall of the drawer.

14. A drawer as described in either of claims 12 or 13 wherein more than one strengthening member is attached to the drawer.

15. A method of reinforcing a drawer base comprising attaching a strengthening member, as described in any one of claims 1 to 11, to any two walls of a drawer.

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16. A method as described in claim 15 wherein the walls selected are parallel to one another.

17. A method as described In claim 16 wherein the strengthening member is attached to an inner face of a front wall of a drawer and a rear face of a rear wall of the drawer.

18. A method as described in any one of claims 15 to 17 wherein more than one strengthening member is attached.

19. A kit of parts comprising a strengthening member as described in any one of claims 1 to 11 and two or more fasteners suitable for attaching the strengthening member to walls of a drawer.

20. A kit of parts as described in claim 19 wherein the fasteners are screws.