AU731639B2

AU731639B2 - Improvements in/or relating to methods of strengthening desk tops and/or apparatus used therefor

Info

Publication number: AU731639B2
Application number: AU37497/97A
Authority: AU
Inventors: Robert Bruce Stewart
Original assignee: Formway Furniture Ltd
Current assignee: Formway Furniture Ltd
Priority date: 1996-09-11
Filing date: 1997-09-11
Publication date: 2001-04-05
Anticipated expiration: 2017-09-11
Also published as: NZ299357A; AU3749797A

Description

I

48017 GEH:LL P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

a S Name of Applicant: a FORMWAY FURNITURE LIMITED Actual Inventor: ROBERT BRUCE STEWART Address for Service: COLLISON CO.,117 King William Street, Adelaide, S.A. 5000 Invention Title: IMPROVEMENTS IN/OR RELATING TO METHODS OF STRENGTHENING DESK TOPS AND/OR APPARATUS USED THEREFOR The following statement is a full description of this invention, including the best method of performing it known to us:

-IA-

IMPROVEMENTS IN/OR RELATING TO METHODS OF STRENGTHENING DESK TOPS AND/OR APPARATUS USED THEREFOR This invention relates to methods of strengthening desk tops and/or apparatus used in such strengthening.

Tables and desks are required to support a significant loading and the top requires strengthening which can be achieved using an appropriate support frame carried on the legs.

In commercial applications, particularly for desks, it is desirable to leave the undersurface of the top as free from obstructions as possible. In a modern office, a desk top is often required to support quite heavy equipment, such as computers etc. Both for the efficiency of the equipment operation and the safety of users, standards have been introduced to restrict the permissible deflection in desk or table tops. To keep within the imposed standards it has been necessary to provide strengthening frames, usually metal frames beneath the top of the desk or table but such frames can be inconvenient to a user and also are expensive to manufacture.

In the present specification the term "desk top" is intended to encompass any planar top such as a table or bench, which may be employed in circumstances where the present invention would have applicability.

It is an object of the present invention to provide a method of strengthening desk tops and/or apparatus used in such strengthening which will enable the top to meet the required standards for the deflection without major supporting framework members extending across or along the table in a position likely to be inconvenient to users.

Accordingly, in one aspect the invention consists in a method of strengthening a desk top, said :method comprising the steps of: forming two anchor means extending in from the undersurface •30 of the desk top, said anchor means being spaced towards opposite edges of said desk top; providing a tensioning means on the undersurface of the desk top, the tensioning means extending under axial tension between the two anchor means to retain a tension on the undersurface of the desk top resisting downward deflection of the desk top in use.

Preferably, approximately 2 mm ofpre-tension is provided for each metre length of the tensioning means.

-Ib- In a second aspect the invention consists in a desk top including: an undersurface having two inwardly extending anchor means, said anchor means being spaced towards opposite edges of said desk top; and a tensioning means on the undersurface of the desk top, the tensioning means extending under axial tension between the two anchor means; such that downward deflection of the desk top in use is resisted by tension provided on the undersurface by the tensioning means.

One preferred form of the present invention will now be described with reference to the accompanying drawings in which: p.

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-2- Figure 1 is a side view of strengthening apparatus according to the present invention; Figure 2 is a plan view of Figure 1; and Figure 3 is a section through a desk top showing the strengthening apparatus fitted in place.

The present invention is designed to provide pre-tensioning on the undersurface of the desk top so that any downward deflection caused by a load on the desk top will be resisted by the pre-tensioning member. It is important to ensure that when the pre-tensioning member is installed it will function throughout the useful life of the desk top and hence it is important that the anchor means are arranged to minimise any distortion or creep which will reduce the effectiveness of the method of strengthening according to the present invention.

With these broad parameters in mind, a table or desk top 1 has formed therein anchor apertures 2 and 3 towards opposite edges of the desk, usually on a longitudinal axis. The anchor apertures 2 and 3 should be as widely spaced as may conveniently be achieved on the undersurface of the desk top 1. The apertures 2 and 3 are formed so that the adjacent 20 faces are substantially at right angles to the undersurface and thus effectively provide abutment surfaces 4 and 5. If the material used in the desk top has sufficient hardness, these untreated surfaces will provide the anchor abutment faces which will avoid creep when the tension strap is fitted in place, but in some applications it maybe necessary or desirable to reinforce or strengthen these abutment surfaces.

The manner of achieving the desired resistance to movement or deflection during use will depend upon the material used in the desk top 1. If the material in the desk top 1 is subject to compression under load, the surfaces 4 and 5 may need to be hardened. One method of achieving this is by pre-compression of the surfaces, for example, by oo 30 overloading during positioning of the tension strap.

As indicated above, another method would be by adding a hardening material which may be as simple as providing a coat of paint on the surface of the aperture, but impregnation with epoxy resins or other surface coating could also be employed. However, while these techniques maybe necessary in composite tops, it is unlikely that they would be required in timber tops.

The strengthening apparatus used comprises a tension strap 6, for example, a 65 mm by 3 mm mild steel strap. Higher grade steel could of course be used and the dimensions may be varied depending upon the size of the desk and other requirements. Normally, the -3design would be arranged to achieve the desired result but with a minimum of material cost.

Towards each end of the strap 6 are fixed on one surface of the strap anchor blocks 7 and 8. The anchor blocks, are preferably rectangular blocks having anchor surfaces 9 and to engage against the abutment surfaces 4 and 5 in the anchor apertures 2 and 3.

We have found it is desirable for the anchor blocks 7 and 8 to have a width of approximately 200 mm and a depth of 10 mm. Thus the anchor blocks project from each side of the strap 6 and the anchor apertures 2 and 3 will be formed to receive these blocks.

Again these dimensions are given by way of example and are not intended to be limiting.

The strap 6 desirably extends beyond the anchor blocks 7 and 8 and has apertures 11 therethrough to allow fixing screws 12 to pass to the undersurface of the desk top and locate the strengthening apparatus in position.

The desk top with the anchor apertures formed appropriately positioned relative to the dimensions of the strap is then deformed away from the anchor apertures 2 and 3, that is bowed upwardly until the anchor blocks 7 and 8 will engage in the apertures 2 and 3 and the complementary abutment surfaces 4, 5, 9 and 10 engage. The dimensions and positioning of the anchor apertures 2 and 3 and the anchor means on the strap 6 will be such that when installed the strengthening apparatus will provide a tensioning, but the desk top 1 will return essentially to the planar position.

6 ^As a guide the bowing of the desk top has to be such that approximately 2 mm of pretensioning is provided for each metre length of the tensioning member. This is achieved by increasing the bow in the desk top 1 which, as will be apparent, enables the anchor blocks to engage in the anchor apertures 2 and 3.

oo* While it is convenient to bring the tensioning member closer to the desk top so that the anchor blocks engage within the anchoring recesses by bowing the desk top upwardly, any means of ensuring the strengthening apparatus is able to provide the required pretensioning would be acceptable.

In this way a very simple and yet effective way is provided for strengthening desk tops without the incumberence of supporting framework members extending along under the AN urfface of the desk top.

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Claims

1. A method of strengthening a desk top, said method comprising the steps of: forming two anchor means extending in from the undersurface of the desk top, said anchor means being spaced towards opposite edges of said desk top; providing a tensioning means on the undersurface of the desk top, the tensioning means extending under axial tension between the two anchor means to retain a tension on the undersurface of the desk top resisting downward deflection of the desk top in use.

2. A method as claimed in claim 1 wherein each of the two anchor means is formed to include an abutment face against which a respective complementary abutment means on the tensioning means will engage.

3. A method as claimed in claim 1 or 2 wherein recesses are formed in the undersurface of the desk top to provide the two anchor means with each of said recesses including an abutment face to be engaged by a corresponding abutment means on the tensioning means.

4. A method as claimed in claim 1 wherein said tensioning means comprises a metal strap with two anchor engaging means on said strap to engage with said two anchor means on the undersurface of the desk and retain a tension in said strap when located in position. A method as claimed in claim 2 or 3 wherein said tensioning means comprises a metal *strap with two anchor engaging means on said strap defining said abutment means to engage with said abutment faces and retain a tension in said strap when located in position. A method as claimed in any one of the preceding claims wherein the desk top is deformed to form a concave undersurface to allow the tensioning means to be engaged with the anchor means to provide the desired tension on the undersurface of the desk top.

7. A method as claimed in any one of the preceding claims wherein approximately 2 mm of pre-tension is provided for each metre length of tensioning means.

8. A method of strengthening a desk top when performed substantially as herein described with reference to the accompanying drawings. **o

9. A desk top including: an undersurface having two inwardly extending anchor means, said anchor means being spaced towards opposite edges of said desk top; and a tensioning means on the undersurface of the desk top, the tensioning means extending under axial tension between the two anchor means; such that downward deflection of the desk top in use is resisted by tension provided on the undersurface by the tensioning means. A desk top as claimed in claim 9 wherein each of the two anchor means includes and abutment face against which a respective complementary abutment means on the tensioning means is engaged.

11. A desk top as claimed in claim 9 or 10 wherein the two anchor means are in the form of recesses in the undersurface, with each recess including an abutment face against which a corresponding abutment means on the tensioning means is engaged. a i

12. A desk top as claimed in claim 9 wherein said tensioning means comprises a metal strap with two anchor engaging means on said strap being engaged with said anchor means on the undersurface of the desk, thereby retaining a tension in said strap.

13. A desk top as claimed in claim 10 or 11 wherein said tensioning means comprises a metal strap with two anchor engaging means on said strap defining said abutment means which are f engaged with said abutment faces, thereby retaining a tension in said strap. oo°°

14. A desk top as claimed in claim 12 or 13 wherein each of said two anchor engaging means comprises an anchor block attached towards a respective end of said strap. A desk top as claimed in claim 14 wherein each anchor block extends across the strap to project from each side of the strap. 4* -6-

16. A desk top as claimed in claim 14 or 15 wherein the tensioning strap extends beyond the anchor blocks to define apertures, the tensioning strap being attached to the undersurface of the desk top via fastening screws through said apertures.

17. A desk top as claimed in any one of claims 9 to 16 wherein approximately 2 mm of pre- tension is provided for each metre length of the tensioning means.

18. A desk top substantially as hereinbefore described with reference to the accompanying drawings. Dated this 2nd day of January 2001 FORMWAY FURNITURE LIMITED By their Patent Attorneys COLLISON CO *es