GB2123687A

GB2123687A - Demountable chair base

Info

Publication number: GB2123687A
Application number: GB08220196A
Authority: GB
Inventors: Raymond R J Daniels
Original assignee: Guy Raymond Engineering Co Ltd
Current assignee: Guy Raymond Engineering Co Ltd
Priority date: 1982-07-12
Filing date: 1982-07-12
Publication date: 1984-02-08
Also published as: DK162014C; IT8335943V0; NO160325B; SE8303876L; DK321483A; GB2123687B; SE8303876D0; NO832473L; IT1170436B; DK162014B; NO160325C; IT8348650A0; DK321483D0; DE3324981A1

Abstract

A chair base comprising a boss 11, a central bore 16 in the boss adapted to receive a chair supporting pillar removably mountable in the bore, a plurality of tubular spokes 12 and a ground engaging member such as a castor 13 removably attached to each spoke for supporting the chair base, characterised in that the boss is formed with a plurality of generally radially extending sockets 18 and a spoke is removably mounted in each socket. The spokes may be held in position by threaded fasteners which extend through a metal strengthening plate attached to the underside of the boss. <IMAGE>

Description

SPECIFICATION Demountable chair base The present invention is concerned with a demountable chair base.

It is known to provide a chair base comprising a central boss and a plurality of spokes extending radially outwardly from the boss and each carrying at its end a wheel or castor for supporting the chair on the ground. In this known design of chair base, the pillar which supports the chair seat may be rigidly or removably attached to the boss.

However, because of the weight which the chair base has to support, hitherto the spokes have always been integral wither permanently attached to the boss so that the chair base comprising the boss and radially extending spokes had to be stored and transported as a single assembled unit.

It is therefore an object of the present invention to provide a chair base which is demountable into its separate components for storage and transport and which can be quickly and easily assembled to form a rigid and strong chair base on site without the need for any special tools or skills.

According to the present invention there is provided a chair base comprising a boss, a central bore in the boss adapted to receive a chair supporting pillar removably mountable in the bore, a plurality of tubular spokes and a ground engaging member removably attached to each spoke for supporting the chair base, characterised in that the boss is formed with a plurality of generally radially extending sockets and is removably remounted in each socket.

Preferably, each spoke is locked in its respective socket by fastening means which engage the underside of the spoke.

In a preferred embodiment of the invention, the boss comprises a main body and a metal strengthening plate attached to the underside of the main body and preferably the fastening means comprises a threaded fastener which extends through the plate and the bottom walt of a respective socket and which is threadedly engaged in the respective spoke to clamp the plate, body and spoke together.

The plate may have a peripheral lip which overlaps the body and engages in a slot in each spoke to wedge the spoke into the socket.

Preferably each socket has an end wall and each spoke is a close fit within its respective socket and buts against the end wall to form a solid connection between the boss and the spoke.

In use, a vertical load placed on a pillar mounted in the boss is transmitted through the fastening means to the plate and will exert a rotative force on the spoke which clamps the spoke more tightly against the end of the socket to form a strong and rigid assembly.

An embodiment of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a demountable chair base according to the present invention partly assembled; Figure 2 is a plan view of the chair base shown in Figure 1; Figure 3 is a section taken on the line Ill-Ill of Figure 2; Figure 4 is a section taken on the line lV-IV of Figure 3; Figure 5 is a plan view from below of the tube end insert shown in Figure 3; Figure 6 is a side elevation of the insert shown in Figure 5; Figure 7 is a section, similar to Figure 3, showing a modification of the boss; Figure 8 shows a detaii of Figure 7 on an enlarged scale;; Figure 9 is a view similar to Figure 2 showing an alternative embodiment of the chair base of the present invention; Figure 10 is a section through yet a further embodiment of the present invention; and Figure 11 is an elevation through yet a further embodiment of the present invention.

In Figures 1 to 4, a chair base is indicated generally at 1 0. The chair base 10 comprises a boss 11 and a plurality of spokes 12, each of which carries a ground engaging member in the form of a castor 13.

The boss 11 may be made from any suitable material and in the embodiment illustrated in Figures 1 to 4 comprises a main body 14 made as an injection moulding from a tough synthetic plastics material such as nylon and a steel plate 15. The body 14 of the boss is formed with a central bore 16 which is tapered to receive a conventional chair supporting pillar 17. The pillar 17 may be a gas action height adjustable pillar and may be mounted in the bore 1 6 as a friction fit. The body 14 of the boss is also formed with five similar and equi-anguiarly spaced radially extending sockets 1 8 to receive the spokes 12.

Each spoke 12 is formed from sheet steel and is of generally rectangular section tubular shape. The dimensions of each spoke 1 8 are such that its inner end is a close push fit within the bore of its respective socket 1 8.

The outer end of each spoke 1 2 is closed by a tube end insert 19 which may be a plastics moulding or a die-casting. Each insert 19 has a main body 20 which is a close fit with the end of the tube and an end flange 21 which buts against the end of the tube. The body 20 of the insert 19 is formed with a bore 22 which aligns with an aperture 23 in the bottom wall of the spoke 12 adjacent the end of the spoke. Each castor 1 3 includes a conventional vertical spigot 24 which is a push fit through the aperture 23 in the spoke, into the bore 22 in the insert where it is retained by the frictional grip exerted on the spigot 24 by the plastics material of the insert.

In order to assemble a spoke 12 with the boss 11 the inner end of the spoke 12 is pushed home into a socket 1 8 so that the end of the spoke buts against an end wall 25 of the socket. In this position a threaded screw receiving aperture 26 in the bottom wall of the spoke is aligned with an aperture 27 in the bottom wall of the socket 18.

When the spokes are in position, the steel plate 1 5 is placed against the bottom of the body 14 of the boss where it is located in position by a lip 28 on the body of the boss.

The steel plate 15 is formed with a plurality of apertures 29 which will align with the apertures 27 in the body 14. With the apertures 29 in the plate aligned with the apertures 27 in the body 14, a screw can be passed through each aligned pair of apertures 29 and 27 and threaded into the screw receiving aperture 26 in the spoke 12 to lock each spoke in position in its respective socket.

When a spoke has been locked in position in each of the five sockets 18 and the pillar 17 assembled in the boss, a downward force exerted on the pillar 17, as for instance by a person sitting on the chair, will be transmitted through each spoke to the steel plate 1 5 which will carry a major part of the load exerted on the boss and the spokes. By virtue of the close fit on each spoke in its socket 1 8 and the locking action of the screw 30 which clamps the steel plate, the body of the boss and the spoke together, an extremely rigid and solid assembly is achieved which can withstand very substantial weights.

It will be seen that the components of the chair base 10, comprising the boss 11, spokes 12 and castors 13 can be packed and transported in a demounted condition in approximately one quarter of the space required for the assembled chair giving very substantial transport and storage cost savings. The components can then be assembled on site with a minimum of time and labour by simply slotting the spokes into the boss, placing the plate in position, inserting and threading home the screws and then assembling the tube end inserts and the castors in place. The chair base 10 is then fully assembled and ready to receive the chair supporting pillar 1 7.

In an alternative embodiment of the invention, which is indicated generally at 30 in Figures 7 and 8, a steel plate 31 is provided with a peripheral lip 32 which locates in a slot 33 formed in each spoke 34. As can be seen from Figure 8, the end face 35 of the slot 33 which is engaged by the lip 32 of the steel plate is inclined at an angle of approximately 120 to the vertical so that the lip 32 exerts a wedging action on the spoke 34, forcing the spoke against the end wall of the socket in which it is located. The provision of a lip therefore has the effect of ensuring a solid immovable connection between the boss and the spoke.

The spokes of the chair base may be made of any suitable material such as steel or reinforced plastics although sheet steel is the preferred material. They may also be made of any desired cross-sectional shape and they may also be made as a composite of different materials. An embodiment comprising composite materials is indicated generally at 40 in Figure 9 which shows a circular boss 41 having five sockets 42 to receive spokes 43. Each spoke 43 has a core 44 made from tubular steel and a coating 45 of polyurethane or alternative synthetic plastics material. The steel core 44 projects beyond the coating 45 to form a spigot 46 which is inserted into the receiving socket 42. In all other respects, the chair base 40 is similar to the chair base 10 and is assembled and disassembled in the same way.

It is also envisaged that the boss may be made of any suitable material. A further embodiment of the present invention is illustrated in Figure 10 which illustrates a boss 51 which is made of a metal casting to receive spokes 52, each of which comprises a solid metal bar. The boss 51 is formed with a plurality of sockets 53 each of which receives a spoke 52. The bottom wall of each socket 53 is formed with a threaded aperture 54 to receive a grub screw 55 which locks the spoke 52 in position within the socket 53.

In yet a further embodiment of the invention, which is illustrated in Figure 11 , a boss 60 is provided with a plurality of sockets 61 which are H-shaped in cross section and adapted to receive spokes 62, each of which is in form of an H-section steel bar. Each spoke 62 is a close fit within a receiving socket 61 and is locked in position with the aid of a grub screw, not shown, but similar to the grub screw described in relation to Figure 10.

It will be seen from the drawings and description herein, that both the spokes and the boss can be made of different shapes and materials provided that, each spoke is a close fit within a receiving socket in the boss and is locked in position by fastening means positioned in the bottom wall of the socket and adapted to exert an upward clamping action on the spoke to urge the spoke tightly against the end of the socket. This ensures that a vertical load placed on the boss is transmitted through the fastening means to the boss so as to exert a rotative force on the spoke which clamps the spoke more tightly against the end of the socket. In this way the present invention ensures that the chair base, although readily demountable, is sufficiently strong to take the maximum weight which is likely to be applied to a chair supported on the chair base.

Claims

1. A chair base comprising a boss, a central bore in the boss adapted to receive a chair supporting pillar removably mountable in the bore, a plurality of tubular spokes and a ground engaging member removably attached to each spoke for supporting the chair base, characterised in that the boss is formed with a plurality of generally radially extending sockets and a spoke is removably mounted in each socket.

2. A chair base as claimed in claim 1, characterised in that the fastening means engage the underside of the spoke.

2. A chair base as claimed in claim 1, characterised in that each spoke is locked in its respective socket by fastening means which engage the underside of the spoke.

3. A chair base as claimed in claim 1 or claim 2, characterised in that the boss comprises a main body and a metal strengthening plate attached to the underside of the main body.

4. A chair base as claimed in claim 3, characterised in that the fastening means comprises a threaded fastener which extends through the plate and the bottom wall of a respective socket and which is threadedly engaged in the respective spoke to clamp the plate, body and spoke together.

5. A chair base as claimed in claim 3 or claim 4, wherein the plate has a peripheral lip which overlaps the body and engages in a slot in each spoke to wedge the spoke into the socket.

6. A chair base as claimed in any preceding claim, wherein each socket has an end wall and each spoke is a close fit within its respective socket and buts against the end wall.

7. A chair base as claimed in any preceding claim, characterised in that each spoke is formed from sheet metal.

8. A chair base as claimed in any preceding claim characterised in that the main body of the boss is a plastics moulding.

9. A chair base comprising a boss, a central bore in the boss adapted to receive a vertical chair supporting pillar removably mountable in the bore, a plurality of generally radially extending stopped sockets in the boss each having an end wall, a tubular metal spoke removably mounted as a close fit in each socket, and abutting the end wall and a ground engaging member attached to each spoke for supporting the chair base on the ground, characterised in that the boss comprises a main body and a metal strengthening plate clamped to the underside of the body and in that each spoke is locked in its respective socket by fastening means which extend through the plate and the wall of the socket whereby a vertical load placed on the pillar is transmitted through the fastening means to the plate and will exert a rotative force on the spoke which clamps the spoke more tightly against the end of the socket.

1 0. A chair base substantially as described herein with reference to the accompanying drawings.

New claims or amendments to claims filed on 21.7.83.

Superseded claims 1 and 2.

New or amended claims:

1. A chair base comprising a boss, a central bore in the boss adapted to receive a chair supporting pillar removably mountable in the bore, a plurality of tubular spokes and a ground engaging member removably attached to each spoke for supporting the chair base, characterised in that the boss is formed with a plurality of generally radially extending sockets and each spoke is removably mounted in each socket by its own separate fastening means.