AU729048B2

AU729048B2 - Chair base

Info

Publication number: AU729048B2
Application number: AU44365/97A
Authority: AU
Inventors: Lance Wasson
Original assignee: DYNAFURN A DIVISION OF LINCOLN
Current assignee: DYNAFURN A DIVISION OF LINCOLN SENTRY GROUP Pty Ltd; WASSON PLASTICS SALES Pty Ltd
Priority date: 1996-11-05
Filing date: 1997-11-05
Publication date: 2001-01-25
Anticipated expiration: 2017-11-05
Also published as: AU4436597A

Description

AUSTRALIA

Patents Act 1990 Wasson Engineering Plastics and Dyniaic Furniture Components Pty Ltd DR~)R~'J R t)T\Jro. OF LILt-jCOyj- &AiT9I0-ove Prf LVD.

ORIGINAL

R

S104 4 COMPLETE SPECIFICATION %O STANDARD PATENT a Invention Title: a.

a Chair base The following statement is a full description of this invention including the best method of performing it known to us:- Field of Invention The present invention relates to a chair base and, in particular, to a chair base for a swivel chair.

Background of the invention Bases for swivel chairs are normally either be made of moulded plastic material,' such as fibreglass reinforced nylon.. known as glass filled nylon, or metal. Swivel chair bases are commonly star shaped. One common design has five arms which 'extend outwardly from a central portion, or hub. The hub defines a cylindrical aperture which is adapted to receive a vertically oriented shaft which supports a chair seat and other chair components. In the case of a swivel chair, the lower end of the chair shaft may be arranged to rotate in the aperture. Castors or feet, are fitted to the distal end of the arms, remote from the hub.

The interface between the aperture and the lower end of the shaft 15 transmits the weight of the chair and the weight of a person sitting on a chair, to the hub and to the arms of the chair. Consequently, the hub has to be strong. In particular, in the case of a plastic chair base, the part of the chair base around the aperture has to be carefully designed and requires a large quantity of plastic material, in order to have sufficient strength to prevent the chair base from breaking under the weight of a person sitting on the chair.

Consequently, it is known to use a annular alumninium sleeve to define the aperture and to mould the chair base around that sleeve so that the alumninium sleeve provides additional strength in the area of the aperture.

However, this solution is expensive because aluminium is an expensive material to use and complicates the manufacturing process. Further, the use of aluminium has adverse consequences when recycling the chair base, since the aluminium has to be separated from the chair base for recycling.

The present invention seeks to alleviate the above me ntioned disadvantages.

Summary of the Invention According to a first aspect of the present invention there is provided a base for a chair comprising a central hub portion and a series of arms extending away from the central hub portion, the central hub portion defining an aperture which is lined with a sleeve and wherein the base comprises fibreglass reinforced nylon with a ratio of 25% to 35% fibreglass to nylon by weight, characterised in that the sleeve is made of glass reinforced nylon in which the ratio of fibreglass to nylon is 40% or more by weight.

The advantages of the present invention is that the nyion sleeve having a greater proportion of glass fill than would normally be used for the remainder of the base of the chair, provides substantially improved strength in the hub/aperture area and provides similar benefits to the use of an aluminium sleeve in terms of distributing loads and enabling the chair base to be manufactured with less material overall.

Further, the glass filled nylon sleeve bonds cheinically, as well as mechanically, to the rest of the chair base.

However in contrast with aluminium, being made of the same material as the chair base, it does not require separation from the chair base for recycling thus substantially improving the recycling qualities of the chair :base.

The invention also provides a sleeve for use in a chair base according ~:to the first aspect of the present invention wherein the sleeve is made from glass filled nylon.

In a preferred embodiment, the sleeve is 50% glass filled nylon.

The preferred manufacturing method involves first making the sleeve and then moulding the chair base around the sleeve.

One end of the sleeve may define a flange to assist in retaining the sleeve in the moulded chair base.

The invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 shows a top plan view of a chair base emibodying the present invention; Figure 2 shows a section through the chair base of Figure 1 along lines II IL: and Figure 3 shows a section through a sleeve.

Referring to the drawings, Figure 1 shows a plan view of a chair base, generally indicated at 10. The chair base has a central area, or hub, 12 from which radiate five equal-angular spaced arms 14. At the distal end of each arm, remote from the hub 12, a castor or foot, not shown, is provided.

The hub defines a gently tapering, but generally cylindrical, aperture 16 whose wall is defined by a sleeve 18. A rimi 20, best seen in Figure 2, extends around the upper end of the aperture.

The base is formed from an outer skin which defines the upper surface of the chair base, which can be seen in Figure 1, which is supported by a series of ribs which also give the chair base its necessary strength.

Referring to Figure 3, it can be seen that the sleeve 18 is generally annular although has a slight taper from an upper end to a lower end. The upper end of the sleeve defines an external flange 20. The inner surface of the lower end of the sleeve 22 is of reduced thickness. The chair base is made by moulding the base 10 around the sleeve. The flange 20 of the sleeve mechanically bonds the sleeve in the chair base. The reduced diameter lower end 22 of the sleeve assists in the manufacturing process in which the sleeve is located in a mould and the chair base moulded around the sleeve.

The sleeve is manufactured from fibre glass reinforced nylon, the fibre glass being present at least 50% by weight. The chair base itself is made from 30% glass reinforced nylon.

15 The use of the same materials to form the sleeve and the chair base, albeit in different proportions, makes the chair base easily recyclable, since it unnecessary to separate the sleeve and the base, prior to recycling.

The glass filed nylon sleeve also bonds better to the rest of the chair base than an aluminium sleeve.

20 It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the *I invention as broadly described. For example, although fibreglass and nylon are preferred, reinforcement/matrix materials the principal of the invention can apply to other reinforcement/matrix combinations. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

1. A base for a chair comprising a central hub portion and a series of arms extending away from the central hub portion, the central hub portion defining an aperture which is lined with a sleeve and wherein the base comprises fibreglass reinforced nylon with a ratio of 25% to 35% fibreglass to nylon by weight, characterised in that the sleeve is made of glass reinforced nylon in which the ratio of fibreglass to nylon is 40% or more by weight.

2. A chair base as claimed in claim 1 wherein the sleeve is at least fibre glass by weight.

3. A chair base as claimed in claim 1 of claim 2, wherein the base is less than 30% fibre glass by weight.

4. A chair base as claimed in any preceding claim wherein the sleeve defines an external flange at one end.

5. A sleeve for use in a chair base according to claim 1 wherein the 15 sleeve comprises a generally cylindrical tapering hollow cylinder defining an external flange at one end, the sleeve comprising fibre glass reinforced nylon, the ratio of fibre glass to nylon being at least 40% by weight.

6. A sleeve as claimed in claim 5 wherein the ratio of fibre glass to nylon in the sleeve comprises at least 50% by weight. 20

7. A chair base as claimed in any one of claims 1 to 4 and substantially as hereinbefore described with reference to the drawings. Dated this fifth day of November 1997 WASSON PLASTICS SALES PTY LTD AND ^UPt 0TDrsoPJ CF DYNAMIC FURfTURE eCOMPONENTS L-To')-rJ !SS.M'q G0oup PrY VD PTY LTD Patent Attorneys for the Applicant: F.B. RICE CO.