GB2282754A - Modular chair frame - Google Patents

Abstract

A chair frame comprises at least one chair side piece 10 which is adapted to be secured to a modular accessory 11, 12 such as a chair wing or chair arm. In this way a single side piece shape may be used to produce a variety of chair shapes by adding one or more modular accessories. Each side piece has a number of blind sockets 17 for receiving transverse structural members 18 of the chair. <IMAGE>

Description

Chair frame This invention relates to frames for upholstered furniture such as chairs and settees.

Upholstered furniture such as chairs and settees is made by building a frame, and then attaching springs across certain parts of the frame to provide a sprung seat base and back, for example. The frame usually comprises two side pieces, which may form the arms and wings of the furniture, if present, connected together by cross rails which form the back and bottom of the frame.

The side pieces are conventionally made from such materials as wood or, more commonly for mass produced furniture, from chipboard, plywood or fibreboard because such materials are relatively inexpensive. However, in order to form the shapes required for a particular style of furniture, it is necessary to machine blocks of material to the required shape. This operation may be relatively time consuming and the nature of the materials may make certain styles of furniture difficult or impossible to make, especially if the style of furniture required incorporates curved or complicated shapes.

One alternative is to mould the side pieces from plastics materials which are relatively cheap and which, by shaping a mould appropriately, allow many different shapes to be produced. Also a plastics frame is likely to be stronger and more robust than a frame made from chipboard and ply materials. However a mould for e.g. injection moulding a side piece is expensive to design and make and so the economy of scale is such that many thousand pieces must be made from that mould before the cost of each piece is competitive against chipboard and such materials. Since the style of such furniture is dictated largely by the shape and design of the side pieces, the freedom to produce different styles of furniture is restricted using such moulded pieces because only a very limited number of shapes are likely to be available, owing to the cost of making each mould.

It is an object of the invention to provide a chair frame which overcomes some, at least, of the foregoing problems.

A chair frame according to the invention comprises at least one chair side piece adapted to be secured to a modular accessory such as a chair wing.

The chair side piece preferably includes an arm structure and is preferably formed with one or more strengthening ribs arranged generally vertically within that part of the side piece intended to form the arm structure. Most preferably the strengthening ribs abut a generally horizontal member having, on the inner surface of the chair side pieces a generally vertical surface to which an overlying material such as fibreboard may be secured, by stapling for example.

The side piece is preferably provided with a number of blind sockets, the axis of each socket being directed generally horizontally, and opening at the inner surface of the side piece.

Each socket is proportioned so as to be able to receive an end of a frame cross-rail which extends between two side pieces. Most preferably the inner surface of each socket is provided with a plurality of axial ribs, preferably tapered towards the opening of the socket. The ribs provide a secure housing for a cross-rail end by engaging the outer surface of the cross-rail as it is inserted into the socket thereby forming an interference fit. Each socket may preferably be provided with an aperture in its blind end through which air may escape when a cross-rail is being inserted into a socket. The number of sockets provided in a side piece may be varied, but most often there will be five or six sockets placed to house the front and back base frame rails, the front and back seat cushion rails and the bottom back rail.A socket to house the top back rail may also be present in the side piece or may be provided on a modular accessory which forms a chair wing, if present.

The modular accessories may comprise a chair wing piece, an arm stump piece or a piece to extend or change the shape of the chair side piece. A modular arm stump piece for example, may take the form of a fall-back arm stump, for example, which may fit between the arm structure of the side piece and the front end of the side piece.

A modular arm stump may be decoratively finished or may be intended to be covered when the chair, for example, is upholstered. An arm stump may be a full front arm stump if the front end of the side piece is a generally vertical surface extending the full height of the side piece. The modular accessories may be provided with a socket to receive an end of a cross-rail.

By selecting the appropriate modular accessories and a side piece, a number of different styles of chair or settee may be made from a limited number of differently moulded pieces, thus allowing greater freedom for furniture designers using moulded plastics frames.

The modular accessories may be secured to the chair side piece by bolts, clips or by snap-type fastenings which may optionally be integral with the side piece and/or the modular accessory to be secured. Alternatively the accessories or the side piece may be provided with a slot into which a tongue mounted upon the side piece or accessory may be fitted to secure the one to the other.

The chair side piece and modular accessories are preferably made from a plastics material such as polypropylene, polyethylene or polystyrene and are preferably made by injection moulding, although other moulding techniques such as low pressure structural foam moulding or rotational moulding may be used.

A preferred embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawing which is an exploded perspective view of a chair frame according to the invention.

The chair frame in the drawing comprises side pieces 10, a modular wing piece 11 and a modular arm stump 12. Only one wing piece and arm stump are shown, for clarity, although it would be usual to build a symmetrical frame.

The side pieces 10, formed in polypropylene by injection moulding, have reinforcing ribs 13 in the region of the arm structure 14. The ribs 13 extend upwardly from a horizontal surface 15 adjacent a vertical surface 16 of the inner side of side piece 10. When the chair is upholstered, a piece of fibreboard may be placed over the arm, curved around the upper and side edges of the ribs 13 and fastened to vertical surface 16 by stapling. Sockets 17 are formed integrally with the side piece 10 and wing piece 11 and are of a suitable size and shape to be able to receive, snugly, an end of a cross-rail 18.

The sockets have a number of axial ribs 19 located around the inner surface of each socket. The ribs 19 are slightly taller and wider towards the rear of the socket than near the opening and taper along their lengths. These ribs 19 bite into a crossrail 18 as it is forcibly inserted into a socket 17 and thereby provide for secure location of a crossrail within a socket.

In the form shown, the side piece 10 has an arm structure 14 which which does not extend the full length of the side piece, leaving a horizontal surface 20 extending forwards of the arm structure.

In this form a frame built from such side pieces is suitable for receiving T-shaped seat cushions, an arm of the T of the cushion extending over surface 20. However, by the addition of the modular arm stump 12, mounted upon surface 20, a frame for a different style of chair is achieved. Similarly, if a high backed style of chair is required then the fixing of modular wing piece 11 to the frame provides a wing and a socket 17 to receive a top back cross-rail. In this example the wing rail 21 is received into a recess 22 in side piece 10, although it would also be possible to provide a wing rail integral with side piece 10 to which a modular wing piece would be fitted. It will be understood that several different designs of modular arm stumps and/or modular wing pieces may be available giving the possibility of making many different types of frame from combinations thereof and thereby making many styles of furniture possible. The invention therefore allows the furniture designer at least the flexibility of using wood or chipboard frames coupled with the advantages of using moulded plastics frames.

Claims (16)

1. A chair frame comprising at least one chair side piece adapted to be secured to a modular accessory.

2. A chair frame as claimed in Claim 1, wherein said chair side piece includes an arm structure.

3. A chair frame as claimed in Claim 2, wherein said side piece comprises at least one strengthening rib arranged generally vertically within a part of the side piece which is intended to form the arm structure.

4. A chair frame as claimed in Claim 3, wherein said rib abuts a generally horizontal member, which member has a generally vertical surface disposed on the inner surface of the side piece.

5. A chair frame as claimed in any of the preceding claims, wherein said side piece has a plurality of blind sockets opening at the inner surface of said side piece, the axis of each said socket being directed generally horizontally.

6. A chair frame as claimed in Claim 5, wherein the inner surface of each socket has a plurality of axial ribs.

7. A chair frame as claimed in Claim 6, wherein said ribs are tapered towards the opening of the socket.

8. A chair frame as claimed in any of claims 5-7, wherein each of said sockets has an aperture in its blind end.

9. A chair frame as claimed in any of the preceding claims, wherein said modular accessory comprises a chair wing piece, an arm stump piece or a piece for extending or changing the shape of said chair side piece.

10. A chair frame as claimed in any of the preceding claims, wherein said modular accessory has a socket.

11. A chair frame as claimed in any of the preceding claims, wherein said modular accessory is secured to said chair side piece by means of bolts, clips or snap-fastenings.

12. A chair frame as claimed in Claim 11, wherein said modular accessory is secured to said chair side piece by securing means which are integral with either or both of the side piece and/or modular accessory.

13. A chair frame as claimed in any of Claims 1 to 10, wherein said modular accessory is secured to said chair side piece by means comprising a slot and a tongue for engagement in said slot, each located in or on one of the side piece or the modular accessory.

14. A chair frame as claimed in any of the preceding claims, wherein said side piece and said modular accessory are made from a plastics material.

15. A chair frame as claimed in Claim 14, wherein said plastics material is polypropylene, polyethylene or polystyrene.

16. A chair frame substantially as hereinbefore described with reference to and as shown in the accompanying drawing.