GB2173227A

GB2173227A - Grid system for suspension ceiling

Info

Publication number: GB2173227A
Application number: GB08507043A
Authority: GB
Inventors: Richard Sommers Daly
Original assignee: SPECIAL ACOUSTIC SERVICES LIMI
Current assignee: SPECIAL ACOUSTIC SERVICES LIMI
Priority date: 1985-03-19
Filing date: 1985-03-19
Publication date: 1986-10-08
Also published as: GB8507043D0

Abstract

A composite grid support member 1 for a suspended ceiling system comprising a sheet metal support blade 2 capped with a separate base 5 of an extrudable material (such as aluminium or fire resistant plastic) having a longitudinally extending channel or slot 6 in it. The slot is preferably an open channel whose side walls have parallel ribs 7 on them to receive and locate a screw therein. The support blade is preferably cold rolled mild steel. <IMAGE>

Description

SPECIFiCATION Grid System for Suspension Ceiling This invention relates generally to grid systems for suspension ceilings or the like, and more particularly, to an improved grid system for such ceilings which includes a mounting slot which runs continuously throughout. The invention also relates to an improved grid member for use with said grid system.

Grid systems for suspension ceilings incorporating a continuous mounting slot are known, such systems being used not only to support the ceiling panels but also to locate and hold in position partition walls etc. These systems generally fall into two categories, the first of which uses a T-section grid member of rolled steel whose base is formed so as to provide a slot in which a T-bolt fastener may be located, the partition walls or other attachments being secured to the grid members by means of these T- bolt fasteners. The problem with such systems is that they are expensive to manufacture because of the complex profiles which have to be rolled and it is very expensive to produce a range of widths of grid member because a new set of cold rolling dies costing several thousand pounds is needed for each profile.Also, each T-bolt needs to have a nut attached to it to secure the partition or other attachment to the grid member which is very time consuming. An important advantage however of these rolled steel grid members is that they can fairly readily be made to comply with the official fire regulations fairly readily, which for instance require that should a fire occur, the whole ceiling structure will not collapse due to buckling for a period of, say, one hour.

The second known system uses an extruded aluminium T-section grid member whose base includes a slot to receive and hold a locating screw therein, the slot having parallel ribs extending longitudinally along its opposite side walls so that the screw to retain a partition or other attachment can be screwed directly into it. This system has the advantage that it is much easier to attach the partition etc to the erected ceiling grid system because only single screws rather than two part T-bolts and nuts are used. Furthermore, and more importantly, the aluminium grid members are much easier and cheaper to produce as the extrusion dies cost hundreds rather than thousands of pounds.

This means that a wide range of width sizes of grid member can be provided at a relatively low tooling cost and certainly at a fraction of the tooling cost of providing the same range of sizes in rolled mild steel. The problem however with extruded aluminium grid systems is that it is difficult to get them fire rated because the aluminium extrusions melt so easily in the event of a fire.

It is an object of the invention therefore to provide a slotted grid system which is cheap to produce and which can be readily fire rated.

According to the invention, there is provided a composite grid support member for use in a suspension ceiling system comprising an elongate metal support member capped with a separate base of an extrudable material.

Preferably, the base has a longitudinally extending slot or channel in it.

Desirably the base is made of an alloy and is removably attached to the steel support blade. In a preferred embodiment, the support member is a rolled mild steel blade of an inverted Tee-Section with laterally extending feet, the base having parts adapted to cooperate with the laterally extending feet of the support member to retain the base thereon.

Conveniently, the base is of extruded aluminium but any suitable alloy capable of extrusion can be used. For some applications, an extruded fire resistant plastics material could be used.

Preferably the slot in the base is an open channel with parallel ribs extending along the facing side walls thereof, said ribs being adapted to receive and locate a screw therein.

The width of the base can be varied in several ways. For instance, if it is desired to provide a range of widths from 16mm through 25mm to 40mm, the steel support blade can be rolled so as to have laterally extending feet of those dimensions and then specifically dimensioned extruded bases can be fitted on to them. Alternatively, one standard width steel support blade could be used and extruded bases of different widths could be attached to it.

Another feature of the invention is that when a grid support system is made up from connected lengths of grid support member of the invention, the junctions between intersecting grid members ofthe system can be mitred joints so that a continuous slot or channel can be provided throughout the whole grid system. Full details of the manner in which the base members can be cut to provide the mitred joints just referred to will not be described further here as full details thereof are given in our copending Application No. 8334265 to which the reader is referred.

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a cross-section through a preferred capped grid member of the invention; Figure 2 is a cross-section through another capped grid member of the invention; Figure 3 is a cross section through a capped grid member similar to that of Figure 2 using the same steel support blade but a wider extruded base; Figure 4 shows how a grid member can be provided with three different width bases; and Figure 5 shows how a grid member of the invention can be juxtaposed with a light box unit in a suspended ceiling system.

Referring to Figure 1 of the drawings, there is shown a grid support member 1 which comprises a cold rolled mild steel support blade 2 made up from one piece of steel shaped to include a bulb 3 at its top end and laterally extending feet 4 at its base.

Whilst the profile shown in the drawings is preferred, any required shaped profile could be used although it should preferably be generally of an inverted T or L- cross section including the laterally extending feet 4. An extruded alloy base 5 is fitted onto the support blade 2 in the manner illustrated. The alloy base is provided with an open slot or channel 6 provided along its facing side walls with parallel ribs 7. It also includes two inwardly directed lips 8 which co-operate with the feet 4 of the support blade 2 to enable the alloy base to be retained thereon. In practice, the alloy base 5 would be slid on to the support blade 2.

Instead of using the method of attaching the alloy base 5 to the support blade 2 shown in Figure 1, the alloy base could include a pair of spaced inwardly directed lips 9, 10 along its opposite edges between which the feet 4 of the support blade 2 can be fitted.

The alloy base 5 would be fitted to the support blade 2 in the same way as already described by sliding the lateral feet 4 into the channels formed between the lips 9 and 10; The width of the alloy base member 5 can be varied and fitted to the feet 4 of a standard width support blade as shown in Figure 3. It will be appreciated from the drawing that with this arrangement, provided the distance Y between the mounting slots 9', 10' remains constant, the width X of the base 5 as a whole can be varied to suit by extruding it to any appropriate width.

Figure 4 shows diagrammatically an alternative way of varying the width of the base 5 using three different width support blades 2 and 3 appropriately dimensioned extruded alloy bases 5 fitted to them.

With the illustrated arrangements, three different support blades would have to be cold rolled in each case to provide feet 4 of the appropriate width.

Similarly, three appropriately dimensioned alloy bases 5 would have to be extruded to fit on to the feet 4 of the support blades.

Figure 5 shows how the grid support members 1 can be abutted against a light box assembly 15.

Claims

1. A composite grid support member for use in a suspension ceiling system comprising an elongate support member capped with a separate base of an extrudable material.

2. A composite grid support member as claimed in claim 1 wherein the case has a longitudinally extending slot or channel in it.

3. A grid support member as claimed in claim 1 or claim 2, wherein the base is made from an aluminium alloy material.

3. A grid support member as claimed in claim 1 or claim 2, wherein the base is made from an alloy material such as aluminium.

4. A grid support member as claimed in any of claims 1 to 3 wherein the support member is a steel blade of rolled mild steel.

5. A grid support member as claimed in any of the preceding claims, wherein the base is removably attached to the support member.

6. A grid support member as claimed in any one of the preceding claims wherein the support member is of an inverted T-section, the base having parts adapted to cooperate with the laterally extending feet of the support member to retain the base thereon.

7. A grid support member as claimed in any one of the preceding claims wherein the slot in the base is an open channel with parallel ribs extending along the facing walls thereof.

8. A grid support member as claimed in claim 6 wherein the base has a pair of upstanding side walls, each of which has an inwardly directed lip shaped to engage with the feet of the support member.

9. A grid support member as claimed in claim 8 wherein a second unwardly directed lip is formed on each upstanding side wall to provide a slot into which the laterally extending feet of the support member fit to attach it to the base.

10. A grid support member substantially as herein described with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1,2 and 3 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows:- 1,2 and 3

1. A composite grid support member for use in a suspension ceiling system comprising an elongate rolled sheet metal support member capped with a separate base of an extruded metal alloy material.

2. A composite grid support member as claimed in claim 1 wherein the base has a longitudinally extending slot or channel in it.